KSR COLLEGE OF ENGINEERING(AUTONOMOUS)

MECHANICAL ENGINEERING

CRYOGENICS

PRESENT BY , K.DAVID JENNIS

INTRODUCTIONTHE MAIN POINTS TO BE DISCUSSE ARE:WHAT IS CRYOGENIC TECHWHY USES OF DEWAR FLASK IN

CYOGENICAPPLICATIONAERO SPACE IN CRYOGENICHISTORY OF CRYOGENIC ROCKET ENGINECRYOGENIC GRINDINGMERITS & DEMERITS OF CRYOGENICS

CRYOGENIC TECHNOLOGYThe 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.

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.

DEWAR FLASK

Liquid NitrogenNitrogen 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.

Application of cryogenicsAerospace – Cryogenic Rocket Engine

Manufacturing field

Medical field

Electronics field

Fuels research

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).

Cryogenics in India

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

PROCESS FLOW

Some of liquid nitrogen is utillised in cooling engine.

Pressure of liquid nitrogen is increased from 0.7MPa to 2.9MPa using turbo pumps.

ADVANTAGES: High energy per unit mass.

Economical.

DISADVANTAGE:

Handling and storage of cryogenic gases can be dangerous.

Explosion.

MANUFACTURING FIELD – CRYOGENIC GRINDING

PROBLEMS FACED IN COVENTIONAL GRINDING PROCESS:High heat generation.Less tool life.Loss of enteric oil in spice grinding.Oxidation.

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.

Schematic representation of Cryo Grinder

Merits and De- merits:Merits :

Lower grinding cost.Prevent oxidation.Finer particle size.No heat generation.

De merits:High operation cost.High power consumption.

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.

conclusionCryogenic 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.

Thank you.......