A comprehensive model for stability of dispersed oil-water flow in horizontal and inclined pipes

•A mechanistic model for stability of liquid-liquid flow in pipes is proposed.•It accounts for break-up, sedimentation, dispersion and accumulation of droplets.•Droplet coalescence and segregation are considered by attaining critical accumulation.•Critical droplet accumulation is associated to the phase inversion point.•Model predictions agree well with numerous sets of experimental data. Prediction of dispersed flow regimes in liquid-liquid pipe flow is of great importance for many industrial processes. This work proposes a mechanistic model to determine the stability bounds of dispersed liquid-liquid flow patterns that presents significant improvements compared to other classical criteria. The model accounts for turbulent break-up of dispersed phase droplets, sedimentation, dispersion, and accumulation of droplets. In addition, droplet coalescence and segregation are considered by means of attaining critical concentrations that can be associated with the phase inversion point of the liquid-liquid mixture. Modeled bounds are compared with available experimental data, showing good agreement in flows of mineral oil and water, as well as flows of crude oil and water. Moreover, the model is more accurate and descriptive than other predictions from commonly used criteria. The effect of fluid properties, flow rates, and pipe geometry are discussed. Limitations and possible refinements of the suggested model are also treated.