| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 104 === In recent years, the problem of shortage of energy is growing up, therefore, waste heat recovery have become a very important issue. And the thermoelectric material plays an important role in this issue. A geothermal plant, since the heat is lost in the pipeline, we can use the thermoelectric material to recover the waste heat, and utilize dissipated heat as a stable heat source.
The aim of this study is to simulate the situation of the waste heat recovery with the geothermal module. In this thesis, the experiment and simulation are discussed. In the experiment, we investigate the case of waste heat recovery with single thermoelectric generator, followed by the geothermal module. In the simulation, we simulated the single thermoelectric generator by the Thermoelectric module in the Ansys Workbench, followed by the geothermal module which was simulated by the Fluent and the Thermoelectric module in the Ansys Workbench. Finally, we compared and discussed the experimental and simulated data.
The result shows that the thermoelectric generator TEG616-6 provided by ITRI is a high-performance thermoelectric generator,. The open circuit voltage, output power, and the internal resistance of the thermoelectric generator all increase with the elevating temperature of the high-temperature side,. When the high-temperature side was at 200℃,and the low temperature side was at 30℃, the output power can reach 5.42W, the power density was 3387.5W⁄m^2 , and the efficiency was about 5%. In terms of geothermal module, when the hot water side was at 90 ℃, and the cold water side was at 25℃, the output power can reach 2.6529W, and the power density was 414.515W⁄m^2 ,. In the simulation of the single thermoelectric generator, according to the verification process,the electrical resistivity can be predict by the first order regression analysis with intermetallic layer modification,. The seebeck coefficient and thermal conductivity can be predict by the secondary order regression analysis. In the simulation of the geothermal module, we utilized the turbulence model and the steady energy model to approach the practical situation. After comparing the experimental data with the simulated data, it shows the error is very small. In the end of the thesis, we can predict the performance of the geothermal module with the hot water temperature exceeding 100℃,. The simulation result shows that when the hot water side was at 100℃, 125℃, 150℃, 175℃ and 200℃as well as the cold water side was at 25℃, the maximum output power can reach 3.68W,5.55W, 8.68W, 13.92W and 18.66W.
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