Nucleate pool boiling over vertical steps

Nucleate subcooled pool boiling of water over vertical steps was carried ou t under atmospheric conditions. Two forward-facing steps of 0.8125 and 0.50 in. were considered. Data were statistically analyzed to determine samplin g error. The ebullition was qualitatively explained in terms of thermal/flo wfields and bubble dynamics, Plots of boiling heat flux vs superheat and su rface heat transfer coefficient vs heat flux have been provided. Empirical correlations, developed from the above mentioned data, are also presented. Boiling on vertically extended surfaces shelf ed an increase in heat flux f or a given superheat when compared with a plain vertical surface because of fluid agitation in the region of the step. The parameters associated with bubble dynamics and bubble interactions were also qualitatively discussed.