Enhancing the resilience of screen mesh wick heat pipes to the degenerative effects of bending-induced deformation

An experimental study has been carried out to investigate the feasibility of enhancing the resilience of screen mesh wick heat pipes to the degenerative effects of bending-induced deformation. This was achieved by orienting the cross-members of the screen mesh on a bias to the heat pipe’s longitudinal axis. Six copper–water heat pipes with single-layer screen mesh wicks were fabricated and characterized for this purpose. The effects of screen mesh number and bias angle were considered. The results were compared to a thermo-fluidic model to verify the nominal performance of each heat pipe prior to bending. Furthermore, post-test Micro-CT imaging was carried out in order to examine geometrical changes to the screen mesh wick structures within the deformed region. The findings indicate that bending has no effect on the axial temperature drop, and hence the thermal resistance of the heat pipes prior to the onset of dry-out. However, bending significantly reduced (by up to 26.1 %) the heat transfer limit of the orthogonal (i.e., non-biased) screen mesh wick heat pipes. Heat pipes featuring higher screen mesh numbers (i.e., finer meshes) exhibited a lower resilience to bending (∼12 % larger drop in heat transfer limit). Micro-CT imaging revealed significant deformation of the screen mesh wick structure, characterized by buckling and separation of the wick from the inner wall of the heat pipe container. Conversely, the biased screen mesh heat pipes demonstrated excellent resilience to bending, with minimal decrease in heat transfer limit (<6 %) and no observable deformation to the wick structure. As such, biased screen mesh heat pipes offer clear advantages in applications requiring complex routing, where increased design flexibility and robust thermal performance are critical.