Pressure Drop And Void Fraction Correlation In An L-shaped Test Facility For Two-phase Flow

Void fraction is an important process variable for volume computation in two phase flow. Inaccurate readings might result in potential loss of revenue and safety. In nuclear industry its importance is augmented due to higher safety concerns.Air-water two phase flows were analyzed experimentally in L-shape facility of inner diameter 40mm for horizontal and vertical upwards flows. Superficial gas and liquid velocities were varied from 0 to 0.1988 m/s and 0.2209 m/s to 0.6629 m/s respectively. Pressure drop results were obtained for bubbly flow and slug flow regimes. A low differential pressure sensor was mounted with a pressure sensing line having pressure tapings spaced 1m apart on the horizontal section of test facility. A pressure sensing line of lm was mounted in the vertical section containing two absolute pressure sensors and a differential pressure sensor for pressure drop measurement.The experimental pressure drop results were validated by comparing them with well accepted correlations of Begg’s& Brill’s and Friedel’s correlation. The experimental pressure drop results were in agreement with Begg’s and Brill’s correlation with an error of ±3%. Void fraction predicted by frictional pressure drop was compared with the actual void fraction of the flow. Accurate measurements are mostly constrained by expensive invasive (optical probes) or non-invasive (x-ray) techniques. This research was focused on the cost effective way of measuring void fraction accurately. The experimental results shows that void fraction can be predicted accurately in the vertical section using absolute pressure sensor while the presence of bubbles causes problems in the readings of differential pressure sensors.