提出了一种回收烟气余热的耦合跨临界与亚临界有机朗肯循环系统,并进行了详细的性能分析。结果表明,该系统可以使膨胀机压比和进口压力降低,工质的选择更加灵活;当中间换热器节点温差小于某一临界值时,耦合系统的热力学性能要优于单级跨临界有机朗肯循环,且存在一个最佳节点温差使得系统发电成本最低;随着工质临界温度的增加,耦合系统的热力学性能会得到改善;使用等熵工质时系统性能要优于使用干工质时系统性能。 A coupled transcritical and subcritical organic Rankine cycle system for recovering waste heat from flue gas is proposed and a detailed performance analysis is carried out. The results show that the system can reduce the pressure ratio of the expander and the inlet pressure, and the choice of working fluid is more flexible. When the temperature difference of the intermediate heat exchanger is less than a certain critical value, the thermodynamic performance of the coupled system is better than that of the single-stage transcritical organic Rankine cycle, and there is an optimal node temperature difference to make the system generate the lowest cost. As the critical temperature of working fluid increases, the thermodynamic performance of the coupled system will be improved. When using isentropic working fluid, the system performance is better than that of using dry working fluid When the system performance.