Critical height of micro/nano structures for pool boiling heat transfer enhancement

Abstract

Critical heat flux (CHF) enhancement by surface modifications has been an extensively researched area in pool boiling heat transfer. Here we report a fundamental mechanism of CHF enhancement where nano/micro ridges are fabricated on surfaces to fragment and evaporate the metastable non-evaporating/adsorbed film present at the base of a bubble in the contact line region. CHF increase of ∼125% is obtained with only ∼40% increase in surface area. An analytical model is extended to explain the CHF enhancement and to determine the average non-evaporating film thickness, which serves as the critical height for nano/micro structures for pool boiling heat transfer enhancement.