The Effect of Fuel and Engine Design on Diesel Exhaust Particle Size Distributions

Baumgard, Kirby J.; Johnson, John H.

doi:10.4271/960131

Cited by 123 publications

(75 citation statements)

References 14 publications

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“…Several studies indicated that exhaust secondary particle formation is related to high FSC and exhaust aftertreatment such as the use of oxidation catalysts. 9,10,40 Measurements of gaseous H 2 SO 4 are extremely difficult to perform. 41 So far, exhaust gaseous H 2 SO 4 measurements have been carried out only by Arnold et al, 42 indicating maximum SO 2 -to-SO 3 conversion of up to 90%.…”

Section: Resultsmentioning

confidence: 99%

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

Uhrner

Zallinger

Löwis

et al. 2011

Journal of the Air & Waste Management Association

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A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.

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Section: Resultsmentioning

confidence: 99%

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

Uhrner

Zallinger

Löwis

et al. 2011

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

show abstract

“…From an engineering standpoint, changes in engine design, or fuel composition, may affect not only particle mass emissions, but their size and composition as well. As one example, a modern heavy duty diesel engine has been cited to give lower PM mass emissions, yet with particle numbers equal to or exceeding those from an older technology engine (Baumgard and Johnson 1996). In another study, dimethoxy methane additive to diesel fuel was found to reduce PM mass in 1 National Ambient Air Quality Standard for Particulate Matter: Final Rule, Federal Register, 1997, 62, 38652. the exhaust by reducing particle size, but not their number (Maricq et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Size Distributions of Motor Vehicle Exhaust PM: A Comparison Between ELPI and SMPS Measurements

Maricq¹,

Podsiadlik²,

Chase³

2000

Aerosol Science and Technology

178

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ABSTRACT. Particle size measurements using the electrical low pressure impactor (ELPI) and scanning mobility particle sizer (SMPS) are compared from the perspective of characterizing the particulate matter in motor vehicle exhaust. Both steady state vehicle operation and transient drive cycles are considered, and both gasoline and diesel fueled vehicle emissions are compared. Although the ELPI and SMPS measure different physical properties, respectively, the aerodynamic diameter and mobility diameter, the steady state particle size distributions are in close agreement, except for the 37 nm impactor stage of the ELPI which may overestimate particle number by up to a factor of two relative to the SMPS. This has little effect on the volume, or mass, weighted distribution. These, too, are generally in good agreement, though discrepancies appear at large particle size due to multiple charging effects in the SMPS and to electrometer offsets and the small particle loss correction in the ELPI. Selecting particles based on their electrical mobility with the SMPS, and then measuring their aerodynamic diameter with the ELPI, reveals that diesel particulate matter with well-speci ed mobility diameter exhibits a wide range in aerodynamic diameter and, therefore, also in effective density. Over transient drive cycles, the ELPI provides second by second particle distributions, whereas the SMPS must be run in a xed particle size mode and size distributions constructed from repeated tests. The ELPI registers higher instantaneous PM emission rates during transients than the SMPS due to the faster time responses of the ELPI. The time integrated ELPI and SMPS size distributions, however, remain in good agreement. The relative merits of the two instruments for steady state and transient tests are discussed.

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“…The precise composition of the nucleation mode is not fully known. Baumgard and Johnson, 22 Shi and Harrison, 23 Khalek et al, 18 and Kim et al 24,25 have suggested that the formation of nucleation-mode particles is due to the nucleation of sulfuric acid and water, resulting in the formation of approximately 1-nm-sized semi-volatile particles. Nucleated particles grow by condensation and sorption of HC species.…”

Section: Introductionmentioning

confidence: 99%

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

Swanson

Kittelson

Pui

et al. 2010

Journal of the Air & Waste Management Association

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This paper is part of the Journal of the Air & Waste Management Association's 2010 special issue on combustion aerosol measurements. The issue is a combination of papers that synthesize and evaluate ideas and perspectives that were presented by experts at a series of workshops sponsored by the Coordinating Research Council that aimed to evaluate the current and future status of diesel particulate matter (DPM) measurement. Measurement of DPM is a complex issue with many stakeholders, including air quality management and enforcement agencies, engine manufacturers, health experts, and climatologists. Adoption of the U.S. Environmental Protection Agency 2007 heavy-duty engine DPM standards posed a unique challenge to engine manufacturers. The new standards reduced DPM emissions to the point that improvements to the gravimetric method were required to increase the accuracy and the sensitivity of the measurement. Despite these improvements, the method still has shortcomings. The objectives of this paper are to review the physical and chemical properties of DPM that make gravimetric measurement difficult at very low concentrations and to review alternative metrics and methods that are potentially more accurate, sensitive, and specific. Particle volatility, size, surface area, and number metrics are considered, as well as methods to quantify them. Although the authors believe that an alternative method is required to meet the needs of engine manufacturers, the methods reviewed in the paper are applicable to other areas where the gravimetric method detection limit is approached and greater accuracy and sensitivity are required. The paper concludes by suggesting a method to measure active surface area, combined with a method to separate semi-volatile and solid fractions to further increase the specificity of the measurement, has potential for reducing the lower detection limit of DPM and enabling engine manufacturers to reduce DPM emissions in the future.

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The Effect of Fuel and Engine Design on Diesel Exhaust Particle Size Distributions

Cited by 123 publications

References 14 publications

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust

Size Distributions of Motor Vehicle Exhaust PM: A Comparison Between ELPI and SMPS Measurements

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

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