【摘要】 对采用朗肯循环的小型车用汽油机排气余热回收系统进行了研究,通过发动机排气能量分析发现,在主要运行工况内,通过排气带走的能量占所消耗燃料能量的25%～40%,排气温度为500～750,℃,具有较高的回收潜力.分析了工质流量及蒸发压力对系统工作性能的影响,结果表明,对汽油机排气余热回收系统所允许工质流量较小,蒸发压力变化范围较窄.换热器效率主要受工质流量的影响,而朗肯循环的效率则主要取决于蒸发压力.在发动机负荷较低时,选择较小的蒸发压力可以拓宽工质流量范围,保证系统稳定运行;而在高负荷时,选择较高的蒸发压力可以提高系统效率.基于所选用的螺旋管式蒸发器在Matlab中建立了系统模型,根据模拟结果预测,采用朗肯循环回收排气能量,能将该汽油机热效率提高3%～8%.更多还原

【Abstract】 Exhaust energy recovery(EER)from a light-duty gasoline engine using steam Rankine cycle were investigated.Experimental results show that the fraction of exhaust energy accounts for 25% to 40% of the total heat release.High recovery potential of exhaust energy is possible for gas temperature of 500— 750,℃.Effect of working fluid parameters on system performance was analyzed.Flow rate has a significant influence on heat exchanger efficiency,while Rankine cycle efficiency is mainly determined by the evaporation pressure.Low evaporation pressure is regulated to maintain stable and efficient EER system under low load.Simulation shows that EER system increases engine fuel conversion efficiency by 3% to 8%.更多还原