Cryogenics is the study of very low temperatures, including temperatures below -150°C that can be attained using cryogenic liquids like liquid nitrogen and liquid helium stored in Dewar flasks. Some key applications of cryogenics discussed include cryogenic rocket engines, which provide high energy per unit mass and were pioneered by the US and India. Cryogenic grinding is also discussed as an application, which avoids problems with heat generation, tool wear, and oxidation seen in conventional grinding. Both advantages like lower grinding costs and finer particle sizes, and disadvantages like high operating costs are reviewed. Health hazards associated with cryogenic liquids like frostbite and cold embrittlement are also summarized.

1. CRYOGENICS
PRESENT BY ,
K.DAVID JENNIS

2. INTRODUCTION
THE MAIN POINTS TO BE DISCUSSE ARE:
 WHAT IS CRYOGENIC TECH
 WHY USES OF DEWAR FLASK IN CYOGENIC
 APPLICATION
 AERO SPACE IN CRYOGENIC
 HISTORY OF CRYOGENIC ROCKET ENGINE
 CRYOGENIC GRINDING
 MERITS & DEMERITS OF CRYOGENICS

3. CRYOGENIC TECHNOLOGY
 The word ‘cryogenics’ originates from Greek word
‘Cryo’ which means cold.
 Cryogenics is the study of very low temperature. The
temperature as low as-180 C are attained in cryogenic
system.
 Cryogenics is the study of low temperature and
behaviour of material under these low temperature.
 The cryogenic process also has a unique capability for
recycling difficult to separate composite material.

4.  The extremely low temperature are produced by using
substances called ‘cryogens’. Such as Liquid
Nitrogen(LN2) and Liquid Helium(LH2).
 Liquid Nitrogen are the most commonly used in
cryogenics.
 They have the boiling point of below -150 c.
 Cryogens are stored in vessels called as Dewar flask
which provides good insulation.

5. DEWAR FLASK

6. Liquid Nitrogen
 Nitrogen gas makes up the major portion of the
atmosphere (78.03%) by volume.
 Inert, colourless, odourless, non-corrosion, non-flammable
liquid.
 Extremely cold.
 Volume of expansion liquid to gas at 15 c 1atm. i.e 1 litre
of liquid nitrogen evaporated to form 682 litres of nitrogen
gas.

7. Application of cryogenics
Aerospace – Cryogenic Rocket Engine
Manufacturing field
Medical field
Electronics field
Fuels research

8. Aero space – Cryogenic Technology
in Rocket Propulsion
The united states was the first country to develop
cryogenic rocket engine.
with RL – 10 engine, registered its first successful
flight in 1963 and is still used on the Atlas V rocket.
On April 15, 2010, India launched communication
satellite GSAT-4 into orbit. The Geo –synchronous
Satellite Launch Vehicle (GSLV).

9. Cryogenics in India
C.E -7.5 is the India’s first cryogenic rocket

10. PROCESS FLOW

11.  Some of liquid nitrogen is utillised in cooling engine.
 Pressure of liquid nitrogen is increased from 0.7MPa
to 2.9MPa using turbo pumps.

12. ADVANTAGES:
High energy per unit mass.
Economical.
DISADVANTAGE:
Handling and storage of cryogenic gases can be
dangerous.
Explosion.

13. MANUFACTURING FIELD –
CRYOGENIC GRINDING
PROBLEMS FACED IN COVENTIONAL
GRINDING PROCESS:
High heat generation.
Less tool life.
Loss of enteric oil in spice grinding.
Oxidation.

14. Working of Cryo grinder:
 Material is to be cleaned manually fed
into the hopper.
 Liquid nitrogen from the storage
container is sprayer into screw
conveyer.(i,e) conveyer drive.
 The sensor monitor’s materials
temperature in the conveyer.
 When the mill is running the material
gets crushed between the studs &comes
out through an optional sleve as a
ground product.
 To the bottom of the mill a collecting
bin is housed.
 The vaparized nitrogen from the mill is
sucked by a centrifugal blower &
through the filter assembly. And the
cyclic process is continued.

15. Schematic representation of Cryo Grinder

16. Merits and De- merits:
 Merits :
 Lower grinding cost.
 Prevent oxidation.
 Finer particle size.
 No heat generation.
 De merits:
 High operation cost.
 High power consumption.

17. Health hazards of cryogenic liquids
 Skin and eye hazard: cryogens are extremely cold and can
cause instant,severe frostbite. The eye’s fluids will freeze
in cantact with a cryogens, causing permanent eye
damage.
 Cold Embrittlement: at cryogenic temperatures many
materials, such as rubber, plastic and carbon steel can
become so brittle that very little stress can break the
material.

18. conclusion
 Cryogenic grinding technology can efficiently grind
most tough material and can also facilitate cryogenic
recycling of tough composite materials.
 The cryogenic process also has a unique capability for
recycling difficult to separate composite materials.

19. Thank you.......