旁通概念應用在鰭管式熱交換器結露時之性能探討

Abstract

為改善熱交換器的性能，本研究將旁通(partial bypass)概念導入傳統氣冷式鰭管熱交換器之設計，使得部分氣流流經熱交換器時不會流經前排熱交換器而直接流往後排熱交換器。儘管減少通過前排熱交換器的氣流量將降低前排熱交換器的熱傳性能，然而後排熱交換器的熱傳性能也將獲得提升。在此一消一長之情況下，其總熱傳性能可能不變或小幅度降低，然其總壓降將明顯降低。為評估此性能，本研究藉由實驗的設計，分析傳統氣冷鰭管式熱交換器與含旁通設計之熱交換器之間性能的差異。比較在不同幾何參數與熱負載下之熱傳現象與壓降，做為新一代兩排/多排含旁通之熱交換器設計之參考。

This research is for improving the performance of fin-and-tube heat exchangers with the concept of “Partial bypass”. The basic idea of “Partial bypass” is to introduce bypass stream which bypasses the front part to the rear part of the heat exchanger via reducing the contact area of the front part of the heat exchanger. Reducing the contact area of the front part of the heat exchanger will lower the heat transfer performance; however, the heat transfer performance of the rear part is substantially increased. The concept can be implemented with maintaining the heat transfer rate but accompanies with a much lower pressure drop, or it can be applied with the same pumping power but accompanies with a much higher heat transfer rate. By changing the contact area and the type of the heat exchanger to change partial bypass condition, we can observe the impact on the performance of heat transfer and pressure drop under different partial bypass circumstances.