Studies on pool boiling heat transfer (modification of correlation of macrolayer thickness and measurements of macrolayer thickness at low heat fluxes)

Abstract

The macrolayer thickness at critical heat flux has been determined based on the energy balance relation qCHF = ρlH fg δl. f, with measurements of the critical heat flux and the detachment frequency of vapor masses (coalesced bubbles) for various liquids at pressures from 0.05 MPa to 0.35 MPa for upward and vertical 20 mm diameter disk heaters. The macrolayer thickness correlation proposed in the fourth report of this series by Kumada and Sakashita was modified with the data obtained in the present report. Macrolayer thicknesses at low heat fluxes for water and ethanol under atmospheric pressure were also measured while changing the orientation of the heating surface from vertical to downward. The measured macrolayers at low heat fluxes were thinner than those by obtained from existing data measured by a probe method in the nucleate boiling region