Date of Award
Doctor of Philosophy (PhD)
Dr. M. Shoukri
Phase redistribution is a complicated physical phenomenon which occurs in dividing two-phase flow in T-junctions. In this study detailed experimental data of phase redistribution and associated pressure changes in T-junctions having horizontal inlet are presented for both annular and stratified inlet flows. Two phenomenological phase redistribution models for annular and stratified flows were developed. The objectives of the study are enriching the available data bank on the subject through the experimental measurements and enhancing current understanding of the phenomenon through model development and analysis.
Two-phase redistribution in T-junctions was found to be significantly affected by the inlet flow conditions, i.e. inlet flow pattern, inlet quality and inlet flow rates. The phase redistribution phenomenon also depends on the junction geometry, i.e. branch orientation and diameter. The experimental results showed that for annular flow in horizontal T-junctions an increase of inlet quality reduces the degree of phase redistribution while the inlet mass flux was found to be less significant. However, in stratified flow the increase of either the inlet superficial vapour or liquid velocities increases the degree of phase separation. The experimental results also showed that decreasing the branch diameter will increase the degree of phase separation. Moreover, downward orientation of the branch can reduce the branch flow quality significantly.
The pressure changes in T-junctions were correlated using simple momentum and energy balances for the run and branch respectively using measured void fractions. The run momentum correction factor was found to be independent of inlet flow conditions but was dependent on the junction geometry. The branch two-phase multiplier was found to depend on both the inlet flow conditions and junction geometry. Comparison of the present data on pressure changes in T-junctions with some available models showed that those models which account for phase redistribution effects were better than the others in correlating the present data, confirming the strong interdependence between the pressure changes and phase redistribution.
A general phenomenological phase redistribution model was derived based on the analysis of available models. This general model was extended to two phenomenological models for annular flow and stratified inlet flows. Each of the models included two submodels to account for two phase distribution in the inlet tube and phase redistribution in the junction. Comparisons of the present experimental data and some available models were made and the results indicate that most of the available models can predict 70% of annular flow data and 80%of stratified flow data within +40%of the measurements. The newly developed models in this study can predict 90% of the data within +40% for both annular and stratified flows.
Peng, Fei, "A Study of Dividing Steam-Water Flow In T-Junctions: Experiments and Analyses" (1994). Open Access Dissertations and Theses. Paper 2276.