Lattice Boltzmann simulation of near/supercritical CO2 flow featuring a crossover formulation of the equation of state

• Published in: Computers & fluids 2021-02, Vol.216, p.104820, Article 104820
• Main Authors: Kabdenova (Dauyeshova), Bagdagul, Rojas-Solórzano, Luis R., Monaco, Ernesto
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbon sequestration; Computational fluid dynamics; Critical flow; Critical point; Cubic equations; Droplets; Equation of state; Equations of state; Fluid flow; Ideal gas; Lattice Boltzmann Model; Liquid-vapor equilibrium; Model accuracy; Modelling; Multiphase; multiphase flows; Numerical prediction; Porous media; Pseudopotential model; Qualitative analysis; Scaling laws; Supercritical fluids; Switches; Thermodynamic properties; Two dimensional models; Two phase flow; Water drops; Working fluids
• ISSN: 0045-7930; 1879-0747
• DOI: 10.1016/j.compfluid.2020.104820

•Crossover Peng-Robinson Eos is incorporated into pseudopotential multiphase LBM.•Crossover EoS is a hybrid equation which uses non-analytic scaling laws close to critical region where it is valid.•LBM with crossover P-R EoS is evaluated for CO2 flows in the critical regions.•LBM with crossover P-R EoS predicts the behavior of fluids with higher accuracy in near-critical and supercritical regions. In this work, we have incorporated a crossover equation of state into the pseudopotential multiphase Lattice Boltzmann Model (LBM) to improve the prediction of thermodynamic properties of fluids and their flow in near-critical and supercritical regions. Modeling carbon dioxide (CO2) properties in these regions is of increasing interest for industrial processes such as CO2 storage and heat transfer where CO2 is used as a working fluid. Despite the importance of accurately modeling near-critical and supercritical fluids, popular classical cubic equations of state (EoS) are not accurate. The proposed crossover EoS is a proven hybrid equation which uses the original classical EoS far from the critical point where it is valid, and near the critical point, it asymptotically switches to using non-analytic scaling laws. It also transforms into the ideal gas EoS as the density approaches zero. In order to demonstrate the validity and versatility of the crossover approach in the prediction accuracy of LBM in near-critical flows, this formulation was incorporated into the Peng-Robinson (P-R) EoS. First, 2D static droplets of CO2 and water at vapor-liquid equilibrium were modeled using both P-R EoS and its crossover formulation, and the numerically predicted results were then compared against the experimental data. The results demonstrate that the model accuracy in representing the thermodynamic behavior of the fluid in near-critical region is improved after adopting the crossover formulation with respect to the classical analytical EoS. The crossover P-R EoS was further applied to study several two-phase CO2 flows in mini-channels at near-critical temperatures. The flow patterns showed a good qualitative agreement with the experimental data in the near-critical region. The study is further extended to multi-component multiphase systems, specifically to water droplet penetration into porous media filled with CO2.