Extraction from large thermal storage systems using phase change materials and latent heat exchangers

Abstract

An energy storage method and apparatus for extraction from large thermal storage systems using phase change materials and latent heat exchangers. This includes thermal heat extraction from, and charging of a large thermal storage tank containing thousands of megawatt hours of thermal energy, using the phase change of heat collection fluid and the phase change of molten phase change material for thermal storage use in generating electricity, steam, or for other industrial processes as implemented in the field of solar energy collection, thermal storage and extraction. The method and apparatus continuously removes thermal resistance that comes from the phase change material allowing operation at a high rate of efficiency. A heat exchanger is provided inside the storage tank thereby reducing heat losses, capital costs and space requirements compared to existing thermal storage systems.

1 . A method of thermal energy storage and extraction for large systems using phase change materials with low thermal conductivity, said method comprising:
 heating a phase change material;   transferring said phase change material to a storage tank having a heat exchange drum and concentric scraper mechanism; and   maintaining fairly constant heat transfer at a surface of said heat exchange drum via said scraper mechanism.   
     
     
         2 . The method as claimed in  claim 1  wherein said scraper mechanism removes solidified phase change material from said surface of said heat exchange drum. 
     
     
         3 . An apparatus for thermal energy storage and extraction within large systems using phase change materials with low thermal conductivity, said apparatus comprising:
 a heat transfer loop for heating a phase change material;   a heat storage loop for transferring said phase change material to a storage tank having a heat exchange drum and concentric scraper mechanism; and   a working loop for maintaining constant heat transfer to working fluid via a surface of said heat exchange drum by way of said scraper mechanism.   
     
     
         4 . The apparatus as claimed in  claim 3  wherein said scraper mechanism removes solidified phase change material from said surface of said heat exchange drum. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . A method of thermal energy extraction and storage, said method comprising:
 placing a molten phase change material in a thermal storage tank;   at least partly submerging a first side of a heat transfer surface within said molten phase change material;   moving heat transfer fluid across a second side of said heat transfer surface such that heat from said molten phase change material transfers from said molten phase change material to said heat transfer fluid;   facilitating constant heat transfer from said molten phase change material to said heat transfer fluid by using a scraper mechanism for removal of solidified phase change material from said first side of said heat transfer surface.   
     
     
         9 . The method as claimed in  claim 8 , said method further including re-heating said solidified phase change material removed from said first side of said heat transfer surface by said scraper mechanism. 
     
     
         10 . The method as claimed in  claim 9  wherein said placing step includes said molten phase change material removed by said scraper mechanism. 
     
     
         11 . (canceled) 
     
     
         12 . The apparatus as claimed in  claim 4  wherein said heat exchange drum is a tubular cylinder formed by an outer drum and an inner drum and said working fluid is located between said outer drum and inner drum. 
     
     
         13 . The apparatus as claimed in  claim 12  wherein said outer drum forms said a heat exchange surface. 
     
     
         14 . The apparatus as claimed in  claim 13  wherein said scraper mechanism is formed by aircraft wires configured so as to rotate about said outer drum. 
     
     
         15 . The apparatus as claimed in  claim 13  wherein said scraper mechanism is formed by metal bars configured so as to rotate about said outer drum. 
     
     
         16 . The apparatus as claimed in  claim 12  wherein said inner drum forms a heat exchange surface. 
     
     
         17 . The apparatus as claimed in  claim 16  wherein said scraper mechanism is formed by an auger configured so as to rotate within said inner drum. 
     
     
         18 . The apparatus as claimed in  claim 4  wherein said heat exchange drum includes at least one hollow disc, said a first heat transfer surface being an external surface of said disc and a second heat transfer surface being an internal surface of said disc, and said disc having an inlet and an outlet for flow of said working fluid therethrough. 
     
     
         19 . The apparatus as claimed in  claim 18  wherein said disc includes a central aperture through which a rotating axle passes and said scraper mechanism is formed by blades mounted on said rotating axle and configured so as to rotate across said external surface of said disc. 
     
     
         20 . (canceled) 
     
     
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