Characterization of Particulate Matter Morphology and Volatility from a Compression-Ignition Natural-Gas Direct-Injection Engine

Graves, Brian; Olfert, Jason S.; Patychuk, Bronson; Dastanpour, Ramin; Rogak, Steven N.

doi:10.1080/02786826.2015.1050482

Cited by 51 publications

(32 citation statements)

References 39 publications

(57 reference statements)

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“…The figure shows there is relatively more condensed material at smaller particle sizes. This is consistent with observations on particles emitted from a diesel engine (Sakurai et al 2003;Ristimaki et al 2007), a compression-ignition natural-gas direct-injection engine (Graves et al 2015), and a premixed ethylene flame (Ghazi et al 2013). …”

Section: Volatility Of the Particle Emissionssupporting

confidence: 80%

Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement

Momenimovahed

Olfert

2015

Aerosol Science and Technology

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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 4278d m ¡0.438 § 76.3 kg/m 3 (for mobility diameter, d m , in nm) for nascent particles and 3215d m ¡0.395 § 37.9 kg/m 3 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.

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Section: Volatility Of the Particle Emissionssupporting

confidence: 80%

Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement

Momenimovahed

Olfert

2015

Aerosol Science and Technology

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“…Based on the upstream CPC measurements, the total semi-volatile fraction in terms of particle number was found to be <20% from either smoke source, indicating that most particles are heterogeneous containing both semi-volatile and nonvolatile components. Particles with high mass volatility can also be produced from combustion engines 43 although this is typically accompanied by higher number-based semi-volatile fractions than are observed here. Furthermore, purely semi-volatile particles may manifest as another distinct peak in a particle size or mass distribution 44 , however, all size and mass distributions measured were uni-modal.…”

Section: Resultsmentioning

confidence: 68%

Comprehensive characterization of mainstream marijuana and tobacco smoke

Graves

Johnson

Nishida

et al. 2020

Sci Rep

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Recent increases in marijuana use and legalization without adequate knowledge of the risks necessitate the characterization of the billions of nanoparticles contained in each puff of smoke. Tobacco smoke offers a benchmark given that it has been extensively studied. Tobacco and marijuana smoke particles are quantitatively similar in volatility, shape, density and number concentration, albeit with differences in size, total mass and chemical composition. Particles from marijuana smoke are on average 29% larger in mobility diameter than particles from tobacco smoke and contain 3.4× more total mass. New measurements of semi-volatile fractions determine over 97% of the mass and volume of the particles from either smoke source are comprised of semi-volatile compounds. For tobacco and marijuana smoke, respectively, 4350 and 2575 different compounds are detected, of which, 670 and 536 (231 in common) are tentatively identified, and of these, 173 and 110 different compounds (69 in common) are known to cause negative health effects through carcinogenic, mutagenic, teratogenic, or other toxic mechanisms. This study demonstrates striking similarities between marijuana and tobacco smoke in terms of their physical and chemical properties.

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“…For HPDI tests, higher TD temperatures were also tested and no significant change was observed in particle number and size distributions. Although this is not a precise way to determine the mass of organics on the soot, but a change in the size distribution (Graves et al 2015) will be observed for semi-volatile mass fractions of 10% or more. Even if 10% of the particle mass was composed of volatile material, primary particle diameter would have approximately decreased by only 5% under the vacuum condition of the TEM (considering densities of the particle core and coating to be 1800 kg=m 3 and 1200 kg=m 3 , respectively).…”

Section: Methodsmentioning

confidence: 99%

“…Details of the experimental methods are further described in Dastanpour and Rogak (2014) and Graves et al (2015).…”

Section: Methodsmentioning

confidence: 99%

Improved sizing of soot primary particles using mass-mobility measurements

Dastanpour

Rogak

Graves

et al. 2015

Aerosol Science and Technology

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The 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 k a and exponent D a ). 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 k a and D a that can be used for all conditions. However, new optimized values of k a and D a 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 k a and D a , 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.

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Characterization of Particulate Matter Morphology and Volatility from a Compression-Ignition Natural-Gas Direct-Injection Engine

Cited by 51 publications

References 39 publications

Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement

Effective Density and Volatility of Particles Emitted from Gasoline Direct Injection Vehicles and Implications for Particle Mass Measurement

Comprehensive characterization of mainstream marijuana and tobacco smoke

Improved sizing of soot primary particles using mass-mobility measurements

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