天然气/柴油双燃料发动机不同天然气供给量计算方法及试验研究

Experimental Study on Calculation Methods of Natural Gas Supply for Natural Gas-Diesel Dual Fuel Engine

基于试验的方法研究等热值法、理论等空气消耗量法和实际等空气消耗量法3种不同的计算方法对发动机动力性、经济性及排放特性的影响。试验结果表明:等热值法和理论等空气消耗量法对发动机的性能影响差异较小,各工况差异低于5%。实际等空气消耗量法确定的天然气供给量能明显提升发动机动力性,平均增加动力42.33%。不同天然气供给量计算方法在未对燃料供给进行优化时,未能有效降低发动机有效燃料消耗率,在大负荷工况有效燃料消耗率偏差平均为6.85%。双燃料模式下NOx排放得到明显改善,HC+NOx排放在中、高负荷工况时能满足排放限值要求,CO排放在低转速工况满足排放限值要求。

The effects of three methods of calculating natural gas(NG)supply on engine power,fuel economy and emissions characteristics were investigated experimentally.The results reveal that the influences of the equal calorific method(ECM)and the stoichiometrical ratio-equal air consumption method(SR-EACM)on the engine performance are relatively slight,and the differences are less than 5% at all working conditions.The actual air fuel ratio-equal air consumption method(AEACM)can obviously improve the engine power with an average increase of 42.33%in power output.As the fuel supply system is not optimized,the brake specific fuel consumption can't be curbed effectively with the three methods.Moreover,with dual fuel working model,NOxemissions are significantly decreased and the level of HC+NOxemissions at medium and heavy load conditions meets the regulation requirements.Also,the emission of CO at low speed conditions meets the requirements.