A	heat transfer area (m2)
at	mole fraction
Cp	specific heat capacity (J/(kg·K))
Dh	hydraulic diameter (mm)
f	flow resistance coefficient
H	height (mm)
hm	mean heat transfer coefficient (W/(m2·K))
k	thermal conductivity (W/(m·K))
L	length (mm)
Nu	Nusselt number
PEC	performance evaluation criteria
Pr	Prandtl number
p	pressure (Pa)
Q	heat exchange capacity (W)
q	heat flux (W/m2)
Re	Reynold number
RH	hydraulic resistance (Pa·s/m3)
RThm	thermal resistance (K/W)
r	radius of inlet and outlet passages (mm)
T	Kelvin temperature (K)
tf	Fahrenheit temperature (°F)
u	velocity in x direction (m/s)
Vfr	volume flow rate (m3/s)
v	velocity in y direction (m/s)
W	width (mm)
w	velocity in z direction (m/s)
wt	weight fraction
x	Cartesian coordinate (m)
y	Cartesian coordinate (m)
z	Cartesian coordinate (m)
Greek symbols
ΔP	pressure drop (Pa)
η	dynamic viscosity (Pa·s)
λf	thermal conductivity (W/(m·K))
ρ	density (kg/m3)
Subscripts
b	heat sink bottom
c	microchannel
f	fluid
K	potassium
m	manifold
Na	sodium
w	wall