基于热力学第二定律的有机朗肯循环效能分析

Efficiency analysis of organic Rankine cycle based on the second law of thermodynamics

利用烟气余热驱动有机朗肯循环,可以实现对其余热的综合梯级高效利用。以100℃~150℃烟气余热高效梯级利用为研究目标,综合考虑工质的热物性、安全性和环保性的影响,选取R113,R123,R11,R141b,R600,R245fa六种制冷剂作为有机朗肯循环的工质。基于热力学第二定律分析了六种工质参与的简单有机朗肯循环的效能,研究了热源温度对系统循环性能参数的影响。研究表明,有机朗肯循环的不可逆损失主要集中在蒸发器和膨胀机部分,冷凝器和水泵的损失较小,基本可以忽略;蒸发器部分损失最大,基本达到了总不可逆损失的一半。

The organic Rankine cycle driven by the waste heat of flue gas can realize the comprehensive stepped utilization of the waste heat. To aim for the utilization of 100℃ - 150℃ waste heat and based on comprehensive consideration of the thermo-physical properties, safety and environmental impacts of organic compound, these refrigerants of R123, R141 b, R245fa, R245c, R601 and R601 were selected as working substances. The efficiency of simple organic Rankine cycle participated by six kinds of refrigerant was anslysed based on the second law of thermodynamics, the effect of heat source temperature on the cycle perform- ance parameters of the system is studied. It indicates that the irreversible loss of organic Rankine cycle mainly concentrates in the expander and the evaporator, the losses of condenser and pump are small and can be ignored. The irreversible loss of evaporator is the largest, which basically reaches half of the total irreversible loss.