不同海拔下柴油机氧化催化器与选择性催化还原系统对柴油机性能与排放的影响

Effects of Diesel Oxidation Catalyst and Selective Catalytic Reduction System on Diesel Engine Performance at Different Altitudes

基于柴油机高原试验台架,在80 kPa、90 kPa、100 kPa大气压力下进行了柴油机外特性试验,研究了不同海拔下加装柴油机氧化催化器(diesel oxidation catalyst,DOC)与选择性催化还原(selective catalytic reduction,SCR)系统对柴油机的进排气参数、动力性、经济性、燃烧性能及排放特性的影响。研究结果表明,加装DOC+SCR会使进气流量下降,排气背压升高,功率和转矩下降,油耗升高,排气温度升高,排气流量下降,而HC、CO、NO_(x)与碳烟等污染物排放显著下降。不同海拔下加装DOC+SCR的影响程度也有所差异,尤其是对排气温度、排气背压、有效燃油消耗率与SCR转化效率的影响最为显著。加装DOC+SCR后,80 kPa、90 kPa、100 kPa下的排气温度分别平均升高7.35%、7.21%、7.11%;排气背压分别平均升高28.02%、27.08%、26.81%;有效燃油消耗率分别平均升高1.64%、2.87%、2.94%;外特性工况下SCR最大转化效率分别为88.86%、86.11%、84.76%。

Based on the plateau test rig of diesel engine,the external characteristic test of diesel engine was carried out under the atmospheric pressure of 80 kPa,90 kPa and 100 kPa.The changes of intake and exhaust state parameters,power performance,fuel economy,combustion performance and emission characteristics of diesel engine with diesel oxidation catalyst(DOC)and selective catalytic reduction(SCR)were studied.The results show that the addition of DOC+SCR can reduce the intake mass flow,exhaust back pressure,engine power and torque,fuel consumption,exhaust temperature,exhaust mass flow,and HC,CO,NO_(x) and smoke emissions.The influences of DOC+SCR at different altitudes are also different,especially for exhaust temperature,exhaust back pressure,BFSC and SCR conversion efficiency.After adding DOC and SCR,the exhaust temperatures at 80 kPa,90 kPa and 100 kPa increased by 7.35%,7.21%and 7.11%respectively.The exhaust back pressures increased by 28.02%,27.08%and 26.81%on average,respectively.The effective fuel consumption rates increased by 1.64%,2.87%and 2.94%on average,respectively.The maximum conversion efficiencies of SCR under external characteristic conditions were 88.86%,86.11%and 84.76%,respectively.