Page 22 - Separation process principles 2

xxvi Nomenclature

x mole fraction in liquid phase; mole fraction in y vector of mole fractions in vapor phase
any phase; distance; mass fraction in raffinate; Z compressibility factor = PuIRT; total mass;
mass fraction in underflow; mass fraction of height
particles
Zf froth height on a tray
x normalized mole fraction = I ZL length of liquid flow path across a tray
lattice coordination number in UNIQUAC and
x vector of mole fractions in liquid phase
UNIFAC equations
x, fraction of crystals of size smaller than L
z mole fraction in any phase; overall mole frac-
Y mole or mass ratio; mass ratio of soluble mate- tion in combinedphases; distance; overall mole
rial to solvent in overflow; pressure-drop fraction in feed; dimensionless crystal size;
factor for packed columns defined by (6-102); length of liquid flow path across tray
concentration of solute in solvent; parameter
z vector of mole fractions in overall mixture
in (9-34)
mole fraction in vapor phase; distance; mass Greek Letters
y
fraction in extract; mass fraction in overflow

thermal diffusivity, ; relative volatility; surface area per adsorbed molecule

ideal separation factor for a membrane rnVIL; radiation wavelength
relative volatility of component i with respect limiting ionic conductances of cation and anion, re-
to component j for vapor-liquid equilibria; spectively
parameter in NRTL equation
energy of interaction in Wilson equation
energy-balance parameters defined by (10-23) to
chemical potential or partial molar Gibbs free
(10-26)
energy; viscosity
relative selectivity of component i with respect
momentum diffusivity (kinematic viscosity), ;
to component j for liquid-liquid equilibria
wave frequency; stoichiometric coefficient
film flow ratelunit width of film;
number of functional groups of kind kin mole-
thermodynamic function defined by (12-37)
cule i in UNIFAC method
residual activity coefficient of functional group
fractional current efficiency; dimensionless dis-
k in UNIFAC equation
tance in adsorption defined by (15-115); dimen-
specific heat ratio; activity coefficient sionless warped time in (1 1-2)
change (final - initial) osmotic pressure; product of ionic concentra-
solubility parameter; film thickness; velocity tions
boundary layer thickness; thickness of the lam-
mass density
inar sublayer in the Prandtl analogy
bulk density
concentration boundary layer thickness
crystal density
Kronecker delta
particle density
exponent parameter in (3-40); fractional poros-
ity; allowable error; tolerance in (10-31) true (crystalline) solid density
bed porosity (external void fraction) surface tension; interfacial tension; Stefan-
Boltzmann constant = 5.671 x lo-' w/m2 K4
eddy diffusivity for diffusion (mass transfer)
interfacial tension
eddy diffusivity for heat transfer
interfacial tension between crystal and solution
eddy diffusivity for momentum transfer
tortuosity; shear stress; dimensionless time in
particle porosity (internal void fraction)
adsorption defined by (15-116); retention time
Murphreevapor-phase plateefficiency in(10-73)
of mother liquor in crystallizer; convergence
area fraction in UNIQUAC and UNIFAC equa- criterion in (10-32)
tions; dimensionless concentration change de-
binary interaction parameter in NRTL equation
fined in (3-80); correction factor in Edmister
group method; cut equal to permeate flow rate shear stress at wall
to feed flow rate for a membrane; contact v number of ions per molecule
angle; fractional coverage in Langmuir equa-
, volume fraction; parameter in Underwood
tion; solids residence time in a dryer; root of
equations (9-24) and (9-25)
the Underwood equation, (9-28)
local volume fraction in the Wilson equation
average liquid residence time on a tray
probability function in the surface renewal theory
Maxwell-Stefan mass-transfer coefficient in a
binary mixture pure-species fugacity coefficient; association
factor in the Wilke-Chang equation; recovery
binary interaction parameter in Wilson equation
factor in absorption and stripping; volume frac-
lion; concentration ratio defined by (15-125)