本研究使用3D數值分析，數值模型為使用橢圓管之差排平滑波浪型熱交換器，主要參數分別為管排數—4、6、8排，鰭片間距—1.2mm、1.8mm、3mm、4mm及差排位置。差排位置為在管排數4、6及8排時，每兩排一組，組間設置差排點，而與實驗數據驗證之j因子之誤差區間為4.4 - 13.9%，f因子之誤差區間為4.3 - 12.6%。結果發現熱傳係數隨鰭片間距減小而上升，不過在鰭片間距為3mm及4mm的樣本中，其熱傳係數相仿。對所有樣本來說，管排數對摩擦因子的影響不大，而摩擦因子隨鰭片間距增加而上升，且雷諾數越高差距越大。在性能指標的表現中，管排數為4的連續型與不連續型鰭片在低雷諾數區時，差異不大，但在雷諾數提高時，不連續型鰭片的性能指標較差。管排數為6之樣本中，差排位置在第4、5排間的樣本其連續與不連續型鰭片在性能指標表現下差異不大，而差排位置在第2、3排間及第2、3排與第4、5排間，此兩種樣本皆是不連續型鰭片的性能指標優於連續型。管排數為8之模型中，只要在管排第2、3排間有差排之樣本，其性能指標皆是不連續型鰭片的性能指標優於連續型。

3D numerical analysis will be employed in this study, and the model is interrupted smooth wavy fin-and-tube heat exchangers with oval tube. The main parameters in this study are the amount of tube rows (4, 6, 8), fin pitches (1.2, 1.8, 3, 4 mm) and interrupted positions. The interrupted positions are set up between groups that one group consists of two rows when the amount of tube rows are 4, 6 and 8. The
verification error area compared to experiment data is 4.4 - 13.9% of j factor and is 4.3 - 12.6% of f factor. It is found that the heat transfer coefficient increase as fin pitch decrease; however, the heat transfer coefficient is similar at F_p=3 and 4mm. For all samples, the effect of tube row on friction factors is negligible. The friction factor increases as fin pitch spacing increase, and as the Reynolds number increases, the increase of friction factor with pitch spacing also accelerates. At low Reynolds region, the performance index is similar between the continuous and interrupted case at N=4; however, the performance index of interrupted case is worse when Reynolds number increases. In the case of N=6, the performance index is similar between the continuous and interrupted case that the interrupted position locates between No.4 &5 tube rows. Moreover, the performance index of the interrupted case is superior to the continuous case at the two cases that the interrupted position locates between No.2&3 tube rows and the other locates between No.2 &3 and No.4 &5 tube rows. In the case of N=8, as long as the interrupted position locating between No.2 &3, the performance index of the interrupted case is superior to the continuous case.

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