Gas-Solid Interactions Affect the Heat Conduction in Nanoparticle-Based Materials

Owing to their high-specific surface area and low thermal conductivity, nanoporous materials are widely regarded as promising media for adsorbed natural gas (ANG) storage. However, the gas-solid coupling during methane transport within these materials is governed by the coupled effects of temperature and pressure, which traditional theoretical models struggle to accurately quantify. In this work, a multiscale approach is employed. At the nanoscale, molecular dynamics (MD) simulations are performed to quantitatively determine the influence of temperature and pressure on methane adsorption capacity, effective thermal conductivity, and the gas-solid coupling region. Based on these results, a Langmuir adsorption model is refined, and a quantitative correlation for the gas-solid coupling area under varying temperatures and pressures is established. At the macroscale, an effective thermal conductivity predictive model for methane-laden porous media is developed based on established heat transfer theories, incorporating the aforementioned gas-solid coupling effects. Furthermore, by comparing different models, the dominant pressure regimes for distinct coupling mechanisms are clearly identified: at low pressures (P < 2.1 × 10⁵ Pa), heat transfer is dominated by the solid backbone, and the local gas-solid interaction is negligible. Conversely, at high pressures (P > 2.1 × 10⁵ Pa), the local gas-solid interaction becomes a significant mechanism, with its contribution increasing sharply with pressure.