Phase-Change Heat Transfer in Micro-Capillary Grooves

Abstract

In the present paper, an experimental investigation about the phase-change heat transfer is performed on a vertical plate with rectangular micro-capillary grooves. The heat transfer is much enhanced compared to the pool nucleate boiling on a smooth surface. Boiling occurs, and vapor bubbles grow rapidly and rapture in the microgrooves as the wall heat flux is higher, while the heat transfer on the groove surface is a pure evaporation process at lower superheat. For smaller height surface, the mechanism of critical heat flux (CHF) is the same as that in usual pool boiling, but liquid supply limitation is essential to the maximum mean wall heat flux for larger height surface. The CHF is independent of the gravity. Furthermore, the experiment verified that the evaporative heat transfer only on the stable contact line (or meniscus) is small and incomparable to the value of CHF in usual pool boiling.