CFD Analysis of Two Phase Flow in a Horizontal Pipe – Prediction of Pressure Drop

Authors: P. Bhramara, V. D. Rao, K. V. Sharma , T. K. K. Reddy

Abstract:

In designing of condensers, the prediction of pressure drop is as important as the prediction of heat transfer coefficient. Modeling of two phase flow, particularly liquid – vapor flow under diabatic conditions inside a horizontal tube using CFD analysis is difficult with the available two phase models in FLUENT due to continuously changing flow patterns. In the present analysis, CFD analysis of two phase flow of refrigerants inside a horizontal tube of inner diameter, 0.0085 m and 1.2 m length is carried out using homogeneous model under adiabatic conditions. The refrigerants considered are R22, R134a and R407C. The analysis is performed at different saturation temperatures and at different flow rates to evaluate the local frictional pressure drop. Using Homogeneous model, average properties are obtained for each of the refrigerants that is considered as single phase pseudo fluid. The so obtained pressure drop data is compared with the separated flow models available in literature.

Keywords: Adiabatic conditions, CFD analysis, Homogeneousmodel and Liquid – Vapor flow.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1333578

References:

[1] John G. Collier, Convective Boiling and Condensation. Mc Graw Hill, 1972. ch.2.
[2] C. Tribbe, H. Muller-Steinhagen, An evaluation of the performance of phenomenological models for predicting pressure gradient during gasliquid flow in horizontal pipelines, Int. J. Multiphase Flow. Vol.26, 2000, pp. 1019-1036.
[3] H. Muller-Steinhagen, K. Heck, A simple friction pressure drop correlation for two-phase flow in pipes, Chem. Eng. Process, vol. 20 , 1986, pp. 297-308.
[4] Engineering Data Book III, Wolverine Tube Inc., Revised in 2006. ch.13.
[5] M.B. Ould-Didi, N. Kattan, J.R. Thome, Prediction of two phase pressure gradients of refrigerants in horizontal tubes, Int. J. Refrigeration. Vol. 25, 2002, pp.935-947.
[6] J. Moreno Quibe'n, J.R. Thome, Flow pattern based two-phase frictional pressure drop model for horizontal tubes, Part I: Diabatic and adiabatic experimental study, Int. J. Heat Fluid Flow, vol.28, Issue. 5,2007, pp. 1049-1059.
[7] J. Moreno Quibe'n, J.R. Thome, Flow pattern based two-phase Frictional pressure drop model for horizontal tubes, part II: New phenomenological model, Int. J. Heat Fluid Flow, vol.28, Issue.5, 2007, pp. 1060-1072.
[8] L. Wojtan, T. Ursenbacher, J.R. Thome, Investigation of flow boiling in horizontal tubes: part I e a new diabatic two phase flow pattern map, Int. J. Heat Mass Transfer. Vol. 48, 2005, pp. 2955-2969.