Review on thermal efficiency augment of flat plate collector equipped with mono and hybrid nanofluids and with inserts

Abstract

Enhanced utilization of renewable energy resources is essential to meet the growing global energy demand and address the depletion of conventional energy sources. Solar energy, as a renewable and eco-friendly resource, plays a pivotal role in this transition. Solar collectors, including flat plate collectors (FPCs), parabolic collectors, and others, are devices designed to convert solar energy into useful thermal energy. This article investigates the influence of nanofluids on the thermal performance of FPCs, with a specific focus on thermal efficiency. Water-based mono nanofluids containing Al₂O₃, CuO, MWCNTs, TiO₂, SiO₂, and ZnO, along with hybrid nanofluids such as SiC-MWCNT/ethylene glycol, MgO-MWCNT/water, CuO-MWCNT/water, and Al₂O₃-TiO₂/water, were analyzed for their ability to enhance the thermal efficiency. The study comprehensively examines the Nusselt number, friction factor, and thermal efficiency of FPCs operating with these nanofluids, both with and without inserts in the absorber tubes. The study also explores the performance under the natural and forced circulation. Additionally, existing correlations for Nusselt number and friction factor for nanofluids with and without inserts in the absorber tube have been reviewed.