Boiling Heat Transfer Enhancement in Liquid Nitrogen Using Surface-Cracked Acrylic Coatings

A coating with surface-crack structures was observed to promote boiling heat transfer. An acrylic resin that develops cracks on its surface through natural drying was applied to a copper plate; subsequently, quenching experiments using liquid nitrogen were conducted. As a result, boiling heat transfer enhancement was observed across almost the entire temperature range during the cooling process, and the cooling time was considerably shortened. Near room temperature, complete film boiling disappeared, and an increase in heat flux was observed compared with the bare surface. In addition, the critical heat flux increased to approximately twice that of the bare surface. It is highly likely that the enhancement of surface wettability because of surface roughness contributed to boiling heat transfer enhancement.