Thermodynamic modeling and experimental verification of new eutectic salt mixtures as thermal energy storage materials

摘要

In this work, modified BET model was applied to obtain phase diagrams and to design new eutectic mixtures. As a result, the eutectic composition and the melting point of two mixtures based on salt hydrates: LiNO3 center dot 3H(2)O-NaNO3-Mn(NO3)(2)center dot 6H(2)O and LiNO3 center dot 3H(2)O-Mn(NO3)(2)center dot 6H(2)O-Mg(NO3) 2 center dot 6H2O were predicted. Both mixtures present the same predicted melting temperature of 10.8 degrees C. Experimental verifications by T-history method showed satisfactory accordance of the predicted temperatures values with a difference of 0 degrees C and +2.3 degrees C for the mixtures, with sodium nitrate and magnesium nitrate, respectively. It is added that the thermal and physical properties such as density, the heat capacity for solid and liquid phases, as well as viscosity and volume change during the fusion of the new PCMs were evaluated. The results of the characterization, the energy storage density (about 300 MJ m(-3)) and material cost estimation show that both mixtures are promising candidates for use in low temperature energy storage systems.