3D Analysis of Film Thickness Distribution in a Horizontal Type Falling Film Evaporator

EasyChair Preprint no. 5761

Abstract

The film thickness characterization in the horizontal type falling film evaporators have been the primary focus of research in the past decade. Several experimental and numerical studies have been carried out to analyze film thickness distribution around horizontal tube. Because of experimental setup limitations, thickness measurements on complete tube area are not conceivable. However, numerical studies allow researchers to characterize falling film under flexible operating conditions. Present study focuses on quantification of film thickness distribution around horizontal tube in a three dimensional domain. Two tubes of 25.4 mm diameter have been selected for the computational fluid dynamics (CFD) simulations, with an orifice of 2x1 mm², an impingement height of 2 mm and an inter-tube spacing of 7.6 mm. The tube section of 22 mm has been opted as per critical wavelength formulation/distance between droplet sites. In order to reduce computational efforts, only quarter of the domain is considered for numerical calculations. The CFD model has been established in Ansys fluent v18.0 and has been validated quantitatively against Nusselt correlation and qualitatively with the experimental data available in the literature. The film thicknesses at different axial positions z = 0, 5.5 and 11 mm have been computed and compared and results show higher film thickness distribution at z = 0 mm (in line with droplet formation site) as compared to that of z = 11 mm (halfway between two droplet formation sites). The film thickness at θ = 90° is found to be 0.195 mm at z = 0 mm which is 21.1% higher than that of z = 11 mm.

Keyphrases: 3D, CFD, Falling film, Film thickness, Horizontal tube, numerical model

@Booklet{EasyChair:5761,
  author = {Furqan Tahir and Abdelnasser Mabrouk and Muammer Koc},
  title = {3D Analysis of Film Thickness Distribution in a Horizontal Type Falling Film Evaporator},
  howpublished = {EasyChair Preprint no. 5761},

  year = {EasyChair, 2021}}