This document discusses cryogenic technology and applications of cryogenic fluids. It introduces cryogenics as the science of low temperatures below 123K and lists some common cryogenic fluids like hydrogen, helium, oxygen and nitrogen. It then describes the liquefaction processes for gases using simple systems like Linde-Hampson and more advanced ones like Claude and Collins systems which use expansion engines to further lower temperatures. Finally, it outlines several applications of cryogenics in areas like superconductivity, medicine, space and cryonics.

1. INDEX
 INTRODUCTON
 CRYOGENIC FLUIDS
 LIQUIFACTION OF GASES
 APPLICATION
 REFFERENCES

2. Cryogenic Technology:-
INTRODUCTION :-
Cryogenic is defined as science and technology of temperature bellow 123 k
The reason for temperature limit of 123k that it includes the normal boiling
points of the main atmospheric gases as well as methane.
Cryogenic deals with low temperatures from about 100k to absolute 0.

3. Cryogenic fluids –
The permanent gases such as oxygen, hydrogen, nitrogen, helium refer to
earlier change from gas to liquid at atmospheric pressure at normal
boiling point such liquids are known as cryogenic fluids or cryogens.

4. HYDROGEN :-
Hydrogen and helium are special cryogens
Hydrogen has its normal boiling point at 20.27k and it has a
pressure 1 atm. Also critical temperature and pressure are 33.19k
and 13.15 atm. Respectively
Hydrogen has 3 isotopes viz. hydrogen deuterium and tritium
Hydrogen exist in two molecular forms ortho and para
It has 2 protons and 2 electrons

5.  2 Protons posses a spin which gives angular momentum
 If the nuclear spin are in same direction for both the proton it is ortho
hydrogen and if it is in opposite direction for both the proton then it is para
hydrogen


6. Helium
 Helium is a inert gas and exist in mono atomic state
 It has got a boiling point of 4.25k
 Critical temperature and critical pressure for helium gas are 5.25k and
2.27bars resp.
 Helium exist in two isotopes helium 4 and 3 as liquid helium is further
cool bellow particular temperature 2.17k a new liquid phase Lhe-II
emerges out.

7.  The 2 liquids Lhe-I and Lhe-II are obtained.
 They are differentiate on the basis of viscosity
 Lhe-II exhibits property like 0 viscosity and large thermal
conductivity it also has a some effects such as 1)Thermo mechanical
effect 2) Mechano caloric effect 3) fountain effect 4)Rollin effect

8. Oxygen :-
 The air contained 20% oxygen
 It has boiling temperature at one atmospheric pressure is 90.2k
 Its critical pressure is 5.08 atm.
 Oxygen is slightly magnetic and exist in 3 stable isotopes O16, O17,O18
 Oxygen is magnetic and this property is utilizes to separate something
or to remove the magnetic materials from some area.
 Because of the unique properties of oxygen there is no substituted for
oxygen in any of its uses.

9. Liquid Nitrogen
 The nitrogen in air is 80%
 Its boiling temperature at atmospheric pressure is 77.4k
 It has a critical temperature and critical pressure are 126k and
33.9atm resp.
 It exist in 2 stable isotopes N14 and N15
 Air as we assume to be composed of nitrogen and oxygen by
fractional distillation of air it will be separated

10. Liquefaction of gases:-
 SIMPLE LINDE - HAMPSON SYSTEM :-
 Linde hampson cycle consist of compressor , heat exchanger and a J-T
expansion device
 The heat exchanger is use to conserved the cold that is produce at the
end the cold gas which goes back to compressor precools the
incoming hot gas so , whatever cold is produce is conserved in this
cycle

11.  DIAGRAME

12.  J-T expansion valve is used for reducing temperature with the J-T
expansion process
 It is an isenthalpic process means has constant enthalpy and initial
temperature of the gas should be less than inversion temperature to
have a cooling effect.

13. Claude-System:-

14. Claude – System :-
 In order to achieved a better performance and to approach ideality
the expansion proses should be reversible process
 For any gas , isentropic expansion results in lower temperature
respective of its inversion temperature
 The CLAUDE system consist of a compressor three 2 fluid heat
exchangers, a J-T expansion device and a make up gas connection
 The system also has an expansion engine operating across the 2nd
heat exchanger
 In this system the energy contained in the gas is removed by
allowing it to do some work in an expansion device

15.  This liquefaction proses will be explained by T-S diagram

16. Collins System :-
 Collins system is consider as one of the biggest milestone in
cryogenic engineering
 This system is an extension to Claude system
 The system has a compressor , a J-T expansion device ,a make up
gas connection five 2 fluid heat exchanger and two turbo expander
 expansion engines are used to removed the heat from the gas and
their by to reach lower and lower temperature

17. Application :-
Superconductivity
 The NMR (nuclear magnetic resonances )is used by pharmaceutical
industries to study the molecular structure
 The MRI ( magnetic resonances imagine)machines are used for body
scanning
 In maglev locomotion and SC transformer and generator

18. SPACE :-
 Rocket propulsion
 Cooling of infra red sensor
 Space simulation

19. MEDICINES :-
 Cryosurgery
 Cell preservation
 Food preservation

20. CRYONICS :-
 Cryonics is the practice of preserving human bodies in extremely cool
temperature with the hope of reviving them some time in the future.

21. References :-