Study On Heat Transfer Performance Of CPC Heat Pipe Evacuated Tubular Collector

The global environmental deterioration and energy crisis have been paid more and more attention. Currently, as far as our country is concerned, the low-cost convenient new technology for the renewable energy is needed urgently to meet the demands of various areas. Our country covers a very wide field and owns abundant in solar energy. Thus, solar energy should be largely developed and applied in our daily life. In the application of medium temperature solar energy, it's difficult for the unconcentrating concentrors to reach the higher temperature, and the parabolic trough collector requires a complex tracking system and it costs expensively, therefore, the compound parabolic concentrator (CPC) has a bright prospect of application.The distinguishing feature of CPC heat pipe evacuated tubular collector (CHE) is to combined the vacuum glass technology and heat pipe technology together. Heat pipes possess heat diode characteristics, short heat-up time, excellent heat transfer ability and high isothermal characteristics.The receiver with a vacuum tube can greatly reduce the heat loss caused by surface convection, and hence the heat transfer efficiency can be improved effectively.On the basis of theoretical analysis, according to the analysis of heat transfer performance on solar energy collector, calculation methods were put forward which can determine the overall heat loss coefficient and collector efficiency of finned CHE, unfinned CHE and heat pipe evacuated tubular collector (HE) were put forward. The comparison among thermal efficiency of three kinds of collectors was made. The reliability of the method was verified by testing of the three kinds of collectors. According to the analysis of heat transfer performance on unfinned CHE and HE, it showed that the heat transfer performance of unfinned CHE was the best under high temperature; Comparing the instantaneous thermal efficiency between unfinned CHE and finned CHE, it was found that the heat transfer performance of finned CHE has more superiority; The results of calculation on the heat transfer performance of finned CHE is good agreement with the experimental results.Based on the setup of CHE test platform, both of the heat-up and isothermal...