科研之友
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摘要
The parallel hot wire technique has been widely used to measure the thermal conductivity of refractories. In this study, a non-linear fitting procedure based on the line heat source model (ideal model) is developed to obtain the thermal conductivity and thermal diffusivity of a sample from the measured temperature curve, whose accuracy is influenced by several factors. A semi-analytical method is proposed to evaluate the temperature change in the sample in parallel hot wire set-ups, considering the effects of the radii of the hot wire and thermocouple with their layers, their heat capacities and thermal contact resistances, and the outer boundary of the sample. The influence of these factors is analysed through comparisons of the temperatures calculated with the semi-analytical model and the line heat source model. Virtual measurements for samples with different thermal conductivities and thermal diffusivities in a parallel hot wire set-up are generated by the semi-analytical method. By fitting these virtual temperature curves with the line heat source model, it is found that the errors in the fitting results depend strongly on the length and position of the selected fitting time interval, and samples with high thermal conductivities and thermal diffusivities tend to exhibit larger errors. This study provides an efficient method to analyse the errors in line heat source fits for parallel transient hot wire measurements.
- 出版日期2019-2-1
- 单位清华大学
