Abstract
Wicks with longitudinally variational wettability will be adopted to improve the thermal performance of heat pipes. Visualization and simultaneous performance measurements will be made using a specially designed flat-plate heat pipe test apparatus with a glass wall. In general, good wettability in the evaporator enhances thin-film evaporation and increases the maximum heat load. Dropwise condensation with poor wettability leads to higher condenser performance. Therefore, wicks will be treated to exhibit high wettability at the evaporator and low wettability at the condenser. The effects of variational wettability on the evaporation and condensation characteristics will be observed and quatitatively measured.