Brief about Cryogenics

1. Cryogenics

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Contents
 Introduction
 History of cryogenics
 Methods for producing cryogenic
Temperature
 Role of Cryogenics in Mechanical Engg
 Applications
 Advantages & Disadvantages
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 Cryogenics is the Production and behavior of
materials at very low temperatures.
 Lowest Temp. - 0 K
 Cryogenic Region - below 120 K
 The word cryogenics comes from the Greek
word cryos, meaning "cold," combined with a
shortened form of the English verb "to generate."
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Introduction

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 More specifically, a low-temperature environment
is termed a cryogenic environment when the
temperature range is below the point at which
permanent gases begin to liquefy.
 Permanent gases are elements that normally exist
in the gaseous state and were once believed
impossible to liquefy. Among others, they include
oxygen, nitrogen, hydrogen, and helium.
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 The mechanical and electrical properties of many
materials change very dramatically when cooled
to 100 K or lower.
 For example, rubber, most plastics, and some
metals become exceedingly brittle. Also many
metals and ceramics lose all resistance to the flow
of electricity, a phenomenon called
superconductivity.
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Cryogen °F °C K
Oxygen −297 −183 90
Nitrogen −320 −196 77
Hydrogen −423 −253 20
Helium −452 −269 4.2
Neon −411 −246 27
Argon −302 −186 87
Krypton −242 −153 120
Xenon −161 −107 166
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Cryogenics and Their Boiling Points

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History of
Cryogenics
 Cryogenics developed in the nineteenth
century as a result of efforts by scientists to
liquefy the permanent gases.
 By 1845, Faraday had managed to liquefy
most permanent gases then known to exist.
His procedure consisted of cooling the gas by
immersion in a bath of ether and dry ice and
then pressurizing the gas until it liquefied.

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 Finally, in 1877, Louis Cailletet (1832–1913)
in France and Raoul Pictet (1846–1929)
in Switzerland succeeded in producing the first
droplets of liquid air.
 Then, in 1883, the first measurable quantity of
liquid oxygen was produced by S. F. von
Wroblewski (1845–1888) at the University of
Krakow.
 James Dewar (1842–1923), a Scottish chemist,
succeeded in 1898. He found the boiling pointof
hydrogen to be a frosty 20 K.
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 Cryogenic conditions are produced by four basic
techniques:
 Heat conduction, Evaporative cooling, Cooling by
rapid expansion (the Joule-Thomson effect), and
Adiabatic demagnetization.
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Methods for
Producing
Cryogenic Temp

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 Heat conduction is a relatively simple concept to understand.
When two bodies are in contact, heat flows from the body with the higher temperature to the body
with a lower temperature.
Conduction can occur between any and all forms of matter, whether gas, liquid, or solid. It is essential
in the production of cryogenic temperatures and environments.
 Evaporative Cooling , In cryogenics a container of liquid is allowed to evaporate. Heat from within the
liquid is used to convert particles at the surface of the liquid to gas. The gas is then pumped away. More heat
from the liquid converts another surface layer of particles to the gaseous state, which is also pumped away.
The longer this process continues, the more heat is removed from the liquid and the lower its temperature
drops.
 Joule-Thomson effect, the gas is first pumped into a container under high pressure. The container is fitted
with a valve with a very small opening. When the valve is opened, the gas escapes from the container and
expands quickly. At the same time, its temperature drops. The first great success for the Joule-Thomson
effect in cryogenics was achieved by Kamerlingh Onnes in 1908 when he liquefied helium.
 Adiabatic demagnetization has been used to produce some of the coldest temperatures ever observed—
within a few thousandths of a degree kelvin of absolute zero. A related process involving the magnetization
and demagnetization of atomic nuclei is known as nuclear demagnetization. With nuclear demagnetization,
temperatures within a few millionths of a degree of absolute zero have been reached.
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 Cryogenic engineering is a sub stream
of mechanical engineering dealing
with cryogenics, and related very low temperature
processes such as air liquefaction, cryogenic
engines (for rocket propulsion), cryosurgery.
 Cryogenic treatment works on Reamers, Tool bits,
Tool punches, Carbide Drills, Carbide Cutters,
Milling Cutters, Files, Knives, Reciprocating
Blades, Dies and cutting tools.
 Stress relieved ferrous and non ferrous castings
and forgings for enhanced dimensional stability
and surface finish.
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Role of Cryogenics
in Mechanical
Engg

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 Sustainable machining methods (cleaner, safer,
environment friendly, more health acceptable, etc.)
to eliminate numerous costs associated with
conventional cutting fluid sand clean-up operations,
 Increase of material removal rate without increases
in worn tool and tool change over costs – increase
of productivity
 Surface roughness of machined work piece
improvement.
 Produced parts quality improvement by preventing
mechanical and chemical degradation of machined
surface.
Cryogenic
Machining

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 High Energy per unit mass
Propellants like oxygen and
hydrogen in liquid form give high amount of
energy per unit mass due to which the amount of
fuel to be carried aboard the rocket decrease.
 Economical
Use of oxygen and nitrogen as
fuels is very economical, liquid oxygen cost is less
than gasoline.
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Advantages

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 Handling and storage of cryogenic gases can be
dangerous
 Low temperature hazard and oxygen
enrichment/deficiency hazard (Asphyxiation)
 Explosion
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Limitations

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 CRYOGENIC ENGINES IN AEROSPACE
First operational Cryogenic Rocket
Engine is 1961 NASA designed RL-10 LOX
LH2 rocket engine
The second-stage Pratt & Whitney
RL10B-2 engine is based on the 30-year heritage of the
reliable RL10 engine
 Cryosurgery- Use of extreme cold produced by
liquid nitrogen (or argon gas) to destroy abnormal
tissue.
Used to treat external tumors, such as those
on the skin.
For internal tumors, liquid nitrogen is
circulated through a hollow instrument called a
Cryoprobe.
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Applications

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 Frozen Food:
Transportation of large masses of
frozen food. Food is freezed in war zones,
earthquake hit regions, etc. Cryogenic food freezing
is also helpful for large scale food processing
industries
 Bloodbanking
Certain rare blood groups are stored
at low temperatures, such as −165 °C
 Special effects
Liquid nitrogen and CO2 has been
built into nightclub effect systemsby Kryogenifex to
create a chilling effect and white fog that can be
illuminated with colored lights.
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Applications

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porous tungsten machining
This experimental study focuses on high
performance cryogenic machining of porous
tungsten, which is classified as difficult-to-machine
material, where the quality of machined surface
through porosity is one of the most important
objectives
Tungsten has high mechanical and physical
properties and has the highest melting point of all the
non-alloyed metals and the second highest of all the
elements after carbon .Tungsten is often brittle and
hard to work in its rawstate
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Case Study

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 Great scope for cryogenics in the near future.
Fields like medicine, space travel, deep sea fishing
etc besides the existing usages in industry,
scanning and imaging grinding of spices and so
on. Recently the old tyres were frozen in Liquid
Nitrogen and fronded to separate steel and rubber
for recycling.
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Future scope in
Cryogenic Tech.

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 Cryogenic fuels are fuels that require storage at
extremely low temperatures in order to maintain
them in a liquid state. These fuels are used in
machinery that operates in space (e.g. rocket ships
and satellites) because ordinary fuel cannot be
used there, due to absence of an environment that
supports combustion (on Earth, oxygen is
abundant in the atmosphere, whereas in human-
explorable space, oxygen is virtually non-existent)
and space is a vacuum. Cryogenic fuels most often
constitute liquefied gases such as liquid hydrogen.
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Cryogenic Fuels

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 Cryogenic fuels are environmentally cleaner than
gasoline or fossil fuels. Among other things,
the greenhouse gas rate could potentially be
reduced by 11–20% using LNG as opposed to
gasoline when transporting goods.
 Along with their eco-friendly nature, they have
the potential to significantly decrease
transportation costs of inland products because of
their abundance compared to that of fossil fuels.
Drawbacks
 Some cryogenic fuels, like LNG, are naturally
combustible. Ignition of fuel spills could result in
a large explosion. This is possible in the case of a
car crash with an LNG engine.
 Cryogenic storage tanks must be able to withstand
high pressure. High-pressure propellant
tanks require thicker walls and stronger alloys
which make the vehicle tanks heavier, thereby
reducing performance and practicality.
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Advantage&Draw
backs of Cryogenic
fuels

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