Abstract
The effect of solid particles on the performance of looped pulsating heat pipe (PHP) has been investigated by using water, ethanol and R141b as working fluids. The PHP is made of copper tubes with 3mm OD and 2mm ID, and the number of turns is 12. Lengths of heating, adiabatic and cooling sections are 50mm, 100mm and 50mm, respectively. In order to improve performance, particles of various size and material, that is, alumina particles (10pm, 0.6pm) and copper particles (20p,m, 10pm, 3pm), were added into working fluids. The PHP was working in bottom, horizontal and top heating mode. In case of water containing alumina particle, it was found that heat transfer performance was enhanced in all orientations. In all cases of R14 lb containing particle, heat transfer performance was also enhanced. However, in case of ethanol containing alumina or copper particle, there was no great difference compared with pure fluid. When base fluid was water, the liquid plug oscillation was enhanced significantly by adding particle in proper concentration. On the other hand, in case of R141b, particle addition had no significant effect on the liquid plug oscillation.
