Transition Boiling Heat Transfer of Droplet Streams and Sprays

An experimental study was performed to characterize the transition boiling heat transfer rate from a surface to a stream of impinging water droplets and to extrapolate this information to predict the transition boiling heat transfer of a dilute spray. First, transition boiling heat transfer data were gathered for a continuous stream of monodispersed water droplets striking a polished nickel surface. From these data, empirical correlations were developed to describe the heat transfer rate and heat transfer efficiency for droplet velocities between 1.0 m s(-1) and 7.1 m s(-1), droplet. diameters ranging from 0.250 x 10(-3) m to 1.002 x 10(-3) m, and surface temperatures covering 110-240 degrees C. By properly accounting for the hydrodynamic differences between a spray and a single droplet stream, the empirical single droplet stream heat transfer correlations were effectively extrapolated into a model for predicting the transition boiling heat flux of dilute sprays (Q " approximate to 0.5 x 10(-3) m(3) s(-1) m(-2)).