Endress+Hauser Deltatop DP71B, Руководство по эксплуатации

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Deltatop DP71B, DP72B, DP73B Appendix
Hauser 47
9.2 Flow calculation
According to the continuity law derived by Bernoulli and the energy equation, the static pressure in
the flow plus the dynamic pressure is equal to a constant throughout the flow:
p
stat
+ p
dyn
= const.
From this law, the following flow equations can be derived:
9.2.1 Volumetric flow for gases under standard conditions
9.2.2 Volumetric flow for gases under operating conditions
9.2.3 Mass flow for gases and steam
9.2.4 Mass flow for liquids
9.2.5 Volumetric flow for liquids
9.2.6 Definition of the symbols
Symbol Quantity Unit
Δ
p Differential pressure at the probe profile Pa
ρ
n
Medium density at standard conditions kg/m
3
b
Medium density at operating conditions kg/m
3
A Cross-sectional area of the pipe m
2
b Width of the probe profile perpendicular to the flow direction m
k k-factor of the Pitot tube 1
κ
Isentropic exponent of the gas
1)
1) The isentropic exponent is: 1.66 for monoatomic gases; 1.4 for diatomic gases; 1.3 for triatomic gases
1
P
b
Operating pressure Pa
P
n
Absolute pressure of the gas at standard conditions Pa
Q
m
Mass flow kg/s
Q
v
Volumetric flow m
3
/s
Q
vn
Volumetric flow at standard conditions m
3
/s
T
b
Temperature of the gas at operating conditions K
T
n
Temperature of the gas at standard conditions K
Z
b
Real gas factor at operating conditions 1
Z
n
Real gas factor at standard conditions 1
ε
Expansion factor 1
2 p
D
r
Q = k A
e
vn
P
b
Z T
n n
P
n
Z T
b b n
2 p
D
r
Q = k A
e
v
b
2 p
D r
m
k A
e
b
Q =
2 p
D r
m
k A
b
Q =
2 p
D
r
Q = k A
v
b