Fundamental Analysis on the Heat Transfer of the Double Hot Thermocouple for the Measurement of Thermal Diffusivity of Molten Slag

摘要

New method to measure the thermal diffusivity using double hot thermocouple technique (DHTT) was developed. The factors affecting on the thermal diffusivity measurement were elucidated. The finite pulse-time effect and the heat loss were quite different from that of laser pulse method and it was found that the analytical method could not used for the DHTT. Then, numerical method was applied to analyze the heat conduction on the DHTT. The results obtained are as follows: The heat loss in DHTT was quite high and the analytical method presented by Heckman could not apply. In addition , since the shape and duration of pulse in the heat source was entirely different from the laser flash method,, the numerical method was useful to simulated the heat transfer on the DHTT. The new relationship between the thermal diffusivity a and the time at the half-maximum temperature t_(05) was obtained using the numerical method, which was in excellent agreement with the observation. alpha(X 10~4m~2/s) = 0.000707(t_(0.5)_/t_p )~(-1.8946)