Rheological Behavior and Thermal Conductivity of Graphite–Ethylene Glycol Nanofluid

Abstract

The rheological behavior and thermal conductivity of graphite–ethylene glycol (EG) nanofluid is investigated in this research work. The nanofluid is prepared by two-step method using polyvinylpyrrolidone as surfactant. Volume concentration (vol. %) of 0.2, 0.8, and 2 % graphite-EG nanofluid are prepared by ultrasonicating for 5 h. Initially, the effect of temperature variation from 25°C to 60°C (with a difference of every 2.5°C) on the viscosity of prepared nanofluid for different volume concentrations is studied at a fixed shear rate of 25 s−1. The effect of shear rate from 0.1 to 100 s−1 on the viscosity of nanofluid is tested at a fixed temperature of 25°C. The nanoparticle size considered for analysis of viscosity is <50 nm. Viscoelastic behavior of the nanofluid with respect to change in amplitude and frequency is investigated for 0.2 vol. %. The viscosity analysis is carried out considering graphite nanoparticles of size <50 nm. Later, the thermal conductivity of prepared nanofluid is investigated at a constant temperature (25°C) for nanoparticle sizes of <50 and <100 nm. Finally, from this complete investigation it is concluded that the viscosity of nanofluid increased slightly from 17 to 19 cP with an increase in volume concentration but decreased by 58 % with an increase in temperature. The thermal conductivity for 2 vol. % nanofluid with nanoparticle size <50 nm is found to increase by 16.3 % compared with nanoparticle size <100 nm.

Improved Thermophysical Properties and Energy Efficiency of Aqueous Ionic Liquid/MXene Nanofluid in a Hybrid PV/T Solar System

“…Recently, carbon-based nanoparticles and two-dimensional nanostructures have captivated ample attention due to their comparatively higher thermal conductivity, greater specific surface area, better compatibility with base fluid, better lubricating property, and ample availability when compared with other nanoparticles [ 25 , 26 ]. A broad number of studies were performed with graphite [ 27 ], carbon nanotubes(CNTs) [ 28 , 29 ], graphene [ 30 ], graphene oxide (GO) [ 31 ], nano diamond [ 32 ], and graphite flake [ 33 ] nanoparticles so far. Yu et al [ 34 ] experimentally measured the thermal conductivity of EG based nanofluid with GO nanosheets where thermal conductivity was noticeably higher by 61% compared to pure EG, while the nanosheet concentration was 5 vol %.…”

Experimental investigation on thermal conductivity and stability of water-graphite nanofluid

“…This instrument works on the principle of the transient hot wire method (THWM). KD2 Pro is one of the simple and accurate method to measure thermal conductivity and has been used broadly by many researchers [39,[41][42][43][44]. This instrument consists of a battery, microcontroller and a sensor needle.…”

“…Nanoparticles of different sizes have been produced using several methods [37,38]. However, T -S method was widely adopted by the researchers in the preparation of many types of nanofluids [20,35,[39][40][41] due to ease in preparation of predetermined concentration. Graphite nanopowder (Sisco Research Lab (SRL), Maharashtra) with particle size <50 nm was procured to prepare Water -Graphite nanofluids.…”

Heat transfer characteristics and entropy generation analysis in a plate heat exchanger using ethylene glycol and water mixture‐based Al2O3 nanofluid

“…From the study, it was observed that 10.29% enhancement in viscosity was found for 2% of weight concentration at 20°C compared with base fluid. Brownian motion and van der Waals forces are the primary contributors 53,54 for the increase in viscosity of nanofluid. Accordingly, for 0.2, 0.5, 1, and 1.5 wt% concentration, the CHTC obtained was 6.43%, 14.25%, 23.61%, and 28.94% greater than that of base fluid respectively.…”

“…Nanofluids have distinct heat transfer characteristics compared with base fluids, such as improved thermal conductivity and greater heat transfer coefficients (HTC). [7][8][9][10][11][12] Researchers have reported significant improvement in heat transfer by using fluids dispersed with solid nanoparticles of different materials. [13][14][15][16][17] Studies have been reported using various techniques to investigate the synthesis, evaluation of properties and determination of heat transfer characteristics of nanofluids.…”