Foued Mzali

Inverse problem in a porous medium: estimation of effective thermal properties

A numerical inverse analysis is presented to simultaneously estimate the effective thermal conductivity, the effective volumetric heat capacity as well as the heat transfer coefficient between a porous medium and a hot wire. The direct problem simulates numerically the hot wire technique considering a porous medium sample. The measured temperature data are generated by adding random errors to the simulated temperatures. An iterative procedure, based on minimizing a sum of squares function with the Levenberg–Marquardt method, is used to solve the inverse problem.

Optimal experiment design for the identification of thermo-physical properties of orthotropic solids

This numerical study deals with the identification of several thermal properties of orthotropic solids by using an optimal experimental design. The system under investigation is a cylindrical vertical sample, which is submitted to an irradiation flux on the upper face on a central circular area. The temperature response, during and after the irradiation, is measured at the opposite face. In this article, the system is particularly developed to the identification of the Fourier number including the axial diffusivity, the ratio of radial to axial conductivities, a Biot number and a heat flux term from one temperature evolution versus time. The temperature sensor position is adjusted simultaneously with the identification of the above four parameters.

Optimal experiment design and thermo-physical characterization of a plastically deformed solid

The thermo-physical properties of a plastically deformed solid are measured using a non-destructive photo-thermal method. The experiment is optimally designed in order to choose the optimal heat flux duration, the sample thickness and the thermocouple position. The thermo-physical properties of the deformed sample are then identified by minimizing the sum of squares of the differences between experimental measurements and numerical results of a 2D model describing the heat transfer in the cylindrical sample. These identification results are finally compared with standard thermal diffusivity measurements (isotropic model) made on both initial and deformed samples.

Analysis of differential scanning calorimetry data of the paraffin/graphite waste composites for thermal energy storage

A paraffin/graphite waste composite for thermal energy storage at low temperature was elaborated using the cold uni-axial compression technique and its thermal energy storage properties were studied versus percentage of graphite waste using differential scanning calorimetry (DSC). Results indicated that the phase transition temperature did not change with a change in the amount of paraffin, whereas the latent heat of phase change was decreased with increasing graphite waste content. Also, the effect of the graphite addition on the thermal conductivity of the composites was investigated using the periodic temperature method.