Symbols
J	Permeation flux (kg·m−2·s−1)
K	Membrane distillation coefficient (kg·m−2·s−1·pa−1)
p	Pressure (Pa)
X NaCl	Molar fraction of solute
T	Temperature (K)
γ	Activity coefficient
W	Mass fraction
M	Molar mass (kg·mol−1)
K n	Knudsen number
λ	Average free path of water vapor (μm)
d	Diameter of membrane pore (μm)
K B	Boltzmann constant (J·mol−1·K−1)
β	Collision diameters(μm)
D Wa	Diffusion coefficient of water vapor (m2·s−1)
p t	Gas pressure in the pore of the membrane
ε h	Surface porosity
τ	Membrane tortuosity factor
δ	Membrane thickness (mm)
R	Gas constant (J·mol−1·k−1)
r	Membrane pore radius (μm)
μ	Viscosity (pa·s)
q	Heat flux (w·m−2)
ΔH V	Enthalpy of evaporation (kJ·kg−1)
κ	Thermal conductivity (J·m−1·k−1)
ρ	Density (kg·m−3)
S	Source term
b	Thickness of the first grid layer (mm)
$\stackrel{=}{\tau }$	Stress tensor (kg·m−1·s−1)
$\rho \overrightarrow{g}$	Gravitational body force
$\overrightarrow{F}$	External body force
k	Turbulent kinetic energy
σ	Turbulent Prandtl number
Gb	Turbulence kinetic energy (buoyancy)
Gk	Turbulence kinetic energy (the mean velocity gradients)
Y M	Contribution of the fluctuating dilatation
C 1	constant
C 2	constant
C 1e	constant
C 3e	constant
Superscript
S	Saturation properties
Subscripts
m	Membrane
f	Feed side
p	Permeate side
W	Flow channel
v	Vapor
w	Water
MD	Molecular diffusion
K	Knudsen diffusion
K-MD	Knudsen-molecular diffusion
PO	Poiseuille flow
g	Gas
D	DCMD
H	Latent heat
C	Heat conduction
a	Air
s	Solid
eff	Effective
j	Component