Numerical analysis on heat transfer of porous wick flat micro heat pipe under various operating conditions

Abstract

Flat micro heat pipes (FMHPs), which have excellent heat transfer performance, have been widely applied in thermal management. A three-dimensional transient numerical model of an FMHP with copper foam and spiral woven mesh composite wick is developed in this work. The volume of fluid method is utilized to simulate the vapor-liquid phase change and circulating flow in the FMHP. The effect of unsaturated flow in porous media is considered in the composite wick domain, which improves the accuracy of simulations of porous wick heat pipes at high heat fluxes. The simulation and experimental results are in good agreement, with the maximum relative uncertainty of about 1.03%. The heat transfer performance of the FMHP is simulated and analyzed at different heat fluxes, tilt angles, and heat dissipation conditions. The results show that the wall temperature of FMHP reaches a steady state in <30 s under different working conditions. Compared with the horizontal condition, the total thermal resistance decreases by about 16% when the tilt angle is 30°. These simulation results provide valuable references in selecting the operating environment, mounting method, and cooling conditions of the FMHP.