抽气回热式有机朗肯循环系统热力学分析

Thermodynamic Analysis of Regenerative Organic Rankine Cycle

为了实现发动机排气余热能的高效回收与利用,设计了抽气回热式有机朗肯循环(ORC)系统。在Matlab环境下,分析了抽气压力、蒸发压力、膨胀机入口温度等因素对系统性能的影响,并利用热力学第一定律及第二定律将抽气回热式ORC和基本ORC进行对比。研究结果表明,在固定蒸发压力下,抽气回热式ORC系统的热效率、效率随抽气压力的增大而先增大后减小,工质质量流量随抽气压力的增大而逐渐增大,蒸发器换热量随抽气压力的增大先减小后增大;与基本ORC系统相比,抽气回热式ORC系统的热效率、效率均有提高,损率降低,因此抽气回热式ORC系统余热回收效果更明显。

A regenerative organic Rankine cycle （ORC） system was designed to recover and utilize the waste heat energy from engine exhaust gas efficiently. The mathematical model of regenerative ORC was built up in Matlab and the influences of the factors such as suction pressure, evaporating pressure and expander inlet temperature on system performance were analyzed. Then the regenerative ORC was compared with the basic ORC by using a combined first and second law analysis. According to the results, when the evaporating pressure remained constant, the regenerative ORC system thermal efficiency and exergy efficiency would increase at first, then decrease with the increasing of suction pressure. The mass flow rate increased while the heat transfer rate in the evaporator decreased first and then increased with the increasing of suction pressure. By comparing the two configurations, it was seen that regenerative ORC produced higher efficiency with a lower irreversibility and could recover waste heat energy more effectively.