A Pulsating Heat Pipe (PHP) is a wickless meandering capillary tube bent back and forth parallel to itself. In the present work, the possibility of employing a multiturn PHP as a pin-finned heat sink attached to a base plate is considered. Hence all the regions, other than those belonging to evaporators, function as condenser zones. Experimental investigations are carried on PHPs with multiturn, single plane and multiplane configurations. The condenser (or fin portions) of the PHPs is cooled by forced air flow and radiation to the surroundings. Experimental parametric runs are conducted by varying the fill ratio, orientations, and heat loads. Working fluid namely methanol is tested. PHP with 18 turns are tested for fill ratios of 30%, 50% and 70% and five orientations (+ 90°, + 45°, 0°, - 45° and - 90° measured with respect to horizontal). Heat loads are increased in steps of 50 W from 50 to 400 W for testing the PHPs. For different PHP physical geometries, the flow regimes change with respect to heat loads. The optimum angle for best thermal resistance is found to lie between 60 and 70°. Orientation independent operation observed in all the multiplane models and generally, the bottom heating mode (+ 90°) produce the highest heat transfer. During the startup, for lower heat loads, a temperature overshoot is observed before the establishment of pulsations. At higher heat loads, pulsations are set up without appreciable temperature overshoot, following a smooth startup. The results have shown enhancement in fin thermal conductivity compared to solid copper. The average thermal resistances Formula: see text for 18 multiplane is 0.3408 compare to dry fin thermal resistance Formula: see text Formula: see text shows its improvement in performance.
Babu et al. (Sat,) studied this question.