In low-temperature difference, a closed-loop pulsating heat pipe (CLPHP) can be used as a cooling device due to its capability to transfer heat. The thermal performance of the CLPHP is affected by the working fluids. In this work, the effects of some operating parameters such as using ethanol as working fluid with 0.5 filling ratio, orientation, and power inputs are offered based on experimental study. Where the CLPHP was constructed and tested to achieve a better vision into the effect of orientation of 0°, 15°, 30°, 45°, and 90°, and power input of 50 W, 115 W, 215 W, and 450 W on the heat transfer characteristics and the thermal performance. The results indicated that the minimum thermal resistance can be reached at 0.1585 (℃/W) with an orientation of 90° and a power input of 450 W. The results revealed that the inclination angles and power inputs had considerable influence on the enhancement of the thermal performance of the CLPHP. For the low boiling temperature of the working fluid, the power input is more favorable because of fast startup compared with a high power input that leads to some difficulties like the dry-out phenomenon.
Experimental characterization of an n-pentane oscillating heat pipe for waste heat recovery in ventilation systems