5th International Anatolian Energy Symposium, Trabzon, Turkey, 24 - 25 March 2021, pp.630-636
In this study, influence of the inclination angle on thermal performance and flow characteristics of a flat plate closed-loop pulsating heat pipe is investigated experimentally. The heat pipe has a novel geometry including, larger flow sections in the evaporator region (in the one branch of the relevant U-turns), which also provides a variation of the channel widths in the relevant region. Ethanol is used as the working fluid. Experiments are carried out for different inclination angles (-90°, 0°, 30°, 60° and 90°) and thermal powers (5W – 60W) at a constant filling ratio of 50%. A high-speed camera is used to obtain the images of pulsating flow in the heat pipe. At the positions including positive inclination angles (30º, 60º and 90º), it is observed that thermal resistance significantly reduces with the increasing thermal power. On the other hand, at the top heating mode (-90°) and the horizontal orientation (0°), the thermal resistance showed a horizontal trend with increasing thermal power. The relevant results are also supported by flow visualizations.
Keywords: Pulsating heat pipe, Thermal performance, Flow visualization.