Papers by Keyword: Optimal Relation

Abstract: In this paper, a generalized irreversible heat pump driven by steam turbine cycle model was established by taking account of the heat resistances, heat leak and irreversibility due to the internal dissipation of the working substance. The heat transfer between the heat reservoir and the working substance is assumed to obey the linear (Newtonian) heat transfer law, and the overall heat transfer surface area of the assumed to be constant. The fundamental optimal relations between the heat load, the thermal coefficient of the system and the temperature difference of the evaporator are obtained. Moreover, the effects of the cycle parameters on the characteristics of the cycle are studied by numerical example. The results obtained herein have realistic significance and may provide some theoretical guidance for the performance improvements and optimizations of heat pumps driven by steam turbine.

Abstract: The optimal performance of an absorption refrigerator operating between four temperature levels with the losses of heat resistance and internal irreversibility is analyzed first by taking the total heat transfer area of heat exchangers as an objective function. The minimum total heat transfer area is described in terms of the rate of the entropy changes of four heat reservoirs, and the generally optimal relation among the cooling load, the coefficient of performance and total heat transfer area is achieved. Then, an ecological optimization criterion is proposed for the best mode of operation of the absorption refrigerator. We investigate the ecological optimization performance and derive the corresponding cooling load, coefficient of performance and entropy production rate at the maximum ecological criterion for the absorption refrigerator. A comparison of an absorption refrigerator performance under maximum ecological function and maximum cooling load conditions is presented. Effects of the cycle parameters on the ecological performance have been discussed.