Ankit Kotia and Subrata Kumar Ghosh
The present work aims to numerically investigate the natural convective heat transfer performance of aluminium oxide (Al2O3)-gear oil nanolubricant used in heavy earth moving…
Abstract
Purpose
The present work aims to numerically investigate the natural convective heat transfer performance of aluminium oxide (Al2O3)-gear oil nanolubricant used in heavy earth moving machinery (HEMM).
Design/methodology/approach
Viscosity, density and thermal conductivity of nanolubricants have been experimentally determined. The numerical simulation has been performed by using computational fluid dynamics (CFD) for a cylinder cavity which resembles shape of automatic transmission system of HEMM. The left wall temperature has been maintained at 293 to 313 K, and right wall is at a constant temperature of 283 K. Due to absence of any experimental study on natural convective heat transfer performance of Al2O3-gear oil nanolubricant, initially CFD model has been tested for accuracy by comparing experimental, and CFD results for Al2O3-water nanofluid has been available in open literature.
Findings
It has been observed that Nusselt number increases with increase in Rayleigh number, but it decreases with increasing particle volume fraction. The gear oil-based nanolubricant is expected to have the better thermal performance in HEMM at higher temperature.
Practical implications
The numerical analysis will help to predict the thermal performance of nanolubricant. The outcome may help the designers, researchers and manufacturers of HEMM.
Originality/value
Most of the previous studies have been limited with base fluid as water, ethylene glycol, etc. in the field of nanofluid. CFD study for thermal performance of Al2O3-gear oil nanolubricant is essential before the experimental work. This work is the preliminary stage of application of, nanolubricant for heat transfer.
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Ankit Kotia and Subrata Kumar Ghosh
The purpose of this paper is to experimentally investigate the effect of aluminium oxide (Al2O3) nanoparticles on gear oil (SAE EP 90) as a lubricant in heavy earth moving…
Abstract
Purpose
The purpose of this paper is to experimentally investigate the effect of aluminium oxide (Al2O3) nanoparticles on gear oil (SAE EP 90) as a lubricant in heavy earth moving machinery (HEMM).
Design/methodology/approach
Particle size distribution, viscosity, density, stability and other rheological properties have been measured. The variations in rheological properties with varying nanoparticle volume fraction and temperature have been investigated at atmospheric pressure over a temperature range of 15-40°C. Classical as well as modified Krieger – Dougherty models have been used for finding out viscosity variation and a new empirical model has been presented.
Findings
Dynamic light scattering data confirm the presence of large agglomeration of about 5.5 times of primary nanoparticles in nanofluid. Nanofluid starts behaving as a non-Newtonian fluid with increasing nanoparticle volume fraction. Viscosity of nanofluid is enhanced by 1.7 times of base fluid with 2 per cent volume fraction of Al2O3 nanoparticles, while it significantly decreases with increase in temperature. The stability of nanofluid decreases with increase in nanoparticle volume fraction due to settling down of nanoparticles. It has also been observed that shear thinning increases with increasing nanoparticle volume fraction.
Practical implications
It is expected that these findings will contribute towards the improvement in rheological and thermal properties of the conventional lubricants used in HEMM. The outcome may help the designers, researchers and manufacturers of the HEMM.
Originality/value
Most of the previous research in this field is confined with base fluid as water, ethylene glycol, transformer oil, etc. Gear oil in HEMM performs under high mechanical and thermal load. The Al2O3/gear oil nanofluid is expected to have better cooling and lubrication properties.