三热源吸收式制冷机的传热面积优化

建立了一种可以充分利用低温热源驱动而获得制冷量的三热源制冷机模型,考虑传热及工质内部的摩擦、涡流和其它不可逆性对三热源制冷机循环性能的影响,以总传热面积为优化函数,导出其最小传热面积与三热源熵变化率的关系并得到了热力学第二定律的类比表达式,获得了最佳制冷率与性能系数和传热面的优化关系.分析了工质内部不可逆性对制冷机性能的影响,所得结论可以描述同时受内外不可逆性影响的三热源吸收式制冷机的优化特性,可为吸收式制冷机的优化设计和性能改进提供新的理论途径.

Optimization of heat transfer areas in three-heat-source absorption refrigerator

An irreversible model of three-heat-source absorption refrigerator is set up and driven by low-grade heat energy.The impact of both irreversibilities of heat conduction and irreversibilities resulting from friction, eddy and other irreversible effects inside the working fluid on cyclic performance of a three-heat-source refrig- erator with continuous flow is studied.The total heat-transfer area of the three heat exchangers is taken as an objective function for optimization.The minimum heat-transfer area is described in terms of the rate of the en- tropy changes of the three heat sources,and then an analogue of the second law of thermodynamics is derived. The optimal relation between rate of refrigeration,the coefficient of performance and heat transfer areas is a- chieved.The influence of the internal irreversibilities on the performance of the system is discussed.The re- sults obtained can be used to describe the optimal performance of a three-heat-source absorption refrigerator af- fected simultaneously by the internal and external irreversibilities and can provide some new theoretical ap- proach to the optimization design and performance improvement of real three-heat-source absorption refrigera- tor.