A new periodic technique for thermal conductivity measurement
Simone Matteï, Eric Tang Kwor
A new measurement technique for thermal conductivity which does not require knowledge of the sample heat capacity and which involves a weak temperature gradient inside the sample is presented. The apparatus is simple: the strip-shaped sample is stuck between two metallic plates, the temperature of one of which is multifrequency modulated. The temperatures of both plates are measured. The ratio of these temperatures is called the transfer function of the sample. The phase of this function is sensitive to the diffusivity and the modulus is sensitive to the conductivity. These parameters can thus be identified by comparison between the measured and the calculated transfer functions. Experiments have been carried out at room temperature on a PVC sample. An exhaustive study of the causes of error has been carried out. The evaluated relative uncertainty on the thermal conductivity is less than 4%. The measured value is consistent with the values found in the literature.