Effects of temperature and nanoparticles concentration on rheological behavior of Fe3O4–Ag/EG hybrid nanofluid: An experimental study

• Published in: Experimental thermal and fluid science Vol. 77; pp. 38 - 44
• Main Authors: Afrand, Masoud, Toghraie, Davood, Ruhani, Behrooz
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2016
• Subjects: Ag nanoparticles; Ethylene glycol; Experimental study; Fe3O4 nanoparticles; Non-Newtonian hybrid nanofluid; Ethylene glycol; Ag nanoparticles; Non-Newtonian hybrid nanofluid; Experimental study; Fe3O4 nanoparticles
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2016.04.007

•Preparing stable and homogenous Fe3O4–Ag/EG hybrid nanofluid using two-step method.•Examination of effects of temperature and concentration on viscosity of nanofluid.•Low-concentration samples (φ<0.3%) had Newtonian behavior.•High-concentration samples (φ>0.3%) followed power-law non-Newtonian model.•Finding consistency index and power law index by curve-fitting. In this paper, the effects of temperature and nanoparticles concentration on the rheological behavior of Fe3O4–Ag/EG hybrid nanofluid have been experimentally investigated. Stable and homogeneous suspensions were prepared in solid volume fractions of 0.0375%, 0.075%, 0.15%, 0.3%, 0.6% and 1.2%. Viscosity measurements were performed at different shear rates (12.23–122.3s−1) under temperatures ranging from 25°C to 50°C. Results revealed that the nanofluid samples with solid volume fractions of less than 0.3% had Newtonian behavior, while those with higher solid volume fractions (0.6% and 1.2%) had non-Newtonian behavior, and followed the power-law model. Finally, the consistency index and power-law index were obtained from curve-fitting on shear stress–shear rate dependency. Curve-fitting results showed that all power-law indices were in the range of 0.5339–0.6706, indicating that the nanofluid samples possessed shear-thinning behavior at all temperatures considered.