Thermal energy storage and release utilizing combined sensible heat and latent heat of fusion

Claim 1

The method for storing and releasing thermal energy comprising the steps of: employing as the medium into which thermal energy is to be absorbed and from which said thermal energy is to be removed a two phase, two component system having a phase diagram including a liquidus, the phases employed being liquid and solid and one of said components being water with the second component being a hydrate-forming salt; adjusting the amounts of the two components and the temperatures of the resulting medium such that said medium is a saturated aqueous solution having initial temperature-composition values coinciding with a first temperature-composition point on said liquidus; removing thermal energy from said medium to reduce the temperature thereof and simultaneously nucleating the formation of hydrate crystals of the second component at substantially said first temperature-composition point after which as the removal of thermal energy continues hydrate crystals continue to form and the temperature-composition values of said medium change proceeding along said liquidus to some predetermined temperature-composition point at a lower temperature than the temperature of said first temperature-composition point; heating said medium to increase the temperature thereof to redissolve said hydrate and cause said medium to approach said initial temperature-composition along said liquidus; repeating the temperature cycling of the previous steps whereby the sensible heat of water and the heat of fusion of said hydrate-forming salt are simultaneously employed in the thermal energy storage and retrieval; and stirring said medium during said temperature cycling to induce inter-particle motion to hydrate crystals present therein sufficient to maintain said medium in equilibrium whereby said temperature cycling occurs substantially only along said liquidus.

Claim 2

The method for storing and releasing thermal energy comprising the steps of: employing as the medium into which thermal energy is to be absorbed and from which said thermal energy is to be removed a two phase, two component system having a phase diagram including a liquidus, the phases employed being liquid and solid and one of said components being water with the second component being a hydrate-forming salt; adjusting the amounts of the two components and the temperatures of the resulting medium such that said medium is a saturated aqueous solution having initial temperature-composition values coinciding with a first temperature-composition point on said liquidus; removing thermal energy from said medium to reduce the temperature thereof and simultaneously nucleating the formation of hydrate crystals of the second component at substantially said first temperature-composition point after which as the removal of thermal energy continues hydrate crystals continue to form and the temperature-composition values of said medium change proceeding along said liquidus to some predetermined temperature-composition point at a lower temperature than the temperature of said first temperature-composition point; heating said medium to increase the temperature thereof to redissolve said hydrate and cause said medium to approach said initial temperature-composition along said liquidus; repeating the temperature cycling of the previous steps whereby the sensible heat of water and the heat of fusion of said hydrate-forming salt are simultaneously employed in the thermal energy storage and retrieval; and stirring said medium during said temperature cycling to induce inter-particle motion to hydrate crystals present therein sufficient to maintain said medium in equilibrium whereby said temperature cycling occurs substantially only along said liquidus.