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Title: Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines

Authors:
;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1389698
Grant/Contract Number:
FC02-07ER64494
Resource Type:
Journal Article: Published Article
Journal Name:
Fuel
Additional Journal Information:
Journal Volume: 196; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-09-12 19:02:02; Journal ID: ISSN 0016-2361
Publisher:
Elsevier
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Sakai, Stephen, and Rothamer, David. Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines. United Kingdom: N. p., 2017. Web. doi:10.1016/j.fuel.2017.01.070.
Sakai, Stephen, & Rothamer, David. Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines. United Kingdom. doi:10.1016/j.fuel.2017.01.070.
Sakai, Stephen, and Rothamer, David. Mon . "Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines". United Kingdom. doi:10.1016/j.fuel.2017.01.070.
@article{osti_1389698,
title = {Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines},
author = {Sakai, Stephen and Rothamer, David},
abstractNote = {},
doi = {10.1016/j.fuel.2017.01.070},
journal = {Fuel},
number = C,
volume = 196,
place = {United Kingdom},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.fuel.2017.01.070

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  • A combined experimental and modeling effort was performed in order to understand how particulate matter (PM) is formed in spark-ignition (SI) internal combustion engines. Parameters that affect global and local air/fuel ratios strongly affect PM. Minimum PM number and mass concentrations are emitted at a global air/fuel ratio within 10% of stoichiometric, and concentrations increase by as many as 3 orders of magnitude when the air/fuel ratio is either increased or decreased 30% from stoichiometric. Burning liquid fuel is a significant source of PM, as evidenced by the fact that open valve fuel injection increases PM concentrations by up tomore » 3 orders of magnitude relative to closed valve injection. Coolant and oil temperatures, spark timing, and exhaust gas recirculation (EGR) affect PM through their effect on intake port and cylinder temperatures as well as through the effect on the availability of liquid fuel in the cylinder. Particle sizes as a function of engine operating conditions are discussed.« less
  • A combined experimental and modeling effort was performed in order to understand how particulate matter (PM) is formed in spark-ignition (SI) internal combustion engines. Fuel type and fuel/air ratio strongly affect particle concentrations. PM emissions vary by up to 6 orders of magnitude between fuels at the same fuel/air ratio. Minimum PM concentrations are emitted at a global fuel/air ratio within 10% of stoichiometric, with the exact value depending on the particular fuel. Concentrations can increase by more than 3 orders of magnitude when the fuel/air ratio is either increased or decreased 30% from stoichiometric. Particles derived from oil consumptionmore » were found to be between 0 and 40% of the PM concentration for the oils used in the present experiments. Differences in PM emissions with and without the catalytic converter are not statistically significant. Particulate number and mass concentrations plus particle sizes are addressed in this paper, as is the correlation between PM and hydrocarbon (HC) emissions.« less
  • Recent health concerns over airborne particulate matter (PM) have prompted examination of the mechanisms by which PM is formed in spark ignition (SI) internal combustion engines. A study was undertaken in order to understand the effects of dilution on measured PM, to examine and model the effect of steady state engine operating conditions on engine-out PM, and to characterize the effect of transient engine conditions on particle growth and dynamics. Particle dynamics in diluted SI and compression ignition (CI) engine exhaust are examined and discussed in the context of SI exhaust dilution. Temperature measurements in the exhaust pipe and dilutionmore » tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52 C. Measurements of PM concentrations as a function of dilution ratio, using a Scanning Mobility Particle Sizer (SMPS), show the competing effects of temperature and particle/vapor concentrations on particle growth dynamics, which result in a range of dilution ratios--from 13 to 18--where the effect of dilution ratio, independent of flowrate, is kept to a minimum and is therefore optimal in order to achieve repeatable PM concentration measurements. Particle dynamics in transit through the dilution tunnel are measured and compared to previous research. PM emissions are strongly affected by steady state engine parameters that affect global and local air/fuel ratios, the concentration of liquid fuel in the cylinder, and the availability of soot precursors. PM emissions vary by up to six orders of magnitude between the fuels tested, when at the same fuel/air equivalence ratio. Minimum PM concentrations are emitted at a global fuel/air ratio within 10% of stoichiometric, with the exact value depending on the particular fuel, and concentrations can increase by more than three orders of magnitude when the fuel/air ratio is either increased or decreased 30% from stoichiometric. Burning liquid fuel is a significant source of PM, as evidenced by the fact that open valve fuel injection increases PM emissions by up to three orders of magnitude relative to closed valve injection. Coolant and oil temperatures, spark timing, and Exhaust Gas Recirculation (EGR) affect PM through their effect on intake port and cylinder temperatures, as well as through the effect on the availability of liquid fuel in the cylinder. Particles derived from oil consumption were found to be between zero and 40% of the total PM concentration for the oils used in the present experiments. Differences in PM emissions with and without the catalytic converter are not statistically significant. Particulate number and mass concentrations plus particle sizes are addressed in the present paper, as is the correlation between PM and emissions of gaseous pollutants--hydrocarbons (HCs), oxides of nitrogen (NOx), oxides of carbon (CO and CO{sub 2})--as well as oxygen and characteristic temperatures and pressures during the engine cycle. A model of PM formation via homogeneous- and heterogeneous-phase reactions, growth via condensation and adsorption/absorption of vapors, and diminution via oxidation explains the observed behavior of PM emissions with respect to each of the engine, fuel, and dilution parameters above. PM emissions during transient engine operation are generally a first-order time response with characteristic times similar to those involved in the fuel evaporation process, suggesting that PM emissions respond to instantaneous engine conditions and may be modeled using a quasi-steady state application of the model.« less
  • A relationship has been observed between increasing ethanol content in gasoline and increased particulate matter (PM) emissions from direct injection spark ignition (DISI) vehicles. The fundamental cause of this observation is not well understood. One potential explanation is that increased evaporative cooling as a result of ethanol's high HOV may slow evaporation and prevent sufficient reactant mixing resulting in the combustion of localized fuel rich regions within the cylinder. In addition, it is well known that ethanol when blended in gasoline forms positive azeotropes which can alter the liquid/vapor composition during the vaporization process. In fact, it was shown recentlymore » through a numerical study that these interactions can retain the aromatic species within the liquid phase impeding the in-cylinder mixing of these compounds, which would accentuate PM formation upon combustion. To better understand the role of the azeotrope interactions on the vapor/liquid composition evolution of the fuel, distillations were performed using the Advanced Distillation Curve apparatus on carefully selected samples consisting of gasoline blended with ethanol and heavy aromatic and oxygenated compounds with varying vapor pressures, including cumene, p-cymene, 4-tertbutyl toluene, anisole, and 4-methyl anisole. Samples collected during the distillation indicate an enrichment of the heavy aromatic or oxygenated additive with an increase in initial ethanol concentration from E0 to E30. A recently developed distillation and droplet evaporation model is used to explore the influence of dilution effects versus azeotrope interactions on the aromatic species enrichment. The results suggest that HOV-cooling effects as well as aromatic species enrichment behaviors should be considered in future development of predictive indices to forecast the PM potential of fuels containing oxygenated compounds with comparatively high HOV.« less
  • The purpose of the report is to provide simple explanations regarding the formation and control of combustion pollutants from gasoline-fueled spark-ignition motor vehicle engines. Formation phenomena are explained on the basis of well-known cause and effect relationships. Pollution control techniques are explained on the basis of the operating characteristics of systems which are already in widespread use. Two appendices are included which present additional information.