Article for Magnetic Heat Exchange and Method for Manufacturing an Article for Magnetic Heat Exchange

Abstract

An article ( 1 ) for magnetic heat exchange extends in a first direction ( 3 ) and in a second direction ( 5 ) generally axially perpendicular to said first direction ( 3 ). The article ( 1 ) comprises at least one magnetocalorically active phase ( 2 ). The average thermal conductivity of the article ( 1 ) is anisotropic.

1 . An article for magnetic heat exchange, the comprising:
 at least one magnetocalorically active phase, wherein the article extends in a first direction and in a second direction generally perpendicular to the first direction, and wherein the average thermal conductivity of the article is anisotropic such that the average thermal conductivity in the first direction differs from the average thermal conductivity in the second direction.   
     
     
         2 . The article according to  claim 1 , wherein the average thermal conductivity in the first direction is less than the average thermal conductivity of the article in the second direction. 
     
     
         3 . The article according to  claim 1  wherein the first direction corresponds to the thickness of the article, and the second direction corresponds to a direction in a plane of a lateral area extending generally perpendicular to the first direction, and wherein the average thermal conductivity measured over the thickness of the article is less than the average thermal conductivity measured in a direction in the plane of a lateral area of the article. 
     
     
         4 . The article according to  claim 1 ,
 further comprising:
 a magnetocalorically passive phase having a thermal conductivity which is greater than a thermal conductivity of the magnetocalorically active phase. 
   
     
     
         5 . The article according to  claim 4 , wherein the magnetocalorically passive phase comprises a plurality of grains having, on average, a preferred orientation. 
     
     
         6 . The article according to  claim 5 , wherein
 the plurality of grains of the magnetocalorically passive phase comprise an elongate form having a long direction, and a short direction generally perpendicular to the long direction.   
     
     
         7 . The article according to  claim 5 , wherein
 at least some of the plurality of grains of the magnetocalorically passive phase are arranged in the article with a preferred texture.   
     
     
         8 . The article according to  claim 6 , wherein
 the plurality of grains of the magnetocalorically passive phase are arranged in the article so that on average their long direction extends generally perpendicular to the first direction of the article.   
     
     
         9 . The article according to  claim 5 , wherein
 the plurality of grains of the magnetocalorically passive phase are arranged in the article so that on average their short direction extends generally parallel to the first direction of the article.   
     
     
         10 . The article according to  claim 1 , wherein
 the magnetocalorically active phase comprises a plurality of grains arranged in the article with, on average, a preferred orientation.   
     
     
         11 . The article according to  claim 10 , wherein the plurality of grains of the magnetocalorically active phase have, on average, a preferred texture. 
     
     
         12 . The article according to  claim 10 , wherein
 the magnetocalorically active phase comprises a plurality of grains, each having an elongate form with a long direction and a short direction generally perpendicular to the long direction.   
     
     
         13 . The article according to  claim 12 , wherein
 the grains of the magnetocalorically active phase are arranged in the article so that on average the long direction of the grains extends generally perpendicular to the first direction of the article.   
     
     
         14 . The article according to  claim 13 , wherein
 the grains of the magnetocalorically active phase are arranged in the article so that on average the short direction of the grains extends generally parallel to the first direction of the article.   
     
     
         15 . The article according to  claim 10 , wherein the grains of the magnetocalorically active phase comprise a corrosion protection coating disposed thereon. 
     
     
         16 . The article according to  claim 15 , wherein the corrosion protection coating comprises a metal, an alloy, a polymer, a ceramic, or an inorganic compound. 
     
     
         17 . The article according to  claim 15 , wherein the corrosion protection coating comprises Al, Cu, Sn, or a phosphate. 
     
     
         18 . The article according to one  claim 4 , wherein
 the magnetocalorically active phase is disposed in a plurality of first layers interleaved with a plurality of second layers containing the magnetocalorically passive phase.   
     
     
         19 . The article according to  claim 1 , wherein
 the magnetocalorically active phase comprises at least one first layer having a first density, and at least one second layer having a second density, wherein the first density is greater than the second density.   
     
     
         20 . The article according to  claim 19 , wherein the at least one first layer has a first average porosity and the at least one second layer has a second average porosity, wherein the second average porosity is greater than the first average porosity. 
     
     
         21 . The article according to  claim 18 , wherein the at least one first layer and the at least one second layer are arranged in a stack, wherein adjacent layers are in physical contact with one another. 
     
     
         22 . The article according to  claim 18 , wherein the first layers and the second layers each have a thickness extending generally parallel to the first direction of the article and a lateral area extending generally in the second direction of the article. 
     
     
         23 . The article according to  claim 1 , wherein
 the article comprises two or more active portions arranged along the first direction, each portion comprising a magnetocalorically active phase having a different Curie temperature T c .   
     
     
         24 . The article according to  claim 23 , wherein
 the T c  of the active portions increases in the first direction of the article.   
     
     
         25 . The article according to  claim 1 , further comprising:
 at least one thermal barrier having a thermal conductivity which is less than the thermal conductivity of the magnetocalorically active phase.   
     
     
         26 . The article according to  claim 25 , wherein
 a plurality of thermal barriers are arranged at intervals along the first direction of the article.   
     
     
         27 . The article according to  claim 23 , and further comprising
 a thermal barrier having a thermal conductivity which is less than the thermal conductivity of the magnetocalorically active phase, that is arranged between adjacent active portions.   
     
     
         28 . The article according to  claim 1 , wherein the magnetocalorically active phase comprises one or more of Gd, a La(Fe 1-b Si b ) 13 -based phase, a Gd 5 (Si, Ge) 4 -based phase, a Mn(As, Sb)-based phase, a MnFe(P, As)-based phase, a Tb—Gd-based phase, a (La, Ca, Pr, Nd, Sr)MnO 3 -based phase, a Co—Mn—(Si, Ge)-based phase and a Pr 2 (Fe, Co) 17 -based phase. 
     
     
         29 . The article according to  claim 4 , wherein the magnetocalorically passive phase comprises one or more of the elements, Al, Cu, Ti, Mg, Zn, Sn, Bi or Pb. 
     
     
         30 . The article according to  claim 4 , wherein the magnetocalorically passive phase comprises a soft magnetic material. 
     
     
         31 . The article according to  claim 30 , wherein the soft magnetic material comprises one or more of Fe, FeSi, Co, or Ni. 
     
     
         32 . The article according to  claim 1 , further comprising at least one channel in a surface of the article. 
     
     
         33 . The article according to  claim 32 , wherein the channel is adapted to direct the flow of a heat exchange medium. 
     
     
         34 . The article according to  claim 1 , further comprising an outer protective coating. 
     
     
         35 . The article according to  claim 34 , wherein the outer protective coating comprises a polymer or a metal or an alloy. 
     
     
         36 . A heat exchanger, comprising the article according to  claim 1 . 
     
     
         37 . A refrigeration system, comprising the heat exchanger according to  claim 36 . 
     
     
         38 . An industrial, commercial, or domestic freezer comprising the refrigeration system according to  claim 37 . 
     
     
         39 . A method of manufacturing an article according to  claim 4 , comprising:
 providing a magnetocalorically active phase or a precursor of a magnetocalorically active phase,   providing a magnetocalorically passive phase comprising a plurality of particles,   assembling the magnetocalorically active phase or the precursor of a magnetocalorically active phase and the magnetocalorically passive phase,   compacting the magnetocalorically active phase or the precursor of a magnetocalorically active phase and the magnetocalorically passive phase to form an article having an average preferred orientation of at least the plurality of grains of the magnetocalorically passive phase in the article.   
     
     
         40 . The method according to  claim 39 , wherein
 the compacting comprises inducing a preferred orientation of at least the grains of the magnetocalorically passive phase.   
     
     
         41 . The method according to  claim 39  wherein
 the compacting comprises inducing a preferred orientation of at least the grains of the magnetocalorically active phase. 
 
     
     
         42 . The method according to  claim 39 , wherein the average preferred orientation of at least the plurality of grains of the magnetocalorically passive phase or at least the plurality of grains of the magnetocalorically active phase, or both, is produced at least in part by applying a magnetic field to the magnetocalorically passive phase or to the magnetocalorically active phase or to both. 
     
     
         43 . The method according to  claim 42 , wherein
 the magnetic field is applied before the compacting.   
     
     
         44 . The method according to  claim 42 , wherein
 the magnetic field is applied at a temperature less than the Curie Temperature of the magnetocalorically active phase.   
     
     
         45 . The method according to  claim 39 , wherein
 the particles of the magnetocalorically passive phase have on average anisotropic dimensions and the compaction is carried out so that the grains of the magnetocalorically passive phase are on average orientated such that the grains have a long direction perpendicular to the first direction of the article.   
     
     
         46 . The method according to  claim 39 , wherein the average preferred orientation of at least the plurality of grains of the magnetocalorically passive phase is produced at least in part by mechanical deforming the article after the compacting. 
     
     
         47 . The method according to  claim 46 , wherein the mechanical deforming comprises one of more of rolling, swaging, drawing or extruding. 
     
     
         48 . The method according to  claim 39  wherein the assembling of the magnetocalorically active phase and the magnetocalorically passive phase comprises intimately mixing the magnetocalorically active phase and the magnetocalorically passive phase with one another. 
     
     
         49 . The method according to  claim 39  wherein the assembling of the magnetocalorically active phase and the magnetocalorically passive phase comprises alternately arranging layers consisting essentially of the magnetocalorically active phase and layers consisting essentially of the magnetocalorically passive phase. 
     
     
         50 . The method according to  claim 39  wherein
 the compacting of the magnetocalorically active phase and the magnetocalorically passive phase comprises rolling or pressing. 
 
     
     
         51 . The method according to  claim 42 , wherein
 the applying of the magnetic field during compaction magnetically orientates the grains of the magnetocalorically passive phase so that on average the grains have a long direction that is oriented generally perpendicular to the first direction of the article.   
     
     
         52 . The method according to  claim 42 , wherein
 the applying of the magnetic field during compaction magnetically orientates the grains of the magnetocalorically active phase so that on average the grains have a long direction that is oriented generally perpendicular to the first direction of the article.   
     
     
         53 . A method of manufacturing an article for magnetic heat exchange, comprising:
 providing at least one first plate consisting essentially of a magnetocalorically active phase and having a first density,   providing at least one second plate consisting essentially of a magnetocalorically active phase and having a second density, the first density of the first plate being greater than the second density of the second plate,   arranging the first plate and the second plate in a stack.   
     
     
         54 . The method according to  claim 53 , wherein
 the first plate and the second plate are arranged so that they are in physical contact with one another.   
     
     
         55 . The method according to  claim 53 , wherein
 the first plate has a first porosity and the second plate has a second porosity, the second porosity being greater than the first porosity.   
     
     
         56 . The method according to  claim 53 , wherein
 the providing of the at least one first plate comprises compacting particles of a magnetocalorically active phase or particles of a precursor of a magnetocalorically active phase.   
     
     
         57 . The method according to  claim 56 , wherein
 the providing of the at least one second plate comprises compacting particles of a magnetocalorically active phase or particles of a precursor of a magnetocalorically active phase.   
     
     
         58 . The method according to  claim 57 , wherein
 the compacting is conducted so as to produce a lower porosity in the first plate than in the second plate.   
     
     
         59 . The method according to  claim 58 , wherein
 the providing of at least one first plate and the providing of at least one second plate comprises providing a plurality of first plates and a plurality of second plates which are interleaved with one another in a stacking direction of the article.   
     
     
         60 . The method according to  claim 39 , further comprising adding
 one or more of a lubricant, an organic binder or a dispersant to the assembled magnetocalorically active phase or the magnetocalorically passive phase or both.   
     
     
         61 . The method according to  claim 39 , further comprising heating the article during the compacting. 
     
     
         62 . The method according to  claim 61 , wherein the heating forms a
 magnetocalorically active phase from the precursor.   
     
     
         63 . The method according to  claim 39 , further comprising applying an outer protective coating to the article. 
     
     
         64 . The method according to  claim 63 , wherein applying
 the outer protective coating comprises dipping, spraying or electro-deposition.   
     
     
         65 . A climate control device comprising the heat exchanger according to  claim 36 . 
     
     
         66 . An air conditioning system comprising the climate control device according to  claim 65 .