Cryogenic Cooling Options for sc Applications

Transcription

Fakultät Maschinenwesen
Institut für Energietechnik
Lehrstuhl für Kälte- und Kryotechnik
Cryogenic Cooling Options for sc
Applications
Tampere sc conference
Ch. Haberstroh
Nov 5th, 2010
Outline
- Introduction
- Cooling demands
- Progress and development in cryogenic cooling
- Liquid helium technology
- Carnot considerations
- Liquid nitrogen cooling
- Cryocoolers
Gifford-McMahon
Stirling
Pulse Tube
Tampere Nov 5th, 2010
Ch. Haberstroh, Cryogenic Cooling Options
2
Professorship for Refrigeration and Cryogenics, TU Dresden
1993 – 2008
Prof. Dr. H. Quack
provisional
(before: Sulzer Cryogenics, Swiss)
Dr. rer. nat. et Ing. habil. Ch. Haberstroh
since 2010 Prof. U. Hesse, „Bitzer-Stiftungsprofessur f. Kaelte-, Kryo- und Kompressorentechnik“
ca. 12 permanent members, mostly Ph.D. students
Teaching: - Refrigeration
- Compressor Technology
- Kryo Technology
Research: - …
- …
- Helium / Hydrogen Technology; Conceptual design for large Helium Plants
He / H2 Liquefiers, Dewar optimization, Neon cooling, …
responsible for the central Helium Plant TU Dresden
co-operation with DESY, CERN, Rossendorf, GSI, BESSY, SLAC, FNAL, …
3
Cooling Task
Specification routine:
cryostat, cooling power needed
…. W @ 2 …5 ….80 K
+ …. W @ 100 K
(superconductor)
(thermal shield)
secondary demands:
- cool-down time
- duty per year (100 … 8700 h)
- efficiency expectations
- MTTF / maintenance intervals
- noise / vibration limits
ATZ Adelwitz
- available infrastructure
- …
4
Thermal sc Connection
Bath cooling
Forced cooling
Conduction cooling
e.g.: LHe 2…5 K
(supercritical,
('dry cooling',
LNe 25 … 29 K
one-phase)
indirect)
LN2 65 … 84 K
5
Cooling options:
There had been apreciable progress within the last decades …
„Kelvinator“
1928
Ice Harvest ,
Ice distribution
He-Liquefier
W. Meißner, 1956
J-T-Cryocooler 60th
(R. Radebaugh)
LOX Plant, 1910
(R. Radebaugh)
6
Helium Liquefaction
first time by Heike Kamerlingh Onnes,
Leiden University,
July 10th, 1908
Helium from monazite sand
next 15 years: exclusive LHe laboratory
discovery of superconductivity,
superfluidity, …
7
Commercial Helium Liquefier Breakthrough
Collins Liquefier: Use of Piston Expanders
1946 – 1964 about 250 units sold;
“revolution” in cryogenic research
Prof. Sam Collins,
MIT/Boston 1946
capacity: 12 … 70 l/h
8
First sc Accelerator Magnets
implemented
in the 70th
(CERN, Fermilab)
9
Helium Plants Today
Heliumverflüssiger
LHC Cold Box
18 kW @ 4.5 K
33 kW @ 50 K …75 K
+
23 kW @ 4.6 K … 20 K
+
41 g/s liquefaction
10
Theory: how to get a gas cold?
a) Joule-Thomson-Effect
b) Expansion machine
simple throttle valve, isenthalpic
expansion (without work extraction)
ΔH = O
Ù small effect (real gas property),
below inversion curve only
isentropic change of state
work is extracted from the fluid
ΔSideal = O
Ù big effect at any starting temperture
(ideal gas property)
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Expansion in the T, s diagram
Throttle
10bar
Turbine
ηs = 0.75
a) Expansion Turbine
maschine
1 state
ηs = of
isentropic change
expansion (without work extraction)
ΔSideal = O
1bar
Ù big
effect any starting temperture
(ideal gas property)
12
Basic Refrigerator Cycles
13
Liquefier
warm
He gas
often only evaporation enthalpy used (20.4 kJ/kg)
(cold gas warm-up: 1500 kJ/kg)
standard liquefier: 10 … 200 l/h
LHe
consumer
bulk liquefier: ~ 1000 … 4000 l/h
Refrigerator
heat load (e.g. superconductor)
heat
load
directly connected via transfer line + cold gas return
0.1 … 20 kW @ 1.8 …. 5 K
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Helium Expansion Turbines
axial and radial gas bearing;
operational speed
4500 s-1 typically
recently optimized;
isentropic efficiency
90th:
ηs ≈ 65 %
today: ηs ≈ 75 … 80 %
ª
50 % more cooling power !
15
Cycle Compressors / Heat Exchangers
aluminium plate-fin counterflow heat
exchangers, vacuum-brazed
oil-lubricated screw compressors
one-stage, 1 bar Æ 12 bar
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“Evolution” of Suppliers
1908 1918 1928 1938 1948 1958 1968 1978 1988 1998 2008
1908 H.K.Onnes, Leiden
ADL 500Inc
CTi
HPS KPS PSI
CPS
2002
Linde
1923 McLennan, Toronto
1925 Meißner, PTR Berlin
Sulzer
BOC
1992
1980
Air Liquide
1946 Collins, MIT
Philips
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In-house liquid helium supply
re-liquefaction:
5 … 2 kWh / lLHE
spare helium:
4 … 8 € / lLHE
Set-up for laboratory liquidhelium supply with helium recovery
Source: Air Liquide
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Maximum Efficiency
Carnot limit:
·
COPideal = Q/W = To /(Tamb – To)
for full reversible process,
perfect components, …
77 K: COPideal ≈ 0.33
(3 W/W)
4.2 K: COPideal ≈ 0.014
(70 W/W)
1.8 K: COPideal ≈ 0.006 (166 W/W)
Carnot fraction: η := COPreal / COPideal
He Plants: η ≈ 0.01 …. 0.35
e.g.: input power
Pel ≈
0.5 MW
cooling power @ 1.8 K: 200 W
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COP of Large Helium Refrigerators
500
C.O.P. [W/W @ 4.5K]
400
300
200
100
Carnot
source:
Ph. Lebrun, CERN
0
TORE
SUPRA
RHIC
TRISTAN
CEBAF
HERA
LEP
LHC
for better efficiency / less demanding cooling technology:
B Cooling / sc operation at elevated temperature level (~ 80 K) !?
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Commercial Liquid Nitrogen (LN2) Supply
excellent infrastructure,
scaled LN2 Tanks available,
no recovery necessary
Linde-Gas
Minimum price:
1 l LN2 ↔ 1 kWh electr. power
Praxair
21
In-house LN2 production
two-stage Stirling Cooler
N2 condensation / refrigerator @ 80 K
Pel = 12 kW
700 W @ 80 K
or 500 W @ 65 K
B basic technology of the 60th;
lack of progress / N2 turbine plants
Stirling BV, Eindhoven
22
Cryocooler I: Gifford-McMahon
W. Gifford + H. McMahon, 50th
- Standard-Cyclecompressor (50/60 Hz)
- flex. lines
- one/twostage coldhead (1…2 Hz)
typical:
3 … 20 W @ 20 K
+ 20 … 100 W @ 80 K
+ reliable, moderate costs
+ sales 20 000 units / yr
-
compressor 30 … 80 kg
-
coldhead vibration
-
modest efficiency (0.7 … 1.4 % 'Carnot' @ 80 K)
COOLPOWER, Oerlikon-Leybold
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G-M – Cooler AL600
CryoMech:
www.cryomech.com
580 W @ 80 K
Pel ≈ 13 kW
i.e. 11%
Carnot fraction !
maintenance interval: 10 000 h
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Cryocooler II: Stirling Coolers
Stirling: vintage cooler,
subject to continuous improvement
+ moderate costs (600 … 3000,- €/unit)
+ small, lightweight
+ technically mature (~ 100 000 units
manufactured to date)
+ turnover 20 000 units / yr.
- limited lifetime (dry sealing)
- intrinsic vibration
now:
flexure bearing
Rotory Stirlingcooler
1 W @ 80 K, Pel ≈ 50 W
I. Rühlich, AIM Heilbronn
25
50 000
Rotary
Cooler
Reliability MTTF [h]
40 000
Linear
Cooler
1st.
Gen
2000
30 000
20 000
10 000
Flexure
Bearing
Cooler
Next Gen
+
Pulse Tube
coldfinger
2nd. Gen
+
Stirling
coldfinger
Lifetime of
Stirling
Cryocoolers
I. Rühlich,
AIM Heilbronn
2nd. Gen
2002
SL150
1st.
Gen
(HD1033,
SC100)
Small
Rotary
newest
design
1st
Gen
1993
0 000
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Stirling
Cryocooler,
Example
Produkt Line
I. Rühlich,
AIM Heilbronn
Pulse
Tube
Stirling
SX095
SL100
SL150
SX040
SF070
SF100
SF400 PT
Cooling Capacity at 80K
1.3 W
1.5 W
2.5 W
0.7 W [95K]
0.8 W
2W
2W
Input Power Pin
45 W
60 W
85 W
35 W
35 W
60 W
100 W
Weight
1.0 kg
2.0 kg
2.3 kg
0.7 kg
1.0 kg
1.6 kg
3.4 kg
Reliability MTTF
>25.000 h > 10.000 h > 8.000 h
>25.000 h
>20.000 h >20.000 h > 50.000 h
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Cryocooler III: Pulse Tube
= Stirling Cooler without solid displacer (gas column only)
discovered by chance; since ~ 1985 systematic R & D
Modifications: basic, orifice, double-inlet, inertance tube Pulse Tube
Geometry: in-line / coaxial / U-shaped
To = 80 K … 4 K … 2.35 K (!)
+ no moving cold part, no wear, simple layout
+ no vibrations / no elektromagnetic noise
+ high efficiency
- short history, limited series-production readiness
- orientation-dependant; limited scalability
28
Pulsrohrkühler
CryoMech PT60
60 W @ 80 K
Pel ≈ 3.3 kW
maintenance-free
www.cryomech.com
(Adsorber change
after 20 000 h)
29
Summary

Appreciable progress in cooler technology during the last decades

2 x chicken-and-egg problem:
a)
still some missing capacity / temperature level combinations
b)
cooler availability strongly dependent on turnover figures

Cryogenic cooling necessarily will stay demanding and expensive

There is a variety of available cooling options
– no sc application should fail because of missing
cryogenic cooling technology
30

Cryogenic Cooling Options for sc Applications

Transcription

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