Effect of hydrophilic coating on mesh wicks used in heat pipes

Heat pipes are efficient heat transfer devices which utilize two-phase flow for high heat flux removal and finds applications in many industries. Copper meshes are extensively used in heat pipes and their performance primarily depends on the wettability which is an important design criterion. The wettability and hence the thermal performance can be improved by providing a hydrophilic coating using sol-gel technique. The effect of the binder additive, namely, polyethylene glycolconcentrations, dipping time and dipping frequency on wettability and thermal performance are investigated in this study. It is found that coating on mesh reduces the contact angle and the wettability is improved by 32%. The results indicate that dipping frequency has significant effects on thermal performance due to the existence of hair-like microstructures. The coating is found to offer good thermal performance and reduces the surface temperature of heat pipe by 23 K at 180 W.