Heat and Mass Transfer Characteristics of Alkali Metals in a Combined Wick of High-Temperature Heat Pipe

To study the heat and mass transfer characteristics of alkali metals in a combined porous wick in high-temperature heat pipes, a three-dimensional (3-D) numerical model is constructed by using the finite volume method, Darcy's theory, and the theory of local thermal equilibrium. The research finds that the pressure drop of fluids flowing through a combined porous wick exhibits an increasing trend with increasing flow velocity at the inlet and with decreasing permeability of the porous media; a combined porous wick of lower porosity and permeability and larger fluid velocity at the inlet is found to have a less uniformly distributed fluid velocity; the different temperatures of the fluid at the inlet mainly influence the inlet section of the computational model, while having negligible effect thereon in the axial direction (this embodies the thermal homogeneity of such heat pipes). The result reveals that the temperature change in fluids at the inlet does not significantly affect the overall temperature distribution in a combined wick.