|摘要: ||本研究主要目的為不使用任何閥件下，開發一即可自行向下傳熱之迴路，實驗裝置使用外徑6 mm，厚度2 mm之不鏽鋼管作為冷凝蓄壓槽與管路之材料，蒸發器與熱交換器則使用銅管製作，工作流體為充填率固定85 %之去離子水，加熱功率為30 W、50 W與70 W，並分別使用五種冷卻水溫(15 °C, 20 °C, 25 °C, 30 °C, 35 °C)。實驗改變兩種不同的蓄壓槽入口端高度與冷卻水溫度，探討在不同加熱功率下迴路之熱傳性能。|
當蓄壓槽入口端高度較低時，槽內無足夠的空間給予蓄壓，導致流體回流致使迴路無法作動。則入口端高度較高時，蒸發端所產生之蒸汽可有效地傳至蓄壓槽內蓄壓，當蒸汽壓力足夠後，則可藉由壓力與重力作用使得管內液體回流至蒸發器，使迴路達成向下傳熱與循環作動。此外，當冷卻水溫度為25 °C與20 °C時，迴路有較佳的循環作動，加熱功率為70 W與冷卻水溫為30 °C時，可得迴路之最低熱阻為0.31 °C/W。
The main objective of this research was to develop a valve-less self-acting reverse thermosyphon loops (RTL) that transmits heat downwards with a modified inlet height of condenser reservoir. The condenser reservoir and vessels of this experiment were made of stainless steel with outer diameter and thickness of 6 mm and 2 mm respectively while the evaporator and heat exchanger were made of copper. The working fluid used was distilled water with a fixed filling ratio of 85%. Various heat inputs (30W, 50W, 70W) and temperatures of cooling water (15°C, 20°C, 25°C, 30°C, 35°C) were used. The loop heat transfer performance was determined by using various heat inputs and cooling water temperatures.
When the inlet height of condenser reservoir was lower, the cyclical motion can’t take place as the accumulated pressure in the condenser reservoir is too low for putting working fluid into motion. However, when the inlet height of condenser reservoir is higher, the vapor from evaporator can be transmitted efficiently to the condenser reservoir. Thus, the fluid inside the vessels can flow back into evaporator with the assistance of pressure difference and gravitational force as the accumulated pressure was higher and sufficient. Hence, a downward heat transfer and cyclical motion can be achieved in the loop. Besides, a better cyclical motion was obtained when cooling water temperatures were at 25°C and 20°C whereas the lowest resistance which was 0.31°C/W happened at heat input of 70 W and cooling water temperature of 30 °C.