Wall heat flux partitioning analysis for subcooled flow boiling of water-ethanol mixture in conventional channel

Abstract

In the present study, heat transfer coefficient of water-ethanol mixture in the subcooled boiling region is determined in a rectangular conventional channel (Channel size ≥3 mm). When the heat flux and mass flux increase it is observed that heat transfer coefficient increases. But the effect of heat flux is significant when compared with that of mass flux in the subcooled boiling region. It is found that maximum and minimum heat transfer coefficient are observed for mixture with 25% Ethanol volume fraction and 75% Ethanol volume fraction respectively. Wall heat flux partitioning analyses is carried out for mixture with different ethanol volume to determine the contribution of heat flux towards convection, agitation and evaporation. It is also found that heat flux due to convection decreases with increase in heat flux at partial and fully developed nucleate boiling heat regions for all volume fractions. The heat flux determined from the partitioning analysis are lower than the experimentally determined heat flux values at the partial nucleate boiling region and are higher at the fully developed boiling region.