Research Project AX5

Non-isothermal heat transfer processes in coupled free-flow and porous-media systems find relevance in various environmental and technical applications. These include geothermal energy systems, turbine cooling, and evaporation from soil. For modeling transport processes in porous media, local thermal equilibrium is often assumed. However, the assumption of instantaneous heat transfer between different phases may not always be valid, especially for systems with high temperature gradients or large differences in thermal conductivities between distinct phases.

In this project, existing local thermal non-equilibrium (LTNE) models at the pore- and REV-scale are extended for multi-phase and interface-driven processes. Hereby, the effect of LTNE in the porous medium is studied to gain insights into the magnitude and relevance of taking different temperatures of distinct phases into account. For detailed investigations at the pore-scale, a dual-network model in the porous medium is considered. Through up-scaling, effective parameters needed for the coupled REV-scale model are obtained, such that the assumption of the LTNE can be investigated at larger, averaged scales.