两级吸收式制冷机的优化分析

建立一种不可逆的两级吸收式制冷机模型,考虑有限速率传热和工质内部不可逆性对制冷机性能的影响.以总热导率为优化目标函数,获得最小总导热率与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,导出最佳制冷率、性能系数和总热导率之间的优化关系,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两级吸收式制冷机的优化特性,可为两级吸收式制冷机的优化设计和性能改进提供新的理论途径.

The optimum performance characteristics of a two-stage absorption refrigerator

An irreversible cycle model of a two-stage absorption refrigerator is set up and used to analyze the performance of the refrigerator affected by the irreversibility of finite-rate heat transfer and the internal irreversibility of the working material.The total thermal conductance of the six heat exchangers is taken as an objective for optimization.The minimum total thermal conductance is described in terms of the rate of the entropy changes of the six heat reservoirs,and then an analogue of the second law of thermodynamics is derived.The optimal relation among the rate of cooling load,the coefficient of performance and the total thermal conductance is achieved.The influence of the internal irreversibility on the performance of the system is discussed.The results obtained can describe the optimal performance of a two-stage absorption refrigerator affected simultaneously by the internal and external irreversibilities and can provide some new theoretical approach of the optimization design and performance improvement of real two-stage absorption refrigerator.