Thermal performance assessment of flexible flat heat pipe with various mesh wicks

This study investigates the thermal performance of flexible flat heat pipes with three different wick structures, including the single-layer copper mesh, sintered dual-layer copper mesh, and super-hydrophilic sintered duallayer copper mesh. Performance assessments are conducted across varying working fluid filling volumes in 0.4-0.8 mL and bending configurations in 0-90 degrees. Experiments show that increased filling volume of 0.8 mL markedly achieves an efficient reduction in thermal resistance and an enhancement in maximum heat transfer capacity compared to the baseline 0.4 mL competitor. Although bending angles universally degrade performance, the super-hydrophilic sintered dual-layer copper mesh exhibits superior bending resilience. This advanced configuration sustains 9 W thermal capacity even at the 90 degrees in contrast to 7 W for conventional singlelayer designs. Mechanistic analysis attributes these improvements to the super-hydrophilic surface treatment, which generates instantaneous wettability with 0 degrees contact angle and complete wetting within 1 second, and amplified capillary forces. These synergistic effects counteract bending-induced capillary structure deformation, thereby preserving continuous working fluid reflux. This paper can provide fundamental understanding and testing data in regards to the flexible flat heat pipe.