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화학반응수치해석을 이용한 HCCI기관의 예혼합기의 성층화성이 연소시의 압력 상승률에 미치는 영향
임옥택(Ocktaeck LIM),박규열(Kyuyoel Park),백영순(Youngsoon Baek),표영덕(Youngduk Pyo) 한국가스학회 2009 한국가스학회 학술대회논문집 Vol.2009 No.4
The HCCI engine is prospective internal combustion engine, which is capable of providing both high diesel-like efficiencies and very low NOx and particulate emissions. However, several technical issues must be resolved before an HCCI engine can be used as widespread application. One of issues is that its operating range is limited by an excessive pressure rise rate which is caused by excessive heat release because of its self-accelerated combustion reaction and the resulting engine knock in high-load region. The purpose of this study is to evaluate the potential of thermal and fuel stratification for reducing pressure rise rate in an HCCI engine. The concentration of NOx and CO in exhaust gas is also evaluated to confirm the combustion completeness and NOx emission. The computational work is conducted using a multi-zone code with detailed chemical kinetics, including the effects of thermal and fuel stratification on the onset of ignition and the rate of combustion.
이차원발광화상계측에 의한 예혼합압축자기착화연소의 연소실내 혼합기의 불균질성에 관한 연구
임옥택(Ocktaeck Lim),노리마사 이이다(Norimasa Iida) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.12
HCCI엔진에는 농도성층화와 열적성층화가 존재하고, 이것들은 착화와 연소과정에 영향을 미치고 있다. 본 연구에서는 예혼합기의 불균질성이 HCCI연소과정에 미치는 영향에 대해서 조사하였다. 우선 4행정광학엔진을 이용하여 잔류가스가 있는 경우와 급속압축장치를 이용하여 잔류가스가 없는 경우의 예혼합기의 불균질성에 대하여 비교분석하였다. DME를 연료로 이용하고 프래밍카메라를 사용하여 2차원화학발광이미지를 취득하였다. 그 결과, 잔류가스가 있는 불균질 한 경우에 4행정엔진실험에서는 연소현상이 공간적으로 연소현상의 시간차이가 발생하였다. 잔류가스가 없는 급속압축장치의 실험에서는 4행정기관의 결과에 비해서 더 적은 공간적인 변화가 존재하는 것을 알 수 있었다. Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.