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Cryogenics - an Engineering Tool for Textiles and Apparel Volume 8, Issue 1, Spring 2013 Cryogenics - An Engineering Tool for Textiles and Apparel M. Parthiban, M.R. Srikrishnan and S. Viju Department of Fashion, Textile Technology PSG College of Technology ABSTRACT Cryogenics is the study of the production of very low temperature (below −150 °C, −238 °F or 123 K) and the behavior of materials at those temperatures. The word cryogenics stems from Greek and means "the production of freezing cold"; however, the term is used today as a synonym for the low-temperature state. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit, cryogenicists use the absolute temperature scales. These are Kelvin (SI units) or Rankine scale (Imperial & US units). It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but most scientists assume it starts at or below -150 °C or 123 K (about -240 °F). The National Institute of Standards and Technology at Boulder, Colorado has chosen to consider the field of cryogenics as that involving temperatures below −180 °C (-292 °F or 93.15 K). This is a logical dividing line, since the normal boiling points of the so-called permanent gases (such as helium, hydrogen, neon, nitrogen, oxygen, and normal air) lie below −180 °C while the Freon refrigerants, hydrogen sulfide, and other common refrigerants have boiling points above −180 °C. Keywords: cryogenics, material freezing, refrigeration Introduction condition1. Aging, disease, and damage due to cooling low temperature are all Cryogenics is low temperature potentially things that can be repaired by physics: "The branches of physics and nanotechnology and other future molecular engineering that involve the study of very repair technologies. Cryonics will work only low temperatures, how to produce them, and when future medicine has mastered these how materials behave at those repair technologies. It seems inevitable, with temperatures". Cryogenics is important the progress of science, that these repair because rocket fuel (oxygen and hydrogen) technologies will come to exist. Cryonics is must be loaded in as liquids at cryogenic important for people who want to live much temperatures. Cryogenics is also important longer than is possible in the current world for attaining super-conduction and for of medicine. Cryonics is a "lifeboat to the cryogenic tempering of metals for future" from the current "primitive" state of hardening. Even with good preservation of medicine. Cryonics is no so important for body tissues by cooling and vitrification, people who are happy to live to be 70 or 80 future science will be required to cure and want no more of life, even with the presently incurable diseases and to potential of rejuvenation and perfect health. rejuvenate elderly people to a youthful Article Designation: Scholarly 1 JTATM Volume 8, Issue 1, Spring 2013 When people say "cryogenics" what they often really mean is "cryonics", which is "The emerging medical technology of cryopreserving humans and animals with the intention of future revival." Cryonics is important insofar as it can provide a means for people who are living today to live very long lifespans -- perhaps hundreds of thousands of years. DEEP CRYOGENIC Fig 1. Cryogenic valve processing is different from conventional cryogenic processing and requires cooling Cryogenic processing is not a the parts to more than 300° below zero substitute for heat treatment, but rather an compared to about 120° for conventional extension of the heating - quenching - cryogenic processing2. DEEP CRYOGENIC tempering cycle. Normally, when an item is processing is a microprocessor controlled quenched, the final temperature is ambient. dry process, which includes cooling the The only reason for this is that most heat parts at a programmed rate. Soaking the treaters do not have cooling equipment. parts for up to thirty-six hours, and then an There is nothing metallurgically significant additional tempering operation to relieve about ambient temperature. The cryogenic any stress that may remain. During heat process continues this action from ambient treating, steel's micro-structure transforms temperature down to −320 °F (140 °R; 78 K; from austenite to martensite, which makes −196 °C). In most instances the cryogenic the steel much more wear resistant. cycle is followed by a heat tempering However, some small pockets of austenite procedure. As all alloys do not have the may not transform and this does not allow same chemical constituents, the tempering the knives to perform as well as they can. procedure varies according to the material's DEEP CRYOGENIC processing helps chemical composition, thermal history change retained austenite to martensite, and/or a tool's particular service application. completing the transformation process3. The entire process takes 3–4 days. Cryogenic processing Cryogenic production Cryogens, like liquid nitrogen, are Cryogenic cooling of devices and further used for specialty chilling and material is usually achieved via the use of freezing applications. Some chemical liquid nitrogen, liquid helium, or a reactions, like those used to produce the cryocompressor (which uses high pressure active ingredients for the popular statin helium lines). Newer devices such as pulse drugs, must occur at low temperatures of cryocoolers and Stirling cryocoolers have approximately −100°C (about -148°F)4. been devised. The most recent development Special cryogenic chemical reactors are used in cryogenics is the use of magnets as to remove reaction heat and provide a low regenerators as well as refrigerators. These temperature environment. The freezing of devices work on the principle known as the foods and biotechnology products, like magnetocaloric effect5. Cryogenic vaccines, requires nitrogen in blast freezing temperatures, usually well below 77 K or immersion freezing systems. Certain soft (−196 °C) are required to operate cryogenic or elastic materials become hard and brittle detectors. at very low temperatures, which make cryogenic milling (cryomilling) an option Cryogenic Treatment for some materials that cannot easily be A cryogenic treatment is the process milled at higher temperatures. of treating work pieces to cryogenic Article Designation: Scholarly 2 JTATM Volume 8, Issue 1, Spring 2013 temperatures (i.e. below −190 °C (−310 °F)) used on LNG piers to transfer liquefied to remove residual stresses and improve natural gas from LNG carriers to LNG wear resistance on steels. The process has a storage tanks, as are cryogenic valves. wide range of applications from industrial tooling to improvement of musical signal Cryogenic application in textile and transmission. Some of the benefits of apparels cryogenic treatment include longer part life, (a) Liquid ammonia mercerization less failure due to cracking, improved Stable shaping process technology thermal properties, better electrical opens the doors to fashion, a transitory properties including less electrical fantasy determining the form, color, design resistance, reduced coefficient of friction, and new effects of textiles and clothing. This less creep and walk, improved flatness, and process, presently, is typical in fashionable easier machining6. cotton industry products and is also one of the mature technologies developed in textile Cryogenic hardening and fiber industry. The features such as A cryogenic treatment is the process fitness, comfort, easiness to stretch, etc., are of treating work pieces to cryogenic highly desired today. New purified cotton is temperatures (i.e. below −190 °C (−310 °F)) a quality product material made using this to remove residual stresses and improve high technology, that overcomes the wear resistance on steels. The process has a traditional flaws of shrinkage, wrinkled wide range of applications from industrial clothes, and improves dramatically the tooling to improvement of musical signal natural properties of softness, comfort of transmission7. Some of the benefits of cotton. cryogenic treatment include longer part life, Liquid ammonia finishing (or) liquid less failure due to cracking, improved ammonia mercerizing’ refers to the process thermal properties, better electrical that truly revives the cotton through the properties including less electrical expansion of liquid ammonia at an ultra-low resistance, reduced coefficient of friction, temperature inside the fiber. When the less creep and walk, improved flatness, and cotton fiber is treated at -33ø C liquid easier machining. ammonia, ammonia at ultra-low temperature will permeate immediately into the Major Industrial uses crystallographic structure of the fiber. Stress will be released through interior expansion, Liquefied gases, such as liquid which makes the fiber cavity round and nitrogen and liquid helium, are used in many smooth and rearranges the molecular cryogenic applications. Liquid nitrogen is structure, thus the crystallographic structure the most commonly used element in becomes slack and stable. This physical cryogenics and is legally purchasable around change makes the surface of the entire fabric the world. Liquid helium is also commonly smooth and bright, with solid and soft feel, used and allows for the lowest attainable so elasticity and wash-and-wear is fully temperatures to be reached. These liquids achieved. are held in either special containers known The benefits of liquid ammonia as Dewar flasks, which are generally about mercerizing lies in the
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