Transcript C3F8 cooling @ NIKHEF Design Compare Does it work?

C3F8 cooling @ NIKHEF
Design
Compare
Does it work?
5/27/2016
Auke-Pieter Colijn
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Two-stage cooling
• Standard cooling
– C3F8 coolant only
• Dual-system @ NIKHEF:
– R404A primary coolant
– C3F8 secondary coolant
• Cheap & easy ……..
– Do not need oil-less compressor
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Auke-Pieter Colijn
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FRONT VIEW
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REAR VIEW
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My favorite tools
snoop
P sensors
T sensors
Freon “doggy”
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R404A
Pressure control
Main evaporator
1) Regulate C3F8 T with
R404A evaporator P
Expansion valves
2) Expansion valves
regulate P [0-3kW@-25C]
T sensor
Hot gas bypass
3) Explain sub-cooler in a
bit
T sensor
Sub-cooler
Compressor
H2O condenser
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Primary cooling: R404A
A-B: Compress R404A
LIQUID
P [bar]
B-C: Liquefy hot gas in H2O
condenser
B
C
A
D
GAS+LIQUID
D-A: Evaporate R404A. Heat is
absorbed from C3F8
GAS
Enthalpy [J/g]
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C-D: R404A expansion
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1.dH = dQ
2. P = flow*dH
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C3F8 system for Testbox
Main evaporator= C3F8 condenser
C3F8
10-12 bar P control
HEAT LOAD
a.k.a. detector
R404A
C3F8
Sub-cooler
Restrictors
R404A
Pump
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Auke-Pieter Colijn
Can adjust C3F8 flow!
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C3F8 Cooling@CERN
LIQUID
P [bar]
D
C
B
1. A-B: compression
E
A
2. B-C: condensing
3. C-D: sub-cooling w. heat
exchanger on outlet
4. D-E: expansion
GAS+LIQUID
GAS
5. E-A: absorb heat from
detector (+ sub-cool inlet)
Enthalpy [J/g]
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Auke-Pieter Colijn
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C3F8 Cooling@NIKHEF
LIQUID
1. A-B: condensing
P [bar]
D
2. B-C: sub-cooling
3. C-D: pump to 12bar
4. D-E: expansion
E
C B
5. E-A: absorb heat from
detector
A
What is BAD about point E?
GAS+LIQUID
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GAS
Enthalpy [J/g]
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C3F8 Cooling@NIKHEF
LIQUID
D
E
P [bar]
1. A-B: condensing
2. B-C: sub-cooling
F
3. C-D: pump to 12bar
A
C B
4. D-E: heating
5. E-F: expansion
6. F-A: absorb heat
GAS+LIQUID
GAS
Enthalpy [J/g]
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Run it!
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Run: Temperature
Start-up
Run
Warm-up
1. I want -10C, I get -10C
2. Need to study fluctuations
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Run: Pressure
Start-up
Run
Warm-up
Inlet pressure = 11bar
Return pressure = 2.8bar = -10 C
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Start-up problems
– Lots of leaks
– Broken R404A expansion valve
– Controller (unwired)
– Cooling water stability
– No manual: safety/operations
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Auke-Pieter Colijn
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To do
• Adjust controller: limit temperature fluctuations
• Adjust pressure: 12 bar C3F8
• Adjust flow: each disk circuit
• New pump: need one without leaks
• Heater element: avoid sub-cooled cooling
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Summary
• Cooling plant @ NIKHEF
1. Different design
2. Works
3. Make final adjustment
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