Paper Title
Effect of Inner Diameter on the Thermal Performance of Closed Loop Pulsating Heat Pipe

The concept of heat pipes has no longer remained unknown in the thermal management discipline. However a new entrant in the family of heat pipes, known as Closed Loop Pulsating Heat Pipe (CLPHP), has never ceased to be an arena of interest owing to the numerous complexities in its operation. With passing days more and more conclusive studies of the behavior of pulsating heat pipes are emerging, yet its efficient application from engineering viewpoint remains somewhat elusive. Nevertheless these two-phase passive heat transfer devices are deemed to be highly effective in light of their low thermal resistance, compactness, portability, cost-effectiveness and simplicity in constructional design. The present paper attempts to shed some light on diameter as the influential parameter on the thermal performance of closed loop pulsating heat pipe (CLPHP) with inner diameters of 1.5mm, 2.0mm, 2.5mm and 3.5mm. Meandering brass tube of total 6 turns and 0.5mm thickness was taken with ethanol as the working fluid throughout the experiment. The results depict that the CLPHP acts in pulsating mode only up to a definite diameter which is 2.5mm as per the performed experiment. The 3.5 mm pipe acts not as a PHP but as a mere heat pipe only. The thermal performance however increases with increasing diameter and hence the diameter of 2.5mm exhibits good performance. Index Terms- Closed Loop Pulsating Heat Pipe (CLPHP), Inner Diameter, Thermal Performance