Film condensation in presence of non-condensable gases: Interplay between variable radius of curvature and interfacial slip

A theoretical study has been executed to investigate the implications of interfacial slip in presence of non-condensable species in the bulk mixture of vapour on heat transfer characteristics in film condensation over horizontal tubes with varying radius of curvature. A polar surface comprising a segment of an equiangular spiral in the form of Rp = aemθ (a and m being parametric constants), generated symmetrically on a vertical chord, has been considered. We reveal that there is a substantial enhancement in the rate of condensation heat transfer due to an effective interfacial slip at the solid–liquid interface. The enhancement in condensation heat transfer due to solid–liquid interfacial slip is more pronounced in the case of vapour with non-condensable species, but less pronounced for higher values of m (a surface profile parameter).