Environmental Engineering Reference
In-Depth Information
Case3:VariableCavernPressureand
ConstantTurbineInletPressure
In the third case we consider, the air recovered from storage is throttled from
the reservoir pressure p
s
to the hp turbine inlet pressure p
1
such that the
mass flow and expansion work output are constant in time. As in case 1,
the integral representing the mechanical work in turbine expansion can be
reduced to a simple time average, but in this case, the net air mass with-
drawn from storage is a function of the storage pressure fluctuation over the
range p
S2
to
p
S1
:
∆
m
t
m
m
m
=
A
1
+
F
(5.31)
T
A
1
k
S
V p
RT
V p
RT
V p
RT
−
p
p
∆
m
=
S S
2
−
S S
1
=
S S
2
S
1
1
(5.32)
A
S
2
S
1
S
2
S
2
Substituting these into Equation (5.30) yields
k
−
1
1
2
E
V
α
M p
RT
+ −
p
p
−
p
p
k
k
S
2
GEN
=
W S
2
β
b
S
1
1
1
(5.33)
S
S
2
2
S
2