Rheological Behavior and Effective Thermal Conductivity of Non-Newtonian Nanofluids

Abstract

Abstract The rheological behavior and effective thermal conductivity of CMC-based non-Newtonian nanofluids were investigated. Non-Newtonian nanofluids of different concentrations were prepared by dispersing Fe2O3, γ-Al2O3 and CuOnanoparticles in three different concentrations of (0.5, 0.75, and 1.0 wt. %) aqueous carboxymethyl cellulose (CMC) solution (base fluid). Experiments were carried out to examine the effect of concentration of nanofluid and temperature on rheological behavior and effective thermal conductivity of non-Newtonian nanofluid. Viscosity and thermal conductivity were measured by rheometer and transient hot wire technique, respectively. The rheological characterization and thermal conductivity measurements were done in the range 30°C–50°C. Flow behavior index and consistency index were determined. As the concentration of nanofluid and temperature were increased, the thermal conductivity of nanofluid was found to increase. A correlation for predicting the thermal conductivity of non-Newtonian nanofluid was developed. The correlation predicted the thermal conductivity of non-Newtonian nanofluids reported by other researchers very well. The results obtained were compared with the model predictions from literature.