Evaporation Heat Transfer of Falling Films on Horizontal Tube : 1st Report, Analytical Study

Abstract

Evaporation heat transfer of saturated falling film on a horizontal tube was studied analytically. For laminar flow, a model comprised of the developing, transitional, and developed regions was proposed. The boundary layer integral method was used to reach a closed-form solution. A third-order polynominal temperature profile was assumed in the developing region, and a linear profile in the developed region. Both profiles smoothly joined in the transition region. From this analysis, the Nusselt number was presented as a function of film Reynolds number, Prandtl number, and dimensionless tube radius. The same type of correlation was developed for turbulent flow with the eddy viscosity model, and the Nusselt number was obtained as a function of film Reynolds number and Prandtl number.