A Two-Dimensional Numerical Analysis of Transient Falling-Film Hydrodynamics on Horizontal Tubes

Abstract

Falling-film hydrodynamics and heat transfer, a cutting-edge technology, has been widely used in a variety of industrial applications, including desalination and refrigeration. In this study, a two-dimensional and two-phase model was developed to examine the microscopic flow mechanism and transient flow characteristics. Film thickness varies with sprinkle density in the impingement, propagation, and accumulation zones, with the thinnest film appearing between 90° and 140°. In both the unsteady and steady cases, the film thickness over the stabilizing tube is nearly the same. Due to the acquired momentum of the liquid film, the propagation time for the test tube was also shorter than that of the stabilizing tube. Low sprinkle density results in dry regions; high sprinkle density results in mal-distribution, the formation of recirculation zones beneath the tubes, air cavities in the flow field, wavy disturbances in the liquid profile, and fluid waste. Furthermore, as the liquid sprinkle density increases, the developed recirculation zones and air cavities beneath the tubes expand and become modified. A sprinkle density can be set just above the minimum value to achieve steady-state film thickness. The findings can be used to improve flow characteristics and avoid over commitment and insufficient liquid supply.