Numerical investigation on interfacial characteristics of steam bubble condensation in subcooled water

Numerous direct-contact condensation (DCC) and boiling issues are numerically investigated with the Lee model under an assumed constant mass transfer coefficient through trial and error. A new mass transfer coefficient correlation is proposed, and the accuracy of the correlation is confirmed via comparison to Kim and Park' experimental results from steam bubble injected vertically into a flow channel with diameter of 4.9 mm and subcooled temperature of 12 K in this work. The established correlation reveals that a fixed mass transfer coefficient value throughout the whole bubble condensation process is unreasonable and may cause solution divergence. Moreover, values of the mass transfer rate and velocity at the steam-water interface are explicitly derived at several moments. The results demonstrate that the mass transfer rate causes velocity fluctuations at the steam-water interface, and these velocity fluctuations promote bubble deformation, which in turn affects the condensation mass transfer rate.