Numerical simulation of liquid falling film on horizontal circular tubes

doi:10.1007/s11705-012-1296-z

Front Chem Sci Eng

2012, Vol. 6

Issue (3) : 322-328 https://doi.org/10.1007/s11705-012-1296-z

RESEARCH ARTICLE

Numerical simulation of liquid falling film on horizontal circular tubes

Fengdan SUN, Songlin XU(

), Yongchuan GAO

Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

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Abstract

The objective of this study is to investigate numerically the flow characteristics of falling film on horizontal circular tubes. Numerical simulations are performed using FLUENT for 2D configurations with one and two cylinders. The volume of fluid method is used to track the motion of liquid falling film and the gas-liquid interface. The effect of flow characteristics on heat and transfer coefficient may be remarkable, although it has been neglected in previous studies. The velocity distribution and the film thickness characteristics on the top tube, some special flow characteristics on the bottom tube, intertube flow modes and effect of liquid feeder height on flow characteristics have been studied. Our simulations indicate that 1) the velocity distributions of the upper and lower parts of the tube are not strictly symmetric and non-uniform, 2) the film thickness depends on flow rate and angular distributions, 3) the flow characteristics of the top tube are different from those of the bottom tube, 4) three principal and two intermediate transition modes are distinguished, and 5) the liquid feed height plays an important role on the formation of falling film. The numerical results are in a good agreement with the theoretical values by the Nusselt model and the reported results.

Keywords falling film horizontal tube flow characteristics film thickness liquid feeder height

Corresponding Author(s): XU Songlin,Email:slxu@tju.edu.cn

Issue Date: 05 September 2012

Cite this article:

Fengdan SUN,Songlin XU,Yongchuan GAO. Numerical simulation of liquid falling film on horizontal circular tubes[J]. Front Chem Sci Eng, 2012, 6(3): 322-328.

URL:

https://academic.hep.com.cn/fcse/EN/10.1007/s11705-012-1296-z
https://academic.hep.com.cn/fcse/EN/Y2012/V6/I3/322

Fig.1 The physical model of horizontal tube

Fig.2 Numerical model with the boundary conditions

Tab.1 The numerical range of the physical variables

Tab.2 Fluent 2D simulation settings

Fig.3 Film thickness at different mesh

Fig.4 Flow features of the velocity contour

Fig.5 Velocity profile on different cross sections

Fig.6 Fluctuations in film thickness versus time

Fig.7 Variations of film thickness along angular position

Fig.8 Contours of falling film on horizontal tubes

Fig.9 Variations of film thickness along angular position

Fig.10 The idealized inter-tube falling film modes (Mitrovic): (a) droplet, (b) column, and (c) sheet

Fig.11 Contours of falling film between two horizontal tubes

Fig.12 Effect of liquid feed height on the behavior of falling film

Fig.13 Effect of liquid feed height on film thickness

Fig.14 Comparison the simulated film thickness at different velocities with the theoretical values by the Nusselt model

Fig.15 Comparison of the simulated film thickness at diffent angles with those reported by Ouldhadda et al.

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