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@article{Afroughi2019,
author = {Mohammad Javad Afroughi and Farjad Falahati and Larry W. Kostiuk and Jason S. Olfert},
title = {Properties of carbon black produced by the thermal decomposition of methane in the products of premixed flames},
doi = {10.1016/j.jaerosci.2019.02.002},
pages = {13 -- 27},
volume = {131},
abstract = {The thermal decomposition of methane is a technique used to manufacture hydrogen gas and carbon black. The physical properties of carbon black produced by the thermal decomposition of methane (TDM) in the O2-deficient gas products of two premixed flames (propane- or methane-air) were investigated under different flow rates of decomposing methane injection (0.5-5 SLPM). An inverted burner was designed to provide a fuel-rich, laminar premixed flame, to produce hot gas into which methane was injected to thermally decompose inside a reactor. Particles from TDM were extracted by a nitrogen dilution system at the immediate exit of the reaction chamber, where another branch of the exhaust was dried and directed to a gas chromatograph. The carbon black particles were characterized by size resolved number concentration, mass concentration, effective density, volatility, and internal mixing state using different arrangements of a differential mobility analyzer, catalytic denuder, centrifugal particle mass analyzer, and condensation particle counter, as well as by morphology and primary particle size using transmission electron microscopy. A bimodal number-size distribution was observed at all conditions with count median diameters (CMDs) less than 58 nm and 21 nm when using propane- or methane-air premixed flames as the heat source, respectively. Higher number concentrations and mass concentrations with larger CMDs were achieved under lower flow rates of decomposing methane injection. For a given flow rate of decomposition methane, mass concentration and CMD increased significantly when using propane as the fuel, compared to the methane fuel. The size segregated mass fraction of internally mixed volatile content in particles was similar for both heat sources, showing a roughly constant fraction of volatile material in particles produced by the decomposition of 0.5 and 5 SLPM of methane (10% -- 30%) but a measurably larger fraction (55% - 30%) with a decreasing trend as a function of particle size from the decomposition of 1 SLPM of methane. The effective density of denuded particles was similar, but slightly higher, than the effective density of soot from a wide range of internal combustion engines. A higher denuded effective density was observed in the particles with higher volatile contents (particles from decomposition of 1 SLPM of methane), suggesting the restructuring of carbon black into more compact clusters due to excessive volatile condensation. TEM analysis revealed some similarity between the produced carbon black and engine soot in terms of morphology and primary particle diameter (both below 40  nm). Beside the carbon black properties, the efficiency of TDM in this configuration was also investigated by evaluation of methane destruction efficiency, as well as carbon black and hydrogen production efficiencies, based on the product gas composition and the particle mass concentration. It was found that longer residence times corresponding to lower flow rates resulted in higher conversion efficiencies in terms of methane destruction efficiency (maximum of 95%), hydrogen production efficiency (maximum of 80%), and carbon black production efficiency (maximum of 1%). It was concluded that the significantly low efficiency of carbon black production is due to the high amount of CO formation, likely through the gasification process.},
groups = {jolfert:6},
journal = {Journal of Aerosol Science},
keywords = {Carbon black, Thermal decomposition, Particle size, Particle morphology},
owner = {jolfert},
timestamp = {2019.03.11},
year = {2019}
}
@article{AHSAN2019133,
title = {Quantifying the carbon conversion efficiency and emission indices of a lab-scale natural gas flare with internal coflows of air or steam},
author = {Abbas Ahsan and Hamza Ahsan and Jason S. Olfert and Larry W. Kostiuk},
journal = {Experimental Thermal and Fluid Science},
year = {2019},
pages = {133 -- 142},
volume = {103},
abstract = {To better understand the effect of air- and steam-assist on flaring operations on carbon conversion efficiency and pollutant emissions, a lab-scale coflow burner constructed of two concentric circular tubes was used. Natural gas at 20 SLPM flowed through the annular space and increasing amounts of air or steam were added through the inner tube until flame extinction was invoked. The combustion products were captured by an exhaust hood and analyzed using a gas chromatograph to measure the concentrations of CH4, C2H6, C3H8, C4H10, CO and CO2. A photoacoustic extinctiometer and a NOx analyzer were used to measure black carbon and NOx concentrations, respectively. A challenge associated with the experiments was to accurately resolve stark transitions in conversion efficiency and orders of magnitude change in key emissions. Results indicated that the addition of air or steam to a natural gas jet diffusion flame caused a sudden collapse in carbon conversion efficiency, occurring at a coflow-fuel gas mass flow ratio of 1.8 for steam and 5.0 for air. As was expected, the CO2 emission indices for both air and steam coflow followed their respective carbon conversion efficiency trends. Conversely, the total unburned hydrocarbon emission indices increased with the reduction in carbon conversion efficiency. NOx emission indices for air and steam coflow were shown to decrease by an order of magnitude compared to the unassisted flame. For air coflow this occurred before the collapse in carbon conversion efficiency, while for steam coflow this occurred concurrently. Black carbon emission indices decreased rapidly by three orders of magnitude for both air and steam coflow. For both these lab-scale air and steam assisted flares there was a range of mass flow rates of the assist fluid that resulted in high combustion efficiency and low pollutant emissions.},
doi = {10.1016/j.expthermflusci.2019.01.013},
keywords = {Flaring, Natural gas, Steam, Coflow diffusion flame, Carbon conversion efficiency, Emission index}
}
@article{Azhdarzadeh2014b,
title = {Effect of Electrostatic Charge on Deposition of Uniformly Charged Monodisperse Particles in the Nasal Extrathoracic Airways of an Infant},
author = {Mehdi Azhdarzadeh and Jason S. Olfert and Reinhard Vehring and Warren H. Finlay},
journal = {Journal of Aerosol Medicine and Pulmonary Drug Delivery},
year = {2015},
number = {1},
pages = {30--34},
volume = {28},
abstract = {Background: The fraction of inhaled particles depositing in the nasal extrathoracic airways determines the amount of particles delivered to the lungs of infants. Electrostatic charge on particles can affect this deposition, and for this reason, deposition of charged aerosol particles in the Alberta Idealized Infant nasal geometry is examined.
Methods: Charged aerosol particles were generated via Plateau-Rayleigh jet breakup atomization with induction charging. Nasal deposition was measured by collecting particles on a filter membrane at the inlet and outlet of the airway and measuring their mass with an ultramicrobalance. The experiments were carried out using monodisperse, uniformly charged particles with aerodynamic diameters of 3–6 μm at two flow rates of 7.5 and 15 L/min, for a charge range of 0–10,000 e per particle.
Results: Electrostatic charge effects are largest for the lowest flow rate, smallest particle size, and highest charge level, with deposition in this case being approximately three times that for neutral particles. Higher flow rates and larger particle size result in much weaker electrostatic effects, with even the highest charge levels giving only a few percent higher deposition for the largest particle size and flow rate considered in this study. A dimensionless empirical relation based on the experimental data was developed for predicting deposition of charged particles in the idealized infant airway.
Conclusion: Electrostatic charge on inhaled aerosol particles has only a minor effect on deposition for large particles at higher flow rates, because in this case inertial impaction dominates deposition. However, for particles with low inertia, for example, small particles or low flow rates, large values of electrostatic charge strongly increase nasal deposition in the present infant extrathoracic airway.},
doi = {10.1089/jamp.2013.1118},
owner = {jolfert},
timestamp = {2014.03.18}
}
@article{Azhdarzadeh2014,
author = {Mehdi Azhdarzadeh and Jason S. Olfert and Reinhard Vehring and Warren H. Finlay},
title = {Effect of electrostatic charge on oral-extrathoracic deposition for uniformly charged monodisperse aerosols},
doi = {10.1016/j.jaerosci.2013.11.002},
pages = {38 - 45},
volume = {68},
journal = {Journal of Aerosol Science},
owner = {jolfert},
timestamp = {2013.11.29},
year = {2014}
}
@article{Azhdarzadeh2014c,
title = {Effect of Induced Charge on Deposition of Uniformly Charged Particles in a Pediatric Oral-Extrathoracic Airway},
author = {Azhdarzadeh, Mehdi and Olfert, Jason S. and Vehring, Reinhard and Finlay, Warren H.},
journal = {Aerosol Science and Technology},
year = {2014},
number = {5},
pages = {508-514},
volume = {48},
abstract = {An in vitro study was conducted in the Alberta idealized child mouth-throat, which mimics average deposition in a set of nine 6 to 14-year-old subjects, to examine the enhancement of deposition of monodisperse uniformly charged particles as a result of induced electrostatic forces. A purpose-based atomizer was designed and built for generating monodisperse, uniformly charged particles. The atomizer generates droplets by jet break up under the action of capillary waves and charges them via electrostatic induction. The experiments cover different particle aerodynamic diameters (da = 3.6, 4.4, and 5.9 um), at two flow rates (Q = 10 and 20 L/min), over a wide range of elementary charges per particle (0 - 10,000 e). The results show substantial increases in particle deposition in the present idealized pediatric mouth throat compared to neutral aerosols. Two empirical equations, as a function of Reynolds number, Stokes number, and induced charge number are introduced for the prediction of mouth-throat deposition in children, based on two different characteristic diameters of the airway. Copyright 2014 American Association for Aerosol Research},
doi = {10.1080/02786826.2014.896989},
owner = {jolfert},
timestamp = {2014.03.18}
}
@article{Azhdarzadeh2015,
title = {An atomizer to generate monodisperse droplets from high vapor pressure liquids},
author = {Mehdi Azhdarzadeh and Farzin M. Shemirani and Conor A. Ruzycki and Alberto Baldelli and James Ivey and David Barona and Tanya Church and David Lewis and Jason S. Olfert and Warren H. Finlay and Reinhard Vehring},
journal = {Atomization and Sprays},
year = {2016},
number = {2},
pages = {121--134},
volume = {26},
abstract = {This work describes an atomizer capable of generating monodisperse droplets of high vapor pressure liquids such as HFA227ea and HFA134a, which is expected to be a useful tool in future fundamental explorations of the mechanics of these highly dynamic aerosols. Hydrofluoroalkanes (HFAs) are the most common propellants in metered dose inhalers (MDIs), which are themselves the most common delivery method for pulmonary disease medications. As a result of the high vapor pressure of these fluids, generation of monodisperse droplets and their study are not possible with previously existing monodisperse atomizers due to fluid flashing when exposed to ambient conditions. The new atomizer uses a piezoelectric transducer to disintegrate the propellant jet, a cooling circuit with a low temperature limit of -30 C to reduce propellant vapor pressure, and a high pressure feed system (up to 2.7 MPa) to keep the propellant in the liquid phase, thereby avoiding flash atomization. In the current setup, the diameter of the generated droplets was monitored with a laser scattering system (using Fraunhofer diffraction theory) to optimize the operating parameters of the set-up (for example, the actuation frequency and amplitude of the piezoelectric transducer). This monitoring system allowed for the measurement of droplet geometric diameter, spacing, and velocity. The capabilities of the atomizer for generating monodisperse droplets are demonstrated by a case study in which monodisperse dry particles of beclomethasone dipropionate (BDP) are generated using a solution of BDP, ethanol co-solvent, and HFA134a propellant.},
doi = {10.1615/AtomizSpr.2015011631},
owner = {jolfert},
timestamp = {2015.05.08}
}
@article{Berg2009b,
title = {Overview of the {C}umulus {H}umilis {A}erosol {P}rocessing {S}tudy ({CHAPS})},
author = {Larry K. Berg and Carl M. Berkowitz and John A. Ogren and Chris A. Hostetler and Richard A. Ferrare and Manvendra Dubey and Elisabeth Andrews and Richard L. Coulter and Johnathan W. Hair and John M. Hubbe and Yin-Nan Lee and Claudio Mazzoleni and Jason Olfert and Stephen R. Springston},
journal = {Bulletin of the American Meteorological Society},
year = {2009},
pages = {1653--1667},
volume = {November},
abstract = {The primary goal of the Cumulus Humilis Aerosol Processing Study (CHAPS) was to characterize and contrast freshly emitted aerosols below, within, and above fields of cumuli, and to study changes to the cloud microphysical structure within these same cloud fields in the vicinity of Oklahoma City during June 2007. CHAPS is one of few studies that have had an aerosol mass spectrometer (AMS) sampling downstream of a counterflow virtual impactor (CVI) inlet on an aircraft, allowing the examination of the chemical composition of activated aerosols within the cumuli. The results from CHAPS provide insights into changes in the aerosol chemical and optical properties as aerosols move through shallow cumuli downwind of a moderately sized city. Three instrument platforms were employed during CHAPS, including the U.S. Department of Energy Gulfstream-1 aircraft, which was equipped for in situ sampling of aerosol optical and chemical properties; the NASA Langley King Air B200, which carried the downward-looking NASA Langley High Spectral Resolution Lidar (HSRL) to measure profiles of aerosol backscatter, extinction, and depolarization between the King Air and the surface; and a surface site equipped for continuous in situ measurements of aerosol optical properties, profiles of aerosol backscatter, and meteorological conditions, including total sky cover and thermodynamic profiles of the atmosphere. In spite of record precipitation over central Oklahoma, a total of 8 research flights were made by the G-1 and 18 by the B200, including special satellite verification flights timed to coincide with NASA satellite A-Train overpasses.},
doi = {10.1175/2009BAMS2760.1},
owner = {jolfert},
timestamp = {2009.06.11}
}
@article{Bezantakos2016a,
title = {Modification of the {TSI} 3081 Differential Mobility Analyzer to include three Monodisperse Outlets: {C}omparison between experimental and theoretical performance},
author = {S. Bezantakos and M. Giamarelou and L. Huang and J. Olfert and G. Biskos},
journal = {Aerosol Science and Technology},
year = {2016},
note = {One of 10 papers selected as a "notable paper" in 2016/17 by the Aerosol Science \& Technology Editors.},
number = {12},
pages = {1342--1351},
volume = {50},
abstract = {Differential mobility analyzers (DMAs) are widely used to determine the size of aerosol particles, and to probe their size-dependent physicochemical properties when two are employed in tandem. A limitation of tandem DMA (TDMA) systems is their long measuring cycle when the properties of more than one monodisperse population of particles need to be probed. In this work, we propose a simple modification of the classical cylindrical DMA by including three monodisperse-particle outlets in its central electrode (namely, the 3MO-DMA), with the objective of using it as the first DMA in TDMA systems for reducing their measuring cycle. The performance of the 3MO-DMA at different flow conditions was evaluated using laboratory-generated aerosol particles, and compared with theoretical predictions. The theory predicted accurately (i.e., within 3\%) the geometric mean diameters of the three distinct populations, as well as the resolutions of the first and the third outlet, under all experimental conditions. For the second outlet, the resolution was 10\% to 74\% lower than that predicted theoretically depending on the sheath-to-aerosol flow ratio. Nevertheless, the geometric standard deviation of the monodisperse aerosol from all the outlets was less than 1.09, which is sufficient for using the 3MO-DMA designed and tested in this work as a first DMA to produce a monodisperse aerosol flow containing three distinct particle populations in TDMA systems.},
doi = {10.1080/02786826.2016.1227060},
owner = {jolfert},
timestamp = {2016.08.15}
}
@article{Bhandari2017,
title = {Effect of Thermodenuding on the Structure of Nascent Flame Soot Aggregates},
author = {Bhandari, Janarjan and China, Swarup and Onasch, Timothy and Wolff, Lindsay and Lambe, Andrew and Davidovits, Paul and Cross, Eben and Ahern, Adam and Olfert, Jason and Dubey, Manvendra and Mazzoleni, Claudio},
journal = {Atmosphere},
year = {2017},
number = {9},
pages = {166},
volume = {8},
abstract = {The optical properties (absorption and scattering) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with materials that can condense on a freshly emitted (nascent) soot particle and coat it. This coating can affect the soot optical properties by refracting light, or by changing the soot aggregate structure. A common approach to studying the effect of coating on soot optical properties is to measure the absorption and scattering coefficients in ambient air, and then measure them again after removing the coating using a thermodenuder. In this approach, it is assumed that: (1) most of the coating material is removed; (2) charred organic coating does not add to the refractory carbon; (3) oxidation of soot is negligible; and, (4) the structure of the pre-existing soot core is left unaltered, despite the potential oxidation of the core at elevated temperatures. In this study, we investigated the validity of the last assumption, by studying the effect of thermodenuding on the morphology of nascent soot. To this end, we analyzed the morphological properties of laboratory generated nascent soot, before and after thermodenuding. Our investigation shows that there is only minor restructuring of nascent soot by thermodenuding.},
doi = {10.3390/atmos8090166},
owner = {jolfert},
timestamp = {2017.09.06}
}
@article{Boies2015,
title = {Particle Emission Characteristics of a Gas Turbine with a Double Annular Combustor},
author = {Adam M. Boies and Marc E. J. Stettler and Jacob J. Swanson and Tyler J. Johnson and Jason S. Olfert and Mark Johnson and Max L. Eggersdorfer and Theo Rindlisbacher and Jing Wang and Kevin Thomson and Greg Smallwood and Yura Sevcenco and David Walters and Paul I. William and Joel Corbin and Amewu A. Mensah and Jonathan Symonds and Ramin Dastanpour and Steven N. Rogak},
journal = {Aerosol Science \& Technology},
year = {2015},
pages = {842--855},
volume = {49},
doi = {10.1080/02786826.2015.1078452},
owner = {jolfert},
timestamp = {2015.08.06}
}
@article{Broda2018,
title = {A novel inversion method to determine the mass distribution of non-refractory coatings on refractory black carbon using a centrifugal particle mass analyzer and single particle soot photometer},
author = {K. N. Broda and J. S. Olfert and M. Irwin and G. P. Schill and G. R. McMeeking and E. G. Schnitzler and W. J\"{a}ger},
journal = {Aerosol Science and Technology},
year = {2018},
note = {Selected as a "notable paper" in 2018 by the Aerosol Science \& Technology Editors.},
number = {5},
pages = {567-578},
volume = {52},
abstract = {ABSTRACT A novel inversion method is presented, which derives the two-variable number distribution for black carbon aerosol, using a coupled centrifugal particle mass analyzer (CPMA) and single particle soot photometer (SP2). The CPMA classifies all particles by their mass-to-charge ratio, and the SP2 detects the mass of refractive black carbon (rBC) in each individual particle. The results of the inversion are the simultaneous number distributions of both rBC mass and total particle mass. Using the distribution, the coating distribution on a population of rBC particles can be identified visually. Furthermore, the distribution can be integrated to find one-variable mass and number concentration distributions as a function of total or rBC particle mass. These capabilities were demonstrated via smog chamber experiments, where an organic (non-rBC) coating was grown onto uncoated rBC aerosol over several hours via photo-oxidation of p-xylene. The particle distributions were constructed using the inversion over a range of 1-60 fg of total particle mass. As the non-rBC coating thickness increased over time, a shift in the number distribution toward higher total mass was observed. At the end of the experiment, uncoated rBC was injected into the chamber, and the distribution was clearly resolved using the inversion. The CPMA-SP2 method offers several advantages over ''SP-2 only'' methods, namely, (i) coating mass information can be obtained over a wider range of total particle mass, (ii) total particle mass is measured directly, and (iii) it does not make core-shell morphology assumptions. Copyright © 2018 American Association for Aerosol Research},
doi = {10.1080/02786826.2018.1433812},
owner = {jolfert},
publisher = {Taylor \& Francis},
timestamp = {2018.04.16}
}
@article{Bullock2014,
title = {Size, volatility, and effective density of particulate emissions from a homogeneous charge compression ignition engine using compressed natural gas},
author = {Dallin S. Bullock and Jason S. Olfert},
journal = {Journal of Aerosol Science},
year = {2014},
pages = {1--8},
volume = {75},
comment = {The particle size distribution, volatility, and effective density of particulate matter emitted from a homogeneous charge compression ignition (HCCI) engine fueled by port injected compressed natural gas were measured and compared to emissions emitted from the same engine during motoring and spark ignition for two compression ratios. The particle concentration and geometric mean diameter were greater at high compression ratio, and also, the total particulate mass was lower for spark ignition and homogeneous charge compression ignition than during motoring. Volatility tests showed that all operating conditions have less than 5% of the particulate matter remaining when denuding the sample at 100 °C. Effective density measurements also show that the particles for each operating mode have a relatively constant density with respect to particle size (approximately 850 kg/m3).},
doi = {10.1016/j.jaerosci.2014.04.005},
owner = {jolfert},
timestamp = {2014.04.25}
}
@article{Cappa2012,
title = {Radiative absorption enhancements due to the mixing state of atmospheric black carbon},
author = {Cappa, C.D. and Onasch, T.B. and Massoli, P. and Worsnop, D.R. and Bates, T.S. and Cross, E.S. and Davidovits, P. and Hakala, J. and Hayden, K.L. and Jobson, B.T. and Kolesar, K.R. and Lack, D.A. and Lerner, B.M. and Li, S.-M. and Mellon, D. and Nuaaman, I. and Olfert, J.S. and Pet\"{a}j\"{a}, T. and Quinn, P.K. and Song, C. and Subramanian, R. and Williams, E.J. and Zaveri, R.A.},
journal = {Science},
year = {2012},
number = {6098},
pages = {1078-1081},
volume = {337},
abstract = {Atmospheric black carbon (BC) warms Earth?s climate, and its reduction has been targeted for near-term climate change mitigation. Models that include forcing by BC assume internal mixing with non-BC aerosol components that enhance BC absorption, often by a factor of ~2; such model estimates have yet to be clearly validated through atmospheric observations. Here, direct in situ measurements of BC absorption enhancements (Eabs) and mixing state are reported for two California regions. The observed Eabs is small-6% on average at 532 nm-and increases weakly with photochemical aging. The Eabs is less than predicted from observationally constrained theoretical calculations, suggesting that many climate models may overestimate warming by BC. These ambient observations stand in contrast to laboratory measurements that show substantial Eabs for BC are possible.},
document_type = {Article},
doi = {10.1126/science.1223447},
owner = {jolfert},
source = {Scopus},
timestamp = {2012.09.25}
}
@article{Cappa2013,
title = {Response to Comment on ``{R}adiative Absorption Enhancements Due to the Mixing State of Atmospheric Black Carbon''},
author = {Cappa, Christopher D. and Onasch, Timothy B. and Massoli, Paola and Worsnop, Douglas R. and Bates, Timothy S. and Cross, Eben S. and Davidovits, Paul and Hakala, Jani and Hayden, Katherine L. and Jobson, B. Tom and Kolesar, Katheryn R. and Lack, Daniel A. and Lerner, Brian M. and Li, Shao-Meng and Mellon, Daniel and Nuaaman, Ibraheem and Olfert, Jason S. and Pet\"{a}j\"{a}, Tuukka and Quinn, Patricia K. and Song, Chen and Subramanian, R. and Williams, Eric J. and Zaveri, Rahul A.},
journal = {Science},
year = {2013},
number = {6118},
pages = {393},
volume = {339},
abstract = {Jacobson argues that our statement that ``many climate models may overestimate warming by BC'' has not been demonstrated. Jacobson challenges our results on the basis that we have misinterpreted some model results, omitted optical focusing under high relative humidity conditions and by involatile components, and because our measurements consist of only two locations over short atmospheric time periods. We address each of these arguments, acknowledging important issues and clarifying some misconceptions, and stand by our observations. We acknowledge that Jacobson identified one detail in our experimental technique that places an additional constraint on the interpretation of our observations and reduces somewhat the potential consequences of the stated implications.},
doi = {10.1126/science.1230260},
owner = {jolfert}
}
@article{CrossES2010,
title = {Soot particle studies-instrument inter-comparison-project overview},
author = {Cross,E. S. and Onasch,T. B. and Ahern,A. and Wrobel,W. and Slowik,J. G. and Olfert,J. and Lack,D. A. and Massoli,P. and Cappa,C. D. and Schwarz,J. P. and Spackman,J. R. and Fahey,D. W. and Sedlacek,A. and Trimborn,A. and Jayne,J. T. and Freedman,A. and Williams,L. R. and Ng,N. L. and Mazzoleni,C. and Dubey,M. and Brem,B. and Kok,G. and Subramanian,R. and Freitag,S. and Clarke,A. and Thornhill,D. and Marr,L. C. and Kolb,C. E. and Worsnop,D. R. and Davidovits,P.},
journal = {Aerosol Science and Technology},
year = {2010},
number = {8},
pages = {592-611},
volume = {44},
abstract = {An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer?Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratio (1.8 - PHI - 5), particle shape (mass-mobility exponent ( D_fm ), 2.0 - D_fm - 3.0), particle mobility size (30 - d_m - 300 nm), black carbon mass (0.07 - m_BC - 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 - delta r_ve - 201 nm) where r ve is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.},
doi = {10.1080/02786826.2010.482113}
}
@article{Dastanpour2017a,
title = {Variation of the optical properties of soot as a function of particle mass},
author = {Ramin Dastanpour and Ali Momenimovahed and Kevin Thomson and Jason Olfert and Steven Rogak},
journal = {Carbon},
year = {2017},
pages = {201 - 211},
volume = {124},
doi = {http://dx.doi.org/10.1016/j.carbon.2017.07.005},
issn = {0008-6223},
owner = {jolfert},
timestamp = {2017.09.01}
}
@article{Dastanpour2016,
title = {Improved sizing of soot primary particles using mass-mobility measurements},
author = {Ramin Dastanpour and Steven N. Rogak and Brian Graves and Jason Olfert and Maximilian L. Eggersdorfer and Adam M. Boies},
journal = {Aerosol Science and Technology},
year = {2016},
note = {One of 10 papers selected as a ``notable paper'' in 2016/17 by the Aerosol Science \& Technology Editors.},
number = {2},
pages = {101--109},
volume = {50},
abstract = {ABSTRACTThe properties and impacts of aggregated aerosol particles (i.e., soot, metal oxide fumes) depend on their morphology, as characterized by fractal dimension, prefactor, and primary particle diameter. The morphology may be measured directly by time-consuming ex situ microscopy or rapid but indirect in situ methods. Previously, it was found that particle mass and mobility measurements could be used for the estimation of the primary particle diameter of zirconia aggregates, using plausible assumptions related to the fractal structure (specifically, prefactor and exponent ). Since the formation and growth of zirconia aggregates are different from carbon soot, here we compare primary particle diameters measured directly from transmission electron microscopy analysis of soot particles with the diameters estimated from mass-mobility measurements. Performing extensive measurements on soot emissions from two reciprocating engines over a range of operating conditions, we found that there are no universal values of and that can be used for all conditions. However, new optimized values of and are estimated here for soot particles. The variation of the primary particle diameter with particle size is also taken into consideration and is shown to be essential to obtain physically realistic results. Using optimized values of and , the average primary particle sizing error is reduced for all soot types. This suggests that with some calibration, in situ sizing of the primary particle diameter, using mass and mobility measurements, can provide useful accuracy.© 2016 American Association for Aerosol Research},
doi = {10.1080/02786826.2015.1130796},
owner = {jolfert},
timestamp = {2016.01.25}
}
@article{Dickau2015,
title = {Demonstration of the {CPMA}-Electrometer System for Calibrating Black Carbon Particulate Mass Instruments},
author = {Matthew Dickau and Tyler J Johnson and Kevin Thomson and Greg Smallwood and Jason S Olfert},
journal = {Aerosol Science and Technology},
year = {2015},
number = {3},
pages = {152--158},
volume = {49},
abstract = {In an effort to improve regulations for particulate emissions from aircraft engines, the Aircraft Exhaust Emissions Measurement Committee, SAE E-31, is investigating instruments to measure black carbon mass concentration in real time. The current candidates are a laser-induced incandescence instrument (LII 300) and a photo-acoustic Micro-Soot Sensor (MSS). However, both of these instruments use indirect techniques, measuring parameters other than the actual mass of particulate in the exhaust, and therefore require calibration. Previously, it has been shown that a centrifugal particle mass analyzer (CPMA) can be used in conjunction with an aerosol electrometer to traceably generate an aerosol with known mass concentration. This system can be used to rapidly calibrate particle mass instruments (on the order of minutes), without the time-consuming process of filter sampling which is often used for calibration and prone to sampling artifacts. Here we demonstrate the feasibility of the CPMA-electrometer system for calibrating two LII 300 instruments and two MSS instruments, which were calibrated to the NIOSH 5040 standard. The correlations between the CPMA-electrometer system and the challenge instrument were highly linear for both the LII and the MSS, and agreed well with the previous calibration. All four instruments were found to correlate with the CPMA-electrometer system with R^2 values of 0.993 to 0.999. The standard uncertainty in the CPMA-electrometer system averaged 4.3% and was as low as 2.6% for some measurements. With a simple improvement to the aerosol electrometer, we estimate this average uncertainty would be less than 3%. This lower uncertainty and much higher speed of measurement support the use of the CPMA-electrometer system as a mass measurement calibration method for black carbon instruments.},
doi = {10.1080/02786826.2015.1010033},
owner = {jolfert},
timestamp = {2015.02.12}
}
@article{Dickau2016,
title = {Methodology for Quantifying the Volatile Mixing State of an Aerosol},
author = {Matthew Dickau and Jason Olfert and Marc Stettler and Adam Boies and Ali Momenimovahed and Kevin Thomson and Greg Smallwood and Mark Johnson},
journal = {Aerosol Science and Technology},
year = {2016},
note = {One of 10 papers selected as a "notable paper" in 2016/17 by the Aerosol Science \& Technology Editors.},
number = {8},
pages = {759--772},
volume = {50},
abstract = {Mixing state refers to the relative proportions of chemical species in an aerosol, and the way these species are combined; either as a population where each particle consists of a single species (‘externally mixed’) or where all particles individually consist of two or more species (‘internally mixed’) or the case where some particles are pure and some particles consist of multiple species. The mixing state affects optical and hygroscopic properties, and quantifying it is therefore important for studying an aerosol's climate impact. In this article, we describe a method to quantify the volatile mixing state of an aerosol using a differential mobility analyzer, centrifugal particle mass analyzer, catalytic denuder, and condensation particle counter by measuring the mass distributions of the volatile and non-volatile components of an aerosol and determining how the material is mixed within and between particles as a function of mobility diameter. The method is demonstrated using two aerosol samples from a miniCAST soot generator, one with a high elemental carbon (EC) content, and one with a high organic carbon (OC) content. The measurements are presented in terms of the mass distribution of the volatile and non-volatile material, as well as measures of diversity and mixing state parameter. It was found that the high-EC soot nearly consisted of only pure particles where 86% of the total mass was non-volatile. The high-OC soot consisted of either pure volatile particles or particles that contained a mixture of volatile and non-volatile material where 8% of the total mass was pure volatile particles and 70% was non-volatile material (with the remaining 22% being volatile material condensed on non-volatile particles).},
doi = {10.1080/02786826.2016.1185509},
owner = {jolfert},
timestamp = {2016.04.15}
}
@article{Ferraz2016,
title = {Enhanced Evaporation of Micro-Scale Droplets with an Infrared Laser},
author = {Luis A. Ferraz-Albani and Alberto Baldelli and Chrissy J. Knapp and Wolfgang J{\"a}ger and Reinhard Vehring and David S. Nobes and Jason S. Olfert and Larry W. Kostiuk},
journal = {Journal of Heat Transfer},
year = {2017},
pages = {011503--011503-8},
volume = {139},
doi = {10.1115/1.4034486},
owner = {jolfert},
timestamp = {2016.08.10}
}
@article{Forestieri2018,
title = {Measurement and modeling of the multiwavelength optical properties of uncoated flame-generated soot},
author = {Forestieri, S. D. and Helgestad, T. M. and Lambe, A. T. and Renbaum-Wolff, L. and Lack, D. A. and Massoli, P. and Cross, E. S. and Dubey, M. K. and Mazzoleni, C. and Olfert, J. S. and Sedlacek III, A. J. and Freedman, A. and Davidovits, P. and Onasch, T. B. and Cappa, C. D.},
journal = {Atmospheric Chemistry and Physics},
year = {2018},
number = {16},
pages = {12141--12159},
volume = {18},
doi = {10.5194/acp-18-12141-2018}
}
@article{Ghazi2013,
title = {Coating Mass Dependence of Soot Aggregate Restructuring due to Coatings of Oleic Acid and Dioctyl Sebacate},
author = {Ghazi, R. and Olfert, J. S.},
journal = {Aerosol Science and Technology},
year = {2013},
number = {2},
pages = {192-200},
volume = {47},
abstract = {Soot particles in the atmosphere can be coated with organic or nonorganic material, which may affect particle morphology and optical properties. The effect of the mass of coating on the morphology of soot particles was studied using oleic acid and dioctyl sebacate (DOS) coatings. A wide range of coatings were used, with up to 10Â times as much coating as the mass of the soot. It is shown that as the coating mass increases the degree of collapsing increases until the coating is so large that the soot particle becomes completely contained within a spherical droplet of the coating material. Higher amounts of coating will not cause further collapse of the particle. The degree of collapse is also a function of the initial size of the soot particle but was independent of the coating materials tested, which have similar surface tensions. A model is presented to predict the change in mobility diameter as a function of coating mass ratio. The effect of coating mass on effective density, shape factor, and fractal dimension is also reported.},
doi = {10.1080/02786826.2012.741273},
owner = {jolfert},
timestamp = {2012.11.15}
}
@article{Ghazi2013a,
title = {Mass, Mobility, Volatility, and Morphology of Soot Particles Generated by a {M}c{K}enna and Inverted Burner},
author = {Ghazi, Rouzbeh and Tjong, Hugo and Soewono, Arka and Rogak, Steven N. and Olfert, Jason S.},
journal = {Aerosol Science and Technology},
year = {2013},
number = {4},
pages = {395-405},
volume = {47},
abstract = {Particle mass, mobility, volatile mass fraction, effective density, mass concentration, mass–mobility exponent, and particle morphology were measured from soot generated from a premixed flame (McKenna burner) and an inverted diffusion flame over a range of equivalence ratios. It was found that the mass fraction of volatile material on the soot from the McKenna burner could be up to 0.83 at a high equivalence ratio, but there was no measurable volatile material on the soot from the inverted burner. The inverted burner can produce soot at different mass–mobility exponents, ranging from 2.23 to 2.54, over a range of global equivalence ratios of 0.53–0.67, while the mass–mobility exponent ranges from 2.19 to 2.99 for fresh soot and 2.19 to 2.81 for denuded soot for the McKenna burner at equivalence ratios of 2.0–3.75. Transmission electron microscopy analysis of inverted burner soot shows that a range of particle morphologies is present at a given global equivalence ratio, likely due to different local equivalence ratios and flame conditions in the diffusion flame. Primary particle diameter tends to increase with aggregate size, which could contribute to the mass–mobility exponent being well above 2. Copyright 2013 American Association for Aerosol Research},
doi = {10.1080/02786826.2012.755259},
owner = {jolfert},
timestamp = {2013.01.08}
}
@article{GolshashiL2010,
title = {Deposition of inhaled ultrafine aerosols in replicas of nasal airways of infants},
author = {Golshahi,L. and Finlay,W. H. and Olfert,J. S. and Thompson,R. B. and Noga,M. L.},
journal = {Aerosol Science and Technology},
year = {2010},
number = {9},
pages = {741-752},
volume = {44},
abstract = {Experimentally measured deposition of ultrafine particles, ranging from 13?100 nm in diameter, in nasal airway replicas of ten infants aged 3?18 months is presented. The replicas included the face, nostrils, and nasal airways including the upper trachea. A differential mobility analyzer (DMA) and a condensation particle counter (CPC) were used to quantify the nasal deposition by comparing the number of polydisperse sodium chloride particles, generated by evaporation from a Collison atomizer, at the inlet and outlet of the replicas. Particles were individually classified in size by DMA and subsequently were counted one size bin at a time by CPC upstream and downstream of each replica. Since in vivo data is not available for infants to compare to, we validated our experimental procedure instead by comparing deposition in nasal airway replicas of six adults with in vivo measurements reported in literature. In the infant replicas, tidal inhalation was simulated at two physiologically compatible flow rates and the effect of flow rate on deposition was found to be small. Deposition obtained at constant flow rates is lower than with tidal breathing, indicating the importance of unsteadiness, in contrast to similar data in adults where unsteadiness is known to be unimportant. An empirical equation, containing geometrical features of the nasal airways in the form of related non-dimensional dynamical parameters (Reynolds, Schmidt, and Womersley numbers), was best fitted to the infant data. This equation may be useful for a priori prediction of nasal deposition and intersubject variability during exposure of infants to ultrafine aerosols.},
doi = {10.1080/02786826.2010.488256}
}
@article{GomezJ2011,
title = {Influence of two-phase feed bubble size on effervescent atomization in a horizontal nozzle assembly},
author = {Gomez,J. and Fleck,B. and Olfert,J. and McMillan,J.},
journal = {Atomization and Sprays},
year = {2011},
number = {3},
pages = {249-261},
volume = {21},
abstract = {An experimental study is presented of a spray atomizer used in heavy oil upgrading. Bubble size in the feed flow was observed to determine its influence on the atomization of an effervescent nozzle. Experiments were conducted with water and air in a two-phase flow, commercial-scale facility at ambient conditions (horizontal air/water bubbly feed in a 25.4 mm tube to a single contraction throat diameter of 12.7 mm). Different mixtures were tested with water flow rates from 113 to 200 kg/min and 1 to 4 kg/min for air flow rate, achieving an air liquid ratio, ?, from 1% to 4%. The range of feed parameters would result in flow regimes that were either bubbly or intermittent in equilibrium horizontal flow. Two bubble breakers (perforated plates) were used to modify the size of the bubbles in the conduit feeding the nozzle. Bubbles and droplets were measured with visualization techniques using front lighting for bubbles and shadowgraphy for droplets. A single location in the spray cone was chosen as the characteristic location in the flow where droplet size and distribution are most representative of the mass flow of the spray liquid. Acquired images were used to estimate the size and shape and calculate Sauter mean diameter. The experiments indicate that the influence of the scale of bubbles in the feed on the reduction of droplet size resulted in the atomization and support the need for attention in designing the feed delivery premixing and transport to the nozzle.},
doi = {10.1615/AtomizSpr.2011003241}
}
@article{Graves2015,
title = {Characterization of Particulate Matter Morphology and Volatility from a Compression-Ignition Natural Gas Direct-Injection Engine},
author = {Brian Graves and Jason Olfert and Bronson Patychuk and Ramin Dastanpour and Steven Rogak},
journal = {Aerosol Science and Technology},
year = {2015},
pages = {589--598},
volume = {49},
abstract = {The particulate matter (PM) emitted from a single-cylinder compression-ignition, natural-gas engine fitted with a High-Pressure Direct-Injection (HPDI) system distinctly different from a duel fuel engine was investigated, and characterized by size distribution, morphology, mass-mobility exponent, effective density, volatility, mixing state, and primary particle size using transmission electron microscopy (TEM), and tandem measurements from differential mobility analyzers (DMA) and a centrifugal particle mass analyzer (CPMA). Six engine conditions were selected with varying load, speed, exhaust gas recirculation (EGR) fraction, and fuel delivery strategy. An increase in engine load increased both the number concentration and the geometric mean diameter of the particulate. The fraction of the number of purely volatile particles to total number of particles (number volatile fraction, NVF) was found to decrease as load increased, although at the lower speed, partially premixed mode, the lowest NVF. All size distributions were also found to be unimodal. The size-segregated ratio of the mass of internally mixed volatile material to total particle mass (mass volatile fraction, MVF) decreased with load and with particle mobility-equivalent diameter. A roughly constant amount of volatile material is likely produced at each engine mode, and the decrease in MVF is due to the increase in PM number with load. Effective density and mass-mobility exponent of the non-volatile soot at the different engine loads were the same or slightly higher than soot from traditional diesel engines. Denuded effective density trends were observed to collapse to approximately the same line, although engine modes with higher MVFs had slightly higher effective densities suggesting that the soot structures have collapsed into more dense shapes—a suspicion that is confirmed with TEM images. TEM results also indicated that primary particle size first decreases from low to medium load, then increases from medium to high load. An increase in EGR was also seen to increase primary particle size. Coefficients were determined for a relation that gives primary particle diameter as a function of projected area equivalent diameter. A decrease in load or speed results in a stronger correlation.},
doi = {10.1080/02786826.2015.1050482},
owner = {jolfert},
timestamp = {2015.05.08}
}
@article{Graves2017,
title = {Morphology and Volatility of Particulate Matter Emitted from a Gasoline Direct Injection Engine Fuelled on Gasoline and Ethanol Blends},
author = {Brian Mackenzie Graves and Charles Robert Koch and Jason Scott Olfert},
journal = {Journal of Aerosol Science},
year = {2017},
pages = {166--178},
volume = {105},
abstract = {Abstract The particulate matter emitted from a turbocharged, four cylinder, wall-guided, gasoline direct injection (GDI) engine fuelled with gasoline and ethanol blends was investigated, and characterized by size distribution, mass-mobility exponent, effective density, and volatility using tandem measurements from differential mobility analysers (DMA) and a centrifugal particle mass analyser (CPMA). Three engine loads were tested at 2250 \{RPM\} (4%, 13%, and 26% of maximum load) in addition to an idle condition while the engine was fuelled using gasoline mixed with ethanol fractions of 0% (E0), 10% (E10), and 50% (E50) by volume. An increase in engine load increased particle number concentration, although idle produced approximately as many particles as at 13% load. In the majority of cases, an increase in ethanol fraction decreased number concentration. The fraction of the number of particles comprised of only volatile material to total number of particles (number volatile fraction) both overall and as a function of particle mobility-equivalent diameter was under 10 percent at all engine conditions and fuels (measured after a three-way catalytic converter). The size-segregated ratio of the mass of internally mixed volatile material to total particle mass was similarly low. Volatility measurements were conducted using a thermodenuder set to 300 C. Mass-mobility exponent was seen to range between 2.28 and 2.60. Effective density increased with load, and in general mass-mobility exponent increased as well. Effective density decreased with an increase in ethanol fraction and a slight decrease in mass-mobility exponent was also observed for all conditions except idle. No significant changes in effective density, particle size, or number concentration were observed in \{GDI\} soot after denuding particle samples.},
doi = {10.1016/j.jaerosci.2016.10.013},
owner = {jolfert},
timestamp = {2016.10.31}
}
@article{Gysel2011,
title = {Effective density of Aquadag and fullerene soot black carbon reference materials used for {SP}2 calibration},
author = {Gysel, M. and Laborde, M. and Olfert, J.S. and Subramanian, R. and Gr\"{o}hn, A.J.},
journal = {Atmospheric Measurement Techniques},
year = {2011},
number = {12},
pages = {2851-2858},
volume = {4},
abstract = {The mass and effective density of black carbon (BC) particles generated from aqueous suspensions of Aquadag and fullerene soot was measured and parametrized as a function of their mobility diameter. The measurements were made by two independent research groups by operating a differential mobility analyser (DMA) in series with an aerosol particle mass analyser (APM) or a Couette centrifugal particle mass analyser (CPMA). Consistent and reproducible results were found in this study for different production lots of Aquadag, indicating that the effective density of these particles is a stable quantity and largely unaffected by differences in aerosol generation procedures and suspension treatments. The effective density of fullerene soot particles from one production lot was also found to be stable and independent of suspension treatments. Some differences to previous literature data were observed for both Aquadag and fullerene soot at larger particle diameters. Knowledge of the exact relationship between mobility diameter and particle mass is of great importance, as DMAs are commonly used to size-select particles from BC reference materials for calibration of single particle soot photometers (SP2), which quantitatively detect the BC mass in single particles.},
doi = {10.5194/amt-4-2851-2011},
owner = {jolfert},
timestamp = {2012.09.25}
}
@article{JOHNSON2021105705,
title = {Generating an aerosol of homogeneous, non-spherical particles and measuring their bipolar charge distribution},
journal = {Journal of Aerosol Science},
volume = {153},
pages = {105705},
year = {2021},
doi = {10.1016/j.jaerosci.2020.105705},
author = {Tyler J. Johnson and Robert T. Nishida and Xiao Zhang and Jonathan P.R. Symonds and Jason S. Olfert and Adam M. Boies},
keywords = {Charge distribution, Bipolar charging, Non-spherical particles, Aerosol classifiers, Homogeneous particle source},
abstract = {The Aerodynamic Aerosol Classifier (AAC) and Differential Mobility Analyzer (DMA) are aerosol classifiers commonly used to generate a monodispersed aerosol by selecting particles within a narrow range of relaxation times or electrical mobilities, respectively. However, generating an aerosol of homogeneous particles, which has narrow ranges of particle mass, mobility and relaxation time simultaneously, with either of these methods is challenging. Particles classified by the DMA are often not homogeneous (or monodispersed) due to multiply-charged particles. While the AAC overcomes this challenge for spherical particles, homogeneity is not achieved with non-spherical particles due to their effective density varying with particle size. This study demonstrates using an AAC and DMA in tandem to generate an aerosol of homogeneous, non-spherical particles. This approach is validated using scanning electron microscope (SEM) images and electrical mobility measurements of the tandem-classified particles to highlight their homogeneity. To limit the effects of multiple charging during DMA classification, only a subset of DMA and AAC setpoints are permitted. While this subset is not representative of ?average? non-spherical particles from the same aerosol source, this subset of low-density particles deviates the most from spherical morphology, and thus, provides insights into the upper bound of other particle properties, such as charging. Using this approach to select homogeneous particles, the bipolar charge distribution of low-density soot aggregates is then measured using another DMA. This AAC-DMA-DMA approach is demonstrated to measure up to 17 individual charge states (i.e. ?8 to +8) after neutralization (with 85Kr) of size-resolved, soot aggregates with mobility diameters between 80 and 433?nm. The low-density soot aggregates obtain higher charges than predicted by theory, which overestimates the uncharged fraction (by 0.042?0.069) and, to a lesser extent, the single charge fractions (by up to 0.037) of the low-density soot aggregates, while underestimating their proportion of multiple charging (by up to 0.135 cumulatively at one particle size or up to 0.039?at one multiple charge state and size). These charging discrepancies represent an upper bound of the bipolar charging of average aggregates from the same source of flame soot.}
}
@article{Johnson2018c,
author = {Tyler J. Johnson and Martin Irwin and Jonathan P. R. Symonds and Jason S. Olfert and Adam M. Boies},
title = {Measuring aerosol size distributions with the aerodynamic aerosol classifier},
doi = {10.1080/02786826.2018.1440063},
number = {6},
pages = {655-665},
volume = {52},
abstract = {The Aerodynamic Aerosol Classifier (AAC) is a novel instrument that selects aerosol particles based on their relaxation time or aerodynamic diameter. Additional theory and characterization is required to allow the AAC to accurately measure an aerosol’s aerodynamic size distribution by stepping while connected to a particle counter (such as a Condensation Particle Counter, CPC). To achieve this goal, this study characterized the AAC transfer function (from 32 nm to 3 μm) using tandem AACs and comparing the experimental results to the theoretical tandem deconvolution. These results show that the AAC transmission efficiency is 2.6-5.1 times higher than a combined Krypton-85 radioactive neutralizer and Differential Mobility Analyzer (DMA), as the AAC classifies particles independent of their charge state. However, the AAC transfer function is 1.3-1.9 times broader than predicted by theory. Using this characterized transfer function, the theory to measure an aerosol aerodynamic size distribution using an AAC and particle counter was developed. The transfer function characterization and stepping deconvolution were validated by comparing the size distribution measured with an AAC-CPC system against parallel measurements taken with a Scanning Mobility Particle Sizer (SMPS), CPC, and Electrical Low Pressure Impactor (ELPI). The effects of changing AAC classifier conditions on the particle selected were also investigated and found to be small (<1.5\%) within its operating range.},
groups = {[jolfert:]},
journal = {Aerosol Science and Technology},
year = {2018}
}
@article{Johnson2014b,
title = {Steady-state measurement of the effective particle density of cigarette smoke},
author = {Tyler J. Johnson and Jason S. Olfert and Ross Cabot and Conor Treacy and Caner U. Yurteri and Colin Dickens and John McAughey and Jonathan P.R. Symonds},
journal = {Journal of Aerosol Science},
year = {2014},
pages = {9--16},
volume = {75},
doi = {10.1016/j.jaerosci.2014.04.006},
owner = {jolfert},
timestamp = {2014.04.25}
}
@article{Johnson2015a,
title = {Transient measurement of the effective particle density of cigarette smoke},
author = {Tyler J. Johnson and Jason S. Olfert and Ross Cabot and Conor Treacy and Caner U. Yurteri and Colin Dickens and John McAughey and Jonathan P. R. Symonds},
journal = {Journal of Aerosol Science},
year = {2015},
pages = {63--74},
volume = {87},
doi = {10.1016/j.jaerosci.2015.05.006},
owner = {jolfert},
timestamp = {2015.05.13}
}
@article{Johnson2014,
title = {Effective density and mass-mobility exponent of aircraft turbine particulate matter},
author = {Tyler J. Johnson and Jason S. Olfert and Jonathan P.R. Symonds and Mark Johnson and Theo Rindlisbacher and Jacob J. Swanson and Adam M. Boies and Kevin Thomson and Greg Smallwood and
David Walters and Yura Sevcenco and Andrew Crayford and Ramin Dastanpour and Steven N. Rogak and Lukas Durdina and Yeon Kyoung Bahk and Benjamin Brem and Jing Wang},
journal = {Journal of Propulsion and Power},
year = {2015},
number = {2},
pages = {573--582},
volume = {31},
doi = {10.2514/1.B35367},
owner = {jolfert},
timestamp = {2014.04.16}
}
@article{Johnson2015,
title = {Hygroscopic effects on the mobility and mass of cigarette smoke particles},
author = {Tyler J. Johnson and Jason S. Olfert and Caner U. Yurteri and Ross Cabot and John McAughey},
journal = {Journal of Aerosol Science},
year = {2015},
pages = {69--78},
volume = {86},
abstract = {The hygroscopic growth of particles, produced from a University of Kentucky 3R4F reference cigarette smoked following Health Canada Intense (HCI) puffing parameters (55 mL puff of 2 s duration, every 30 s), was measured in terms of the electrical mobility diameter and particle mass, using a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) and Centrifugal Particle Mass Analyzer (CPMA) system. Both the particle mobility diameter and mass growth factors were found to agree with previously determined values and hygroscopicity models. The mobility diameter growth factor of the particles produced from either a University of Kentucky 3R4F or 1R5F reference cigarette, following HCI puffing parameters, were found to be very similar. As the relative humidity (RH) approached saturation, the effects of the initial particle size on the mobility growth factor became more dominant, with larger particles growing proportionally larger than smaller particles. From the measured mobility diameter and mass growth factors, the density growth factor was calculated. This parameter showed that the particle density increased as the sample relative humidity increased. This case is only possible, given that the dried smoke particle density (1109 ± 118 kg/m3) was determined to be greater than the density of water, if the water condensation on the smoke particle dissolves at least a portion of it, resulting in a significant increase in mass with only a small increase volume.},
doi = {10.1016/j.jaerosci.2015.04.005},
owner = {jolfert},
timestamp = {2015.05.08}
}
@article{Johnson2013c,
title = {Mass-Mobility Measurements Using a Centrifugal Particle Mass Analyzer and Differential Mobility Spectrometer},
author = {Johnson, Tyler J. and Symonds, Jonathan P. R. and Olfert, Jason S.},
journal = {Aerosol Science and Technology},
year = {2013},
number = {11},
pages = {1215-1225},
volume = {47},
abstract = {Mass-mobility measurements using a centrifugal particle mass analyzer (CPMA) and differential mobility spectrometer (DMS) are demonstrated. The CPMA, which classifies an aerosol by mass-to-charge ratio, is used upstream of a DMS, which measures the mobility size distribution of the mass-classified particles in real-time. This system allows for mass?Äìmobility measurements to be made on transient sources at one particle mass or an entire effective density distribution for steady state sources in minutes. Since the CPMA classifies particles by mass-to-charge ratio and multiply charged particles are present, particles of several different masses will be measured by the DMS. Therefore, a correction scheme is required to make accurate measurements. To validate this measurement scheme, two different CPMA-DMS systems were used to measure the known density of di(2ethylhexyl) sebacate (DEHS). The first system consisted of a CPMA and standard DMS500 (Cambustion). This system measured an average effective density of 1027 kg/m3 or within 12.6% of the accepted value with an estimated uncertainty of 30.1% (with 95% confidence). The second system consisted of a CPMA and modified DMS. The modified DMS was a DMS500 with the corona charger disabled and sample and sheath flow rates lowered, decreasing the uncertainty in the mobility measurement. This system measured an average effective density of 964 kg/m3 or within 5.7% of the accepted value with an uncertainty of 9.5-10.4% depending on particle mobility size. Finally, it was determined that multiple-charge correction and size calibration were required, with each correction causing a maximum change in measured effective density greater than 10%.},
doi = {10.1080/02786826.2013.830692},
owner = {jolfert},
timestamp = {2013.09.18}
}
@article{Kazemimanesh2016b,
title = {Probe sampling to map and characterize nanoparticles along the axis of a laminar methane jet diffusion flame},
author = {Mohsen Kazemimanesh and Alireza Moallemi and Jason S. Olfert and Larry W. Kostiuk},
journal = {Proceedings of the Combustion Institute},
year = {2017},
number = {1},
pages = {881--888},
volume = {36},
abstract = {Nanoparticles generated by a laminar methane jet diffusion flame were characterized by direct sampling through the pinhole of a probe and sized with a nano-scanning mobility particle sizer. Particular attention was paid to verify the validity of the probe-sampling technique. Results showed that the particle size distributions (PSD) were strongly affected by sample dilution immediately after extraction. Within the flame, the soot PSD did not become independent of dilution ratio until the sample was diluted several thousand times (depending on initial concentration) within a few milliseconds of extraction. A method for on-line measurement of dilution ratio was also introduced by measuring CO2 concentration continuously during the tests.
High spatially resolved experimental results at different heights (typically 1 mm apart) along the central axis of the flame showed the evolution of PSD for particles larger than 2 nm covering early nucleation and growth to oxidation regions. Moving upward from the fuel-side, prior to the visible flame, the PSD in the particle nucleation region was bimodal (with one of the modes being smaller than 2 nm) and gradually turned into a unimodal PSD with a median of 10 nm due to particle growth. Nearer to the visible flame, the PSD became bimodal again with the larger-diameter mode growing in magnitude and being made up of ever-larger particles, while the smaller-diameter mode gradually shrunk in size until it vanished. Eventually, as the flow was leaving the visible flame, all the particles gradually oxidized until at the tip of the flame they reached a median diameter of 9 nm and in very low concentrations.},
doi = {10.1016/j.proci.2016.06.169},
owner = {jolfert}
}
@article{Lee2010,
title = {Determination of particle temperatures in a silica-generating counterflow flame via flame emission measurements},
author = {Jeonghoon Lee and Jason Olfert and Igor S. Altman and Mansoo Choi},
journal = {International Journal of Heat and Mass Transfer},
year = {2010},
pages = {564--567},
volume = {53},
abstract = {We propose a simple technique to measure particle temperatures in a particle generating counterflow flame. The silica particle temperature was derived from flame light emission measurements. This technique allows the non-intrusive measurement of particle temperatures over 2000 K. In addition, the OH concentration distribution in the hydrogen?oxygen flame was estimated from flame emission spectra in the ultraviolet region. A numerical model of the combustion processes, which included the reactions of SiCl4 leading to the formation of silica particles, verified that the measured particle temperatures and OH concentration were close to the theoretical values.},
doi = {10.1016/j.ijheatmasstransfer.2009.09.036},
owner = {jolfert},
timestamp = {2009.06.11}
}
@article{Leung2017a,
title = {Relationship between Coating-Induced Soot Aggregate Restructuring and Primary Particle Number},
author = {Leung, Kaiser K. and Schnitzler, Elijah G. and Dastanpour, Ramin and Rogak, Steven N. and J\"{a}ger, Wolfgang and Olfert, Jason S.},
journal = {Environmental Science \& Technology},
year = {2017},
number = {15},
pages = {8376-8383},
volume = {51},
abstract = {The restructuring of monodisperse soot aggregates due to coatings of secondary organic aerosol (SOA) was investigated in a series of photo-oxidation chamber experiments. Soot aggregates were generated by one of three sources (an ethylene premixed burner, a methane inverted diffusion burner, or a diesel generator), treated by denuding, size-selected by a differential mobility analyzer, and injected into a smog chamber, where they were exposed to the photo-oxidation products of p-xylene, which partitioned to form SOA coatings. The evolution of aggregates from their initial to final morphologies was investigated in situ by mobility and mass measurements and ex situ by transmission electron microscopy. At a given initial aggregate mobility diameter, diesel aggregates are less dense and composed of smaller primary particles than those generated by the two burners, and they restructure to a smaller final mobility diameter. Remarkably, the final degrees of restructuring of aggregates from all three sources exhibit the same linear dependence on the number of primary particles per aggregate. The observed linear relationship, valid for the atmospherically relevant SOA coating investigated here, could allow modelers to predict the evolution of aggregate morphology based on a single property of the aggregates.},
doi = {10.1021/acs.est.7b01140},
owner = {jolfert},
timestamp = {2017.08.16}
}
@article{Leung2017b,
title = {Relative Humidity Dependence of Soot Aggregate Restructuring Induced by Secondary Organic Aerosol: Effects of Water on Coating Viscosity and Surface Tension},
author = {Kaiser K. Leung and Elijah G. Schnitzler and Wolfgang J\"{a}ger and Jason S. Olfert},
journal = {Environmental Science \& Technology Letters},
year = {2017},
number = {9},
pages = {386-390},
volume = {4},
abstract = {Soot aggregates have a significant warming effect on climate, and their structural and optical properties may evolve in the presence of coatings. Here, the relative humidity (RH) dependence of soot aggregate restructuring induced by secondary organic aerosol (SOA) coatings was investigated in a series of photo-oxidation experiments. Burner-generated soot aggregates were classified by mobility diameter and injected into a smog chamber, where they were exposed to oxidation products of p-xylene; coated aggregates were subsequently conditioned at one of the following RHs: <12\%, 20\%, 40\%, 60\%, or 85\%. Changes in diameter and mass were monitored using differential mobility and centrifugal particle mass analyzers, respectively. At RH < 12\%, the SOA coating was too viscous to induce restructuring, so the particle diameter increased uniformly with coating mass. At RH ‚â• 20\%, the SOA coating induced restructuring, and the degree of restructuring increased with RH, indicating that the decreased viscosity and increased surface tension of SOA have significant implications on SOA-induced restructuring of soot aggregates. At RH ‚ 60\%, appreciable water uptake occurred, and the hygroscopicity parameter of the SOA coating was derived. Our results provide crucial insights into the complex interactions between soot, SOA, and water in the atmosphere.},
doi = {10.1021/acs.estlett.7b00298},
owner = {jolfert},
timestamp = {2017.09.22}
}
@article{Moallemi2018,
title = {The Effect of Sodium Chloride on the Nanoparticles Observed in a Laminar Methane Diffusion Flame},
author = {Alireza Moallemi and Mohsen Kazemimanesh and Larry W. Kostiuk and Jason S. Olfert},
journal = {Combustion and Flame},
year = {2018},
pages = {273--283},
volume = {188},
doi = {10.1016/j.combustflame.2017.10.009},
owner = {jolfert},
timestamp = {2017.10.27}
}
@article{Momenimovahed2015,
author = {A. Momenimovahed and D. Handford and M.D. Checkel and J.S. Olfert},
title = {Particle number emission factors and volatile fraction of particles emitted from on-road gasoline direct injection passenger vehicles},
doi = {10.1016/j.atmosenv.2014.11.045},
pages = {105 -- 111},
volume = {102},
abstract = {Abstract Particle number emission factors, and the volatility of the particles, are measured on-road for five gasoline direct injection vehicles over a wide range of operating conditions including urban and highway driving conditions. Two condensation particle counters (CPC) were used to measure nascent and non-volatile (thermodenuded) particle concentrations for transient urban and highway tests. To measure the non-volatile concentration and also the volatility of the particles, a thermodenuder was employed to remove the semi-volatile material from the aerosol sample. Rapid accelerations were also studied in more detail by measuring the particle size distributions in real-time using a differential mobility spectrometer (DMS). The ratio of semi-volatile particles to total particle number is generally higher during acceleration followed by the idle operating mode. The number emission factors (for particles larger than 2.5 nm) ranged between 5.46 × 1011–3.50 × 1012/km for freshly emitted (nascent) particles and between 2.87 × 1011–3.31 × 1012/km for non-volatile (thermodenuded) particles. More particles per kilometer are produced during acceleration compared to cruise conditions where the non-volatile particle number emission factor for acceleration is 2.3 and 1.8 times higher than vehicle cruise for urban and highway driving cycles, respectively. Particle number emission factor models are also presented in terms of particle emission rate as a function of vehicle tractive power and also as a function of vehicle specific power as defined for the \{US\} Environmental Protection Agency's \{MOVES\} model.},
journal = {Atmospheric Environment},
keywords = {Gasoline direct injection},
owner = {jolfert},
timestamp = {2014.12.02},
year = {2015}
}
@article{Momenimovahed2014,
title = {Real-time driving cycle measurements of ultrafine particle emissions from two wheelers and comparison with passenger cars},
author = {Ali Momenimovahed and Jason Olfert and David Checkel and Sunil Pathak and Vineet Sood and Yograj Singh and S.K. Singal},
journal = {International Journal of Automotive Technology},
year = {2014},
number = {7},
pages = {1053--1061},
volume = {15},
abstract = {Two wheel vehicles (scooters and motorcycles) make up 74% of the vehicle population in India. An experimental study has been conducted to assess and compare the particulate emissions from several two wheelers and passenger car in a typical Indian fleet. The vehicles, including four 4-stroke, two 2-stroke two-wheelers, and one gasoline-LPG bi-fuel passenger cars, were tested on a chassis dynamometer using the Indian Driving Cycle. A differential mobility spectrometer was employed to measure the particle size distribution in real-time in the range of 5 nm to 560 nm. Particulate size distributions from the two-wheelers were typically bi-modal. The count median diameter with 4-stroke two wheelers was observed in the range of 26 nm to 48 nm. The number and mass emission factors ranged between 9.5 × 1012 km−1 to 1.3 × 1013 km−1 and 0.80 mg/km to 40 mg/km; respectively. In the case of 2-stroke two wheelers, it was observed that not only the count median diameter is 3 times larger compared to 4-strokes, but also 2-stroke vehicles produce 5 times more particles in term of number and about 60 times more particles in terms of mass. The 2-stroke and 4-stroke two wheelers produced particulate emissions (both in terms of number and mass), which were higher than a gasoline and a LPG passenger vehicle operating on the same driving cycle.},
doi = {10.1007/s12239-014-0109-4},
owner = {jolfert},
timestamp = {2014.04.25}
}
@article{Momenimovahed2013,
title = {Effect of fuel choice on nanoparticle emission factors in {LPG}-gasoline bi-fuel vehicles},
author = {Momenimovahed, A. and Olfert, J.S. and Checkel, M.D. and Pathak, S. and Sood, V. and Robindro, L. and Singal, S.K. and Jain, A.K. and Garg, M.O.},
journal = {International Journal of Automotive Technology},
year = {2013},
pages = {1--11},
volume = {14},
abstract = {Nanoparticle and gas-phase emission factors are presented for a liquefied petroleum gas (LPG) passenger vehicle and are compared to gasoline operation. A bi-fuel LPG-gasoline vehicle certified for use on either fuel was used as the test vehicle so that a direct comparison of the emissions could be made based on fuel choice. These values were considered along with previous studies to determine the relative change in particulate emissions due to fuel choice over a wide range of vehicles and operating conditions. The vehicle examined in this study was tested on a chassis dynamometer for both steadystate and transient conditions. Transient test cycles included the US FTP72 driving cycle, Japanese driving cycle and modified Indian driving cycle while steady-state tests were done at vehicle speeds ranging from 10-90 km/hr in various transmission gears. Exhaust particle size distributions were measured in real-time using a differential mobility spectrometer (DMS50), and particle number and particle mass emission factors were calculated. For both fuels, the majority of the particles ranged from 5 to 160 nm in terms of particle diameter, with typically more than 85% of the particles in the nucleation mode (between 5?50 nm). In most cases, the vehicle produced a greater fraction of larger (accumulation mode) particles when fuelled on LPG. Using the data in the literature as well as the data in the current study, gasoline fuel produces 4.6 times more particles in terms of number and 2.1 times more particles in terms of mass.},
doi = {10.1007/s12239-013-0001-7},
issue = {1},
keywords = {Nanoparticles; Emission factor; Liquefied petroleum gas; Bi-fuel vehicle},
language = {English},
owner = {jolfert},
publisher = {The Korean Society of Automotive Engineers},
timestamp = {2013.02.01}
}
@article{Momenimovahed2015b,
title = {Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement},
author = {A. Momenimovahed and J. S. Olfert},
journal = {Aerosol Science and Technology},
year = {2015},
number = {11},
pages = {1051--1062},
volume = {49},
abstract = {The effective density and volatility of particulate emissions from five gasoline direct injection (GDI) passenger vehicles were measured using a tandem differential mobility analyzer (DMA) and centrifugal particle mass analyzer (CPMA) system. The measurements were conducted on a chassis dynamometer at three steady-state operating conditions. A thermodenuder was employed to find the volatility and mixing state of the particles as well as the effective density of nascent and non-volatile particles (defined as particle phase remaining after denuding at 200°C). The mass–mobility exponent ranged between 2.4 and 2.7 for nascent (or undenuded) particles and between 2.5 and 2.7 for non-volatile particles; higher than typical diesel soot. The effective density function was 4278dm−0.438 ± 76.3 kg/m3 (for mobility diameter, dm, in nm) for nascent particles and 3215dm−0.395 ± 37.9 kg/m3 for non-volatile particles. The effective density functions of the non-volatile particles were fairly similar for the conditions studied. The uncertainty in using the effective density and mixing state data to determine the mass concentration of the aerosol by integrating mobility size distributions was examined. The uncertainty in mass concentration is minimized when only the non-volatile component is measured. However, the uncertainty in the mass concentration increases substantially if nascent particles are measured due to uncertainties in the particle mixing state and their associated effective densities. Furthermore, transient vehicle operation (cold-starts, accelerations, and decelerations) would likely change the mixing state of the exhaust particles suggesting it is difficult to accurately measure the mass concentration of undenuded GDI exhaust particulate using integrated size distribution methods.},
doi = {10.1080/02786826.2015.1094181},
owner = {jolfert},
timestamp = {2015.10.29}
}
@article{Morin2014,
title = {Performance of Pressurized Metered-Dose Inhalers at Extreme Temperature Conditions},
author = {Morin, Chelsea M. D. and Ivey, James W. and Titosky, Jordan T. F. and Suderman, Jonathan D. and Olfert, Jason S. and Vehring, Reinhard and Finlay, Warren H.},
journal = {Journal of Pharmaceutical Sciences},
year = {2014},
number = {11},
pages = {3553--3559},
volume = {103},
abstract = {The performance of pressurized metered-dose inhalers (pMDIs) under a variety of temperature conditions was investigated. The effects of both inhaler temperature and ambient temperature were considered. The inhaler temperature ranged from ‚13.0C to 41.7C and the ambient temperature ranged from ‚12.0C to 41.7C. The in vitro lung dose was measured for four widely available pMDIs: AiromirTM, QVARTM, Symbicort, and Ventolin. The in vitro lung dose through an Alberta Idealized Throat was measured by gravimetric assay, which was verified by UV spectroscopic assay. A decrease in the in vitro lung dose was observed for all evaluated pMDIs when ambient temperature and device temperature were simultaneously reduced, decreasing on average by 70% at the coldest temperatures, whereas increasing on average by 25% at the elevated temperature condition. In vitro lung dose is strongly dependent on both inhaler temperature and ambient temperature with the tested pMDIs.},
doi = {10.1002/jps.24145},
keywords = {temperature, pressurized metered-dose inhaler (pMDI), aerosols, microparticles, in vitro models, pulmonary drug delivery, Airomir, stability, QVARTM, Symbicort, Ventolin},
owner = {jolfert},
timestamp = {2014.10.31}
}
@article{OlfertJ02,
title = {A Numerical Calculation of the Transfer Function of the Fluted Centrifugal Particle Mass Analyzer},
author = {Jason Olfert},
journal = {Aerosol Science and Technology},
year = {2005},
pages = {1002--1009},
volume = {39},
abstract = {A new particle mass classifier called the Fluted Centrifugal Particle Mass Analyzer (CPMA) is presented and compared to the Aerosol Particle Mass (APM) Analyzer and the Couette CPMA. These particle mass classifiers use electrostatic and centrifugal forces to classify particles by their mass-to-charge ratio. The Fluted CPMA uses reversed ?scooped? sections to create a stable system of forces in the radial direction but not in the angular direction. The stable forces in the radial direction improve the transfer function of the classifier. A Lagrangian model (neglecting diffusion) of the Fluted CPMA is derived from which the transfer function of the classifier is found. The model shows that, like the APM and Couette CPMA, a single non-dimensional number determines the shape of the transfer function. The comparison of the classifiers shows that the Couette CPMA outperforms the Fluted CPMA and APM. However, the Fluted CPMA outperforms the APM over a wide range of operating conditions and may be easier to manufacture than the Couette CPMA.},
doi = {10.1080/02786820500380222}
}
@article{OlfertJ01,
title = {New method for particle mass classification --- {T}he {C}ouette centrifugal particle mass analyzer},
author = {Jason Olfert and Nick Collings},
journal = {Journal of Aerosol Science},
year = {2005},
pages = {1338--1352},
volume = {36},
abstract = {A new particle mass classifier, the Couette centrifugal particle mass analyzer (CPMA), is described and compared to the existing aerosol particle mass (APM) analyzer. The Couette CPMA and APM use centrifugal and electrostatic forces to classify particles according to their mass-to-charge ratio. The APM consists of two rotating coaxial electrodes, rotating at the same angular velocity, between which charged particles pass. Depending on the voltage and rotational speeds of the electrodes, particles of different mass-to-charge ratios will be classified. The Couette CPMA uses a similar operating procedure, but the inner electrode rotates slightly faster than the outer. This produces a stable system of forces that dramatically improves the transfer function of the classifier. Two theoretical models of the classifiers are developed. One model neglects the effects of diffusion and the other model does not. The models show that the shape of the transfer function for both devices is determined by two non-dimensional constants. The models also show that the Couette CPMA has better performance characteristics than the APM when transfer functions are compared.},
doi = {10.1016/j.jaerosci.2005.03.006}
}
@article{OlfertJ05,
title = {An ultrasonic sound speed sensor for measuring exhaust gas recirculation levels},
author = {J. S. Olfert and M. D. Checkel},
journal = {Journal of Automobile Engineering},
year = {2007},
pages = {181--189},
volume = {221},
abstract = {Exhaust gas recirculation (EGR) has been used for years to improve the performance of internal combustion engines. This paper shows that acoustic methods can be used to measure EGR. Theory is presented which shows that measurements of the speed of sound can be used to measure the amount of EGR in the intake manifold. In particular, a new method called the discrete acoustic wave and phase detection (DAWPD) method can be used to measure EGR levels with a fast-response time. Experimental results show that a DAWPD sensor can be used to measure EGR levels with adequate accuracy (+/- 1.3 per cent EGR) at steady state. Transient measurements were not possible owing to engine limitations. The sensor's performance was limited by the ultrasonic transducers used. It is postulated that sensor performance could be improved with smaller and temperature-independent non-resonant transducers.},
doi = {10.1243/09544070JAUTO194}
}
@article{OlfertJ03,
title = {A fuel quality sensor for fuel cell vehicles, natural gas vehicles, and variable gaseous fuel vehicles},
author = {J. S. Olfert and M. D. Checkel},
journal = {Society of Automotive Engineers},
year = {2005},
note = {SAE Paper 2005-01-3770},
abstract = {There are many possible applications for the discrete acoustic wave and phase detection (DAWPD) sound speed sensor. The DAWPD sensor is a compact sensor that measures the sound speed of gases. The sound speed of gaseous fuels can be related to various properties of a fuel including composition. A sound speed sensor can be used as a fuel quality sensor in natural gas vehicles (NGVs), variable gaseous fuel (VGF) vehicles (a VGF vehicle uses a mixture of hydrogen and natural gas fuel), and proton exchange membrane (PEM) fuel cell vehicles (FCVs). In a NGV the DAWPD sensor can be used to measure the methane number, Wobbe number, and hydrogen-to-carbon ratio of the natural gas. The DAWPD sensor can also be used to find the composition of the fuel used in VGF vehicles. In PEM fuel cell vehicles small amounts of CO (>25 ppm) can poison the fuel cell. The DAWPD sensor can measure the amount of CO in the hydrogen fuel in order to control the fuel reforming process. For all three applications the DAWPD sensor can be used in conjunction with a feed-forward control system to optimize the performance of the vehicles. This paper presents the theory relating the sound speed of gaseous fuels to the property of interest for each powertrain. Experimental results are presented for measurements of nitrogen/methane mixtures (representative of natural gas) and methane/hydrogen mixtures as used in NGV and VGF vehicles, respectively. The experimental results show that the DAWPD sensor has adequate accuracy for use in NGV and VGF vehicles. Theoretical results show that the DAWPD sensor also has adequate accuracy for PEM FCVs.},
doi = {10.4271/2005-01-3770}
}
@article{OlfertJ06,
title = {Acoustic method for measuring the sound speed of gases over small path lengths},
author = {J. S. Olfert and M. D. Checkel and C. R. Koch},
journal = {Review of Scientific Instruments},
year = {2007},
pages = {054901},
volume = {78},
abstract = {Acoustic ?phase shift? methods have been used in the past to accurately measure the sound speed of gases. In this work, a phase shift method for measuring the sound speed of gases over small path lengths is presented. We have called this method the discrete acoustic wave and phase detection (DAWPD) method. Experimental results show that the DAWPD method gives accurate (+/-3.2?m/s) and predictable measurements that closely match theory. The sources of uncertainty in the DAWPD method are examined and it is found that ultrasonic reflections and changes in the frequency ratio of the transducers (the ratio of driving frequency to resonant frequency) can be major sources of error. Experimentally, it is shown how these sources of uncertainty can be minimized.},
doi = {10.1063/1.2736406}
}
@article{Olfert2017,
title = {Effective Density and Volatility of Particles Sampled from a Helicopter Gas Turbine Engine},
author = {Jason S. Olfert and Matthew Dickau and Ali Momenimovahed and Meghdad Saffaripour and Kevin Thompson and Greg Smallwood and Marc E. J. Stettler and Adam Boies and Yura Sevcenco and Andrew Crayford and Mark Johnson},
journal = {Aerosol Science and Technology},
year = {2017},
number = {6},
pages = {704--714},
volume = {51},
abstract = {AbstractThe effective density and size-resolved volatility of particles emitted from a Rolls-Royce Gnome helicopter turboshaft engine are measured at two engine speed settings (13,000 and 22,000 RPM). The effective density of denuded and undenuded particles were measured. The denuded effective densities are similar to the effective densities of particles from a gas turbine with a double annular combustor as well as a wide variety of internal combustion engines. The denuded effective density measurements were also used to estimate the size and number of primary particles in the soot aggregates. The primary particle size estimates show that the primary particle size was smaller at lower engine speed (in agreement with transmission electron microscopy analysis). As a demonstration, the size-resolved volatility of particles emitted from the engine are measured with a system consisting of a differential mobility analyzer, centrifugal particle mass analyzer, condensation particle counter, and catalytic stripper. This system determines the number distributions of particles that contain or do not contain non-volatile material, and the mass distributions of non-volatile material, volatile material condensed onto the surface of non-volatile particles, and volatile material forming independent particles (e.g. nucleated volatile material). It was found that the particulate at 13,000 RPM contained a measurable fraction of purely volatile material with diameters below 25 nm and had a higher mass fraction of volatile material condensed on the surface of the soot (12%) compared to the 22,000 RPM condition (5%). This study demonstrates the potential to quantify the distribution of volatile particulate matter and gives additional information to characterize sampling effects with regulatory measurement procedures.},
doi = {10.1080/02786826.2017.1292346},
owner = {jolfert},
timestamp = {2017.02.09}
}
@article{Olfert2008,
title = {Measuring aerosol size distributions with the fast integrated mobility spectrometer},
author = {Olfert, J. S. and Kulkarni, P. and Wang, J.},
journal = {Journal of Aerosol Science},
year = {2008},
month = nov,
number = {11},
pages = {940--956},
volume = {39},
abstract = {A fast integrated mobility spectrometer (FIMS) has been developed for rapid aerosol size distribution measurements including those aerosols with low particle number concentrations. In this work, an inversion routine has been developed for the FINIS and it is demonstrated that the FIMS can accurately measure aerosol size distributions. The inversion routine includes corrections for the particle residence time in the FINIS and other factors related to the width of the response (or transfer) function and multiple charging of particles. Steady-state size distributions measured with the FIMS compared well with those measured by a scanning mobility particle sizer (SNIPS). Experiments also show that the FIMS is able to capture the size distribution of rapidly changing aerosol populations. The total particle concentration integrated from distributions measured by the FIMS agrees well with simultaneous measurements by a condensation particle counter (CPC).},
af = {Olfert, Jason S.EOLEOLKulkarni, PramodEOLEOLWang, Jian},
c1 = {[Olfert, Jason S.; Wang, Jian] Brookhaven Natl Lab, Div Atmospher Sci, Upton, NY 11973 USA.EOLEOL[Kulkarni, Pramod] NIOSH, Ctr Dis Control & Prevent, Cincinnati, OH 45226 USA.},
de = {Aerosol size distribution; Fast response; Electrical mobility; FastEOLEOLintegrated mobility spectrometer},
di = {10.1016/j.jaerosci.2008.06.005},
doi = {10.1016/j.jaerosci.2008.06.005},
em = {jian@bnl.gov},
fu = {Office of Biological and Environmental Research, Department of EnergyEOLEOL(DOE) [DE-AC02-98CH10866]; Office of Global Programs of NationalEOLEOLOceanic and Atmospheric Administration [NRMT0000-5-203]; LaboratoryEOLEOLDirected Research and Development program at the Brookhaven NationalEOLEOLLaboratory (BNL) ; Brookhaven Science Associates},
fx = {This work was supported by the Office of Biological and EnvironmentalEOLEOLResearch, Department of Energy (DOE), under Contract DE-AC02-98CH10866,EOLEOLthe Office of Global Programs of National Oceanic and AtmosphericEOLEOLAdministration under Contract NRMT0000-5-203, and the LaboratoryEOLEOLDirected Research and Development program at the Brookhaven NationalEOLEOLLaboratory (BNL). BNL is operated for the DOE by Battelle MemorialEOLEOLInstitute. Jason Olfert also acknowledges partial support from theEOLEOLGoldhaber Distinguished Fellowship from Brookhaven Science Associates.EOLEOLThe authors also wish to acknowledge Dr. Peter Takacs for his help withEOLEOLthe optics on the FIMS.},
ga = {381LT},
j9 = {J AEROSOL SCI},
ji = {J. Aerosol. Sci.},
keywords = {REAL-TIME MEASUREMENT; TWOMEY ALGORITHM; LINEAR INVERSION; ANALYZER; IMPACTOR; COUNTER},
la = {English},
nr = {19},
owner = {jolfert},
pa = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND},
pg = {17},
pi = {OXFORD},
publisher = {Pergamon-Elsevier Science Ltd},
rp = {Wang, J, Brookhaven Natl Lab, Div Atmospher Sci, Bldg 815E, Upton, NYEOLEOL11973 USA.},
sc = {Engineering, Chemical; Engineering, Mechanical; Environmental Sciences;EOLEOLMeteorology & Atmospheric Sciences},
sn = {0021-8502},
tc = {1},
timestamp = {2009.05.13},
ut = {ISI:000261538300003}
}
@article{OlfertJ04,
title = {The experimental transfer function of the {C}ouette centrifugal particle mass analyzer},
author = {J. S. Olfert and K. St.J. Reavell and M. Rushton and Nick Collings},
journal = {Journal of Aerosol Science},
year = {2006},
pages = {1840--1852},
volume = {37},
abstract = {The Couette centrifugal particle mass analyzer (CPMA) classifies particles by their mass-to-charge ratio. Unlike the aerosol particle mass (APM) analyzer, the Couette CPMA uses a stable system of forces to improve the transfer function of the classifier. A prototype Couette CPMA has been built and tested. The experimental results from the prototype agree well with theory and it is found that indeed the transfer function of the Couette CPMA is better than the APM's. Experimental work is shown using a differential mobility analyzer (DMA) and Couette CPMA to classify polystyrene latex (PSL) and di-2-ethylhexyl sebacate (DEHS) particles. By measuring the mass of PSL particles the absolute uncertainty of the Couette CPMA was found to be 6.7?38% higher in terms of mass (or 2.2?11% higher in terms of equivalent diameter) than the expected value. However, when the DMA?CPMA system was calibrated with PSL particles the density of DEHS particles was measured to within approximately 3% of the expected value.},
doi = {10.1016/j.jaerosci.2006.07.007}
}
@article{OlfertJ07,
title = {The effective density and fractal dimension of particles emitted from a light-duty diesel vehicle with a diesel oxidation catalyst},
author = {J. S. Olfert and J. P. R. Symonds and Nick Collings},
journal = {Journal of Aerosol Science},
year = {2007},
pages = {69--82},
volume = {38},
abstract = {A differential mobility analyzer (DMA) and a Couette centrifugal particle mass analyzer (Couette CPMA) were used to measure the effective density and fractal dimension of particles emitted from a light-duty diesel vehicle fitted with a diesel oxidation catalyst (DOC). It was found that at high engine loads, the DOC increased in temperature, sulphate levels in the particulate matter increased, and a transient nucleation mode was observed. The increase in sulphate levels resulted in a drastic increase in the effective density and fractal dimension of the particles. At low engine loads (8?15%), sulphate levels were much lower, no nucleation mode was present and the fractal dimension varied from 2.22 to 2.48, which is in good agreement with previous studies. At 40% load, sulphate levels were much higher and the fractal dimension was 2.76.},
doi = {10.1016/j.jaerosci.2006.10.002}
}
@article{Olfert2009,
title = {Dynamic Characteristics of a Fast-Response Aerosol Size Spectrometer},
author = {Olfert, J. S. and Wang, J.},
journal = {Aerosol Science and Technology},
year = {2009},
number = {2},
pages = {97--111},
volume = {43},
abstract = {The fast integrated mobility spectrometer (FIMS) is a highly sensitive instrument with a fast response time. The time response of the FIMS is limited by the mixing of the aerosol in the inlet of the instrument, which "smears" the detected aerosol over a range of time. The response time is also limited by the different transit times that particles experience in the instrument due to differences in particle classification trajectories. Experiments show that the difference in particle transit times can be corrected using a simple model of the particle trajectories. Furthermore, the "smearing" effects in the inlet can be corrected by de-convolving the time series of particle counts (the temporal de-convolution) in each size bin before inverting the data. The dynamic response of the FIMS was investigated by measuring an aerosol subjected to a step-change and sinusoidal-change in number concentration. The attenuation of the FIMS signal, without using the temporal de-convolution, was measured with and without an aerosol neutralizer in the FIMS inlet. Due to its large internal volume, the neutralizer significantly slows down the time response of the FIMS when installed in the inlet. For a sinusoidal signal at 0.33 Hz, the measured attenuation of the FIMS without the neutralizer was 56% versus an attenuation of 82% when the neutralizer was used. When the temporal de-convolution was applied at the same frequency, the FIMS was able to capture the full variation of the aerosol size distribution; however the random noise in the derived size distribution was amplified.},
af = {Olfert, Jason S.EOLEOLWang, Jian},
c1 = {[Olfert, Jason S.; Wang, Jian] Brookhaven Natl Lab, Dept Atmospher Sci, Upton, NY 11973 USA.},
di = {10.1080/02786820802495488},
doi = {10.1080/02786820802495488},
em = {jian@bnl.gov},
fu = {Office of Biological and Environmental Research, Department of EnergyEOLEOL(DOE) [DE-AC02-98CH10866]; Laboratory Directed Research and DevelopmentEOLEOL; Brookhaven National Laboratory (BNL) ; Brookhaven Science Associates},
fx = {This work was supported by the Office of Biological and EnvironmentalEOLEOLResearch, Department of Energy (DOE), under Contract DE-AC02-98CH10866,EOLEOLand the Laboratory Directed Research and Development program at theEOLEOLBrookhaven National Laboratory (BNL). BNL is operated for the DOE byEOLEOLBattelle Memorial Institute. Jason Olfert also acknowledges partialEOLEOLsupport from the Goldhaber Distinguished Fellowship from BrookhavenEOLEOLScience Associates. The authors also wish to acknowledge Dr. PeterEOLEOLTakacs for his help with the optics on the FIMS.},
ga = {370OZ},
j9 = {AEROSOL SCI TECH},
ji = {Aerosol Sci. Technol.},
keywords = {INTEGRATED MOBILITY SPECTROMETER; REAL-TIME MEASUREMENT},
la = {English},
nr = {12},
owner = {jolfert},
pa = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA},
pg = {15},
pi = {PHILADELPHIA},
publisher = {Taylor \& Francis Inc},
rp = {Wang, J, Brookhaven Natl Lab, Dept Sci, Upton, NY 11973 USA.},
sc = {Engineering, Mechanical; Environmental Sciences},
sn = {0278-6826},
tc = {0},
timestamp = {2009.05.13},
ut = {ISI:000260772800001}
}
@article{Quiros2015,
title = {Particle effective density and mass during steady-state operation of {GDI}, {PFI}, and diesel passenger cars.},
author = {D Quiros and Shaohua Hu and Shishan Hu and E Lee and S Sardar and X Wang and J Olfert and H Jung and Y Zhu and T Huai},
journal = {Journal of Aerosol Science},
year = {2015},
pages = {39--54},
volume = {83},
abstract = {Particle effective density is an important physical property of vehicle exhaust, and is required for estimating particulate matter (PM) mass emissions using the Integrated Particle Size Distribution (IPSD) method. In this study, we measure particle effective density of five light-duty vehicles with PM emissions below the Low Emission Vehicle (LEV) III PM standards of 1 or 3 mg/mi (0.62 and 1.86 mg/km) using the Differential Mobility Analyzer (DMA) – Centrifugal Particle Mass Analyzer (CPMA) approach. Test vehicles included two gasoline direct injection (GDI) vehicles without particulate filters, and for the first time reported in the literature, two port-fuel injected (PFI) vehicles and a turbocharged direct injection (TDI) light-duty diesel vehicle with a diesel particulate filter (DPF). The particle effective density functions generally resemble previous work on GDI and diesel engines without particulate filters but, for many size ranges, the PFI and TDI vehicles produced emissions with higher particle effective densities than GDI vehicles. Good linear correlation was found between the gravimetric and IPSD methods when applying the new particle effective density functions to size distribution measured by the TSI Engine Exhaust Particle Sizer (EEPS, 5.6–560 nm, R2=0.84); however, the IPSD method underestimated gravimetric mass by 64%. When using a TSI Aerodynamic Particle Sizer (APS, 0.54–2.5 µm) to measure the contribution of larger particles, underestimation bias was virtually eliminated and the correlation improved dramatically (R2=0.96). Even stronger correlation between IPSD and gravimetric methods was achieved when using a Scanning Mobility Particle Sizer (SMPS, 8.7–365 nm) and the APS (R2=0.97). A procedure for correcting EEPS measurements using the SMPS is presented and evaluated.},
doi = {10.1016/j.jaerosci.2014.12.004},
owner = {jolfert},
timestamp = {2014.12.31}
}
@article{Schnitzler2014,
title = {Soot aggregate restructuring due to coatings of secondary organic aerosols derived from aromatic precursors},
author = {E Schnitzler and A Dutt and A Charbonneau and J Olfert and W Jaeger},
journal = {Environmental Science \& Technology},
year = {2014},
pages = {14309--14316},
volume = {48},
abstract = {Restructuring of monodisperse soot aggregates due to coatings of secondary organic aerosol (SOA) derived from hydroxyl radical-initiated oxidation of toluene, p-xylene, ethylbenzene, and benzene was investigated in a series of photo-oxidation (smog) chamber experiments. Soot aggregates were generated by combustion of ethylene using a McKenna burner, treated by denuding, size-selected by a differential mobility analyzer, and injected into a smog chamber, where they were exposed to low vapor pressure products of aromatic hydrocarbon oxidation, which formed SOA coatings. Aggregate restructuring began once a threshold coating mass was reached, and the degree of the subsequent restructuring increased with mass growth factor. Although significantly compacted, fully processed aggregates were not spherical, with a mass-mobility exponent of 2.78, so additional SOA was required to fill indentations between collapsed branches of the restructured aggregates before the dynamic shape factor of coated particles approached 1. Trends in diameter growth factor, effective density, and dynamic shape factor with increasing mass growth factor indicate distinct stages in soot aggregate processing by SOA coatings. The final degree and coating mass dependence of soot restructuring were found to be the same for SOA coatings from all four aromatic precursors, indicating that the surface tensions of the SOA coatings are similar.},
doi = {10.1021/es503699b},
owner = {jolfert},
timestamp = {2014.08.14}
}
@article{SchwarzJP2010,
title = {The detection efficiency of the single particle soot photometer},
author = {Schwarz,J. P. and Spackman,J. R. and Gao,R. S. and Perring,A. E. and Cross,E. and Onasch,T. B. and Ahern,A. and Wrobel,W. and Davidovits,P. and Olfert,J. and Dubey,M. K. and Mazzoleni,C. and Fahey,D. W.},
journal = {Aerosol Science and Technology},
year = {2010},
number = {8},
pages = {612-628},
volume = {44},
abstract = {A single particle soot photometer (SP2) uses an intense laser to heat individual aerosol particles of refractory black carbon (rBC) to vaporization, causing them to emit detectable amounts of thermal radiation that are used to quantify rBC mass. This approach is well suited for the detection of the majority of rBC mass loading in the ambient atmosphere, which occurs primarily in the accumulation mode ( 1?300 fg-rBC/particle). In addition to operator choices about instrument parameters, SP2 detection of rBC number and/or mass can be limited by the physical process inherent in the SP2 detection technique ? namely at small rBC mass or low laser intensities, particles fail to heat to vaporization, a requirement for proper detection. In this study, the SP2's ability to correctly detect and count individual flame-generated soot particles was measured at different laser intensities for different rBC particle masses. The flame-generated soot aerosol used for testing was optionally prepared with coatings of organic and non-organic material and/or thermally denuded. These data are used to identify a minimum laser intensity for accurate detection at sea level of total rBC mass in the accumulation mode (300 nW/(220-nm PSL)), a minimum rBC mass ( 0.7-fg rBC-mass corresponding to 90 nm volume-equivalent diameter) for near-unity number detection efficiency with a typical operating laser intensity (450 nW/(220-nm PSL)), and a methodology using observed color temperature to recognize laser intensity insufficient for accurate rBC mass detection. Additionally, methods for measurement of laser intensity using either laboratory or ambient aerosol are presented.},
doi = {10.1080/02786826.2010.481298}
}
@article{Symonds2013,
title = {The {CPMA}-Electrometer System --- {A} Suspended Particle Mass Concentration Standard},
author = {Symonds, Jonathan P. R. and Reavell, Kingsley St.J. and Olfert, Jason S.},
journal = {Aerosol Science and Technology},
year = {2013},
number = {8},
pages = {i-iv},
volume = {47},
doi = {10.1080/02786826.2013.801547},
owner = {jolfert},
timestamp = {2013.06.05}
}
@article{SymondsJPR01,
title = {Diesel soot mass calculation in real-time with a differential mobility spectrometer},
author = {J. P. R. Symonds and K. St. J. Reavell and J. S. Olfert and B. W. Campell and S. J. Swift},
journal = {Journal of Aerosol Science},
year = {2007},
pages = {52--68},
volume = {38},
abstract = {This paper presents a methodology to allow a real-time particle size spectrometer to produce a mass concentration output by calculation from its electrical mobility response. As part of this, a Bayesian statistical algorithm for parametrising spectral data from the Cambustion DMS500 in terms of a number of lognormal functions is outlined, allowing the nucleation and accumulation modes of a Diesel aerosol to be treated separately and also to reduce mass calculation noise and improve spectral resolution. Previous literature is combined with new experimental results to develop a size:mass power-law relationship for this instrument. The effective density as a function of size for this instrument is found to be closer to that for water droplets than equivalent relationships for DMA/SMPS measurements in the literature, therefore making DMS500 mass calculation less susceptible to error from liquid adsorbed on agglomerates. The technique is validated with two Diesel engines against the gravimetric methods of filter paper and Diesel particulate filter (DPF) weighings. Good agreement is achieved over a variety of engine conditions, with the mean and standard deviation of the percentage difference of the calculated mass concentration from DPF weighings being - 12.1 +/- 11.4 % and from filter paper weighings being - 15.1 +/- 18.0 %. The calculated mass concentrations are systematically below those of the gravimetric methods.},
doi = {10.1016/j.jaerosci.2006.10.001}
}
@article{TavakoliF2011,
title = {Aerosol penetration in microchannels},
author = {Tavakoli,F. and Mitra,S. K. and Olfert,J. S.},
journal = {Journal of Aerosol Science},
year = {2011},
number = {5},
pages = {321-328},
volume = {42},
abstract = {New applications involving aerosol transport in microscale configurations requires the derivation of the penetration efficiency of aerosols in microchannels. Although many analytical solutions for the aerosol penetration in channels have been investigated, none of them are applicable for microchannels. Previously, the no-slip condition for the gas velocity and the zero particle concentration boundary condition have been applied to the convection diffusion equation. However, recent studies show these boundary conditions may not be appropriate for microscale geometries. The particle penetration through rectangular microchannels and cylindrical microtubes has been obtained using the numerical Crank Nicolson method with slip flow at the walls. Existing correlations for the aerosol penetration have been modified for the slip flow regime based on an optimization method. These correlations give the penetration as a function of the dimensionless deposition factor and Knudsen number of the gas. At large Knudsen numbers the penetration decreases relative to the case with continuum flow. Therefore, the aerosol penetration decreases in the slip flow regime. However, the non-zero boundary condition for the particle concentration at the walls does not have any significant effect on the model results of the particle penetration.},
doi = {10.1016/j.jaerosci.2011.02.007}
}
@article{Tavakoli2014a,
title = {Determination of particle mass, effective density, mass-mobility exponent, and dynamic shape factor using an aerodynamic aerosol classifier and a differential mobility analyzer in tandem},
author = {Farzan Tavakoli and Jason S. Olfert},
journal = {Journal of Aerosol Science},
year = {2014},
pages = {35--42},
volume = {75},
doi = {10.1016/j.jaerosci.2014.04.010},
owner = {jolfert},
timestamp = {2014.04.25}
}
@article{Tavakoli2013,
title = {An Instrument for the Classification of Aerosols by Particle Relaxation Time: {T}heoretical Models of the Aerodynamic Aerosol Classifier},
author = {Tavakoli, F. and Olfert, J. S.},
journal = {Aerosol Science and Technology},
year = {2013},
number = {8},
pages = {916-926},
volume = {47},
abstract = {A new aerosol particle classifier, the aerodynamic aerosol classifier (AAC), is presented and its classifying characteristics are determined theoretically. The AAC consists of two rotating coaxial cylinders rotating at the same angular velocity. The aerosol to be classified enters through a gap in the inner cylinder and is carried axially by particle-free sheath flow. The centrifugal force causes the particles between the rotating cylinders to move in the radial direction and particles of a narrow range of particle relaxation times exit the classifier through a gap in the outer cylinder with the sample flow. Particles with larger relaxation times impact and adhere to the outer cylinder and particles with smaller relaxation times exit the classifier with the exhaust flow. Thus, the aerosol is classified by particle relaxation time from which the aerodynamic equivalent diameter can easily be found. Four theoretical models of the instrument transfer function are developed. Analytical particle streamline models (with and without the effects of particle diffusion), like those often used for mobility classifiers, are developed for the case when the centrifugal acceleration field is assumed to be uniform in the radial direction. More accurate models are developed when this assumption is not made. These models are the analytical limiting trajectory model which neglects the effects of diffusion and a numerical convective diffusion model that does not. It is shown that these models agree quite well when the gap between the cylinders is small compared to the radii of the cylinders. The models show that, theoretically, the AAC has a relatively wide classification range and high resolution. Copyright 2013 American Association for Aerosol Research},
doi = {10.1080/02786826.2013.802761},
owner = {jolfert},
timestamp = {2013.06.05}
}
@article{Tavakoli2014,
title = {Generation of a Monodisperse Size-Classified Aerosol Independent of Particle Charge},
author = {Tavakoli, Farzan and Symonds, Jonathan P. R. and Olfert, Jason S.},
journal = {Aerosol Science and Technology},
year = {2014},
number = {3},
pages = {i-iv},
volume = {48},
doi = {10.1080/02786826.2013.877121}
}
@article{TITOSKY2014,
title = {The Effect of Altitude on Inhaler Performance},
author = {Jordan T. F. Titosky and Chelsea M. D. Morin and Jonathan D. Suderman and Jason S. Olfert and Warren H. Finlay and Reinhard Vehring},
journal = {Journal of Pharmaceutical Sciences},
year = {2014},
pages = {2116--2124},
volume = {103},
abstract = {The purpose of the study is to understand the effect of altitude on the performance of selected pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). A testing apparatus that created consistent breath profiles through the Alberta Idealized Throat was designed to test five pMDIs and two DPIs at altitudes of 670, 2450, 3260, and 4300 m. Both gravimetric and chemical assays were conducted to determine the in vitro lung dose. Additionally, spray duration and shot weight for pMDIs and device resistance for DPI were measured. There was no significant change in in vitro lung dose for any of the pMDIs tested. Shot weight and spray duration were unaffected. The device resistance of the DPIs decreased with increasing altitude and was successfully modeled as a function of ambient pressure. The in vitro lung dose of both DPIs showed no significant change when operated with an inhaler pressure drop of 4 kPa, but for the Bricanyl Turbuhaler, a significant decrease occurred when matching the volumetric inspiratory flow rate to that of the baseline altitude.},
doi = {10.1002/jps.24032},
owner = {jolfert},
timestamp = {2014.06.03}
}
@article{acp-18-17819-2018,
title = {Principal component analysis of summertime ground site measurements in the Athabasca oil sands with a focus on analytically unresolved intermediate-volatility organic compounds},
author = {Tokarek, T. W. and Odame-Ankrah, C. A. and Huo, J. A. and McLaren, R. and Lee, A. K. Y. and Adam, M. G. and Willis, M. D. and Abbatt, J. P. D. and Mihele, C. and Darlington, A. and Mittermeier, R. L. and Strawbridge, K. and Hayden, K. L. and Olfert, J. S. and Schnitzler, E. G. and Brownsey, D. K. and Assad, F. V. and Wentworth, G. R. and Tevlin, A. G. and Worthy, D. E. J. and Li, S.-M. and Liggio, J. and Brook, J. R. and Osthoff, H. D.},
journal = {Atmospheric Chemistry and Physics},
year = {2018},
number = {24},
pages = {17819--17841},
volume = {18},
doi = {10.5194/acp-18-17819-2018}
}
@article{Kazemimanesh2019,
author = {Mohsen Kazemimanesh and Alireza Moallemi and Kevin Thomson and Greg Smallwood and Prem Lobo and Jason S. Olfert},
title = {A novel miniature inverted-flame burner for the generation of soot nanoparticles},
doi = {10.1080/02786826.2018.1556774},
number = {2},
pages = {184-195},
volume = {53},
abstract = {AbstractLab-scale soot nanoparticle generators are used by the aerosol research community to study the properties of soot over a broad range of particle size distributions, and number and mass concentrations. In this study, a novel miniature inverted-flame burner is presented and its emitted soot particles were characterized. The burner consisted of two co-annular tubes for fuel and co-flow air and the flame was enclosed by the latter. The fuel used was ethylene. A scanning mobility particle sizer (SMPS) and an aerodynamic aerosol classifier (AAC) were used to measure mobility and aerodynamic size distribution of soot particles, respectively. Particle morphology was studied using transmission electron microscopy (TEM). The elemental carbon (EC) and organic carbon (OC) content of the soot were measured using thermal-optical analysis (TOA). The burner produced soot particles with mobility diameter range of 66Ð270?nm, aerodynamic diameter range of 56Ð140?nm, and total concentration range of 2e5 Ð 1?e7?cm?3. TEM images showed that most soot particles were sub-micron soot aggregates. Some soot superaggregates, typically larger than 2?µm in length, were observed and their abundance increased with ethylene flow rate. TOA showed that the concentration of EC in the generated soot increased with ethylene flow rate, and the soot was observed to have high EC fraction at high ethylene flow rates. The miniature inverted-flame burner was demonstrated to produce soot nanoparticles over a range of concentrations and sizes with high EC content, making it a practical device to study soot nanoparticle properties in different applications.},
journal = {Aerosol Science and Technology},
publisher = {Taylor \& Francis},
year = {2019}
}
@article{Kazemimanesh2019a,
author = {Mohsen Kazemimanesh and Ramin Dastanpour and Alberto Baldelli and Alireza Moallemi and Kevin A. Thomson and Melina A. Jefferson and Matthew R. Johnson and Steven N. Rogak and Jason S. Olfert},
title = {Size, effective density, morphology, and nano-structure of soot particles generated from buoyant turbulent diffusion flames},
journal = {Journal of Aerosol Science},
year = {2019},
volume = {132},
pages = {22 - 31},
doi = {10.1016/j.jaerosci.2019.03.005},
abstract = {With a global gas flaring volume of ?140 billion cubic meters, flares are an important source of particulate emissions; however, very little is known about the physical and morphological properties of these particle emissions. To study these properties, a laboratory pipe flare producing a buoyant turbulent diffusion flame was used which allowed controlled experiments on flames up to ?3?m tall. Three flare diameters (38.1, 50.8, and 76.2?mm) were used in this study with fuel exit velocities of 0.5, 0.9, and 1.5?m/s. ÔLightÕ, ÔmediumÕ, and ÔheavyÕ fuel compositions (consisting of C1 to C4 alkanes, carbon dioxide, and nitrogen in concentration representative of flares in the Alberta, Canada upstream oil and gas sector) were used, where heavier compositions refer to a greater concentration of higher order alkanes. Size distributions of soot particles were measured using a scanning mobility particle sizer. Mass-mobility relationship and effective density of particles were determined using a tandem arrangement of a differential mobility analyzer, a centrifugal particle mass analyzer and a condensation particle counter. Morphology and nano-structure of the particles were studied using transmission electron microscopy and Raman spectroscopy, respectively. Results showed that the particle median diameter and concentration increased as the fuel composition was changed from light to medium to heavy. On the other hand, particle morphology, measured by the relationships between particle mass vs. mobility (or effective density) and primary particle size vs. particle aggregate size, was independent of fuel composition, flow rate, or flare size and was in good agreement with previously reported values for that of soot particles from different internal combustion engines. Previously developed relations between effective density and primary particle size work well for the soot particles of this study. Raman spectroscopy indicated slightly lower D1/G ratios (more graphitic content) for the heavier fuels.},
keywords = {Flare, Black carbon, Morphology, Particle size distribution, Effective density, Raman spectroscopy}
}
@article{Olfert2019,
author = {Jason Olfert and Steven Rogak},
title = {Universal relations between soot effective density and primary particle size for common combustion sources},
journal = {Aerosol Science and Technology},
year = {2019},
volume = {53},
number = {5},
pages = {485-492},
note = {One of 13 papers selected as a "notable paper" in 2019 by the Aerosol Science \& Technology Editors.},
doi = {10.1080/02786826.2019.1577949},
publisher = {Taylor \& Francis}
}
@article{Titosky2019,
author = {Jordan Titosky and Ali Momenimovahed and Joel Corbin and Kevin Thomson and Greg Smallwood and Jason S. Olfert},
title = {Repeatability and intermediate precision of a mass concentration calibration system},
doi = {10.1080/02786826.2019.1592103},
number = {6},
pages = {701-711},
volume = {53},
abstract = {Many aerosol instruments require calibration to make accurate measurements. A centrifugal particle mass analyzer (CPMA) and aerosol electrometer can be used to calibrate aerosol instruments that measure mass concentration. To understand the sources of uncertainty in the calibration method, two CPMA-electrometer systems were tested to measure the repeatability and intermediate precision of the system, where the repeatability is the standard deviation of several measurements using the same system over a short period of time, and the intermediate precision is the standard deviation of several measurements using different instruments with different calibrations over a long period of time. It was found that the repeatability of the CPMA and the aerosol electrometer were both 0.8\%, while the intermediate precision was 1.3\% and 2.2\%, respectively. The intermediate precision of the aerosol electrometers determined here compares well with a broader study by national metrology institutes which determined an intermediate precision of \~1.7\%. By propagation of uncertainty, it is expected that a CPMA-electrometer system would have repeatability of 1.1\% and an intermediate precision of \~2.1\%. This compares favorably to thermal-optical analysis methods which aim to measure black carbon mass concentrations for instrument calibration, which have a repeatability in the range of 8.5Ð20\% and reproducibility in the range of 20Ð26\% for elemental carbon. Thus, the CPMA-electrometer method may be a good alternative to existing instrument calibration procedures.},
journal = {Aerosol Science and Technology},
year = {2019}
}
@article{MOALLEMI201946,
author = {Alireza Moallemi and Mohsen Kazemimanesh and Joel C. Corbin and Kevin Thomson and Greg Smallwood and Jason S. Olfert and Prem Lobo},
title = {Characterization of black carbon particles generated by a propane-fueled miniature inverted soot generator},
journal = {Journal of Aerosol Science},
year = {2019},
volume = {135},
pages = {46 - 57},
doi = {10.1016/j.jaerosci.2019.05.004},
abstract = {The miniature inverted soot generator is a novel soot particle generator, capable of producing black carbon (BC) particles with a wide range of properties. The main advantages of this device are its portability, simplicity, low fuel consumption, and relatively low cost compared to other soot generators. In this study, the performance of the miniature inverted soot generator was evaluated using propane as the fuel over a range of air and fuel flow rates. The stability and repeatability of the soot generator to produce BC particles of controlled size distribution, and number and mass concentration was demonstrated. Furthermore, optical absorption, single scattering albedo (SSA), and elemental carbon (EC) and organic carbon (OC) concentrations of the generated particles were measured. When fueled with propane, the miniature inverted soot generator was capable of repeatedly generating particles with average mode mobility diameter ranging from 140?nm to 200?nm, number concentrations ?4???106Ð?2.7???107 #/cm3, and mass concentrations ?8Ð?140?mg/m3. For many of the investigated operating conditions, the elemental to total carbon ratio (EC/TC) of the generated soot particles was greater than 90\%. The mass absorption cross section of generated particles ranged from 3 to 5?m2/g at a wavelength of 870?nm. The results obtained from this study indicate that the miniature inverted soot generator is ideal for producing BC particles with high EC fraction, which can be used as calibration aerosol for BC diagnostic instruments.},
keywords = {Soot generator, Inverted flame, Black carbon, Calibration aerosol, Thermal-optical analysis, Mass absorption cross section}
}
@article{SANGNOURPOUR2019,
author = {Nafiseh Sang-Nourpour and Jason S. Olfert},
title = {Calibration of optical particle counters with an aerodynamic aerosol classifier},
journal = {Journal of Aerosol Science},
year = {2019},
volume = {138},
pages = {105452},
doi = {10.1016/j.jaerosci.2019.105452},
abstract = {A new technique to calibrate the sizing and counting characteristics of single-particle optical particle counters (OPCs) is presented. The method is not limited to a specific material for calibration, rather any material that can be aerosolized may be used for calibration. Examples of aerosols with real and complex refractive indices and spherical and non-spherical shapes are employed to demonstrate this calibration approach. The material choices include bis(2-ethylhexyl) sebacate, Fomblin, and soot. To generate monodisperse aerosols, an aerodynamic aerosol classifier is employed along with a constant output atomizer and a miniature inverted soot generator. The optical particle counter is then coupled to a condensation particle counter that facilitates concentration comparisons between the two devices. This approach is useful for OPC calibration for particle sizes less than approximately 5?um.},
keywords = {Optical particle counter, Calibration, Aerodynamic aerosol classifier, and condensation particle counter}
}
@article{SIPKENS2020105484,
author = {T.A. Sipkens and J.S. Olfert and S.N. Rogak},
title = {Inversion methods to determine two-dimensional aerosol mass-mobility distributions: A critical comparison of established methods},
journal = {Journal of Aerosol Science},
year = {2020},
volume = {140},
pages = {105484},
doi = {10.1016/j.jaerosci.2019.105484},
abstract = {This paper provides a critical review of methods used to invert tandem measurements to determine the two-dimensional distribution of particle mass and mobility. We consider the performance of weighted least-squares analysis, Twomey-type approaches, a maximum entropy method, Tikhonov regularization (over a range of regularization parameters), and statistical inversion. A detailed analysis is performed on a bimodal phantom to demonstrate the typical characteristics of reconstructions resulting from the different inversion techniques, before the Euclidean error between the phantom and reconstructions are evaluated for a wider range of phantoms. It is found that 1st order Tikhonov regularization generally outperforms the other established inversion methods, even for narrow phantoms, where the finite representation of the mass-mobility distribution becomes a larger contributor to reconstruction accuracy. Twomey-type approaches, while not as robust, are shown to be an acceptable alternative.},
keywords = {Tandem measurements, CPMA, DMA, Particle size distribution, Data inversion, Mass-mobility distribution}
}
@article{Sipkens2020,
author = {Timothy A. Sipkens and Jason S. Olfert and Steven N. Rogak},
title = {New approaches to calculate the transfer function of particle mass analyzers},
doi = {10.1080/02786826.2019.1680794},
number = {1},
pages = {111-127},
volume = {54},
abstract = {This article provides an overview of methods to evaluate transfer functions for the Couette centrifugal particle mass analyzer (CPMA) and aerosol particle mass analyzer (APM). The work first considers finite difference approaches to solving the partial differential equation governing particle motion, which represents an accurate but computationally-demanding approach to evaluating the transfer function. This is used as a baseline to compare to particle tracking methods, which have been shown to yield closed form expressions for the transfer function. In this work, we extend on previous treatments by presenting a generalized framework that allows us to consider a range of representations of the particle migration velocity. As a result, we derive new closed form expressions for the exact representation of the particle migration velocity under APM conditions and provide significant improvements in the accuracy of the transfer function for CPMA conditions. In the latter case, for a CPMA, particle migration effects dominate, which makes the transfer function easier to approximate. We also show that Taylor series approximations to the particle migration velocity should be taken about the centerline radius rather than the equilibrium radius as was done previously. We end by extending the particle tracking approach and derive new closed form expressions for the transfer function that include diffusion. Copyright © 2019 American Association for Aerosol Research},
journal = {Aerosol Science and Technology},
publisher = {Taylor \& Francis},
year = {2020}
}
@article{JOHNSON2020105526,
author = {Tyler J. Johnson and Robert T. Nishida and Martin Irwin and Jonathan P.R. Symonds and Jason S. Olfert and Adam M. Boies},
title = {Measuring the bipolar charge distribution of nanoparticles: Review of methodologies and development using the Aerodynamic Aerosol Classifier},
journal = {Journal of Aerosol Science},
year = {2020},
volume = {143},
pages = {105526},
doi = {10.1016/j.jaerosci.2020.105526},
abstract = {A review of methodologies to measure the bipolar charge distribution of nanoparticles is completed, including their advantages/disadvantages and sequential development. This summary also provides context for a new development, which uses an Aerodynamic Aerosol Classifier (AAC) and Differential Mobility Analyzer (DMA) in tandem for a similar purpose. It is demonstrated that the tandem AAC-DMA system overcomes some significant limitations of the previous methodologies, such as multiply-charged particle artefacts and low measurement signals. The tandem AAC-DMA methodology also has the sensitivity to detect other charging phenomena, such as the effects of different sample flow rates through the charger, free-ions downstream of the charger, the inlet insert on the 85Kr charger and different particle chargers (x-ray, old 85Kr and new 85Kr). The charge fractions of the particles at low-flow (0.6 L/min) through the new 85Kr charger agreed well (average absolute difference of 0.007) with widely-used charging theory. However, significant deviations from theory (up to a 0.044 difference in charge fractions) were found with a higher sample flow rate (1.2 L/min), with different exposure times to free-ions downstream of the charger, or with the inlet insert on the new 85Kr charger. It was found that regardless of flow rate, a soft x-ray charger resulted in charge fractions which deviated significantly from theory (up to a 0.084 difference in charge fractions), producing higher fractions of positively charged particles and lower fractions of negatively charged particles relative to theory. All of these deviations are likely due to the simplifying assumptions made by the charging theory. Therefore, rigorous measurement of particle charge distributions are necessary for accurate aerosol characterization, such as standard SMPS measurements.},
keywords = {Charge distribution, Bipolar, Aerodynamic Aerosol Classifier, Instrumentation methodologies}
}
@article{amt-13-1129-2020,
author = {Davis, Z. Y. W. and Frie{\ss}, U. and Strawbridge, K. B. and Aggarwaal, M. and Baray, S. and Schnitzler, E. G. and Lobo, A. and Fioletov, V. E. and Abboud, I. and McLinden, C. A. and Whiteway, J. and Willis, M. D. and Lee, A. K. Y. and Brook, J. and Olfert, J. and O'Brien, J. and Staebler, R. and Osthoff, H. D. and Mihele, C. and McLaren, R.},
title = {Validation of {MAX-DOAS} retrievals of aerosol extinction, {SO}$_2$, and {NO}$_2$ through comparison with lidar, sun photometer, active {DOAS}, and aircraft measurements in the {A}thabasca oil sands region},
doi = {10.5194/amt-13-1129-2020},
number = {3},
pages = {1129--1155},
volume = {13},
journal = {Atmospheric Measurement Techniques},
year = {2020}
}
@article{acp-20-3645-2020,
author = {Yu, C. and Liu, D. and Broda, K. and Joshi, R. and Olfert, J. and Sun, Y. and Fu, P. and Coe, H. and Allan, J. D.},
title = {Characterising mass-resolved mixing state of black carbon in {B}eijing using a morphology-independent measurement method},
doi = {10.5194/acp-20-3645-2020},
number = {6},
pages = {3645--3661},
volume = {20},
journal = {Atmospheric Chemistry and Physics},
year = {2020}
}
@article{Adam2020,
author = {Frank Adam and Jason Olfert and Ka-Fai Wong and Susanne Kunert and Joerg Michael Richter},
title = {Effect of Engine-Out Soot Emissions and the Frequency of Regeneration on Gasoline Particulate Filter Efficiency},
doi = {10.4271/2020-01-1431},
note = {2020-01-1431},
journal = {SAE Technical Paper},
year = {2020}
}
@article{Graves2020,
author = {Brian M. Graves and Tyler J. Johnson and Robert T. Nishida and Ryan P. Dias and Benjamin Savareear and James J. Harynuk and Mohsen Kazemimanesh and Jason S. Olfert and Adam M. Boies},
title = {Comprehensive characterization of mainstream marijuana and tobacco smoke},
doi = {10.1038/s41598-020-63120-6},
pages = {7160},
volume = {10},
journal = {Scientific Reports},
year = {2020}
}
@article{SIPKENS2020105565,
author = {T.A. Sipkens and J.S. Olfert and S.N. Rogak},
title = {Inversion methods to determine two-dimensional aerosol mass-mobility distributions {II}: {E}xisting and novel Bayesian methods},
doi = {10.1016/j.jaerosci.2020.105565},
pages = {105565},
volume = {146},
abstract = {Moving towards two-dimensional distributions of particle properties is important to the study of aerosol formation, aerosol climate impacts, and aerosols in material science. This paper builds on existing work to examine Bayesian or statistical approaches to inverting tandem particle mass analyzer (PMA) and differential mobility analyzer (DMA) data to retrieve the two-dimensional mass-mobility distribution. We first consider the Bayesian representation of derivative-based Tikhonov regularization, focusing on the first-order case. We demonstrate a new Bayesian model selection scheme to choose the regularization parameter, which generally outperforms the L-curve approach for derivative-based Tikhonov regularization. We also perform a Bayesian-based uncertainty analysis to evaluate the quality of the reconstructions, noting that uncertainties are lowest in regions close to device setpoints. We then present a new exponential distance prior, a variant of generalized Tikhonov regularization that provides a natural approach to regularizing the two-dimensional aerosol size distribution problem by allowing smoothing preferentially along the length of the distribution. The exponential distance approach is observed to reduce errors in the reconstructions by up to 60%, with the benefit to using the exponential distance prior increasing as the distributions become increasingly narrow, i.e. more highly correlated. Finally, Bayesian model selection is shown to also be a good candidate to optimize the regularization parameters in the exponential distance prior.},
journal = {Journal of Aerosol Science},
keywords = {Aerosol morphology, Particle size distribution, Mass-mobility distribution, Bayesian analysis, Statistical inversion},
year = {2020}
}
@article{KAZEMIMANESH2020168,
author = {Mohsen Kazemimanesh and Chen Kuang and Larry W. Kostiuk and Jason S. Olfert},
title = {Effect of sodium chloride on the evolution of size, mixing state, and light absorption of soot particles from a smoking laminar diffusion flame},
doi = {10.1016/j.combustflame.2020.04.001},
pages = {168 - 178},
volume = {218},
abstract = {In this study, the effect of sodium chloride (NaCl) on the evolution of size, mixing state, and optical properties of particle emissions was investigated. A smoking laminar diffusion flame of methane with flame length of ~100 mm was used, with and without NaCl particles introduced into the fuel stream. Extractive probe sampling with high dilution was used to sample particles and characterize their size and mixing state. Particle size distribution results showed that for the methane-only flame, the soot particles underwent typical processes of formation and coagulation in the flame, partial oxidation near the flame tip, and further coagulation in the post-flame region. In the case of the methaneÐNaCl flame, the coagulation rate between soot particles decreased in the agglomeration region of the flame, resulting in smaller soot particles with higher number concentration. Near the open tip of the flame, the NaCl inhibited soot oxidation, leading to larger particles compared to the methane-only flame due to continued coagulation and reduced oxidation of soot particles. In the post-flame region, where the temperature was sufficiently low, NaCl particles nucleated from its vapour phase, which was a distinct mode from that of soot in the particle size distributions. Electron microscopy images showed that these nucleated NaCl particles were mostly externally mixed and occasionally internally mixed with soot particles. Thermal-optical analysis of emissions sampled from post-flame region showed that the mass concentration of elemental carbon increased by a factor of ~3 when NaCl was added to the flame. However, addition of NaCl did not affect the mass-specific absorption coefficient of particle emissions, which was within previously reported values in the literature.},
journal = {Combustion and Flame},
keywords = {Particle size distribution, Soot mixing state, Soot optical properties, Alkali metal additive, Soot oxidation, Probe sampling},
year = {2020}
}
@article{Tran2020,
author = {Tran, Steven and Brown, Anthony and Olfert, Jason S.},
title = {Comparison of Particle Number Emissions from In-Flight Aircraft Fueled with {J}et {A1}, {JP}-5 and an Alcohol-to-Jet Fuel Blend},
doi = {10.1021/acs.energyfuels.0c00260},
number = {6},
pages = {7218-7222},
volume = {34},
abstract = {The aviation sector has begun to adopt alternative fuels in an effort to reduce net greenhouse gas (GHG) emissions and reduce their impact on climate change. While many lab and flight-based studies have been completed for hydro-treated esters and fatty acids (HEFA) and FischerÐTropsch (FT) alternative fuels, only one lab study has been conducted on alcohol-to-jet synthetic paraffinic kerosene (ATJ-SPK) fuels. Here we report results from the Civil Aviation Alternate Fuels Contrails and Emissions with high blend Biojet (CAAFCEB) project which was conducted in order to gather in-flight emissions data and compare an ethanol-based ATJ-SPK fuel blend and conventional JP-5 fuel to conventional Jet A1 fuel. A research aircraft was flown while fueled with the different fuels and in-flight cruise measurements were made by a second research aircraft gathering emissions and contrail data. In this study we report particle number emission index ratios with effective cutoff diameters of 15 and 7.7 nm for total particles and 13 nm for nonvolatile particles for GE CF700-2D2 engines at cruise. The ATJ-SPK blend was found to significantly reduce total and nonvolatile particle number emissions by up to 97\% compared to Jet A1 fuel, likely due to the much lower aromatic and sulfur content and higher hydrogen content of the fuel. On the other hand, the total particle emissions for the JP-5 were found to have been 4\% smaller than for Jet A1; this small difference is likely due to the similar fuel compositions.},
journal = {Energy \& Fuels},
year = {2020}
}
@article{TRIVANOVIC2020,
author = {Una Trivanovic and Timothy A. Sipkens and Mohsen Kazemimanesh and Alberto Baldelli and A. Melina Jefferson and Bradley M. Conrad and Matthew R. Johnson and Joel C. Corbin and Jason S. Olfert and Steven N. Rogak},
title = {Morphology and size of soot from gas flares as a function of fuel and water addition},
doi = {10.1016/j.fuel.2020.118478},
pages = {118478},
volume = {279},
abstract = {A large-scale, laboratory turbulent diffusion flame was used to study the effects of fuel composition on soot size and morphology. The burner and fuels are typical of those used in the upstream oil and gas industry for gas flaring, a practice commonly used to dispose of excess gaseous hydrocarbons. Fuels were characterized by their carbon-to-hydrogen ratio (from 0.264 to 0.369) and their volumetric higher heating value (HHVv) (from 35.8 to 75.2 MJ/m3). Transmission electron microscopy (TEM) was used to assess primary particle and aggregate size, showing that the scaling of primary particle size to aggregate size was roughly the same for all of the considered fuels (dp = 16.3(da,100 [nm]/100)0.35). However, fuels with higher HHVv produced substantially larger soot aggregates. A scanning mobility particle sizer (SMPS) was also used (i) to measure mobility diameter distributions and (ii) in tandem with a centrifugal particle mass analyzer (CPMA) to determine the two-dimensional mass-mobility and effective density-mobility distributions using a new inversion approach. The new approach was shown to improve internal consistency of inferred morphological parameters, though with a shift relative to median-based analysis of the tandem data. Raman spectroscopy was used to quantify the degree of graphitization in the soot nanostructure. The addition of water to the fuel consistently reduced the soot yields but did not affect other morphological parameters. Larger aggregates also tended to have larger primary particles and higher Raman D/G ratios suggesting larger graphitic domains.},
journal = {Fuel},
keywords = {Soot, Gas flaring, Effective density, Transmission electron microscopy, Primary particle size, Water addition},
year = {2020}
}
@article{Tran2020a,
author = {Steven Tran and Kenjiro Iida and Kumiko Yashiro and Yoshiko Murashima and Hiromu Sakurai and Jason S. Olfert},
title = {Determining the cutoff diameter and counting efficiency of optical particle counters with an aerodynamic aerosol classifier and an inkjet aerosol generator},
doi = {10.1080/02786826.2020.1777252},
number = {11},
pages = {1335--1344},
volume = {54},
abstract = {Abstract A method to determine the cutoff diameter and counting efficiency of single-particle optical particle counters (OPC) is presented. An aerodynamic aerosol classifier (AAC) coupled with an atomizer was used to generate monodisperse dioctyl phthalate particles with a condensation particle counter (CPC) as the reference instrument. This method is accurate for capturing the counting efficiency of OPCs at lower size ranges and determining the cutoff diameter. The CPC was found to be a poor reference instrument for particles larger than 1?µm in which case an inkjet aerosol generator (IAG) was used as the monodisperse particle source and reference instrument. Two different particle materials were used with the IAG: lactose monohydrate and an ionic liquid (1-ethyl-3-methylimidazolium trifluoromethanesulfonate). A combination of the AAC to size smaller particles (<1?µm) and IAG to generate larger particles (>1?µm) was found to provide a comprehensive method capable of covering the counting efficiency over the entire operating range of OPCs. Copyright © 2020 American Association for Aerosol Research},
journal = {Aerosol Science and Technology},
year = {2020}
}
@article{Corbin2020,
author = {Joel C. Corbin and Alireza Moallemi and Fengshan Liu and St\'ephanie Gagn\'e and Jason S. Olfert and Greg J. Smallwood and Prem Lobo},
title = {Closure between particulate matter concentrations measured ex situ by thermal-optical analysis and in situ by the {CPMA}-electrometer reference mass system},
doi = {10.1080/02786826.2020.1788710},
number = {11},
pages = {1293--1309},
volume = {54},
abstract = {Abstract The thermal-optical analysis (TOA) of black carbon in particulate matter (PM) collected on filters has been recommended and used for the calibration of mass-concentration instruments. However, filter-based TOA calibrations have substantial practical limitations, requiring high sample flow rates (>10?litres per minute), long sampling times (up to 3?h), and subsequently manual filter processing with long analysis times (>15?min per filter). These limitations are avoided by in situ calibration techniques such as the centrifugal particle mass analyzer (CPMA)Ðelectrometer reference mass system (CERMS). The CERMS is capable of producing and monitoring in situ reference mass concentrations below 1?µg m?3 and in real-time (\? 1?Hz). Additional advantages of the CERMS are its improved repeatability (1.1\%) over TOA (9Ð11\%), and its measurement of a well-defined quantity: total post-CPMA suspended PM mass. In the present work, we demonstrate closure between these two techniques in terms of PM mass concentration for three different soot generators (viz., the Argonaut miniature inverted soot generator, Jing miniCAST, and National Research Council inverted-flame burner) under carefully controlled conditions. We also demonstrate the sensitivity of the CERMS by characterizing the limits of detection of a commercial laser-induced incandescence instrument and a photoacoustic instrument. Our data support the use of the CERMS with well-characterized PM sources to provide reference mass concentrations for the calibration of instruments measuring PM or black-carbon mass concentration.},
journal = {Aerosol Science and Technology},
publisher = {Taylor & Francis},
year = {2020}
}
@article{Naseri2021,
author = {A. Naseri and T. A. Sipkens and S. N. Rogak and J. S. Olfert},
title = {An improved inversion method for determining two-dimensional mass distributions of non-refractory materials on refractory black carbon},
doi = {10.1080/02786826.2020.1825615},
number = {1},
pages = {104--118},
volume = {55},
abstract = {The present study describes an improved inversion method for determining the two-dimensional mass distribution of non-refractory materials on refractory black carbon using a centrifugal particle mass analyzer (CPMA) and single-particle soot photometer (SP2) system. The novel approach is tested with several well-established regularization methods to determine which method works best in the new method. Contrary to other two-dimensional inversion applications in the literature, in the CPMA-SP2 inversion, there is a physical constraint that the refractory black carbon mass (mrBC) cannot exceed the total particle mass (mP). This constraint has to be considered in the inversion to accommodate the sharp edge where mrBC equals mP which causes established regularization methods to underperform and potentially smooth the distribution over this boundary. This study introduces a novel deconvolution scheme which accommodates the physical constraint and can be solved with various inversion techniques including: least-squares, Twomey, TwomeyÐMarkowski, multiplicative algebraic reconstruction technique (MART), Tikhonov, and exponential distance methods. The new method also accounts for the problem that the mobility of the black carbon particles is unknown but is required for kernel construction, by using an innovative approach based on constraining the inversion so that the marginal distribution from the CPMA-SP2 inversion matches the distribution of dN/dlog?mrBC measured directly by SP2 while the CPMA is bypassed. The inversion technique is tested with synthetic data or ÒphantomsÓ Ð representing uncoated soot, soot coated with non-refactory material, and a mixture of coated and uncoated soot. The results reveal that the exponential distance method outperforms the other regularization methods tested.},
journal = {Aerosol Science and Technology},
year = {2021}
}
@article{Johnson2021,
author = {Tyler J. Johnson and Jonathan P. R. Symonds and Jason S. Olfert and Adam M. Boies},
title = {Accelerated measurements of aerosol size distributions by continuously scanning the aerodynamic aerosol classifier},
doi = {10.1080/02786826.2020.1830941},
number = {2},
pages = {119-141},
volume = {55},
abstract = {AbstractUsing an Aerodynamic Aerosol Classifier (AAC) upstream of a particle detector is a relatively new method for measuring the aerodynamic size distribution of an aerosol. This approach overcomes limitations of previous methodologies by leveraging the high transmission efficiency, independence from particle charging, and adjustable classification range and resolution of the AAC. However, the AAC setpoint must be stepped and stabilized before each measurement, which forces tradeoffs between measurement time and step resolution. This study is the first to develop and validate theory which allows the speed of the AAC classifier to be continuously varied (following an exponential function), rather than stepped. This approach reduces measurement time, while increasing the resolution of the measured distribution. Assuming uniform axial flow, the transfer function of the scanning AAC and its inversion are determined. Limited trajectory theory is used to derive the idealized transfer function of the scanning AAC, while parameterized, particle streamline theory is used to develop the non-idealized transfer function, which accounts for non-idealized particle and flow behaviors within the classifier. This theory and the practical implementation of the scanning AAC are validated by the high agreement of its measurements of polystyrene latex (PSL) particles (within 8.7\% for six sizes between 100?nm to 2.02??m), and of size distributions of three aerosol sources (Bis(2-Ethylhexyl) sebacate, NaCl and soot) to those measured by the stepping AAC (within 2\% or better if the source stability is considered). The validity of assuming uniform axial flow in the classifier and downstream plumbing/detector are also discussed.Copyright 2020 American Association for Aerosol Research},
journal = {Aerosol Science and Technology},
publisher = {Taylor & Francis},
year = {2021}
}
@article{ZAMANI2021119534,
author = {M. Zamani and E. Abbasi-Atibeh and S. Mobaseri and H. Ahsan and A. Ahsan and J.S. Olfert and L.W. Kostiuk},
title = {An experimental study on the carbon conversion efficiency and emission indices of air and steam co-flow diffusion jet flames},
doi = {10.1016/j.fuel.2020.119534},
pages = {119534},
volume = {287},
abstract = {Industrial flaring is a notable global contributor to carbon dioxide emissions and other key pollutants. Introducing a separate assisting fluid near the base of these flames affects their hydrodynamics, thermodynamics, and chemistry, which in turn affects their efficiency and emissions. In this study, a burner constructed of two concentric tubes allowed for various generic burner geometries, where different fuels (methane or propane) and co-flow assisting fluids (air, steam, or inert gases) flowed through the annular space and the center tube, respectively. The effects of the composition and flow rate of the fuel and assisting fluid, as well as the burner head geometry, were investigated in terms of carbon conversion efficiency (CCE) and emission indices of black carbon and oxides of nitrogen. The CCE was observed to be essentially 100% for unassisted flames and remained at that level when assisting fluid, irrespective of composition, was added. However, at some critical flow rate of assisting fluid, the CCE collapsed, and the main flame blew off. In general, the CCE collapse occurred at considerably more mass of air compared to that of steam. Furthermore, adding the assisting fluid co-flow monotonically reduced the black carbon emission by orders of magnitude. On the other hand, the emission of oxides of nitrogen rose slightly with increasing air co-flow flow rate and dropped when steam or other diluents were added. These results showed that there was a range of assisting fluid flow rates, where the CCE was approximately 100%, while the emission of black carbon and nitrogen oxides were highly suppressed.},
journal = {Fuel},
keywords = {Co-flow diffusion flame, Assisted flare, Carbon conversion efficiency, Emission index},
year = {2021}
}
@article{Kazemimanesh2021,
author = {Mohsen Kazemimanesh and Alberto Baldelli and Una Trivanovic and Olga Popovicheva and Mikhail Timofeev and Natalia Shonija and Yuri Obvintsev and Chen Kuang and A. Melina Jefferson and Joel C. Corbin and Greg G. Goss and Daniel S. Alessi and Matthew R. Johnson and Steven N. Rogak and Jason S. Olfert},
title = {Particulate emissions from turbulent diffusion flames with entrained droplets: A laboratory simulation of gas flaring emissions},
doi = {10.1016/j.jaerosci.2021.105807},
pages = {105807},
volume = {157},
abstract = {Global flaring volume exceeds 140 billion m3 annually and flares are a key source of particulate air pollution. During flowback operations subsequent to fracturing of a well, droplets of flowback waterÑwith varying levels of dissolved saltsÑcan be entrained in the flared gas. Despite the widespread prevalence of fracturing, very little is known about the properties of particle emissions from such flares. To study these properties, we used a laboratory pipe flare producing a turbulent diffusion flame without and with entrained droplets. Entrained droplets of deionized water, sodium chloride solution, and solutions representing two typical flowback waters in Canada (Cardium and Duvernay) were used. Three different gas compositions (consisting of C1 to C7 alkanes, carbon dioxide, and nitrogen) representative of flares in the upstream oil and gas sector in Alberta, Canada were studied. The results showed that the salt in the entrained flowback droplets increased the particle concentration by about one order of magnitude by forming freshly nucleated salt particles. Moreover, soot concentration increased as a result of entrained salt. Effective density results showed that small particles (<150Ênm mobility diameter) were mainly salt, while large particles (>300Ênm) were mostly sootÑa result also confirmed by transmission electron microscopy (TEM). Electron micrographs showed that the majority of particles were either individual salt particles or internally-mixed soot-salt particles. The inorganic salt particles mainly consisted of Na and Cl, the two most abundant elements in flowback water. Raman spectroscopy indicated that the salt had much less (or no) impact on graphitic nanostructure of soot, while the fuel blend had a significant effect. The results of this study are significant as they reveal that current emission inventories based on flaring of gases only may underestimate soot emissions from flares with entrained droplets.},
journal = {Journal of Aerosol Science},
keywords = {Gas flaring, Droplets, Flowback water, Produced water, Particulate emissions, Soot},
year = {2021}
}
@article{Bello2021,
author = {Olanrewaju W. Bello and Milad Zamani and Ehsan Abbasi-Atibeh and Larry W. Kostiuk and Jason S. Olfert},
title = {Comparison of emissions from steam- and water-assisted lab-scale flames},
doi = {10.1016/j.fuel.2021.121107},
pages = {121107},
volume = {302},
abstract = {Steam-assisted flares are often used in the downstream oil and gas industries as a strategy to produce ÒsmokelessÓ combustion. The addition of liquid water to flames is also known to suppress soot formation but is rarely done in industrial flares. Since utilizing liquid water saves the energy required to convert water to steam, it was useful to investigate the extent to which liquid water and steam individually affect soot formation and NOx emissions during flaring. The three fuels used in this study were pure propane, pure methane, and a mixture of 90% methane and 10% propane, the latter approximating the typical volumetric higher heating value of Alberta flare gas. The fuel flow rates were fixed at 20 standard L/min in all cases, and liquid water and steam were introduced into the fuel's combustion zone, while their flow rates varied from 0 to 30Êg/min. The results show that both liquid water and steam reduce NOx and soot mass emissions; however, liquid water reduces NOx and soot emissions more than steam. Likewise, the total particle number concentration and the particle sizes decrease with an increase in liquid water and steam. Simultaneously, liquid water reduces the total particle number concentration more than steam at the same assist flow rate, but a slight difference in their particle sizes. The thermodynamic mechanism appears to play the major role in controlling emissions. These results suggest that water-assisted flares in the oil and gas industries would likely produce lower emissions with a lower operating cost than steam-assisted flares.},
journal = {Fuel},
keywords = {Soot suppression, Steam and water assist, Turbulent non-premixed flame, Emission indices, Particle size distribution, NO and soot emissions},
year = {2021}
}
@article{Kong2021,
author = {Kong, Xiangxiao and Chen, Kerry and Greiner, Robert and Votsmeier, Martin and Belot, Igor and Vidal, David and Bertrand, Fran\c{c}ois and Hayes, Robert E. and Olfert, Jason S.},
title = {Particle Size-Dependent Filtration Efficiency and Pressure Drop of Gasoline Particle Filters with Varying Washcoat Volumes},
doi = {10.1007/s40825-021-00193-3},
pages = {105-116},
volume = {7},
abstract = {Gasoline particulate filters (GPFs) are an effective means of reducing particle emissions from gasoline direct injection (GDI) engines. This paper explores the filtration efficiency and pressure drop of three GPFs with varying in-wall washcoat volumes through three parameters: particle size, flow rate of gas through the GPF, and amount of soot accumulation. The three GPFs are tested on a custom filtration efficiency test rig with a miniature inverted soot generator used as a particle source at three space velocities of: 32, 000, 97, 000, and 161, 000Êh?1. A scanning mobility particle sizer (SMPS) is used to measure the filtration efficiency and amount of soot accumulated on the GPF. The GPFs are loaded with soot until the average filtration efficiency reached?>??~?98%. Results show that the filtration efficiency is a function of particle size, soot loading, and space velocity. With increasing soot loading on the GPF, the filtration efficiencies increase significantly and become less sensitive to mobility diameter. Filtration efficiency is generally found to decrease with increasing space velocity. For clean filters, the GPF without washcoat has the same or higher filtration efficiency than the GPFs with washcoat. At high amounts of soot accumulation, the GPFs with a washcoat have the highest filtration efficiency. The coated filters have a much higher rate of filtration efficiency and pressure drop increase compared to the bare filter. The mechanisms leading to the observed trends in filtration efficiency and pressure drop are also discussed.},
journal = {Emission Control Science and Technology},
year = {2021}
}
@article{SIPKENS2021,
author = {Timothy A. Sipkens and Una Trivanovic and Arash Naseri and Olanrewaju W. Bello and Alberto Baldelli and Mohsen Kazemimanesh and Allan K. Bertram and Larry Kostiuk and Joel C. Corbin and Jason S. Olfert and Steven N. Rogak},
title = {Using two-dimensional distributions to inform the mixing state of soot and salt particles produced in gas flares},
doi = {10.1016/j.jaerosci.2021.105826},
pages = {105826},
volume = {158},
abstract = {Gas flaring is a common practice in the oil and gas industry, where droplets of flowback water with varying levels of dissolved salts (mainly composed of sodium and chloride) often become entrained in the flared gas. In this study, we examine the mixing state of the aerosol produced by a laboratory flare with and without entrained droplets of sodium chloride solutions. The resultant aerosol is cross-examined using several different methods, including: transmission electron microscopy (TEM), tandem measurements using a CPMA and a differential mobility analyzer (DMA), tandem measurements using a centrifugal particle mass analyzer (CPMA) and a single particle soot photometer (SP2), and Raman spectroscopy. A focus is placed on two-dimensional distributions of properties and the kind of morphological information contained therein. The TEM and CPMA-SP2 measurements both show that the majority of soot particles were internally mixed with salt, while TEM and CPMA-DMA measurements indicate that there are also a large number of isolated salt particles.},
journal = {Journal of Aerosol Science},
keywords = {Flaring, Soot, Particle morphology, Sodium chloride, Tandem measurements, Mass-mobility distributions},
year = {2021}
}
@article{NASERI2022105897,
author = {A. Naseri and T.A. Sipkens and S.N. Rogak and J.S. Olfert},
title = {Optimized instrument configurations for tandem particle mass analyzer and single particle-soot photometer experiments},
doi = {10.1016/j.jaerosci.2021.105897},
pages = {105897},
volume = {160},
abstract = {Tandem centrifugal particle mass analyzer (CPMA)-single-particle soot photometer (SP2) arrangements provide a measure of the non-refractory components of soot. In such a system, the CPMA is used to classify particles by mass-to-charge ratio (i.e., total particle mass mp), and the SP2 measures the mass of rBC (i.e., mrBC) within each particle. Data inversion can then be used to compute the two-dimensional total particle-non-refractory black carbon (rBC) (mp-mrBC) distribution, mapping out the distribution of non-refractory material on rBC particles. He present study derives the optimum sampling settings (i.e., the number of CPMA setpoints per decade, the number of SP2 bins per decade, CPMA resolution, and the number of SP2 counts per CPMA setpoint) to accurately reconstruct mp-mrBC distributions. Monte Carlo sampling is used to realize the sensitivity of reconstruction error to experimental inputs across a range of distribution widths. General recommendations for a typical aged atmospheric aerosol include: (i) large numbers of SP2 bins per decade (ns' = 64), (ii) a preference for higher SP2 sampling counts per CPMA setpoint (Ns > 104), (iii) a moderate number of CPMA setpoints per decade (ncÕ = 3 to 8), (iv) CPMA resolution around 1.0, and (v) a high CPMA flow rate (1.5 L/min). These settings generally result in reconstruction accuracies below 3\%. These recommendations vary based on the concentration of the aerosol, the time available for the measurement, and the width of the distribution. Optimized CPMA-SP2 settings are presented for example distributions as a function of aerosol concentration and desired measurement time.},
journal = {Journal of Aerosol Science},
keywords = {Tandem measurements, Centrifugal particle mass analyzer (CPMA), Single-particle soot photometer (SP2), Data inversion, 1st order tikhonov regularization},
year = {2022}
}
@article{Chen2022,
author = {Kerry Chen and Robert T. Nishida and Charles Robert Koch and Jason S. Olfert},
title = {Development and testing of a universal aerosol conditioner},
doi = {10.1080/02786826.2022.2030463},
number = {4},
pages = {382--393},
volume = {56},
abstract = {A general purpose aerosol conditioning device called the Universal Aerosol Conditioner (UAC) has been designed and tested. The device may be used to condition an aerosol in multiple ways: dilute the entire aerosol (gas- and particle-phase), dilute only a gas-phase component of the aerosol without diluting the particle concentration, denude the aerosol by removing semi-volatile material from the particle phase, and humidify or dehumidify an aerosol. The UAC accomplishes these processes by bringing the aerosol into contact with sheath air and allowing enough time for gas-phase components of the aerosol to diffuse into the sheath flow. A model was developed to assess the theoretical performance of the UAC and was solved numerically. From the model it was determined that two parameters dictated the rate of diffusion between the two flows: the PŽclet number and the ratio of sheath-to-aerosol flow rates. A prototype was designed and built and the theory of operation was experimentally validated by measuring the particle penetration efficiency and the gas dilution factor at various particle sizes and flow conditions. The results showed that at low aerosol and sheath flows, the prototype behaved closely to the theoretical model but diverged from the theory once the sheath flows were increased, presumably due to mixing between the two flows.},
journal = {Aerosol Science and Technology},
year = {2022}
}
@article{Johnson2022,
author = {Johnson, Tyler J. and Nishida, Robert T. and Sonpar, Ashlesha P. and Lin, Yi-Chan James and Watson, Kimberley A. and Smith, Stephanie W. and Conly, John M. and Evans, David H. and Olfert, Jason S.},
title = {Viral load of {SARS-CoV-2} in droplets and bioaerosols directly captured during breathing, speaking and coughing},
doi = {10.1038/s41598-022-07301-5},
number = {1},
pages = {3484},
volume = {12},
abstract = {Determining the viral load and infectivity of SARS-CoV-2 in macroscopic respiratory droplets, bioaerosols, and other bodily fluids and secretions is important for identifying transmission modes, assessing risks and informing public health guidelines. Here we show that viral load of SARS-CoV-2 Ribonucleic Acid (RNA) in participantsÕ naso-pharyngeal (NP) swabs positively correlated with RNA viral load they emitted in both droplets >10 $$\upmu \hbox {m}$$and bioaerosols <10 $$\upmu \hbox {m}$$directly captured during the combined expiratory activities of breathing, speaking and coughing using a standardized protocol, although the NP swabs had $$\approx$$10$$^3\times$$more RNA on average. By identifying highly-infectious individuals (maximum of 18,000 PFU/mL in NP), we retrieved higher numbers of SARS-CoV-2 RNA gene copies in bioaerosol samples (maximum of 4.8$${\times }10^{5}$$gene copies/mL and minimum cycle threshold of 26.2) relative to other studies. However, all attempts to identify infectious virus in size-segregated droplets and bioaerosols were negative by plaque assay (0 of 58). This outcome is partly attributed to the insufficient amount of viral material in each sample (as indicated by SARS-CoV-2 gene copies) or may indicate no infectious virus was present in such samples, although other possible factors are identified.},
journal = {Scientific Reports},
refid = {Johnson2022},
year = {2022}
}
@article{Wu2022,
author = {Wu, Jing and Chen, Jiawei and Olfert, Jason S. and Zhong, Lexuan},
title = {Filter evaluation and selection for heating, ventilation, and air conditioning systems during and beyond the {COVID}-19 pandemic},
doi = {10.1111/ina.13099},
number = {8},
pages = {e13099},
volume = {32},
abstract = {Abstract Particle size removal efficiencies for 0.1Ð1.0Ê?m (PSE0.1?1.0\$\$ {PSE}\_{0.1-1.0} \$\$) and 0.3Ð1.0Ê?m (PSE0.3?1.0\$\$ {PSE}\_{0.3-1.0} \$\$) diameter of Minimum Efficiency Reporting Value (MERV) filters, an electrostatic enhanced air filter (EEAF), and their two-stage filtration systems were evaluated. Considering the most penetrating particle size was 0.1Ð0.4Ê?m particulate matter (PM), the PSE0.1?1.0\$\$ {PSE}\_{0.1-1.0} \$\$ as an evaluation parameter deserves more attention during the COVID-19 pandemic, compared to the PSE0.3?1.0\$\$ {PSE}\_{0.3-1.0} \$\$. The MERV 13 filters were recommended for a single-stage filtration system because of their superior quality factor (QF) compared to MERV 6, MERV 8, MERV 11 filters, and the EEAF. Combined MERV 8?+?MERV 11 filters have the highest QF compared to MERV 6?+?MERV 11 filters and EEAF?+?MERV 11 filters; regarding 50\% of PSE0.1?1.0\$\$ {PSE}\_{0.1-1.0} \$\$ as the filtration requirements of two-stage filtration systems, the MERV 8?+?MERV 11 filtration system can achieve this value at 1.0Êm/s air velocity, while PSE0.1?1.0\$\$ {PSE}\_{0.1-1.0} \$\$ values were lower than 50\% at 1.5Êm/s and 2.0Êm/s. EEAF obtained a better PSE0.3?1.0\$\$ {PSE}\_{0.3-1.0} \$\$ in the full-recirculated test rig than in the single-pass mode owing to active ionization effects when EEAF was charged by alternating current.},
journal = {Indoor Air},
keywords = {electrostatic filters, filtration performances, HVAC, minimum efficiency reporting value, particulate matter, recirculation},
year = {2022}
}
@article{ZAMANI2022686,
author = {M. Zamani and E. Abbasi-Atibeh and J.S. Olfert and L.W. Kostiuk},
title = {Co-flow jet diffusion flames in a multi-slot burner: Flow field and emissions},
doi = {10.1016/j.psep.2022.08.069},
pages = {686-694},
volume = {167},
abstract = {Motivated by the application of internally air-assisted flares and recent anomalous data that black carbon (BC) emissions changes are not monotonic with the amount of air added inside the fuel stream, a burner was designed to study the flow, emissions, and stability aspects of the existence of both normal and inverse jet diffusion flames in close proximity. Since the radius of curvature of a burner affects all aspects of combustion, such as dynamics, stability, flame structure, and emissions, a slot burner configuration, inspired by the Wolfhard-Parker burner, was adopted. This multi-slot burner consists of five parallel rectangular slots (i.e., the central slot for the inner air, sandwiched between two fuel slots, and surrounded by two outer air slots). When operated with laminar fuel and air flows, this burner produced flame sheets at each fuel-air mixing layer with open optical access to all the flows. Flow fields were characterized using two-dimensional two-component particle image velocimetry, while simultaneous single-lens reflex photography was used to establish the overall height and the location of the flames. Emission measurements specifically targeted BC, a precursor of soot, and oxides of nitrogen (NOx). The experimental test conditions involved constant flows of outer air and propane, and variable inner air flow. At one extreme, i.e., zero inner air flow, two flame bases were produced at the interfaces between the fuel and outer air streams. These flames merged to produce a normal diffusion flame. With the addition of inner air, two more flame bases appeared (referred to as the inner flame) and formed an inverse diffusion flame. With increasing inner air flow, the inner flame transitioned from a closed-tip flame, to an open-tip flame, and eventually to a lifted flame. With increasing inner air flow, the NOx emissions remained constant while the BC emissions, which were 3 g/kg-fuel with no inner air, rose by an order of magnitude as it became an open-tip flame. Only when the inner flame finally lifted off due to the inner air flow, did the BC emissions collapse to near zero. Phenomenological models associated with the importance of partial premixing were proposed to explain this collapse, thereby generalizing this finding to other combustion systems when attempting to reduce BC emissions through secondary internal air addition.},
journal = {Process Safety and Environmental Protection},
keywords = {Normal and inverse jet diffusion flame, Multi-slot burner, Particle image velocimetry, Emission index, Black carbon, Lift-off},
year = {2022}
}
@article{Bello2023,
author = {Olanrewaju W. Bello and Ehsan Abbasi-Atibeh and Larry Kostiuk and Jason S. Olfert},
title = {Effects of external injection of deionized water and water with impurities on Water-assisted flares},
doi = {10.1016/j.fuel.2023.127602},
pages = {127602},
volume = {340},
abstract = {Water-assisted flares are used on offshore platforms and occasionally at downstream oil and gas facilities to reduce soot and oxides of nitrogen (NOx) emissions and flame luminosity. Typically, water-assisted flares inject water into the flame from outside the flare stack (external injection), and the water often contains high concentrations of impurities. Different configurations of water injection were explored using a range of water flow rates, atomizer angles, and radial displacements from the burner center to understand the effects of water flow rate and location of water entrainment into the flame on emissions. A range of sodium chloride (NaCl) concentrations was also tested as a surrogate species for the impurities contained in the water used at offshore and downstream oil and gas facilities. Flow visualization analysis was carried out, and the water droplet velocity field was used to discuss their motion transitioning from being dominated by their momentum to that of the buoyancy of the combustion products. This study used atmospheric turbulent non-premixed flames on a two-inch circular burner at a constant propane flow rate of 20 standard L/min. It was discovered that the atomizerÕs angular displacement plays a significant role in black carbon (BC) and NOxemissions suppression, but the atomizerÕs horizontal displacement does not affect NOx emission. Water directed very close to the base of the flame ensured water was present early in the combustion process relative to other external injected configurations and reduced emissions by a greater extent compared to when the water was directed higher in the flame. The buoyancy of the flame affects the velocity of the injected water, helps to redirect its flow in the flame, and increases its mixing with fuel and air. Large amounts of water droplets pass through the flame front and evaporate within the fuel side of the flame envelope. The flame color and luminosity were affected by an increased NaCl concentration and the different configurations of the injected water. Higher NaCl concentration in the water causes an increase in BC emissions and a slight decrease in NOx emissions relative to deionized water. The smaller NaCl concentration in the water does not affect NOxand BC emissions compared to deionized water.},
journal = {Fuel},
keywords = {Emissions suppression, Water Assist and Salt Solution, Turbulent Non-premixed Flame, Flare, Emission Indices, Particle Image Velocimetry},
year = {2023}
}
@article{Senaratne2023,
author = {Amrith Senaratne and Jason Olfert and Greg Smallwood and Fengshan Liu and Prem Lobo and Joel C. Corbin},
title = {Size and light absorption of miniature-inverted-soot-generator particles during operation with various fuel mixtures},
doi = {10.1016/j.jaerosci.2023.106144},
pages = {106144},
volume = {170},
abstract = {The Argonaut miniature inverted soot generator (MISG) serves as a convenient and stable source of soot black-carbon aerosol particles. The MISG performance has been previously characterized for ethylene and propane, in a simple two-flow setup of fuel and air. These fuels produce soot size distributions with geometric median diameters (GMDs) of 150Ð200Ênm. These sizes are substantially larger than the soot particles emitted from typical internal-combustion and aviation gas turbine engines. Here, we sought to produce substantially smaller soot particles, representative of aviation gas turbine engine emissions, by using five different fuels (acetylene, methane, ethylene, propane, and dimethyl ether) and by enriching the combustion air with oxygen. We developed a rapid screening protocol for each fuel, to allow the full range of stable flame conditions to be explored. We monitored the size distribution, mass concentration, and mass absorption cross section (MAC) of denuded MISG soot in real time. We considered only operating conditions where stable soot mass concentrations above 3Êug/m3 were emitted, corresponding to a non-flickering and open-tipped flame. For virtually all operating conditions, the measured MAC was consistent with literature values for mature soot. The only exception was a propane-acetylene mixture, for which the measured MAC was much lower than literature values. The observed GMDs fell into two groups, and we did not identify any trends leading to the mixtures falling into either group. The two groups were at approximately 100Ênm and 160Ênm. Therefore, while this study identified conditions that reduced the soot particles to 100Ênm, it did not identify conditions where even smaller soot particles could be produced. This study has demonstrated that the soot properties produced by the MISG are highly repeatable and relatively insensitive to fuel composition.},
journal = {Journal of Aerosol Science},
keywords = {Soot, Generator, Calibration, Flame, Inverted, Argonaut},
year = {2023}
}
@article{Tatum2023,
author = {James Tatum and Ambuj Punia and Larry Kostiuk and Marc Secanell and Jason Olfert},
title = {Dataset of methane pyrolysis products in a batch reactor as a function of time at high temperatures and pressures},
doi = {10.1016/j.dib.2023.108953},
pages = {108953},
volume = {47},
abstract = {Methane pyrolysis is a process used to generate hydrogen gas and carbon black without the creation of carbon dioxide. Methane pyrolysis in a constant volume batch reactor was investigated at temperatures of 892, 1093, and 1292ÊK with reaction times of 15, 30, 60, 180, and 300Ês at an initial pressure of 399ÊkPa. A quartz vessel (32ÊmL) was placed inside an oven where it was heated to high temperatures. At the beginning of the process, the quartz vessel was vacuumed, then flushed with nitrogen before being vacuumed again prior to every experiment. Pressurized methane was then injected into the vessel for an allocated reaction time and collected in a sample bag post reaction for analysis. The molar concentration of the product gas was analyzed using gas chromatography. Hydrogen molar concentration increased as temperature and reaction time increased. For experiments completed at 892ÊK the hydrogen molar concentration varied from 10.0ʱÊ5.9% with a 15Ês reaction time to 26.5ʱÊ0.8% for a 300Ês reaction time. For experiments completed at 1093 K the hydrogen molar concentration varied from 21.8ʱÊ3.7% for a 15Ês reaction time to 53.0ʱÊ2.9% for a 300Ês reaction time. For experiments completed at 1292ÊK the hydrogen molar concentration varied from 31.5ʱÊ1.7% for a 15Ês reaction time to 53.0ʱÊ2.4% for a 300Ês reaction time.},
journal = {Data in Brief},
keywords = {Methane decomposition, Hydrogen production, Constant-volume reactor, Green technology, CO free},
year = {2023}
}
@article{Perraud2023,
author = {V{\'{e}}ronique Perraud and James N. Smith and Jason Olfert},
title = {High-accuracy effective density measurements of sodium methanesulfonate and aminium chloride nanoparticles using a particulate calibration standard},
doi = {10.1080/02786826.2023.2176739},
number = {4},
pages = {355-366},
volume = {57},
abstract = {AbstractMethanesulfonate and aminium salts are commonly found in ambient nanoparticles and are often used as calibration standards. However, the effective densities of the particles generated from these standards are required if they are to be used to calibrate aerosol mass spectrometers or to estimate hygroscopic growth factors from electrodynamic balance experiments. A centrifugal particle mass analyzer and scanning mobility particle sizer were used in tandem (CPMA-SMPS) to measure the effective density of five salts. The effective densities were determined to be: sodium methanesulfonate, 1474? +/- ?13?kg m^3; methylammonium chloride, 1236+/- ?29 kg m^3, monoethanolamine hydrochloride, 1136?+/- ?26kg m^3; 1,4-diaminobutane dihydrochloride, 1135?+/- ?33?kg m^3; and NaCl was found to have a size-dependent effective density due to its non-spherical shape. It is also shown how Santovac vacuum pump oil can be used to accurately calibrate the CPMA-SMPS system for particles less than 100?nm in diameter, which is a size range that has been problematic for calibration techniques relying on polystyrene latex spheres.},
journal = {Aerosol Science and Technology},
publisher = {Taylor & Francis},
year = {2023}
}
@article{Punia2023,
author = {A. Punia and J. Tatum and L. Kostiuk and J. Olfert and M. Secanell},
title = {Analysis of methane pyrolysis experiments at high pressure using available reactor models},
doi = {10.1016/j.cej.2023.144183},
pages = {144183},
volume = {471},
abstract = {Most batch reactor methane thermal decomposition (MTD) studies have focused on sub-atmospheric pressures. In this study, MTD experiments were performed between 892 K and 1292 K and 4 atm inside a quasi-isothermal quartz batch reactor at residence times ranging from 0 to 300 s. At a given temperature, elevated pressure resulted in higher methane conversion compared with the sub-atmospheric conditions. A zero-dimensional, closed, isochoric, homogeneous gas-phase model was used to compare numerical predictions from available reaction mechanisms in literature to experimental data. It was found that most models accurately predict conversion at low pressure and high temperature and at high pressure and high temperature, but did not accurately predict methane, hydrogen, and intermediate species mole fractions at 4 atm and either 892 K or 1093 K. A reaction path analysis showed the reactions responsible for the delay in hydrogen formation at elevated pressure are 2CH3 (+M) ? C2H6, C2H6 ? CH3 ? C2H5 ? CH4, C2H6 ? H ? C2H5 ? H2 and C2H5 (+M) ? C2H4 ? H, where M is the collision partner. A gas-phase model accounting for the solid carbon shows that the observed discrepancy is not due to the unavailability of the carbon formation model but to slower reaction kinetics, especially at lower temperatures. The experimental data presented can be used to obtain a methane pyrolysis reaction mechanism suitable for high pressure conditions.},
journal = {Chemical Engineering Journal},
keywords = {Methane pyrolysis, Batch reactor, Reaction kinetic modeling, Experiments, Hydrogen},
year = {2023}
}
@article{Naseri2023,
author = {A. Naseri and T. J. Johnson and G. Smallwood and J. S. Olfert},
title = {Measurement of the centrifugal particle mass analyzer transfer function},
doi = {10.1080/02786826.2023.2228378},
number = {10},
pages = {963--980},
volume = {57},
abstract = {Particle mass analyzers, in particular the centrifugal particle mass analyzer (CPMA) and the aerosol particle mass analyzer (APM), have provided new possibilities for aerosol science through their ability to classify particles by their mass-to-charge ratio. The performance of the CPMA in classifying particles is characterized by a probability distribution known as a transfer function. This study shows the theoretical models of the CPMAÕs transfer function that exist in the literature cannot accurately predict the CPMAÕs actual performance. In this study, a tandem CPMA (TCPMA) measurement technique was used to experimentally evaluate the deviation of the actual CPMA transfer function from its idealized triangular transfer function. This deviation was measured by three factors: (i) the width factor (?), (ii) the height factor (?), and (iii) the mass set point agreement (i.e., the agreement between the set points of the two CPMAs, m12?); such that concurrent values of 1 for all three factors implied no deviation between the actual and theoretical triangular CPMA transfer functions. These factors were derived by adjusting them to fit TCPMA data with the convolution of two triangular transfer functions with identical widths. TCPMA data were collected for a wide range of CPMA resolutions, flow rates, and mass set points ranging from 2 to 15, 0.3 to 8 LPM, and 0.05 to 100 fg, respectively. The mass set point agreement remained relatively constant over a range of CPMA mass set points and increased slightly with decreasing CPMA resolutions. Neglecting outliers, the average mass set point agreement was m12?=1.02±0.03, suggesting good reproducibility among the CPMAs. The width factor showed a functional dependence on the mass set point, resolution, and flow rate. It was observed that the CPMA transfer function was generally narrower (?>1) than the idealized transfer function except at a low flow rate (0.3 LPM) and low mass set points (m?<1 fg), and the width factor approached unity at higher mass set points (m?>1 fg) and higher resolutions (Rm>6). As expected, the height factor depends on the mass set point, resolution, and flow rate: it decreases with lower mass set points, lower flow rates and higher resolutions. Both the width and height factors were fitted robustly using multivariate non-linear fitting models so that CPMA users can easily calculate its transfer function over a wide range of operating conditions.},
journal = {Aerosol Science and Technology},
year = {2023}
}
@article{Sipkens2023a,
author = {Timothy A. Sipkens and Adam Boies and Joel C. Corbin and Rajan K. Chakrabarty and Jason Olfert and Steven N. Rogak},
title = {Overview of methods to characterize the mass, size, and morphology of soot},
doi = {10.1016/j.jaerosci.2023.106211},
pages = {106211},
volume = {173},
journal = {Journal of Aerosol Science},
year = {2023}
}
@article{Zhang2023,
author = {Zhang, Boxin and Aravind, Indu and Yang, Sisi and Weng, Sizhe and Zhao, Bofan and Johnson, Grace and Brown, Lucas and Olfert, Jason and Jung, Heejung and Cronin, Stephen B.},
title = {Ion density-enhanced electrostatic precipitation using high voltage nanosecond pulses},
doi = {10.1039/D3VA00148B},
number = {11},
pages = {1566--1573},
volume = {2},
abstract = {his study evaluates the beneficial effects of discharging nanosecond pulse transient plasma (NPTP) in a coaxial electrostatic precipitator for capturing nanoscale soot particles (?50 nm) produced by an ethylene flame. Here{,} the nanoscale soot particles are collected using two different reactor geometries: a 3'' diameter reactor with a mean flow velocity of 1.2 m s?1 and a 1.5?? diameter reactor with a mean flow velocity 1.5 m s?1{,} corresponding to volumetric flow rates of 11.5 CFM and 3.6 CFM{,} respectively. The nanosecond high voltage pulses (+20 kV{,} 20 ns{,} 800 Hz) are applied in conjunction with DC bias voltages. While nearly 100% collection efficiency can be achieved without NPTP at sufficiently high DC voltages (|VDC| > 14 kV){,} this drops below 50% for lower DC voltages (|VDC| < 10 kV). With NPTP{,} we observe substantially enhanced remediation (up to 23?) at lower DC voltages (|VDC| < 10 kV) due to the enhanced ion density produced by the plasma. For DC-only electrostatic precipitation{,} the charging of soot particles takes place via a DC corona{,} whose ion density is several orders of magnitude lower than that of the NPTP{,} which produces a streamer discharge due to the fast rise times of the nanosecond pulses (i.e.{,} dV/dt ? 1012 V s?1). High speed imaging of the plasma emission profile indicates that ion densities 106 times higher are achieved with the nanosecond pulsed plasma{,} as compared to that of the DC corona. At lower DC voltages (i.e.{,} |VDC| < 10 kV){,} the charging of soot particles is a key factor limiting the DC-only remediation efficiencies{,} and NPTP provides a way to mitigate this limitation.},
journal = {Environmental Science: Advances},
year = {2023}
}
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