Micro-magnetocaloric device

Abstract

A magnetocaloric device ( 1 ), comprises: at least one magnetocaloric material ( 5 ) embedded between two heat transfer structures (TD hot , TD cold ); at least one electric source for generating a magnetic field; and at least one hydraulic circuit in which the working fluid flows in a constant direction and which comprises at least one propulsion means ( 6 ) for the working fluid, wherein the heat transfer structures (TD hot , TD cold ) are adapted to control the transfer or transport of heat between the magnetocaloric material ( 5 ) and the working fluid.

1 . Magnetocaloric device ( 1 ), comprising:
 at least one magnetocaloric material ( 5 ) embedded between two heat transfer structures (TD hot , TD cold ; MS hot , MS cold );   at least one electric source ( 2 ) for generating a magnetic field; and   at least one hydraulic circuit in which the working fluid flows in a constant direction and which comprises at least one propulsion means ( 6 ) for the working fluid, wherein the heat transfer structures (TD hot , TD cold ; MS hot , MS cold ) are adapted to control the transfer or transport of heat between the magnetocaloric material ( 5 ) and the working fluid.   
     
     
         2 . The device ( 1 ) according to  claim 1 , wherein the heat transfer structures comprise at least one thermal switch (TD hot , TD cold ) which is adapted to control heat transfer or heat transport from the magnetocaloric material ( 5 ) to the hydraulic circuit and/or from the hydraulic circuit to the magnetocaloric material ( 5 ). 
     
     
         3 . The device ( 1 ) according to  claim 1 , wherein the heat transfer structures comprise at least one multifunctional coating (MS hot , MS cold ) which is adapted to affect the wetting effect of the working fluid, or/and to affect the thermal or velocity boundary layer of the working fluid, or/and to affect the chemical protection of the magnetocaloric material ( 5 ), and/or to affect the mechanical properties of the magnetocaloric material ( 5 ), and/or to affect the effective thermal properties of the magnetocaloric material ( 5 ) and/or the multifunctional coating (MS hot , MS cold ). 
     
     
         4 . The device ( 1 ) according to  claim 1 , wherein the electric source ( 2 ) comprises electric windings ( 4 ), a core ( 3 ) for the manipulation of the magnetic flux direction, and an electric circuit which enables regeneration of magnetic energy. 
     
     
         5 . The device ( 1 ) according to  claim 1 , where the hydraulic circuit with the working fluid is connected to at least one heat exchanger (CHEX, HHEX), such as a heat source or/and a heat sink heat exchanger. 
     
     
         6 . The device ( 1 ) according to  claim 1 , comprising at least one magnetic field source and a plurality of magnetocaloric materials ( 5 ), wherein each magnetocaloric material ( 5 ) is embedded between two heat transfer structures (TD hot , TD cold ; MS hot , MS cold ), and wherein a common hydraulic circuit is provided such that the heat transfer structures (TD hot , TD cold ; MS hot , MS cold ) are adapted to control the transfer or transport of heat between each magnetocaloric material ( 5 ) and the working fluid. 
     
     
         7 . The device ( 1 ) according to  claim 1 , wherein several sub-devices form a cascade system. 
     
     
         8 . The device ( 1 ) according to  claim 2 , wherein the thermal switch (TD hot , TD cold ) comprises at least one thermal switch material which exhibits anisotropy of the thermal conductivity or comprises at least one thermal switch composite material which exhibits anisotropy of the effective thermal conductivity. 
     
     
         9 . The device ( 1 ) according to  claim 2 , wherein the thermal switch (TD hot , TD cold ) is based on mechanical contact by elastomer materials, or liquid crystals, or based on ferrofluids, or magnetorheologic principles, or liquid metals, or electrorheologic principles, or electrowetting principles, or electrophoresis principles, or magnetohydrodynamics, or electrohydrodynamics. 
     
     
         10 . The device ( 1 ) according to  claim 2 , wherein the thermal switch (TD hot , TD cold ) is based on thermoelectric (Peltier or Seebeck), or thermionic, or spincaloritronic (spin Peltier or spin Seebeck) transport effects. 
     
     
         11 . Magnetocaloric device ( 1 ), comprising:
 at least one magnetocaloric material ( 5 ) embedded between two heat transfer structures (TD hot , TD cold ; MS hot , MS cold );   at least one electric source ( 2 ) for generating a magnetic field which enables regeneration of the magnetic energy; and   at least one hydraulic circuit which comprises at least one propulsion means ( 6 ) for the working fluid, wherein the heat transfer structures (TD hot , TD cold ; MS hot , MS cold ) are adapted to control the transfer or transport of heat between the magnetocaloric material ( 5 ) and the working fluid.   
     
     
         12 . Magnetocaloric device ( 1 ) according to  claim 11 , wherein the electric source ( 2 ) comprises an electromagnet ( 3 ,  4 ) and an energy collector device ( 7 ), wherein the electric source ( 2 ) is adapted to charge the energy collector device ( 7 ) when the magnetic field of the electromagnet ( 3 ,  4 ) is turned off, and use the charged energy collector device ( 7 ) for generation of a magnetic field in the electromagnet ( 3 ,  4 ) when the magnetic field is turned on. 
     
     
         13 . Magnetocaloric device ( 1 ) according to  claim 12 , wherein the electric source ( 2 ) further comprises a first switching device (S 1 ) for connecting the electromagnet ( 3 ,  4 ) to the energy collector device for charging the energy colletor device ( 7 ) and a second switching device (S 2 ) for connecting the energy collector device ( 7 ) to the electromagnet ( 3 ,  4 ) for turning on the magnetic field in the electromagnet by releasing the energy stored in the energy collector device ( 7 ) to start the current flow through the electromagnet ( 3 ,  4 ). 
     
     
         14 . Magnetocaloric device ( 1 ) according to  claim 11 , wherein the energy collector device ( 7 ) comprises a battery or a capacitor. 
     
     
         15 . Magnetocaloric device ( 1 ) according to  claim 1 , wherein the magnetic field is generated by at least one electric source ( 2 ) and at least one permanent magnet material, and where the electric circuit enables regeneration of the magnetic energy.