Simultaneous measurement of thermal conductivity and diffusivity by periodic heating of a hot wire

A new unsteady method is proposed to measure simultaneously thermal conductivity and diffusivity, based on the analytical solution for an infinite hollow cylindrical system where a sinusoidal heat flux originates from a wire in the center. The method can also be improved to measure easily the temperature dependencies of the thermal properties under the continuous heating process. Measurement errors due to the finite specimen size and displacement of measurement position are estimated numerically. It is found that the specimen radius size should be three times the distance between central heat source and measurement position. Displacement of measurement position has little effect on the measured value of thermal conductivity. Measurement is carried out for a packed bed of aluminum oxide particles in the temperature range from 350 K to 650 K at a rate of 3 K/min. The measured results agree well with those reported in previous work using the hot-wire method and periodic-heating method.