Improving The Performance Of A Thermoelectric Power System Using A Heat Pipe

Low-temperature waste heat recovery technology is recognized as an effective way to increase the energy systems efficiency,slove energy crisis and reduce environmental pollution.However,due to low grade energy and high recovery costs of the low temperature waste heat resources,high recycling efficiency is difficult to achieve.Fortunately,thermoelectric power generation technology provides a solution for this problem.This technology can directly convert thermal energy into electrical energy,the low grade energy can be effectively recycled owing to the advantages of few moving parts,low operating noise,small size,easy use and no pollution.As various low grade heat sources possess different characteristic due to the diffierent forms,how to extract the heat from the low grade heat source into TEGs efficiently should be a key issue affecting the performance of TEGs.Therefore,in order to improve the performance of the TEGs,it is worthwhile to develop a heat transfer device with optimized heat transfer structure to enhance the heat transfer efficiency between low-temperature waste heat resource and TEGs.Heat pipe is a high-performance heat transfer device based on the principles of evaporationcondensation phase-change heat transfer.So it is expected that the heat loss in the waste heat recovery process can be effectively reduced by the combination of heat pipe and thermoelectric power generation.Therefore,a heat pipe thermoelectric power generation experiment platform is designed and constructed,and the influence of temperature uniformity on the thermoelectric power generation is studied in this paper.Furthermore,a large thermoelectric power generation system based on a tridimensional gravitational flat heat pipe is build and tested.The result and conclusions are summarized as follows:(1)An experimental test for the thermoelectric power generation system is conducted to study the influences of the heat spreader on the temperature uniformity.A gravitational flat-plate heat pipe is designed and fabricated as a heat spreader to diffuse the local heat source of the TEGs.The effects of the heating power,inclination angle,and local heat source size on the power generation performance of the TEGs using a flat-plate heat pipe as a heat spreader are examined and compared with that using a copper plate.Besides,the influence of temperature uniformity on the performance of thermoelectric power generation system is analyzed theoretically.The results indicate that the temperature distributation of the gravitational flat-plate heat pipe is more uniform than the copper plate.The superiority of temperature uniformity in the improvement of power generation performance for the thermoelectric power system using heat pipe is demonstrated.In addition,the heat pipe still shows good adaptability when heated under different incline angle and to local heat source size,which is beneficial for the application in the thermoelectric power generation.(2)An experimental study is conducted on the performance of a large thermoelectric power generation system based on a tridimensional gravitational flat heat pipe.Several commercial TEGs have been compared to pick up one of the best performance.According to the maximum operating temperature of the TEGs' hot side,a three-dimensional stainless steel flat heat pipe with decane being the working fluid is designed.Only when the performance of the heat pipe meets the requirements,can the Thermoelectric power generation experiment be conducted.The result shows that when the liquid filling rate of the tridimensional flat heat pipe is 31.7%,the heat pipe can start quickly and maintain good temperature uniformity performance form startup till steady state when heated by the heat sourse.Besides,the average temperature of the six sides of the heat pipe is also very close.When the temperature difference between the hot and cold sides of the TEGs is 148°C,487.4W electricity power is generate by the system and the efficiency is 3.99%.In addition,as the heat load increases,the temperature uniformity of the heat pipe gradually increases,which results in the increase of the thermoelectric power generation efficiency.