ABSTRACT
Recently, there has been a noticeable increase in the applications of composite mixtures containing molten salt and solid oxide for thermal energy conversion and storage systems. This highlights that thermal conductivity of the composites are central for the purpose of designing and devising processes. Measuring the thermal conductivity of molten samples at elevated temperatures remains challenging. In this study, the possibility to use heat flux differential scanning calorimetry (DSC) to measure the thermal conductivity of molten samples at elevated temperatures is reported for the first time. The thermal conductivity of composite mixtures containing eutectic (Li,Na)2CO3 with and without selected solid oxides at ~675 °C was determined by using the proposed DSC approach. This mixture is a candidate for high temperature waste heat conversion to electric energy. In the DSC measurement program, steps with repeated thermal cycles between 410 and 515 °C were included to limit the effect of the interface thermal contact resistance. The determined values 0.826 ± 0.001, and 0.077 ± 0.004 W m-1K-1 for the carbonate mixtures with and without solid MgO were found to match the reliable analysis at similar conditions.
ABSTRACT
Industrial primary production of aluminium has been developed and improved over more than 100 years. The molten salt electrolysis process is still suffering from low energy efficiency and considerable emissions of greenhouse gases (CO2 and PFC). A new concept has been suggested where methane is supplied through the anode so that the CO2 emissions may be reduced significantly, the PFC emissions may be eliminated and the energy consumption may decrease significantly. Porous carbon anodes made from different graphite grades were studied in controlled laboratory experiments. The anode potential, the anode carbon consumption and the level of HF gas above the electrolyte were measured during electrolysis. In some cases it was found that the methane oxidation was effectively participating in the anode process.
