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Proceedings ArticleDOI

Effect of compression ratio on exhaust emissions and performance of a methanol-fueled single-cylinder engine

01 Feb 1977-Vol. 19
TL;DR: In this paper, a methanol-fueled single-cylinder engine was run at compression ratio (CR) from 8 to 18, and engine speed and airflow were constant at 1200 rpm and about half throttle, respectively; equivalence ratio (phi) was varied from 0.7 to 1.1; and spark timing from best power (MBT) to 10/sup 0/ retarded.
Abstract: One of the reasons methanol is considered an attractive alternative fuel for automobiles is its high octane quality, which may allow the use of high compression ratio (CR) engines. To evaluate compromises between engine efficiency and exhaust emissions, a methanol-fueled single-cylinder engine was run at CR's from 8 to 18. At each CR, engine speed and airflow were constant at 1200 rpm and about half throttle, respectively; equivalence ratio (phi) was varied from 0.7 to 1.1; and spark timing was varied from best power (MBT) to 10/sup 0/ retarded. Knock was observed only at CR = 18 with MBT spark timing. Increasing CR from 8 to 18 while maintaining MBT spark timing increased efficiency about 16%, but also increased NO/sub x/ and unburned fuel (UBF) emissions. Some previous studies have reported decreased NO/sub x/ emissions with increased CR, possibly because MBT spark timing was not maintained. Results of this study indicate that constant NO/sub x/ emissions can be maintained by retarding spark timing while increasing CR to improve efficiency. Retarding spark timing, however, only marginally reduced UBF emissions. Vehicle tests are necessary to define the optimum CR for methanol fueling because exhaust emission trends and knocking tendency may be differentmore » than those observed with this single-cylinder engine.« less
Citations
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Journal ArticleDOI
01 Aug 1998
TL;DR: In this paper, alcohols with carbon numbers ranging from C1 to C5 were individually blended with unleaded test gasoline and all the alcohol-gasoline blends had the same oxygen mass content.
Abstract: Alcohols with carbon numbers ranging from C1 to C5 were individually blended with unleaded test gasoline. All the alcohol-gasoline blends had the same oxygen mass content. The performance c...

175 citations

Proceedings ArticleDOI
21 Oct 2002
TL;DR: In this article, the authors used a turbocharged, PFI spark-ignited 1.9L, 4-cylinder engine with 19.5:1 compression ratio and achieved better than 40% brake thermal efficiency from 6.5 bar BMEP at speeds ranging from 1200 to 3500 rpm.
Abstract: Ongoing work with methanol- and ethanol-fueled engines at the EPA’s National Vehicle and Fuel Emissions Laboratory has demonstrated improved brake thermal efficiencies over the baseline diesel engine and low steady state NOx, HC and CO, along with inherently low PM emissions. In addition, the engine is expected to have significant system cost advantages compared with a similar diesel, mainly by virtue of its low-pressure port fuel injection (PFI) system. While recognizing the considerable challenge associated with cold start, the alcohol-fueled engine nonetheless offers the advantages of being a more efficient, cleaner alternative to gasoline and diesel engines. The unique EPA engine used for this work is a turbocharged, PFI spark-ignited 1.9L, 4-cylinder engine with 19.5:1 compression ratio. The engine operates unthrottled using stoichiometric fueling from full power to near idle conditions, using exhaust gas recirculation (EGR) and intake manifold pressure to modulate engine load. As a result, the engine, operating on methanol fuel, demonstrates better than 40% brake thermal efficiency from 6.5 to 15 bar BMEP at speeds ranging from 1200 to 3500 rpm, while achieving low steady state emissions using conventional aftertreatment strategies. Similar emissions levels were realized with ethanol fuel, but with slightly higher BSFC due to reduced spark authority at this compression ratio. These characteristics make the engine attractive for hybrid vehicle applications, for which it was initially developed, yet the significant expansion of the high-efficiency islands suggest that it may have broader appeal to conventional powertrain systems. With further refinement, this clean, more efficient and less expensive alternative to today’s petroleum-based IC engines should be considered as a bridging technology to the possible future of hydrogen as a transportation fuel.

127 citations


Cites background or methods from "Effect of compression ratio on exha..."

  • ...Earlier works with single-cylinder SI methanol engines [5], for example, showed 16% improvement in brake efficiency when raising the compression ratio from 8....

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  • ...Benefits such as higher efficiency and specific power and lower emissions may be realized with alcohols: their high octane number gives the ability to operate at higher compression ratio without preignition [5]; their greater latent heat of vaporization gives a higher charge density [1-3, 6]; and their higher laminar flame speed allows them to be run with leaner, or more dilute, air/fuel mixtures [7]....

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Journal ArticleDOI
Fangxi Xie1, Xiaoping Li1, Yan Su1, Wei Hong1, Jiang Beiping1, Liwei Han 
TL;DR: In this paper, the effect of three dilution substances, including air, cooled EGR and hot EGR on the engine combustion, performance and emissions was experimentally investigated at a port-injection spark ignition methanol engine which was modified from a diesel engine.

56 citations

Journal ArticleDOI
Fangxi Xie1, Xiaoping Li1, Wang Xinchao1, Yan Su1, Wei Hong1 
TL;DR: Using EGR and spark timing to control load of a spark-ignition methanol engine with wide open throttle (WOT) and stoichiometric mixture have been investigated experimentally, and its performance and emission characteristics were compared with the traditional control method by throttle.

53 citations


Cites background from "Effect of compression ratio on exha..."

  • ...without knock [11]; the evaporation heat of methanol is 3e5 times higher than that of gasoline, which makes the temperature of the intake manifolds lower, and increases the volumetric efficiency [12]....

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References
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Book
01 Feb 1974
TL;DR: A review of some basic statistical concepts some intermediate data analysis concepts A Scientific Approach to Experimentation Completely Randomized Design (CRD) Randomized Complete Block Design (RCBD) Nested (Hierarchical) and Nested Factorial Designs Split Plot Type Design Latin Square Type Designs 2n Factorial Experiments (Complete and Incomplete Blocks) Fractional Factorial Experimentations for Two-Leveled Factors Three-Level Factorial Experience (FFE) Mixed FactorialExperiments and Other Incomplete Block Designs Response Surface Exploration Appendices
Abstract: Review of Some Basic Statistical Concepts Some Intermediate Data Analysis Concepts A Scientific Approach to Experimentation Completely Randomized Design (CRD) Randomized Complete Block Design (RCBD) Nested (Hierarchical) and Nested Factorial Designs Split Plot Type Design Latin Square Type Designs 2n Factorial Experiments (Complete and Incomplete Blocks) Fractional Factorial Experiments for Two-Leveled Factors Three-Level Factorial Experiments Mixed Factorial Experiments and Other Incomplete Block Designs Response Surface Exploration Appendices

429 citations

Journal ArticleDOI
TL;DR: In this paper, the authors applied the method of Lavoie el al. to a spark-ignited carburetted IC engine and incorporated into the computer program the engine variables; fuel type, fuel air equivalence ratio, humidity content of inlet air, % exhaust gas recirculation, inlet manifold temperature, manifold pressure, RPM, compression ratio, piston connecting rod to crank ratio, and duration and position of combustion in the cycle.
Abstract: Lavoie, Heywood and Keck (1970) have recently shown how one can calculate the amount of NO formed during the combustion and subsequent expansion stroke of an IC engine. In this paper we have applied the method of Lavoie el al. to a spark-ignited carburetted IC engine and have incorporated into the computer program the engine variables; fuel type, fuel air equivalence ratio, humidity content of inlet air, % exhaust gas recirculation, inlet manifold temperature, inlet manifold pressure, RPM, compression ratio, piston connecting rod to crank ratio, and duration and position of combustion in the cycle. In addition to NO, we calculate indicated mean effective pressure and indicated specific fuel consumption. Brake specific values are calculated from an empirical correlation. Calculated NO levels show good agreement with data in the literature for the effect of the variables of air-fuel ratio, manifold pressure, spark timing, and humidity. Control methods capable of reducing NO emissions to the 100 ppm...

165 citations

Proceedings ArticleDOI
01 Feb 1976
TL;DR: In this paper, the relationship of compression ratio on fuel energy conservation with the constraint of the 1977 Federal emission standards (15 HC, 150 CO and 20 NOX) was evaluated.
Abstract: This paper describes the results of a study to evaluate the relationship of compression ratio on fuel energy conservation with the constraint of the 1977 Federal emission standards (15 HC, 150 CO and 20 NOX) The influence of the energy losses in the refinery process to produce higher octane fuels was considered as well as the effect of compression ratio on engine efficiency Two different emission control systems were evaluated: a catalytic converter-EGR system and a manifold reactor-EGR system /GMRL/

13 citations

01 Sep 1975
TL;DR: A discussion of methanol as a safe, stable, nonpolluting fuel covers the availability of technology for its production from coal or from forest and farm wastes; suitability of Methanol for liquid-fuel motors, stratified-charge engines, turbines, and fuel cells.
Abstract: A discussion of methanol as a safe, stable, nonpolluting fuel covers the availability of technology for its production from coal or from forest and farm wastes; suitability of methanol for liquid-fuel motors, stratified-charge engines, turbines, and fuel cells; the drawback that methanol contains half the energy content of gasoline at nearly the same price ($0.38/gal retail); a UGI Corp. proposal to convert bituminous coal to 250 million gal/yr of methanol to be sold both to the chemical market and as a special premium fuel; Florida Power Corp.'s report of a 74% drop in nitrogen oxide emissions after substituting methanol for oil in a turbine; research by the automotive industry on gasoline-methanol blends and all-methanol engines; and a Mobil Oil Corp. pilot plant being built to produce gasoline from methanol.

6 citations