Cryogenic engineering

Cryogenic engineering is a branch of mechanical engineering which deals with cryogenics. and related very low temperature processes such as air liquefaction, cryogenic engines (for rocket propulsion), cryogenic surgery, et cetera. Generally, temperatures below the boiling point of Nitrogen (77°K) comes under the purview of cryogenic engineering. This field of science also looks at what happens to a wide variety of materials from metals to gases when they are exposed to these temperatures.

Cryogenic engineering is nothing but the branch of engineering which uses cryogenics for various domestic, commercial, scientific, medical and defense applications and cryogenics basically deals with the production of very low temperatures and the effects of these temperatures on different substances and materials.Tepperature concerned with cryogenic does not occur in nature,usually below -243.67 degrees Fahrenheit (120 Kelvin) which is used for liquification gases in air like oxygen,hydrogen,nitrogen,methane,argon,helium and neon etc.

For example, the Ground Support Systems at Kennedy Space Center for the Ares-I and Ares-V rockets in support of the NASA manned space program. Another is the DOE's Office of Electric Transmission and Distribution to develop advanced cryogenic refrigeration systems for cooling the next generation of electric power equipment based upon high-temperature superconductors. Cryogenic engineering plays an important role in unmanned aerial vehicle systems, infrared search and track sensors, missile warning receivers, satellite tracking systems, and a host of other commercial and military systems.

Cryogenic engineering has been used to liquefy atmospheric gases such as Oxygen, Hydrogen, Nitrogen, Methane, Argon, Helium, and Neon. The gases are condensed, collected, distilled and separated. Methane is used in liquid natural gas (LNG), and oxygen, hydrogen and nitrogen are used in rocket fuels and other aerospace and defense applications, in metallurgy and in various chemical processes. Helium is used in diving decompression chambers and to maintain suitably low temperatures for superconducting magnets, and neon is used in lighting.

• INTRODUCTION:

Cryogenics has given big impetus to the traditional fields,such as oxygen production for chemistry & metallurgy. But this technology is enhanced day by day & opens the newer divisions for 'Science and Technology' such as 'CRYOGENIC POWER GENERATION'. CRYOGENIC TEMPERATURE have come to be essential in the fields like physics,instrumentation, astronautics,biology and medicine and have been instrumental in the development of specialized fields of cryogenics such as

1. CRYOPHYSICS
2. CRYOELECTRONICS
3. CRYOSURGERY
4. CRYOGENIC ENGINEERING

• Origin Of Cryogenic Engineering:

The word "cryogenic" is derived from the Greek words kruos for frost and genos for origin of creation which gradually refers to the technology and art of producing low temperatures.Cryogenics has come to describe the the study of phenomenon,techniques, and concepts occurring at or pertaining to temperature below 120K. many applications such as POWER ENGINEERING,NUCLEAR ENGINEERING,AEROSPACE TECHNOLOGY,AGRICULTURE, MEDICINE,FOOD PROCESSING needs the gases like oxygen , nitrogen , carbon dioxide, helium, crypton methane, etc . the liquified gases have very low boiling points lying in the cryogenic range. some materials ,when cooled to very low temperatures,some materials show super conductivity and some liquids, superfluidity.

• Applications:

Cryogenic engineering is important because it plays a major role in modern industry and science.Today, cryogenically cooled electrical machines and superconductors are widely used in power generation , instrumentation, transport and some of the newer fields of technology. Large-scale air separation plants use cryogenics to break down air into its component elements for industrial and medical uses. For efficiency the resulting products are frequently transported and stored as cryogenic fluids. Also for the long range space communication , infrared, and laser systems can hardly be overestimated. Magnetic resonance imaging (MRI) systems that use superconducting magnets cooled by liquid helium have become a common feature in modern hospitals.Deep Freezing , Cryogenic condensation, and Cryosorption offer powerful tools for producing ultra high vacuum. recent medical and biological experiments have discovered that,when exposed to cryogenic temperatures, living tissue and biological material show hitherto unknown properties which in fact opens up a very challenging and brilliant fields for researches in biology , medicine and farming.In space technology, cryogenics is found in the liquid hydrogen and oxygen fuels used in rocket engines and in applications such as the Cosmic Background Explorer (COBE) satellite, whose superfluid (He II) cooled sensors have detected remnants of the Big Bang.

• Historical Review:

The history of cryogenics is inseparable from advances in physics. The rapidly growing field of application for low temperatures,on other hand,has been governing developmaents in the field of cryogenic apparatus and plant.before,cryogenic air separation had been dominated the industrial area and was capable of operation down to 70 K. The rapid expansion in the commrcial production of hydrogen and helium systems operating down to 4K The more recent years have seen a massive expansion in the liquefaction , handling , and storage of natural gas. There is steady increase in the consumption of argon,neon and other rare gases. New cryogenic cooling systems have been designed for the superconducting windings of electrical machines and magnets masers and lasers .There have appeared plants to purify gases by low temperature sorption and distillation,high vacuum cryogenic pumps, instruments and apparatus for cryosurgery,etc. in addition to big 'tonnage-production' liquifiers and cryogenerators ,electronics and cryogenic apparatus. Now, 'mycrogenics' is a field in its own right .

References

Book : 1)Theory & Design of Cryogenic Systems by A.Arkharov I.Marfenina Ye.Mikulin http://books.google.com/books/about/Theory_and_design_of_cryogenic_systems.html?id=ReceAQAAIAAJ 2)Cryogenic Enineering by Thomas A. Flynn http://books.google.com/books/about/Cryogenic_engineering.html?id=1OC8zeol7uMC 3)Introduction to Cryogenic Engineering http://www.slac.stanford.edu/econf/C0605091/present/CERN.PDF 4)www.wisegeek.com 5)www.google.com