Laminar Film Condensation of Pure Saturated Vapors on Inclined Circular Cylinders

Abstract

Abstract Laminar film condensation of pure saturated vapors on inclined circular cylinders is treated analytically. The analysis is based on, and made under the same assumptions of, Nusselt’s theory of film condensation. Experiments were performed to check the analytic results. In the analysis, the problem is expressed in terms of dimensionless groups and the solution gives, in these terms, the local film thickness at any point on the surface of a cylinder. From the results of the analysis one can obtain the local film coefficient, and hence a mean film coefficient for the entire surface of any cylinder at any inclination. The analysis shows that every tube has an optimum inclination at which the rate of condensation on the entire tube is a maximum. The experiments were carried out by condensing steam on the inside surface of a thick copper tube 1¼ in. diam and about 8⅛ in. long. The actual film coefficients obtained during the experiments were 28 to 100 per cent higher than those predicted by the theoretical analysis. The deviation from the theory increased with the inclination of the tube and the temperature difference between the tube surface and the steam.