运行工况对基础燃料均质压燃燃烧过程影响的试验研究

在一台经改装的单缸直喷式柴油机上进行了不同辛烷值基础燃料下发动机转速对均质压燃（HCCI）燃烧特性、工况范围和排放特性影响的试验研究。研究结果表明：发动机转速升高，不同辛烷值燃料着火燃烧时刻推迟，以曲轴转角计算的燃烧持续期延长，高辛烷值燃料的缸内最大爆发压力和缸内温度降低；在中间转速，HCCI实现的最高平均指示压力最大，高转速工况，最高平均指示压力降低；对于低辛烷值燃料，转速对燃烧效率影响不大，转速升高，指示热效率增大；对于高辛烷值燃料，转速升高燃烧效率降低，指示热效率在中间转速最高，高转速降低。排放测试表明，转速升高使得HCCI运转的HC和CO排放都升高，NOx排放则逐渐降低。

Experimental Study on the Effect of Operating Conditions on the HCCI Combustion Characteristics

Experimental study on the effect of operating conditions on the combustion and emissions char- acteristics and the operating region of homogeneous charge compression ignition(HCCI)was conducted on a modified single-cylinder,four stroke diesel engine using PRF fuels with various values of octane num- ber.The results showed that increasing engine speed would increase the ignition delay and the combustion duration.However,in the case of high octane number PRF fuel,increasing engine speed would decrease the maximum cylinder pressure and temperature.Maximum indicated mean effective pressure(IMEP)oc- curred at middle engine speed,while maximum IMEP decreased at high engine speed.For PRF fuel with low octane number,engine speed had little influence on combustion efficiency,but the indicated thermal efficiency(ITE)increased with the increase of engine speed.For PRF fuel with high octane number,the combustion efficiency decreased with the increase of engine speed,and the maximum ITE occurred at the middle engine speed.Emission results showed that with the increase of engine speed HC,CO concentra- tions are increased and NO_x concentration is decreased.