Skip to main content
. 2021 May 18;11(5):368. doi: 10.3390/membranes11050368
A Membrane area: m2 Sh Sherwood number, dimensionless
Ad Membrane area in cell, m2 Sc Schmidt number, dimensionless
Cb Bulk concentration, kgm−3 Pe Peclet number, dimensionless
CCL Boundary layer concentration, kgm−3 Wd Stability factor with respect to deposition (parameter in No. 4.4, Table 4)
Cg Gel concentration, kgm−3 s Sedimentation coefficient
Cgv Concentration gel layer in volume, m3 t Time, s
Cm Intrinsic concentration, kgm−3 tR Fouling phase time, s
Cp Permeated concentration, kgm−3 τ Tortuosity, dimensionless
C0v Feed concentration, kgm−3 T Temperature, °C
Dm Equivalent diffusion diameter of macromolecules (parameter in No. 1.11), m U Flow velocity, ms−1
D Diffusivity, m2s−1 U0 Initial flow velocity, ms−1
d Diameter of the module, m v(L) Average permeate velocity on the length of the filter channel, ms−1
dh Hydraulic diameter, m vf Local filtrate velocity (parameter No. 1.8), ms−1
dp Pore diameter, m X(t) Position change of the equilibrium zone (parameter in No. 4.5)
F Intermolecular interactions b Radius of the stirred cell (parameter of No. 1.8)
fc Marchetti correction factor V Permeate volume (parameter in No. 3.10), L
fcp Capilar effect Vc Permeate volume at the reference time point (parameter in No. 3.10), L
b Inverse of the solute density (parameter of No. 1.9) V Permeate volume, m3
H Height of liquid over membrane (parameter of No. 1.9), m V0 Initial permeate volume, m3
η Non-dimensional distance (parameter of No. 1.9) = x/H v Specific partial volume, kgm3
ϕ Non-dimensional concentration (parameter of No. 1.9) = c/co v0 Specific partial initial volume, kgm3
fd Dipole effect VRF Volume reduction factor, dimensionless
fe Steric effect v Kinematic viscosity, m2s−1
H Thickness of the gel layer, m xi Proportional parameter of permeability in No. 1.3
J Permeate flux, ms−1 ∆x Membrane thickness, m
Jf Final permeate flux, ms−1 X12 Flory-Huggins parameter
Jlim Limit permeate flux, ms−1 z* Axial position for osmotic pressure, m
J Saturation (equilibrium) volumetric permeate flux, m3m−2s−1
Jss Steady-state permeate flux, ms−1 Greek symbols
JW Flux of pure water permeate, ms−1 δ Thickness of the boundary layer, m
J* Hydraulic lifting speed, ms−1 ∆π Osmotic pressure, Pa
Jo Balance between solute input and output, γ Shear rate, ms−1
k Mass transfer coefficient, ms−1 γm Shear rate at the wall (parameter in No. 1.11), s−1
ko Ideal mass transfer coefficient, ms−1 Ɛ Porosity of the membrane, dimensionless
K Boltzmann constant (parameter in No. 1.11), Jmol−1K−1 α Specific resistance of the deposit on membrane, kgm2
L Length of the module, m ϵ Specific gel resistance, m−2
Lp Membrane permeability, mPa−1s−1 ƐCL Boundary layer porosity, dimensionless
Lph Effective permeability reverse flow, β Parameter of No. 1.5
mp Deposited cake weight, kg σ Reflection coefficient
MW Membrane cut-off limit, gmol−1 Ɛg Solidity of the gel layer, %
∆P Transmembrane pressure, Pa εst Steady-state value of the average solidity, %
Q Flow rate, m3s−1 μ0 Initial viscosity, Pa s
Rm Membrane resistance, m−1 μb Viscosity in the bulk, Pa s
RM Fouled membrane resistance, m−1 μ Viscosity, Pa s
Rad,ss Adsorption resistance, m−1 ρ Feed density, kgm−3
Rcp Concentration polarization resistance, m−1 ρpol Membrane polymer density, kgm−3
Rcp,ss Steady-state concentration polarization resistance, m−1 γa Axial speed, ms−1
Re Reynolds number, dimensionless υpo Osmotic pressure limiting flux (m3 m−2 s−1)
Rf Irreversible resistance, m−1 X12 Flory–Huggins interaction parameter
Rg Gel resistance, m−1 ϕ Volume fraction of particles at the distance x from the membrane surface
Rm Hydraulic resistance, m−1 ϕ 1/Jlim (parameter of No. 3.11), m2sm−3
Rm* Experimental resistance (constant ΔP), m−1
Rm i−1 Accumulated resistance at ti−1,
Rps* Concentration polarization differential resistance, dimensionless
Rt Total resistance, m−1
rCL Specific resistance of the boundary layer, m−1
ri Cell radius, m
ro Initial cell radius, m
rp Particle radius, m
rpp Membrane pore radius, m