Flexible heat exchanger

Abstract

The present invention relates to a heat exchanger which comprises a flexible sheet consisting of a porous material, such as polyvinyl alcohol, sandwiched between two liquid impermeable layers, the liquid impermeable layers defining between them and between fluid-tight edges, a liquid transfer space within said sheet and at least one liquid inlet and at least one liquid outlet for respective connection to a source and a drain of a heat transfer liquid, with a flow path defined between the liquid inlet and liquid outlet within said liquid transfer space. According to one embodiment, the heat exchanger is comprised of an internal PVA sheet sandwiched between two layers of adherent, film forming material. According to one preferred embodiment, the film forming material is silicon. The heat exchanger of the present invention is preferably formed into a garment for overlaying a substantial portion of a subject's body, for controlling its body temperature.

1 . A heat exchanger comprising: 
 a flexible sheet comprising a porous material sandwiched between two liquid impermeable layers, the liquid impermeable layers defining between them and between fluid-tight edges, a liquid transfer space within said sheet; and    at least one liquid inlet and at least one liquid outlet for respective connection to a source and a drain of a heat transfer liquid, with a flow path defined between the liquid inlet and liquid outlet within said liquid transfer space.    
     
     
         2 . A heat exchanger according to  claim 1 , wherein said porous material has a porosity of about 30-95%.  
     
     
         3 . A heat exchanger according to  claim 1 , wherein said sheet has an elasticity characterized in about 20-40% elongation with moderate tension.  
     
     
         4 . A heat exchanger according  claim 1 , wherein said porous material is a PVA foam.  
     
     
         5 . A heat exchanger according to  claim 1 , wherein said liquid transfer space has a thickness of about 1-3 mm.  
     
     
         6 . A heat exchanger according to  claim 1 , wherein said liquid impermeable layers are formed by sintering faces of said porous material.  
     
     
         7 . A heat exchanger according to  claim 6 , wherein said sintering results from heating.  
     
     
         8 . A heat exchanger according to  claim 1 , wherein said impermeable layers are formed from an adherent, film forming material.  
     
     
         9 . A heat exchanger according to  claim 8 , wherein said material is a rubber-based hot melt glue.  
     
     
         10 . A heat exchanger according to  claim 8 , wherein said material is a liquid or semi-liquid rubber cured in place.  
     
     
         11 . A heat exchanger according to  claim 1 , wherein said liquid impermeable layers are formed by a liquid impermeable film adhered to the porous material.  
     
     
         12 . A heat exchanger according to  claim 1 , comprising at least two sheets of porous materials attached to one another with an impermeable interface between them, said liquid transfer space is formed within one of said sheets sandwiched with an additional impermeable layer.  
     
     
         13 . A heat exchanger according to  claim 12 , comprising two external layers of porous material sandwiching an internal layer of porous material, there being liquid impermeable interface between each of the external layers and the internal layer, the two liquid impermeable interfaces defining between them said liquid transfer space within the internal layer.  
     
     
         14 . A heat exchanger according to  claim 13 , formed by adhering three sheets of porous material to one another.  
     
     
         15 . A heat exchanger according  claim 1 , wherein said flow path is defined by means of fluid-tight partitions formed within the liquid transfer space.  
     
     
         16 . A heat exchanger according  claim 1 , wherein said at least one liquid inlet and said at least one liquid outlet comprise a respective feed and drain manifold.  
     
     
         17 . A heat exchanger according to  claim 16 , wherein the manifolds comprise a plurality of openings in a liquid duct, communicating with said liquid transfer space.  
     
     
         18 . A heat exchanger according to  claim 17 , wherein said duct is integrally formed with said flexible sheet.  
     
     
         19 . A heat exchanger according to  claim 1 , for controlling a subject's body temperature, the heat exchanger formed into a garment for overlaying substantial portions of said body.  
     
     
         20 . A heat exchanger comprising: 
 a flexible sheet of polyvinyl alcohol (PVA) sandwiched between two liquid impermeable layers, the liquid impermeable layers defining between them and between fluid-tight edges, a liquid transfer space within said sheet; and    at least one liquid inlet and at least one liquid outlet for respective connection to a source and a drain of a heat transfer liquid, with a flow path defined between the liquid inlet and liquid outlet within said liquid transfer space;    said flexible sheet of the heat exchanger being adapted for overlying portions of a body.    
     
     
         21 . A heat exchanger according to  claim 20 , wherein said liquid transfer space has a thickness of about 1-3 mm.  
     
     
         22 . A heat exchanger according to  claim 20 , wherein said impermeable layers are formed from an adherent, film forming material.  
     
     
         23 . A heat exchanger according to  claim 22 , wherein said material is a liquid or semi-liquid rubber cured in place.  
     
     
         24 . A heat exchanger according to  claim 22 , comprising at least two sheets of porous materials attached to one another with an impermeable interface between them, said liquid transfer space is formed within one of said sheets sandwiched with an additional impermeable layer.  
     
     
         25 . A heat exchanger according to  claim 24 , comprising two external layers of porous material sandwiching an internal layer of porous material, there being liquid impermeable interface between each of the external layers and the internal layer, the two liquid impermeable interfaces defining between them said liquid transfer space within the internal layer.  
     
     
         26 . A heat exchanger according to  claim 20 , wherein said at least one liquid inlet and said at least one liquid outlet comprise a respective feed and drain manifold.  
     
     
         27 . A heat exchanger according to  claim 26 , wherein the manifolds comprise a plurality of openings in a liquid duct, communicating with said liquid transfer space.  
     
     
         28 . A heat exchanger according to  claim 27 , wherein said duct is integrally formed with said flexible sheet.  
     
     
         29 . A heat exchanger comprising: 
 a flexible sheet of polyvinyl alcohol (PVA) sandwiched between two silicon impermeable layers, the silicon impermeable layers defining between them and between fluid-tight edges, a liquid transfer space within said sheet; and    at least one liquid inlet and at least one liquid outlet for respective connection to a source and a drain of a heat transfer liquid, with a flow path defined between the liquid inlet and liquid outlet within said liquid transfer space;    said flexible sheet of the heat exchanger being adapted for overlying portions of a body.    
     
     
         30 . A heat exchanger according to  claim 20  or  29 , for controlling a subject's body temperature, the heat exchanger formed into a garment for overlaying substantial portions of said body.