Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Numerical modeling of fluids mixture flow in high velocities with phase change
Submission Author:
Breno de Almeida Avancini , SP
Co-Authors:
Breno de Almeida Avancini, Bruno Carmo
Presenter: Breno de Almeida Avancini
doi://10.26678/ABCM.COBEM2021.COB2021-0224
Abstract
The available methods for gas separation in the market still face important challenges to overcome when costs and efficiency are analysed. The sugar and oil and gas industries raise the demand for new gas separation technologies due to the increase of the production of biogas and the exploration of the pre-salt reservoirs where the gases have a high concentration of carbon dioxide. For this reason, we investigate the feasibility of using supersonic gas separators, which are cryogenic separation devices, to remove part of the carbon dioxide content from raw natural gas and biogas. In that context, we have developed a model of the fluid flow behaviour in a nozzle which allows the verification of the supersonic nozzle separator performance in the component separation of fuel gases that contain high amounts of carbon dioxide and methane. The proposed model assumes inviscid one-dimensional compressible flow of a gas mixture with the presence of the homogeneous nucleation phenomenon. We formulated a differential partial equation solver of the set of equations that model the flow based on the AUSM scheme. We predicted the thermodynamic and physical properties of the fluids using expressions that consider the nonidealities of the fluid behaviour and non-equilibrium states, such as metastability, and are readily available in computational libraries. First, validations of the numeric model were carried out, through the comparison of simulation results with experimental data of supersonic wet steam flows found in the literature. Next, we have produced a numerical model of the flow of methane and carbon dioxide mixtures at supersonic speeds in nozzles. In the simulations performed, the mixture reached conditions in which the carbon dioxide condensed while methane remained gaseous. With the simulation results, we analysed the impact of the nucleation phenomenon in the flow and could assess the sensitivity of the nucleation behaviour to variations of the flow parameters, such as pressure, temperature, and carbon dioxide concentration at the inlet. These results constitute a first analysis of the purification capacity of the supersonic gas separator by the condensation of carbon dioxide.
Keywords
Supersonic Flow, Nucleation, Compressible flow, multiphase flow
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