FLOW PATTERN, PRESSURE DROP, AND VOID FRACTUION IN VERTICAL TWO COMPONENT TWO-PHASE PIPE FLOW

Abstract

Two-phase flow pattern, pressure drop, and void fraction in vertical transparent pipe of 0.0254 m internal diameter and 3.65 m length is investigated experimentally. The rig is designed to achieve the measurements of pressure drop and void fraction for different combinations of phase superficial velocities such that the regimes encountered are bubbly, slug and annular, which required a wide range of water and air superficial velocities. The flow patterns are investigated by recording video movies for each test achieved. The pressure is measured by using five pressure sensors distributed through the pipe, while the void fraction values are measured by using two quick closing valves at pipe terminals. The effect of heating liquid to 60C˚on the pressure drop values is also discussed. The results are compared with many pressure drop and void fraction correlations. The pressure drop results in bubbly flow regime are nearest to the Lockhart and Martinelli correlation with an average difference of 3.93 %., while in slug and annular flow regimes the results are well predicted by Steinhagen and Heck correlation with an average difference of 18.4 % and 26%. Hughmark correlation is the nearest to the void fraction results in bubbly flow regime with an average difference of 2.4% ,while Chisholm and Smith correlations are the best in slug and annular flow regimes with an average difference of 6.91% and 1.71% respectively.