Figure 13 Comparison of
experimental values of viscosity for SiO2/60EGW
nanofluids with theoretical correlations (6) and (12)
Similarly, the experimental viscosity values of
SiO2/40EGW nanofluids are compared with base fluid
correlation (10) and nanofluid correlation (14) and are plotted inFigure 14 . The viscosity measurements were taken in the same
operating conditions of SiO2/60EGW nanofluids as
mentioned. A deviation less than 18% was observed with correlation
(18). Additionally, the study established that given different
concentrations, an increase in temperature causes a significant decrease
in the nanofluids’ viscosity. As such, SiO2 nano
particle loading was observed to cause an increase in flowing resistance
and friction of the fluids, translating into increased viscosity.
The viscosity enhancement was plotted against temperature for the two
given nanofluids in Figure 15 . It is quite clear that
SiO2/40EGW shows a good enhancement in viscosity with a
maximum enhancement of 102% than the base fluid at 1.5% volume
concentration and 25oC temperature. Based on the
observations 40EGW based nanofluids shows a higher enhancement in
viscosity. This study indicates that, with the increase in percentage of
ethylene glycol, the viscosity of SiO2 nanofluids also
increases. The measurements have similar finding as Lotfizadeh Dehkordi
et al. [61] who have used Al2O3dispersed in 60EGW and 40EGW base fluids by mass % and also Syam
[62] has observed enhancement of 300% and they attributed it to the
shear resistance offered by the particles onto the fluid layer. With
larger the particle concentration in the base fluid, larger the quantity
is of particles are required.