Flash evaporation from a water pool: Influence of the liquid height and of the depressurization rate

This article presents a study about the influence of the initial water height and of the depressurization rate on the flash evaporation of a water film. Experimental study is carried out with initial water height ranging from 25 to 250 mm, superheats between 2 and 44 K, and an initial liquid temperature from 45 to 85 degrees C. Visualization of the phenomenon using a CCD camera lets us firstly point out the influence of the initial water level on the flashing phenomenon in a qualitative way. Thermal balance allows us to correlate the mass evaporated with the liquid temperature, and then to quantify the influence of the initial water height on several parameters: maximal amplitude of the phenomenon, flashing time, liquid mass evaporated. We also analyse influence of relatively low depressurization rate (from 0 to 3.5 bar(.)s(-1)) on the flashing time, the mass evaporated, and the mass flow rate. Finally, dimensionless correlations between these parameters are proposed. (c) 2005 Elsevier SAS. All rights reserved.