噴霧冷卻控制策略於聖誕紅葉面降溫之研究

Abstract

本研究利用超音波振盪造霧器作為噴霧冷卻系統，以間歇性之造霧方式進行噴霧冷卻，探討以不同控制策略（時間、溫度、濕度）進行噴霧冷卻時所形成之環境溫濕度變化，對聖誕紅葉面降溫之影響，並利用紅外線熱影像儀分析葉面溫度分佈之情形。 研究結果顯示，以超音波振盪造霧器作為噴霧冷卻系統，確實可達到良好之降溫效能，並且經由計算得知其蒸發效率約為95％左右。以時間作為控制策略操作噴霧冷卻時，於一次循環完畢後，其環境之乾球溫度比前一次啟動時低，能使環境乾球溫度低7℃，聖誕紅葉溫低6.6℃，同時以熱像儀分析葉面降溫情形，結果以葉緣兩側之部份降溫程度較為一致且效果較好。以乾球溫度及相對濕度作為控制策略操作噴霧冷卻，當噴霧停止條件越接近濕球溫度時，環境乾球溫度及聖誕紅葉溫所能降下之幅度越大。而葉面於降溫及回溫過程，皆產生延遲之現象，其延遲時間約為15秒。若增加設施內之蒸發量，對延遲降溫之現象有所改善；當噴霧時間相同，如縮短其間歇時間，可使回溫時之葉溫峰值降低。

This study using Ultrasonic Piezoelectric Transducer to be the fog cooling system and spraying intermittently for cooling, discusses the Poinsettia''s leaf cooling effect of various control models (Time-delays, Dead zone and humidity control) on temperature and humidity fluctuations, and utilizes infrared themal type detector to measure the temperature distribution of the Poinsettia''s leaf while cooled. The results indicated that the ultrasonic Piezoelectric Transducer have good efficiency of cooling and evaporative efficiency is about 95%. For the time-delays control model, after circulation is finished, the dry ball temperature was lower than last time of fogging, and this can make dry ball temperature have 7℃ and Poinsettia''s leaf have 6.6℃ lower. In the mean time, to measure temperature distribution of the Poinsettia''s leaf by infrared themal type detector while cooled, the part on the both sides of the leaf was better and uniformity. For the Dead zone and humidity control models, the cooling fluctuations of the dry ball temperature and the temperature of the Poinsettia''s leaf can be more as the fog stopping condition approached the wet ball temperature. While the Poinsettia''s leaf was cooling, it were obtained postponed phenomenon, and this postponed time is about 15 seconds; however, the phenomenon of postponement can be improved by increasing the evaporation in facilities. When the fog stopped, shorten interval can reduce temperature of the leaf if time of spraying is the same.