ABSTRACT
The literature on heat transfer in two-phase films goes back to Nusselt who obtained in terms of a Rayleigh number based on latent heat Nu=f(Ra2) or, explicitly, Nu~Ra21/4, for laminar films. This relation is implicit in the similarity solution of Sparrow and Gregg for the laminar film condensation of saturated vapor next to a vertical isothermal wall. The foregoing dimensionless numbers result from the coupling of appropriate (inertial, viscous and buoyant) forces of the momentum balance with enthalpy flow and conduction terms of the thermal energy balance. This chapter aims for correlation of two-phase turbulent films. The fundamental significance of Π2 for two-phase films appears to be sofar overlooked except for the recent work of Arpaci and Larsen, Arpaci, et al., Arpaci and Kao.
