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Indexed by:期刊论文

Date of Publication:2018-08-01

Journal:DESALINATION AND WATER TREATMENT

Included Journals:SCIE

Volume:124

Page Number:98-105

ISSN No.:1944-3994

Key Words:Sheet flow; Two-phase flow; Geometrical structure parameters; Film thickness

Abstract:The flow characteristics of falling film outside horizontal round- and elliptical tubes are simulated based on a finite volume solution to the Navier-Stokes equations coupled with the volume of fluid method at a liquid-vapor interface. A two-dimensional multi-phase flow model is developed using adiabatic conditions for the sheet flow, where the tube walls are assumed, in practice, to be completely wetted by liquid water. The effects of the tube arrangement, inter-tube spacing, liquid feeder height, and tube shape on the thickness distribution of a liquid film in the circumferential direction are presented in detail. The results show that the tube arrangement has little effect on the first row of tubes, and a significant effect on the second row of tubes, under a fixed fluid flow density. The film thickness decreases with an increase in the inter-tube spacing. The higher feeder height leads to a thinner film. In addition, the film thickness outside the elliptical tube is more unique compared with that of a circular tube. The lesser effect of wake turbulence and the larger developed film region outside an elliptical tube have more advantages in terms of the heat transfer process. The results can provide the basis and guidance for further research on and development of an efficient horizontal-tube falling-film evaporator.