Thermal characterization of poorly conducting solids by the flash method

Estimation of the thermal diffusivity of a poorly conducting solid placed between two metallic layers by the flash method is described. The method consists of applying a brief heat pulse to the front face of the three-layer composite and measuring the temperature rise versus time of the rear face. The thermal contact resistance between the layers and the heat transfer coefficient are obtained simultaneously with the thermal diffusivity of the poorly conducting solid. These parameters are identified by minimisation of the least-squares function comparing the measured and the calculated temperatures. Three models are developed using the thermal quadrupole method. An optimal design of the experiment is also presented and the choice of thermal model for parameter estimation is discussed. The experimental results are in good agreement with the theoretical analysis.