Rotating heat pipe performance with internal wire mesh screens

摘要

The performance of a rotating heat pipe was optimized in terms of the fluid charge ratio, speed of rotation, tapering angle together with relative positions, and the packing ratio of porous filling screens. The favourable effect of porous layers was testified by employing an inner liner along the whole tube interior surface to enhance both evaporation and condensation. The porosity effect was extended to include the whole pipe cross-section such that different configurations of screen layers packed together to form a turbulent extended heat transfer corrugated surface were investigated. It was found that the longitudinal temperature distribution along the heat pipe became more uniform as both the speed of rotation and the tapering angle increased, thus indicating a decrease in the heat pipe thermal resistance. Owing to the fact that enhanced evaporation and condensation take place, the overall heat transfer coefficient increased and the thermal capacity operational limits were extended by increasing the centrifugal acceleration within the stratified flow regime across the speed range of 0–700 r/min. The insertion of porous screens increased the rates of turbulent heat and mass transfer as well as the optimum charge ratio. By optimizing the porous configuration in terms of number of layers and bore size, the decrease in longitudinal temperature difference due to enhanced convection over-rode the increase in saturation temperature difference due to pressure drop. The increased fluid temperature uniformity in the core region, accompanied by severe radial temperature gradients close to the wall, thus revealed increased rates of convective heat transport.