The Computational Modeling of Falling Film Thickness Flowing over Evaporator Tubes

Abstract

This paper presents a computational modeling of water falling film flowing over the horizontal tubes of evaporator. The objective of this study is to use numerical predictions for comparing the film thickness along circuferential direction of tube on 2-D CFD models. The results are then validated with a verification of correlation in previous literatures. A comprehensive design of 2-D models have been developed according to the real application and actual configuration of the falling film evaporator as well as previous experimental parameters. A computational modeling of the water falling film is presented with the aid of Ansys Fluent softwares. The Volume of Fluid (VOF) technique is adapted in this analysis since its capabilities of determining the film thickness on tubes surface is highly reliable. The numerical analysis is carried out under the influence of the pitch tube at temperature of 27°C and ambient pressures. Three types of CFD numerical models were used in this simulation with tubes spacing of 30 mm, 20 mm and 10 mm respectively. The use of a numerical simulation tool on water falling film has resulted in a detailed investigation of film thickness. Based on the numerical simulated results, it is found that the average values of water film thickness for each model are 0.1858 mm, 0.1904 mm, 0.2052 mm, and 0.2200 mm.