A	cross-sectional area, m2
BCs	boundary conditions
CFD	computational fluid dynamics
CHP	combined heat and power
CHT	conjugate heat transfer
${\mathrm{Cp}}_{\mathrm{c}/\mathrm{h}}$	heat capacity at constant pressure for cold/hot inlet microchannels, J/(K.kg)
${\mathrm{C}}_{\mathrm{c}}$	cold fluid capacity rate, W/(K)
${\mathrm{C}}_{\mathrm{h}}$	hot fluid capacity rate, W/(K)
${\mathrm{D}}_{\mathrm{h}}$	hydraulic diameter, mm
L	microchannel length, mm
${\mathrm{m}}_{\mathsf{\mu }},{\mathrm{m}}_{\mathsf{\mu }\mathrm{c}},{\mathrm{m}}_{\mathsf{\mu }\mathrm{h}}$	microchannel mass flow rate for cold/hot inlet channels, $\frac{\mathrm{kg}}{\mathrm{s}}$
${\mathrm{m}}_{\mathrm{co}}$	collector inlet mass flow rate for cold/hot inlet side, $\frac{\mathrm{kg}}{\mathrm{s}}$
${\mathrm{m}}_{\mathsf{\mu }\mathrm{CHT}}$	microchannel mass flow rate calculated from CHT model inlet, $\frac{\mathrm{kg}}{\mathrm{s}}$
w	width of the microchannel, mm
h	height of the microchannel, mm
${\mathrm{n}}_{\mathrm{pl}}$	number of plates
PM	porous medium
$\mathrm{P},{\mathrm{P}}_{\mathrm{in}},{\mathrm{P}}_{\mathrm{out}},{\mathrm{P}}_{\mathrm{ab}}$	inlet/outlet total pressure and absolute pressure, Pa
ROM	reduced order model
R	universal gas constant, $\frac{\mathrm{J}}{\mathrm{mol}\mathrm{k}}$
Re	Reynolds number
S1	Sutherland constant
T	temperature, K
${\mathrm{T}}_{\mathrm{in},\mathrm{out}}^{\mathrm{h},\mathrm{c}}$	inlet and outlet total temperatures for hot \- cold microchannel inlets and outlets, K
Tav	is the average temperature of the gas between the inlet and outlet, K
$\mathsf{\Delta }\mathrm{T}$	temperature drop across the microchannel length, K
$\mathsf{\Delta }\mathrm{P}$	pressure losses across the length, Pa
Q	thermal source term, $\frac{\mathrm{W}}{{\mathrm{m}}^3}$
$\mathrm{U},{\mathrm{U}}_{\mathrm{in}}$	stream wise mean velocity, inlet velocity, $\frac{\mathrm{m}}{\mathrm{s}}$
$1/\mathsf{\alpha }$	viscous coefficient, ${\mathrm{m}}^{-2}$
β	inertial coefficients, ${\mathrm{m}}^{-1}$
$\mathsf{\beta }1$	ratio of the depth over the width of the microchannel
Υ	microchannel size reduction coefficient
ρ	density, kg/m3
$\mathsf{\mu }$	dynamic viscosity of the Nitrogen gas, kg/(m·s)
ε	thermal efficiency, %
Єm	turbulent viscosity, m2·s−1