Heat storage material, method for production of heat storage material, and chemical heat pump

Abstract

A heat storage material has a high hydration capacity, which does not readily deliquesce and can be effectively used. A method produces such a heat storage material, and a chemical heat pump and heat storage method use such a heat storage material. The heat storage material is a composite metal halide including a monovalent metal, a divalent metal, and a halogen. The method for producing the heat storage material includes preparing a mixture in which a monovalent metal halide and a divalent metal halide hydrate are mixed, and generating the composite metal halide by subjecting the mixture to a heat treatment. The chemical heat pump includes a water storage unit storing water as a working medium, a heat storage material retention unit retaining the heat storage material, and a water vapor flow path allowing water to flow vapor between the water storage unit and the heat storage material retention unit.

1 . A heat storage material, being a composite metal halide including a monovalent metal, a divalent metal, and a halogen. 
     
     
         2 . The heat storage material according to  claim 1 , wherein the composite metal halide has a perovskite structure of the composition of either Formula (1) or (2) below:
   ABX 3   (1)
     A 2 BX 4   (2)
   wherein A is a monovalent metal, B is a divalent metal, X is a halogen, and A, B, and X may each be one or a combination of a plurality of elements having the same valency.   
     
     
         3 . The heat storage material according to  claim 2 , wherein the composite metal halide has the perovskite structure of the composition of Formula (1). 
     
     
         4 . The heat storage material according to  claim 1 , wherein the monovalent metal is selected from the group consisting of alkali metals and transition metals. 
     
     
         5 . The heat storage material according to  claim 4 , wherein the monovalent metal is selected from the group consisting of potassium and cesium. 
     
     
         6 . The heat storage material according to  claim 1 , wherein the divalent metal is selected from the group consisting of alkaline earth metals and transition metals. 
     
     
         7 . The heat storage material according to  claim 6 , wherein the divalent metal is selected from the group consisting of magnesium and calcium. 
     
     
         8 . The heat storage material according to  claim 1 , wherein the halogen is selected from the group consisting of chlorine, bromine, and iodine. 
     
     
         9 . The heat storage material according to  claim 8 , wherein the halogen is chlorine. 
     
     
         10 . A method for the production of the heat storage material according to  claim 1 , comprising the following steps:
 preparing a mixture by mixing a monovalent metal halide and a divalent metal halide hydrate, and   generating the composite metal halide by subjecting the mixture to a heat treatment.   
     
     
         11 . A chemical heat pump, comprising:
 a water storage unit for storing water as a working medium,   a heat storage material retention unit for retaining the heat storage material according to  claim 1 , and   a water vapor flow path for allowing water vapor to flow between the water storage unit and the heat storage material retention unit.   
     
     
         12 . A heat storage method, comprising performing, in the chemical heat pump according to  claim 11 , heat storage and heat dissipation by hydrating and dehydrating the working medium in the heat storage material.