Investigation of ultra-thin flattened heat pipes with sintered wick structure

This study proposes a novel sintered wick structure called bilateral arch-shaped sintered wick (BASSW) for the improvement of the ultra-thin heat pipes (UTHPs). The bilateral arch-shaped wick was sintered at the middle of its copper container and the vapor flow channels are located on both sides. The sintered wick was manufactured with several paramount parameters including maximum wick thickness, flattened thickness, and copper powder particle size fully controlled. An experimental apparatus was set up to investigate the thermal performance of the UTHP samples under the impacts of incremental heat loads. The effects of each processing parameter on the thermal performance of the UTHP samples were analyzed and compared with a mathematical model incorporating effects of the evaporation and condensation heat transfer in a copper-water wick. Results indicate that the most critical factor for thermal performance of UTHP is flattened thickness, as it decreases, the heat transport capability drastically decreases and the thermal resistance increases. The maximum wick thickness affects the evaporation thermal resistances by the variation of evaporation area of the liquid–vapor interface, and particle size affects the heat transport capability by the variation of the porosity of the wick structure. The thermal resistances of the evaporator and condenser sections are consistent with the mathematical model before dry out occurs. The total thermal resistances of the UTHP samples range from 0.02 K/W to 0.60 K/W, and the maximum heat transport capability can reach as high as 25 W.