Broadband absorbing mono, blended and hybrid nanofluids for direct absorption solar collector: A comprehensive review

The evolution of nanofluids over the years have opened new research opportunities in the field of renewable energy. Research on the optical properties of nanofluids for application in direct absorption solar collectors (DASCs) is progressing at a burgeoning speed. In a direct absorption solar collector system, nanofluid with high optical absorptivity will convert the incident solar energy to the thermal energy of the fluid. The dispersed nanoparticles in the fluid acts in the process by the phenomenon of absorption and scattering. Studies conducted on the optical property characterization of monocomponent nanofluids have become saturated. Moreover, the photothermal efficiency of the nanofluid could be enhanced by using multicomponent nanofluids. Nanofluid prepared by varying materials, shapes, and size of nanoparticles could tune the absorption spectra of the bulk fluid to improve the photothermal efficiency. A hybrid nanocomposite can similarly enhance the absorptivity due to the synergy of materials present in the nanocomposite particle. In this review, a comprehensive survey on the synthesis and optical characterization of different blended and hybrid nanocomposite nanofluids have been performed. Besides, works on different mono nanofluids that have been studied over the years have been reviewed.