UK MICE meeting at RAL

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UK MICE meeting at RAL 3 March 2004 WP2
Improving the flow performance By Rosie Cooper
Stephanie Yang, Oxford
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The natural convection model
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LH2 absorber without baffled and heat source at
60W
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Y 0m
Y 0.25m
LH2 absorber without baffled and heat source at
60W
Flow At Window
Y 0.75m
Y 0.5m
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LH2 absorber without baffled and heat source at
60W
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Global delta T 2.98K Delta T at fluid domain
1.864K (15.117K) Delta T at solid domain 1.845K
(1415.8K) Rayleigh number 2.216E11
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Max velocity 0.165m/s
LH2 absorber without baffled and heat source at
200W
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Max pressure 0.825 Pa
LH2 absorber without baffled and heat source at
200W
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Delta T at fluid domain 6.6K (16 22.6K) Delta
T at Al absorber (solid domain) 2.5K
(1416.5K) Global delta T at all domains 8.6K
Rayleigh number 7.83E11
LH2 absorber without baffled and heat source at
200W
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The idea of a baffle and how it might improve
convective cooling
Expected flow pattern of the current
Baffle
The baffle is expected to assist the convective
cooling by forcing the warm current to flow
down the side of the absorber which receives
direct cooling from the gas helium, and come up
as a cooler liquid through the centre.
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The CFD model with baffles
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Max velocity 0.1189 m/s
LH2 absorber with baffled and heat source at 200W
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Max pressure 1.47Pa
LH2 absorber with baffled and heat source at 200W
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Delta T at fluid domain 5.28K (1621.3K) Delta T
at Al absorber (solid domain) 2.8K
(1416.8K) Global delta T at all domains 7.3K
Rayleigh number 6.17E11
LH2 absorber with baffled and heat source at 200W
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Force flow cases
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Forced-flow Heat Transfer Numerical Calculations
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Forced-flow Heat Transfer Numerical Calculations
Main inlet outlet nozzle diameter is
25.8mm Branch nozzle diameter is 14.28mm (0.56)
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Forced-flow Heat Transfer Numerical Calculations
Velocity distribution
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Forced-flow Heat Transfer Numerical Calculations
Additional plots on flow patterns
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Forced-flow Heat Transfer Numerical Calculations
Temperature distribution
Inlet velocity is at 4.4m/s
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Forced-flow Heat Transfer Numerical Calculations
Pressure distribution
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Forced-flow Heat Transfer Numerical Calculations
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The question How do we improve the flow
performance without increasing the Delta P?
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Nozzle with a reduced throat area
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Graph shows plot of Reynolds Number versus nozzle
ratio, a/A.
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10m/s velocity applied at the inlet, 60W heat
source
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Remarks The results so far indicate that the
nozzle with a reduced throat area seems
promising. It gives improved flow speed and
cooling performance without increasing the delta
P inside the vessel. Our next step is to study if
similar improvement could be made by the outlet
nozzle having the same reduced throat area