TEMPERATURE OSCILLATION TECHNIQUES FOR SIMULTANEOUS MEASUREMENT OF THERMAL-DIFFUSIVITY AND CONDUCTIVITY

Simple temperature ocillation techniques are described for the fast measurement of thermal diffusivity and conductivity of liquids. The liquid specimen is a slab bounded above and below by a reference material. Two Peltier elements mounted on the outer surfaces of the reference layers generate temperature ocillations of these surfaces. Temperature waves propagate through the reference layers into the specimen. The thermal diffusivity of the specimen is deduced by measuring and evaluating the amplitude attenuation and/or the phase shift between the fundamental temperature oscillations at the surface of the liquid specimen and at a well-defined position inside the specimen. If the thermal diffusivity of the specimen is known, the thermal conductivity is determined by the measured amplitude attenuation and/or the phase shift between the fundamental temperature oscillations at the surface of the reference layer and at the surface of the specimen. Slab and semi-infinite body geometries are considered. Measurement cells are designed and experiments are carried out with water, ethanol, heptane, nonane, and glycerine. The results of the measurements of thermal diffusivity agree very well, and those of thermal conductivity reasonably well, with the data obtained from the literature.