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	Magnetic refrigeration - Wikipedia, the free encyclopedia
		The external magnetic field (+H) causes the magnetic spins of the atoms to align, thereby decreasing the material's magnetic entropy and heat capacity.
		The basic operating principle of an ADR is the use of a strong magnetic field to control the entropy of a sample of material, often called the "refrigerant." Magnetic field constrains the orientation of magnetic dipoles in the refrigerant.
		When the magnetic field is subsequently switched off, the heat capacity of the refrigerant rises again because the degrees of freedom associated with orientation of the dipoles are once again liberated, pulling their share of equipartitioned energy from the motion of the molecules, thereby lowering the overall temperature of a system with decreased energy.
	en.wikipedia.org /wiki/Magnetic_refrigeration (2654 words)

	Refrigeration - Wikipedia, the free encyclopedia
		Refrigeration is defined as the process of removing heat from an enclosed space or from a substance and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature.
		In oil refineries, chemical manufacturing, and petrochemical plants, refrigeration is used to maintain certain processes at their required low temperatures (for example, in the alkylation of butenes and butane to produce a high octane gasoline component).
		Magnetic refrigeration, or adiabatic demagnetization, is a cooling technology based on the magnetocaloric effect, an intrinsic property of magnetic solids.
	en.wikipedia.org /wiki/Refrigeration (2998 words)

	Encyclopedia :: encyclopedia : Magnetic field (Site not responding. Last check: 2007-10-31)
		(The quantum-mechanical spin of a particle produces magnetic fields and is acted on by them as though it were a current; this accounts for the fields produced by "permanent" ferromagnets.) A magnetic field is a vector field: it associates with every point in space a (pseudo-)vector that may vary in time.
		Thus, using special relativity, magnetic forces are a manifestation of electrostatic forces of charges in motion and may be predicted from knowledge of the electrostatic forces and the movement (relative to some observer) of the charges.
		Technically, the magnetic field isn't a vector according to the formal definition, it is a pseudovector: it gains an extra sign flip under improper rotations of the coordinate system.
	www.hallencyclopedia.com /Magnetic_field (1675 words)

	Low-temperature magnetic refrigerator - Patent 4507927
		In the preferred embodiment the magnetic material is contained in a hermetically sealed container which comprises a wheel-shaped part and a rotatable driveshaft enclosing a drivepost perpendicular thereto at the center thereof.
		The magnets 14 and 16 of the preferred embodiment produce a 5 to 7 tesla field in the gap across the U-shaped container in which a wheel-shaped part hereinafter to be described rotates.
		Within the magnetic field, fluid from heat exchanger 94 is moved through a conduit 96 by a pump 98, through a conduit 99 and duct 74, the porous magnetic material of the rim 46, out through duct 76 and through a conduit 100 back to heat exchanger 94.
	www.freepatentsonline.com /4507927.html (3386 words)

	Magnetic refrigeration apparatus with belt of ferro or paramagnetic material - Patent 4704871
		A magnetic refrigerator operating in the 12 to 77K range utilizes a belt which carries ferromagnetic or paramagnetic material and which is disposed in a loop which passes through the center of a solenoidal magnet to achieve cooling.
		The refrigeration apparatus of claim 7 further comprising third and fourth higher temperature fluid manifolds and third and fourth lower temperature fluid manifolds which direct fluid through said material to said thermal load exchange means or heat rejection exchange means as said first and second higher and lower temperature manifolds.
		The refrigeration apparatus of claim 1 further comprising means for directing fluid flow between said first higher and said first lower temperature manifolds to said second higher and said second lower temperature manifolds respectively, to a passage through said ferromagnetic or paramagnetic porous material.
	www.freepatentsonline.com /4704871.html (5041 words)

	DesMoinesRegister.com \| News (Site not responding. Last check: 2007-10-31)
		The new refrigerator uses a special metal that heats up when exposed to a magnetic field, then cools when the magnetic field is removed.
		Magnetic refrigeration removes the most wasteful part of the refrigerator: the compressor.
		The Ames scientists are developing magnetic refrigeration for Astronautics Corp. of America in Madison, Wis., which wants to market the technology to the public.
	desmoinesregister.com /news/stories/c4780940/16898549.html (400 words)

	Attractive advance towards magnetic refrigerator (January 2002) - News - PhysicsWeb (Site not responding. Last check: 2007-10-31)
		Magnetic refrigerants heat up when they are subjected to a magnetic field because the second law of thermodynamics states that the entropy – or disorder – of a closed system must increase with time.
		Magnetic refrigerators have two main advantages over today's commercial devices, which extract heat from a vapour using a compressor: they do not use hazardous or environmentally damaging chemicals, such as chlorofluorocarbons, and they are up to 60% efficient.
		The heating and cooling that takes place in magnetic refrigeration is proportional to the size of the applied magnetic field and the magnetic moments, which are generally largest in rare-earth elements.
	www.physicsweb.org /article/news/6/1/4 (491 words)

	Inside, Feb. 6, 1998
		The new magnetic refrigerator, which is located at the Astronautics Technology Center in Madison, Wis., has been operating for approximately 1,200 hours over the past 12 months, which far exceeds the few hours or days of operation recorded by other units.
		Conventional refrigerators use as heat transfer fluids chlorofluorocarbons, hydrochloro- fluorocarbons or ammonia, which release vapors that are toxic or damaging to the ozone layer.
		Magnetic refrigeration is most appropriate for use in energy- intensive industrial and commercial refrigeration systems, such as large-scale air conditioners and heat pumps, and supermarket refrigeration units.
	www.iastate.edu /inside/1998/0206/refrig.html (726 words)

	Magnetic refrigeration
		A gas-compression system, similar to the one in your refrigerator at home, is then used to further reduce the temperature to minus 253 C (423.4 F).
		Magnetic refrigeration technology takes advantage of the magnetocaloric effect, the remarkable ability of a magnetic material to heat up in the presence of a magnetic field and cool when the field is removed.
		Magnetic refrigeration doesn't use CFCs and, in the case of the Astronautics model, water is used as the heat transfer fluid.
	www.external.ameslab.gov /news/Inquiry/fall97/bigchill.html (1162 words)

	ScienceWeek
		Another important difference between vapor-cycle refrigerators and magnetic refrigerators is the amount of energy loss incurred during the refrigeration cycle.
		However, with the currently available magnetic materials, this high efficiency is only realized in high magnetic fields of 5 T. 3) The heating and cooling that occurs in the magnetic refrigeration technique is proportional to the size of the magnetic moments and to the applied magnetic field.
		Enhancement of the caloric effects associated with magnetic moment alignment may be achieved through the induction of a first-order phase transition, which will result in much higher efficiency of the magnetic refrigerator.
	scienceweek.com /2003/sw030808-4.htm (616 words)

	Magnetic refrigerator successfully tested
		Earlier this fall, the first room-temperature, permanent-magnet magnetic refrigerator was successfully tested by Astronautics Corporation of America, a research partner in the project with Ames Laboratory.
		Instead of ozone-depleting refrigerants and energy-consuming compressors found in conventional vapor-cycle refrigerators, this new style of refrigerator uses gadolinium metal that heats up when exposed to a magnetic field, then cools down when the magnetic field is removed.
		The new magnet can produce a magnetic field nearly twice as high as that produced by the magnet used in the initial refrigerator; this is an important advance since the output and efficiency of the refrigerator is generally proportional to the strength of the magnetic field.
	www.eurekalert.org /features/doe/2001-11/dl-mrs062802.php (737 words)

	The Hindu : 'Next generation refrigeration technology'
		When the magnetic field is removed, the magnetic moments return to their random directions, entropy increases and the material cools.Since the refrigerant is a solid (usually spheres or thin sheets), continuous refrigeration is achieved by using a fluid for heat transfer.
		The unit, however, is run at a fixed field with the magnet operating in the persistent mode.Two magnetocaloric beds composed of gadolinium spheres mounted on a carrier assembly, are alternately inserted in the bore of the magnet.
		One important measure of the expected performance of a magnetic refrigerant material is its refrigeration capacity (RC), which is the amount of energy that can be transferred from the cold sink to the hot sink in on ideal refrigeration cycle.
	www.hinduonnet.com /thehindu/2000/08/31/stories/08310006.htm (910 words)

	Thermag
		It is organized with the support of the International Institute of Refrigeration IIF/IIR in one of the most beautiful regions of Switzerland; at the banks of Geneva lake, facing the imposing French Alps, surrounded by mediaeval castles and beautiful vineyards.
		Magnetic refrigeration is based on the magnetocaloric effect, which was discovered in 1881 by Warburg.
		The magnetic refrigeration and heat pump technology is a green technology (environmentally benign) with the potential to substitute conventional systems, which at present mainly work with HCFC and CFC refrigerants.
	www.thermag.ch (531 words)

	NIST Research Reveals Tiny Iron Supplement Has ‘Chilling’ Effect That Bodes Well for Magnetic Refrigeration
		chamber to measure its promise as a magnetic refrigerant.
		The original material—a gadolinium-germanium-silicon alloy—already is considered an attractive candidate for a room-temperature magnetic refrigerant.
		NIST magnetics researcher Robert Shull, one of the NIST inventors of the new nanocomposite material, notes that the modest addition of iron results in the formation of nanometer-sized magnetic clusters in the gadolinium alloy.
	www.nist.gov /public_affairs/releases/magrefrig.htm (750 words)

	Magnetic refrigerator gets down and homey: Science News Online, Jan. 5, 2002 (Site not responding. Last check: 2007-10-31)
		Magnetic refrigerators and air conditioners promise to be more efficient than conventional ones, says Karl A. Gschneidner Jr.
		Conventional refrigerators compress a volatile gas and then permit it to rapidly expand, pulling heat from the surroundings.
		In contrast, the magnetic device exploits magnetically induced heating and cooling of a powder of the element gadolinium.
	www.sciencenews.org /articles/20020105/fob2.asp (452 words)

	Vitalij Pecharsky
		Von Ranke,P.J., Pecharsky, V.K., Gschneidner, K.A., Jr., and Korte, B.J., "The anomalous behavior of the magnetic entropy in PrNi5", Phys.
		Pecharsky, V.K. and Gschneidner, K.A., Jr., "Tunable magnetic regenerator alloys with a giant magnetocaloric effect for magnetic refrigeration from ~20 K to ~290 K", Appl.
		Magnetic refrigeration, presented at the annual Advisory Board meeting of the Air Conditioning and Refrigeration Center, University of Illinois Urbana-Champaign, November 6, 2002.
	mse.iastate.edu /vitkp (5605 words)

	New Nanomaterial for Future Magnetic Fridges
		Magnetic refrigerators offer significant advantages when compared with current vapor-compression ones, such as gains in energy efficiency, lower cost of operation or elimination of environmentally damaging coolants.
		However, its cooling potential is undercut by significant energy costs exacted during the on-and-off cycling of an applied magnetic field, the process that drives the refrigeration device.
		When exposed to a magnetic field, the gadolinium alloy and other magnetocaloric-effect materials heat up as their spinning electrons align with the field, thereby magnetizing the materials and raising their temperature.
	radio.weblogs.com /0105910/2004/07/20.html (550 words)

	Cars May Be First to Benefit from Magnetic Refrigeration
		Magnetic refrigeration is based on the magnetocaloric effect -- the ability of some metals to heat up when magnetized and cool down when removed from the magnetic field.
		Using these metals as the refrigerant material would provide an environmentally friendly alternative to the volatile liquid chemicals, like chlorofluorocarbons and hydrochlorofluorocarbons, used in traditional vapor-cycle cooling systems.
		The Center for Rare Earths and Magnetics is a member of the Institute for Physical Research and Technology, a consortium of research, technology-development, technology-transfer and technical-assistance centers at ISU.
	www.iprt.iastate.edu /releases1998/crem_carat.html (599 words)

	Cool Magnet: A little bit of iron gives magnetic refrigeration a boost: Science News Online, June 26, 2004 (Site not responding. Last check: 2007-10-31)
		Magnets are big-time materials, finding roles in products ranging from motors to medical-imaging systems.
		When a magnetic-refrigerant material is exposed to a magnetic field, the field forces the spins of electrons in the material to align.
		Each time a magnetic field is applied to the material, it shifts the arrangement of the atoms, changing the material's crystal structure and releasing energy.
	www.sciencenews.org /articles/20040626/fob6.asp (552 words)

	[No title]
		A big upsurge in research has occurred in the past ten years because it appears that magnetic refrigeration can be cost effective and save considerable energy (20 to 30%) over conventional gas compression technology.
		In 1997 we (Astronautics Corp. of America and Ames Laboratory) demonstrated that magnetic refrigeration is a viable technology for near room temperature applications such as large scale building air conditioning, refrigerator/freezer food processing plants and supermarket chillers.
		Most of the recent devices use permanent magnets as the magnetic field source, and thus are aimed at the consumer market for household refrigerator/freezers and air conditioners, and automotive climate control.
	www.uta.edu /physics/main/phys_news/colloquia/vabstract/abstfall03/Gschneidner.doc (286 words)

	CNR-->Institute IMEM :Focus (Site not responding. Last check: 2007-10-31)
		It is due to the variation of the magnetic part of the entropy of the solid, as a consequence of the coupling of the magnetic sublattices with the applied magnetic field (fig.
		As in the compression of a gas, during the isothermal magnetisation process of a ferromagnet (or paramagnet) the entropy is reduced, while, with the successive demagnetisation (as in the gas expansion), the initial entropy value (corresponding to zero field) is restored (figs.
		What made interesting the research in the field of magnetic refrigeration, was the recent discovery of the existence of a relevant MCE (defined giant) in the intermetallic compound Gd5(Si1.8 Ge2.2), where a large variation of the magnetic entropy DSmag = 20 J/kg K was observed at 270 K, for a magnetic field variation of 5T.
	www.cnr.it /istituti/FocusByN_eng.html?cds=052&nfocus=3 (398 words)

	Karl A. Gschneidner
		The new alloys, based on rare earth materials, will be used in new industrial magnetic refrigerators meant to replace conventional freon-based refrigeration systems now used in the petroleum refining and chemical processing industries.
		The paper was entitled New magnetic refrigeration materials for the liquefaction of hydrogen, by K. Gschneidner, Jr., H. Takeya, J. Moorman, V. Pecharsky, S. Malik and C. Zimm.
		Received an Energy 100 Award for research on magnetic refrigeration from the U.S. Department of Energy as one of the 100 discoveries and innovations between 1977 and 2000 that resulted in improvements for American consumers (January 2001).
	mse.iastate.edu /cagey (12683 words)

	MAGNETIC REFRIGERATION (US3841107)
		A magnetic refrigeration system includes thermal transfer means comprising serial arrangement of magnetocaloric elements and a source of magnetic field.
		The serial arrangement comprises a material having a large, negative magnetocaloric effect which cools upon application of a magnetic field; a paramagnetic material in abutting relationship therewith which cools upon removal of a magnetic field; and end elements functioning as thermal switches.
		The magnetic field is caused to move along the serial arrangement, permitting heat to be transferred from a heat source to a heat sink.
	www.delphion.com /details?pn10=US03841107 (234 words)

	Experimental Facilities - IMR
		The purpose of this laboratory is to develop a magnetic refrigeration system that can operate in the range of ambient atmospheric temperatures and to determine the applicability of magnetic refrigeration to practical consumer refrigeration systems.
		The potential advantages of such a system are the prevention of environmental damage caused by harmful working fluids involved in existing systems and the reduction of energy consumption resulting from the significantly improved energy efficiency inherent in the utilization of the magneto-caloric effect.
		Magnetic refrigeration offers a significantly different thermodynamic approach than existing compression refrigeration system since it does not depend upon a condensable working fluid.
	www.gwu.edu /~imr/facilities.htm (447 words)

	Inside, July 23, 1999 (Site not responding. Last check: 2007-10-31)
		If successful, the prototype would be the first magnetic refrigerator capable of sustained operation and generating enough cooling power for commercial applications.
		Water or antifreeze will be used as the heat-transfer fluid between the magnetic refrigerant and the heat exchangers.
		Large-scale applications using magnetic refrigeration, such as commercial air conditioning and supermarket refrigeration systems, could be available in five to 10 years, Gschneidner said.
	www.iastate.edu /Inside/1999/0723/refrig.html (468 words)

	[No title] (Site not responding. Last check: 2007-10-31)
		Magnetic refrigeration, based on the magnetocaloric effect (MCE), has recently been demonstrated to be a promising alternative for vapour-cycle refrigeration.
		Initially randomly oriented magnetic moments are aligned by a magnetic field, resulting in heating of the magnetic material.
		The large entropy change is attributed to a field-induced first-order phase-transition enhancing the effect of the applied magnetic field.
	www.phys.tue.nl /colloq/colloq/2002a/Bruck.html (213 words)

	New magnetic refrigerator
		Initially tested in September at the Astronautics Corporation of America's Technology Center in Madison, Wisconsin, the new refrigerator is undergoing further testing.
		According to Gschneidner, who is also a Professor of Materials Science and Engineering at Iowa State University, the magnetic refrigerator employs a rotary design.
		As the material leaves the magnetic field, it cools further as a result of the magnetocaloric effect.
	www.eurekalert.org /features/doe/2002-01/dl-nmr061702.php (701 words)

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