MASS TRANSFER COEFFICIENT IN THE CASE OF BRAKE-UP OF A CONTINUOUS FALLING FILM.

Two-phase flow of the thin, vertical liquid film and the counter-current air flow are studied experimentally in conditions in which liquid film brakes up. Parameters related to the two-phase flow are shown as a function of the ratio between the liquid flow rate and air flow rate and film Reynolds number. All relevant parameters change in time, so their values are shown for two time periods: when break-up starts and after a two and a half hours when final value of the degree of the wetted area is reached. Mass transfer coefficient is a function of the film Reynolds number and time, and it increases as film Reynolds number increases but decreases in time as surface de-wetting occurs. Proportion of wetted surface area as well as value of evaporated water vapour, changes as process of falling film break-up occurs. [ABSTRACT FROM AUTHOR]