增压二甲醚发动机的参数优化

Parameter Optimization in a Turbocharged Engine Fuelled with Dimethyl Ether

采用几种不同技术参数的喷油器和喷油泵,在改造后的车用增压柴油机上进行燃用二甲醚性能优化试验,在冷、热状态下评价了二甲醚燃料发动机的输出扭矩、功率、燃油消耗率以及尾气排放情况,分析了不同燃料温度和技术参数的喷油泵及喷油器对发动机性能及其尾气排放量的影响.结果表明:当二甲醚燃料温度逐渐上升时,发动机的扭矩和功率明显下降;在相同功率且采用同一规格喷油泵时,发动机的喷油器喷孔越小,NOx排放量越高、排温越低及燃料经济性越好;泵体强度较大的P8500喷油泵更适合于二甲醚发动机,在保持发动机功率输出不变的条件下,采用柱塞直径12 mm的P8500喷油泵,同时匹配喷孔孔径0.43 mm的喷油器,可使发动机的燃油经济性与NOx排放达到较好的折中.

Experimental study was conducted with a vehicular turbocharged diesel engine operated with neat dimethyl ether. On the basis of the measured engine power, torque, brake specific fuel consumption （BSFC） and emissions, the effects of fuel temperature and technical specifications of high pressure pump and nozzle on the performance and emissions of dimethyl ether engine were investigated. The results show that the engine power and torque decrease with the increase of dimethyl ether temperature. At the same engine load, using a smaller nozzle orifice, NOx emission level is higher, and BSFC is lower. The high pressure pump of P8500 is more appropriate for the dimethyl ether engine because its pump body has a higher strength. Under the required engine power output, a good compromise for dimethyl ether fuel consumption and NOx emissions can be obtained using P8500 pump with the plunger diameter of 12 mm and a injector of （6×0.43） mm.