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C.KotnigFCC Design Meeting New Beam Screen Design 3 Small CB C10 Small CB O4 Big CB C8Big CB O4 T ≈ K Antechamber T ≈ 1 K Thermal comparison of the examined designs Higher temperature range available for extracting the heat → Less mass flow → Less pressure drop → Less exergy losses
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C.Kotnig FCC Design Meeting 12.11.2015
FCC Beam Screen cooling
Claudio Kotnig
C.Kotnig FCC Design Meeting 12.11.2015 2
Content
1. New Beam Screen Design2. Beam Screen Cooling – Sector design
a) Basic hydraulic schemeb) Header and magnet string design
3. Modifications of the basic hydraulic scheme4. Transient modes: Beam Injection5. Summary
C.Kotnig FCC Design Meeting 12.11.2015 3
New Beam Screen Design
Small CB C10
Small CB O4
Big CB C8
Big CB O4
DT ≈ 2 - 3 K
Antechamber
DT ≈ 1 K
Thermal comparison of the examined designs
Higher temperature range available for extracting the heat→ Less mass
flow→ Less pressure drop→ Less exergy losses
C.Kotnig FCC Design Meeting 12.11.2015 4
New Beam Screen Design
Small CB C10
Small CB O4
Big CB C8
Big CB O4
ACap ≈ 68.4 mm2
ACap ≈ 26.2 mm2
ACap ≈ 9.6 mm2
ACap ≈ 1.8 mm2
Atot ≈ 274 mm2
Atot ≈ 105 mm2
Atot ≈ 77 mm2 Atot ≈ 18 mm2
Antechamber
ACap ≈ 57.6 mm2Atot ≈ 115 mm2
dhyd ≈ 6.14 mm
dhyd ≈ 2.81 mm
dhyd ≈ 3.5 mm dhyd ≈ 1.5 mm dhyd ≈ 6.03 mm
Hydraulic comparison of the examined designs
Hydraulic performance should be between Big CB O4 and Small CB O4
C.Kotnig FCC Design Meeting 12.11.2015 5
Large controlling effort Investment costs Down time due to component failure
≈
≈
≈
Beam Screen Cooling – Sector design
FCC sector design:
1. Control Valves+ Minimizing total mass flow+ Individual control of single magnet strings+ High efficiencies and stable operation in non-
nominal modes
→ valves, but minimize necessary amount
→ Parallel flow scheme with possible advantages compared to counter flow scheme, if no valves would be used
2. Flow direction → counter flow scheme3. Assembly
scheme+ Large temperature range
available Variable compressor inlet conditions + High pressures in the magnet strings Large valves necessary
+ High supply pressures → smaller pressure losses+ High supply pressures → smaller pressure ratios
4. Supply pressure→ supply pressure 50 bar→ assembly scheme HX1 - C – HX2 – MS - V
C.Kotnig FCC Design Meeting 12.11.2015 6
Beam Screen Cooling – Sector design
Pressure drop in beam screen and headers is a crucial influence quantity for the necessary electrical power
Pressure losses can be reduced with• increasing header
diameter→ high investment costs and
necessary space• shorter magnet strings → many valves necessary
Influence on the exergetic efficiency by variation of these parameters on the hydraulic schemes?
• Supply pressure p0 = 50 bar• Isentropic efficiency of the (cold) compressor hs = 0.7
C.Kotnig FCC Design Meeting 12.11.2015 7
Beam Screen Cooling – Sector design
Exergetic efficiency z vs. header diameter dH for 1, 4 & 7 magnets per MS
C.Kotnig FCC Design Meeting 12.11.2015 8
Modifications of the basic hydraulic scheme
Example: Distribution of pressure losses in magnet strings (7 magnets)
Installing a bypass at the last MS
• increases the total mass flow
• deacreases the basic pressure drop in the last magnet string
MS inlet temperature increases due to thermal shielding of the supply header
mBP = 0.43 kg/s
C.Kotnig FCC Design Meeting 12.11.2015 9
Exergetic efficiency z vs. bypass mass flow mBP for 1, 4 & 7 magnets per MS
Modifications of the basic hydraulic scheme
zmax zmaxzmax
C.Kotnig FCC Design Meeting 12.11.2015 10
Modifications of the basic hydraulic scheme
Example: Distribution of pressure losses in magnet strings (7 magnets)
→ No thermal shielding tasks for the supply header
Basic (minimal) pressure drop increases with MS inlet temperature
→ MS inlet temperature low and almost constant
Basic: Dp0 ≈ 8 bar
Bypass: Dp0 ≈ 5.5 bar
RH-Shield: Dp0 ≈ 4 bar
C.Kotnig FCC Design Meeting 12.11.2015 11
Modifications of the basic hydraulic scheme
Exergetic efficiency z vs. header diameter dH for 1, 4 & 7 magnets per MS
C.Kotnig FCC Design Meeting 12.11.2015 12
Modifications of the basic hydraulic scheme
Warm compressor cycle (TU Dresden)
• Depending on pressure drop in the sector, the necessary power consumption including the Nelium-Cycle, could be lower than in a cold compressor cycle
• A warm compressor is less prone to failure and easier to handle
• A warm compressor could be used for cool-down and warm-up tasks
• A warm compressor could have advantages regarding load changes (e.g. inserting the beam after working a long time in standby mode, etc. )
Warm compressor cycle
TaCold compressor cycle
Neliu
m
cycle
Neliu
m
cycle
C.Kotnig FCC Design Meeting 12.11.2015 13
Exergetic efficiency z vs. header diameter dH for 1, 4 & 7 magnets per MS
Modifications of the basic hydraulic scheme
C.Kotnig FCC Design Meeting 12.11.2015 14
hs = 0.7 (cold compressor)
hs = 0.83 (warm compressor)
hth = 0.42 (Nelium cycle)
Modifications of the basic hydraulic scheme
Beam screen sector cycle + Nelium cycle
Shie
ld
1M
Shie
ld
4M
Shie
ld
7M
Bypa
ss
4M
Bypa
ss
7M
Bypa
ss
1M
Basic
1M
Basic
7M
Basic
4M
1 MW ≙ 36,000,000 CHFin 10 years of FCC operation
1)2)
3)
C.Kotnig FCC Design Meeting 12.11.2015 15
Modifications of the basic hydraulic scheme
1 2 3# magnets per string 4 7 7# valves 138 79 79total mass flow 5.68 kg/s 5.08 kg/s 5.08 kg/sbypass mass flow 0.15 kg/s (≈ 2.6
%)- -
temperature last MS inlet
44.6 K ≈ 40 K ≈ 40 K
pressure drop last MS 2.02 bar 3.84 bar 3.84 barpressure drop / ratio 2.8 bar / 1.06 4.6 bar / 1.10 4.6 bar / 1.10total power consumption
8.3 MW 8.4 MW 9.2 MWadditional piping yes yes yeswarm compressor benefits
no no yes
temperature HX inlet 60.0 K 62.5 K 62.5 K
?
?
C.Kotnig FCC Design Meeting 12.11.2015 16
Transient modes: Beam injection
Similar increase of current like in the LHC → standby to nominal operation in 27 minutes
in
nom
nom
in
nom
redpp
TT
m
mm
in
incor
pTmm 101325
15.288
C.Kotnig FCC Design Meeting 12.11.2015 17
Transient modes: Beam injection
Fast increase of heat to extract (especially at the end of the injection process)→ during normal physic’s runs the working point of the
compressor shall be kept constant artificially
Only during longer breaks, the load on the compressor shall be decreasedStarting physic’s runs again → reach working point by closing valves before magnet ramping starts
Tin = const.pin = const.m = const.
C.Kotnig FCC Design Meeting 12.11.2015 18
Summary
SummaryThe pressure drop generated in the sector is the crucial quantity for the necessary electrical power – the design of the hydraulic scheme is decisive for the final pressure drop.
Based on the actual sector design, hydraulic schemes with a cold compressor are the better choice w.r.t. the power consumption.Warm compressors have advantages like multipurpose usage and easier handling.The investigation of transient processes could bring the choice regarding the type of used compressor to a head, if one concept clearly is superior during transient modes.
The separate shielding scheme is the preferable choice to minimize the necessary power consumption for cooling magnet strings of reasonable lengths.
C.Kotnig FCC Design Meeting 12.11.2015
19
Thank you very much for your attention
C.Kotnig FCC Design Meeting 12.11.2015 20
New Beam Screen Design
New Beam Screen Design developed by the VCS-Group at CERN
• Shield (Antechamber)
• Beam Tube
• Capillaries
• Copper layer(s)
Cold Bore
41
C.Kotnig FCC Design Meeting 12.11.2015 21
New Beam Screen Design
Heat loads affecting the Beam Screen:
• 28.4 W/m (synchrotron radiation)
• 3 W/m (resistance image current)
o Small dispersion angle (≈ 10º)
o Large component in axial direction
→ parts affected by the synchrotron radiation depend on the reflection and the distances between the stabilizing ribs
o Only one direction
o Heat transition via weld contacts
C.Kotnig FCC Design Meeting 12.11.2015 22
New Beam Screen Design
≈ 56 K
< 41 K
40 K
Temperature difference < 1 K(former designs: ≈ 2 - 3 K)
→ Larger temperature difference available
• less exergy losses
• less mass flow
C.Kotnig FCC Design Meeting 12.11.2015 23
Beam Screen Cooling – Sector design
Solutions for provide compressor with constant inlet conditions
Second HX
Bypass
+ Low investment costs and necessary space
High investment costs and necessary space
+ Possibility of using different temperature levels
Temperatures clearly below 40 K necessary
C.Kotnig FCC Design Meeting 12.11.2015 24
Basic Beam Screen Cooling System
C.Kotnig FCC Design Meeting 12.11.2015 25
Modifications of the Basic Beam Screen Cooling System
C.Kotnig FCC Design Meeting 12.11.2015 26
Modifications of the Basic Beam Screen Cooling System
C.Kotnig FCC Design Meeting 12.11.2015 27
Modifications of the Basic Beam Screen Cooling System