Numerical modeling of high-speed flows of fluid mixtures with phase change through nozzles

Autor(es)

de Almeida Avancini, Breno ; Carmo, Bruno Souza

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY; v. 149, n. 1, p. 13-pg., 2023-11-23.

Resumo

The oil and gas industry raises the demand for new gas separation technologies due to the exploration of pre-salt reservoirs where natural gas typically has a high concentration of carbon dioxide. The sugar and ethanol industry also contributes to this demand with the increase in the production of biogas from vinasse, which also has a high CO2 content. For this reason, we investigate the feasibility of using supersonic gas separators to remove part of the carbon dioxide content from raw natural gas and biogas. In this context, we have developed a model of the fluid flow behavior in a nozzle which allows the verification of the performance of the device in the condensation of carbon dioxide from fuel gases. The proposed model assumes inviscid, one-dimensional, multiphase, compressible flow of a gas mixture with homogeneous nucleation and growth of CO2 droplets. We implemented a solver in python programming language, based on the AUSMDV scheme. We predicted the thermodynamic and physical properties of the fluids using expressions that consider non-ideal fluid behavior and non-equilibrium states, such as metastability, and are readily available in computational libraries. First, validations of the numerical model were carried out through the comparison of simulation results with experimental data of supersonic wet steam flows found in the literature. Next, we carried out simulations for CO2 and air-CO2 mixtures and also compared with available experimental results. Subsequently, 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 the methane remained gaseous. We analyzed the impact of the nucleation phenomenon in the flow and could assess the sensitivity of the nucleation behavior to variations of some flow parameters, such as total pressure, total temperature, and carbon dioxide concentration at the inlet, and nozzle geometry parameters. We verified that the proposed model could predict the pressure fluid of a multicomponent gas expansion through a supersonic nozzle with condensation with less than 8% of error. We also verified that within the proposed boundary conditions for the biogas expansion, more than one expansion would be needed to meet regulatory requirements of concentration of CH4 as there was a limit of concentration variation given by the boundary conditions applied to the nozzle. We also identified that for the set of proposed parameters, the ratio between the nozzle throat and outlet areas was the parameter to which the capacity of the nozzle of increasing the concentration of methane presented the highest sensitivity. (AU)

• Processo FAPESP: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Beneficiário: Julio Romano Meneghini
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia
• Processo FAPESP: 20/15230-5 - Centro de Pesquisa e Inovação de Gases de Efeito Estufa - RCG2I
• Beneficiário: Julio Romano Meneghini
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia