Thermal Analysis of Closed Loop Pulsating Heat Pipe

This study aims to flow visualization and thermal analysis of a closed loop pulsating heat pipe based on inclination angle, charging ratio, type of fluid and heat flux for thermal control of micro electronic equipments. Although a variety of designs are in use, understanding of the fundamental processes and parameters affecting the PHP operation are still vague. A vertical, closed loop, glass PHP with water, methanol and 2-propanol as working fluids is first experimentally investigated for a range of heat inputs, inclination angles and charging ratios. Experimental studies are performed on a PHP, consisting of a heating section, an adiabatic section and a condensation section incorporating heat sink. The capillary tube used in this study has an inside diameter of 2mm and a wall thickness of 3mm.Total length of the pulsating heat pipe is 350cm. The experiments are conducted under forced convection cooling at the condenser section, with heating powers from 10 to 110W, with different heating modes (locations) and charging ratios from 30% to 80%. The experimental results show that the system presented better performance when operating at vertical orientation. Optimal charging ratio is 50% for DI water, 40% for methanol and 40% for 2-propanol. Regarding working fluid the PHP shows better performance when Methanol is used in vertical orientation with the lowest evaporator section temperatures.