Minimum heat flux (MHF) behavior with different surface characteristics including structured surfaces and different surface energies

Abstract

In a series of quenching experiments with smooth structure hydrophilic/hydrophobic surfaces, the effects of surface wettability and surface structures on the minimum heat flux (MHF) behavior are observed. For a hydrophilic structure surface, early transition from film boiling to transition boiling at the MHF point occurs at the highest temperature (324 degrees C) in this experimental study. A smooth hydrophilic surface has 274 degrees C as the MHF temperature while a hydrophobic smooth surface shows the MHF behavior at lower temperature (208.8 degrees C). In contrast, there is no observable film destabilization with an observable MHF behavior on a hydrophobic structured surface during the quenching process. The test results are described by considering liquid-solid intermittent contact with an oscillating film interface in this study. For the intermittent contact, an equilibrium condition is proposed to describe the boiling transition with surface characteristics. (C) 2018 Elsevier Ltd. All rights reserved.