{"id":1341,"date":"2010-09-30T15:03:57","date_gmt":"2010-09-30T15:03:57","guid":{"rendered":"http:\/\/www.joswassink.nl\/insight\/?p=1341"},"modified":"2010-09-30T15:03:57","modified_gmt":"2010-09-30T15:03:57","slug":"magnetic-minibars","status":"publish","type":"post","link":"https:\/\/www.joswassink.nl\/insight\/?p=1341","title":{"rendered":"Magnetic minibars"},"content":{"rendered":"<p><strong>A new material featuring a big  temperature jump when subjected to a magnetic field will enable  competitive magnetic cooling.<\/strong><\/p>\n<div>\n<p>Hotel minibars are probably the first market to adopt  magnetic cooling on a large scale. These machines currently use silent  but very inefficient thermoelectric Peltier cooling. Replacing those  machines by equally silent magnetocaloric fridges would save lots of  energy, while adding to the hotel&#8217;s green credentials.<\/p>\n<p><!--more-->Dr Nguy\u00ean  Th\u00e0n Trung, a former PhD student at the faculty of Applied Sciences, has  developed a material featuring a &#8216;giant magnetocaloric effect&#8217;. Its  temperature rise under the application of a magnetic field is ten times  greater than in other materials. Trung&#8217;s PhD supervisor, Professor Ekkes  Br\u00fcck, says Trung&#8217;s new material is the first of a second generation.  An unnamed industrial partner is even considering introducing  magnetocaloric fridges, based on Trung&#8217;s alloy, on the market next year.<\/p>\n<p>By  applying an intermittent magnetic field, the magnetocaloric effect can  be used for cooling. Switch the field on, and the magnetocaloric  material will heat up. Switch the magnets off, and the temperature will  drop, so that the material can absorb heat from its surrounding. A  clever cycle results in magnetic refrigeration. However, until now, the  effect was too small to compete with the standard compressor-driven  fridges (in which expanding gas will absorb heat, and compressed gas  will release it).<\/p>\n<p>The magic of the new material, an alloy of  manganese, cobalt, and germanium with boron doping, is the  synchronisation of two phase transitions: the magnetic phase change plus  a structural one. \u201cThe material can switch from hexagonal into  orthorhombic crystal structure [&#8216;square&#8217;, ed.] ones\u201d. Prof. Br\u00fcck  explains. When the material changes from hexagonal to orthorhombic,  entropy falls and heat is given off. Normally, this happens at  relatively high temperatures, but by inserting boron atoms into the  crystal, Trung has succeeded in stabilising the hexagonal form at lower  temperatures, and coinciding the structural change with the magnetic  phase change, resulting in a giant magnetocaloric effect.<\/p>\n<p><em>Nguy\u00ean  Th\u00e0n Trung, First-order phase transitions and giant magnetocaloric  effect, PhD supervisor Professor Ekkes Br\u00fcck.<\/em><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A new material featuring a big temperature jump when subjected to a magnetic field will enable competitive magnetic cooling.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,6],"tags":[107,267,268],"class_list":["post-1341","post","type-post","status-publish","format-standard","hentry","category-articles","category-delta","tag-cooling","tag-magnetism","tag-magnetocaloric-effect"],"_links":{"self":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1341","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1341"}],"version-history":[{"count":0,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1341\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1341"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1341"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1341"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}