three stage pulse tube cryocoolers

Three stage pulse tube cryocooler

Guided by:

Prof. S. M. Mehta

Prepared by:Vivek P. Sarvaiya

cryocoolers• What is cryocoolers?

• Cryocoolers are small refrigerators that can reach cryogenic temperatures and provide refrigeration in the temperature below 120 K.

• Why cryocoolers are required?

• long lifetime

• reliable and maintenance free operation

• minimum vibration and noise

• Compactness

• Lightweight

• adequate refrigeration at specified temperature with low power input

Applications

• Liquefaction of gases such as nitrogen, oxygen, hydrogen, helium, natural gas

• Cooling of super-conducting magnets

• Cooling of infra-red sensors for missile guidance

• Cryo vacuum pumps

• SQUID magnetometers

• Gamma ray sensors for monitoring nuclear activity

• Cooling of high temperature superconductors and semiconductors

Classification•Recuperative cryocoolers

• Joule-Thomson

• Bryton

• Claude

•Regenerative cryocoolers

• Stirling

• Pulse tube

• Gifford-McMahon

Pulse tube Cryocoolers

• W. E. Gifford and R. C. Longsworth, in 1960's, invented the so-called Basic Pulse Tube.

• The modern PTR was invented by Mikulin by introducing orifice in Basic pulse tube in 1984. He reached a temperature of 105 K.

Progress of pulse tube

Single-stage Stirling-PTR

AC

Regenerator

Cold Heat Exchanger

Pulse Tube

Hot Heat Exchanger

Orifice

ReservoirCompressor

• Regenerator: A matrix as a porous media having high heat capacity and low conductivity to exchange the heat with the gas (heart of the system).

• Hot heat exchangers: Release the heat created in the compression cycle to the environment.

• Cold heat exchangers: Absorbs the heat of the environment because of cooling down in the expansion cycle.

• After cooler (AC): Remove the heat of the compression in the compressor.

• Buffer: A reservoir having much more volume in compare with the rest of the system.

• Orifice: An inlet for the flow resistance.

• Compressor: Creating a harmonic oscillation for the gas inside the system.

AC

Regenerator

Cold Heat Exchanger

Pulse Tube

Hot Heat Exchanger

Orifice

ReservoirCompressor

Pulse tube coolers(WHY??)

• Reliable and Maintenance free operation

• No rubbing seals and rubbing forces due to replacement of displacer.

• Least Vibration at the cold tip due Elimination of cold moving parts.

How to achieve lower and lower temperature????

RESEARCHER

UNIT TYPE Pressure (bar)

Frequency (Hz)

Lowest temperature

Power Input

1st stage

2nd stage

Yang andThummes

‘U’ typeGas-Coupled

20.6 35 72 K 20.02 K 200 W

Radebaughet al

‘U’ typeThermally-Coupled

24.1 32.3 60 K 20 K 600 W

Chen et al ‘U’ typeThermally-Coupled

12 32 93.3 K 14.2 K 400 W

Three-Stage Stirling -PTR Reservoir 1 Reservoir 2 Reservoir 3

Orifice 1

Pulse-Tube 1

Reg. 1

Reg. 2

Reg. 3

Aftercooler

Compressor

Orifice 3

Pulse-Tube 3

Orifice 2

Pulse-Tube 2

Stage 1

30-100 K

15 k

4 k

Three stage pulse tube cryocooler

Operating condition of three stage pulse tube refrigerator

Y. Matsubara and J.L. Gao , cryogenics 34

Three stage pulse tube cryocooler1st stage: 37 W @ 45 K

2nd stage:15W @ 15 K

3rd stage:0.3 W @ 3.96 K

C.Wang, Cryocooler 14

Three stage pulse tube cryocoolerParameter 1st stage 2nd stage 3rd stage

Frequency (Hz) 40 30 30

Mean Pressure

(MPa)

2.0 1.0 1.0

PV Input Power

(W)

250 170 60

Bottom

Temperature (K)

37 11 4.9

Cooling power 15W@80K 1.4W@20K 60mW@6

K

Relative Carnot 16.5% 11.5% 4.9%

Required

Precooling

None 8W@90K 4.5W@90

K

1.2W@20

K

Q. Cao et al, Cryocoolers 16

Application of pulse tube cryocooler

• Military – Night vision Infrared Camera

• Space and Satellite – Infrared detector cooling

• Cryopumps

• Gas Cooling and Gas Liquefaction

• MRI and NMR SC Magnet cooling

• SC Transformer Motor and Generator

conclusion

• Staging in pulse-tube reduces the cooling power in subsequent stages.

• Staging in pulse tube cryocoolers decreases the temperature as stages increases

• Cooling power keep on reducing as stages keep on increasing.

Thank you

• Presented by

• Vivek Sarvaiya