发动机两级有机朗肯循环尾气余热回收系统的研究

摘要

针对汽车发动机排出尾气余热的特点，设计了两级有机朗肯循环（O RC ）尾气余热回收系统，采用单螺杆膨胀机输出动力。以R245fa作为循环工质，在不同的蒸发温度和膨胀比条件下，对两级有机朗肯循环系统和基本有机朗肯循环系统的热力性能进行了分析和比较。研究结果表明，两级有机朗肯循环系统具有更高的热效率和效率，且损率更低，对于发动机尾气余热的回收效果更好。%According to the characteristics of waste heat from engine exhaust gas ,the waste heat recovery system based on two-stage organic Rankine cycle (ORC) was designed and its power was delivered by single screw expanders .Under different evaporation temperatures and expansion ratios ,the thermodynamics performance of two-stage ORC system and basic ORC sys-tem operated with R245fa medium were analyzed and compared .The results show that the two-stage ORC system has higher thermal efficiency ,higher exergy efficiency ,lower exergy loss rate and hence a better performance of waste heat recovery .