THEORETICAL ANALYSES OF VAPOR CONDENSATIO N ON LAMINAR LIQUID JET OR DROPLET EFFECT OF CONDENSED FILM

In the heating of a cylindrical laminar liquid jet or a droplet by the condensation of the saturated vapor, the effects of the condensed fil m have been analysed. Theoretical solutions have been derived to evalu ate the non-dimensional average temperature and Nusselt number in the heating of a cylindrical liquid jet or a droplet, separately. Based on the theoretical solutions in the heating of a cylindrical liquid jet, the effects of the dominant parameters, such as the ratio of thermal conductivity of the condensed liquid film to that of the liquid jet, J acob number of the vapor and the ratio of heal capacity of the condens ed liquid film in unit volume to that of the liquid jet, are discussed . It is found that the effects of the condensed liquid film in the hea ting of a cylindrical liquid jet or a droplet by the condensation of t he vapor are more important in the case of smaller Graetz number or la rger Fourier number. Approximate solutions to estimate the non dimensi onal temperature and Nusselt number have been also derived for the cas e of smaller or larger Graetz (Fourier) number, Relative accuracies an d effectiveness of the approximate solutions for a cylindrical liquid jet are discussed in the present paper.