On the evaporation of superheated water drops formed by flashing of liquid jets

The flash evaporation of superheated water in direct contact with its own vapor involves very high heat transfer rates and the existing solutions for the problems of heat diffusion in the superheated water drops underestimate the actual heat transfer rates, even when the gas-side heat transfer coefficient is assumed to be extremely high. This happens due to the poor thermal conductivity of the water which causes the heat transfer to be dominated by the heat flow within the liquid. Accommodation between the analytical results of the heat diffusion in superheated water and those obtained from the experimental measurements requires considering the effective thermal conductivity of the liquid owing to the violent nature of the flow, which is thought to be much larger than the mere molecular thermal conductivity. This paper presents initial attempts on modeling the liquid-side heat transfer process accompanying the surface evaporation of superheated water drops resulting from the flashing of superheated water jets. (C) 2011 Published by Elsevier Masson SAS.