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Critical Heat Flux 02
1
A boiling channel has operating characteristics listed below.
Assuming the heat flux profile is
⎟
⎠
⎞
⎜
⎝
⎛
′
′
=
′
′
H
z
q
z
q
π
sin
)
(
0
Determine the critical power ratio in the channel using both the HenchLevy and CISE4 correlations.
You may
assume for the HenchLevy correlation, that the critical power corresponds to the condition where the minimum
critical heat flux ratio is one.
The CISE4 critical boiling length correlation is
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
+
=
b
L
aL
D
D
x
crit
crit
e
h
crit
where
h
D
is the heated diameter and
e
D
is the equivalent diameter for the channel.
The parameters in the CISE
correlation are:
⎪
⎪
⎩
⎪
⎪
⎨
⎧
−
×
>
−
−
×
≤
−
×
+
=
−
−
3
3
/
1
3
3
4
)
/
1
(
3375
)
1000
/
(
/
1
)
/
1
(
3375
)
/
1
(
10
481
.
1
1
1
c
c
c
c
P
P
G
G
P
P
P
P
G
G
P
P
a
4
.
1
4
.
0
)
1
/
(
199
.
0
GD
P
P
b
c
−
×
=
G = kg/m
2
s
D = m
P = MPa
P
c
= Critical Pressure (Mpa)
L
crit
= m
Problem Data
Maximum Heat Flux
354,000 Btu/hrft
2
Channel Mass Flux
1.13 x 10
6
lbm/hrft
2
Rod Pitch
0.640 inches
Rod Diameter
0.493 inches
Channel Pressure
1000 psia
Channel Height
148 inches
Inlet Temperature
532 F
SOLUTION
The critical power ratio for the channel is
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View Full DocumentCritical Heat Flux 02
2
()
0
0
0
0
0
0
sin
sin
q
q
dz
H
z
q
dz
H
z
q
q
q
CPR
crit
H
H
crit
crit
′
′
′
′
=
⎟
⎠
⎞
⎜
⎝
⎛
′
′
⎟
⎠
⎞
⎜
⎝
⎛
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 Fall '08
 Doster

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