分循环膨胀发动机换气参数影响规律研究

Research on the Influence Rule of Air Exchange Parameters of Split Cycle Expansion Engine(SCEE)

以分循环膨胀发动机(split cycle expansion engine,SCEE)为研究对象开展了膨胀缸换气参数影响规律的研究,为高效率发动机的设计与优化提供指导。结果表明:膨胀缸进气门升程降低使得膨胀缸进气压力增大,同时燃烧缸泵气损失增大,进气门升程由6 mm降到1 mm时,系统指示热效率最多降低5.83%。膨胀缸排气门升程降低将使得高压气罐压力上升,同时膨胀缸压缩过程耗功增加,压缩过程耗功占主导,排气门升程由8 mm降到3 mm时,系统指示热效率最大降低2.80%。膨胀缸排气门关闭角的提前将增大膨胀缸进气压力及膨胀缸入口处压力损失,当膨胀缸排气门关闭角为10°时二者可获得较好折中,系统指示热效率为47.78%。膨胀缸排气门开启角的推迟可以减少由过度膨胀导致的排气门处的倒流现象。

Taking a split cycle expansion engine(SCEE)as the research object,the influence rule of expansion cylinder air exchange parameters was studied,which provided a guidance for the design and optimization of high-efficiency engines.The results indicated that the reduction of intake valve lift increased the inlet pressure of the expansion cylinder and pumping loss of the combustion cylinder.When the intake valve lift was reduced from 6 mm to 1 mm,the indicated thermal efficiency was reduced by 5.83%at most.The reduction of the expansion cylinder exhaust valve lift increased the pressure of the high-pressure tank,and the power consumption in the compression process of the expansion cylinder increased.The effect of the power consumption of the expansion cylinder was dominant.When the exhaust valve lift was reduced from 8 mm to 3 mm,the indicated thermal efficiency decreased by 2.80%at most.The advance of the exhaust valve closing timing of the expansion cylinder increased the inlet pressure of the expansion cylinder and the pressure loss at the inlet of the expansion cylinder.A better trade-off was obtained when the exhaust valve closing timing was 10°,and the indicated thermal efficiency was 47.78%.The delay of the expansion cylinder exhaust valve opening timing reduced the backflow caused by excessive expansion.