Effective and uniform cooling on a porous micro-structured surface with visualization of liquid/vapor interface

Abstract

This study examines cooling efficiency, uniformity, and bubble dynamics on a porous surface. We use infrared (IR) thermometry to visualize results of temperature fields and liquid/vapor interfacial dynamics. Porous and non-porous micro-structured surfaces are prepared using soft-lithography and a ceramic precursor, allylhydropolycarbosilane (AHPCS). The surface cavities promote nucleation, and the heat transfer coefficient on the porous surface is approximately 30% higher than that on the non-porous surface. Additionally, the porous surface exhibits a more uniform temperature field with lower spatial and temporal variations than the non-porous surface. Bubble dynamics is visualized via an IR camera through the bottom side of the test specimens using the IR transparent characteristics of the substrate and micro-structures. The porous surface reveals higher nucleation site density and contact line density and lower equivalent bubble diameter when compared with those of the non-porous surface, and this is consistent with more effective and uniform cooling on the porous surface.