Numerical simulation of liquid falling film on horizontal circular tubes

Numerical simulation of liquid falling film on horizontal circular tubes

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

参考文献

[1] Nusselt W. Die Oberflächenkondensation des Wasser-dampfes. Zeitschr Ver Deut Ing, 1916, 60(27): 569–575

[2] Adams F W, Broughton G, Conn A L. A horizontal film-type cooler: film coefficients of heat transmissions. Industrial & Engineering Chemistry, 1936, 28(5): 537–541

[3] Kocamustafaogulari G, Chen I Y. Falling film heat transfer analysis on a bank of horizontal tube evaporator. AIChE Journal. American Institute of Chemical Engineers, 1988, 34(9): 1539–1549

[4] Rogers J T, Goindi S S. Experimental laminar falling film heat transfer coefficient on a large diameter horizontal tube. Canadian Journal of Chemical Engineering, 1989, 67(4): 560–568

[5] Mitrovic J. Influence of tube spacing and flow rate on heat transfer from a horizontal tube to a falling film. International Heat Transfer Conference San Francisco, 1986, 4: 1949–1956

[6] Mohamed A M I. Flow behavior of liquid falling film on a horizontal rotating tube. Experimental Thermal and Fluid Science, 2007, 31(4): 325–332

[7] Chen C I, Chen C K, Yang Y T. Perturbation analysis to the nonlinear stability characterization of thin condensate falling film on the outer surface of a rotating vertical cylinder. International Journal of Heat and Mass Transfer, 2004, 47(8-9): 1937–1951

[8] Bandelier P. Improvement of multifunctional heat exchangers applied in industrial processes. Applied Thermal Engineering, 1997, 17(8-10): 777–788

[9] Hari S, Takagi T, Tanaka K, Higashiya T. Turbulent heat transfer to the flow in a concerntric annulus with a rotating innner cylinder. Journal of Flow Visualization Society Japan, 1986, 3: 895–901

[10] Hu X, Jacobi A M. The intertube falling film part1-flow characteristics, mode transitions and hysteresis. ASME Journal of Heat Transfer, 1996, 118(3): 616–625

[11] Jafar F, Thorpe G, Turan O F. Liquid film falling on horizontal circular cylinders. 16th Australasian Fluid Mechanics Conference, 2007, 2-7: 1193–1199

[12] Gao D, Morley N B, Dhir V. Numerical simulation of wavy falling film flow using VOF method. Journal of Computational Physics, 2003, 192(2): 624–642

[13] .Gu F, Liu C J, Yuan X G, Yu G C. CFD simulation of liquid film flow on inlined plates. Chemical Engineering & Technology, 2004, 27(10): 1099–1104

[14] Ouldhadda D, Idrissi A I, Asbik M. Heat transfer in non-Newtonion falling liquid film on a horizontal circular cylinder. Heat and Mass Transfer, 2002, 38(7-8): 713–721

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant No. 20976118).

版权

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg