Symbol Physical Quantity | Unit | |
A | area | m2 |
a | constant, 3414 Pa K/m | Pa K/m |
α | contact angle | ° |
B0 δ | specific permeability water vapour permeability (unit | m2 |
dependent on potential) | kg/m s Pa or m2/s | |
D | diffusion coefficient (unit dependent | |
on potential) | kg/msPa or m2/s | |
d | material thickness | m |
fRi | temperature factor | - |
G | amount of moisture | kg/s |
g | moisture flow | kg/m2s |
g | gravitational acceleration, 9.81 m/s2 | m/s2 |
η | air-dynamic viscosity (approx. | |
18.1×10-6 Pa s at 20 °C) | Pa s | |
Ψ | driving potential (e.g., vapour pressure or concentration) | |
h | height | m |
k | transport coefficient (dependent on | |
driving potential) | ||
L | air volume as volume flow rate | m3/s or m3/h |
λ | thermal conductivity | W/m·K |
m | mass | kg |
M | molar mass | kg/mol |
n | porosity | - |
n | air exchange rate | h-1 |
μ | water vapour diffusion resistance factor | - |
ν | water vapour content or water vapour | |
concentration | (kg/m3) | |
p | pressure | Pa |
p | force | N |
R | thermal insulance factor | m2K/W |
R | universal gas constant, 8.314 J/mol K | J/mol K |
Rv | gas constant for water vapour, 461.4 J/kg K | J/kg K |
r | pore radius | m |
ρ | specific gravity or density | (kg/m3) |
σ | surface tension | N/m |
T | absolute temperature | K |
θ | temperature | °C |
V | volume | m3 |
Z | water vapour diffusion resistance factor (Z-value) | GPa s m2/kg |
Suffix | |
|---|---|
i | inside |
l. | air |
m. | saturated |
sat | saturated |
ν | water vapour content |
tot | total |
p | pressure |
u. | outside |
v. | water vapour |
tot | total |