Measurement of Thermal Diffusivity at Continuous Heating Rate: Periodic heating method

In this paper, a new modified periodic heating method in which periodical heating of the specimen is overlaid with continuous heating is proposed. It permits easy measurement of the temperature dependence of thermal diffusivity. Measurements are made for polytetrafluoroethylene and a packed bed of aluminum oxide at a heating rate of 0~0.05 K/s from 380 K to 800 K. The observed value for polytetrafluoroethylene is 0.88 × 10-7 m2/s at 380 K and 0.65 × 10-7 m2/s at 550 K. The effective thermal diffusivity of the packed bed of aluminum oxide (apparent density, 8.5 x 102 kg/m3) is approximately 2,05×l0-7m2/s between 500 K and 800 K. These results are independent of heating rate, period of heating and radius of specimen.