A structured surface for high performance evaporative heat transfer

An evaporative surface is described for heat pipes and other two-phase heat transfer applications that consists of a hybrid composition of V-grooves and capillary wicking. Characteristics of the surface include both a high heat transfer coefficient and high heat flux capability relative to conventional open faced screw thread surfaces. With a groove density of 12.6/cm and ammonia working fluid, heat transfer coefficients in the range of 1 to 2 W/sq cm K have been measured, along with maximum heat flux densities in excess of 20 W/sq cm. A peak heat transfer coefficient in excess of 2.3 W/sq cm K at 20 W/sq cm was measured with a 37.8/cm hybrid surface.