Publications


Title정용진, 박성산, 배충식, 김득상, “디젤 엔진에서 분사시기 영향에 따른 질소 희석된 혼합기의 연소 가시화”, 2012 한국자동차공학회 학술대회 및 전시회, 2012. 5.

정용진, 박성산, 배충식, 김득상, “디젤 엔진에서 분사시기 영향에 따른 질소 희석된 혼합기의 연소 가시화”, 2012 한국자동차공학회 학술대회 및 전시회, 2012. 5.

Abstract

Exhaust gas recirculation and charge dilution with nitrogen were used to implement low temperature combustion with early injection in metal and optical engines, respectively. Based on the results of soot and NOx emissions in a metal engine test, in-cylinder visualization is focused on a region of simultaneous reduction in soot and NOx emissions. For injection timing of 20° crank angle (CA) before top dead center (BTDC), relatively high oxygen concentration condition showed two peaks of natural luminosity; one corresponds the OH chemiluminescence from high temperature heat release in periphery of piston bowl, and the another coincides with soot luminescence in diffusive flame. Both peaks are reduced as oxygen concentration at intake stream decrease, however, the luminosity corresponding to the diffusive flame is not apparent below a certain oxygen concentration. For injection timing of 30° CA BTDC with oxygen concentration being similar to that of 20° CA BTDC, the luminosity is weak for OH chemiluminescence and no apparent for soot luminescence. The earlier injection timing allows mixing period to prolong, thus relatively well-premixed charge resulted in reduction of soot particles. This result is also supported by the longer ignition delay calculated from the metal engine test.

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