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Dimethyl Ether 예혼합 압축 착화 엔진에서 흡기중 CO<sub>2</sub> 농도와 흡기온도 변화가 연소에 미치는 영향
배충식,장진영,염기태,Bae, Choong-Sik,Jang, Jin-Young,Yeom, Ki-Tae 대한기계학회 2007 大韓機械學會論文集B Vol.31 No.6
This study focused on the effects of the $CO_2$ gas concentration in fresh charge and induction air temperature on the combustion characteristics of homogeneous charge compression ignition with dimethyl ether (DME) fuel, which was injected at the intake port. Because of adding $CO_2$ in fresh charge, start of auto-ignition was retarded and bum duration became longer. Indicated combustion efficiency and exhaust gas emission were found to be worse due to the incomplete combustion. Partial burn was observed at the high concentration of $CO_2$ in fresh charge with low temperature of induction air. However, indicated thermal efficiency was improved due to increased expansion work by late ignition and prolonged bum duration. Start of auto-ignition timing was advanced with negligible change of burn duration, as induction air temperature increased. Burn duration was mainly affected by oxygen mole concentration in induction mixture. Bum duration was increased, as oxygen mole concentration was decreased.
가솔린 엔진에서 배기 온도 저감을 위한 열교환기 설계 최적화
이석환,박정서,배충식,Lee, Seok-Hwan,Park, Jung-Seo,Bae, Choong-Sik 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.3
Design of experiments (DOE) technique has been used to design an exhaust heat exchanger to reduce the exhaust gas temperature under high load conditions in a spark-ignition engine. The DOE evaluates the influence and the interaction of a selected eight design parameters of the heat exchanger affecting the cooling performance of the exhaust gas through a limited number of experiments. The heat exchanger was installed between the exhaust manifold and the inlet of the close-coupled catalytic converter (CCC) to reduce thermal aging. To maximize the heat transfer between exhaust gas and coolant, fins were implemented at the inner surface of the heat exchanger. The design parameters consist of the fin geometry (length, thickness, arrangement, and number of fin), coolant direction, heat exchanger wall thickness, and the length of the heat exchanger. The acceptable range of each design parameter is discussed by analyzing the DOE results.