Measurements of Thermal Conductivity and Thermal Diffusivity of Molten Carbonates

概要

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The thermal conductivity and thermal diffusivity of molten carbonates (Li_2CO_3/K_2CO_3 and Li_2CO_3/Na_2CO_3) were measured using the transient short-hot-wire method in the temperature range from 530 to 670℃. Two types of probes were examined. One was a platinum short-hot-wire probe coated with alumina (Al_2O_3) thin film to prevent current leakage and corrosion. The other was a bare gold short-hot-wire probe. For the platinum probe, the quality of coating reduces gradually during the measurements of molten carbonates due to their high corrosiveness. The quality reduction has caused relatively large errors of measured thermal conductivity and thermal diffusivity around ±10 and ±40%, respectively. For the bare gold probe, the corrosion due to electro-chemical reaction can be neglected and the effect of current leakage into the molten carbonates can be estimated. Then the temperature dependency of the electrical resistivity was calibrated accurately and compared with existing data. By using this gold probe without coating on the hot wire surface, the thermal conductivity and thermal difrusivity of molten carbonates can be measured within errors of ±3 and ±9%, respectively. It is further confirmed that the gold probe can be used repeatedly without the reduction of quality.
2001-12-14