radio frequency cavity air cooling
DESCRIPTION
Radio Frequency Cavity Air Cooling . General problem. New Radio Frequency cavity developed in BE dep. 2 coils dissipating 650W each by joule effect. Define cooling air mass flow to keep the coils colder than 80˚C. Improve cavity shape to reduce hotspots. Development time: about 1 month. - PowerPoint PPT PresentationTRANSCRIPT
Radio Frequency Cavity Air Cooling
A.Romanazzi 1CFD team supports CERN development 19 May 2011
• New Radio Frequency cavity developed in BE dep.
• 2 coils dissipating 650W each by joule effect.
• Define cooling air mass flow to keep the coils colder than 80˚C.
• Improve cavity shape to reduce hotspots.
• Development time: about 1 month
General problem
A.Romanazzi 2CFD team supports CERN development 19 May 2011
Estimate mass flow in Nominal Conditions
• Thermal conductivity of the rings: 7 W/(m °C)
• Power dissipation per ring : 650 W continuous ≈1/r2
• Range of tested air mass flows: 0.1 - 0.5 kg/s
90 mm
25 mm
20 mm
A.Romanazzi 3CFD team supports CERN development 19 May 2011
Mesh and numerical models• Air: compressible ideal gas model• K-Ԑ Two Layers Turbulence model• Buoyant flow• Thermal conduction over the supports and the box are neglected
CFD team supports CERN development 19 May 2011
4A.Romanazzi
Gas domain• Core Polyhedral Mesh• 10 layers cells
“boundary layer”• Extrusion on outlet sideSolid domain• Core Polyhedral Mesh
0.1 0.2 0.3 0.4 0.540
50
60
70
80
90
100
110
120
130
140
Rings Temperature
T max solid [C]
T aver solid [C]Air mass flow [Kg/s]
Tem
pera
ture
[C]
Nominal ConditionsRings temperature VS air mass flow
Rings’ temperature for 0.3 kg/s case.
A.Romanazzi 5CFD team supports CERN development 19 May 2011
Flow at Nominal Conditions
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
500
1000
1500
2000
2500
3000
3500
Pressure Drop [Pa]
ΔP [bar]
Polynomial (ΔP [bar])
Air mass flow [kg/s]
Velocity magnitude maps on middle section0.3 kg/s case
A.Romanazzi 6CFD team supports CERN development 19 May 2011
Studied Modified Geometries
V.3 V.4 V.5 V.6 V.7
Compromise between reducing pressure drop and making the most uniform the Heat transfer coefficient on the coils’ surfaces.
A.Romanazzi 7CFD team supports CERN development 19 May 2011
Case: 0.3kg/sV.3 V.4 V.5 V.6 V.7
A.Romanazzi 8CFD team supports CERN development 19 May 2011
0.1 0.2 0.3 0.4 0.545
55
65
75
85
95
105
115
Rings Max Temperature
v1 averv3 averv4 averv5 averPower (v5 aver)v6 averPower (v6 aver)v7 averPower (v7 aver)
Air mass flow [kg/s]
Tem
pera
ture
[C]
0.1 0.2 0.3 0.4 0.50
1000
2000
3000
4000
5000
6000
Pressure drop
v1v3v4v5Power (v5)v6Power (v6)v7Power (v7)
Air mass flow [kg/s]
Pres
sure
[Pa
]
Temperature VS Pressure Drop
A.Romanazzi 9CFD team supports CERN development 19 May 2011
Final Cavity Layout
• From treated cases we learn that:– Coils’ supports interfere
with air flow/heat transfer
– No grills: lower pressure drop
– Cavity corners have to be “closed”
Version 9
A.Romanazzi 10CFD team supports CERN development 19 May 2011
HTC: lower absolute value but more uniform(depends only on air flow pattern – independent from solid properties)
V.3 V.4 V.9V.7
A.Romanazzi 11CFD team supports CERN development 19 May 2011
Case: 0.3kg/sV.3 V.4 V.9V.7
A.Romanazzi 12CFD team supports CERN development 19 May 2011
0.1 0.2 0.3 0.4 0.560
70
80
90
100
110
120
130
140
Rings Max Temperature
v1 maxv3 maxv4 maxv7 maxv9 max
Air mass flow [kg/s]
Tem
pera
ture
[C]
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
1000
2000
3000
4000
5000
6000
Pressure Drop
Air mass flow [kg/s]
Pres
sure
[Pa
]
A.Romanazzi 13CFD team supports CERN development 19 May 2011
ConclusionsOur first target was to estimate a mass flow able to
guarantee T<80˚C: obtained with a mass flow of 0.3kg/s
Secondly target was to uniform the HTC over the coils’ surface to prevent from hot-spots and lower the pressure drop across the system: between the studied geometries “version 9” is the best compromise between those conditions.
Experimental test of the cavity are going to be performed in the next future to validate the cavity and the simulations.
A.Romanazzi 14CFD team supports CERN development 19 May 2011
Thank you for your attention!
CFD team supports CERN development 19 May 2011
15A.Romanazzi