Advances of nanofluids in solar collectors - a review of numerical studies

Abstract

This paper presents a detailed review of the numerical studies carried out by various researchers in order to obtain enhanced heat transfer in free, forced, and mixed convection, under laminar, transition, and turbulent flow regimes, by using nanofluids in different solar collector geometries. Recently, nanofluids have been increasingly used in various solar collector configurations. Nano-sized metallic or non-metallic particles such as Cu, Au, Al2O3, SiO2, TiO2, CuO, etc, were used in the heat transfer fluid for various solid volume fractions. The average size of the particles was less than 100 nm. The higher conductivity of nanoparticles even at low particle concentration results in higher thermal conductivity of the base fluid and improves the thermal characteristics of the system. Nanoparticle size, type and shape are important factors for the thermal conductivity enhancement of the nanofluid with nanoparticles.