- 學位論文
蒸發冷凝式冰水機之灑水效率研究
A study of water spraying efficiency in evaporative cooling chiller
摘要
本研究主旨在探討蒸發冷凝式灑水效率之均勻度分析，以50個集水器測試水滴分佈，並利用可視化之實驗，觀察噴頭噴灑液滴現象，實驗在流量135LPM和176.4LPM，噴頭間距15公分與17公分，三種噴頭（1號噴頭開口長度和寬度分別為4公分和0.7公分，2號噴頭開口長度和寬度分別為4公分和1公分，3號噴頭開口長度和寬度分別為3.5公分和0.8公分），集水容器和噴頭高度差為16~32公分；測試在噴頭灑水時上述各參數對均勻度之影響。實驗結果顯示，於蒸發冷凝式冰水機灑水效率中，其噴頭開口之截面積設計與流量變化對於均勻度的影響非常大，若能有效控制噴嘴出口流速於1.2m/s左右，可減少液滴流失及增加撞擊飛濺情形，本研究透過改變流量之測試而歸納出較佳均勻度之流速。由改變噴頭開口截面積觀察噴灑現象，發現在高流量時，2號噴頭盛接量和均勻度都優於1號噴頭；在低流量時，1號噴頭在間距17公分較佳，而在間距15公分時2號噴頭較佳，原因為距離拉近，2號噴頭開口上下寬度較1號噴頭大，導致相鄰噴頭噴灑出液滴撞擊點較近，撞擊後液滴飛濺情形也發生較明顯。
並列摘要
This study aims to investigate the water spray uniformity of sprinkler in an evaporative condenser. Experiments of water droplet distribution are conducted with 50 water collectors, and the nozzle spray droplets patterns were observed during the tests. Three different combinations of nozzle opening length and width (4 cm x 0.7 cm, 4cm x 1 cm, and 3.5 cm x 0.8 cm) were tested with the flow rates varied at 135 LPM and 176.4 LPM. The nozzle spacing were either 15 cm or 17cm, and the distance between water collector and nozzle ranged from 16 cm to 32 cm. Experimental results show that the cross-sectional area of nozzle opening and flow rate significantly affect the water spray uniformity. If the water flow speed can be effectively controlled, this will help to shorten the impact distance, which improves spattering phenomenon and increases the ratio of collected fluid. In this study, at high flow rate, the nozzle opening with 4 cm in length and 1 cm in width transports/channels provides better water spray uniformity compared to the nozzle opening with 4 cm in length and 0.7 cm in width. On the other hand, at low flow rate, the nozzle opening with 4 cm in length and 0.7 cm in width provides better impacting effect with the nozzle spacing of 17 cm, yet the nozzle opening with 4 cm in length and 1 cm in width performs better with the nozzle spacing of 15 cm. The latter case, with the smaller nozzle spacing and bigger nozzle opening size, leads to a shorter impact distance of the spraying flow from two adjacent nozzles﹐and subsequently the spattering of water droplets is more pronounced.