Macroscopic determination of the heat capacity of residual solid salts for thermal energy storage applications

Abstract

This study determined the heat capacity of residual salts from lithium carbonate production, evaluating their potential for thermal energy storage systems. During experiments, fluctuations in water flow rate required adjustments to maintain safe temperatures, revealing cycles of heat absorption (storage) and release in the salts. These thermal imbalances allowed the measurement of heat capacities in both states: for sample M1, values were 1600 J/kg°C (absorption) and -1404 J/kg°C (release), while for M2, they were 1275 J/kg°C and -1151 J/kg°C, higher than those of substances such as sodium chloride or silica. The salts demonstrated potential for solid-state thermal storage, eliminating the need for pumps and reducing costs in industrial applications. Their reuse also provides environmental and economic benefits by preventing the accumulation of waste in landfills and integrating them into circular economy models. However, further research on other parameters, such as thermal conductivity, is needed to optimise their use. Their implementation would enhance thermal supply continuity, particularly in intermittent solar systems, increasing the renewable share in industrial processes.