A Study of Non-Equilibrium Heat Transfer in Microporous Media

A numerical study of the non-Fourier heat conduction in microporous media is presented. The governing energy equation is formulated based on the two-equation model and the non-Fourier heat conduction model. This formulation leads to the emergence of three thermal lag-times. These parameters account for the thermal interaction between the fluid and neighboring solid matrix as well as the delay time needed for both phases to approach thermal equilibrium. Numerical experiments were conducted for various microporous media to study the thermal non-equilibrium behavior. Results show that the thermal non-equilibrium phenomena have significant effect on the transient response of the porous media only during the early stage of the heating process and in the near-field region where the heat source is located. The thermal responses of the various microporous media were compared to gain understanding of the effect of thermal diffusivity on thermodynamic non-equilibrium phenomena. It was found that the influence of thermal diffusivity is small especially in the near-field (96–200μm). Also, results obtained using the non-Fourier heat conduction model deviates from the predictions based on the classical Fourier model only during the early stage of the heating process. At large time, results obtained from both models are in good agreement.