(An) experimental study on two-phase flow distribution at header-channel junctions

Abstract

An experimental study has been conducted to examine the flow distribution of two-phase mixture in small-scale header-channels assembly. As a fundamental approach, prediction models, originally developed for large T -junctions, were assessed based on the experimental results. Among the prediction models for T -junction flows, the model by Hwang et al. (1988) was concluded to be the most appropriate. As for the effect of the flow interaction between two neighboring branches, the liquid flow rate (and hence, the total flow rate) through the downstream branch becomes smaller with the smaller branch distance. A correlation for the liquid dividing line was proposed to take account of the effect of the ``branch distance in predicting the liquid separation fraction within the accuracy of ?15% by modifying the model of Hwang et al. (1988). The distribution pattern of the flow to the channels was determined by the flow recirculation occurred near the end plate of the header. The header flow consists of three zones, namely, regions A, B and C, regardless of inlet flow rate of the liquid and the gas. In the entrance region of the header (region A), less amount of the liquid was separated out through the channels as the two-phase mixture proceeded in the downstream direction. At the immediate upstream of the end plate (region C), the amount of the liquid separation also decreased as approaching the end plate but gradually due to the flow recirculation. In between those regions (i.e., in region B), the liquid separation rate increased along the downstream direction because of the interaction between the reverse flow (by the flow recirculation in region C) and the forward flow (in region A). For the gas flow distribution, the trend appeared opposite to the liquid case throughout the header section, but the variation was relatively small. The rate of the liquid flow separation to the channels near the entrance of the header (i.e., region A) was well predicted by the modified m...