Cryo Manual

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CRYOGENIC ENGINEERING LABORATORY

LABO ATO Y MANUAL

LIST OF EXPERIMENTS

1. Calibration of a cryogenic temperature measuring device2. Temperature measurements in cryogen and also in low

temperature set up.3. Strain measurements in aluminium sheet immersed inside liquid

nitrogen dewar.4. Strain measurements in cryogenically treated aluminium sheet

specimen.5. lectrical conductivity of titanium alloy and !etwic" niobium wires.

#. $emonstration of diamagnetic nature of %&C' superconductor

pellets.7. $emonstration of strength and hardness improvement in cryogenic

treatment.8. (easurement of electrical conductivity of cryogenically treated

copper.

9. ffect of cryogenic treatment in natural rubber )that is to chec" its

metallic behavior*.

LIST OF EQUIPMENTS

S.+

o

EQUIPMENT QUANTITY EXPERIMENT NO

, Strain gauge )Cryo* , 3-4


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2 Strain indicator , 3-4

3 Thermocouple )Cryo* 2 ,- 2

4 Temperature ndicator , ,- 2

5 $ewar )Cryo* , ,/0

# 1iquid +itrogen , ,/0

Superconductor 3 5- #

(ultimeter , 5-

0 ardness tester ,

, 6luminium Sheet , 3-4

,, Copper 7ire , ,2 Tool Steel 8iece ,

,3 $ie Steel 8iece ,

,4 8ermanent (agnet , #

,5 9ubber , 0

Calibrati! " a Cr#$%!i& T%''(%rat)r% M%a*)ri!$ +%,i&%

-T%r'&)(l%/

:. +o. ,

$ate ;

Ai'

To calibrate the thermocouple to measure cryogenic temperature

A((arat)*

,. Thermocouple2. Temperature indicator

2


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3. Cryogenic $ewar4. 1iquid +itrogen5. Copper wires#. Stainless steel wires

Pri!&i(l%

6 small voltage appears between the ends of a wire that is in a

temperature gradient. This voltage can be measured by connecting one

end- let us say the hot end of the wire- to another wire of a different

material that has a different voltage difference over the same

temperature range. 6 voltage will now appear between the cold ends of

the two wires )


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Thermocouple is calibrated to read liquid nitrogen temperature.

4


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T%'(%rat)r% M%a*)r%'%!t* i! Cr#$%! a!0 Al* L T%'(%rat)r%

S%t U(

:. +o. 2

$ate ;

Ai'

To calibrate the thermocouple to measure cryogenic temperature

A((arat)*

,. Themocouple

2. Temperature indicator3. Cryogenic $ewar4. 1iquid +itrogen5. ce#. Cryohydrate. Copper wires. Stainless steel wires

Pri!&i(l%

6 small voltage appears between the ends of a wire that is in a

temperature gradient. This voltage can be measured by connecting one

end- let us say the hot end of the wire- to another wire of a different

material that has a different voltage difference over the same

temperature range. 6 voltage will now appear between the cold ends of

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the two wires )


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Strai! '%a*)r%'%!t* i! al)'i!i)' *%%t i''%r*%0 i!*i0% li2)i0

!itr$%! 0%ar.

:. +o. 3

$ate ;

Ai'

To measure of strain in a aluminium sheet specimen at /,0#EC.

A((arat)*

,. Cryogenic $ewar2. 1iquid nitrogen3. Cryogenic strain gauge4. Strain indicator 5. 6luminium Sheet

Pri!&i(l%

n connection with the theoretical evaluation of an aluminum tan"

for liquid nitrogen storage- it was necessary to e:perimentally confirm

the e:pected low thermal stress level. So- aluminium sheet specimens

used ma"e liquid nitrogen storage tan" are immersed in liquid nitrogen

and strain is measured using strain gage/strain indicator set up )


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Pr&%0)r%

6luminium sheet specimen is bonded with strain gauge. The

specimen is tied in stainless steel wires and immersed in liquid nitrogen

for 5 mimutes. The readings shown by strain indicators are noted and

tabulated )Table ,*. This procedure is repeated for two more times and

average strain is calculated.

R%*)lt

Strain in a given aluminium specimen at liquid

nitrogen temperature in Bm>m

=

10


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Strai! '%a*)r%'%!t* i! &r#$%!i&all# tr%at%0 al)'i!i)' *%%t

*(%&i'%!

:. +o. 4

$ate ;

Ai'

To measure of strain in a aluminium sheet specimen at /,0#EC.

A((arat)*

,. Cryogenic $ewar

2. 1iquid nitrogen3. Cryogenic strain gauge4. Strain indicator 5. 8ulley with weights#. 6luminium Sheet

Pri!&i(l%

Cryogenically treated metallic specimens become strong and less

ductile. f we measure strain for a fi:ed tensile load- strain shown by

cryogenically treated specimen is less than that of untreated specimen

)


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6luminium sheet specimen is bonded with strain gauge. Strain

indicator is switched on. 6 tensile load of ,g is applied and strainreading is recorded )Table ,*. The same procedure is repeated by

increasing the load to 2g- 3g- 4g @ 5g and the respective strain

readings are recorded. +ow- the specimen is removed from the stand

and immersed in cryogen container for ,minutes. The strain

measurement procedure is repeated as done for untreated specimen for

various loads ),/5g*. The readings are recoreded )Table ,*.

R%*)lt

Strain was determined for various loadings.

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m*

Gntread Cryo/treated

,g

2g

3g

4g

5g

El%&tri&al R%*i*ti,it# " Al)'i!i)' All# a!0 G%ti&3 Nibi)'

:.+o.5

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$ate ;

AIM

9esistance of the superconducting material drops to Hero below a

certain temperature )Tc*.

A((arat)*

,. 6luminium alloy wire2. !etwic" niobium wire3. multimeter 4. $ewar 5. 1iquid nitrogen

Pri!&i(l%

+ormal conductors of electricity carry current by individual

electrons- which are sub=ect to inefficient- energy/absorbing interactions.

Superconductors- however- carry current in pairs of electrons called

Cooper pairs- ma"ing them near/perfect conductors. Superconductingmaterials can only form these Cooper pairs below a certain temperature-

the critical temperature- or Tc. So- superconductors show very low

resistance below Tc or Hero resistivity.

Pr&%0)r%

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1iquid nitrogen dewar is opened and given Superconductor

6luminium 7ire is immerse in liquid nitrogen for , minutes. +ow-

multimeter probes are connected to superconductor and resistance

shown is recorded )Table ,*. The e:periment is repeated with !etwic"

niobium wire and resistivity is recorded in Table , again.

R%*)lt

9esistance drops to Hero at critical temperature.

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+%'!*trati! " +ia'a$!%ti& Pr(%rt# " YBCO S)(%r&!0)&tr

:. +o. #

$ate ;

Ai'

To demonstrate the diamagnetic nature of superconductor.

A((arat)*

,. %&C' Superconductor2. Conductivity bridge3. Cryogenic $ewar4. 1iquid +itrogen

5. 8ermanent magnet#. !lass bea"er. Copper wires

Pri!&i(l%

The (eissner effect is an e:pulsion of a magnetic field from a

superconductorduring its transition to the superconducting state- cooled

in liquid nitrogen )


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Pr&%0)r%

%&C' disc is placed on Styrofoam tray )tea cup*. 1liquid nitrogen

is poured over the disc until it is completely immersed. 6fter the liquid

nitrogen stops boiling- a small rare earth magnet is dropped onto the

superconductor. The dense magnet is floating > levitating over

superconductor.

R%*)lt

$iamagnetic nature of superconductor is thus demonstrated.

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4ar0!%** a!0 Str%!$t I'(r,%'%!t i! Cr#$%!i& Tr%at'%!t

:.+o.

$ate ;

AIM

Cryogenic treatment to improve hardness and strength.

A((arat)*

,. Tool steel

2. $ie steel

3. multimeter

4. $ewar

5. 1iquid nitrogen

#. ardness tester

Pri!&i(l%

Tool and die steel becomes strong and hard when immersed in

liquid nitrogen for ,/2 hour. t is called Cryogenic Treatment. t is due to

increase the amount of martensite in the steelKs crystal structure-

21
http://en.wikipedia.org/wiki/Martensitehttp://en.wikipedia.org/wiki/Martensite


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increasing its strength and hardness- sometimes at the cost of

toughness)


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El%&tri&al R%*i*ti,it# " Cr#$%!i&all# Tr%at%0 C((%r 5ir%

:.+o.

$ate ;

AIM

Cryogenic treatment to improve electrical conductivity

A((arat)*

,. Copper wire2. multimeter 3. $ewar 4. 1iquid nitrogen

Pri!&i(l%

Cryogenic treatment is treatment of materials at e:tremely low

temperature )in liquid nitrogen*. Copper behaves even stranger by

increasing its conductivitydue to cryogenic treatment.

Pr&%0)r%

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!iven copper wire of "nown conductivity is hanged inside liquid

nitrogen for ,>2 hour. 6fter soa"ing the copper specimens are removed

from liquid nitrogen and are bought to room temperature. +ow-

conductivity is measured for cryogenically treated copper wires

specimens. The readings are tabulated )Table ,*

R%*)lt

Conductivity of copper after cryogenic treatment D

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Table , ; Conductivity measurement

Conductivity before $CT Conductivity after $CT

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El%&tri&al R%*i*ti,it# " Cr#$%!i&all# Tr%at%0 C((%r 5ir%

:.+o.0

$ate ;

AIM

Cryogenic treatment to change elasticity of rubber.

A((arat)*

,. 9ubber band2. multimeter

3. $ewar 4. 1iquid nitrogen

Pri!&i(l%

Cryogenic treatment is treatment of materials at e:tremely low

temperature )in liquid nitrogen*. 8lastics behave li"e glass at these

temperatures and rubber is e:tremely stiff that it could be mista"en for

metal. This treatment involves soa"ing specimen at this temperature for

a prescribed duration and bringing bac" to room temperature. The rate

of cooling and rate of heating play a very vital role in the ultimate

performance.

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Pr&%0)r%

!iven specimens made up of rubber are tied in stainless steel

wires and hanged inside liquid nitrogen for ,>2 hour. 6fter soa"ing the

rubber band specimens are removed from liquid nitrogen and are bought

to room temperature. +ow- elastic property of rubber is chec"ed for

cryogenically treated conditions. &rittle nature and metallic sound of

rubber are noted.

R%*)lt

&rittle nature and metallic sound in rubber are verified.

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Cryo Manual