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A compact thermoelectric energy harvester is developed to harvest the thermal energy from the hot surface of the gas turbine, providing continuous and reliable power for the sensing and monitoring system in the gas turbine. An experimental prototype is built and the performances of the energy harvester with different electrical load resistances and source temperatures are characterized. A mathematical iterative method, taking account of Thompson Effect, line spacing gap heat leakage, material property variations, and thermal resistance of the ceramic covering layer, is used to analyze the performance of the segmented thermoelectric generator (TEG) module with good accuracy. Based on this model, the temperature profiles and heat fluxes along the thermo-elements, efficiency, and heat leakage through the filling gap material are analyzed. The prototype, with a source temperature of 325 °C, has a voltage output of 2.4 V and power output of 0.92 W, which is more than enough to power a sensor node in the gas turbine. A higher power output can be expected with some improvement on the prototype design. [ABSTRACT FROM AUTHOR]

Thermoelectric generator is a device taking advantage of the temperature difference in thermoelectric material to generate electric power, where the higher the temperature difference of the hot-cold ends, the higher the efficiency will be. However, higher temperature or higher heat flux upon the hot end will cause strong thermal stress which will negatively influence the lifecycle of the thermoelectric module. This phenomenon is very common in industrial applications but seldom has research work been reported. In this paper, numerical analysis on the thermodynamics and thermal stress performance of the thermoelectric module has been performed, considering the variation on the thickness of materials; the influence of high heat flux on thermal efficiency, power output, and thermal stress has been examined. It is found that under high heat flux imposing upon the hot end, the thermal stress is so strong that it has a decisive effect on the life expectation of the device. To improve the module’s working condition, different geometrical configurations are tested and the optimum sizes are achieved. Besides, the side effects on the efficiency, power output, and open circuit voltage output of the thermoelectric module are taken into consideration. [ABSTRACT FROM AUTHOR]

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 (including Gaussian heat flux and parabolic 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. [ABSTRACT FROM AUTHOR]