使用數值軟體來輔助氣冷式冷凝器的設計已經相當普遍，但當冷媒為非共沸冷媒時，其預測值往往不準確，其中最主要的原因是非共沸冷媒在相變化過程中有溫度的滑移現象及冷凝過程中成份冷媒間的質傳熱阻抗會對熱交換器性能產生影響。
為了能夠更準確地預測非共沸冷媒冷凝器性能，本研究將一冷凝器切割為多個區塊，每個區塊視為單一熱交換器，並利用 –NTU model來模擬。在進行整體飽和區域的熱傳計算時，由於區塊的細分，各個區塊的溫度滑移量減低而可忽略，等該區塊計算完成後再利用設定下游區塊入口條件來加以考量。對於成份冷媒間的質傳阻抗效應，本研究也利用文獻發表的修正式來提高計算精度。
為了驗証此程式之準確性，我們進行各種氣冷式冷凝器的模擬並與文獻實驗數據比較，發現預測誤差值在可接受範圍之內，最後吾人利用此程式評估一使用R-407C冷媒之通用型氣冷式冷凝器性能，此冷凝器之熱交換管為微鰭管而鰭片為波浪型鰭片，並得到優化的鰭片數與空氣表面風速。

It has been a common practice for using a computer code to design an air-cooled condenser. However, the prediction is often too optimistic if the same code developed for pure refrigerants is directly applied for zeotropic refrigerants. This kind of prediction discrepancy is believed caused by the temperature glide and the extra resistance due to the mass transfer during the condensing process of a zeotropic refrigerant.
In this study, the condenser is divided into many blocks. The degree of temperature glide of block in the saturated area will become relatively small for neglect during simulation, and then can be solved by the –NTU method. After each simulation in saturated area, the effect of temperature glide will take into consideration by setting the outlet condition of downstream block. The effect extra thermal resistance due to the mass transfer during condensing process is considered by using the modified correlations published in literatures for zoetropic refrigerants.
We adopted various test datas published in literatures to verify the developed computer program, and the predicted results are generally agreed with experimental data. This program is then applied the design a typical air-cooled condenser. The working fluid of this condenser is R-407C refrigerant flowing in micro-fin tube, and the air-side has a wavy-fins. The optimal outer-fin number per unit length and the frontal velocity of condenser can be obtained by the calculated results using the developed computer code.

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