Thermal energy storage using supercritical fluids
AssigneeCalifornia Institute of Technology
InventorGANI B. GANAPATHI
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Abstract
A thermal energy storage system is described employing latent heat storage of a supercritical fluid instead of typical phase change materials. Two fundamental thermodynamic concepts are invoked. First, by using the latent heat of liquid/vapor phase change, high energy density storage is feasible. Second, by operating the thermal energy storage system at a higher pressure, the saturation temperature is increased to operate at molten salt temperatures and above. Beyond the two-phase regime, supercritical operation permits capturing and utilizing heat taking advantage of latent and sensible heat, both in the two-phase regime as well as in supercritical regime while at the same time, reducing the required volume by taking advantage of the high compressibilities.
Claims20
A thermal energy storage apparatus, comprising:
- a pressurized storage vessel;
- a storage fluid within the pressurized storage vessel;
- and
- at least one heat exchanger coupled to the pressurized storage vessel and in contact with the storage fluid to occasionally transfer heat energy between the storage fluid and at least one working fluid;
- wherein the storage fluid changes from a two-phase state to a supercritical state as the heat energy is transferred from the at least one working fluid to the storage fluid and changes back to the two-phase from the supercritical state as the heat energy is transferred from the storage fluid to the at least one working fluid.
A method of storing thermal energy, comprising:
- storing a storage fluid within a pressurized storage vessel;
- and
- occasionally transferring heat energy between the storage fluid and at least one working fluid with at least one heat exchanger coupled to the pressurized storage vessel and in contact with the storage fluid such that,
- the storage fluid changes from a two-phase state to a supercritical state as the heat energy is transferred from the at least one working fluid to the storage fluid, and
- the storage fluid changes back to the two-phase from the supercritical state as the heat energy is transferred from the storage fluid to the at least one working fluid.
A thermal energy storage apparatus, comprising:
- a pressurized storage vessel means for storing a storage fluid means for storing heat energy;
- and
- at least one heat exchanger means for occasionally transferring the heat energy between the storage fluid means and at least one working fluid means for transferring the heat energy, the at least one heat exchanger means coupled to the pressurized storage vessel means and in contact with the storage fluid means;
- wherein the storage fluid means changes from a two-phase state to a supercritical state as the heat energy is transferred from the at least one working fluid to the storage fluid and changes back to the two-phase from the supercritical state as the heat energy is transferred from the storage fluid to the at least one working fluid.
Dependencies are inferred from the claim text.