Improving thermal energy storage and transfer performance in solar energy storage: Nanocomposite synthesized by dispersing nano boron nitride in solar salt

Abstract

Solar salt (SS) is an energy storage material widely used in concentrating solar power (CSP) stations at industrial thermal energy storage (TES) systems in the current. Hence, a conventional high-temperature static melting method was used to prepare nano hexagonal boron nitride-SS (h-BN-SS, BS system) composite materials with different content of nano BN to improve the heat storage and transfer performance of SS. The specific heat (cp) of 1.81 J·g−1·K−1 was obtained at nano BN content of 0.8 wt% (sample BS6), which had increase of 16.03% compared with pure SS (sample BS0). The crystal planes (104) and (221) of nitrate appeared on the surface of nano BN (100), promoted the enhancement of surface energy of whole system. The using temperature zone was widened and thermal conductivity (λ) had been increased by 18.52%. The existence forms of nano BN hadn't changed at high temperature, and the cation environment around NO3− of BS0 and BS6 were changed after adding nano BN demonstrated by high temperature Raman spectroscopy. Moreover, BS6 had excellent thermal stability at long-term thermal stability measurement within 7200 min. The observations suggested that nano BN may serve as promising additive for solar energy storage material toward TES system applications.