Study on the permeability and capillary pressure of spiral woven mesh for flat-plate heat pipes

Due to its excellent capillary characteristics, spiral woven mesh is widely used as the wick structure in ultra-thin flat-plate heat pipes. The performance of these heat pipes surpasses that of conventional ones using sintered powder or multi-layer mesh structures. However, precise quantitative studies on the permeability and capillary pressure characteristics of this unique porous structure are lacking. In this work, we systematically investigated its permeability and capillary pressure, as well as their relationship with the structure. Based on experimental results, we demonstrated that numerical simulation of periodic microelements and subsequent area weighting can accurately predict the permeability of actual structures. Additionally, a parametric study was conducted, yielding a unified empirical relationship between permeability and the structural parameters. In the part of capillary pressure, U-shape tube gravity method was utilized and the relationship between capillary pressure and structure was also disclosed. This study will provide reliable data and theoretical guidance for calculating the capillary limit in heat pipes using spiral woven mesh as the wick.