Thermal Conductivity Measurement of Molten Salts by the Transient Hot-Wire Method: (1st Report, Construction of probe and preliminary measurement of molten KNO₃)

An apparatus has been cnstructed for precise and absolute measurement of the thermal conductivity of molten salts at high temperatures. The principle of the measurement is based on the absolute transient hot-wire method. In order to apply this method to molten salts, the entire probe has to be insulated. After many trials of insulation techniques applied on probes, it has been confirmed that the following probe is the most suitable for the present purpose: platinum thin wire coated with Si02 prepared by metal alkoxide hydrolysis process, and titanium leads insulated by plasma sprayed Al₂O₃ with SiO₂ upper coating. The usability of the probe has been tested by measuring the thermal conductivity of molten KNO₃in the temperature range from 350 to 390°C. The accuracy of the present measurement is estimated to be ±2%.