乙醇喷射定时对乙醇柴油双燃料发动机性能的影响

在具有双喷射系统的压燃式发动机中,用一个喷射系统喷射乙醇作为主燃料,另一个喷射柴油作为点火燃料,进行了不同乙醇喷射定时的性能试验和燃烧分析。结果表明,在上止点前21°CA喷射点火柴油时,乙醇可以先于柴油喷射,在上止点前25°CA喷射乙醇燃料时发动机的经济性能最佳,接近原柴油机水平,在上止点前29°CA左右喷射乙醇燃料时发动机具有较好的动力性;缸内的统计最大压力在小负荷时随着乙醇喷射定时提前而降低,在大负荷时随着乙醇喷射定时提前而提高;双燃料发动机的最大压力标准方差随着乙醇喷射定时提前而增大,并且工作循环的稳定性逐渐变差;当乙醇喷射定时在上止点前31°CA时双燃料发动机不能较好地稳定工作。

Effect of Ethanol Injection Timing on Ethanol-diesel Dual-fuel Engine Performance

In a direct injection compression ignition engine (CIE) with dual injection systems, the performance tests and the combustion analysis at varied ethanol injection timing were performed respectively, which with ethanol as the main fuel injected by one injection system and diesel fuel as the igniting fuel injected by another injection system. The test results show that with the igniting fuel injected at 21°CA BTDC, the ethanol fuel injection timing can be earlier than the ignition fuel injection timing. The fuel economy of dual-fuel CIE approaches to that of the baseline diesel engine when the ethanol fuel injection timing is 25°CA BTDC. The maximal power output corresponding to the ethanol injection timing is 29°CA BTDC. The maximum statistical in-cylinder combustion pressure of test engine decreases with the advance of the ethanol injection timing at light load conditions, but it increases with the injection advance at heavy load conditions. The combustion pressure standard deviation increases with the advance of the ethanol injection timing, and correspondingly, the engine operation becomes more and more unsteady. When the ethanol injection timing is advanced to 31° CA BTDC, the injected igniting diesel fuel can not ignite the main ethanol fuel reliably.