Papers by Author: De Xing Sun

Abstract: This paper introduces rheological property, thermo physical property, flow resistance and heat transfer characteristic of urban original sewage and the calculation thinking and method.

Abstract: The optimal performance of the solar-driven thermodynamics cycle system consisting of a solar collector and a four-temperature-level absorption refrigerator is investigated, based on the linear heat-loss model of a solar collector and the irreversible cycle model of a four-temperature-level absorption refrigerator. A fundamental optimum relation is derived, from which the optimum operating temperature of the solar collector, the maximum overall coefficient of performance and the corresponding coefficient of performance of the four-temperature-level refrigerator are determined. It is proven that the total thermal conductance of the heat exchangers must be divided optimally between the four heat exchangers. The effects of the cycle parameters on the optimum operating temperature of the solar collector and the performance of the system are discussed by detailed numerical examples. The results obtained can describe the optimal performance of solar-driven four-temperature-level refrigerator affected simultaneously by the internal and external irreversibilities.

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.