Zirconium diboride-based nanofluids for solar energy applications

Abstract Direct absorption solar collector (DASC) are being considered of great interest in combination with colloidal systems consisting of nanoparticles dispersed in suitable liquids, also called nanofluids. Nanofluids are able to carry out, at the same time, the double function of volumetric solar absorbers and heat transfer media. In this work, novel ceramic nanoparticles of zirconium diboride (ZrB2) have been synthesized, dispersed in ethanol and characterized from points of view of microstructure, stability and optical properties. ZrB2 is representative of the family of Ultra-High Temperature Ceramics (UHTCs). Some of their peculiar characteristics, in particular ultra-refractoriness, high-temperature stability and promising bulk optical properties favourably compared bulk UHTCs to conventional solid solar absorbers used in Concentrated Solar Power to date. The present work, for the first time, shows the optical spectra of ZrB2 nanoparticles. We prove the appealing optical properties of ZrB2 nanofluids for direct-absorption solar thermal collectors. This opens a new application field for UHTCs.