Symbols
A	Cross sectional membrane area, m2
dpore	Pore diameter, m
Eact	Activation energy of permeability, J/mol
f	Fugacity, Pa
L	Permeance, mol∙m/(m2∙s∙Pa)
m 0	Swelling factor at zero temperature, Pa−1
mT	Factor of temperature dependency of the swelling, K−1
M	Molecular weight, kg/mol
$\stackrel{·}{n}$	Flow rate, mol/s
${\stackrel{·}{n}}^{”}$	Molar flux through the membrane divided by area, mol/(m2∙s)
p	Pressure, Pa
P	Permeability coefficient, mol∙m/(m2∙s∙Pa)
R	Gas constant, 8.314 Pa∙m3/(mol∙K)
t	Time, s
T	Temperature, K
V	Volume, m3
$\stackrel{·}{V}$	Volumetric flow rate, m3/s
Greek symbols
∆α	Thermal expansion coefficient, K−1
$\delta$	Thickness of layer j, m
ε	Fractional void volume of porous medium
η	Dynamic viscosity of the gas, Pa∙s
τ	Tortuosity factor
Subscripts
a	Average
act	Activation
F	Feed
G	Gutter layer
i	Component i
j	Layer j
P	Permeate
pore	Pore
PS	Porous support
S	Selective layer
t	Total
T	Temperature
W	Pore wall
∞	Temperature → ∞
Superscripts
∙	Time derivative
´´	Area derivative
0	Pressure → 0