The influence of macropores on the thermal state of soil during infiltration in the absence of thermal equilibrium

Macropores influence water and heat transfer in heterogeneous soils, but their thermal effects under local thermal non-equilibrium(LTNE) conditions remain underexplored. This study presents a dual-permeability heat transport model that captures phase-specific temperatures for water, air, and the solid matrix in both macropores and micropores. The model accounts for conduction, advection, and inter-domain heat and mass exchange. We validate the model against laboratory infiltration experiments under controlled thermal boundary conditions, with and without engineered macropores. Simulations reproduce key observations, including thermal gradients at the wetting front in macropores and smoother profiles in micropores. The results show that the water and gas in the macropores can maintain temperature differences of 2–5 for up to 3–5 h during infiltration, while the micropore domain equilibrates in less than 1 h. Sensitivity analysis indicates that the mass exchange coefficient ( s −1 ) and the macropore volume fraction ( ) control the rate and extent of thermal equilibration. While the macropore domain exhibits advection-dominated and spatially variable temperatures, the micropore domain responds more gradually to temperature changes and rapidly reaches equilibrium among its phases. These insights provide a foundation for developing computationally efficient models of heat transfer during infiltration in strongly heterogeneous soils.