A	Area of heat exchanger	m 2
corr	Slip coefficient	-
c p	Specific heat capacity	kJ·kg -1·K -1
Ċ	Heat capacity	kW·K -1
COP	Coefficient of performance	-
d	Diameter	m
h	Enthalpy	kJ·kg -1
K	Friction factor	1/m 4
L	Characteristic length	m
M	Mach number	-
ṁ	Mass flow rate	kg·s -1
N	Compressor speed	s -1
n	Efficiency	-
Nu	Nusselt number	-
P	Pressure	kPa
Pr	Prandtl number	-
$\dot{Q}$	Thermal capacity	kW
Re	Reynolds number	-
r v	Build-in volume ratio	-
s	Specific entropy	kJ·kg -1·K -1
T	Temperature	°C
U	Overall heat transfer coefficient	kW·m -2·K -1
u	Velocity	m·s -1
v	Specific volume	m 3·kg -1
${\dot{V}}_s$	Volumetric flow rate	m 3·s -1
V	Volume	m 3
w	Specific work	kJ·kg -1
Ẇ	Compressor electrical power	kW
Z	Number of data sets	-