Performance Analysis And Heat Dissipation Characteristics Research On Thermoelectric Generator Under High Dynamic Heat Flux

Thermoelectric power generation technology,also known as thermoelectric generator(TEG),is the use of semiconductor materials under the temperature difference formed by the seebeck effect to generate electromotive force,and it can directly convert thermal energy into electricity.Thermoelectric generator devices with its safe,reliable,no noise,the use of waste heat and other advantages have been concerned by the world's scholars,which have a unlimited broad application prospect.However,in the process of using thermoelectric devices,we usually faced with the problem of low efficiency,high thermal stress caused by large heat flux and low heat dissipation rate in the cold end.This article has carried on the corresponding research work to the above question.In the heat transfer-power generation module,we first established a mathematical model for the optimization efficiency of thermoelectric generator.In order to improve the output electrical performance per unit volume(including the output voltage,output power and output efficiency),we proposes a new type of compact temperature generator based on the structural dimensions of the thermoelectric pins.Electrical properties comparation have been made between traditional thermoelectric generator(T-TEG),dimensional optimized thermoelectric generator(DO-TEG)and compact thermoelectric generator(C-TEG)from the perspective of numerical simulation.The results indicatethat C-TEG has an excellent electric performance whose voltage,power,and efficiency decrease slightly whereas the specific output voltage,work,and efficiency compared with that of T-TEG have been significantly improved,with the amplitude increasing with the increase of resistant value of external loads.In the heat transfer-stress module,a mathematical model was established to analyze the heat transfer and thermal stress behavior of a segmented thermoelectric generator(STEG).Temperature gradient-induced thermal stress was studied with non-uniform steady heat flux,uniform heat flux,and transient heat flux applied to the surface of the hot end,respectively.The results showed that the heat fluxes applied to the hot end lead to uneven temperature distribution on the whole surface of the thermoelectric generator.Thermal stress in the horizontal direction is the major cause of fatigue damage and failures of STEG.When the heat concentration ratio increases,the horizontal temperature uneven distribution will also increase.The thermal stress on the hot end varied significantly reaching the maximum value as high as 16.3 GPa.In addition,the transient heat stress in the system gives rise to periodic stress fluctuations up to 0.6 GPa,which can seriously affect the life cycle of the system.Furthermore,in order to solve the problem of cold-side heat dissipation during the actual use of thermoelectric generator,we also studied a microchannel heat sink with impinging jets and dimples structure.Introduction of dimples to heat transfer surface could effectively improve the heat transfer performance of a microchannel heat sink with impinging jets(MIJ).Different forms of dimples,including convex,concave,and mixed dimples are compared to the case without dimple through numerical simulation.The results show that:(1)the cooling performance of MIJ with convex dimples is the best,followed by that without dimple,with mixed dimples and with concave;(2)application of convex dimple could decrease the flow resistance in MIJ;and(3)for overall performance,the convex dimple structure is the best among all tested cases,and the concave dimple the poorest.