Abstract: The mechanically pumped two-phase fluid loop (MPTL) is a thermal management system with high heat transportation capacity and precise temperature control. The accumulator, a key component of MPTL, regulates the system performance through its capillary structure. This study proposes a novel accumulator using multilayer metal wire mesh to capture, store, and transport liquid within the loop. Metal wire meshes offer high porosity for capillary-driven liquid flow and maintain structural integrity during thermal cycling with assembly stress. The capillary porosity can be flexibly tailored through the composite layering of meshes with different mesh numbers. The specially designed mesh stacking configuration creates vapor retention space, which facilitates gas-liquid separation of the incoming fluid. Theoretical analyses show that 300-mesh wire screens with optimized porosity provide sufficient pumping capability. Their high surface-area-to-volume ratio and low flow resistance ensure excellent mass transfer efficiency, making them ideal capillary structures. An experimental platform with a visible accumulator prototype is established to investigate the capillary flow characteristics of different working fluids and evaluate accumulator performance. Experimental results show that the wire mesh structure effectively enables capillary transport for both working fluids, with the climbing velocity governed by fluid properties such as surface tension, viscousity, and density. The developed dynamic capillary rise model, which accounts for the inertial effects of the flow, describes the capillary action within the multilayer wire mesh. Relative errors between model simulations and experimental data are 19.3% for water and 1.7% for ethanol. Moreover, when the system operation state varies, the accumulator effectively suppresses pressure oscillations by supplying capillary-driven fluid compensation to the loop.