Study On NLM-TIM Filled Heat Pipe Vacuum Tube Solar Energy Collector

Heat pipe vacuum tube solar collector is the main form of solar energy utilization.Large internal thermal resistance and low heat transfer efficiency are the main problems in the practical application of heat pipe vacuum tube solar collector.The thermal interface material is a kind of thermal conductive material,which can be used to reduce the contact thermal resistance and improve the heat transfer ability between two contact surfaces.In this paper,a new type of heat pipe vacuum tube solar collector filled with nano-liquid metal thermal interface material(nLM-TIM)is presented.The newly developed nLM-TIM is used to optimize the heat transfer inside the heat pipe vacuum tube collector and improve the collector efficiency.The main work of this paper is as follows:(1)A kind of nano-composite thermal conductive material,nLM-TIM,has been developed.In this paper,nLM-TIM is effectively obtained by controlling technology combining ultrasonic dispersion with surfactant regulation.Its maximum thermal conductivity of then nLM-TIM reaches 6.73±0.04 W/(m·K)with filling ratios of 85.7%(v/v)while the volume resistivity is 2.09×10~9?m at 220V,which ensures a high thermal conductivity and electric insulation.(2)The physical model and one-dimensional steady-state heat transfer mathematical model of nLM-TIM filled heat pipe vacuum tube solar collector are established.In this paper,the mathematical and physical model of the collector is established,and the formula of the collector efficiency of the heat pipe vacuum tube solar collector filled with nano-liquid metal thermal interface material is obtained.The theoretical calculation results show that the instantaneous heat collection efficiency of nLM-TIM filled heat pipe vacuum tube solar collector can reach 73%.(3)The performance test platform of nLM-TIM filled heat pipe vacuum tube solar collector was built.In order to verify the theoretical calculation results,a performance test platform of nLM-TIM filled heat pipe vacuum tube collector is built.The experimental results show that the condensation temperature of the heat pipe of the vacuum tube filled with nano-liquid metal thermal interface material in a single heat pipe can reach 150 C,which is36.4%higher than that of the general heat pipe vacuum tube.The experimental results of the instantaneous efficiency of the collector tested on the collector performance test platform are basically consistent with the theoretical calculation values,which further proves that the nLM-TIM filled heat pipe vacuum tube solar collector has excellent collector performance.