本文以三維CFD軟體配合逆算法及實驗溫度來求得多管板鰭式熱交換器於矩形流道的熱流特性，探討入口風速、鰭片間距及加熱管間的距離之影響。由於空氣流經板鰭管式熱交換器時會產生複雜三維流動，使得鰭片上的熱傳係數非均勻分布，故劃分數個子區域並設定其熱傳係數為常數，使用差分法搭配最小平方法，進行逆向求解，以取得逆算之鰭片熱傳參數；本文利用CFD軟體求得溫度場、流場及熱傳參數，輔以實驗數據與逆算結果對紊流模式及網格劃分進行選用，確保模擬之可信度；結果顯示在自然對流中Zero equation模式所求得結果較為準確，混合對流之結果則顯示風速提升將改變紊流模式選用，在較高速時，Enhanced Realizable k-ε比RNG k-ε紊流模式更符合逆算結果；在本研究參數範圍內，隨風速加快、間距增大及加熱管管距增加會使熱傳係數提升，對應各參數變化之趨勢也會有所不同。

This study uses a hybrid method of computational fluid dynamics (CFD) and inverse heat conduction analysis (IHCA) combined with experimental temperatures to investigate the plate finned tube heat exchangers with two horizontal tubes located in a channel. The effects of parameters such as fin pitch, inlet air velocity and tube location are considered. Since the heat transfer coefficient on the fin is not uniform due to the complex three-dimensional air-flow flows through the plate-fin and tube heat exchanger, the fin is divided into several sub-regions and the heat transfer coefficient in each sub-regions is assumed to be a constant. Later, the inverse method applies finite difference method in conjunction with the least-squares scheme and the experimental data to estimate the heat transfer coefficient on the fins. Furthermore, how to choose the appropriate flow model and the effect of grid points are also investigated. Velocity, temperature and heat transfer coefficient distributions of the fin are determined using the CFD software. More accurate results can be obtained if the heat transfer coefficient is closed to the inverse results and matches the experimental data. The results reveal that the zero-equation turbulence model can be applied to determine more accurate results than other flow models for natural convection. Also, it is found that enhanced realizable k-ε turbulence model is more suitable for higher inlet velocity than RNG k-ε for mixed convection. Finally, with the increase of inlet velocity, fin spacing and distance of tubes, the heat transfer coefficient increases.

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