Measurement of thermal diffusivity by propagation of thermal waves: a new modification of the Ångström method

A new technique for measurement of the thermal diffusivity is presented here. The technique is a modification of the well-known Ångström’s method, which relies on the steady-periodic propagation of thermal waves along a specimen to estimate the diffusivity. The novelty of the proposed modification is that harmonic thermal waves with mean value equal to the ambient temperature are induced in the specimen by means of a purposely developed source, based on the Peltier effect. This allows estimating the diffusivity by relatively simple processing of surface-temperature data, acquired by infrared thermography.The mathematical formulation of the thermal problem is described here, together with the experimental procedure and the apparatus by which the most proper thermal signal can be achieved. A cross comparison with other measurement techniques is finally reported.