Environmental Engineering Reference
In-Depth Information
f
driving force for drying (=
w
−
w
e
)
[kg]
kg
−1
]
h
mass-specific enthalpy
[J
m
−2
K
−1
]
h
heat transfer coefficient
[W
kg
−1
]
h
fg
heat of vaporization
[J
s
−1
]
k
mass transfer coefficient
[m
L
size of screen opening
[mm]
Le
Lewis number (= Sc/Pr)
[
-
]
M
moisture content
[wt%]
mol
−1
]
MW molecular weight
[kg
m
mass
[kg]
M
cu
cumulative fraction of particles by mass <
d
p
[
-
]
p
pressure or partial pressure
[bar]
Pr
Prandtl number (=
ν
/a =
η
c
p
/
λ
)
[
-
]
Q
heat flow supplied or extracted
[W]
m
−2
s
−1
]
R
drying rate per unit area
[kg
Re
reynolds number (=
ρ
vd/
η
)
[
-
]
mol
−1
K
−1
]
R
u
universal gas constant
[J
Sc
Schmidt number (=
ν
/D)
[
-
]
T
temperature
[K]
t
time
[s]
[m
3
]
V
volume
s
−1
]
v
velocity
[m
W
power
[W]
w
water content on a mass basis
[kg]
w
i
mass fraction of particles with size
d
p,i
[
-
]
ε
voidage
[
-
]
η
dynamic viscosity
[Pa
s]
[m
2
s
−1
]
ν
kinematic viscosity
m
−3
]
ρ
density
[kg
ϕ
relative humidity
[
-
]
s
−1
]
φ
m
mass flow
[kg
χ
porosity
[
-
]
ω
humidity ratio
[
-
]
Subscripts
a
air
app
apparent
ar
as received basis
b
biomass
c
constant-rate period, critical
cv
control volume
d
dry
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