Entropy Analysis of Complete Condensation of Saturated Steam on a Vertical Wall Using Nusselt Velocity and Temperature Profile in a Condensate Layer

Abstract

In this paper an analytical model for calculation of entropy production for Nusselt model of condensation of pure substance vapour is given. Model development starts from basic two-dimensional integral equation for entropy production and describes film condensation on a vertical wall. Model covers entropy production, which is a result of two-dimensional heat transfer in a condensate layer, existence of velocity gradient and condensate layer viscosity. Entropy contribution of each of the members is explicitly derived in a closed form and the results of calculation are shown in the appropriate diagrams. Diagrams present film condensation of dry saturated water steam and dry saturated ammonia steam, both with saturation temperature of 100 °C with surface wall temperature of 98.5 °C. Obtained equations and presentation of the related results have shown that dominant entropy production is directly connected only with heat conduction in y-axis direction, where y-axis corresponds with thickness of condensate layer.