不可逆四热源吸收式制冷机的最优性能

为从热力学角度获得吸收式制冷机更为有用的性能上界,建立其四热源循环模型.该模型将吸收式制冷机视为一个由不可逆卡诺热机驱动的不可逆卡诺制冷机的联合循环系统,考虑热阻及工质内部耗散的不可逆性.运用优化理论,推导出:制冷量与性能系数间的基本优化关系;总热导率在各换热器间的最优分配关系;最大制冷量及相应性能系数的一般表达式.与三热源制冷循环模型相比,四热源制冷循环模型更接近于实际的吸收式制冷机.

Finite-time thermodynamic optimization of an irreversible four-heat-source absorption refrigerator

To obtain a more useful upper bound for the performance of an absorption refrigerator from a thermodynamic angle,a four-heat-source cycle model for this system is presented.In the model,an absorption refrigerator is treated as a combined cycle system of an irreversible Carnot refrigerator driven by an irreversible Carnot heat engine.Using optimization theory,the fundamental optimal relation between the cooling rate and the coefficient of performance,the optimal distribution relations of the total heat conductance between the heat exchangers,and the general expressions of the maximum cooling rate and its corresponding coefficient of performance were derived.As compared with the refrigeration cycle model with three heat sources,the proposed refrigeration cycle model with four heat sources is closer to a real absorption refrigerator.Therefore,the results obtained here are more useful to guide optimal design and performance improvement of a real absorption refrigerator.