Numerical and experimental investigation of common header pulsating heat pipe

Abstract

Pulsating heat pipe is a successful passive two-phase heat transfer device used mainly for cooling such as electronic cooling in spacecraft and other applications. The present work is based on numerical as well as an experimental investigation carried out for a novel design common header pulsating heat pipe (CHPHP) which is different from conventional pulsating heat pipe (PHP). The heat transfer performance of this unique PHP is studied numerically as
well as experimentally. For both approaches, copper CHPHP of 2 mm inner diameter is studied by varying the heat input from 10 w ̶100 W at a filling ratio of 50% for DI-water, ethanol and methanol as the working fluid. CFD modeling is done using ANSYS FLUENT 18.1 (Academic version). A Volume-of-Fluid (VOF) model in conjunction with continuum surface force model is applied considering the two phase flow occuring inside the device. The experimental results validate with the Numerical result and found that the experimental result within the 10% error. The lowest thermal resistance achieved for DI-water is around 1.03 K/W whereas for ethanol it is about 0.1781 K/W and for Methanol is about 0.23 K/W which clarifies that ethanol and methanol proved to be a better working fluid than water. The highest thermal conductivity for DI-water, ethanol and methanol are about 8830.6 W/m-K, 12735.8 W/m-K and 10067.1021 W/m-K respectively which shows the heat transfer efficiency of the CHPHP device. The highest local convective heat transfer coefficient hevap in the evaporator is found for DI-water, ethanol and methanol are about 5972.18.6 W/m2-
K,4543.91W/m2-K and 9632.93 W/m2-K respectively which shows the heat transfer efficiency of the CHPHP device. As the heat transfer performance of a PHP is depend upon the combination of various parameter such as latent heat, surface tension, specific heat and water has the higher value than other two and by comparing all the three fluid ethanol is proved as the best working fluid among all the fluid, methanol also found as better fluid than water for the copper CHPHP.