MTA Cryostat
& cooling loop design
Christine Darve
Fermilab/Beams Division/ Cryogenic Department/ Engineering and Design Group
Preparation of the Mucool/MICE review
02/11/03
BD/Cryogenic Department
MTA cryo-system - Specifications
Remove up to 150 Watt of energy loss from LH2
P= 1.2 atm,
T= 17 K
Dr < 5%
DT~ 1 K (could be 3 K)
5
Density change / dens. LH2 @ 17 K (%)
FERMILAB
4
3
2
1
0
-1
14
15
16
17
18
19
20
21
-2
-3
-4
-5
Temperature of LH2 (K)
Safety requirements:
1.
2.
3.
4.
5.
CD
“ Guidelines for the Design, Fabrication, Testing, Installation and Operation
of LH2 Targets–20 May 1997”, Fermilab by Del Allspach et al.
Fermilab ES&H (5032),
code/standard ASME, NASA,
NEC (art 500)
CGA
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB
BD/Cryogenic Department
MTA cryo-system - Materials
1. Caltech LH2 pump


Max LH2 mass-flow = 450 g/s (0.12 MPa, Tin=17 K)
DP total < 0.36 psig
References :
1.
“A high power liquid hydrogen target for parity violation
experiments”, E.J. Beise et al., Research instruments & methods in
physics research (1996), 383-391”
2.
“ MuCool LH2 pump test report”, C. Darve and B. Norris, (09/02)
2. Cryo department refrigeration system

Max He mass-flow = 27 g/s (0.2 MPa , Tin=14 K)

DT=3 K for 450 W (17 K, 0.12 MPa)
Reference :
1.
CD
“Results of the MuCool Expander Flow Tests Performed at the Meson Cryogeni Test Facility”, A.
Martinez and A. Klebaner, (12/02)
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB Part V – A look at the Hydrogen Proposal
BD/Cryogenic Department
Cryo-system design- Pressure drop calculation
RECALL from Internal review (09/24/02)
If m=450g/s and 32 nozzle dia. = 0.6”
then Maximum allowable DP = 0.364 psi
Total DP calculated=> 0.203 psi
0.011
psi
0.036 psi
0.011 psi
0.027 psi
0.031 psi
0.078 psi
0.011 psi
Will a velocity at the nozzle equal to 2.5 m/s be enough for ionization cooling?
CD
MTA Cryostat and cooling loop design
February 11 2003
MTA cryo-system – Cryoloop Design
FERMILAB
BD/Cryogenic Department
mass flow
DP
Given geometry,
Power and
nozzle distribution
Velocity at nozzle
Heat transfer coeff.
DT
Flow Simulation by Wing Lau/ Stephanie
Yang/ Charles Holding (Oxford)
Oxford studies:
CD
1.
Simulate the current MTA manifold geometry
2.
Simulate beam at 150 W (volume, ø10mm (3 sigma gaussian))
3.
Calculate heat transfer coefficients and temperature
distribution for MTA conditions (DV ~ 0.5 m/s – 4 m/s)
MTA Cryostat and cooling loop design
February 11 2003
MTA cryo-system – Cryostat Design
FERMILAB
BD/Cryogenic Department
1. Cryostat assembly:






CD
2.
Vacuum vessel: MAWP=25 psig; SS,
IPS 16 Sch10, IPS 50 Sch10
 Dome (SS, 10 mm)
 Plate (SS, 10 mm)
Thermal shield +MLI (Al, Mylar)
3.
Piping (SS, IPS 1, 2)
Helium buffer(SS,f 3)
Vacuum window(Al)
Safety devices (see internal review)
Heat exchanger assembly

Coil (copper, f 0.55in)

Outer shell (SS, IPS6)
LH2 pump assembly

LH2 pump and shaft with foam

Motor outer shield
MTA Cryostat and cooling loop design
February 11 2003
Part V – A look at the Hydrogen Proposal
FERMILAB
BD/Cryogenic Department
To meet the standard
RECALL from Internal review (09/24/02)
Pressure relief valve – LH2 : II C 4 a (iii)
Relief pressure (10 psig or 25 psid)
Sized for max. heat flux produced by air condensed on the LH2 loop at 1 atm.
2 valves ACGO
ASME code
Capacity = 52 g/s
=> 0.502 in2
Redundant
Pressure relief valve – Insulation vacuum : II D 3
MAWP (15 psig internal)
Capable of limiting the internal pressure in vacuum vessel to less than 15 psig
following the absorber rupture (deposition of 25 liter in the vacuum space)
Vapor evaluation q= 20 W/cm2
Take into account DP connection piping and entrance/exit losses
3 parallel plates (FNAL design)
ASME code
Capacity = 197 g/s
=> 2”
Redundant
Relief system must be flow tested
CD
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB
BD/Cryogenic Department
MTA cryo-system – Cryostat Design
4. Absorber assembly:


Ed Black/Wing Lau windows and manifold design
Interface of the systems
 Bimetallic junction
 Indium Doubled-seal
5. Supporting system

G10 spider
6. Instrumentation





P: Penning, DP
T: Cernox
Flowmeter, Heater
Valve (elec, pneum, manual..)
Turbomolecular pump (N2 guard)
Minimum spark energies for ignition of H2 in air is 0.017 mJ at 1 atm, 300 K
Lower pressure for ignition is ~1 psia (min abs. 0.02 psia // 1.4 mbar)
CD
MTA Cryostat and cooling loop design
February 11 2003
MTA cryo-system – Conclusions
FERMILAB
BD/Cryogenic Department
Cryostat design Focus :

Final cooling system

Implementation of the vacuum windows

Heater implementation (Helium side)

Supporting system

Instrumentation implementation
Cooling loop Focus:
 Thermo-hydraulic behavior inside LH2 absorber for which DT=1 K:
geometry and nozzle, power distribution, mass flow ==>DP
 Validation of optimization to DT and DP as specified
CD
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB
BD/Cryogenic Department
MTA cryo-system – Questions
1. Sealing for vacuum window: Teflon O’ring, Indium sealing, copper gasket (Radiation
hardness)
2. Cryopumping (turbo-molecular pump, thermal shield)
3. Distribution of RFs and magnets around cryostat: interface atmosphere or vacuum
behind cryostat vacuum window
4. Supporting system and absorber position in magnet
5. Who design cryostat support in hall?
6. Absorber Instrumentation routing and port
7. …..
CD
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB
BD/Cryogenic Department
Part V – A look at the Hydrogen Proposal
Process and Instrumentation Diagram
RECALL from Internal review (09/24/02)
CD
MTA Cryostat and cooling loop design
February 11 2003
FERMILAB
BD/Cryogenic Department
Part IV – A look at the Windows and Absorber Vessel
LH2 Manifold absorber (by E. Black)
RECALL from Internal review (09/24/02)
CD
MTA Cryostat and cooling loop design
February 11 2003