A thermal energy storage system comprising a working fluid to store and transfer thermal energy between a heat source and a thermal load and a vessel to store the working fluid. The vessel has an interior region and a floating separator piston in the interior region to separate a hot portion from a cold portion of the working fluid. There is a first manifold thermally coupled to an output of the heat source and to an input of the thermal load and fluidly coupled to the interior region of the vessel and a second manifold thermally coupled to an input of the heat source and an output of the thermal load and fluidly coupled to the interior region of the vessel. There is a controller configured to maintain the working fluid in a liquid state.

A heat accumulator device for accumulating sensible heat in molten salts, including: -a heat accumulator vessel for receiving molten salt, a separating layer being disposed in the heat accumulator vessel in order to separate a cold region, in which cold molten salt is present, from a hot region, in which hot molten salt is present, and the cold region being located below the hot region; - a device for loading and unloading the heat accumulator vessel, which device is connected to the cold region and to the hot region; and - a volume compensation device for compensating a temperature-related change in the volume of the molten salt, the volume compensation device interacting with the cold region and/or with the separating layer.

A heat storage device of the present disclosure includes a latent heat storage material and a container. The latent heat storage material is water-soluble. The container houses the latent heat storage material and is formed of a main material being aluminum or an aluminum alloy. The container has a joining portion and a first coating. The first coating covers at least the joining portion on an inner surface of the container. On a surface of the first coating, a first element and fluorine are present. The first element is an element other than aluminum and having a lower ionization tendency than potassium.

The disclosed technology includes methods of extracting geothermal energy, generally comprising the steps of: insertion of a thermal mass into a Heat Absorption Zone, absorbing heat in thermal mass, raising the thermal mass to a Heat Transfer Zone, and transferring the heat from the thermal mass. The acquired heat can be used to generate electricity or to drive an industrial process. The thermal mass can have internal chambers containing a liquid such as molten salt, and can also have structures facilitating heat exchange using a thermal exchange fluid, such as a gas or a glycol-based fluid. In some embodiments, two thermal masses are used as counterweights, reducing the energy consumed in bringing the heat in the thermal masses to the surface. In other embodiments, solid or molten salt can be directly supplied to a well shaft to acquire geothermal heat and returned to the surface in a closed loop system.

The present disclosure relates to techniques for extracting heat energy from geothermal briny fluid. A briny fluid can be extracted from a geothermal production well and delivered to a heat exchanger. The heat exchanger can receive the briny fluid and transfer heat energy from the briny fluid to a molten salt. The molten salt can be pumped to a molten salt storage tank that can serve as energy storage. The briny fluid can be returned to a geothermal source via the production well. The briny fluid can remain in a closed-loop system, apart from the molten salt, from extraction through return to the geothermal production well.

Disclosed are systems and methods of flexibly cooling thermal loads by providing a complex compound system for burst mode cooling, a vapor compression system for ancillary cooling, and a thermal storage system for helping efficiently maintain and cool a thermal load such as a directed energy weapon system.

A thermal energy storage system for comprising a working fluid to store and transfer thermal energy between a heat source and a thermal load and a plurality of vessels to store the working fluid. Each vessel has an interior region and a floating separator piston in the interior region to separate a hot portion from a cold portion of the working fluid. There is a first manifold thermally coupled to an output of the heat source and to an input of the thermal load and fluidly coupled to the interior region of the vessels and a second manifold thermally coupled to an input of the heat source and an output of the thermal load and fluidly coupled to the interior region of the vessels. The vessels are arranged in parallel.

The present disclosure is directed to materials that can be used in a heat storage and transfer, and an improved method for storing thermal energy which includes a high heat capacity thermal energy storage system using pumped or flowing metallic phase change materials (MPCs). Heat is added by pumping a cold fluid of MPCs mixed with a fluid media such as a molten glass and/or salt from a tank through a heat exchanger, solar receiver, or electrical heater cell and returning the heated fluid to a tank, or solid MPCs can be transported physically, or via gas transport such as entrained flow or a circulating fluid bed. In the heat exchanger, heat can optionally be transferred directly to a counterflowing gas or other fluid, or indirectly through heat exchanger walls to a working fluid, which can be steam, CO.sub.2 or sCO.sub.2, He, H.sub.2, process gas, and/or heat transfer fluid. The MPCs (encapsulated MPCs, non-coated MPCs) are solid-liquid and/or solid-solid phase change particles, salts, metals, or other compounds with a melting point between the hot and cold fluid temperatures, and can optionally include high heat capacity, and/or energy absorbing (IR and divisible) nanoparticles.

Heat energy storage systems described in this disclosure can be used for long-term storage of large amounts of thermal energy. In some cases, such systems receive electrical energy from renewable energy sources such as solar panels or wind turbines. Using novel techniques, the heat energy storage systems covert the electrical energy to thermal energy that is stored in hot materials such as molten silicon, molten salts, or any other material that can store large amounts of heat. The heat energy storage systems incorporate extremely good thermal insulation of the thermal energy storage tank that contains the hot materials. The systems are also configured to release thermal energy in an efficient manner to an electricity-producing steam turbine using novel heat exchanger systems and techniques that are described. The energy storage systems described herein have a higher overall real-world efficiency than energy storage systems currently available.

The invention provides a heat-storage medium conveying system for a solar-thermal power plant. The system includes a high-level tank subsystem including a high-level tank used to store the heat-storage medium. The system further includes a heat-storage medium transport subsystem. The high-level tank subsystem is connected with the heat-storage medium transport subsystem. The heat-storage medium transport subsystem includes a low-level tank. A mounting height of the low-level tank is lower than that of the high-level tank. A volume of the low-level tank is smaller than a volume of the high-level tank. The heat-storage medium can enter the low-level tank from the high-level tank partially or completely by its own gravity. The low-level tank is provided with a conveying pump, and the heat-storage medium is pumped out of the low-level tank through the conveying pump. The invention solves the problems such as construction cost, operation and maintenance cost brought about by using the vertical long-shaft submerged molten salt pump, while avoiding the potential safety hazards in the design of large and small tanks or high-level and low-level tanks.