热阻、热漏和内不可逆性对四热源制冷循环性能的影响

在恒温热源内可逆四热源吸收式制冷循环的基础上,考虑环境热源到制冷空间的热漏、工质的内部耗散以及工质与外部热源间的热阻损失,建立不可逆吸收式制冷循环的模型,导出循环的制冷率和制冷系数的基本优化关系、最大制冷系数及相应的制冷率和最大制冷率及相应的制冷系数,给出了最佳换热面积,并通过数值计算分析了循环参数对循环的制冷率、制冷系数的影响.所得结果对实际吸收式制冷机的设计和运行有一定的指导意义.

The Influence of Heat Resistance,Heat Leak and Internal Irreversibility on the Performance of a Four-Heat-Reservoir Absorption Refrigeration Cycle

On the basis of an endoreversible absorption refrigeration cycle, an irreversible four-heat-reservoir cycle model is built by taking account of the heat resistance, heat leak and irreversibilities due to the internal dissipation of the working fluid. The fundamental optimal relation between the coefficient of performance and the cooling load, the maximum coefficient of performance with its corresponding cooling load, and the maximum cooling load with its corresponding coefficient of performance of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the coefficient of performance and the cooling load of the cycle are studied through detailed numerical examples. The results can provide the theoretical bases for the optimal design and operation of a real absorption refrigerator operating at four temperature levels.