Simplified expression for efficiency of spray flash evaporation.

Abstract

Based on the authors' previous experimental studies of spray flash evaporation occurring in a superheated water jet ejected from a simple tubular nozzle into a low-pressure vapor zone, a simplified expression for the efficiency of flash evaporation, η, was derived asη=1- {1+kΔTs (t-t0)} -1where, k is an empirical coefficient, ΔTs the superheat of liquid at the nozzle exit, t the residence time of jet in the flash chamber and t0 the time lag of the initiation of flashing.It was realized that, for those cases in which bubble nuclei were sufficiently injected by electrolyzing warm feed water, the empirical coefficient k became practically independent of the nozzle diameter, the flow rate of liquid and the superheat of liquid at the nozzle exit, and increased up to 91s-1 K-1 on average at 60°C jet inlet temperature.