Design considerations of high heat flux heat pipe evaporators

A numerical model was developed to describe the liquid and vapor flows inside porous wicks in heat pipe evaporators. The evaporator design parameters, including pore radii distribution, wick permeability and thickness, were calculated for various heat flux conditions. The vapor fraction, defined as the percentage of wick volume occupied by the vapor, was found to be highly dependent on the pore radii distribution and critical in determining the heat flux limit of the evaporator. The model was compared to previous experiments and other models to verify its accuracy. It can be used for design of high heat flux heat pipes for cooling of high power electronics.