Análise Numérica de Escoamento de Emulsão Através de Restrições

Abstract

It is indispensable to understand the behavior of drops and bubbles breakup in multiphase flows for many industrial applications. In the oil industry, for example, the droplet breakup during the oil extraction process directly impacts the separation of components extracted from the well. It is known that the separation efficiency between oil and water depends on the droplet size distribution: the smaller the drops, the lower the separation efficiency. The separation between oil and water must be effective due to the need to have a pure oil, without the presence of water, and due to Federal Law 9.966/2000. To achieve that, separation techniques and ways to prevent droplet breakage have been studied. The breakage and coalescence of droplets present in emulsions has been studied experimentally and numerically. In this context, this work develops numerical analyses to evaluate the flow of emulsions through different restrictions. For this, the ANSYS Fluent 2020 R2 software associated with the Euler- Lagrange approach and the Stochastic Secondary Droplet Model is used. A technique is developed to define critical Weber and break constant values. Thus, the break model can be configured without the need to obtain experimental data. In order to validate the computational modeling and the technique developed to configure the break model, two experimental literature works are used. These works analyze the flow of oil-in-water emulsion through different restrictions with Reynolds values between 28,000 and 69,000. The relative deviations obtained in diameters greater than are less than 10%. After validations, this work investigates the influence of turbulent kinetic energy dissipation rate on droplet breaking. It is observed that the integral of the average kinetic energy dissipation is the most adequate variable to suggest whether a restriction breaks more or less drops. Finally, new restrictions geometries are analyzed. These are: straight restriction, round restriction, nine hole restriction and chamfered restriction. These restrictions are subjected to an emulsion flow with a Reynolds number equal to 41,000. Among the analyzed restrictions, the round restriction achieves the best performance, presenting a value of 196% higher, when compared to the straight restriction.