Radiative transport of hybrid nanofluid

Hybrid nanofluids are a new class of nanofluids that have been reported to show better thermophysical and optical properties. Hybrid nanofluids are prepared by the dispersion of two or more nanoparticles in a conventional heat transfer fluid. These hybrid nanofluids can be used in direct absorption solar thermal systems as a working fluid. Therefore, it becomes essential to study the optical properties of hybrid nanofluids. Different nanoparticles have different properties; for example, Al₂O₃ nanoparticles have higher heat capacity but a low absorption spectrum compared with CuO nanoparticles. For direct solar absorption applications, it is essential to estimate the optical properties of hybrid nanofluids. Different theories predict the extinction coefficient; among them, the Mie scattering theory is the most suitable. Different theories have been discussed in the present study to calculate the extinction coefficient theoretically, and these theoretical values of the extinction coefficient are compared with experimentally obtained values.