A new model for the non-steady-state probe method to measure thermal properties of porous media

Abstract

The starting point is the modified Jaeger model. This cylindrical model takes into account the major properties of the probe, the thermal conductivity and the heat capacity of the medium and the contact resistance between the probe and the medium. Because the mathematical description results in non-linear functions of these three thermal parameters, the Gauss-Newton iteration method is used. To obtain a better description of the measurement for small time values, a second-order time correction is added. The experimental test results in an inaccuracy of 0.5–2% for the thermal conductivity, while the two other parameters are accurate to within 5–15%.