γ	Alpha phase
ANL	Argonne National Laboratory
CNTs	Carbon nanotubes
$C_p$	Specific heat capacity (kJ/kg·K)
DIW	Deionized water
DW	Double-walled
EG	Ethylene glycol
$\eta$	thermal-hydraulic performance
f	Friction factor
${\mathrm{f}}_{\mathrm{V}}$	Volumetric concentration
h	Convective heat transfer coefficient (W/m2·K)
HE	Heat exchanger
hnf/hw	Relative convective heat transfer coefficient
ṁ	Volume flow rate (lpm)
MW	Multi-walled
Nu	Nusselt number
P	Pressure (Pa)
Pe	Peclet number
PFHEs	Plate-fin heat exchangers
PHEs	Plate heat exchangers
Re	Reynolds number
SANSS	Submerged arc nanoparticles synthesis system
SEM	Scanning electron microscope
SW	Single-walled
T	Temperature
TC	Thermal conductivity (W/m·K)
TEM	Transmission electron microscope
u	Flow velocity
$\mathrm{V}$	Volume (m3)
VEROS	Vacuum evaporation onto a running oil substrate
vol. %	Volume percentage
wt. %	Wight percentage
X	spacing distance (mm)
Greek letters
$\mathsf{\rho }$	Density (kg/m3)
Δ	Difference
Subscripts
bf	Basefluid
h	Hot
i	Used nanofluid
nf	Nanofluid
np	Nanoparticles
ref	Reference liquid
w	Water