|摘要: ||本研究是利用外徑6mm、內徑3 mm之玻璃管製作9個折彎數總長1980mm之震盪式熱管，為了使震盪式熱管更容易達到循環狀態，故製作水冷系統為冷凝器並控制溫度在35°C，在不同工作流體填充率(20%、30%、40%、50%、60%、70%及80%)、及不同輸入功率(40W、80W、120W、160W、200W)下評估整體熱阻值。
This research utilized 6 mm outer diameter and 3 mm inner diameter glass tubes to manufacture 9 turns closed loop Pulsating Heat Pipe(PHP) with a total length of 1980mm. For achieving the loop circulation easily, a water cooling system kept at 35 ° C was used as the condenser. The experiment was conducted to evaluate the thermal resistance under different fluid filling ratios (20%, 30%, 40%, 50%, 60%, 70% and 80%), and at a series change of heat inputs (40W, 80W, 120W, 160W, 200W).
Through a digital video camera, the visualization experiment was carried out to observe the circulation flow period in the PHP. A styrofoam ball was designed to put into the tube for a better observation and a correct estimation of fluid flow direction. Circulation times and circulation period were observed and calculated from different filling ratio tests. We also analyze the effect of inclination angles to the performance and circulation period in the PHP.
The results showed that PHP reached fully circulation under the filling ratio of 60%, 70%, and 80%, at an input power of 200W. The circulation can be categorized into clockwise circulation, counter-clockwise circulation and transition circulation status. The shorter circulation period happened as filling ratio was 80%. We also found that there were more counter-clockwise circulation occurred in each experiment. Due to gravity effects, better performance and shorter period took place when the inclination angle was 45 °.
Key words: pulsating heat pipes, PHP, circulation flow, circulation period