Experimental study of nanofluids flow and heat transfer over a backward-facing step channel

Abstract

The forced convective heat transfer and friction factor of nanofluidsflow over a backward-facing step (BFS) in achannel with the base wall dissipating a uniform heatflux are experimentally investigated in this paper. Nano-particles such as CuO and MgO dispersed in pure ethylene glycol (EG) with average diameters of 40 nm, and vol-ume concentrations of 0, 1, 3, and 5% are considered as the working nanofluids. The results indicate that the heattransfer rate increases as the volume concentration of nanoparticles increased. The Nusselt number is enhancedup to 11% at 0.05 volume concentration compared to pure EG. The friction factor increases up to approximately 15% at Reynolds number (Re) of 5000 and volume concentrations of 0.01 and 0.03. The maximum value ofthe PEC in a BFS channel is 1.5 for the CuO-EG and 1.2 for the MgO-EG at a volume concentrations of 0.03 and Re=20,000.