Thermal energy storage material comprising hydrated compound and water-swollen cross-linked polymer
First Claim
1. In a thermal energy storage material which comprises at least one hydrated compound which has a reversible transition to the anhydrous or a less hydrated form and a minor amount of hydrogel throughout which said compound is dispersed, the improvement comprising that the hydrogel comprises a water-swollen cross-linked polymer formed by cross-linking a synthetic hydrophilic polymer by a covalent cross-linking mechanism.
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Abstract
The thermal energy storage material comprises at least one hydrated compound (such as an inorganic salt) having a reversible transition to the anhydrous or a less hydrated form and a hydrogel, comprising a water-swollen cross-linked polymer formed by cross-linking a synthetic hydrophilic polymer by a covalent cross-linking mechanism, throughout which the compound is dispersed. The hydrogel is made by reacting a water-soluble or water-dispersible synthetic hydrophilic polymer, which is preferably linear and thermoplastic, with a cross-linking agent therefor in an aqueous medium containing the hydrated compound. The hydrophilic polymer, the aqueous medium and the hydrated compound are used in such amounts that the storage material contains a major proportion, by weight, of the hydrated compound and a minor proportion, by weight, of the cross-linked polymer.
33 Citations
11 Claims
- 1. In a thermal energy storage material which comprises at least one hydrated compound which has a reversible transition to the anhydrous or a less hydrated form and a minor amount of hydrogel throughout which said compound is dispersed, the improvement comprising that the hydrogel comprises a water-swollen cross-linked polymer formed by cross-linking a synthetic hydrophilic polymer by a covalent cross-linking mechanism.
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6. In a method of preparing a thermal energy storage material which comprises a hydrogel having dispersed therein a hydrated compound which has a transition temperature to the anhydrous or a less hydrated form in the range 0°
- to 100°
C., the improvement comprising that the hydrogel is formed by reacting a water-soluble synthetic hydrophilic thermoplastic addition polymer having a substantially linear carbon-carbon backbone and active hydrogen atoms in pendant groups thereof with a cross-linking agent therefor in an aqueous medium containing said hydrated compound, such that the resulting hydrogel comprises a water-swollen, covalently cross-linked polymer. - View Dependent Claims (7, 8)
- to 100°
- 9. In a method of extracting heat by passing a fluid in heat-exchange relationship with a thermal energy storage material comprising at least one hydrated inorganic salt selected from the group consisting of sodium sulphate decahydrate, disodium hydrogen phosphate dodecahydrate, sodium thiosulphate pentahydrate, sodium carbonate decahydrate and calcium chloride hexahydrate and a minor amount of a hydrogel throughout which said salt is dispersed, the improvement comprising that the hydrogel comprises a water-swollen cross-linked polymer formed by cross-linking a water-soluble linear synthetic thermoplastic polymer by a covalent cross-linking mechanism.
Specification