| In this paper, The theory of finite-time thermodynamics method is used to investigate optimum performance of a new refrigeration system driven by a gas turbine or a combustor. Firstly, the irreversible cycle model of the refrigeration system with the influence of thermal resistance, heat leak and internal irreversibility of the working fluid is established. Based on the irreversible cycle model, the reversible cycle model with heat leak is deduced by neglect of internal irreversibility. And the fundamental optimum relation of the refrigeration system is derived from the point of view of finite investment. Based on the fundamental optimum relation, the optimal performance of the refrigeration system related to the exhaust temperature which is the controls parameter of the system. The relationship between the cooling rate and the coefficient of performance is analyzed. The optimal state of the refrigeration system witch harmonizes the cooling rate and the coefficient of performance, and the work states of a real system is discussed. The variety of the cycle's performance in different high temperature heat source is investigated. Some conclusion witch is significant to real system is established. Finally, the ecological function E is taken as an objective function for further optimization. Some significant discussions are done. The results show that the state of the maximum ecological function is worthwhile to consider in the research and manufacture of real thermodynamic cycles. The results obtained here are quite general. They may be used to discuss the optimal performance of a refrigeration system as long as one chooses suitably the values of the main parameters in the cycle model. And consequently, they provide some new theoretical bases for the optimal design and selection of optimal operating condition of real refrigeration systems. |
