Identification by thermal impedance: application to wet materials

This work introduces a thermal impedance application to the thermophysical characterisation of a porous material with different water contents. The object of the study is to monitor the thermal effusivity of a foundry sand as a function of its water content. Two methods of treatment are developed. The first one is based on a no-parameter study to estimate impedance starting from the Fourier transform of the signals. In order to address the specific problem of an evolving medium, a second method based on a synthesis of the numerical filters resulting from the z transform theory was examined. This method enables a significant reduction to be made in measurement time. The results obtained in this way are compared with those from two traditional methods of conductivity and specific heat measurement, which are adopted as means of validation.