本研究主要目的為分析不同連接型態(包括串聯、並聯與不同電流比之分離模式)的二級熱電製冷片之冷卻性能。
過去在其他有關於熱電製冷片的研究中，較多學者以固定熱電模組的熱端溫度與冷端溫度為邊界條件，而在本研究裡，取而代之的，我們以控制冷端熱負載為邊界條件，此設定是為了在實際應用時符合電子元件的已知輸入功率。另一方面，以熱電效應的原理為基礎，我們利用數值方法模擬二級熱電製冷片的內部溫度，其內部熱機制不只考慮焦耳效應，同時也將湯木森效應的影響列入考量，此外，為探討湯木森熱對二級熱電製冷片的內部溫度預測及熱傳機制之影響，我們建立三種不同的西貝克係數模型進行分析，包括常數西貝克係數模型(CSM)、二次多項式西貝克係數(PSM)及對數線性西貝克係數模型(LLS)，並透過實驗及模擬檢測此三種模型之準確度及差異性。
主實驗以氣冷系統控制二級熱電模組之熱端溫度，改變輸入製冷片的電流，在不同冷端熱負載下記錄測試模組之冷端溫度及性能係數，以分析不同連接型態下(包括串聯、並聯與不同電流比之分離模式)二級熱電製冷片之冷卻性能，並根據實驗結果決定最佳連接型態。在預實驗中測量不同溫度下熱電製冷片之西貝克係數，將測量數據透過迴歸分析分別求得不同西貝克模型下西貝克係數對溫度的函數，並經由熱電效應關係式求得湯木森係數之函數，分析此三種西貝克係數模型之異同。此外，利用實驗測量的數據於不同西貝克係數模型下進行數值模擬，求出二級熱電製冷片之溫度分佈、冷端溫度及性能係數。最後比較模擬結果及實驗數據，決定最佳西貝克係數模型，並探討其誤差成因及湯木森效應之影響。
根據實驗及模擬結果，由於分離模式下電流比1:2之二級熱電製冷片模組在不同測試條件中具有優秀性能係數及良好冷卻能力，因此在本研究中決定將此模模式選為最佳測試模組(電流比為近冷端製冷片電流與近熱端製冷片電流之比值)。而最佳西貝克係數模型則為考慮湯木森效應之二次多項式模型(PSM)，不僅西貝克係數為一溫度函數，且湯木森係數也為一與溫度相關之性質。於PSM模型下進行數值模擬，分析製冷片內部湯木森熱之分佈，過去多數學者忽略湯木森效應之影響，而本研究中發現在特定電流值範圍中，湯木森熱有助於增進熱電製冷片之冷卻能力，因此未來可能發展利用湯木森效應增進製冷片的性能之技術，其影響潛力不容小覷。

This research “A Study on the Performance of Two-stage Thermoelectric Coolers with Different Types under Thomson Effect” is mainly aimed at the analysis of the cooling performance of two-stage thermoelectric coolers test modules for different arrangements (serial, parallel and separate types for varied current ratios).
In previous investigations of thermoelectric cooler, constant hot and cold side temperatures of thermoelectric module were often chosen as boundary conditions. Instead, in this research we control the heat load of the cold side in order to meet the known allowable power input for the electronic components in practical application. On the other hand, not only Joule heat but also Thomson heat is taken into account in this research. In order to discuss the effect of Thomson heat on temperature prediction and the internal heat transfer mechanism of two-stage thermoelectric coolers, three different Seebeck coefficient models (Constant Seebeck Model, Quadratic Polynomial Seebeck Model and Log-linear Seebeck Model) are examined through experimental investigation and simulation.
With a variety of input current and current ratio, the heat load of the cold side, and the hot side temperature controlled by the blower system, the cold side temperature and the coefficient of performance (COP) of two-stage thermoelectric coolers with different types are obtained through the experiments to study the cooling performance. Seekbeck coefficient is measured by the pre-experiment and its dependence on temperature is developed into three different models by regression. Numerical analysis is then conducted to simulate the temperature distribution inside the two-stage thermoelectric coolers as well as the cold side temperature and the COP. The simulation and the experimental results are then compared and discussed for error analysis and the Thomson effect.
Results show that the separate type with current ratio 1:2 is viewed as the best type of two-stage thermoelectric coolers in this research. This type performs great COP and good cooling capacity under different conditions. Furthermore, we figure out the best Seebeck coefficient model is Quadratic Polynomial Seebeck Model (PSM model), which means Thomson coefficient is also dependent on temperature. In thermal analysis for Thomson heat with PSM model, Thomson heat can enhance the cooling capacity of thermoelectric cooler. This result shows that Thomson heat cannot be neglected in thermoelectric cooler investigation.

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