Subsequently, engines are designed
to operate at low viscosity
engine oils. Low viscosity oils take less power from engines, bring
down the internal drag, cut the fuel consumption, and ultimately improve
the engine’s efficiency. Considering this focus, an approach
has been made to formulate a multiwalled carbon nanotube based green
tea and polyaniline nanocomposite, that is, GT/MWCNT/PANI, and incorporate
it in engine oil (base fluid). The objective was to reduce the viscosity
of engine oil by examining the effects of the constant shear rate
and varying shear rates on the viscosity of Castrol class 15W-40 engine
oil. The investigation was performed at a constant temperature of
25 °C for a fixed volume fraction of 0.1% GT/MWCNT/PANI in engine
oil on the experimental setup rheometer from Anton Paar Series. Primordial
findings revealed that, at a constant shear rate of 100 s–1, engine oil viscosity was lowered from 0.221000 to 0.001402 Pa·s,
that is, 99% reduction in viscosity of the engine oil, after incorporating
the GT/MWCNT/PANI nanocomposite. Furthermore, a new correlation has
been proposed considering the experimental and theoretical models
with an average percentage error of 0.040%. Also, at varying shear
rates, up to 90 s–1, the shear viscosity of nanofluid
decreases significantly, leading to shear-thinning behavior of the
nanofluid, while at a shear rate of >90 s–1,
it
shows Newtonian behavior. Besides, the ternary nanocomposite with
0.2 wt % GT/MWCNT/PANI also showed significant bactericidal effects
with the zones of inhibition of 19, 18, and 15 mm against Gram-negative
(Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, respectively, as
measured using the well diffusion method.