在工程領域的熱傳問題中，常用傳統的正算法來求解物理量。正算是指給定輸入條件，例如熱對流或熱傳導機制，從而獲得確定的輸出結果，這類問題被稱為正算問題（Direct Problem）。因為我們可以利用已知的物理法則和條件，通過一系列的計算來得到想要的結果。然而，在實際的工程問題中，存在許多物理量是無法直接測量或計算的。這些物理量往往因為設備的限制或環境的複雜性而難以直接獲得。因此，為了獲得這些無法直接測量的物理量，我們必須利用反算法。反算法是根據其他已知的參數或測量資料來反向推算未知的物理量，這就是所謂的反算問題（Inverse Problem）。反算問題的解決對於系統的性能優化和故障診斷具有重要意義。
本論文可以分為兩個章節，均探討暫態熱傳導與熱對流共軛之反算問題於未知暫態熱通量之預測。在探討未知暫態熱通量相關的反算問題時皆以商業軟體CFD-ACE+來建立物體幾何模型與網格，再使用共軛梯度法(Conjugate Gradient Method)藉由已知的邊界條件，配合模擬或真實之溫度感測器測量物體表面溫度來預測未知暫態熱通量。
第二章中，我們考慮了一個在底部有未知暫態熱通量的平板，並研究了該平板模型在不同風速、板厚與時間的條件下對未知暫態熱通量預測的影響。結果顯示，當使用平板且不考慮量測誤差時，我們可以準確預測出熱通量，而入口速度並不會對預測結果造成影響。隨後，我們加入量測誤差來觀察其對反算結果的影響。最終的結論是，由於反算問題是不適定的，所以在厚度較大的情況下，底部熱通量對表面溫度的影響變小，即使我們能準確預測表面溫度，但仍然難以精確預測底部的熱通量。
第三章為實驗部分，旨在驗證第二章數值模擬的可靠性。並且考慮到實際工程的應用我們設計了散熱器模型，使用紅外線熱像儀測量散熱器表面溫度，並利用熱像儀分析軟體TAS20和Python內插方法獲取所需的溫度分佈。接著，我們運用共軛梯度法(Conjugate Gradient Method)結合CFD-ACE+商業軟體，根據散熱器間空隙的表面溫度來預測散熱器底部面的未知暫態熱通量。

An inverse conjugate heat transfer problem is examined to estimate the temporally and spatially dependent unknown surface heat flux using thermography techniques via a thermal camera in a three-dimensional domain. In the present study the interface conditions of plate and air domains are obtained using perfect thermal contact condition, therefore it is defined as inverse conjugate heat transfer problem. The conjugate gradient method (CGM) is chosen as the optimization algorithm for this inverse problem and the advantage of CGM lies in its ability to handle problems without prior knowledge of the functional form of the unknown functions. This allows for the correction and estimation of a large number of unknowns in each iteration, consistently yielding accurate estimates.
This thesis can be divided into two chapters, both discussing the inverse problems of transient heat conduction and heat convection for predicting unknown transient heat flux. In exploring inverse problems related to unknown transient heat flux, the commercial software CFD-ACE+ is used to establish the geometry and mesh of the object. The Conjugate Gradient Method (CGM) is then applied to predict the unknown transient heat flux using known boundary conditions based on the simulated or real temperature measurements on the object's surface.

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