Tingting Yu

Modeling of Gas-liquid Flow in an Upward Vertical Annulus

Upward vertical two-phase flow in annuli was previously studies in TUFFP experimentally and theoretically by Caetano (1986). A mechanistic model was proposed. In light of the new developments in mechanistic modeling, multiphase flow in annuli has been re-investigated.

A new mechanistic model has been developed to predict liquid holdup, pressure gradient and the flow pattern transition. The unified model idea was successfully applied in the modeling of annulus. Caetano’s (1986) experimental data were used to evaluate the mechanistic and flow pattern transition models and the results are compared with the modified unified model results. The comparison shows that the predictions from the flow pattern transition models agree well with the experimental observations. For the hydrodynamic model, the average absolute errors for pressure gradient and liquid holdup predictions are within 10% for slug flow and churn flow. However, these errors become larger for annular flow. The results are analyzed to identify the reasons for the large errors in annular flow. A further study is recommended to improve the annular flow model.

A preliminary code is already been written for the model. Currently, the model is being analyzed by comparing the results obtained by the code with the already present experimental data from previous TUFFP studies. After that, all necessary changes will be made in the code or model for better predictions.