摘要 本研究利用透明板式熱交換器，以水和空氣為工作流體，模擬冷媒在蒸 發器入口時之狀態，雷諾數範圍從50 到250，利用攝影機拍攝進行可視化， 觀察不同條件下的流動分佈現象，實驗參數包括不同入出口配置、入口大小、 流道和板片間距及擋板在集管內的配置。 實驗結果得知入口集管內部的流譜對流動分佈有明顯的影響，擋集管 上半部的配置可以使液體氣體在集管內混和均勻，使熱交換器的進出口壓 降低於無擋板的配置，整體的流動分佈與無擋板的配置相同。Z 型的入出口 配置相較於U 型有更好的流動分佈，熱交換器進出口壓降U 型則高於Z 型。 板片間距2mm 比板片間距4mm 有更好的流動分佈，因為板片間距2mm 的 集管長度為4mm 的一半，熱交換進出口壓降也較小。不同的入口管徑會改 變集管內的流譜，越小的入口管徑液氣混和區域較長，流動分佈較好，壓降 隨著入口管徑縮小而上升。 關鍵字；板式熱交換器，分佈不均，擋板，可視化。;Abstract In present study, the test section has used a transparent plate heat exchanger to visualize flow distribution. Using water-air flow to simulate refrigerant’s condition at the entrance of evaporator. The range of experiments are from Reynolds number 50 to 250. The experiment has been test with different inlet and outlet (U-type, Z-type) configurations, inlet diameters, and baffle (baffle on top and bottom of header) arrangements. The results shows that the flow pattern in inlet of header has significantly affect the flow distribution in heat exchanger. The header which has the upper baffle arrangement has uniformly mix of air and water. It also reduce the pressure drop compare with no baffle arrangement. The baffle arrangements doesn’t increase the flow distribution in heat exchanger. Z-type outlet configuration shows the better flow distribution than U-type outlet configuration. The higher pressure has found in U-type outlet configuration. 2mm plate spacing show the better flow distribution than 4mm plate spacing, because the header length is longer in 4mm plate spacing. The pressure drop is higher with 4mm plate spacing. The inlet diameter also affect the flow pattern inside of header. Air-water mix region is bigger with small inlet diameter. It’s not only increasing the flow distribution but also pressure drop of heat exchanger. Keywords: Plate heat exchanger, mal-distribution, baffle, visualization.
