板式熱交換器之入出口壓降實驗分析

板式熱交換器入出口的設計不但會影響到流體進入熱交換器時所產生的壓降，更會對流體在各個流道間的分佈是否均勻有絕對的影響，入出口設計也是決定該型板式熱交換器整體壓降性能是否良好一個重要因素。過去一般文獻入出口壓降多半由Shah and Focke [1988]所提經驗式來估計，但使用在多板片熱交換器上並不適合。本實驗將進行不同管徑入出口內壓降量測，得出較合理的入出口壓降外，並觀察出熱交換器內部流動分佈。實驗數據也將整理出另一合適多板片熱交換器之入出口壓降經驗式。實驗結果顯示影響入出口壓降的因素為流量、入出口管徑，和歧管長度，其中以入出口管徑影響最大。K050、K070和K095由於入出口設計合理，除入出口壓降對總壓降比例低外，分佈不均的情形也不嚴重。K030則因為管徑過小，除了造成入出口壓降過大，產生不必要的壓力損失，同時形成嚴重的分佈不均。

關鍵字

山型紋；壓降；入出口壓降；分佈不均；板式熱交換器

並列摘要

The port and manifolds’ design of plate heat exchangers not only affect the pressure drop but also makes the flow uniform or not in all the channels. How to design the port and manifolds is important because it decides the pressure drop performance of the plate heat exchangers. Reviewed the literature, and we know that almost estimates the port and manifolds pressure drop by Shah and Focke’s correlation in 1988. But the correlation is not reasonable when uses it in a plenty of plates heat exchangers. We can get the correct port and manifolds pressure drop and observe the flow distribution by measuring the pressure drop inside the inlet and outlet ports at different locations for different port dimension. According to the experiment data, looking for a new fit correlation for a plenty of plates heat exchangers. Experiment results show that the pressure drop increase depends on flow rate, port and manifolds length, port and manifolds diameter, and port and manifolds diameter is major. Types of K050, K070, K095 have a good reasonable port and manifolds design. The percents (port and manifolds pressure drop / total pressure drop) is low, and flow maldistribution is not obvious. However type of K030 diameter is small, it makes over large pressure drop. And the port design brings flow maldistribution is serious.