Natural convection of hybrid nanofluids inside a partitioned porous cavity for application in solar power plants

Abstract

The present article deals with the CFD simulation of natural convection heat transfer of a hybrid nanofluid in an inverted T-shaped cavity partitioned and saturated by two different types of porous media. Suspensions of organic and inorganic nanoparticles, i.e., MWCNTs and Fe3O4, in water were selected as the working fluid. The macroscopic conservation equations for the flow field and heat transfer were modeled via volume averaging the microscopic equations inside porous media over a representative elementary volume. The effects of many parameters were investigated. The parameters included the Rayleigh number (Ra\u2009=\u2009103–106), porosity coefficient ratio of two porous media (εr\u2009=\u20090.5–1.8), volume fraction of the dispersed nanoparticles ($$\\varphi$$φ\u2009=\u20090–0.003), Richardson number (Ri\u2009=\u20090.1–20), Darcy number ratio of two porous media (Dar\u2009=\u20090.01, 1, 100) and thermal conductivity ratio of two porous media (kr\u2009=\u20090.2, 0.4, 1, 5). The results showed that, with an increase in the Rayleigh number, porosity ratio and Darcy number ratio and decrease in the thermal conductivity ratio, the averaged Nusselt number increased.Graphical abstract