GeoChemFoam: Direct Modelling of flow and heat transfer in micro-CT images of porous media

TL;DR

GeoChemFoam introduces a novel numerical model for simulating conjugate heat transfer in porous media micro-CT images, enabling detailed analysis of flow and heat transfer processes in complex geological structures.

Contribution

The paper presents a new micro-continuum based numerical model for conjugate heat transfer in porous media, validated against standard methods and applied to geothermal and heat exchanger simulations.

Findings

Validated model against standard two-medium approach.

Simulated heat transfer in geothermal reservoir analogs.

Performed sensitivity analysis in porous heat exchangers.

Abstract

GeoChemFoam is an open-source OpenFOAM-based numerical modelling toolbox that includes a range of custom packages to solve complex flow processes including multiphase transport with interface transfer, single-phase flow in multiscale porous media, and reactive transport with mineral dissolution. In this paper, we present GeoChemFoam's novel numerical model for simulation of conjugate heat transfer in micro-CT images of porous media. GeoChemFoam uses the micro-continuum approach to describe the fluid-solid interface using the volume fraction of fluid and solid in each computational cell. The velocity field is solved using Brinkman's equation with permeability calculated using the Kozeny-Carman equation which results in a near-zero permeability in the solid phase. Conjugate heat transfer is then solved with heat convection where the velocity is non-zero, and the thermal conductivity is calculated as the harmonic average of phase conductivity weighted by the phase volume fraction. Our model is validated by comparison with the standard two-medium approach for a simple 2D geometry. We then simulate conjugate heat transfer and calculate heat transfer coefficients for different flow regimes and injected fluid analogous to injection into a geothermal reservoir in a micro-CT image of Bentheimer sandstone and perform a sensitivity analysis in a porous heat exchanger with a random sphere packing.