The Peak Boiling Heat Flux in Saturated Ethanol-Water Mixtures

The present work provides original measurements of the burnout heat flux in saturated ethanol-water mixtures, over the full range of concentrations. These data were obtained at atmospheric pressure on horizontal cylinders, ranging from 0.51 to 2.16 mm in diameter. They reveal significant improvements of the peak heat flux for mixtures, over that which would be expected from pure fluids with the properties of the mixture. This improvement is most pronounced at low ethanol mass fractions. McEligot has suggested that the improved heat flux results from a subcooling created by selective distillation at the liquid-vapor interface. Combining this idea with a recent correlation of subcooled burnout, we estimate the extent of effective subcooling qualitatively and discuss the use of this estimate to correlate burnout in binary mixtures. Two dimensionless groups are proposed to characterize this effective subcooling, both based on appropriate characterizations of the phase equilibrium diagram.