Matsushita Electric Industrial Co., Ltd.

Matsushita Reiki Company, Limited

Ryoichi Yamamoto

Shoichi Ishihara

Takahiro Wada

Teijiro Kitao

Jun-ichiro Setsune

Yoshihiro Matsuo

Hiroshi Yoneno

Fumiko Yokotani

Masanari Mikoda

Yoshihiro Asada

A heat storage material comprises a sodium acetate-water system containing at least 53-69% by weight sodium acetate (CH.sub.3 CO.sub.2 Na), wherein said heat storage material is mixed with a thickener comprising polyvinyl alcohol, paraffin and one or two components selected from the group consisting of formaldehyde and acetone, and has stable performance and little change of heat storage capacity even under repeated storage and release of heat.

Heat storage material

A thermal insulator comprises an expanded resin body having embedded therein an evacuated powder insulation portion which consists of fine powder and a container of film-like plastics or a film-like composite of plastics and metal for enclosing the powder. The resin body has been expanded by a Freon gas as a blowing agent. Since a Freon gas has a larger molecular diameter than the constituent gases of air, it is less likely to permeate through the container than air. Thus present invention provides a novel composite insulator which fully utilizes the benefits of vacuum insulation without necessitating a strong and costly material for a vacuum container.

Thermal insulator

This invention relates to a solar energy storage material comprising N,N'-bis(phenylacetyl)indigo dissolved in a polar solvent. Of the indigo derivatives capable of storing the solar energy by the photoisomerization from trans-isomer to cis-isomer of the molecule, all of the compounds obtained so far had an energy storage capacity of only 30 cal or less per 1 g of the compound and also a high thermal isomerization rate from cis form to trans form in solution. Thus, they cannot be called a solar energy storage material of practical value. In the case of the present invention, on the other hand, when N,N'-bis(phenylacetyl)indigo is dissolved in a polar solvent such as acetonitrile, it is possible to store about 60 cal of energy per 1 g of N,N'-bis(phenylacetyl)indigo, and the half-life period of isomerization from cis to trans from in acetonitrile at 17.degree. C. is 1,264 minutes, which is also a satisfactory value for practical application.

Solar energy storage materials

The disclosure is directed to a composite thermal insulator including a Freon gas expanded plastic, and an evacuated powder insulation. The present invention provides a composite thermal insulator light in weight and having a superior heat insulating performance over a long period through replacement of a thick metallic container conventionally used for the evacuated powder insulation and considered indispensable for withstanding a load at one atmospheric pressure and for preventing vacuum leakage, by a film-like plastic container, with activated carbon disposed in it. More specifically, the composite thermal insulator of the present invention includes a Freon gas expanded plastic, a film-like plastic container evacuated to form a vacuum in its interior, and directly contacting and/or covered by the expanded plastic, and activated carbon or inorganic powder containing activated carbon tightly enclosed in the plastic container, light in weight, having a heat conductivity lower than 0.01 kcal/mh.degree.C. and a mechanical strength sufficient for actual use, with almost no variations with time in the heat insulating property.

Composite thermal insulator

This invention is a method for storing light energy using an indigo derivative. Among indigo derivatives capable of storing light energy by the photoisomerization of the molecule from the trans-form to the cis-form, compounds heretofore obtained have been soluble only in expensive solvents such as benzene, toluene, chloroform, carbon tetrachloride and the like and harmful substances. On the other hand, the indigo derivative of this invention has the form of a pyridinium salt, is soluble in water and/or ethanol, and permits employment of safe and inexpensive water and/or an alcohol as a solvent. The indigo derivative of this invention converted from the trans-form to the cis-form by irradiation with sunlight and storing sunlight energy liberates the aforesaid stored energy as heat on addition of a catalyst and/or a heat trigger.

Sunlight-energy-storing method

The heat accumulating material of this invention comprising three components of calcium chloride (CaCl.sub.2), urea [CO(NH.sub.2).sub.2 ] and water (H.sub.2 O) can have varied temperatures of heat accumulating and heat releasing between 15.degree. C. and 29.5.degree. C. by varying the proportion of said three components, and also has a large latent heat. Hence, much expectation can be placed on it as a heat accumulating material for air conditioning. Moreover, by adding BaFeO.sub.3-x (0.ltoreq.x.ltoreq.0.53) as a nucleating agent to the above-mentioned composition, supercooling can be greatly decreased and wider application of this heat accumulating material becomes possible.

Heat accumulating material

A novel latent heat accumulative material capable of accumulating heat in a temperature range best suited for the storage of solar energy was obtained by adding an organic compound or compounds such as urea [CO(NH.sub.2).sub.2 ]to a system consisting of sodium acetate (CH.sub.3 CO.sub.2 Na) and water (H.sub.2 O). Further addition of a crystal nucleus forming material or materials such as sodium pyrophosphate decahydrate (Na.sub.4 P.sub.2 O.sub.7.10H.sub.2 O) to said composition could minimize supercooling and allowed a wider scope of application of the present heat accumulative material.

Heat accumulative material

The heat accumulating material provided according to this invention makes use of the latent heat of fusion of sodium acetate trihydrate, and it comprises, as blended in a system consisting of sodium acetate and water, at least one nucleation catalyst selected from the group of compounds consisting of tetrasodium pyrophosphate, trisodium monohydrogenpyrophosphate, disodium dihydrogenpyrophosphate and monosodium trihydrogenpyrophosphate. In use of this heat accumulating material, the sodium acetate trihydrate would not be overcooled owing to the overcooling preventing function of the nucleation catalyst but is unfailingly crystallized at a temperature close to the fusion point thereof to radiate latent heat of fusion. The overcooling preventing performance of the nucleation catalyst is not deteriorated even if it is subjected to more than 1,000 cycles of repetition of fusion and solidification, and thus the heat accumulating material maintains a very stabilized heat absorbing and radiating capacity.

A supercooling inhibitor comprising a supercooling inhibitor base having all or part of its surface coated with sodium acetate trihydrate. The supercooling inhibitor base comprises one or more members selected from the group consisting of sodium pyrophosphate (Na.sub.4 P.sub.2 O.sub.7), trisodium monohydrogen pyrophosphate (Na.sub.3 HP.sub.2 O.sub.7), disodium dihydrogen pyrophosphate (Na.sub.2 H.sub.2 P.sub.2 O.sub.7), monosodium trihydrogen pyrophosphate (NaH.sub.3 P.sub.2 O.sub.7), sodium pyrophosphate decahydrate (Na.sub.4 P.sub.2 O.sub.7.10H.sub.2 O), and disodium dihydrogen pyrophosphate hexahydrate (Na.sub.2 H.sub.2 P.sub.2 O.sub.7.6H.sub.2 O). The supercooling inhibitor of the present invention is useful for inhibiting the supercooling of sodium acetate trihydrate which is used as a heat regenerating material utilizing heat of fusion.

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Neyagawa, Japan

Ryoichi Yamamoto