Combustion and Emission Characteristics According to the Fuel Injection Ratio of an Ultra-Lean LPG Direct Injection Engine

Cheolwoong Park, Taeyoung Kim, Gyubaek Cho and Janghee Lee
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Cheolwoong Park: Department of Engine Research, Environmental and Energy Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Taeyoung Kim: Department of Engine Research, Environmental and Energy Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Gyubaek Cho: Department of Engine Research, Environmental and Energy Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea
Janghee Lee: Department of Engine Research, Environmental and Energy Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, Korea

Energies, 2016, vol. 9, issue 11, 1-12

Abstract: The effect of the fuel injection ratio on the combustion and emission characteristics of stratified lean mixture combustion was investigated for a spray-guided liquefied petroleum gas (LPG) direct injection engine. Inter-injection spark-ignition combustion—a specially designed combustion strategy for LPG fuel derived from a two-staged injection—was employed to maximize the improvement in thermal efficiency when combustion stability is secured. When changing the fuel injection ratio, the optimum spark advance and fuel injection timings were experimentally determined to maximize the thermal efficiency based on sweeping timings. The optimum fuel injection ratio with the highest thermal efficiency (42.76%) and stable operation was 60%/40%, with the optimization of the spark advance and fuel injection timing, because of the locally rich mixture region in the recirculation zone. NO x emissions were at their highest level with a fuel injection ratio of 60%/40% because of the high combustion temperature, and the levels of total hydrocarbon and CO emissions with 50%/50% and 60%/40% fuel injection ratios were similar, whereas emissions at 70%/30% were significantly higher because of fuel wetting and the formation of over-lean mixture.

Keywords: liquefied petroleum gas (LPG) direct injection; ultra-lean combustion; spray-guided type combustion system; brake thermal efficiency; combustion stability; emissions (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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