The Thermodynamic Analysis And Optimization Research Of The Solar Energy And Direct-fired Machine Combined Refrigeration System

Currently, the direct-fired machine is one of the application forms in our building heating and cooling systems, which is used widely, especially in the cities. Solar energy is renewable energy and it is distributed widely and has great potential in applications. Although solar absorption refrigeration technology is received more attention, it 's not much practical application because of existing research issues of the connection form and equipment matching, especially the combination of solar energy and direct-fired machine.This thesis aims to study the solar energy and direct fired machine combined refrigeration system. Building and simulating the model of the solar system with a direct-fired combined, then, analyzing the main factors that affect the efficiency of the system, by taking advantage of the TRNSYS and eQUEST, which are hourly energy simulation software,based on relying mainly on thermodynamic analysis while heat transfer and economic analysis subsidiary. At last, it is obtained that the optimum operating combination conditions of the solar energy and direct fired machine combined refrigeration system in a typical hot summer and cold winter area( in Changsha), through the univariate sensitivity analysis of the main factors and the orthogonal experiment design, then, it provides a reference value for the building energy designers, equipment manufacturers and consumers.First of all, lots of related references are consulted and the forms of the solar energy and direct-fired machine combined system are studied and the major components and the connection operation mode of the system are identified ultimately. On this basis, through the thermodynamic theory analysis of the systems energy, the main factors are obtained, which effects the efficiency of the system.Secondly, the model of the solar energy and direct fired machine combined system is built and the system is simulated and analyzed by the TRNSYS and eQUEST.the degree of influence and sensitivity of three factors affecting on the system efficiency are calculated by the single factor sensitivity analysis.Finally, the orthogonal experiment scheme is designed and the system is simulated 25 times according to the number of factors and values, whose purpose is to use the minimum number of trials to obtain the reasonable test data and optimize the system ultimately.It is a feature that the system model is built by using TRNSYS and eQUEST and the optimum operating combination conditions is obtained by the more accurately simulation and optimization in the typical hot summer and cold winter area(Changsha area, outdoor dry bulb temperature is 35.8 ?, wet bulb temperature is 27.7 ?, relative humidity is 75%), in other words, it is the best operating combination conditions of the system when the heat source temperature is 85 ?, the cooling water temperature is 30 and the chilled water temperature ?is 13 ?. To some extent, these datas plays a guiding role to the operations optimization of using solar cooling system combined with the direct-fired in the place and the similar area.