The Influence Of Non-uniform High Heat Flux On Thermal Stress Of Thermoelectric Power Generator

Solar thermoelectric power generation technology has many advantages over other energy technologies, such as clean and pollution-free, simple structure, no moving parts, and it also has the advantages of compact, highly reliable, and silent in operation. Thermoelectric module is a key part of solar thermoelectric power generation system, and increasing the life span of a thermoelectric generator(TEG) is very important. In order to increase the efficiency of TEG, it is effective to increase the temperature difference between the hot and cold end of TEG. However, bigger temperature difference will result in greater thermal stress and it has negative influence on life span of TEG modules. Meanwhile, in order to get higher heat flux we need to use Fresnel lens to concentrate solar radiation, which will cause non-uniformity of heat flux on the hot end of TEG and will further increase the thermal stress. In this thesis, the influence of non-uniformity of heat flux on thermal stress of TEG has been analyzed.Firstly, an 18-pair TEG model based on real situation was established, numerical simulation results indicated that: the non-uniformity of heat flux imposing upon the hot end has a significant effect on the thermal stress of TEG and life expectation of the device. But when the heating uniformity exceeds 70%, non-uniformity of heat flux has little influence on the maximum thermal stress in the model. Uniform heat flux is favorable for solar energy concentration device design, but it is not a strict requirement.Secondly, the interfaces between the copper strips, ceramic plates and the thermo-pins are the places which are the most possible positions to be damaged by thermal stress. When designing the TEG modules, in order to prolong the life cycle of device, we need to strengthen these positions.Thirdly, for the Gaussion heat flux and Parabolic heat flux distribution, the maximum temperature and thermal stress increase with the decreasing of heating uniformity. Because the uniformities of the above two heat flux distributions change small in the numerical simulation, compared with the uniformity heat flux distribution, the curves of the thermal stress and temperature are greatly influenced by the material parameters of TEG model.