低温热源喷射式发电制冷复合系统的(火用)分析

摘要

Exergy analysis was carried out for a novel combined power and ejector refrigeration cycle driven by low-temperature heat sources based on the second law of thermodynamics, while a numerical simulation performed for the system using R600a as the working fluid. Results show that under typical heat source conditions such as the inlet temperature Ths=420 K, mass flow mhs =0.2 kg/s and generating temperature Tg =370 K, the system may produce 2.74 kW of net power output (Wnet), 11. 99 kW of refrigeration output (Qe), with an exergy efficiency ηexergy up to 25.83％ and energy utilization efficiency ηu up to 45.34％.The cycle exergy loss mainly occurs in the steam generator and ejector. When Tg increases, both Wnet and ηexergy drop slightly, whereas Qe and ηu show a trend of first increase and then decrease due to the variation of mass flow. The energy utilization efficiency ηu reaches maximum while Tg=370 K.%根据热力学第二定律,对一种新型低温热源喷射式发电制冷复合系统进行了(火用)分析,并以R600a作为工质对系统进行了仿真计算.结果表明:在热源入口温度为420 K、热源热水流量为0.2kg/s、热源蒸发温度为370 K的标准工况下,系统净发电量为2.74 kW,系统制冷量为11.99 kw,系统的(火用)效率达到25.83%,系统能量利用率为45.34%;系统(火用)损失主要发生在蒸汽发生器和喷射器中.在热源蒸发温度提高过程中,系统内部工质流量发生改变,导致系统净发电量和(火用)效率小幅下降,制冷量和能量利用率先增后降.当热源蒸发温度为370 K时,系统能量利用率达到最大值.