低温热源喷射式发电制冷复合系统特性分析

提出一种低温热源喷射式发电制冷复合系统。该系统将有机物朗肯循环与喷射式制冷循环相结合，利用透平排气驱动喷射器工作，同时实现发电和制冷的功能。在定义系统评价指标的基础上，选取性能优良的有机物R245fa作为工质，建立系统仿真模型，进行计算分析。计算结果表明，在热源蒸发温度Tg=120℃，制冷蒸发温度Te=7℃，冷凝温度Tc=25℃的标准工况下，系统的热力学第一定律效率可达37%，热力学第一定律折合效率可达15.6%，火用 效率可达37.5%。分析同时表明,提高热源蒸发温度Tg，提高制冷蒸发温度Te，降低冷凝温度Tc，有利于提高系统的工作性能；提高透平膨胀比b可以提高系统电冷比R。

Analysis of a Combined Power and Ejector Refrigeration Cycle for Low Temperature Heat Sources

A combined power and refrigeration cycle is proposed. The proposed cycle combines the organic Rankine cycle and the ejector refrigeration cycle, producing power as well as refrigeration simultaneously. The ejector is driven by the exhausts from the turbine. After the efficiency definition of the combined cycle, a simulation model was established for calculation and analysis. R245fa was chosen as the working fluid for its good performance. At the typical working conditions generating temperature Tg=120℃, evaporating temperature Te=7℃ and condensing temperature Tc=25℃, the first law efficiency of the combined cycle can be 37%, the practical first law efficiency can be 15.6% and the exergy efficiency can be 37.5%. Results show that performance of the cycle can benefit from increasing generating temperature Tg, increasing evaporating temperature Te and decreasing condensing temperature Tc. It is found that larger power/ refrigeration ratio R can be obtained by increasing expansion ratio b.