Method and apparatus for storing and releasing heat by means of a phase change material

Abstract

A method for storing and releasing heat by means of a phase change material. In said method, a phase change is caused in a first heat exchanging device ( 4 ) by supplying heat during a charging process in a storage medium comprising a phase change material in order to store the heat as latent heat in the storage medium, and a phase change is caused in the storage medium while heat is dissipated during a discharging process in the first or another heat exchanging device ( 2 ). The invention is characterized in that at least predominantly non-encapsulated phase change material is used as storage medium, the storage medium is fed to the first heat exchanging device ( 4 ) as a fluid stream or particle stream during the charging process and is discharged when the phase change has been completed, the storage medium is fed to the first or another heat exchanging device ( 2 ) as a fluid stream during the discharging process and is discharged from the heat exchanging device as a fluid stream or particle stream when the phase change has been completed, the storage medium is temporarily stored in a first storage tank ( 1 ) following the charging process and/or in the first or another storage tank ( 3 ) following the discharging process, and the storage medium is actively conveyed and heat is exchanged during the phase change as the charging process and/or the discharging process take/s place. An apparatus for storing and releasing heat by means of a phase change material is also provided.

1 . A method for storing and releasing heat by a phase change material,
 wherein in a charging process causing, a phase change in a storage medium which comprises a phase change material by addition of heat in a first heat-exchange device ( 4 , for storage of the heat in the storage medium as latent heat, and   in a discharging process, in the first heat-exchange device ( 2 ) or another heat-exchange device ( 2 ), causing a phase change in the storage medium with removal of heat,   the storage medium used is at least predominantly unencapsulated phase change material, and   during the charging process, feeding the storage medium to the first heat-exchange device ( 4 ) as a fluid stream or as a particle stream and, after the phase change has been completed, removing the storage medium,   during the discharging process, feeding the storage medium as a fluid stream to the first heat-exchange device ( 2 ) or another heat-exchange device ( 2 ) and, after phase change has been completed, removing the storage medium from the heat-exchange device as a fluid stream or as a particle stream,   temporarily storing the storage medium, after at least one of the charging process or the discharging process in a first storage tank ( 1 ), or temporarily storing the storage medium after the charging process in the first storage tank and after the discharging process in another storage tank ( 3 ),   and during at least one of the charging process or during the discharging process, during the phase change, at the same time proceeding with active transport of the storage medium and the heat exchange.   
     
     
         2 . The method as claimed in  claim 1 , wherein the active transport during at least one of the charging process or discharging process proceeds mechanically by a motor-driven transport of the heat-exchange device ( 2 ,  4 ) and the heat exchange proceeds at least via at least one of motor-driven elements or stationary elements of the motor driven transport. 
     
     
         3 . The method as claimed in  claim 2 , wherein the active transport during the charging process or discharging process proceeds via a screw conveyor. 
     
     
         4 . The method as claimed in  claim 1 , wherein during the discharging process, the storage medium is fed in liquid form, a phase change from liquid to solid proceeds, and the storage medium is removed as the particle stream, and during the charging process, the storage medium is fed as the particle stream, a phase change from solid to liquid proceeds, and the storage medium is removed in liquid form. 
     
     
         5 . The method as claimed in  claim 4 , wherein during the discharging process the storage medium is comminuted at least one of during or after the phase change to the particles in the heat-exchange device ( 2 ). 
     
     
         6 . The method as claimed in  claim 5 , wherein during the charging process, heat is additionally fed to the storage medium after the phase change for additional storage of sensible heat, and during the discharging process, the sensible heat is removed from the storage medium before the phase change. 
     
     
         7 . The method as claimed in  claim 1 , wherein during at least one of the charging process or the discharging process, the heat exchange proceeds by a heat transport fluid. 
     
     
         8 . The method as claimed in  claim 7 , wherein during at least one of the charging process or discharging process, a phase change of the heat transport fluid is caused. 
     
     
         9 . The method as claimed in  claim 1 , wherein the storage medium has particles having a thermal conductivity greater than that of the phase change material. 
     
     
         10 . The method as claimed in  claim 1 , wherein the storage medium includes admixtures that at least one of favor development of granules on transition from the liquid phase to the solid phase, or prevent the development of a high-volume solid phase. 
     
     
         11 . An apparatus for storing and releasing heat by a phase change material, comprising
 a storage medium which comprises a phase change material, and at least one first heat-exchange device ( 2 ), constructed for a discharging process with release of latent heat of the storage medium by a phase change in the first heat-exchange device ( 2 ) and for a charging process with storage of heat as latent heat in the storage medium by a phase change in the first heat-exchange device or further heat-exchange device ( 4 ),   the storage medium comprises at least predominantly unencapsulated phase change material, and   the apparatus is formed in such a manner that, during the charging process, the storage medium is fed to the at least one first heat-exchange device as a fluid stream or as a particle stream and after the phase change has been carried out, the storage medium is removed,   during the discharging process, the storage medium is fed as a fluid stream to the first heat-exchange device ( 2 ) or further heat-exchange device ( 2 ) and after the phase change has been carried out, the storage medium is removed from the heat-exchange device as a fluid stream or as a particle stream,   the at least one heat-exchange device ( 2 ,  4 ) has a transport device to transport the storage medium and is formed in such a manner that, during the phase change, active transport of the storage medium and heat exchange are carried out simultaneously, and   the apparatus comprises at least one storage tank ( 1 ,  3 ) for receiving the storage medium after removal from the at least one first heat-exchange device ( 2 ,  4 ) or the further heat-exchange device ( 2 ,  4 ).   
     
     
         12 . The apparatus as claimed in  claim 11 , wherein at least the transport device of the first heat-exchange device ( 2 ) comprises a motor drive and a driven element for transporting the storage medium during the charging process, and at least one of a motor-driven element or a stationary element of the transport device is constructed for the heat exchange. 
     
     
         13 . The apparatus as claimed in  claim 12 , wherein at least the first heat-exchange device ( 2 ) comprises a screw conveyor. 
     
     
         14 . The apparatus as claimed in  claim 13 , wherein the first heat-exchange device ( 2 ) comprises a comminuter that comminutes the storage medium to particles at least one of during or after the phase change. 
     
     
         15 . (canceled) 
     
     
         16 . The method as claimed in  claim 3 , wherein the screw conveyor has at least one hollow screw. 
     
     
         17 . The method as claimed in  claim 8 , wherein during the discharging process, a phase change of the heat transport fluid from liquid to gaseous is caused by heat given off from the storage medium to the heat transport fluid. 
     
     
         18 . The method of  claim 8 , wherein during the charging process, a phase change of the heat transport fluid from gaseous to liquid is caused by the heat given off from the heat transport fluid to the storage medium. 
     
     
         19 . The apparatus of  claim 12 , wherein each of the heat-exchange devices comprises in each case one conveyor screw.