Magnesium oxide nanoparticles dispersed solar salt with improved solid phase thermal conductivity and specific heat for latent heat thermal energy storage

• Published in: Renewable energy 2019-10, Vol.141, p.451-459
• Main Authors: Saranprabhu, M.K., Rajan, K.S.
• Format: Article
• Language: English
• Subjects: Latent heat thermal energy storage system; MgO nanoparticles; Solar salt; Solidification time; Specific heat; The rate of discharge
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2019.04.027

Composites comprising MgO nanoparticles as the dispersed phase and solid phase solar salt as the matrix have been prepared through solid-state mixing. The inclusion of MgO nanoparticles had very little influence on the solid-liquid phase change temperature and the latent heat of solar salt. However, the solid phase thermal conductivity of MgO-solar salt was elevated by 17.5% with the dispersion of 0.25 wt% MgO nanoparticles. The clustered nature of MgO nanoparticles and their presence at the interface between solar salt particles with reduced resistance might have contributed to the solid phase thermal conductivity enhancement for this composition of the composite. The maximum enhancement in specific heat of MgO-solar salt composite (14%) was observed at another composition (1 wt%), revealing the requirement of different composition for optimum thermal conductivity and optimum specific heat. The solidification time for 0.25 wt% composite was 30% lower than that of the solar salt. Also, the rate of discharge from 0.25 wt% composite was 42.4% higher than that of solar salt. The corresponding data for the composite containing 2 wt% MgO are 13.8% and 33.8% respectively. These composites can be used in latent heat thermal energy storage systems. •MgO-solar salt composite phase change material prepared and characterized.•0.25 wt% composite showed needle-like structures at the MgO-solar salt interface.•Different optimum MgO concentrations for maximum ‘k’ and ‘cp’ enhancement.•Maximum thermal conductivity enhancement of 17.5% for composite with 0.25 wt% MgO.•30% reduction in solidification time for 0.25 wt% MgO-solar salt composite.