Publications


Title김재헌, 배충식, "Late Intake Valve Closing (LIVC) 전략이 DME 압축착화 엔진 연소에 미치는 영향", 2012 한국자동차공학회 학술대회 및 전시회, 2012. 5.

김재헌, 배충식, “Late Intake Valve Closing (LIVC) 전략이 DME 압축착화 엔진 연소에 미치는 영향”, 2012 한국자동차공학회 학술대회 및 전시회, 2012. 5.

Abstract

The effective compression ratio reduction by means of late intake valve closing (LIVC) strategy was applied in a DME compression ignition engine to investigate its potential effects on the engine performance and emissions. The single injection timing of the DME was varied through the beginning of the compression to the end of compression stroke. The DME was injected directly into the cylinder with an injection pressure of 60 MPa. Two different intake valve closing (IVC) conditions were investigated, namely base IVC timing of 28 deg ABDC (after bottom dead center) and LIVC timing of 43.9 deg ABDC.
The IMEP characteristics with respect to the injection timing at two different IVC timings showed a similar trend with only a phase shift towards the advanced injection timing. The reduction in the compression ratio had resulted in lower compression pressure and temperature than those of base IVC timing, so the ignition delay was increased and the overall heat release rate was retarded to the later crank angle. The combustion duration was also lengthened for the LIVC timing due to the reduced magnitude of heat release rate and reduced in-cylinder temperature.
The NOx emission was reduced by 10% due to the reduced in-cylinder combustion temperature. The prolonged ignition delay which enhanced the mixture homogeneity was also considered to contribute on the reduction of NOx emission. It showed potentials that the NOx emissions can be reduced while maintaining the engine power output through LIVC strategy. The HC and CO was low at the injection timing where the NOx emission was the maximum due to the high temperature atmosphere for the oxidation of HC and CO. The soot formation was low due to the intrinsic characteristics of DME, and the effect of IVC timing on soot variation was not clearly observed.
The maximum pressure rise rate was lower for the LIVC timing condition. Prolonged combustion period and reduced magnitude of heat release rate caused a slower pressure rise. However, the absolute value of the maximum pressure rise rate was still high due to the single injection, and it needs to be further improved.

Previous박성산, 정용진, 배충식, “협각 인젝터를 이용한 예혼합 압축착화 연소에서의 디젤 노킹 가시화”, 제 44회 KOSCO Symposium 초록집, pp101-104, 2012. 4.
Next정용진, 박성산, 배충식, 김득상, “디젤 엔진에서 분사시기 영향에 따른 질소 희석된 혼합기의 연소 가시화”, 2012 한국자동차공학회 학술대회 및 전시회, 2012. 5.
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