近年來熱電技術很有發展前景。熱電發電器（thermoelectric generator）是一種可以回收廢熱並將廢熱轉化為電能的裝置。熱電發電器是個可以廣泛用於許多產業的綠色能源。本研究對熱電發電器系統的研究，分為兩部分。第一部分為開發先進的熱電模擬技術，此技術整合了計算流體動力學（computational fluid dynamics）和熱電模組（TEM）;第二部分是對溫度依賴性的材料進行熱電發電器性能的分析。
在第一部分的研究中，開發一種先進的模擬技術，本研究成功整合計算流體動力學和熱電模組，其中熱電模組被視為一個吸熱源以吸收煙氣中的廢熱。為了模擬從煙氣中收集廢熱的熱電發電器的實際性能，本研究評估了雷諾數、冷面對流係數、煙氣的入口溫度、兩個熱電模組以及煙道之幾何形狀對熱電模組的影響。其結果顯示當雷諾數、煙氣入口溫度與冷面的對流係數上升時，將提高熱電模組的性能。在兩個熱電模組系統中，位於上游的熱電模組的性能非常接近於單個熱電模組。與單個熱電模組相比，兩個熱電模組可以提升43％的輸出功率。然而，這也意味著位於下游的熱電模組的輸出功率與位於上游的熱電模組相比下降了57％，這是因為上游熱電模組對下游熱電模組的影響。當修改煙道幾何形狀以提高雷諾數達到1,000的煙氣速度時，輸出功率和效率能達到53.51％和25.2％的提升。
第二部分的目的是針對四種不同的熱電發電器材料提供一個完整的分析，其材料性質具有恆定和溫度依賴的特性。通過數值模擬並分析了各元件之間溫差、冷面溫度以及熱面溫度振盪對發電機性能的影響。結果顯示，可變性質材料的輸出功率、溫差平方規則以及阻抗匹配的結果皆偏離了具有恆定性質的結果，但其結果依然擁有自身一致性。在給定的溫差下，冷面溫度的降低可能會增強或降低其性能，這取決於所採用的材料特性。振盪熱面溫度可以增加或減少輸出功率和效率。總之，熱電發電器的實際性能及其與理論性能的偏差很大程度上取決於所採用的材料性質。因此，與具有恆定性質的預測相比，考慮可變性質可以提供更真實的結果。

The thermoelectric technology has the prospect in recent years. Thermoelectric generator (TEG) is a device that can recover waste heat and convert waste heat into electricity. TEGs can be extensively employed for green power generation in many industries. This study of a thermoelectric generator system is divided into two parts. The first part develops an advance simulation technology which integrates computational fluid dynamics (CFD) and a thermoelectric module (TEM); the second part is a comprehensive analysis on the performance of thermoelectric generators with different material properties.
In the first part, an advanced simulation technology, integrating computational fluid dynamics (CFD) and a thermoelectric module (TEM), is developed where the TEM is modeled as a heat sink to absorb waste heat from flue gases. To approach the realistic performance of thermoelectric generators harvesting waste heat from flue gas, the influences of Reynolds number, convection heat transfer coefficient at the cold surface, flue gas inlet temperature, dual TEM, and channel geometry on the performance of the TEM system are evaluated. The results clearly provide a measure in increasing the performance of TEM with rising the Reynolds number, flue gas inlet temperature, and convection heat transfer coefficient at the cold surface. In the dual TEM system, the performance of the leading TEM is very close to that of the single TEM, and the dual TEM can produce an additional 43% power when compared with the single TEM. However, this also implies that the output power of the trailing TEM drops 57% when compared to the leading one, stemming for its impact upon the downstream TEM. When the channel geometry is modified to raise the flue gas velocity at Re=1,000, the output power and efficiency with 53.51% and 25.2% improvements are achieved.
The purpose of second part is to provide a comprehensive study on power generation of thermoelectric generators using four different materials with constant and temperature-dependent properties. The influences of the temperature difference across the elements, the temperature at the cold side surface, and the temperature oscillation at the hot side surface on the performance of the generators are simulated numerically and analyzed systematically. The predictions indicate that the output power, temperature-difference square rule, and impedance matching of the materials with the variable properties deviate from the theoretical results with constant properties, but their behavior always obeys the self-consistency. At a given temperature difference, a decrease in the cold surface temperature may intensify or abate the performance, depending on the material properties adopted. Oscillating the hot surface temperature may increase or decrease the output power and efficiency. In summary, the practical performance of a thermoelectric generator and its deviation from the theoretical performance depend strongly on the properties adopted. Therefore, the consideration of the variable properties of material can provide a more realistic outcome compared to the predictions with constant properties.

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