list of symbols

Symbol Alternative
Units
Quantity or parameter
Symbol
A surface area m 2
a w water activity -
B nucleation rate kg -1 m -1 s -1
b breakage function m -3
C constant or coefficient -
c specific heat capacity J/kgK
D equipment diameter m
D Γ, δ diffusion coefficient m²/s
D transport tensor m²/s
d diameter or size of solids m
E energy J
F mass flux function -
f relative (normalized) drying rate -
f multi-dimensional number density -
G shear function or modulus Pa
G growth rate kg/s
g acceleration due to gravity m/s 2
H height m
H enthalpy J
H Heaviside step function -
h specific enthalpy (dry basis) J/kg
~
h h N molar enthalpy J/mol
∆ h v
specific enthalpy of evaporation J/kg
I total number of intervals -
J numerical flux function -
K constant -
K
dilatation function or bulk modulus
L length m
M m mass kg
M ~ M, M N molecular mass kg/kmol
M & W mass flow rate kg/s
m& J mass flux, drying rate kg/m²s
N number -
N molar amount mol
N & W N molar flow rate mol/s
n molar density, molar concentration mol/m³
n number density m -3
n
outward normal unit vector
n& J N molar flux mol/m²s
P power W
P total pressure kg m/s 2
p partial pressure / vapour pressure of component kg m/s 2
Q & Q heat flow rate W
q& q heat flux W/m 2
R equipment radius m
R individual gas constant J/kgK
R ~ R N universal gas constant J/kmolK
r radial coordinate m

pore (throat) radius m
S saturation -
S selection function 1/s
s boundary layer thickness m
T temperature K, °C
t time s
u velocity in z-direction m/s
u displacement m
V volume m 3
V & F volumetric flow rate m³/s
v specific volume m 3 /kg
v velocity in x-direction m/s
v general velocity vector ms -1
W weight force N
w velocity in y-direction m/s
X solids moisture content (dry basis) -
x mass fraction in liquid phase -
x particle volume in population balances m³
x lateral coordinate m
x general eulerian coordinate m
x 0 general lagrangian coordinate m
x~ x N molar fraction in liquid phase -
Y gas moisture content (dry basis) -
y lateral coordinate m
y mass fraction in gas phase -
y~ y N molar fraction in gas phase -
z axial coordinate m
Special symbols
∇
gradient operator
∇⋅
divergence operator
∆ difference operator -
Greek letters
α h heat transfer coefficient W/m²K
β k mass transfer coefficient m/s
β aggregation kernel 1/s
δ
Dirac-delta distribution
ε voidage -
ε emissivity -
ε
strain
η efficiency -
θ angle, angular coordinate rad
κ thermal diffusivity m²/s
λ thermal conductivity W/mK
µ dynamic viscosity kg/ms
µ moment of the particle size distribution
ν kinematic viscosity m 2 /s
π circular constant -

ρ density, mass concentration kg/m 3
Σ summation operator -
σ surface tension N/m
σ Stefan-Boltzmann constant for radiative heat transfer W/m 2 K 4
σ standard deviation (of pore size distribution) m
σ stress Pa
τ dimensionless time -
Φ characteristic moisture content -
ϕ relative humidity -
ω angular velocity rad
Subscripts
a
at ambient conditions
as
at adiabatic saturation conditions
bed
bed
c
cross section
c
capillary
cr
at critical moisture content
D
drag
dry
dry
dp
at dewpoint
eff
effective
eq
equilibrium (moisture content)
f
friction
g
gas (dry)
H
wet (humid) gas
i
inner
i,1,2,…
component index, particle index
i,j,k coordinate index, i,j,k = 1 to 3
in
inlet value
l
liquid (alternative: as a superscript)
m
mean value
max
maximum
mf
at minimum fluidisation
min
minimum
N
molar quantity
o
outer
out
outlet value
P
at constant pressure
p
particle
pbe
population balance equation
ph
at the interface
r
radiation
rel
relative velocity
s
solid (compact solid phase), alternative: as a superscript
S
at saturation conditions
surf
surface
V
based on volume
v
vapour, evaporation
w
water
w
wall

wb
wet
∞
at wet bulb conditions
wet
at large distance from interface
Superscripts
average, phase average
α
intrinsic phase average
v
volumetric strain
* rheological strain
* at saturation conditions
Multiple subscripts should be separated by a colon, e.g.:
Bold symbols denote vector or tensor quantities
ρ
p, dry
: density of dry particle.