magnetic refrigeration full report

[project topics]

Magnetic refrigeration technology could provide a Ëœgreenâ„¢ alternative to traditional energy-guzzling gas-compression fridges and air conditioners.They would require 20-30 percent less energy to run than the best systems currently available, and would not rely on ozone-depleting chemicals or greenhouse gases. magnetic refrigeration system works by applying a magnetic field to a magnetic material - some of the most promising being metallic alloys - causing it to heat up.This excess heat is removed from the system by water, cooling the material back down to its original temperature.When the magnetic field is removed the material cools down even further, The primary reson for magnetic refrigeration is the magnetocaloric effect (MCE), discovered by Warburg in 1881. Specifically, the MCE is "the response of a magnetic solid to a changing magnetic field which is evident as a change in its temperature" (Gschneidner)2. When a magnetic field is applied to a magnetic material, the unpaired spins partially comprising the materialâ„¢s magnetic moment are aligned parallel to the magnetic field. This spin ordering lowers the entropy of the system since disorder has decreased. To compensate for the aligned spins, the atoms of the material begin to vibrate, perhaps in an attempt to randomize the spins and lower the entropy of the system again. In doing so, the temperature of the material increases. Conversely, outside the presence of a file, the spins can return to their more chaotic, higher entropy states, and one then observes a decrease in the materialâ„¢s temperature. The warming and cooling process can be likened to a standard refrigerator which implements compressing and expanding gases for variations in heat exchange and surrounding temperature.


read more
http://ocw.mit.edu/NR/rdonlyres/Material..._paper.pdf
http://ipnpr.jpl.nasa.gov/progress_report/42-78/78D.PDF
http://en.wikipediawiki/Magnetic_refrigeration
http://chuden.co.jp/english/corporate/pr...107_1.html
http://ashraedoclib/20070727_Emerging.pdf