| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 103 === High-temperature industrial waste heat can generally be converted to electrical energy by cogeneration systems. However, low-temperature waste heat (lower than 200 ℃) is difficult to recover, and hence it is usually released into the environment. In recent years, thermoelectric materials associated with the Seebeck effect can be used to convert the low-grade waste heat to high-grade electrical energy without the need of additional generators. Advantages of thermoelectric generators (TEG) include no noise, no vibration, light weight, and workable with certain temperature difference. Therefore, thermoelectric generators are very suitable for low-temperature waste heat recovery. The bottlenecks in thermoelectric power generation technology are low conversion efficiency, reliability of modules, and integration issues of systems and heat exchanger modules.
This experimental work mainly discusses feasibility of integration of a thermoelectric generator with a CPU heatsink module for CPU waste heat recovery and cooling. We use a copper block with heating rods under various heating power for simulating waste heat from the CPU. Five heat pipes are employed to increase the heating area, along with six thermoelectric power generators in series to recover the waste heat generated by the CPU. The electric power generated by the TEG is then used to drive the fan of the cooling module. As the CPU power increases, the temperature of the hot side of the TEG increases, and the temperature difference between the hot and the cold sides becomes larger. The generated electric power and the fan speed increase also. In this way, the fan’s speed can be controlled in accordance with an increase in the CPU power. The whole concept contains environmental protection, green energy, and CPU cooling. For the CPU power of 70W subject to natural convection without loading (that is, without the fan, the heat sink and the TEGs), the steady state CPU temperature rises up to 273 ℃. With the heat sink, the TEGs along with a fan running at full speed, the CPU temperature can be reduced to 76.7 ℃. It can be seen that the cooling effect due to fan and the heat sink module is quite good. Total power of 0.615W is recovered. Moreover, we use the generated electric power of the TEGs to drive the fan. For the CPU power of 70W, 0.727W of energy is recovered. The CPU temperature can arrive at 80.9 ℃. Compared to the fan at full speed, the temperature difference in the CPU is only 4.2 ℃. It indicates that the heat sink module along with the TEGs works satisfactorily in waste heat recovery and CPU cooling. .
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