Gas/shear-thinning liquid flows through pipes: Modeling and experiments

• A model for gas/power-law fluid slug flow was presented and validated.
• Flow pattern maps of gas/shear thinning fluid flows were studied.
• The existence region of stratified flow was well predicted by the ZRC criteria.
• Slug velocity, slug frequency, and slug lengths were measured.
• A correlation for the frequency of gas/shear-thinning fluid slug flow was proposed.

In chemical and oil industry gas/shear-thinning liquid two-phase flows are frequently encountered. In this work, we investigate experimentally the flow characteristics of air/shear-thinning liquid systems in horizontal and slightly inclined smooth pipes. The experiments are performed in a 9-m-long glass pipe using air and three different carboxymethyl cellulose (CMC) solutions as test fluids. Flow pattern maps are built by visual observation using a high-speed camera. The observed flow patterns are stratified, plug, and slug flow. The effects of the pipe inclination and the rheology of the shear-thinning fluid in terms of flow pattern maps are presented. The predicted existence region of the stratified flow regime is compared with the experimental observation showing a good agreement. A mechanistic model valid for air/power-law slug flow is proposed and model predictions are compared to the experimental data showing a good agreement. Slug flow characteristics are investigated by the analysis of the signals of a capacitance probe: slug velocity, slug frequency, and slug lengths are measured. A new correlation for the slug frequency is proposed and the results are promising.