A Non-Contact Measurement of Thermal Conductivity and Diffusivity of Anisotropic Materials

The purpose of this paper is to develop a non-contact method for simultaneous measurement of thermal conductivity and diffusivity of anisotropic materials. This method could be applied to biological materials. Three-dimensional transient heat conduction equation in an anisotropic solid is solved numerically when the solid surface is heated locally. Then, the time variations of non-dimensional average surface temperature are obtained as a master plot, which depend on the ratio of thermal conductivities in x-, y-direction E_<xy>(=λ_y/λ_x). In experiment, the surface of an anisotropic sample is heated locally by the laser beam and the surface temperature profiles are measured by an infrared thermometer. The measured temperature variations are compared with the numerical ones to yield the thermal conductivity and diffusivity in x-direction λ_x, α_x and the ratio E_<xy> simultaneously. To confirm the applicability and the accuracy of the present measuring method, are used the multi-layered paper and vinyl chloride resin film as the samples with known thermophysical properties. It is found that the method could obtain the thermal conductivity, diffusivity and anisotropic ratio (E_<xy>) within errors of 6%, 25% and 4%, respectively, when the errors of measured laser output, heating radius and temperature are assumed to be within 2%, 3% and 0.2K, respectively