Cryogenic Engineering, CERN, March 2004 Cryogenic Engineering CERN, March 8 - 12, 2004 Temperature...

Cryogenic Engineering, CERN, March 2004

KKCryogenic Engineering

CERN, March 8 - 12, 2004

• Temperature reduction by throttling and mixing

• Temperature reduction by work extraction

• Refrigeration cycles: Efficiency, compressors, helium, hydrogen

• Cooling of devices


KK

T 1warm

T Uwarm

T 2kalt

T 0kalt

Q 0

.Q.

Abb. 1.2.1 Von selbst ablaufender Prozeß Abb.1.2.2 Aufgabe der Kältetechnik

cold cold

Process running by itself Process needing driving power

Mankind had an intellectual difficulty with the production of refrigeration: We could not learn it from nature.

The problem: One has to add energy to remove energy.


KK

warm

kalt

P?

P?

Q 0

.

warm

kalt

P

Q ab=Q O+P

Q 0

.

. .

Abb. 1.2.3 Zuführung der Antriebsleistung? Abb. 1.2.4 Kältemaschine

cold cold

Where should the outside power be applied

Solution: One needs an additional sytem: The

refrigerator


KKRefrigeration cyle

• Refrigerant

• Method to increase pressure

• Method to reduce entropy

• Method to reduce the temperature

• Method to transfer the refrigeration

• Recuperation

T-s Diagramm

Flow Diagram

Refrigeration

M in im umInput P ower

T a

T 0

E ntropy


KK

Tw

Tc

T

S

T

S

Tw

Tc

isentropic adiabatic

Cooling power

Widen the low-temperature end of the cycle as shown in the T-S diagram

Work Work

Ideal Real

S1 S2

AB

C D

AB

C D


KKCompressor and Aftercooler

• Purpose: Increase the pressure and reduce entropy

• Types of compressors

• Volumetric compressors: piston, screw

• Turbocompressors


KKPiston compressor

Oilfree labyrinth piston compressors. Preferred by CERN until about 1980.


KKScrew Compressor

Oil flooded screw compressor preferred at CERN since about 1985.


KKScrew compressor principle


KK


KKScrew Compressor Installation


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A B C D

Fig. 2 Low Temperature Options


KK


KK

10

100

1000

10000

100000

1,5 2 2,5 3 3,5 4 4,5

Refrigeration Temperature (K)

Re

frig

era

tio

n R

ate

(W

)

B

AE

CD

RIA

LHC

CEBAF

Tore Supra

ELBE

HERA

Tevatron

A Cold Ejector

B Cold Piston Compressor C Cold Turbocompressor, One Stage D Cold Turbocompressor Multi Stage

E Warm Vacuum Pump

Fig. 3 Cold Compressor diagram [3]


KK


KK

The four-stage LHC cold compressors1st stage

Cold Compressor Cartridges of 2.4 kW @ 1.8 K Refrigeration Units

IHI-Linde

Cold compressor impeller


KKIsentropic Efficiency of Cold

Compressors

0

10

20

30

40

50

60

70

80

1985 1993 2000Year of construction

Ise

ntr

op

ic e

ffici

en

cy [%

]

Tore Supra

CEBAF

LHC

12

12'is HH

HHη

Tem

pera

ture

(T

)

Entropy (s)

P1

P2

1

2

2'


KKFlow Compliance of “Mixed” Compression

N2

N3

Stall line

Choke line

Volumetric

P inter

Flow

P out (fixed)

P inter

P in (fixed)

Hydrodynamic

Volumetric

For fixed overall inlet & outlet conditions, coupling of the two machinesvia P inter maintains the operating point in the allowed range

N1

Flow (variable)


KKHow to evaluate efficiency and to identify

losses• When discussing expanders, we shortly

talked about reversibility• In power engineering there is always a best

method to do something, i. e. no unnecessary losses = reversibility

• Losses can be idebtified by the deviation from reversibility

• Comparison is the input power• We have to give refrigeration a value in the

scale of the input power• Carnot ratio


KKThe definition of exergy

• Minimum amount of work to produce refrigeration

• Exergy= Mimimum Power= Q*(Ta-T0)/T0

• Minimum amount of power to change the state of a fluid from an initial state 1 to a final state 2:

• e2-e1 = h2-h1 + Ta*(s2-s1)


KKCycle for liquefaction of

hydrogenThe Exergy Mountains

Prometheus(prehistoric)

Min

imu

m P

ow

er

to o

bta

in

Heati

ng

or

Cool in

g (

W/W

)


KK

Specific exergy of cold copper and helium

0

1000

2000

3000

4000

5000

6000

7000

8000

1 10 100 1000

Temperature

Sp

ecif

ic E

xerg

y (k

J/kg

) Copper (100*)

20 bar

2.2 bar

1 bar


KK

Stored exergy in the cooled-down LHC

Mass (tons)

Specific Exergy (MJ/kg)

Stored Exergy (GJ)

Helium 96 6.8 660 Metal 36.000 0.065 2.340 Total 3.000 Magnetic energy

10


KK

• Helium is recovered from natural gas


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Annual Helium Recovery and Sales (USA)

0

20

40

60

80

100

120

140

1960 1970 1980 1990 2000

Year

Vo

lum

e o

f H

eli

um

(M

ill

Nm

3 /ye

ar)

Sold

Recovered

Difference: Added or removed from reserve


KK

1999 Helium World Production (Estimated by U.S. Geological Survey)

Produced 106

Nm3/year

Liquefied 106 Nm3/year

Shipments per year

Shipments per week

United States 118,0 69,0 (export 29,3)

2450 49

Algeria 16,0 16,0 550 11 Russia 4,2 4,2 150 3 Poland 1,4 1,4 50 1 Total 139,6 90,6 3200 64 (15.000 l/h)


KK

00 1910 20 30 40 50 60 70 80 1990

LIQ

UE

FA

CT

ION

RA

TE

YE A R

0,1

1

10

100

1000

10000

0,4

4

40

400

4000

40000

RE

FR

IGE

RA

TIO

N R

AT

E

Wl/h

Development of the size of helium refrige-rators and liquefiers in the last century.


KKC.O.P. of Large Cryogenic Helium Refrigerators


KK

Joule-Thomson Wet ExpanderCollins (ca. 1965)

JT - TurbineFNAL 1975

Double JT - TurbineDESY HERA 1985

Triple JT -TurbineCERN LEP 1990

18 23 23 28 30Efficiency (%)

COP (W el /W refr ) 224240290290370

Fig. 4 Development of the Joule-Thomson Stage of Large Helium Refrigerators


KK

HX 1

HX 3

HX 4

HX 5

HX 6

HX 7

HX 10

HX 9

HX 11

HX 8

HX 2

5 - 8 KShield

40 - 80 KShield

2 K Load

T 1

T 2/3

T 4/5

T 6T 7

T 8

T 9

CC 2

CC 1

CC 3


KKTable 1 Cryogenic Accelerator and Fusion Projects

Project Location Capacity

(kW at 4.4 K) No. Refr

Refr. below 4.4 K Status

Accelerators Tevatron Fermilab 30 2+12 1.2 kW at 3.6 K operation RHIC Brookhaven 25 operation HERA DESY 30 3 4 kW at 3.7 K operation CEBAF TJNAF 12 5 kW at 2.0 K operation LEP CERN 72 4 stopped S-DALINAC Darmstadt 0.4 0.1 kW at 2.0 K operation ELBE Rossendorf 0.6 0.2 kW at 1.8 K operation LHC CERN 144 8 2.4 kW at 1.8 K construction Oak Ridge 12 5 kW at 2.0 K construction TESLA DESY 140 7 5 kW at 2.0 K adv. planning RIA [1] Argonne 30 8.6 kW at 2.0 K early planning SIS 100+200 GSI Darmstadt 20 ? early planning SASE-FEL BESSY 12 3.6 kW at 1.8 K early planning

Fusion MFTF Livermore 12 2 stopped JET Culham 1.5 2 0.6 kW at 3.8 K operation Tore Supra Cadarache 2 0.3 kW at 1.75 K operation TOSKA Karlsruhe 3 2 kW at 3.7 K operation LHD Toki 8 operation Wendelstein Greifswald 4 3 kW at 3.5 K construction SST-1 India 1 construction KSTAR Korea 10 construction ITER ? 120 planning


KKHistory of gas liquefaction


KK

History of use of liquid hydrogen

Hydrogen Bomb

HeavyWater

Commercial Supply

Rockets

Cold Neutron SourceBubble Chambers


KK


KK

Liquid Hydrogen

FuelledRocket


KK

BEBC (Big European Bubble Chamber at CERN)


KKLiquid Hydrogen Fuelled Car


KK


KKLiquid hydrogen tank in car


KKHydrogen

0

2

4

6

8

10

12

14

0 50 100 150 200 250 300

Temperature (K)

Sp

ecif

ic E

xerg

y (M

J/kg

)

0.1 MPa

2

10 MPa

4

6

e - H2

20,4


KKFuture Large Scale Hydrogen Liquefier

Feed

Product

Helium -Neon-Cycle

Propane

Hydrogen Com pressors

ColdH 2 Com pressor

M ain Com pressorBrake Com pressors

of T urb ines

HydrogenExpander

Expected Efficiency:60 % of Carnot7 kWh/kg LH2

Cryogenic Engineering, CERN, March 2004 Cryogenic Engineering CERN, March 8 - 12, 2004 Temperature...

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