Abbreviations
ASU	air separation unit
COP	coefficient of performance
NTU	number of thermal units
NEUD	number of exergy units destroyed
Latin Letters
A	heat transfer area, m2
C	purchase cost, Eur; heat capacity, kW/K
Cp	compressor
${\overline{c}}_p$	molar heat capacity, kJ/kmol/K
$\acute{E}x$	current of exergy, kW
$\overline{ex}$	molar exergy, kJ/kmol
F	exergetic fuel, kW
$\overline{h}$	molar enthalpy, kJ/kmol
$\dot{I}$	current of exergy destruction due to internal irreversibility, kW
$\overline{i}$	molar exergy destruction, kJ/kmol
L	exergetic loss, kW
p	pressure, Pa
$\overline{R}$	universal constant of gases, kJ/kmol/K
$\dot{S}$	current of entropy, kJ/kg/K/s
$\overline{s}$	molar entropy, kJ/kmol/K
t	temperature, °C
T	temperature, K
U	overall heat transfer coefficient, kW/m2/K
$\overline{w}$	molar mechanical work, kJ/kmol
$\dot{W}$	mechanical power, kW
Subscripts
0	environment, in equilibrium with the environment, difference between inlet temperatures in the heat exchanger
c	cold
cp	compressor
ex	exergetic
gen	generation
h	hot
i	inlet
L	loss
m	mean
max	maximum
min	minimum
o	outlet
Q	heat
Z	functional zone
Superscript
c	cold
cp	compressor
h	Hot
M	mechanical
T	thermal
Greek Symbol
ΔT	temperature difference
ε	thermal efficiency of the heat exchanger
${ɳ}_{s,cp}$	compression isentropic efficiency
π	compression ratio
ψ	share of an exergetic loss or destruction in the fuel consumption