BRANCHING OF TWO-PHASE FLOW FROM A VERTICAL HEADER TO HORIZONTAL PARALLEL CHANNELS

The objective of the present experimental work is to investigate the two-phase flow distribution from a vertical main to parallel horizontal branches. Both the main and the branches have rectangular cross-sections simulating the header and the channels of the compact heat exchangers for air-conditioning systems. The cross section of the main is 8 mm × 8 mm while that of the parallel branches is 8 mm × 1 mm. Here, the second (downstream) junction was taken as the reference. The effect of the distance between the branches was mainly examined by changing it from 9 mm to 49 mm for the given flow conditions at the inlet of the downstream junction. Air and water were used as the test fluids. The superficial velocity ranges of air and water at the test section inlet were 13.2 − 21.4 m/s and 0.08 − 0.28 m/s, respectively. When the branch spacing becomes smaller, the fraction of liquid separation through the downstream branch decreases. The trend remains the same over the entire range of the present experiment, i.e., for different values of quality and the mass flow rate at' the inlet of the downstream junction. Based on the correlation for single T-junctions, a modified correlation was proposed to take into account the effect of the branch distance in predicting the fraction of liquid separation. The correlation represents the experimental results within the accuracy of ± 20 %.