Abstract
Steady-state and transient boiling CHFs in a pool of highly wetting liquid were studied. Boiling heat transfer processes on a platinum cylinder in a pool of ethanol due to exponentially increasing heat generation rates, Q=Q_0exp^<t/τ>, ranging from quasi-steadily increasing one to rapidly increasing one with periods, τ, were measured for a 1.0-mm diameter horizontal cylinder with different surface conditions of commercially-available and roughly-finished surface cylinders for saturated and subcooled liquid at various pressures. Steady-state CHFs at various pressures gradually increased with an increase in subcooling. It was confirmed that the CHFs for lower subcoolings at pressures almost show little dependence on cylinder surface condition. However the CHF data for the roughly-finished cylinder in many cases were increased for higher subcoolings at pressures. Typical trends of the CHFs were clarified to three groups corresponding to periods; the first, second and third groups of CHF were for longer periods, for shorter and for intermediate ones. It was clarified that the CHFs for the shorter periods were significantly affected by the surface roughness of cylinders. It appears that more study on the multi-parametric surface conditions and a wider range of experimental conditions need to be included in the study.
