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Title: Modeling and cold start in alcohol-fueled engines

Abstract

Neat alcohol fuels offer several benefits over conventional gasoline in automotive applications. However, their low vapor pressure and high heat of vaporization make it difficult to produce a flammable vapor composition from a neat alcohol fuel during a start under cold ambient conditions. Various methods have been introduced to compensate for this deficiency. In this study, the authors applied computer modeling and simulation to evaluate the potential of four cold-start technologies for engines fueled by near-neat alcohol. The four technologies were a rich combustor device, a partial oxidation reactor, a catalytic reformer, and an enhanced ignition system. The authors ranked the competing technologies by their ability to meet two primary criteria for cold starting an engine at {minus}25 deg C and also by several secondary parameters related to commercialization. Their analysis results suggest that of the four technologies evaluated, the enhanced ignition system is the best option for further development.

Authors:
;
Publication Date:
Research Org.:
National Renewable Energy Lab., Golden, CO (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
OSTI Identifier:
650264
Report Number(s):
NREL/TP-540-24180
ON: DE98005250; TRN: AHC2DT04%%177
DOE Contract Number:
AC36-83CH10093
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: May 1998
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; 09 BIOMASS FUELS; ALCOHOL FUELS; AUTOMOTIVE FUELS; FUEL SUBSTITUTION; COMBUSTION KINETICS; START-UP; IGNITION SYSTEMS; COMMERCIALIZATION

Citation Formats

Markel, A.J., and Bailey, B.K. Modeling and cold start in alcohol-fueled engines. United States: N. p., 1998. Web. doi:10.2172/650264.
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Markel, A.J., & Bailey, B.K. Modeling and cold start in alcohol-fueled engines. United States. doi:10.2172/650264.
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Markel, A.J., and Bailey, B.K. Fri . "Modeling and cold start in alcohol-fueled engines". United States. doi:10.2172/650264. https://www.osti.gov/servlets/purl/650264.
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@article{osti_650264,
title = {Modeling and cold start in alcohol-fueled engines},
author = {Markel, A.J. and Bailey, B.K.},
abstractNote = {Neat alcohol fuels offer several benefits over conventional gasoline in automotive applications. However, their low vapor pressure and high heat of vaporization make it difficult to produce a flammable vapor composition from a neat alcohol fuel during a start under cold ambient conditions. Various methods have been introduced to compensate for this deficiency. In this study, the authors applied computer modeling and simulation to evaluate the potential of four cold-start technologies for engines fueled by near-neat alcohol. The four technologies were a rich combustor device, a partial oxidation reactor, a catalytic reformer, and an enhanced ignition system. The authors ranked the competing technologies by their ability to meet two primary criteria for cold starting an engine at {minus}25 deg C and also by several secondary parameters related to commercialization. Their analysis results suggest that of the four technologies evaluated, the enhanced ignition system is the best option for further development.},
doi = {10.2172/650264},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri May 01 00:00:00 EDT 1998},
month = {Fri May 01 00:00:00 EDT 1998}
}
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Technical Report:
View Technical Report (4.70 MB)
DOI:  10.2172/650264
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  • ;
    The authors have completed a study in which they investigated the use of a rich combustor to aid in cold starting spark-ignition engines fueled with either neat ethanol or neat methanol. The rich combustor burns the alcohol fuel outside the engine under fuel-rich conditions to produce a combustible product stream that is fed to the engine for cold starting. The rich combustor approach significantly extends the cold starting capability of alcohol-fueled engines. A design tool was developed that simulates the operation of the combustor and couples it to an engine/vehicle model. This tool allows the user to determine the fuelmore » requirements of the rich combustor as the vehicle executes a given driving mission. The design tool was used to design and fabricate a rich combustor for use on a 2.8 L automotive engine. The system was tested using a unique cold room that allows the engine to be coupled to an electric dynamometer. The engine was fitted with an aftermarket engine control system that permitted the fuel flow to the rich combustor to be programmed as a function of engine speed and intake manifold pressure. Testing indicated that reliable cold starts were achieved on both neat methanol and neat ethanol at temperatures as low as {minus}20 C. Although starts were experienced at temperatures as low as {minus}30 C, these were erratic. They believe that an important factor at the very low temperatures is the balance between the high mechanical friction of the engine and the low energy density of the combustible mixture fed to the engine from the rich combustor.« less

  • Alcohol fuels exhibit poor cold-start performance because of their low volatility. Neat alcohol engines become difficult, if not impossible, to start at temperatures close to or below freezing. Improvements in the cold-start performance (both time to start and emissions) are essential to capture the full benefits of alcohols as an alternative transportation fuel. The objective of this project was to develop a neat alcohol partial oxidation (POX) reforming technology to improve an alcohol engine`s ability to start at low temperatures (as low as {minus}30 C) and to reduce its cold-start emissions. The project emphasis was on fuel-grade ethanol (E95) butmore » the technology can be easily extended to other alcohol fuels. Ultimately a compact, on-vehicle, ethanol POX reactor was developed as a fuel system component to produce a hydrogen-rich, fuel-gas mixture for cold starts. The POX reactor is an easily controllable combustion device that allows flexibility during engine startup even in the most extreme conditions. It is a small device that is mounted directly onto the engine intake manifold. The gaseous fuel products (or reformate) from the POX reactor exit the chamber and enter the intake manifold, either replacing or supplementing the standard ethanol fuel consumed during an engine start. The combustion of the reformate during startup can reduce engine start time and tail-pipe emissions.« less

  • ;
    The report provides the results from a program to evaluate a set of heated fuel injectors on an M100-fueled vehicle in an attempt to lower cold start emissions of unburned fuel and carbon monoxide and to improve cold startability and driveability. This technology was evaluated at several different temperatures.

  • ; ; ; ...
    A late-model vehicle was converted to operate using methanol, gasoline, or ethanol as fuel and experimental work was done to obtain energy economy and exhaust emissions data for each of the three fuels. Results are compared at equal equivalence ratios both with and without an oxidation catalyst in the exhaust system. Using a catalyst for emissions control, unburned (hydro) carbon emissions were lowest during lean operating conditions and were nearly the same for all three fuels under those conditions. Oxides of nitrogen emissions typically were reduced by over 50% in changing from gasoline to methanol or ethanol. Detailed composition ofmore » the exhaust hydrocarbons was determined from analysis via gas chromatography. These data were used for calculating photochemical reactivities and comparisons were made among the fuels during cold start and FTP weighted tests. Gasoline exhaust was often calculated to have the lowest total reactivity during the FTP, however, methanol exhaust reactivity was lowest for the stoichiometric condition with catalyst. Aldehydes accounted for large fractions of the reactivity calculated for methanol and ethanol exhausts. Cold start emissions were of about equal reactivity for gasoline and methanol.« less

  • ;
    A test program was devised at EPA's National Vehicle and Fuel Emissions Laboratory to evaluate a Tonen ultrasonic fuel atomizer system on a Honda B20 engine using both M85 (85% methanol, 15% hydrocarbons) and M100 (neat methanol) fuels to determine whether cold starting a premixed-charge port injected engine on alcohol fuels at low ambient temperatures can be improved. Modification to the engine's intake manifold was performed at the Japanese Automotive Research Institute (JARI) in cooperation with the New Energy Development Organization (NEDO) to install heated injectors in close proximity to the ultrasonic atomizers. The engine is also equipped with themore » stock port injector system intact and functional. Successful M100 cold starts were obtained down to 20 deg F (-7 deg C).« less