Analysis of 360 degree coiled turns in CLPHP

Closed loop pulsating heat pipes (CLPHPs) are a promising device in the thermal management field. The performance of CLPHPs is dependent on a number of parameters including: internal diameter, geometry, number of turns, working fluid, and inclination angle. This paper explains the experimental analysis of the performance of a CLPHP with some parametric variations. The experiment provides knowledge of the effects of these parametric changes on the design, fabrication and performance of the CLPHP. The CLPHPs examined in this project were constructed using 0.065 in copper tubing. The first CLPHP was designed around a standard ten turn CLPHP, where each turn was 180°. The second CLPHP was altered so that every turn was a 360° coiled turn. This was done to investigate the effect of this geometric alteration of the CLPHP\u27s performance. This 360° coiled turn added more surface area, working fluid and height to each turn. This project was done to determine whether these changes would result in additional heat transfer through the device. To determine the performance of each CLPHP a number of tests were done from which certain characteristics of the performance were analyzed. Each CLPHP was tested at the vertical or 90° orientation as well as, 60°, 30° and while horizontal (0°). The heat transfer from each experiment was determined from the change in temperature across the condenser section. The thermal resistance and time taken for each experiment to initiate the oscillating performance were recorded as well. The experiments conducted in this project showed that the 360° turn design performed better at lower orientations than the standard 180° design. At the 60°orientation the 180° design produced 52.25 W and the 360° design produced 63.21 watts. At the 30° orientation the 360° again maintained a higher heat transfer. The 180° design produced 30.66 watts and the 360° design produced 42.61 watts. At both the 60° and 30° orientations the 360° design produced a lower thermal resistance of 1.89 Co/W and 2.37 Co/W respectively. For the same orientation the 180° design produced 2.22 Co/W and 3.39 Co/W respectively