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以亚临界有机朗肯简单循环为研究对象,理论分析得到影响系统性能的独立变量;膨胀机进口温度、进口压力、冷凝温度和热源出口温度.当给定冷凝温度且以蒸发器窄点温差为约束变量时,独立变量减少为膨胀机进口温度和进口压力.在此基础上,以耦合低温热源时的系统热效率作为评价指标,对8种常用有机工质的亚临界简单系统性能的变化规律进行分析,得到循环系统全局最优性能的运行参数.结果表明:系统热效率由循环热效率和热源效率共同决定;采用有机工质R236fa、R123和R236ea的循环热效率相对较高;由于热源的耦合作用,采用有机工质R236fa、RC318和R236ea的系统热效率相对较高.“,”The independent performance variables including expander inlet temperature and pressure,condensing temperature,and outlet temperature of heat source are theoretically obtained for the subcritical simple organic Rankine cycle (ORC).When the condensing temperature is given and evaporator pinch temperature difference is constrained,the independent variables are reduced to expander inlet temperature and pressure.Based on the above analysis results,optimal working conditions of 8 working fluids for global maximum system thermal efficiency of the subcritical simple ORC coupled with low-temperature heat source are investigated.The results show that system thermal efficiency is decided by both cycle thermal efficiency and heat source efficiency.The cycle thermal efficiency is higher for the working fluids R236fa,R123 and R236ea,but the system thermal efficiency is higher for the working fluids R236fa,RC318 and Rl14 due to the coupling effect of the heat source.