Non-equilibrium thermodynamics approach for the coupled heat and mass transfer of wet mineral porous media in dielectric and magnetic drying

Abstract

A linear non-equilibrium thermodynamics (LNT) microwave-multiphase transport model was developed in order to describe the microwave drying behavior of lignite and hematite thin layer. The moisture ratio profiles and temperature distribution derived in terms of dielectric and coupled dielectric and magnetic loss mechanisms fitted the experimental results well with reasonable deviations. The electric and magnetic field intensities of the corner and edge in the samples were higher than that of the center regions, which met with the experimental temperature distribution. No pumping phenomenon was detected during the whole drying process. The heat flux driven by the polarization relaxation at the higher electric and magnetic field intensities (103–5 × 103 V m−1, 4–7 A m−1) regions was higher than that at the lower ones (2 × 102–2 × 103 V m−1, 1–4 A m−1), and the electric-thermal effects also decreased with the increasing of the sample temperature and the decreasing of the moisture content in the sample.