Heat storage composition, latent heat storage capsules containing said heat-storage composition and temperature control apparatus using said capsules

DETAILED DESCRIPTION OF THE INVENTION An object of the invention, which has been worked out to solve the problems involved in the prior art as mentioned above, is to provide a heat storage composition which consists mainly of calcium chloride hexahydrate and is capable of substantially avoiding the phenomenon of supercooling and absorbing or releasing the latent heat of solidification with certainty at a temperature around the theoretical solidification point.
Another object of the invention is to provide a heat storage composition which is highly stable with respect to phase separation among the elements constituting the heat storage composition, i.
e.
main constituent (calcium chloride hexahydrate), nucleating agent (barium sulfide, etc.
), solidification point modifier (zinc chloride, etc.
) and so on, and can produce a high-level heat storage effect even in repeated use thereof.
A further object of the invention is to provide a flat PCM capsule which contains the above heat storage composition in the sealed state, has an improved structure and makes it possible for the heat storage/release characteristics of the heat storage composition to be utilized efficiently.
A still another object is to provide a temperature control apparatus in which said PCM capsule can be made the most of for temperature control in various hothouses and the like.
Such objects of the invention have been accomplished by providing the constitutions specified in the accompanying claims.
When a heat storage composition consisting substantially of calcium chloride hexahydrate alone is cooled from the molten state, it does not begin to solidify even after passage across its solidification point (about 29.
5.
degree.
C.
) but begins to solidify rapidly at about 20.
degree.
C.
, for instance, as indicated by the solid line in FIG.
1.
The degree of such supercooling varies greatly depending on the rate of cooling and the extent of disturbance of the melt, among others, so that the temperature at which the latent heat is released cannot be specified