Numerical analysis of liquid-gas phase transition effects on pore clogging and particle transport

Abstract

This study investigates the impact of liquid–gas phase transition on pore clogging during supercritical carbon dioxide (SC-CO<inf>2</inf>) geological storage. To address this, we developed a pore-scale CFD-DEM-VOF model incorporating phase transition. It is capable of simulating phase transition processes in multiphase flows and their subsequent effects on particle behavior, as well as the resulting coupled dynamics of particle transport, pore clogging, and unclogging. Throughout these simulations, drag forces, contact forces on particles, and the evolution of the flow field were meticulously tracked and analyzed. Crucially, the research employed both constant-velocity and constant-pressure inlet boundary conditions, using non-phase-transition models as controls for comparison. Analysis of the results revealed that phase transition influences particle behavior through two distinct mechanisms. Firstly, volume expansion accelerates particle transport towards pore outlets. Conversely, and simultaneously, phase transition enhances turbulence and vortex formation within the flow field. This secondary effect loosens particle clusters, slows their movement, and traps particles within swirling flow structures that impede passage. Under constant-velocity boundary conditions, higher phase transition rates generally promote faster particle transport through pores. In contrast, under constant-pressure conditions, phase transition reduces the inlet flow velocity at higher rates. Due to the low viscosity and density of gas, it is less effective at carrying particles through pores under these conditions. As a result, moderate phase transition rates yield the highest particle transport rates in the constant-pressure inlet model.