Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3.

Solomon O Giwa,Mohsen Sharifpur,S M Sohel Murshed,Mohammad H Ahmadi,Josua P Meyer

doi:10.3390/nano11010136

Abstract

The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

Highlights

Outside the viscosity and thermal conductivity, the electrical conductivity (EC), specific heat capacity, dielectric, and density of various nanofluids prepared from different nanoparticles (Cu, MgO, CuO, carbon nanotubes (CNTs), SiO2, ZnO, TiO2, Al2 O3, Fe2 O3, Fe3 O4, spinels etc.) and dispersed in several base fluids have been subsequently examined at various mass/volume concentrations or fractions for different temperature ranges [14,15,16,17,18,19,20]
The results showed that the hybrid nanofluid with a mixture ratio of 60:30:10 (CuO-MgO-TiO2 ) was the best as it had the lowest viscosity (36.4% for 0.5 vol% at 60 ◦ C), highest thermal conductivity
The electrical conductivity has been reported as a viable property that can be employed to achieve the critical micelle concentration (CMC) of the surfactant utilized for nanofluid preparation [41,42]

Summary

Introduction

The exceptional thermal and flow properties exhibited by nanofluid compared with those of conventional thermal transporting media have projected this special fluid as a subject of intense global research Studies in this context have measured the viscosity and thermal conductivity of nanofluids with diverse base fluids (ethylene glycol (EG), water, propylene glycol, glycerol, etc.) and found that these properties of the nanofluids were enhanced in relation to the base fluids [1,2,3,4,5,6,7,8,9,10]. Hybridization of different types of nanoparticles to prepare hybrid nanofluids was first investigated by Jana and co-workers [21] The idea behind this was to augment the thermal conductivity of nanofluid over that of conventional fluids.

Methods

Results

Conclusion