• Graham, Elizabeth
• Ong, Teng-Cheong

Abstract

There are various methods available to predict the eutectic composition of binary salt systems; however, they do not always yield accurate results, which leads to large discrepancies in the literature and can significantly affect the efficiency of these binary systems during use. In this study, we present an innovative empirical method for accurately identifying the correct eutectic composition, utilizing a Differential Scanning Calorimetry (DSC) technique. The method involves the measurement of the change in the latent heat of fusion of varying ratios of a binary system of interest, with the maximum latent heat corresponding to the ‘true eutectic’ composition. To confirm that the composition identified with this approach is truly eutectic, samples were analysed using Scanning Electron Microscopy (SEM) imaging. The findings of this study are significant because for 4 different binary salt mixtures evaluated, the results showed that previously published eutectic compositions deviate from the true eutectic by as much as 9 wt%. This method is highly pertinent for the application of molten salts in commercial Latent Heat Thermal Energy Storage Systems (LHTESS), because the optimization of the eutectic composition results in a substantial increase in the usable latent heat. This represents a significant savings (as large as a 35 % reduction) in the capital costs of setting up an energy storage system.

Topics

• impedance spectroscopy
• scanning electron microscopy
• differential scanning calorimetry
• heat of fusion