Design And Analysis Of Parabolic Trough Solar Collector With Lead-bismuth Eutectic

Solar thermal electrical power generation technology,as a clean and renewable green power generation model,is one of the ideal energy sources for the future society.The parabolic trough solar collector is the key component of the parabolic trough solar thermal power system,and its performance is crucial to the efficiency of the whole system.At present,the commercially used traditional parabolic trough solar collector contains single layer glass cover in the vacuum zone,and most of the heat transfer fluid is thermal oil and molten salt.Due to the influence of its structure and heat transfer fluid,the efficiency of solar collector is relatively low under the high working temperature.In this work,the current statutes and the latest progress of development of parabolic trough solar collector was summarized,and,on this basis,a series of beneficial explorations were made on the performance of parabolic trough solar collector,the optimization of the traditional parabolic trough solar collector and the designation of 50 MW parabolic trough solar thermal power plant system operated with lead-bismuth eutectic(LBE).The main conclusions are as follows:(1)In view of the characteristic of non-uniform heat flux on the outer surface of collector,the temperature and flow characteristics of LBE in the collector tube were analyzed.The applicability of the construction of a turbulent Prandtl number(Prt)model in numerical simulation of convection heat transfer of LBE in collector tube was verified by comparing with the empirical formula.The influence of the value of uniform heat flux,inlet mass flow rate and inlet temperature of LBE was analyzed.The validity of the traditional heat transfer formula was verified,and the heat transfer performance of LBE is much higher than that of molten salt.The thermal performance of parabolic trough solar collector with different types of heat transfer fluid was analyzed based on the two-dimensional steady heat transfer theoretical model.Specifically,the direct solar radiation intensity(DNI),outlet temperature,annular vacuum pressure,coating emissivity and ambient state on the performance of collector tube were studied.The results show that liquid sodium shoes the highest efficiency.The biggest difference between sodium,molten salt and thermal oil is 4.24%and 6.03%.The efficiency of solar collector with molten salt,sodium and LBE is 53.2%,59.45%and 60.32%relatively at the temperature of 565 ?.The influence of wind velocity on efficiency is relatively low.(2)A novel parabolic trough solar collector with inner glass shell was proposed to minimize the energy loss of the current commercial collector and improve its heat collect efficiency.The simulation results show that the total heat loss of novel parabolic trough solar collector can be decreased by implementing the inner glass shell,the advantages of novel solar collector in increasing the heat collect efficiency can be further improved by using LBE as heat transfer fluid.The results show that the energy loss of the novel solar collector is less than 7%of the traditional collector.(3)In view of the characteristic of the parabolic trough solar thermal power plant operated with LBE,a 50 MW parabolic trough solar thermal power plant was designed,and the main system parameters were proposed.In addition,the power generation performance of parabolic trough thermal power plant operated with LBE was analyzed compared to with molten salts.The results show that the efficiency of solar thermal power plant with LBE has higher peak efficiency,the annual electrical efficiency is 18.04%which is higher than that of molten salt.