Element for a thermal energy storage

Abstract

The invention provides an element for an easily scalable thermal energy storage, distinctive in that the element comprises: an outer shell being a combined casting form and reinforcement, a solid thermal storage medium in the form of hardened concrete, which concrete has been cast and hardened into said outer shell. Method for building and use of the element, and thermal energy storage comprising elements of the invention.

1 . An element for an easily scalable thermal energy storage, the element comprising:
 an outer shell being a combined casting form and reinforcement; and   a solid thermal storage medium in the form of hardened concrete, which concrete has been cast and hardened into said outer shell.   
     
     
         2 . The element according to  claim 1 , wherein the outer shell is a metal shell having a cross section shape which is circular. 
     
     
         3 . The element according to  claim 1 , wherein the outer shell is open in one end, into which open end the fresh concrete has been poured and cast. 
     
     
         4 . The element according to  claim 1 , wherein the outer shell is a corrugated metal shell, with regular corrugations or with bucked surface of the Spiro-type pipe. 
     
     
         5 . The element according to  claim 1 , comprising at least one of:
 a heat exchanger, as means for heat input and output;   an electric heating element, as means for heat input; and   wherein said means have been cast into the concrete and thus embedded into the element.   
     
     
         6 . The element according to  claim 1 , comprising an embedded heat exchanger dimensioned to provide turbulent flow at normal operating conditions. 
     
     
         7 . The element according to  claim 1 , comprising a small diameter pipe heat exchanger, in the form of an open end smaller diameter pipe section arranged inside a larger diameter closed end pipe section. 
     
     
         8 . The element according to  claim 1 , comprising at least one embedded small diameter pipe heat exchanger shaped as U-shaped pipe sections. 
     
     
         9 . The element according to  claim 1 , comprising:
 imbedded means for heat input and output, arranged with connections or ends from one side of the element; and   wherein the outer shell is a steel shell having wall thickness 0.1-1 mm and has been wound and formed into a circular cross section shape from steel bands, likewise a ventilation duct, and it has a bottom lid or cap, and the solid thermal storage medium is an easily castable grouting or concrete mixture having enhanced thermal storage capacity, enhanced thermal conductivity and enhanced resistance against thermally induced cracking, compared to normal construction concrete.   
     
     
         10 . A method of building an element, comprising:
 arranging an outer shell in a vertical position, with an open upper end;   filling grouting or concrete mixture into the outer shell, up to a prescribed level; and   using the outer shell as a combined casting form and reinforcement.   
     
     
         11 . The method according to  claim 10 , comprising:
 arranging means for heat input and output into the outer shell, using spacers and external fixtures as required, before casting; and   filling grouting or concrete mixture up to a prescribed level at which the ends or connections of said means extend up over the top of the element as standing vertical.   
     
     
         12 . The method according to  claim 10 , comprising vibrating the element during casting. 
     
     
         13 . (canceled) 
     
     
         14 . A thermal energy storage, comprising elements according to  claim 1 , a thermally insulated housing, into which housing the elements have been arranged, and means for thermal energy input and output. 
     
     
         15 . The thermal energy storage according to  claim 14 , comprising a heat transfer and storage fluid, or a phase change material, arranged in the housing of the storage, between the elements. 
     
     
         16 . The element according to  claim 8 , wherein the at least one embedded small diameter pipe heat exchanger comprises two U-shaped pipe sections arranged in parallel in the solid thermal storage material. 
     
     
         17 . The element according to  claim 9 , wherein the outer shell is a steel shell having wall thickness of about 0.5 mm.