汽油/柴油双燃料HPCC在不同转速下的高负荷研究

Study on High Load of HPCC Fuelled with Gasoline/Diesel Dual Fuel at Different Engine Speeds

在一台改造的单缸柴油机上研究了汽油/柴油双燃料高比例预混合燃烧(HPCC)模式,其中汽油由进气道喷射,柴油采用缸内直喷并引燃预混合气.以1,600,r/min为例,分析了影响负荷扩展的运行参数,通过增加油量并优化各运行参数直至达到如下限定条件即得出900～2,500,r/min下的高负荷优化点:NOx排放≤0.4,g/(kW.h)、Soot排放≤0.01,g/(kW.h)、MPRR(最大压升率)≤1,MPa/°CA以及COVIMEP(平均指示压力循环波动系数)≤10%.高负荷优化点的平均指示压力(IMEP)值在低、中和高转速下分别受NOx排放、MPRR及最大暴发压力的限制,且随着转速的升高而增大,在2,300,r/min获得最大值1.2,MPa.指示油耗率在1,900,r/min获得最低值为169,g/(kW.h).

The highly premixed charge combustion （HPCC） fuelled with gasoline/diesel dual fuel in a modified single-cylinder diesel engine was studied. The in-cylinder fuel blending with intake air port fuel injection of gasoline and direct injection of diesel fuel is proposed as the fuel blending strategy and the diesel serves as the ignition source. At engine speed of 1 600 r/min, the influences of operating parameters on extending higher load were analyzed. To obtain the optimal points of high load at engine speeds of 900 to 2 500 r/min with HPCC mode, the experiments were carried out on different engine speeds and engine load is increased with increasing fuel mass and optimizing the operating parameters until predefined limits were reached. These predefined limits are the emissions of NOx less than 0.4 g/（kWh） and Soot less than 0.01 g/（kWh）, the maximal pressure rise rate （MPRR）lower than 1 MPa/°CA and coefficient of vari- able of IMEP （COVIMEP） lower than 10%. Results show that the limits of the optimal high load IMEP at low, middle and high speeds are restricted by the high values of NOx emissions, MPRR and peak cylinder pressure, respectively. Furthermore, the IMEP is increased with the increase of speed and reaches the maximum value of 1.2 MPa. The lowest ISFC value of 169 g/（kW·h）was obtained at 1 900 r/min.