Various orientations research on thermal performance of novel multi-branch heat pipes with different sintered wicks

The thermal performance in various orientations of gravity was investigated for operating multi-branch heat pipes (MBHPs) with different sintered wicks in the case of cooling a heat source with dual condenser. The effect of sintered particle size in different orientations on heat transfer performance were investigated systematically. The particle size effect was examined with three copper powders of particle size of 50-75 μm, 75-100 μm and 100-125 μm in four orientations of gravity-assisted orientation, anti-gravity orientation, horizontal orientation, and compound orientation of gravity, respectively. All MBHPs were filled by deionized water to the filling ratio of 100%. Experiment results indicate that all MBHPs can operate with similar performance in all the tested orientations before dry-out occurring. Further, the MBHP with 75-100 μm copper powder performs best in all the tested orientations, considering both the thermal resistance and the heat transport capability. In addition, it can start up successfully within 10 min without temperature overshoot and oscillation. That is, a MBHP can perform well in all the tested orientations and the copper powder of 75-100 μm is a good candidate for better thermal performance.