Liquid Film Distribution of Vapor Condensation in Horizontal Tubes

Abstract

The thickness of a liquid film formed by condensation in a horizontal tube was measured using the difference of the dielectric constant between vapor and liquid. And flows were classified into annular and semiannular flow applying these experimental results. It was found that the transition between annular and semiannular flows did not depend on liquid velocity but occurred at a specified vapor velocity. Although this vapor velocity differs according to specific weight of the refrigerant, the transition occurs at a modified Froude number F_r=1.5. The liquid film thickness formed at the upper part of a tube is determined from the ratio of the shearing stress caused by flowing vapor to the shearing stress caused by the falling liquid film for the semiannular flow. And a semiannular flow model based on this relation shows good agreement with experimental results concerning to both the liquid film thickness and the transition condition.