CRYOGENICS
#1

The science and technology of deep refrigeration processing occurring at temperatures lower than about 150 k. is the field of cryogenics. The name cryogenics is evolved from Greek word ?kryos? meaning icy cold. Phenomena that occurs at cryogenic temperatures include liquefaction and solidification of ambient gases; loss of ductility and embrittlement of some structural materials such as carbon steel; increase in thermal conductivity to a maximum value, followed by further decrease in temperature. Cryogenics is the low temperature (150 K) refrigeration. It explains the properties of cryogens used and their principles. Storage methods and handling techniques are covered. Cryogenics are applied in different fields of production, transportation, medicine, aerospace, physics research etc. Rocket propulsion is imparting force to a flying vehicle such as missile or spacecraft. Different types of rockets and their parts are explained. Cryogenics has future applications in many fields like superconductivity and propulsion fields. Cryogenics is being applied to variety of research areas; a few of which are: food processing and refrigeration, space craft life supporting system, space simulation, microbiology, medicine, surgery, electronics, data processing and metal working. Rocket propulsion is the process of imparting a force to flying vehicle such as a missile, by momentum of ejected matter. The matter, called propellant, is stored in the vehicle and ejected at high velocity. In chemical rocket, the propellants are chemical compounds that undergo a chemical combustion reaction releasing the energy for thermodynamically accelerating and ejecting the gaseous reaction products at high velocities. Chemical rocket propulsion is thus differential from other types of rocket propulsion which use nuclear, solar or electrical energy as their power source and which may use mechanism other than adiabatic expansion of a gas for achieving high ejection velocities.
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#2
i wanna details of this seminars
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#3
cryogenics is the study of the production of very low temperature (below -150 °C, -238 °F or 123 K) and the behavior of mLiquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached.

These liquids are held in either special containers known as Dewar flasks, which are generally about six feet tall (1.8 m) and three feet (91.5 cm) in diameter, or giant tanks in larger commercial operations. Dewar flasks are named after their inventor, James Dewar, the man who first liquefied hydrogen. Museums typically display smaller vacuum flasks fitted in a protective casing
aterials at those temperatures.


for making cryogenics temperature normally linde hampson system is using
see more

http://en.wikipediawiki/Cryogenics
http://sdl.usu.edu/products-http://www-b...genics.pdf
http://physics.princeton.edu/mumu/target...020905.doc
http://scribddoc/22057879/Cryogenics-and-heat-treatment
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#4
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1. INTRODUCTION
The science and technology of deep refrigeration processing occurring at temperature lower than about 150 k. is the field of cryogenics. The name cryogenics is evolved from Greek word ËœCryosâ„¢ meaning icy cold. Phenomena that occurs at cryogenic temperatures include liquefaction and solidification of ambient gases; loss of ductility and embrittlement of some structural materials such as carbon steel; increase in thermal conductivity to a maximum value, followed by further decrease in temperature. Cryogenics is the low temperature (150 K) refrigeration. It explains the properties of cryogens used and their principles. Storage methods and handling techniques are covered.
Cryogenics are applied in different fields of production, transportation, medicine, aerospace, physics research etc. Rocket propulsion is imparting force to a flying vehicle such as missile or spacecraft. Different types of rockets and their parts are explained. Cryogenics has future applications in many fields like superconductivity and propulsion fields. Cryogenics is being applied to variety of research areas; a few of which are: food processing and refrigeration, space craft life supporting system, space simulation, microbiology, medicine, surgery, electronics, data processing and metal working.
The origin of cryogenics as a scientific discipline coincided with the discovery by nineteenth-century scientists that the permanent gases can be liquefied at exceedingly low temperatures. Consequently, the term "cryogenic" applies to temperatures from approximately -100°C (-148°F) down to absolute zero (the coldest point a material could reach). In 1848, English physicist William Thomson (later known as Lord Kelvin; 1824“1907) pointed out the possibility of having a material in which particles had ceased all forms of motion.
The absence of all forms of motion would result in a complete absence of heat and temperature. Thomson defined that condition as absolute zero.
2. HISTROY
Cryogenics developed in the nineteenth century as a result of efforts by scientists to liquefy the permanent gases. One of the most successful of these scientists was English physicist Michael Faraday (1791“1867). 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.
Six gases, however, resisted every attempt at liquefaction and were known at the time as permanent gases. They were oxygen, hydrogen, nitrogen, carbon monoxide, methane, and nitric oxide. The noble gases”helium, neon, argon, krypton, and xenon”were yet to be discovered. Of the known permanent gases, oxygen and nitrogen (the primary constituents of air), received the most attention.
For many years investigators labored to liquefy air. 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. Oxygen was found to liquefy at 90 K, and nitrogen at 77 K.
Following the liquefaction of air, a race to liquefy hydrogen ensued. James Dewar (1842“1923), a Scottish chemist, succeeded in 1898. He found the boiling point of hydrogen to be a frosty 20 K. In the same year, Dewar succeeded in freezing hydrogen, thus reaching the lowest temperature achieved to that time, 14 K. Along the way, argon was discovered (1894) as an impurity in liquid nitrogen. Somewhat later, krypton and xenon were discovered (1898) during the fractional distillation of liquid argon. (Fractional distillation is accomplished by liquefying a mixture of gases, each of which has a different boiling point. When the mixture is evaporated, the gas with the highest boiling point evaporates first, followed by the gas with the second highest boiling point, and so on.)
Each of the newly discovered gases condensed at temperatures higher than the boiling point of hydrogen but lower than 173 K. The last element to be liquefied was helium gas. First discovered in 1868 in the spectrum of the Sun and later on Earth (1885), helium has the lowest boiling point of any known substance. In 1908, Dutch physicist Heike Kamerlingh Onnes (1853“1926) finally succeeded in liquefying helium at a temperature of 4.2 K.
2.1 Words to Know:
Absolute zero: The lowest temperature possible at which all molecular motion ceases. It is equal to -273°C (-459°F).
Kelvin temperature scale: A temperature scale based on absolute zero with a unit, called the Kelvin, having the same size as a Celsius degree.
Superconductivity: The ability of a material to conduct electricity without resistance. An electrical current in a superconductive ring will flow indefinitely if a low temperature (about -260°C) is maintained.
3. METHODS OF PRODUCING CRYOGENIC TEMPERATURES
Cryogenic conditions are produced by one of four basic techniques:
1. Heat conduction,
2. Evaporative cooling,
3. Cooling by rapid expansion (the Joule-Thomson effect), and
4. Adiabatic demagnetization.
The first two are well known in terms of everyday experience. The third is less well known but is commonly used in ordinary refrigeration and air conditioning units, as well as in cryogenic applications. The fourth process is used primarily in cryogenic applications and provides a means of approaching absolute zero.
3.1 HEAT CONDUCTION TECHNIQUE:
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. For example, samples may be cooled to cryogenic temperatures by immersing them directly in a cryogenic liquid or by placing them in an atmosphere cooled by cryogenic refrigeration. In either case, the sample cools by conduction (or transfer) of heat to its colder surroundings.
CRYOTUBES:
Cryotubes used to store strains of bacteria at low temperature. Bacteria are placed in little holes in the beads inside the tubes and then stored in liquid nitrogen.
3.2 EVOPARATIVE COOLING TECHNIQUE:
The second process for producing cryogenic conditions is evaporative cooling. Humans are familiar with this process because it is a mechanism by which our bodies lose heat. Atoms and molecules in the gaseous state are moving faster than atoms and molecules in the liquid state. Add heat energy to the particles in a liquid and they will become gaseous. Liquid perspiration on human skin behaves in this way. Perspiration absorbs body heat, becomes a gas, and evaporates from the skin. As a result of that heat loss, the body cools down.
Cryogens and Their Boiling Points
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. Once some given temperature is reached, pumping continues at a reduced level in order to maintain the lower temperature. This method can be used to reduce the temperature of any liquid. For example, it can be used to reduce the temperature of liquid nitrogen to its freezing point or to lower the temperature of liquid helium to approximately 1 K.
3.3 COOLING BY RAPID EXPANSION (JOULES THOMSON EFFECT):
A third process makes use of the Joule-Thomson effect, which was discovered by English physicist James Prescott Joule (1818“1889), and William Thomson, Lord Kelvin, in 1852. The Joule-Thomson effect depends on the relationship of volume (bulk or mass), pressure, and temperature in a gas. Change any one of these three variables, and at least one of the other two (or both) will also change. Joule and Thomson found, for example, that allowing a gas to expand very rapidly causes its temperature to drop dramatically. Reducing the pressure on a gas accomplishes the same effect.
To cool a gas using the 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.
The Joule-Thomson effect is an important part of our lives today, even though we may not be aware of it. Ordinary household refrigerators and air conditioners operate on this principle. First, a gas is pressurized and cooled to an intermediate temperature by contact with a colder gas or liquid. Then, the gas is expanded, and its temperature drops still further. The heat needed to keep this cycle operating comes from the inside of the refrigerator or the interior of a room, producing the desired cooling effect.
3.4 ADIABATIC DEMAGNETIZATION TECHNIQUE:
The fourth process for producing cryogenic temperatures uses a phenomenon known as adiabatic demagnetization. Adiabatic demagnetization makes use of special substances known as paramagnetic salts. A paramagnetic salt consists of a very large collection of particles that act like tiny (atom-sized) magnets. Normally these magnetic particles are spread out in all possible directions. As a result, the salt itself is not magnetic. That condition changes when the salt is placed between the poles of a magnet. The magnetic field of the magnet causes all the tiny magnetic particles in the salt to line up in the same direction. The salt becomes magnetic, too.
At this exact moment, however, suppose that the external magnet is taken away and the paramagnetic salt is placed within a liquid. Almost immediately, the tiny magnetic particles within the salt return to their random, every-which-way condition. To make this change, however, the particles require an input of energy. In this example, the energy is taken from the liquid into which the salt was placed. As the liquid gives up energy to the paramagnetic salt, its temperature drops.
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.
4. APPLICATIONS
4.1 INDUSTRIAL APPLICATIONS:
Cryogenic treatment works on Reamers (carbide or HSS), Tool Bits, Tool Punches (carbide or HSS), Carbide Drills, Carbide Cutters, Milling Cutters, Files, Shaping Equipment, Scissors, Razors, Clippers, Knives, Band Saw Blades, Saw Blades, Reciprocating Blades, Saber Saw, Steel Woodworking and Form Tooling, Cutting Tools and Dies. In all cases, this treatment will result a stronger and more wear resistant metal.
4.2 AUTOMOTIVE APPLICATIONS:
Imagine a racer and crew who would normally tear down their engine after every race or two, suddenly discovering a process that would allow them to safely go up to 30 races or more without a major rebuild. Cryogenic treatment of automotive parts can certainly help make this a reality.
Cryogenics works with almost all metal engine parts. Pistons, rings, rockers, push rods, connecting rods, valves, the crank and camshaft and even the block itself. Together, a treated engine can last substantially longer in terms of wear than any other process could achieve. Even parts like brake rotors, drums, and brake pads can benefit from cryogenic treatment. Really, almost any part that is normally subject to wear can benefit. Just imagine what cryogenic treatment would do for the parts in your family vehicle!
4.3 MEDICL APPPLICATIONS:
Cryogenics has also been used by the medical industry. Surgical tools used by doctors, surgeons, dentists, and other specialistâ„¢s can all benefit from the increased wear resistance of the treatment. Surgical tools, like many other industrial tools, are expensive to replace, so cryogenic treatment can really pay off.
In addition, many surgical implants are also treated. This helps prevent the part from wearing, it increases the tensile and bending strength of the part, as well as reducing the likelihood of micro fracturing. Cryogenics really is a healthy choice for the medical field.
4.4 SPACE APPLICATIONS:
Cryogenic liquids are also used in the space program. For example, cryogenic materials are used to propel rockets into space. A tank of liquid hydrogen provides the fuel to be burned and a second tank of liquid oxygen is provided for combustion. Another space application of cryogenics is the use of liquid helium to cool orbiting infrared telescopes. Infrared telescopes detect objects in space not from the light they give off but from the infrared radiation (heat) they emit. However, the operation of the telescope itself also gives off heat. What can be done to prevent the instrument from being blinded by its own heat to the infrared radiation from stars The answer is to cool parts of the telescope with liquid helium. At the temperature of liquid helium (1.8 K) the telescope can easily pick up infrared radiation of the stars, whose temperature is about 3 K.
5. ADVANTAGES AND DISADVANTAGES
ADVANTAGES:
Cryogenics can produce large quantities of high purity (parts per billion contaminations) nitrogen. Some processes like the humid-air expansion process have a yield of about 40%-60% per pass, which allows you produce large quantities of nitrogen efficiently. Other processes, like the waste expansion, have a yield of about 25-40% per pass.
Cryogenic processes do not have economics of scale, i.e., expansion or reduction of product quantity requirements generally does not necessitate new equipment.
DISADVANTAGES:
Cryogenic processes in general have very large capital cost, due mostly to the cost of compressors and turbines. The high pressure requirements and the recovery of refrigeration energy explain the need for this equipment. Cryogenic separation requires the use of not only the compressors and turbines, but also numerous heat exchangers, insulators, and a distillation column; all of which add to the high costs of the process.
6. CONCLUSION
In this seminar report titled CRYOGENICS having the methods to produce the cryogenics temperatures and many advantages which are used for industries, automotives, medical field, space crafts, etc...This seminar report has given me more experience and knowledge on the cold generation and helped me to understand what cryogenics is, how it is produced, where it has been used and what is the use of cryogenics.
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#5
INTRODUCTION:-

Cryogenics originated from two Greek words kyros which means cold or freezing and genes which means born or produced. Cryogenics is the study of very low temperatures or the production of the same. Liquefied gases like liquid nitrogen and liquid oxygen are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest temperatures to be reached. These gases can be stored on large tanks called Dewar tanks, named after James Dewar, who first liquefied hydrogen, or in giant tanks used for commercial applications.

The field of cryogenics advanced when during world war two, when metals were frozen to low temperatures showed more wear resistance. In 1966, a company was formed, called CyroTech, which experimented with the possibility of using cryogenic tempering instead of Heat Treating, for increasing the life of metal tools. The theory was based on the existing theory of heat treating, which was lowering the temperatures to room temperatures from high temperatures and supposing that further descent would allow more strength for further strength increase. Unfortunately for the newly-born industry the results were unstable as the components sometimes experienced thermal shock when cooled too fast. Luckily with the use of applied research and the with the arrival of the modern computer this field has improved significantly, creating more stable results.
Another use of cryogenics is cryogenic fuels. Cryogenic fuels, mainly oxygen and nitrogen have been used as rocket fuels. The Indian Space Research Organisation (ISRO) is set to flight-test the indigenously developed cryogenic engine by early 2006, after the engine passed a 1000 second endurance test in 2003. It will form the final stage of the GSLV for putting it into orbit 36,000 km from earth.
It is also used for making highly sensitive sensors for detecting even the weakest signals reaching us from the stars. Most of these sensors must be cooled well below the room temperature to have the necessary sensitivity, for example, infrared sensors, x-ray spectrometers etc. The High resolution Airborne Widebandwidth Camera, for SOFIA (Stratospheric Observatory For Field Astronomy) which is a Boeing 747 flying observatory, a project of the University Of Chicago, Goddard Space Flight Center and the Rochester Institute Of Technology, which when enters into operation will be the largest infra-red telescope available, is cooled by an adiabatic demagnetization refrigerator operating at a temperature of 0.2K.
Another branch of cryogenics is cryonics, a field devoted to freeze people, which is used to freeze those who die of diseases, that they hope will be curable by the time scientists know how to revive people.

CRYOGENIC ENGINES

The use of liquid fuel for rocket engines was considered as early as the beginning of this century. The Russian K.E.Ziolkowsky, the American H.Goddard and the German-Romanian H.Oberth worked independently on the problems of spaceflight and soon discovered that in order to succeed, rockets with high mass-flow were mandatory. Already then the combustion of liquid fuels seemed the most promising method of generating thrust.
However it was not later until these pioneers made their attempts, the first big liquid powered rocket the German A-4 became reality in the mid-forties. This rocket became successful as the V-2 weapon. Liquid oxygen was used as the oxidizer and ethyl alcohol as the fuel which gave the rocket more than 300KN of thrust. It`s range was 300km.
As the development of rocket engines continued, higher thrust levels were achieved when liquid oxygen and liquid hydrocarbon were used as fuel. This allowed the construction of the first intercontinental rocket with a range of more than 10,000km.
The fuel combination of liquid oxygen and RP-1 a kerosene-like hydrocarbon compound, was the basis for the American intercontinental rockets like Atlas and Titan-1 as well as the boosters for the Saturn family of the Apollo Moon Program. Combinations of oxygen or fluoride as oxidizer and hydrogen or methane as fuel make them attractive fuel mixtures for rockets. The real disadvantage is, their low density.
Under normal atmospheric conditions, at temperature 300k and pressure 1 bar, these substances are in gaseous state. One cannot remedy the low density by increasing the pressure because the required tank structures would end being too heavy. The answer is to liquefy the fuels by cooling them down. This is why the fuels are also called cryogenic fuels.
In the sixties, the steadily increasing payload weights and the corresponding demand for more thrust of the launcher lead to the use of liquid hydrogen for the Centaur upper stage. At the peak of this development was the US Space Shuttle Main Engine (SSME).
In principle, cryogenic rocket engines generate thrust like all other rocket engines-by accelerating an impulse carrier to high speeds. In conventional aircraft engines the surrounding air is the main impulse carrier and fuel is the energy carrier. This is why such an engine requires the atmosphere not only to burn the fuel but also to generate thrust. But in rocket engines the impulse and energy carriers are identical and are present as fuel in the launcher. The chemical energy stored in the fuel is converted into kinetic energy by burning it in the thrust chamber and subsequent expansion in the nozzle, in the process creating thrust.
Inorder to compare a variety of fuel combinations, a quantity known as specific impulse, which determines the thrust per kilogram of emitted fuel per second, is used. For example hydrazine has 230 seconds of specific impulse, for solid propellants it is around 290 seconds. The favourite fuel and oxidizer combination used during the boost phase are Liquid Hydrogen(LH2) and Liquid Oxygen(LOX) which provide a specific impulse of 445 seconds, almost double that of hydrazine. The fuel is environmentally friendly, non-corrosive and has the highest efficiency of all non-toxic combinations. To liquefy hydrogen has to be cooled to a temperature of minus 273C. It`s boiling point is 20K only just above absolute on the temperature scale. During this process, it`s density increases to above 70kg/m3. Liquefaction of oxygen takes place at a temperature of minus 183C, it`s then is 1,140kg/m3.
Thus fuelling the booster rockets is a complex and hazardous process, for as soon as oxygen comes in contact with hydrogen, they spontaneously combust in a powerful explosion. Over the years cryogenic engines have become the backbone for boosters, used for placing heavy payloads in space, such as those used for the main engine for the space shuttle.
The major components of a liquid fuel cryogenic engine are the thrust chamber, the fuel pumps with it`s valves and regulators and the tanks. The fuel and oxidizer pump system is the main component and can be divided into two principles. The most simple way is to increase the pressure of the tank with inertial gases to pressurize the tanks against the pressure in the combustion chamber. In this type of engine, the fuel and gas tanks are very heavy and are used in smaller rockets with shorter burning times.
The alternative is to use turbopumps. This can be differentiated into a bypass or a main flow configuration. In the bypass configuration, the flow is split, the main part is used via the combustion chamber to generate thrust, while a small amount of fuel is used to drive the pump through the turbine and is subsequently emitted. In the main flow design, the entire fuel is fed through the turbines, which drives the pumps, and then further to the combustion chamber.
The combustion chamber is a critical component of the engine because of the high output and accordingly high pressures. High pressures over 200 bar and temperatures of more than 3,000F create a great strain on the combustion chamber and call for effective cooling. Copper combustion chambers are used, in the outside of which cooling channels are milled that are galvanoplastically closed. The SSME creates a vacuum thrust of 2,090 KN and a specific impulse of 452s. The three engines, which are needed for the main stage of the SSME have a combined output of more than 37 million hp or 27,380 megawatts, which correspond to about 30 conventional nuclear power plants.
Over the years there has been talk about designing a cryogenic system that could be used for the heavier upper stages for space systems. This would require cryogenic engines with great thermal insulation to protect the hydrogen and oxygen from friction heating during the boost phase and from solar heating after reaching space. With the ongoing research, one can anticipate a bright future for cryogenics in the field of rocket propulsion in th future.
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#6
Definition
Cryogens are effective thermal storage media which, when used for automotive purposes, offer significant advantages over current and proposed electrochemical battery technologies, both in performance and economy. An automotive propulsion concept is presented which utilizes liquid nitrogen as the working fluid for an open Rankine cycle. The principle of operation is like that of a steam engine, except there is no combustion involved. Liquid nitrogen is pressurized and then vaporized in a heat exchanger by the ambient temperature of the surrounding air. The resulting high - pressure nitrogen gas is fed to the engine converting pressure into mechanical power. The only exhaust is nitrogen.

The usage of cryogenic fuels has significant advantage over other fuel. Also, factors such as production and storage of nitrogen and pollutants in the exhaust give advantage for the cryogenic fuels

INTRODUCTION

The importance of cars in the present world is increasing day by day. There are various factors that influence the choice of the car. These include performance, fuel, pollution etc. As the prices for fuels are increasing and the availability is decreasing we have to go for alternative choice.

Here an automotive propulsion concept is presented which utilizes liquid nitrogen as the working fluid for an open Rankine cycle. When the only heat input to the engine is supplied by ambient heat exchangers, an automobile can readily be propelled while satisfying stringent tailpipe emission standards. Nitrogen propulsive systems can provide automotive ranges of nearly 400 kilometers in the zero emission mode, with lower operating costs than those of the electric vehicles currently being considered for mass production. In geographical regions that allow ultra low emission vehicles, the range and performance of the liquid nitrogen automobile can be significantly extended by the addition of a small efficient burner. Some of the advantages of a transportation infrastructure based on liquid nitrogen are that recharging the energy storage system only requires minutes and there are minimal environmental hazards associated with the manufacture and utilization of the cryogenic "fuel". The basic idea of nitrogen propulsion system is to utilize the atmosphere as the heat source. This is in contrast to the typical heat engine where the atmosphere is used as the heat sink.

HISTORY

The LN2000 is an operating proof-of-concept test vehicle, a converted 1984 Grumman-Olson Kubvan mail delivery van. Applying LN2 as a portable thermal storage medium to propel both commuter and fleet vehicles appears to be an attractive means to meeting the ZEV regulations soon to be implemented. Pressurizing the working fluid while it is at cryogenic temperatures, heating it up with ambient air, and expanding it in reciprocating engines is a straightforward approach for powering pollution free vehicles. Ambient heat exchangers that will not suffer extreme icing will have to be developed to enable wide utility of this propulsion system.

Since the expansion engine operates at sub-ambient temperatures, the potential for attaining quasi-isothermal operation appears promising. The engine, a radial five-cylinder 15-hp air motor, drives the front wheels through a five-speed manual Volkswagen transmission. The liquid nitrogen is stored in a thermos-like stainless steel tank. At present the tank is pressurized with gaseous nitrogen to develop system pressure but a cryogenic liquid pump will be used for this purpose in the future. A preheater, called an economizer, uses leftover heat in the engine's exhaust to preheat the liquid nitrogen before it enters the heat exchanger. The specific energy densities of LN2 are 54 and 87 W-h/kg-LN2 for the adiabatic and isothermal expansion processes, respectively, and the corresponding amounts of cryogen to provide a 300 km driving range would be 450 kg and 280 kg. Many details of the application of LN2 thermal storage to ground transportation remain to be investigated; however, to date no fundamental technological hurdles have yet been discovered that might stand in the way of fully realizing the potential offered by this revolutionary propulsion concept




Cryogens are effective thermal storage media which, when used for automotive purposes, offer significant advantages over current and proposed electrochemical battery technologies, both in performance and economy. An automotive propulsion concept is presented which utilizes liquid nitrogen as the working fluid for an open Rankine cycle. The principle of operation is like that of a steam engine, except there is no combustion involved. Liquid nitrogen is pressurized and then vaporized in a heat exchanger by the ambient temperature of the surrounding air. The resulting high – pressure nitrogen gas is fed to the engine converting pressure into mechanical power. The only exhaust is nitrogen.
The usage of cryogenic fuels has significant advantage over other fuel. Also, factors such as production and storage of nitrogen and pollutants in the exhaust give advantage for the cryogenic fuels.
Posted by Praveen at 7:03 PM
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#7
PRESENTED BY:NANDISH.S

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INTRODUCTION

The word cryogenics literally means production of icy cold.

However, nowadays this term is used as a synonym for the production of low temperatures.

cryogenics is chosen as the field that works below 123 K.

Normal boiling point of most of the gases such as hydrogen,
nitrogen, etc, lies below 123 K.

The area of cryogenics is concerned with the development and
improvisation of systems, processes and techniques that
operate at low temperature.


CRYOGENICS IN SPACE APPLICATIONS:

Sensors used in space applications should be very sensitive to
catch even the weakest signals reaching us from the stars.
Many of these sensors must be cooled to lower temperature to
have the necessary sensitivity.

some of the examples are

Infrared Sensors

Electronics

X-rays


CRYOGENIC LIQUIDS:

Two gases often used in their liquid form as coolant are
Liquid nitrogen
Helium

The boiling point of liquid nitrogen is 77.4 K and triple point
is 63.2 K. Liquid nitrogen is used in many cooling systems.

The boiling point of liquid Helium is 4.224 K. Helium does
not freeze at atmospheric temperature. Only at pressures
above 20 times atmospheric will solid helium will form.

Liquid Helium because of its low boiling point, is used in
many cryogenic systems when temperatures below the boiling
point of nitrogen is needed.


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#8


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INTRODUCTION
The science and technology of deep refrigeration processing occurring at temperature lower than about 150 k. is the field of cryogenics. The name cryogenics is evolved from Greek word ‘Cryos’ meaning icy cold. Phenomena that occurs at cryogenic temperatures include liquefaction and solidification of ambient gases; loss of ductility and embrittlement of some structural materials such as carbon steel; increase in thermal conductivity to a maximum value, followed by further decrease in temperature. Cryogenics is the low temperature (150 K) refrigeration. It explains the properties of cryogens used and their principles. Storage methods and handling techniques are covered.
Cryogenics are applied in different fields of production, transportation, medicine, aerospace, physics research etc. Rocket propulsion is imparting force to a flying vehicle such as missile or spacecraft. Different types of rockets and their parts are explained. Cryogenics has future applications in many fields like superconductivity and propulsion fields. Cryogenics is being applied to variety of research areas; a few of which are: food processing and refrigeration, space craft life supporting system, space simulation, microbiology, medicine, surgery, electronics, data processing and metal working.
The origin of cryogenics as a scientific discipline coincided with the discovery by nineteenth-century scientists that the permanent gases can be liquefied at exceedingly low temperatures. Consequently, the term "cryogenic" applies to temperatures from approximately −100°C (−148°F) down to absolute zero (the coldest point a material could reach). In 1848, English physicist William Thomson (later known as Lord Kelvin; 1824–1907) pointed out the possibility of having a material in which particles had ceased all forms of motion.
The absence of all forms of motion would result in a complete absence of heat and temperature. Thomson defined that condition as absolute zero.

DEFNITIONS AND TYPES
The terms cryogenics, cryobiology, or cryonics are frequently confused. Other new terms with the prefix cryo have also been introduced.
Cryogenics
The branches of physics and engineering that involve the study of very low temperatures, how to produce them, and how materials behave at those temperatures.
Cryobiology
The branch of biology involving the study of the effects of low temperatures on organisms (most often for the purpose of achieving cryopreservation).
Cryonics
The emerging medical technology of cryopreserving humans and animals with the intention of future revival. Researchers in the field seek to apply the results of many sciences, including cryobiology, cryogenics, rheology, emergency medicine, etc.
Cryoelectronics
The field of research regarding superconductivity at low temperatures.
Cryotronics
The practical application of cryoelectronics.
HISTORY
Cryogenics developed in the nineteenth century as a result of efforts by scientists to liquefy the permanent gases. One of the most successful of these scientists was English physicist Michael Faraday (1791–1867). 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.
Six gases, however, resisted every attempt at liquefaction and were known at the time as permanent gases. They were oxygen, hydrogen, nitrogen, carbon monoxide, methane, and nitric oxide. The noble gases—helium, neon, argon, krypton, and xenon—were yet to be discovered. Of the known permanent gases, oxygen and nitrogen (the primary constituents of air), received the most attention.

For many years investigators labored to liquefy air. 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. Oxygen was found to liquefy at 90 K, and nitrogen at 77 K.
Following the liquefaction of air, a race to liquefy hydrogen ensued. James Dewar (1842–1923), a Scottish chemist, succeeded in 1898. He found the boiling point of hydrogen to be a frosty 20 K. In the same year, Dewar succeeded in freezing hydrogen, thus reaching the lowest temperature achieved to that time, 14 K. Along the way, argon was discovered (1894) as an impurity in liquid nitrogen. Somewhat later, krypton and xenon were discovered (1898) during the fractional distillation of liquid argon. (Fractional distillation is accomplished by liquefying a mixture of gases, each of which has a different boiling point. When the mixture is evaporated, the gas with the highest boiling point evaporates first, followed by the gas with the second highest boiling point, and so on.)
Each of the newly discovered gases condensed at temperatures higher than the boiling point of hydrogen but lower than 173 K. The last element to be liquefied was helium gas. First discovered in 1868 in the spectrum of the Sun and later on Earth (1885), helium has the lowest boiling point of any known substance. In 1908, Dutch physicist Heike Kamerlingh Onnes (1853–1926) finally succeeded in liquefying helium at a temperature of 4.2 K.
Words to Know:
Absolute zero: The lowest temperature possible at which all molecular motion ceases. It is equal to −273°C (−459°F).
Kelvin temperature scale: A temperature scale based on absolute zero with a unit, called the Kelvin, having the same size as a Celsius degree.
Superconductivity: The ability of a material to conduct electricity without resistance. An electrical current in a superconductive ring will flow indefinitely if a low temperature (about −260°C) is maintained.


METHODS OF PRODUCING CRYOGENIC TEMPERATURES
Cryogenic conditions are produced by one of four basic techniques:
1. Heat conduction,
2. Evaporative cooling,
3. Cooling by rapid expansion (the Joule-Thomson effect), and
4. Adiabatic demagnetization.
The first two are well known in terms of everyday experience. The third is less well known but is commonly used in ordinary refrigeration and air conditioning units, as well as in cryogenic applications. The fourth process is used primarily in cryogenic applications and provides a means of approaching absolute zero.

HEAT CONDUCTION TECHNIQUE:
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. For example, samples may be cooled to cryogenic temperatures by immersing them directly in a cryogenic liquid or by placing them in an atmosphere cooled by cryogenic refrigeration. In either case, the sample cools by conduction (or transfer) of heat to its colder surroundings.

CRYOTUBES:
Cryotubes used to store strains of bacteria at low temperature. Bacteria are placed in little holes in the beads inside the tubes and then stored in liquid nitrogen.

EVOPARATIVE COOLING TECHNIQUE:
The second process for producing cryogenic conditions is evaporative cooling. Humans are familiar with this process because it is a mechanism by which our bodies lose heat. Atoms and molecules in the gaseous state are moving faster than atoms and molecules in the liquid state. Add heat energy to the particles in a liquid and they will become gaseous. Liquid perspiration on human skin behaves in this way. Perspiration absorbs body heat, becomes a gas, and evaporates from the skin. As a result of that heat loss, the body cools down.
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. Once some given temperature is reached, pumping continues at a reduced level in order to maintain the lower temperature. This method can be used to reduce the temperature of any liquid. For example, it can be used to reduce the temperature of liquid nitrogen to its freezing point or to lower the temperature of liquid helium to approximately 1 K.
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. Once some given temperature is reached, pumping continues at a reduced level in order to maintain the lower temperature. This method can be used to reduce the temperature of any liquid. For example, it can be used to reduce the temperature of liquid nitrogen to its freezing point or to lower the temperature of liquid helium to approximately 1 K.
To cool a gas using the 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.
The Joule-Thomson effect is an important part of our lives today, even though we may not be aware of it. Ordinary household refrigerators and air conditioners operate on this principle. First, a gas is pressurized and cooled to an intermediate temperature by contact with a colder gas or liquid. Then, the gas is expanded, and its temperature drops still further. The heat needed to keep this cycle operating comes from the inside of the refrigerator or the interior of a room, producing the desired cooling effect.

ADIABATIC DEMAGNETIZATION TECHNIQUE:
The fourth process for producing cryogenic temperatures uses a phenomenon known as adiabatic demagnetization. Adiabatic demagnetization makes use of special substances known as paramagnetic salts. A paramagnetic salt consists of a very large collection of particles that act like tiny (atom-sized) magnets. Normally these magnetic particles are spread out in all possible directions. As a result, the salt itself is not magnetic. That condition changes when the salt is placed between the poles of a magnet. The magnetic field of the magnet causes all the tiny magnetic particles in the salt to line up in the same direction. The salt becomes magnetic, too.

At this exact moment, however, suppose that the external magnet is taken away and the paramagnetic salt is placed within a liquid. Almost immediately, the tiny magnetic particles within the salt return to their random, every-which-way condition. To make this change, however, the particles require an input of energy. In this example, the energy is taken from the liquid into which the salt was placed. As the liquid gives up energy to the paramagnetic salt, its temperature drops.
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.

APPLICATIONS

INDUSTRIAL APPLICATIONS:
Cryogenic treatment works on Reamers (carbide or HSS), Tool Bits, Tool Punches (carbide or HSS), Carbide Drills, Carbide Cutters, Milling Cutters, Files, Shaping Equipment, Scissors, Razors, Clippers, Knives, Band Saw Blades, Saw Blades, Reciprocating Blades, Saber Saw, Steel Woodworking and Form Tooling, Cutting Tools and Dies. In all cases, this treatment will result a stronger and more wear resistant metal.
Cryogenic processing
The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. With a background in the heat treating industry, Busch founded a company in Detroit called CryoTech in 1966. Though CryoTech later merged with 300 Below to create the largest and oldest commercial cryogenics company in the world, they originally experimented with the possibility of increasing the life of metal tools to anywhere between 200%-400% of the original life expectancy using cryogenic tempering instead of heat treating. This evolved in the late 1990s into the treatment of other parts (that did more than just increase the life of a product) such as amplifier valves (improved sound quality), baseball bats (greater sweet spot), golf clubs (greater sweet spot), racing engines (greater performance under stress), firearms (less warping after continuous shooting), knives, razor blades, brake rotors and even pantyhose. The theory was based on how heat-treating metal works (the temperatures are lowered to room temperature from a high degree causing certain strength increases in the molecular structure to occur) and supposed that continuing the descent would allow for further strength increases. Using liquid nitrogen, CryoTech formulated the first early version of the cryogenic processor. Unfortunately for the newly-born industry, the results were unstable, as components sometimes experienced thermal shock when they were cooled too quickly. Some components in early tests even shattered because of the ultra-low temperatures. In the late twentieth century, the field improved significantly with the rise of applied research, which coupled microprocessor based industrial controls to the cryogenic processor in order to create more stable results.

Cryogens, like liquid nitrogen are further used for specialty chilling and freezing applications. Some chemical reactions, like those used to produce the active ingredients for the popular statin drugs, must occur at low temperatures of approximately −100 °C. Special cryogenic chemical reactors are used to remove reaction heat and provide a low temperature environment. The freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and brittle at very low temperatures, which makes cryogenic milling (cryomilling) an option for some materials that cannot easily be milled at higher temperatures.
Cryogenic processing is not a substitute for heat treatment, but rather an extension of the heating - quenching - tempering cycle. Normally, when an item is quenched, the final temperature is ambient. The only reason for this is that most heat treaters do not have cooling equipment. There is nothing metallurgically significant about ambient temperature. The cryogenic process continues this action from ambient temperature down to −320 °F (140 °R; 78 K; −196 °C). In most instances the cryogenic cycle is followed by a heat tempering procedure. As all alloys do not have the same chemical constituents, the tempering procedure varies according to the material's chemical composition, thermal history and/or a tool's particular service application. The entire process takes 3–4 days.
Fuels
Another use of cryogenics is cryogenic fuels. Cryogenic fuels, mainly liquid hydrogen, have been used as rocket fuels. Liquid oxygen is used as an oxidizer of hydrogen, but oxygen is not, strictly speaking, a fuel. For example, NASA's workhorse space shuttle uses cryogenic hydrogen fuel as its primary means of getting into orbit, as did all of the rockets built for the Soviet space program by Sergei Korolev. (This was a bone of contention between him and rival engine designer Valentin Glushko, who felt that cryogenic fuels were impractical for large-scale rockets such as the ill-fated N-1 rocket spacecraft.)
Russian aircraft manufacturer Tupolev developed a version of its popular design Tu-154 with a cryogenic fuel system, known as the Tu-155. The plane uses a fuel referred to as liquefied natural gas or LNG, and made its first flight in 1989.

AUTOMOTIVE APPLICATIONS:
Imagine a racer and crew who would normally tear down their engine after every race or two, suddenly discovering a process that would allow them to safely go up to 30 races or more without a major rebuild. Cryogenic treatment of automotive parts can certainly help make this a reality.
Cryogenics works with almost all metal engine parts. Pistons, rings, rockers, push rods, connecting rods, valves, the crank and camshaft and even the block itself. Together, a treated engine can last substantially longer in terms of wear than any other process could achieve. Even parts like brake rotors, drums, and brake pads can benefit from cryogenic treatment. Really, almost any part that is normally subject to wear can benefit. Just imagine what cryogenic treatment would do for the parts in your family vehicle!

MEDICAL APPPLICATIONS:
Cryogenics has also been used by the medical industry. Surgical tools used by doctors, surgeons, dentists, and other specialist’s can all benefit from the increased wear resistance of the treatment. Surgical tools, like many other industrial tools, are expensive to replace, so cryogenic treatment can really pay off.
In addition, many surgical implants are also treated. This helps prevent the part from wearing, it increases the tensile and bending strength of the part, as well as reducing the likelihood of micro fracturing. Cryogenics really is a healthy choice for the medical field.

SPACE APPLICATIONS:
Cryogenic liquids are also used in the space program. For example, cryogenic materials are used to propel rockets into space. A tank of liquid hydrogen provides the fuel to be burned and a second tank of liquid oxygen is provided for combustion. Another space application of cryogenics is the use of liquid helium to cool orbiting infrared telescopes. Infrared telescopes detect objects in space not from the light they give off but from the infrared radiation (heat) they emit. However, the operation of the telescope itself also gives off heat. What can be done to prevent the instrument from being blinded by its own heat to the infrared radiation from stars? The answer is to cool parts of the telescope with liquid helium. At the temperature of liquid helium (1.8 K) the telescope can easily pick up infrared radiation of the stars, whose temperature is about 3 K.

PRODUCTION
Cryogenic cooling of devices and material is usually achieved via the use of liquid nitrogen, liquid helium, or a cryocompressor (which uses high pressure helium lines). Newer devices such as pulse cryocoolers and Stirling cryocoolers have been devised. The most recent development in cryogenics is the use of magnets as regenerators as well as refrigerators. These devices work on the principle known as the magnetocaloric effect.

CRYOGENIC VALVES
Cryogenic carbon steel socket weld globe valve. Valves and are generally made of plastic or steel, the latter being the most widely used in chemical and petrochemical applications. Steel grades range from the most common type, namely carbon steel, with standard stainless steel being the second most common. Stainless steel alloys, which include nickel or copper are used in applications that require higher corrosion or heat resistance. In such cases, the most commonly used valve configurations -- ball valves, gate valves, check valves, globe valves and butterfly valves -- are often forged or cast as duplex valves, super duplex valves, alloy 20 valves, monel valves, inconel valves, incoloy valves and 254 SMO valves (6Mo valves). Titanium valves are also used in some highly corrosive applications. Titanium is not a stainless steel alloy.

ADVANTAGES AND DISADVANTAGES

ADVANTAGES:
Cryogenics can produce large quantities of high purity (parts per billion contaminations) nitrogen. Some processes like the humid-air expansion process have a yield of about 40%-60% per pass, which allows you produce large quantities of nitrogen efficiently. Other processes, like the waste expansion, have a yield of about 25-40% per pass.
Cryogenic processes do not have economics of scale, i.e., expansion or reduction of product quantity requirements generally does not necessitate new equipment.

DISADVANTAGES:
Cryogenic processes in general have very large capital cost, due mostly to the cost of compressors and turbines. The high pressure requirements and the recovery of refrigeration energy explain the need for this equipment. Cryogenic separation requires the use of not only the compressors and turbines, but also numerous heat exchangers, insulators, and a distillation column; all of which add to the high costs of the process.


CONCLUSION
In this seminar report titled “CRYOGENICS” having the methods to produce the cryogenics temperatures and many advantages which are used for industries, automotives, medical field, space crafts, etc...This seminar report has given me more experience and knowledge on the cold generation and helped me to understand what cryogenics is, how it is produced, where it has been used and what is the use of cryogenics.




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#9
PRESENTED BY:
MUNIR SHARIF

[attachment=9510]
INTRODUCTION
• cryogenic may be define as the branch
Of physics which deals with the production of low temperature and theirEffect on matter.
• It may also define as the science and techonology of temperature below the 120k
• The word “cryo” is derived from a Greek word “kruos” which means cold
METHOD TO PRODUCED LOW TEMPERATURE
• Magnetism produced low temperature. when a material is magnitized it become warm and cold when demagnetized in controlled Atmosphere thus producing low temperatures.
• By compressing the gas, the gas is cooled releasing heat and later allowed to expand producing ultra low temperature.
Cryogenics in fuels
• Fluids are stored at 93.5k(-180) or below
• Due to air friction, it gets ignited
• Cool Engine on expansion.
• On expansion pressure increases providing high thrust.
• Satellite payload is increases
Cryogenics rocket engine
• Cryogenic rocket engine are one of the importein application in the field of cryogenics.
• The higher thrust level required for for a rocket engine are achieved when liquid oxygen and liquid hyderocarbon are used as a fuel.but at atmospheric condition,LOX and low molecular hydrocarbon are in gaseous states. Therefore these are stored in liquid form by cooling them down using cryogenics.hence the name cryogenic rocket engine.
GRINDING
Grinding is one of the most popular finishing processes.
 This process is carried out with a grinding wheel made up of grits for removing materials from workpiece surface.
The problems in conventional grinding process:
 High heat generation
 Introduction of tensile residual stress and micro-cracks occur
 High level of surface quality can not be reached
 Problems in hard materials.
 Less tool life
 Sometimes M.R.R. is not satisfactory.
Now… elimination of all those problems are required…
but…
HOW…???
Here comes the introduction of _
C R Y O G E N I C
G R I N D I N G

…also known as Freeze Grinding
How it is done…
The cryogen like liquid nitrogen is applied onto the cutting point mostly in the form of jet. At low temperature (-196°C) of the cryogen, the temperature at the cutting zone is controlled more effectively than the other methods of applying cutting fluid.
Experimental set-up
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