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ORC(有机朗肯循环)是实现中低温热源热功转换的关键技术.以R245fa为工质,采用单螺杆膨胀机,在120℃不稳定热源下实验研究了ORC发电系统在变负载下的动态运行特性及系统主要运行参数随波动热源的变化.实验结果表明:增大负载容量,维持膨胀机做功状态所需工质流量增加,膨胀机入口压力变大,单位工质吸热量变小,膨胀机入口温度及过热度降低.但由于系统整体吸热量变大,系统冷凝压力及冷却水入口温度就增加.系统的发电功率与效率也随负载的提升而不断增大,最大分别为4.61 kW与5.76％.受热源温度正弦波动的作用,系统主要运行参数出现不同程度的波动,冷凝压力的变化是造成系统不稳定的主要原因.“,”ORC (organic Rankine cycle) is regarded as the key technology to convert low grade heat into work.The dynamic test of an ORC with R245fa as the working fluid was presented in this paper.The operating parameters of the system were analyzed under unsteady heat source with average temperature of 120 ℃.The experimental results showed that with the increase of load capacity,the mass flow rate of the working fluid as well as the expander inlet pressure had to increase to maintain the constant expander speed.As the load increased,the heat absorption of unit working fluid was decreased,but the overall heat absorption was increased.Thus,the inlet temperature and superheating of the expander were decreased but the condensing pressure and cooling water inlet temperature were increased.The generated electric power and electrical efficiency were increased with the increase of load.The maximum generated power and electrical efficiency were 4.61 kW and 5.76％,respectively.Due to the temperature fluctuation of heat source,the ORC system operating parameters fluctuated slightly with time.The main reason for the instability of the system was the variation of condensing pressure.