EXPERIMENTAL INVESTIGATION ON THE CHARACTERISTICS OF A CLOSED LOOP PULSATING HEAT PIPE (CLPHP) FOR DIFFERENT FLUIDS

Abstract

Thermal control is an important topic for thermal management of small electrical and electronic devices. Closed loop pulsating heat pipe (CLPHP) is emerging as the best solution for thermal control. The aim of this experimental study is to search a CLPHP of better thermal performance for cooling different electrical and electronic devices. In this experiment, methanol, ethanol and distilled water have been used as working fluid. The effect of using methanol, ethanol and distilled water as working fluids is studied on thermal performance in different filling ratios. A copper capillary tube has been used having the inner diameter of 2mm, outer diameter of 2.5mm and length of 300mm. The CLPHP has 7 loops where length of the evaporation section is 100mm, adiabatic section is 100mm and condensation section is 100mm. The experiment is done using FR of 28%-88% with 15% of interval varying heat input from 10 watt to 70 watt. The results are compared on the basis of evaporator temperature, condenser temperature and their differences, thermal resistance, heat transfer co-efficient, Nusselt Number, power input and effect of filling ratios. The results demonstrate methanol as the most suitable working fluid at 58% filling ratio. Because, methanol at 58% filling ratio yields the lowest thermal resistance and highest heat transfer coefficient. In case of ethanol and distilled water, optimum filling ratio is found 58% and 88% respectively.