Thermomagnetic cycle device

Abstract

A thermomagnetic cycle device includes a magnetocaloric effect element disposed between a high temperature end and a low temperature end, and a medium that that performs heat exchange with the magnetocaloric effect element. A magnetic field modulator periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated. A heat transport device creates a relative movement between the magnetocaloric effect element and the medium. At least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount of the heat exchange during the magnetization period is different from a second heat exchange amount of the heat exchange during the demagnetization period.

What is claimed is: 
     
         1 . A thermomagnetic cycle device comprising:
 a magnetocaloric effect element that is disposed between a high temperature end and a low temperature end and exerts a magnetocaloric effect;   a medium that exchanges heat with the magnetocaloric effect element;   a magnetic field modulator that periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated; and   a heat transport device that creates a relative movement between the magnetocaloric effect element and the medium, wherein   at least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount between the magnetocaloric effect element and the medium during the magnetization period is different from a second heat exchange amount between the magnetocaloric effect element and the medium during the demagnetization period.   
     
     
         2 . The thermomagnetic cycle device according to  claim 1 , wherein
 the at least one of the magnetic field modulator and the heat transport device is configured such that the first heat exchange amount is larger than the second heat exchange amount.   
     
     
         3 . The thermomagnetic cycle device according to  claim 2 , wherein
 the heat transport device is configured to reduce heat exchange between the magnetocaloric effect element and the medium in a reduction period within the demagnetization period.   
     
     
         4 . The thermomagnetic cycle device according to  claim 3 , wherein
 the heat transport device stops flow of the medium in the reduction period at a beginning of the demagnetization period.   
     
     
         5 . The thermomagnetic cycle device according to  claim 2 , wherein
 the magnetic field modulator is configured to:
 increase a strength of the external magnetic field in an increasing period within the magnetization period; and 
 decrease the strength of the external magnetic field in a decreasing period within the demagnetization period, and 
   the increasing period is longer than the decreasing period.   
     
     
         6 . The thermomagnetic cycle device according to  claim 1 , wherein
 the at least one of the magnetic field modulator and the heat transport device is configured such that the first heat exchange amount is smaller than the second heat exchange amount.   
     
     
         7 . The thermomagnetic cycle device according to  claim 1 , wherein
 the at least one of the magnetic field modulator and the heat transport device is switchable between   an acceleration operation mode in which the first heat exchange amount is different from the second heat exchange amount and   a normal operation mode in which the first heat exchange amount is equal to the second heat exchange amount.   
     
     
         8 . The thermomagnetic cycle device according to  claim 7 , further comprising
 a controller that controls the at least one of the magnetic field modulator and the heat transport device, wherein   the controller defines a period of the acceleration operation mode which is executed before the normal operation mode.   
     
     
         9 . The thermomagnetic cycle device according to  claim 8 , wherein
 the controller defines the period of the acceleration operation mode based on an elapsed time of the acceleration operation mode or an observation temperature related to a temperature of the magnetocaloric effect element.   
     
     
         10 . The thermomagnetic cycle device according to  claim 7 , wherein
 the acceleration operation mode includes:
 a cold storage operation mode in which the first heat exchange amount is larger than the second heat exchange amount; and 
 a heat storage operation mode in which the first heat exchange amount is smaller than the second heat exchange amount, and 
   the at least one of the magnetic field modulator and the heat transport device is switchable between the cold storage operation mode and the heat storage operation mode.