Method of heat accumulation and heat accumulation system

Abstract

A thermal storage method according to the present invention includes the steps of: (A) putting a first composition A, including an n-hydrate (where n is a hydration number) of an inorganic salt in solid phase and having a phase change temperature Tm of 100° C. or less, in a thermal storage material container; (B) heating the first composition A to a temperature T 2 that is higher than the phase change temperature Tm and removing water contained in the first composition A from the thermal storage material container, thereby obtaining a second composition B in which an m-hydrate (where m is also a hydration number and m<n) of the inorganic salt in solid phase and an aqueous solution of the inorganic salt are both included; (C) stopping removing the water from the thermal storage material container on sensing that the second composition B has been obtained; (D) reserving the second composition B; and (E) mixing the second composition B with water, thereby recovering at least a part of the heat that is stored in the second composition B.

1 . A thermal storage method comprising the steps of:
 (A) putting a first composition, including an n-hydrate (where n is a hydration number) of an inorganic salt in solid phase that has a phase change temperature of 100° C. or less, in a thermal storage material container;   (B) heating the first composition to a temperature that is higher than the phase change temperature and removing water contained in the first composition from the thermal storage material container, thereby obtaining a second composition in which an m-hydrate (where m is also a hydration number and m<n) of the inorganic salt in solid phase and an aqueous solution of the inorganic salt are both included;   (C) stopping removing the water from the thermal storage material container on sensing that the second composition has been obtained;   (D) reserving the second composition; and   (E) mixing the second composition with water, thereby recovering at least a part of the heat that is stored in the second composition.   
     
     
         2 . The thermal storage method of  claim 1 , wherein the step (E) includes using a composition, obtained by mixing the second composition with the water, as the first composition. 
     
     
         3 . The thermal storage method of  claim 1 , wherein the volume fraction of solid in the second composition is greater than 0 vol % but equal to or smaller than 90 vol %. 
     
     
         4 . The thermal storage method of  claim 1 , wherein the step (E) includes mixing the second composition with water in liquid phase. 
     
     
         5 . The thermal storage method of  claim 1 , wherein the step (E) further includes running heat recovery water onto a water channel, which is arranged so as to contact with either the surface of the thermal storage material container or a composition obtained by mixing the second composition with water, thereby making a heat exchange between the surface or the composition and the heat recovery water. 
     
     
         6 . The thermal storage method of  claim 1 , wherein the inorganic salt is magnesium sulfate. 
     
     
         7 . The thermal storage method of  claim 1 , wherein the inorganic salt is calcium chloride. 
     
     
         8 . The thermal storage method of  claim 1 , wherein the inorganic salt is calcium bromide. 
     
     
         9 . A thermal storage system comprising:
 a thermal storage material container that contains a thermal storage material as a first composition, including an n-hydrate (where n is a hydration number) of an inorganic salt in solid phase that has a phase change temperature of 100° C. or less;   a thermal storage material heating section for heating the thermal storage material to a temperature higher than the phase change temperature;   a water removal passage for removing water in gas phase from the thermal storage material container;   a sensor for sensing the amount of the water that has been removed from the thermal storage material container through the water removal passage;   a control section for stopping the removal of the water through the water removal passage based on a result of detection done by the detector on sensing that the thermal storage material is a second composition in which an m-hydrate (where m is also a hydration number and m<n) of the inorganic salt in solid phase and an aqueous solution of the inorganic salt are both included;   a water supply channel for supplying water into the thermal storage material container; and   a heat recovery section for recovering at least a part of the heat that has been stored in the thermal storage material.   
     
     
         10 . The thermal storage system of  claim 9 , wherein the water supply channel is used to supply water in liquid phase into the thermal storage material container. 
     
     
         11 . The thermal storage system of  claim 9 , further comprising
 a condensing section for condensing the water in gas phase, which has been removed from the thermal storage material container through the water removal passage, into liquid phase, and   a water reservoir section for reserving the water that has been condensed by the condensing section.   
     
     
         12 . The thermal storage system of  claim 11 , wherein the thermal storage material heating section includes first heating means for heating a heat medium and a first heat exchange section for making a heat exchange between the heat medium that has been heated by the first heating means and the thermal storage material, and
 wherein the condensing section includes a second heat exchange section for making a heat exchange between the water in gas phase, which has been removed from the thermal storage material container through the water removal passage, and the heat medium, on which a heat exchange has already been done by the first heat exchange section with the thermal storage material, thereby recovering a part of the heat of condensation of the water in gas phase.   
     
     
         13 . The thermal storage system of  claim 11 , wherein the sensor is provided for the water reservoir section. 
     
     
         14 . The thermal storage system of  claim 9 , wherein the heat recovery section has a heat recovery water channel for running heat recovery water, and
 wherein the heat recovery water channel is connected to a heat exchange tube that is arranged in contact with either the surface of the thermal storage material container or the thermal storage material itself.