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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. 2017. "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 = 2017,
month = 5
}

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
  • 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.
  • Gasoline compression ignition concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multi-cylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies has been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection strategy to createmore » a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from -91° to -324° ATDC, which is just after the exhaust valve closes for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 L diesel engine with a variable geometry turbocharger, high pressure common rail injection system, wide included angle injectors, and variable swirl actuation was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection GTP-15-1067, Dempsey 2 pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).« less