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 T2 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.

Description

TECHNICAL FIELD[0001]The present invention relates to a method and system for thermal storage.BACKGROUND ART[0002]Various thermal storage techniques for conserving thermal energy have been used effectively to save energies. Meanwhile, recently, hot water supply units that use a CO2 heat pump or a fuel-cell cogeneration system (which will be referred to herein as a “fuel-cell cogene”) have attracted a lot of attention in the art. In order to reduce the sizes of those units and install them more efficiently, development of high-density thermal storage technology is awaited.[0003]Conventional thermal storage techniques are roughly classifiable into sensible heat storage, latent heat storage, and chemical heat storage techniques. According to the sensible and latent heat storage techniques, some loss such as heat exchange loss is inevitable in practice but there is no need to newly apply any thermal energy during the heat release process. That is why theoretically speaking, almost the s...

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Benefits of technology

[0023]According to the present invention, when a thermal storage process is carried out using a hydrate, the second composition and water can be mixed together uniformly during the heat release process, and therefore, the quantity of thermal output can be increased. In addition, the thermal conductivity between the mixture of the second composition and water and the thermal storage material container can be increased. As a result, the thermal output rate can be increased eventually.

[0024]On top of that, the quantity of thermal output can be increased without decreasing the effective thermal storage density in a thermal storage system. Consequently, a smaller thermal storage system than a conventional one can be provided.

Problems solved by technology

However, the heat generated as a result is released into the external air.

Thus, according to the conventional sensible and latent heat storage techniques, the types of usable thermal storage materials are limited by the temperature of the heat source and a high thermal storage density cannot be ensured in a broad temperature range, which is a problem.

Also, if the conventional chemical heat storage is adopted, external energy should be applied during the heat release process and therefore, the amount of substantial heat stored would decrease, which is also a problem.

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