In-plane Thermal Diffusivity Measurement of Thin Samples Using a Transient Fin Model and Infrared Thermography

Abstract

A method for determining the in-plane thermal diffusivity of planar samples was constructed. The time-dependent temperature field of the sample heated at one edge was measured with an infrared camera. The temperature fields were averaged for different times over a narrow strip around the center line of the sample, and the temperature profiles for varying time were fitted by a solution to a corresponding one-dimensional heat equation. Heat losses by convective and radiative heat transfer were both included in the model. Two fitting parameters, the thermal diffusivity and the effective heat-loss term, were obtained from time-dependent temperature data by optimization. The ratio of these two parameters was also extracted from the steadystate temperature profile. The method was found to give good and consistent results when tested on copper and aluminum samples.

Dependence of thermal conductivity on structural parameters in porous samples

“…10 We thus restricted our consideration to a narrow strip around the center line of the sample plate and used a one-dimensional heat equation to describe the system,…”

“…To this end we have previously described a method by which the in-plane heat diffusivity of planar samples could be determined. 10 In this method the sample was heated at one edge and the induced transient temperature field was measured with an infrared camera. The a lasse.miettinen@jyu.fi 2158-3226/2012/2(1)/012101/15 C Author(s) 2012 2, 012101-1 recorded data were fitted by the solution of a one-dimensional transient fin model, thermal diffusivity and a heat-loss coefficient as the two fitting parameters.…”

Measurement of the In-plane Thermal Diffusivity and Temperature-Dependent Convection Coefficient Using a Transient Fin Model and Infrared Thermography

“…There are also other methods that utilize infrared thermography, but the heating of the sample is done differently than in the flash method [4,5]. The convective heat transfer from the sample is taken into account in the latter two methods, and the related heat-transfer coefficient can be determined simultaneously with the thermal-diffusion coefficient.…”

“…We referred above to a method that we have previously introduced for determining the in-plane thermal-diffusion coefficient in planar geometry [5]. The method was based on heating a thin planar sample at one end and measuring both the transient and stationary temperature fields in the sample using an IR camera, while introducing at the same time a weak forced flow of air around the sample to stabilize the convective heat transfer from it (see Fig.…”

“…It had been assumed in the model that the heat transfer by convection would be constant in the direction in which the temperature profile was averaged. Now that air was flowing parallel to the gradient of the temperature profile, this assumption was no longer valid: the velocity and thermal boundary layers were The principle of our previous experimental method for determining the in-plane thermal diffusivity [5]. The planar sample was heated at one edge while a slow air flow was introduced around the plate.…”