Effect of Multiple Heat Sources and Bend Angle on the Performance of Sintered Wicked Heat Pipes

Abstract

This study experimentally investigated the performance of a straight heat pipe, with a single heat source (SHS), compared to a heat pipe with multiple heat sources (MHS) of equal total thermal load. Additionally, in order to compare this study to complex electronic cooling solutions, the effect of bend angle and bend location was investigated. The performance of a 400 mm length, 6 mm diameter, cylindrical copper sintered heat pipe was investigated for SHS and MHS cases with bend angles varying from 0°-90°. In addition, the effect of bend location was also studied for the MHS cases. Thermal resistance increased by up to 68% when the setup was changed from a SHS to a MHS. When bend angle was increased, thermal resistance increased by 40-60%. Bend location also affected thermal resistance, causing an increase of between 5-18%. Furthermore, results showed that the optimum bend location for the MHS case was adjacent to the middle evaporator, since the heat load was evenly distributed before and after the bend. A MHS arrangement can disrupt the evaporation-condensation cycle present in a SHS heat pipe. If the combined thermal load was too high, the working fluid in the wick could have evaporated before the final heat source was reached, causing dry out of the heat pipe. This paper concludes that advancements in heat pipe wick manufacturing is desired to account for the increased thermal resistances.