Effect of magnetic field on the forced convective heat transfer of water–ethylene glycol-based fe3 o4 and fe3 o4 –mwcnt nanofluids

Abstract

This paper discusses the forced convective heat transfer characteristics of water–ethylene glycol (EG)-based Fe3 O4 nanofluid and Fe3 O4 –MWCNT hybrid nanofluid under the effect of a magnetic field. The results indicated that the convective heat transfer coefficient of magnetic nanofluids increased with an increase in the strength of the magnetic field. When the magnetic field strength was varied from 0 to 750 G, the maximum convective heat transfer coefficients were observed for the 0.2 wt% Fe3 O4 and 0.1 wt% Fe3 O4 –MWNCT nanofluids, and the improvements were approximately 2.78% and 3.23%, respectively. The average pressure drops for 0.2 wt% Fe3 O4 and 0.2 wt% Fe3 O4 – MWNCT nanofluids increased by about 4.73% and 5.23%, respectively. Owing to the extensive aggregation of nanoparticles by the external magnetic field, the heat transfer coefficient of the 0.1 wt% Fe3 O4 –MWNCT hybrid nanofluid was 5% higher than that of the 0.2 wt% Fe3 O4 nanofluid. Therefore, the convective heat transfer can be enhanced by the dispersion stability of the nanoparticles and optimization of the magnetic field strength.