based on the stagnant film model of a boundary layer [16], was first suggested by Spalding [10] to correct for the effect of interfacial mass transfer on diffusion in real boundary layers. This expression is also plotted in Pig. 1. While Nu/Nuo values from equation (13) do not coincide exactly with those indicated by the laminar-boundary-layer calculations, they are nevertheless comparable in form and magnitude for Pr » 1. Moreover, since it has been widely used with considerable success for mass transfer at complex surfaces submerged in laminar or turbulent flows (see, e.g., [17,18]) equation (13) is expected to correctly account for the effects of melting in many complex flow systems [4].