Comparison of pool boiling performance for plain micro-fins and micro-fins with a porous layer

Abstract

The paper focuses on the comparison of pool boiling heat transfer on micro-fin enhanced structures with and without porous covering. The purpose of the present study was to find the optimal parameters of the perforated foil or wire mesh sintered to the micro-fin tips to provide the highest heat transfer coefficient. Additionally, a simplified model was proposed for determining total heat flux for investigated surfaces.Three types of structured surface were used: 1.0 mm high plain micro-fins (designated as MF), enhanced surfaces made by sintering micro-fin tips with the copper perforated foil (MF+F) and structured surfaces formed by sintering the woven copper wire mesh to the micro-fin tips (MF+M).The experiments were carried out for water, ethanol, Novec-649 and FC-72 at atmospheric pressure. At medium and high heat fluxes for water, low and medium heat fluxes for ethanol and medium heat fluxes for FC-72, surfaces with micro-fins covered with wire mesh produced the highest heat transfer coefficient. The plain micro-fin surfaces helped obtain the increase in the heat transfer coefficient value about two times higher than that of the micro-fins with perforated foil at FC-72 boiling for high heat fluxes. The simplified semi-analytical model was proposed for determining total heat flux for the studied surfaces. The model provided a heat flux prediction with a ±30–40% margin of error.