Enhanced capillary pumping performance of flexible heat pipe device with multi cross-section ultra-thin wick

Copper mesh, with its excellent flexibility and thermal conductivity, is an ideal material for the wick of flexible heat pipe. In this paper, a structure optimization strategy of wick with multi cross-section is proposed to enhance its capillary pumping performance. The analytical solution models of single-section and multi cross-section wicks are established by the kinetic equation of capillary pumping. Numerical simulation is used to analyze the capillary pumping performance of the multi cross-section wicks, and the results confirm the multi cross-section enhancement mechanism with the infrared experimental results. Laser processing, sintering and molding, and super-hydrophilic modification are used to fabricate the multi cross-section wick. Laser removal of rectangular units can modulate the capillary pumping performance of the multi cross-section wick. The capillary height h of the multi cross-section wick is enhanced by 13.4 % when the size of the rectangular unit l x w = 40 mm x 1.5 mm and the number of removals N = 5. Compared with the heat transfer performance of the single cross-section flexible heat pipe, the evaporator temperature T and thermal resistance R of the multi cross-section flexible heat pipe decreased by 16.6 % and 77.4 %, respectively. The effective thermal conductivity Keff reaches 10,560 W/ (m & sdot;K), which is 26 times higher than that of copper.