엔진 운전변수가 가스연료 엔진의 HC 배출물에 미치는 영향

Abstract

Measurements of the concentrations of individual exhaust hydrocarbon species have been made under various engine operating in a 2-liter 4-cylinder engine for natural gas and LPG. Tests were performed at constant engine speed, 1800 rpm for two compression ratios(8.6 and 10.6), with various operating parameters, such as excess air ratio(l.O-1.6), bmeps(250-800 kPa) and spark timings(BTDC 10-55). It was found that the natural gas gave the less ozone formation than LPG in various operating conditions. This was ccomplished by reducing the emissions of propylene(C3Hs),which has relatively high MIR factor, and propane(C3Hg) that originally has large portion of LPG. In addition, the natural gas show lower values in the SR and BSRs. Higher compression ratio showed higher NMHC emissions. However, SR decreased since fuel species of HC emissions increase.BSRs showed almost same values under high bmep, over 5OOkPa for both fiels. This means that effect of increasing of NMHC emissions and effect of decreasing of SRs with higher bmep affect each other simultaneously. With advanced spark timing, BSRs of LPG were increased while those of natural gas showed almost constant values.