A	cross-sectional area	m
c	speed of light in vacuum	m·s−1
d	thickness	m
E	electric field vector	V·m−1
G	dyadic Green function	m−1
H	magnetic field vector	A·m−1
ħ	Planck constant divided by 2π	J·s
J	energy flux density	W·m−2
k	material extinction coefficient	-
k B	Boltzmann constant	J·K−1
m	numbers of small air square	-
n	refractive index	-
n	normal vector	-
N	particle numbers unit numbers of small solid square	-
P	scattering phase function	-
r	radius of polymer particles/Fresnel reflection coefficient	m/-
S	specific surface area	m2·kg−1
T	temperature	K
t	Fresnel transmission coefficient	-
q″	heat flux	W·m−2
x,y,z	coordinate direction	-
Θ	mean energy of the Planck oscillator	J
κ	thermal conductivity	W·m−1·K−1
ρ	density	kg·m−3
ε	relative permittivity	F·m−1
α	material absorption coefficient	-
β	energy interaction between gaseous molecules and the solid surface	-
σ	the coefficient	-
σ SB	Steven-Boltzmann constant.	-
λ	wavelength	m
φ	porosity	-
μ	the permeability	H·m−1
ω	angular frequency	rad·s−1
Λ	phonon mean free path	m
Subscript
a	absorption
bulk	dielectric skeleton
cond	thermal conduction
e	extinction
evan	evanescent wave
g	gas
H	cell size
mp	maximum emissive power peak
p	equivalent pore size
prop	propagating wave
rad	thermal radiation
s	solid/scattering
total	total heat transfer
w	equivalent wall size
z	z direction
Superscript
s	s polarization
p	p polarization