PERFORMANCE OF A GRAVITY INDEPENDENT HEAT PIPE

Heat pipes are two phase cooling devices which provide one dimensional heat flow. Passive transport of working fluid continually in heat pipes is enhanced by wicks, which exploit wicking through capillary action. In the present study, an empty pipe, a thermosiphon, an unsintered wick and a sintered wick heat pipe, were considered for comparison. The thermal behavior, total thermal resistance and heat transfer coefficient of these pipes were investigated at 5W, 10W, 15W, 25W, 35W and 50W. The thermosiphon performed better than the empty pipe due to the introduction of working fluid exchanging heat by phase change. The presence of a wick structure proved to further increase the thermal performance of the heat pipe. Sintering reduced pore spaces and increased the wicking ability and hence the thermal performance. Wicks were manufactured from 140 μm average diameter copper powder. Results show that temperatures at the evaporator section for the un-sintered and sintered wick heat pipe were identical. The performance of the un-sintered and the sintered wick heat pipe were also investigated in against-gravity conditions. The results portrayed that their evaporator temperatures were alike. However, the un-sintered wick heat pipe performed better than the sintered wick heat pipe.