Thermal energy storage system

Abstract

A system that allows an efficient heat pump, storage of thermal energy, and extraction of the stored thermal energy as electrical energy as needed. The system operates in two operating modes: a charging operating mode in which thermal energy is pumped in the electrically driven compressor and transferred through the heat transfer liquid into the thermal heat transfer liquid reservoir; and a release mode of operation in which thermal energy from the thermal reservoir is used in the turbine to generate kinetic energy, which can be used directly or converted to electrical energy for use when needed.

Description

Technical Field

[0001] The present disclosure is in the field of heat-based storage systems for allowing the extraction of electrical energy and the controlled use of this energy.

[0002] background

[0003] Prior art heat engines include the Carnot Stirling and Ericsson thermodynamic cycles, all of which reach the Carnot efficiency limit when converting heat energy into work (electricity) through an isothermal process. Conventionally, heat cycles include a compressor and a turbine based on an adiabatic process, such as in the Rankine and Brayton cycles. In the reverse process, the heat engine converts work into heat that can be stored. A Carnot cell is a cycle in which work, such as electricity, is converted into heat storage that is recycled back into electrical energy. To the best of our knowledge, all implementations of the Carnot cell have limited efficiency. The following is an example of a charge-discharge Brayton cycle (see also Figure 1 ): The system includes a high-temperature (H-HEX) thermal energy storage device and a low-temperature (C-HEX) thermal energy storage device, as well as a heat exchanger, a compressor, and a turbine. The entire system is thermally insulated. During the charging process, electricity operates the compressor, which compresses the gas and raises its temperature to a high temperature. The thermal energy is stored in the H-HEX. The compressed air is cooled in the heat exchanger and passes to the turbine to release the pressure. The turbine power returns to the compressor. The exiting gas is cold and passes through the C-HEX to reduce the temperature of the cold storage device. The gas continues to enter the compressor for another cycle. The result of the charging process is a temperature change between the two thermal energy storage devices. During the discharge process, the cold air from the cold storage device is compressed and heated and passes through the hot storage device, where the temperature of the cold air increases (while the storage device is cooled). The hot compressed gas reaches the turbine, generating power, which both drives the compressor and produces output power. After the turbine, the cold gas reaches a cold reservoir and returns to the compressor for another cycle, until the temperature difference between the two reservoirs results in negative power generation. The challenge with this concept is that the thermal energy density is very low, resulting in significant device size and cost. Heat exchangers are also expensive. Expansion and compression are adiabatic, which is inefficient due to the excessive heat relative to the reservoir temperature. Furthermore, due to the high operating temperature, the addition of low-grade waste heat is ineffective in improving round-trip efficiency. Background Art

[0004] References believed to be relevant to the presently disclosed subject matter are listed below as background:

[0005] -WO 2022 / 049573

[0006] -WO 2022 / 234554

[0007] Acknowledgment herein of the above-identified references should not be inferred as meaning that these references are in any way relevant to the patentability of the presently disclosed subject matter. Summary of the Invention

[0008] The present disclosure provides a system for realizing a high-efficiency heat pump, storage of thermal energy, and extraction of the stored thermal energy as electrical energy on demand. Thus, the system operates in two operating modes: (1) a charging operating mode, in which thermal energy is pumped in an electrically driven compressor and transferred to a thermal HTL reservoir (also referred to herein as simply "thermal reservoir") via a heat transfer fluid (HTL); and (2) a discharging operating mode, in which thermal energy from the thermal reservoir is used in a turbine to generate kinetic energy that can be used directly or converted into electrical energy for use when needed. In addition to its role as a carrier of thermal energy, the HTL actively participates in the compression process within the compressor in the charging mode of the system and the expansion process that occurs within the turbine in the discharging mode of the system. The temperature of the thermal reservoir is higher than the ambient temperature, typically much higher than the ambient temperature, for example 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 150°C, 200°C, or even more than the ambient temperature. The degree to which the thermal storage device heats up during the charging of energy and the degree to which the thermal storage device cools down during the discharge of energy depend, inter alia, on the thermal capacity of the thermal storage device.

[0009] In some aspects and embodiments of the present disclosure, a cold HTL reservoir (also referred to herein as a "cold reservoir") is also used, and heat is pumped from the cold reservoir to the hot reservoir or released from the hot reservoir to the cold reservoir during corresponding heat storage and heat utilization. The temperature of the cold reservoir is lower than the ambient temperature, typically significantly lower than the ambient temperature, for example, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 150°C, 200°C, or even more below the ambient temperature. The degree of cooling of the cold reservoir during energy storage and the degree of heating of the cold reservoir during energy release depend, among other things, on the thermal capacity of the hot reservoir.

[0010] According to some embodiments of the present disclosure, the hot reservoir and the cold reservoir can be insulated. Both the compression process and the expansion process involve mixing the working fluid (WF) flowing in the system with the HTL to form a two-phase mixture of WF and HTL (which may be referred to as a "HTL / WF mixture" in this article). In the compressor, WF enters the mixture in its gaseous state (the terms "gas", "gaseous", etc. used in this article include gas and steam) and is compressed, while in the turbine, WF enters the mixture as a compressed gas or in its liquid phase, and is optionally further compressed in the mixture. In the HTL / WF mixture, the HTL component generally accounts for a larger proportion. When the HTL / WF mixture is formed or shortly after the HTL / WF mixture is formed, the temperatures of the HTL and WF are approximately the same because the HTL cools or heats the WF during the corresponding compression or expansion of the WF. It should be noted that the heat capacity of the HTL is much greater than that of the gaseous WF (the heat capacity of the HTL may be about 3 orders of magnitude greater than that of the gaseous WF). As a result, the WF reaches the temperature of the HTL, and the WF expands in the turbine or is compressed in the compressor with essentially no temperature change. This is referred to herein as "quasi-isothermal expansion" and "quasi-isothermal compression," respectively (the term "quasi" refers to the fact that if the temperature is measured very accurately during the process, only small temperature changes can be recorded due to the large heat capacity of the HTL). During the quasi-isothermal process, the temperature at the end of the WF expansion or compression deviates from the initial WF temperature in degrees Kelvin by less than 20%, 10%, 5%, 4%, 3%, 2%, or even less than 1%.

[0011] Thus, during the compression process, the HTL continuously cools the WF in the HTL / WF mixture as heat is transferred from the WF to the HTL, thereby producing the pseudo-isothermal compression of the WF in the HTL / WF mixture. At the end of the compression process, the WF may be in either the gaseous or liquid phase. At the end of the compression process, the HTL and WF are separated in a separation zone, for example, by gravity separation, centrifugal separation, or any other known or suitable separation technique. Therefore, the compressor used herein is a two-phase compressor, i.e., a compressor that operates on a mixture of one material in the liquid phase, i.e., the HTL, and another material in the gaseous phase, i.e., the WF.

[0012] Similarly, during the expansion process in the turbine, the HTL continuously heats the WF in the HTL / WF mixture, thereby producing the aforementioned quasi-isothermal expansion of the WF in the HTL / WF mixture. At the end of the expansion process, the HTL and WF are separated in a separation zone, for example, using one of the separation methods described above. Therefore, for the same reasons as the definition of a compressor and a two-phase compressor, the turbine of the present disclosure is a two-phase turbine.

[0013] According to some embodiments, as further discussed below, the HTL and the WF can be the same substance in different phases, particularly the same substance in different phases in the compressor. According to one embodiment, the compressor has its own HTL, which is referred to as the compressor HTL that flows in a closed loop in the compressor throughout the application, and the WF that is mixed with the compressor HTL can be the same material, but in a different phase. During the compression process in the compressor, the pressure of the compressor HTL drops in a very short time, thereby not allowing the compressor HTL to change its phase to a gas, while allowing the gas phase WF to be sucked in to mix with the compressor HTL. Therefore, the WF and the compressor HTL can be the same material, but in different phases during the compression process in the compressor. When the compressor has its own compressor HTL that is different from the hot HTL, the compressor HTL is heated during the compression process and then its heat is transferred to the hot HTL reservoir by any suitable thermal connection.

[0014] In some other embodiments, the compressor is fed by HTL from a hot HTL reservoir. Thus, in these embodiments, the hot HTL circulates between the hot HTL reservoir and the compressor, being heated each time it circulates, and thereby heating the hot HTL reservoir.

[0015] In some embodiments of the system of the present disclosure, the flow path of each of the HTL and the WF may be the same in the two operating modes. In some other embodiments of the system of the present disclosure, the flow path of each of the HTL and the WF may be the same, but in opposite flow directions. In still other embodiments of the system of the present disclosure, the HTL and the WF have different flow paths in the two operating modes of the system of the present disclosure: (1) in the charging mode, the HTL circulates between the thermal reservoir and the compressor, and the WF circulates between the compressor and the evaporator; (2) in the discharging mode, the HTL circulates between the thermal reservoir and the turbine, and the WF circulates between the turbine and the condenser. In some embodiments, the same flow path is used in the two operating modes, but it is in opposite flow directions.

[0016] The present disclosure provides three system aspects described below, referred to as the "first system aspect," the "second system aspect," and the "third system aspect." While the systems of the second and third system aspects also include a cold reservoir, the system of the first system aspect does not include such a reservoir. In the system of the first system aspect, heat can be exchanged with the environment or an external medium (e.g., a body of water) via a WF medium, and in a charging operating mode, heat is absorbed from the environment or external medium, and in a releasing operating mode, heat is released to the environment or external medium. In the systems of the second and third system aspects, in a charging operating mode, heat is pumped between the cold reservoir and the hot reservoir via the WF medium, and vice versa in a releasing operating mode.

[0017] The second and third system aspects differ in that in the third system aspect, the WF is liquid / vapor phase changing (LVPhC).

[0018] A first system aspect provides a system for storing and extracting electrical energy. The system includes a two-phase turbine and a two-phase compressor. The compressor is configured to compress a compressor HTL. The compressor HTL can be the same as or different from the heat HTL. The system can also include a compressor HTL reservoir. The compressor HTL reservoir can be configured as a component within the compressor that stores compressor HTL before and / or after the compression process in the compressor, or it can be a separate component fluidically connected to the compressor, configured, for example, to replenish compressor HTL wasted during compressor operation.

[0019] The system of the first system aspect also includes a hot HTL reservoir that holds hot HTL. The HTL can be any material (which itself can be a mixture) that maintains a liquid phase across the entire range of operating temperatures and pressures of the system. As described above, according to some embodiments, the HTL can be the same material as the WF, but it remains in a liquid phase due to the shorter duration of the pressure drop in the compressor. The hot HTL reservoir is configured to receive or discharge the hot HTL in corresponding charging and discharging operating modes and can include a material other than the HTL that can receive and store thermal energy transferred from the HTL, such as stone or gravel. In the corresponding discharging or charging operating modes, the hot HTL reservoir can be selectively fluidically connected to a pseudo-isothermal two-phase turbine or a pseudo-isothermal turbine, or in some embodiments, the hot HTL reservoir is thermally coupled only to a two-phase compressor, an insulated two-phase compressor, to supply the hot HTL to the corresponding turbine or compressor, or to allow heat exchange between the compressor HTL and the hot HTL reservoir. In other words, the system is configured to connect the hot HTL reservoir to the compressor in charging mode and to the turbine in discharging mode.

[0020] The compressor and turbine are usually insulated.

[0021] In this specification, reference to an element should be understood to mean that there is at least one such element. In other words, the terms "one", "an" or "the" when referring to an element of a system should be understood to mean at least one such element. For example, a system may include one or more turbines operating in parallel or one or more compressors operating in parallel. Similarly, as another example, the system of the present disclosure may include one heat exchanger unit or multiple such units. The same applies to, for example, condensers, evaporators, reservoirs and all other mentioned elements. To simplify the description, reference to one such element, such as a turbine, compressor, heat exchanger, condenser, evaporator, reservoir, etc., should be understood to mean at least one turbine, at least one compressor, at least one heat exchanger, at least one condenser, at least one evaporator, at least one reservoir, etc. In the case where the system of the present disclosure includes more than one defined element, multiple such elements may operate in series or in parallel, depending on the specific circumstances.

[0022] The system of the first system aspect further comprises a condenser in fluid communication with the turbine, the condenser being configured to receive and condense the WF from the turbine; ie, in the discharge mode of the system, the condenser is located downstream of the turbine in the flow path of the WF.

[0023] The system of the first system aspect optionally further includes a working fluid pump (WF pump) in fluid communication with the condenser for pressurizing the condensate WF condensed in the condenser. It should be noted that the WF pump can be disposed in various locations in the WF flow path, for example, the WF pump can be disposed in the condenser and become an integral part of the condenser, or can be disposed in the flow path between the condenser and the first heat exchanger or between the first heat exchanger and the turbine.

[0024] According to some embodiments, the system of the first system aspect may further include an evaporator in fluid communication with the compressor for receiving and evaporating the WF from the compressor. The evaporator may be the same or a different component as the condenser. That is, in the system's charging operating mode, the evaporator is located downstream of the compressor in the WF flow path. In some embodiments, the condenser and the evaporator are the same component. The condenser / evaporator may be configured to allow heat exchange between the WF flowing through them and its surrounding environment.

[0025] The energy release mode of the system defines the first flow path of the WF, and the energy charging mode defines the second flow path of the WF. In some embodiments, the elements constituting the first WF flow path are used for dual purposes and are also part of the second WF flow path. This may also be true for conduits (e.g., in the form of pipes) that can be used dually in both the first flow path and the second flow path (sometimes at opposite WF flows). This may also be true for other elements, such as the first counter-current heat exchanger and the second counter-current heat exchanger defined below, which may be the same elements used in the two flow paths, or a condenser that can be configured to also serve as an evaporator in the opposite WF flow path.

[0026] According to some embodiments of the system of the first system aspect, the system includes a first counter-flow heat exchanger, typically a regenerator, which can be arranged in the first flow path between the turbine and the condenser and is configured to exchange heat between the WF exiting from the turbine and the WF exiting from the condenser.

[0027] According to some embodiments of the system of the first system aspect, the system includes a second counter-flow heat exchanger of the system, typically a regenerator, which can be the same or a different element as the first heat exchanger, which can be arranged in the second flow path between the compressor and the evaporator and is configured to exchange heat between the WF leaving the compressor and the WF leaving the evaporator.

[0028] The flow paths of WF in the discharge and charge modes of operation of the first system aspect will now be described.

[0029] In the energy release mode, according to one embodiment of the first system aspect of the present disclosure, WF flows in a first flow path to one or more nozzles in the turbine, thereby mixing the WF with HTL to form an HTL / WF mixture. During this flow, the WF may pass through a first heat exchanger. The WF may be LVPhC WF. The HTL / WF mixture undergoes quasi-isothermal expansion in the one or more nozzles, i.e., expansion, wherein the WF remains at approximately the same temperature due to heat exchange with the HTL, which has a much larger heat capacity. In other words, the cooling of the WF during the expansion process has minimal effect on the temperature of the HTL / WF mixture. This quasi-isothermal expansion causes the HTL / WF mixture to accelerate, and the mixture is discharged through the one or more nozzles. The kinetic energy released by the nozzles is converted into work by inducing rotation in the turbine, while simultaneously reducing the temperature of the HTL. This work can be converted into electricity (generated in a generator rotationally coupled to the turbine), which can be stored or used immediately. The HTL / WF mixture discharged from the nozzles is received and may be received in an optional first separation zone configured to separate the WF from the HTL. The separated HTL can be recycled back to the thermal reservoir or one or more nozzles (these processes typically occur in parallel - a portion of the HTL is recycled back to the thermal reservoir, while some other hot HTL is pushed out of the reservoir in situ, and the other portion continues to circulate back to one or more nozzles). The separated WF can optionally be directed to flow through a first heat exchanger to reduce its temperature, and then be received in a condenser to be condensed in the condenser. The condensed WF flow discharged from the condenser can be driven by a pressurization arrangement configured to pressurize or propel WF, for example, such a pressurization arrangement includes a WF pump configured to pump WF back to the turbine under high pressure, typically through an optional first heat exchanger, at which the WF can be heated by the counterflow WF flowing from the turbine to the condenser (as described above, the counterflow WF is cooled when passing through the heat exchanger). The arrangement can also pressurize the WF to the turbine operating pressure. The arrangement can be arranged upstream of the first heat exchanger and downstream of the condenser. In some embodiments, the WF pump is integrated into the condenser.In some embodiments, the pumping arrangement consists of a turbine, ie the centrifugal force of the turbine causes the WF to be pumped back to the turbine at high pressure.

[0030] Here, the turbine may have a plurality of nozzles fixedly coupled to the turbine shaft so that the kinetic energy generated thereby causes the shaft to rotate. The nozzles may be provided on dedicated elements extending radially from the shaft, or may be provided on rotating blades of the turbine.

[0031] In the charging mode of operation, according to one embodiment of the first system aspect of the present disclosure, WF flows in a second flow path, and the compressor is configured to receive hot HTL and WF vapor from a hot HTL reservoir, for example, WF vapor passed through a second heat exchanger, to form an HTL / WF mixture. The WF in this mixture is compressed quasi-isothermally and optionally condensed along the compressor flow path (in the case of LVPhC). Typically, the WF and HTL are caused to flow together through a nozzle configured to allow quasi-isothermal compression, i.e., compression, wherein the WF is maintained at approximately the same temperature due to heat exchange with the HTL, which has a much larger heat capacity. In other words, the heating of the WF during the compression process has a negligible effect on the temperature of the HTL / MF mixture. The HTL / WF mixture can be separated in an optional second separation zone. The separated HTL is circulated back to the hot reservoir or the compressor (these typically occur in parallel—a portion of the HTL is recycled back to the hot reservoir, while some other hot HTL is pushed into the compressor, and the other portion continues to circulate within the compressor). Compressed WF is discharged from the compressor and, for example, flows through a second heat exchanger to reduce its temperature, flows to the evaporator to experience evaporation, optionally flash evaporation, and thus it is cooled to a cooling temperature lower than the ambient temperature. This cooling temperature is set by the inlet pressure of the compressor. Alternatively, only a portion of the WF is evaporated. After evaporation, the steam can be further heated by the environment to reach complete evaporation at the ambient temperature. The evaporated WF discharged from the evaporator can be directed to flow through an optional second heat exchanger to be heated by heat exchange with the countercurrent WF (as mentioned above, the countercurrent WF is cooled while passing through the heat exchanger) flowing from the compressor to the evaporator, and then return to the compressor to carry out another cycle. Alternatively, complete evaporation is reached only after the regenerator. The compressor can be operated by an electric motor coupled to it in terms of rotation, thereby storing the generated electrical energy in the power grid or allowing electrical energy to enter the power grid, for use later, for example, when peak power grid energy demand is used.

[0032] In some embodiments of the first system aspect, the discharging operation mode and the charging operation mode are both according to the above-described embodiments.

[0033] Thus, the system of the first system aspect is capable of switching between two operating modes: a discharge mode and a charge mode. In the discharge mode, hot tidal fluid (HTL) from a hot tidal fluid (HTL) reservoir circulates between the reservoir and the turbine, utilizing the heat stored in the hot tidal fluid (HTL) reservoir and transported by the HTL, thereby reducing the temperature of the HTL throughout the process. In the discharge mode, the thermally heated fluid (WF) flows through various elements in the following sequence (the starting point in the following description is arbitrary, as the WF is intentionally circulated during the process): it is received in the turbine; then flows through a first heat exchanger in one flow direction to the condenser; then returns from the condenser through the first heat exchanger in a flow direction opposite to the one flow direction, back to the turbine; this flow, particularly from the condenser to the turbine, is driven by a WF pump. In the charge mode, the thermally heated tidal fluid (HTL) from the hot tidal fluid (HTL) reservoir circulates between the reservoir and the compressor, or, if the compressor has its own compressor HTL, is thermally coupled to the compressor HTL, thereby increasing the temperature of the HTL with each cycle. In charging mode, the WF flows in a flow path through the following elements in the following order (here again, the starting point in the following description is arbitrary because the WF is intentionally circulated in the process): is received in the compressor; then flows in one direction through the second heat exchanger to the evaporator; and then returns from the evaporator to the compressor through the second heat exchanger in a flow direction opposite to the one flow direction.

[0034] A second system aspect of the present disclosure provides a system for storing heat and extracting electrical energy, the system comprising a two-phase turbine and a two-phase compressor. The system also includes a hot HTL reservoir containing hot HTL and a cold HTL reservoir containing cold HTL, each of the hot HTL reservoir and the cold HTL reservoir being selectively connectable to either a quasi-isothermal, adiabatic compressor / condenser or a quasi-isothermal, adiabatic turbine, depending on the operating mode of the system.

[0035] The two-phase compressor may include a compressor HTL for its compression operation and a compressor HTL reservoir for containing the compressor HTL. The compressor HTL may be identical to the hot HTL and the cold HTL, and the compressor HTL reservoir may be identical to the hot HTL reservoir and the cold HTL reservoir, so that in charging mode, the hot HTL reservoir is fluidically coupled to the compressor for supplying hot HTL to the compressor, and in discharging mode, the cold HTL reservoir is fluidically coupled to the compressor for supplying cold HTL to the compressor, or the compressor HTL and the compressor HTL reservoir may be distinct from the hot HTL and the hot HTL reservoir, respectively, and the compressor HTL flows in a flow path that allows the compressor HTL to thermally exchange heat with the hot HTL reservoir to heat the hot HTL reservoir in charging mode or to cool the cold HTL reservoir in discharging mode.

[0036] A hot HTL is defined by a higher temperature than a cold HTL. The hot HTL can be used: (i) in charging mode, to compress the WF mixed therein in the compressor, while being gradually heated in the compressor during the quasi-isothermal compression of the WF, resulting in a relatively gradual increase in the temperature of the heat reservoir; and (ii) in discharging mode, to operate the turbine, i.e., to participate in the isothermal expansion of the HTL / working fluid mixture, utilizing the heat stored in the heat reservoir that gradually decreases during this process. The cold HTL can be used: (i) in discharging mode, to condense and compress the WF in the compressor; and (ii) in charging mode, to participate in the isothermal expansion of the HTL / WF mixture, thereby heating it in the process. Therefore, the minimum temperature of the cold HTL must be higher than the boiling point of the working fluid at the initial pressure in the turbine. The hot HTL can be made of the same or different material as the cold HTL.

[0037] In the charging operating mode of the system of the second system aspect, heat flows from the cold reservoir to the hot reservoir via the WF medium, cooling the cold reservoir and heating the hot reservoir during this process, mediated by the input electrical energy of the compressor. In the discharging operating mode of the system, heat flows from the hot reservoir to the cold reservoir via the WF medium, cooling the hot reservoir and heating the cold reservoir during this process, and this energy flow is converted into electrical energy by the turbine.

[0038] The system of the second system aspect further includes an intermediate heat exchanger disposed in the flow path between the compressor and the turbine.

[0039] In a charging mode of operation of the system of the second system aspect, a compressor / condenser receives hot HTL from a hot HTL reservoir and quasi-isothermally compresses and quasi-isothermally condenses LVPhC WF mixed with the hot HTL, wherein the compressor / condenser is powered by an external energy source, typically an electric motor that receives energy from an external source, such as an access point from the grid during periods of low electricity demand or generated electricity that cannot be directed to the grid at the time of production. This compression gradually heats the hot HTL through the charging process. The HTL / WF mixture is separated, and the hot HTL is directed to an HTL reservoir or recycled for continued use in the compressor (as above, these typically occur in parallel—some portion of the HTL is recycled back to the hot reservoir, while some other hot HTL is pushed into the compressor, and some other portion continues to circulate within the compressor). The compressed and condensed WF discharged from the compressor / condenser flows through a first heat exchanger in one flow path to reduce its temperature, and then optionally mixes with cold HTL in one or more nozzles of a turbine to be evaporated and undergoes isothermal or quasi-isothermal expansion in one or more nozzles. This accelerates the HTL and evaporated WF mixture in a manner similar to that described above, generating kinetic energy. This kinetic energy can be converted into electrical energy by a generator rotationally coupled to the turbine, which can be used to provide auxiliary power to the compressor. Optionally, the cold liquid WF is partially flashed without a turbine and fully evaporated by extracting heat from the environment in an evaporator. The evaporated WF discharged from the turbine or evaporator is directed toward the first heat exchanger, flowing through it in a flow path opposite to the one flow path, thereby being heated (while the compressed and condensed WF is cooled in the process) and then received by the compressor for another cycle.

[0040] In the energy-discharging operating mode of the system of the second system aspect, the compressor (powered by a portion of the energy generated by the turbine, as described below) is optionally configured to receive cold HTL from a cold HTL reservoir and quasi-isothermally condense and compress the LVPhC WF mixed in the cold HTL. This compression gradually heats the cold HTL through the charging process. The HTL / WF mixture is separated, and the hot HTL is directed to the HTL reservoir or recycled for further use within the compressor (as described above, these typically occur in parallel—some portion of the HTL is recycled back to the hot reservoir, while some other hot HTL is pushed into the compressor, and some other portion continues to circulate within the compressor). Optionally, the WF is condensed in the condenser, causing the WF to condense. The condensed WF discharged from the compressor or condenser flows in a unidirectional flow path through a first heat exchanger, thereby increasing its temperature, and then flows to the turbine to mix with the hot HTL in the turbine nozzle, thereby evaporating and undergoing quasi-isothermal expansion, which accelerates the HTL and WF mixture to generate kinetic energy that can be converted into electricity. The WF discharged from the turbine is directed toward the first heat exchanger to flow in a flow path in the opposite direction to the unidirectional flow path, thereby being cooled (with the condensed WF being heated in the process) and then received in the compressor or condenser for another cycle.

[0041] It should be noted that in embodiments where the compressor has its own compressor HTL, the coupling of the compressor to the hot and cold HTL reservoirs is only thermal, and the hot and cold HTL do not participate in the compression process in the compressor. In this embodiment, the only HTL participating in the compression process is the compressor HTL, and the flow path of the compressor HTL is designed to exchange heat with the hot and cold HTL reservoirs in charging and discharging modes, respectively.

[0042] The system according to the third system aspect is similar in most of its elements to those of the second system aspect, the main difference being that the WF is a LVPhC WF.

[0043] The system for storing and extracting energy in respective charging and discharging operating modes of this third system aspect includes: a two-phase turbine and a two-phase compressor; a hot HTL reservoir containing hot HTL and a cold HTL reservoir containing cold HTL, each of the hot HTL reservoir and the cold HTL reservoir being selectively connectable to either the compressor / condenser or the turbine; and an intermediate exchanger disposed in the flow path between the compressor and the turbine. The two-phase compressor may include a compressor HTL for its compression operation and a compressor HTL reservoir for containing the compressor HTL. The compressor HTL can be the same as the hot HTL and the cold HTL, and the compressor HTL reservoir can be the same as the hot HTL reservoir and the cold HTL reservoir, and then in the charging mode, the hot HTL reservoir fluid is connected to the compressor for supplying hot HTL to the compressor, and in the discharging mode, the cold HTL reservoir fluid is connected to the compressor for supplying cold HTL to the compressor, or the compressor HTL and the compressor HTL reservoir can be different from the hot HTL and the hot HTL reservoir, respectively, and the compressor HTL flows in a flow path, which allows the compressor HTL to thermally exchange heat with the hot HTL reservoir to heat the hot HTL reservoir in the charging mode or to cool the cold HTL reservoir in the discharging mode.

[0044] In charging mode, the compressor / condenser is fluidically connected to a hot HTL reservoir configured to receive hot HTL from the compressor / condenser and quasi-isothermally compress and quasi-isothermally condense WF, which is a liquid / vapor phase-change working fluid (LVPhC) mixed with the hot HTL. The condensed LVPhC flows through a first heat exchanger to reduce its temperature and then mixes with cold HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and evaporated LVPhC mixture to generate kinetic energy that can be converted into electricity. The evaporated LVPhC discharged from the turbine is directed toward an intermediate heat exchanger to be heated for another cycle.

[0045] In the discharge mode, the compressor is configured to receive cold HTL from the cold HTL reservoir and quasi-isothermally condense and compress the LVPhC mixed in the cold HTL. This condensed LVPhC flows through an intermediate heat exchanger to increase its temperature before mixing with the hot HTL in one or more turbine nozzles. In the nozzles, the mixture evaporates and undergoes quasi-isothermal expansion, which accelerates the HTL and LVPhC mixture to generate kinetic energy that can be converted into electricity. The LVPhC discharged from the turbine is directed toward the first heat exchanger to be cooled, completing another cycle.

[0046] It should be noted that in embodiments where the compressor has its own compressor HTL, the coupling of the compressor to the hot and cold HTL reservoirs is only thermal, and the hot and cold HTL do not participate in the compression process in the compressor. In this embodiment, the only HTL participating in the compression process is the compressor HTL, and the flow path of the compressor HTL is designed to exchange heat with the hot and cold HTL reservoirs in charging and discharging modes, respectively.

[0047] Some embodiments of the present disclosure will now be described. It should be noted that any combination of the following embodiments of any system aspect of the present disclosure is applicable. In other words, any system aspect of the present disclosure can be defined by any combination of the described embodiments. Unless otherwise specified, the term "system" will be used below to collectively refer to the systems of the first system aspect, the second system aspect, and the third system aspect.

[0048] In some embodiments of the system, the evaporator and condenser are the same element. That is, the evaporator / condenser is an element configured to exchange heat with its surroundings, and the heat exchange is based on the relationship between the temperature and pressure of the WF and the surroundings of the evaporator / condenser, resulting in either evaporation of the WF or condensation of the WF. In some embodiments, a partial flash evaporation of the liquid WF is performed in the evaporator prior to complete evaporation.

[0049] In some embodiments of the system, a single heat exchanger is present in the system for operation in both the charging and discharging modes of the system. For example, in the system of the first system aspect, the first countercurrent heat exchanger and the second countercurrent heat exchanger are the same heat exchanger element. In the system of the first system aspect, a single heat exchanger is selectively connectable to the turbine or compressor in the respective discharging or charging operating modes. However, two different heat exchanger elements may also be used, for example, one heat exchanger element optimally configured for use in the discharging operating mode and another heat exchanger element optimally configured for use in the charging operating mode.

[0050] In some embodiments, the system further comprises at least one pressure reducing nozzle disposed in the second flow path between the second heat exchanger and the evaporator (and operating during charging) to reduce the pressure and temperature of the WF flowing from the second heat exchanger to the evaporator, and thereby achieve a greater temperature difference between the surrounding environment of the evaporator and the WF in the evaporator to increase heat transfer relative to the surrounding environment. It is noted that in embodiments in which (1) there is a common heat exchanger, (2) the evaporator and the condenser are the same element, or (3) both (1) and (2), the pressure reducing nozzle is selectively coupled to the second heat exchanger and the evaporator only in charging mode and is disconnected in discharging mode.

[0051] In some embodiments of the system, the pressure relief nozzle is an orifice.

[0052] In some embodiments, the pressure reduction nozzle is a flash nozzle that partially vaporizes the WF and cools the WF temperature to below the ambient temperature.

[0053] In some embodiments of the system, the WF is a liquid / vapor phase change (LVPhC) WF that is selected to be: (i) in vapor phase upon (1) entering the compressor, (2) at temperature equilibrium after mixing with the HTL in the turbine, and (3) upon leaving the evaporator; and (ii) in liquid phase upon (4) leaving the condenser and (5) leaving the compressor.

[0054] In some embodiments of the system, one or both of the compressor and the turbine are thermally insulated.

[0055] In some embodiments, the system further comprises one or more selector valves that enable selective connection of the hot HTL reservoir to the compressor or the turbine.

[0056] In some embodiments, the system further comprises one or more selector valves that enable the hot HTL reservoir to be selectively connected to the compressor or turbine in respective charging and discharging modes; and that enable the cold HTL reservoir to be selectively connected to the compressor or turbine in respective discharging and charging modes.

[0057] In some embodiments of the system, the HTL is selected from the list consisting of: antifreeze liquid, water, brine, hot oil, molten salt, ethylene glycol, and WF in liquid phase.

[0058] In some embodiments of the system, the WF is selected from the list consisting of the following: air, nitrogen, hydrogen, CO2, ammonia, propane, ORC phase change material, pentane, cyclopentane, refrigeration phase change material. In some embodiments, the compressor HTL is the same material as the WF. Optionally, when the compressor HTL is different from the hot HTL and flows in a closed loop in the compressor, the compressor HTL and the WF are the same material. In order to heat the hot HTL reservoir, the compressor HTL flows along a flow path having a portion that allows heat exchange with the hot HTL reservoir for transferring heat from the compressor HTL to the hot HTL reservoir and therefore to the hot HTL.

[0059] In some embodiments, the system also includes an external heat source, such as from waste energy, gas, or combustion of fossil fuels, to allow for controlled heating of the HTL. This may be the case, for example, if the system is intended to function as a standard heat engine, and the external heat source can be used to heat the HTL during energy production, such as by heating an evaporator or applying heat via a dedicated heating zone in the HTL flow path. This arrangement can be used when the thermal energy in the system is depleted.

[0060] According to some embodiments of the present disclosure, external heat is used to heat the WF in the evaporator to improve evaporation or to raise the evaporated WF to a temperature higher than the ambient temperature, and optionally ultimately to a pressure higher than the ambient pressure, thereby saving compressor power consumption. Optionally, the heat source used to heat the evaporator is a waste heat source.

[0061] In some embodiments of the system, the external heat source is provided by burning gas or fossil fuels that directly heat the HTL.

[0062] In some embodiments, the system further comprises an external heat source that allows for controllable heating of the thermal reservoir.

[0063] In some embodiments of the system, the condenser and the evaporator are configured to exchange heat with the surrounding environment to perform condensation and evaporation, respectively.

[0064] In some embodiments of the system, the evaporator is configured to be heated by an external heat source, such as waste heat, during the charging mode of operation. The external heat source can be used to evaporate the working fluid and bring it to a desired temperature, which can improve system efficiency. When the condenser and evaporator are the same component, the external heat source is thermally coupled only to the condenser / evaporator during the charging mode.

[0065] In some embodiments, the system further comprises an insulated enclosure comprising the condenser and the evaporator, wherein the enclosure generally allows for controlled heat exchange with the surrounding environment. To this end, the enclosure may include an inlet for receiving heat from an external heat source, such as in the form of exhaust gases or waste heat, and an outlet for controlled release of excess heat, allowing circulation of incoming and outgoing heat within the enclosure.

[0066] In some embodiments of the system, the external heat source is waste heat. The waste heat can be at any temperature above ambient temperature.

[0067] In some embodiments of the system, the heat exchangers, including the first and second counter-flow heat exchangers of the first system aspect and the intermediate heat exchangers of the second and third aspects, are regenerators.

[0068] In some embodiments of the system, the system is configured such that the WF pressure at the inlet of the compressor and the WF pressure in the evaporator are approximately the same and below the critical pressure of the critical point at a temperature lower than the ambient temperature, thereby allowing the WF to evaporate and allowing heat to flow from the ambient to the WF vapor.

[0069] In some embodiments of the system, the first heat exchanger includes a first thermal pendulum.

[0070] In some embodiments of the system, the heat exchanger (including the first heat exchanger or the second heat exchanger in the first system aspect and the intermediate heat exchangers in the second system aspect and the third system aspect) includes a first heat exchanger section, a second heat exchanger section and a first thermal pendulum section; wherein the flow path of WF between the first heat exchanger section and the second heat exchanger section passes through the thermal pendulum.

[0071] In some embodiments of the system, the heat pendulum is designed to exchange heat only with the liquid phase WF flowing in the first heat exchanger.

[0072] In some embodiments of the system, the flow path of the WF is such that it flows continuously in different operating modes, either flowing from the first heat exchanger section to the hot pendulum and then to the second heat exchanger section, or from the second heat exchanger section to the hot pendulum and then to the first heat exchanger section.

[0073] When the system comprises more than one heat exchanger, the thermal pendulum, when present, and the overall design of the exchangers may be the same or different in all heat exchangers.

[0074] In some embodiments of the system, the heat capacity of the heat pendulum is greater than the heat capacity of the WF in its liquid phase, and the heat pendulum is configured to exchange heat with the WF passing through the heat pendulum, i.e., the working fluid discharged from the first heat exchanger or the second heat exchanger, to compensate for the inefficient heat exchange between the liquid phase of the WF and the gas phase of the WF, so that (1) in the charging operation mode, the heat pendulum is heated while cooling the liquid before the liquid enters the turbine, and (2) in the discharging operation mode, the heat pendulum is cooled while heating the liquid before the liquid enters the turbine.

[0075] In some embodiments of the system, the flow path of the WF is a closed-loop flow path, ie, the WF flows in a closed system and is recirculated in each thermodynamic cycle of the system.

[0076] In some embodiments of the system, the turbine includes one or more nozzles and is configured to increase the pressure of the HTL received in the turbine to obtain high-pressure HTL, i.e., a pressure higher than ambient or higher than the pressure of the HTL in the HTL thermal reservoir, and introduce the high-pressure HTL into the one or more nozzles to mix with the WF at approximately the same pressure in the one or more nozzles, thereby forming an HTL / WF mixture. This allows the WF to expand quasi-isothermally within the one or more nozzles, causing the HTL / WF mixture to accelerate toward the nozzle outlet, and the kinetic energy of the HTL / WF mixture ejected from the outlet is used to generate energy.

[0077] The turbine may be a reaction turbine or an impulse turbine.

[0078] In some embodiments of the system, the turbine includes an HTL pump configured to pressurize the HTL received in the turbine prior to introducing the HTL into a nozzle of the turbine.

[0079] In some embodiments of the system, the turbine is a reaction turbine.

[0080] In some embodiments of the system, the first separation zone includes a collection unit that collects the injected HTL separated from the WF and allows the injected HTL to be directed to a hot HTL reservoir or returned to the turbine nozzle. For example, a portion of the HTL can be directed to the HTL reservoir, and a portion of the HTL can be directed back to the nozzle or HTL pump.

[0081] In some embodiments of the system, the turbine is a reaction turbine, and the one or more nozzles are coupled to, mounted on, or are part of the reaction turbine.

[0082] In some embodiments, the collection unit defines a discharge section in which separated HTL accumulates. The HTL is drawn from the discharge section into the nozzle by the centrifugal force acting on the liquid in the nozzle, induced by the reaction turbine. This centrifugal force provides the driving force for the entire HTL column, ultimately leading to this aspiration. To ensure unimpeded aspiration, some HTL must always remain in the HTL discharge section. This centrifugal force acts as an HTL pump. This propulsion of the HTL from the discharge section allows the HTL to enter the nozzle at the nozzle's operating pressure, thereby achieving the desired isothermal expansion.

[0083] In some embodiments of the system, the first separation zone comprises a curved or circular frame onto which the mixture is sprayed, engagement of the mixture with the curved or circular frame resulting in film-like flow on a surface of the curved or circular frame.

[0084] In some embodiments of the system, the compressor includes an HTL pump configured to increase the pressure of the HTL, the HTL pump being fluidly coupled to a compressor nozzle, the compressor nozzle being configured to receive pressurized HTL from the HTL pump and mix the pressurized HTL with WF to obtain an HTL / WF mixture within the nozzle, wherein the nozzle is designed to discharge the HTL / WF at a higher pressure than the pressure of the WF introduced into the compressor.

[0085] In some embodiments of the system, the condenser comprises the WF pump.

[0086] In some embodiments of the system, the compressor HTL is distinct from the hot HTL and flows in a closed-loop manner within the compressor and, in charging mode, exchanges heat with a hot HTL reservoir. In other words, the compressor has its own compressor HTL that flows in a closed-loop manner. The HTL is heated during the compression cycle and flows as part of its closed-loop flow path, exchanging heat with the hot HTL reservoir to heat the hot HTL reservoir, which contains the hot HTL used by the turbine.

[0087] In some embodiments of the system, the compressor HTL is the same as the hot HTL, and in charging mode, the hot HTL reservoir is fluidly connectable to at least one two-phase compressor for supplying hot HTL to the at least one compressor. That is, in charging mode, the hot HTL reservoir is fluidly connected to the compressor, and hot HTL flows between the compressor and the hot HTL reservoir.

[0088] In some embodiments, the system further comprises at least one pressurizing arrangement configured to pressurize or advance the WF after the WF is condensed in the at least one condenser.

[0089] In some embodiments of the system, the pressurizing arrangement comprises a pump.

[0090] In some embodiments of the system, the pressurizing arrangement is included within a turbine.

[0091] In some embodiments of the system, the pressurizing arrangement is constituted by a turbine, ie the rotation of the turbine and its centrifugal force causes the WF to be pumped into the turbine at a high operating pressure in the turbine before isothermal expansion.

[0092] The following is a description of some exemplary embodiments of the compressor or compressor / condenser of the system of the present disclosure. Note that any of the following definitions may be applied and used in any combination in the system of the present disclosure.

[0093] The compressor elements will be described with reference to the flow of compressed fluid in a downstream flow direction. The terms "proximal" and "distal" will be used to refer to respective relative positions upstream or downstream relative to a reference position. In other words, the proximal position is the position through which the fluid flows before reaching the more distal position.

[0094] The compressor can include a compressor pump, one or more WF introduction orifices, and a fluid manipulation zone, wherein the compressor pump is configured to pump the HTL in a closed loop filled with the HTL, the fluid manipulation zone being arranged between a proximal suction inlet and a distal outlet. The fluid manipulation section includes four sections, including a first fluid manipulation zone having a configuration in which its walls narrow or converge between a wide proximal end and a narrower distal end. The purpose is to accelerate the flow of the HTL and reduce the static pressure of the HTL so that it has a lower pressure when entering the second section. The second section is a fluid mixing section having a converging configuration between a narrow proximal end (which is also the distal end of the first section) and a wider distal end.

[0095] The WF introduction orifice may be one or more specialized nozzles configured to introduce WF into an orifice defined in the second section or a wall of the section. The orifice is configured to introduce WF into the zone where it mixes with the HTL to form an HTL / WF mixture. At this stage, the speed of sound decreases and the mixture velocity becomes supersonic.

[0096] The third section of the fluid manipulation zone has a narrowing configuration between its proximal end and its distal end, and is configured to decelerate the supersonic flow of the HTL / WF mixture to a sonic or subsonic velocity and to increase the pressure of the two-phase mixture flowing along the third fluid manipulation section. The fourth fluid manipulation section has a widening configuration between its proximal and distal ends, and is configured to decelerate the subsonic flow of the HTL / WF mixture received from the third fluid manipulation section and to increase the static pressure of the subsonic flow of the HTL / WF mixture to the pressure existing at the outlet of the manipulation zone.

[0097] In some embodiments, the WF is a vapor that is condensed with quasi-isothermal compression, and the fluid mixture discharged from the outlet is a liquid mixture with pressurized or condensed WF in the HTL / WF mixture. That is, the WF can be drawn into the maneuvering zone in the vapor phase, and during flow in each segment, the WF changes phase to a liquid state and is discharged at the proximal outlet end.

[0098] In some embodiments of the manipulation zone, the pressure value of the HTL at the distal outlet of the fourth segment is 2 bar, 1 bar, 0.5 bar, 0.3 bar or 0.1 bar lower than the initial pressure value of the HTL flowing into the proximal inlet of the first segment.

[0099] In some embodiments, the initial pressure value is up to 30% greater than the outlet pressure.

[0100] In some embodiments of the manipulation zone, the intake fluid flowing into the first fluid manipulation section has a subsonic velocity.

[0101] In some embodiments of the steering zone, the steering zone inlet is configured to be in fluid communication with a source of HTL for receiving the HTL at a pressure greater than ambient pressure.

[0102] In some embodiments of the compressor, a separation zone is provided, the separation zone being configured to receive the fluid mixture discharged from the manipulation zone outlet and separate the HTL and pressurized WF, wherein the separated pressurized WF is directed to the fluid outlet to be discharged therethrough.

[0103] In some embodiments of the compressor, the pressurized HTL / WF mixture is discharged from the proximal fluid outlet at the same flow rate as the HTL introduced into the proximal inlet.

[0104] In some embodiments of the compressor, the compressor pump unit is configured to receive fluid from the separation region.

[0105] In some embodiments of the compressor, the compressor pump is a centrifugal pump, such as a vertical fluid pump.

[0106] In some embodiments of the compressor, the centrifugal pump has a fluid inlet, e.g. a bottom inlet in the case of a vertical centrifugal pump, configured for enabling liquid to flow through the fluid inlet, wherein the liquid inlet is in fluid communication with a liquid discharge of the separation zone storing the separated liquid.

[0107] In some embodiments of the compressor, the centrifugal pump has at least one arm for supporting fluid flow therethrough and is fluidly coupled to the at least one nozzle.

[0108] In some embodiments of the compressor, a vertical centrifugal pump is rotatable about its vertical axis so as to suck the HTL through the bottom fluid inlet.

[0109] In some embodiments of the compressor, the HTL flows along a fluid flow path in the system, wherein the fluid flow path includes at least one closed-loop flow path, i.e., the separated liquid in the separation zone is pumped back to the manipulation zone, and wherein the pump unit is configured to receive the fluid from the separation zone and pressurize the fluid from the separation zone to obtain pressurized HTL and flow the pressurized HTL into the manipulation zone.

[0110] In some embodiments of the compressor, the HTL is separated from the two-phase mixture in the separation zone by gravity.

[0111] In some embodiments of the compressor, the separation zone includes a curved or circular frame, onto which the two-phase mixture is sprayed from a nozzle, and the engagement of the mixture with the curved or circular frame causes a film flow on the surface of the curved or circular frame, thereby separating the gas from the liquid.

[0112] In some embodiments of the compressor, the fluid outlet includes a pressure regulating valve configured to controllably flow the compressed HTL through the fluid outlet when (i) a positive pressure differential exists between the compressed fluid and a fluid tank that is fluidically coupled to the fluid outlet or (ii) the positive pressure differential exceeds a pressure threshold of the compressed fluid.

[0113] The present invention also provides a system for converting electrical energy into heat and extracting stored heat into electrical energy, the system comprising: (i) a system according to the first system aspect, the second system aspect or the third system aspect; (ii) at least one generator, the at least one generator being rotationally coupled to at least one turbine for generating electricity in an energy release operating mode; and (iii) at least one electric motor, the at least one electric motor being rotationally coupled to at least one compressor for operating the compressor to charge heat to at least one heat reservoir.

[0114] Implementation Method

[0115] The following numbered paragraphs (written in a format similar to the claims for convenience) define some optional embodiments according to various aspects of the present disclosure, including multiple independent embodiments and multiple dependent embodiments (i.e., embodiments that relate to another embodiment, such as "a system according to any of embodiments 1 to 33..."). These embodiments can be applied by themselves and can also be any suitable combination thereof. These embodiments are intended to supplement the above general description and do not limit the above general description in any way. If a dependent embodiment is dependent on another embodiment (referred to as the "reference embodiment" in this paragraph) and includes certain elements represented by the qualifier "the" (e.g., "the second flow path"), it is assumed that with respect to such dependent embodiment (and only such dependent embodiment), the qualifying element is present in the reference embodiment, even if such element is not defined in the reference embodiment; such element in the reference embodiment is optionally one of such elements referenced in other embodiments or in the above description.

[0116] 1. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0117] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0118] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0119] wherein at least one hot HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the hot HTL when they are different, or supplying the hot HTL to the at least one compressor when the compressor HTL and the hot HTL are the same in the charge mode (note that the hot HTL and the compressor HTL may be different, i.e., they are not mixed with each other, but may be the same material);

[0120] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0121] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0122] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0123] wherein, in the energy release mode, WF flows in a first flow path from at least one condenser to one or more nozzles within the at least one turbine, the nozzle being configured to cause rotation of the turbine when the fluid is discharged from the nozzle, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one heat storage or the one or more nozzles, and the separated WF flowing into the condenser and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine.

[0124] 2. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0125] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0126] at least one two-phase turbine and at least one two-phase compressor;

[0127] wherein at least one hot HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidly connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying hot HTL to the corresponding turbine in the discharge mode or for (2) supplying hot HTL to the compressor in the charge mode;

[0128] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0129] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0130] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0131] wherein, in the energy release mode, WF flows in a first flow path from at least one condenser to one or more nozzles within the at least one turbine, the nozzle being configured to cause rotation of the turbine when the fluid is discharged from the nozzle, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one heat storage or the one or more nozzles, and the separated WF flowing into the condenser and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine.

[0132] 3. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0133] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0134] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0135] wherein at least one thermal HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) thermally connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying thermal HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the HTL of the thermal reservoir in the charge mode;

[0136] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0137] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0138] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0139] wherein, in the energy release mode, WF flows in a first flow path from at least one condenser to one or more nozzles within the at least one turbine, the nozzle being configured to cause rotation of the turbine when the fluid is discharged from the nozzle, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one heat storage or the one or more nozzles, and the separated WF flowing into the condenser and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine.

[0140] 4. The system according to any one of embodiments 1 to 3, comprising at least one first counter-flow heat exchanger, which is arranged in the first flow path between at least one turbine and at least one condenser and is configured to perform heat exchange between WF leaving from the at least one turbine and WF leaving from the at least one condenser.

[0141] 5. The system of embodiment 4, wherein the heat exchanger is configured to reduce the temperature of WF flowing from the turbine to the condenser.

[0142] 6. The system according to any one of embodiments 1 to 5, comprising at least one pressurizing arrangement configured to pressurize or propel the WF after the WF is condensed in the at least one condenser.

[0143] 7. The system of embodiment 6, wherein the arrangement comprises a pump.

[0144] 8. The system according to any one of embodiments 1 to 7, comprising at least one first separation zone disposed in at least one turbine, the at least one first separation zone being configured to separate between the WF and the HTL.

[0145] 9. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0146] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0147] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0148] wherein at least one hot HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the hot HTL when they are different, or supplying the hot HTL to the at least one compressor when the compressor HTL and the hot HTL are the same in the charge mode (note that the hot HTL and the compressor HTL may be different, i.e., they are not mixed with each other, but may be the same material);

[0149] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0150] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0151] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0152] Wherein, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to form a compressor HTL / WF mixture and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the compressor HTL, and the compressor HTL exchanges heat with the hot HTL reservoir, thereby heating the hot HTL reservoir and circulating back to the same or different reservoir as the hot HTL reservoir or at least one compressor, and the compressed WF discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator is directed back to the at least one compressor.

[0153] 10. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0154] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0155] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0156] wherein at least one thermal HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) thermally connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying thermal HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the HTL of the thermal reservoir in the charge mode;

[0157] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0158] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0159] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0160] In which, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to form a compressor HTL / WF mixture and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the compressor HTL, and the compressor HTL exchanges heat with a hot HTL reservoir, thereby heating the hot HTL reservoir and circulating back to a reservoir or compressor that is the same as or different from the hot HTL reservoir, and the compressed WF discharged from the at least one compressor flows to be received in an evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator is directed back to the at least one compressor.

[0161] 11. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0162] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0163] at least one two-phase turbine and at least one two-phase compressor;

[0164] wherein at least one hot HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidly connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying hot HTL to the corresponding turbine in the discharge mode or for (2) supplying hot HTL to the at least one compressor;

[0165] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0166] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0167] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0168] In which, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to receive WF and hot HTL to obtain an HTL / WF mixture, and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the hot HTL, the compressor HTL exchanges heat with the hot HTL reservoir, thereby heating the hot HTL reservoir and circulating back to the hot HTL reservoir or the compressor, the compressed WF discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator is guided back to the at least one compressor.

[0169] 12. The system of any one of embodiments 9 to 11, comprising at least one second counter-flow heat exchanger disposed in the second flow path between at least one compressor and at least one evaporator and configured for exchanging heat between WF exiting from at least one compressor and WF exiting from at least one evaporator.

[0170] 13. The system of embodiment 12, wherein the heat exchanger is configured to increase the temperature of the WF flowing from the compressor to the turbine.

[0171] 14. The system according to any one of embodiments 9 to 13, comprising at least one second separation zone disposed in at least one turbine, the at least one second separation zone being configured to separate between the HTL and the WF.

[0172] 15. The system according to any one of embodiments 9 to 14 comprises at least one pressure reducing nozzle, wherein the at least one pressure reducing nozzle is arranged between the at least one second heat exchanger and the at least one evaporator in the second flow path to reduce the pressure and temperature of the WF flowing from the at least one second heat exchanger to the at least one evaporator.

[0173] 16. A system according to any one of embodiments 1 to 15, wherein the WF is a liquid / vapor phase change (LVPhC) WF, which is selected to: (i) be in vapor phase when (1) entering at least one compressor, (2) after mixing with the HTL in at least one turbine, and (3) leaving at least one evaporator; and (ii) be in liquid phase when (4) leaving at least one condenser and (5) leaving at least one compressor.

[0174] 17. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0175] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0176] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0177] wherein at least one hot HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the hot HTL when they are different, or supplying the hot HTL to the at least one compressor when the compressor HTL and the hot HTL are the same in the charge mode (note that the hot HTL and the compressor HTL may be different, i.e., they are not mixed with each other, but may be the same material);

[0178] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0179] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0180] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0181] wherein, in the energy release mode, WF flows in a first flow path from at least one first condenser to one or more nozzles within the at least one turbine, the nozzles being configured to cause rotation of the turbine when the fluid is discharged from the nozzles, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one thermal reservoir or the one or more nozzles, and the separated WF flowing into and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine; and

[0182] Wherein, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to form a compressor HTL / WF mixture and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the compressor HTL, and the compressor HTL is circulated back to the same or different reservoir as the hot HTL reservoir or at least one compressor, and the compressed WF discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator returns to the at least one compressor.

[0183] 18. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0184] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0185] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor HTL which is the same as or different from the thermal HTL of the thermal reservoir;

[0186] wherein at least one thermal HTL reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) thermally connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying thermal HTL to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor HTL and the HTL of the thermal reservoir in the charge mode;

[0187] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0188] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0189] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0190] wherein, in the energy release mode, WF flows in a first flow path from at least one first condenser to one or more nozzles within the at least one turbine, the nozzles being configured to cause rotation of the turbine when the fluid is discharged from the nozzles, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one thermal reservoir or the one or more nozzles, and the separated WF flowing into and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine; and

[0191] Wherein, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to form a compressor HTL / WF mixture and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the compressor HTL, and the compressor HTL is circulated back to the reservoir or at least one compressor, and the compressed WF discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator returns to the at least one compressor.

[0192] 19. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising:

[0193] at least one hot heat transfer fluid (HTL) reservoir containing the hot HTL;

[0194] at least one two-phase turbine and at least one two-phase compressor;

[0195] wherein at least one hot HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidly connectable to the at least one two-phase compressor in a charge operating mode for (1) supplying hot HTL to the corresponding turbine in the discharge mode or for (2) supplying hot HTL to the at least one compressor;

[0196] at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid;

[0197] at least one evaporator, the at least one evaporator being in fluid communication with the at least one compressor for receiving WF from the at least one compressor and evaporating the WF, the at least one evaporator being the same or a different element from the at least one condenser;

[0198] The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; and

[0199] wherein, in the energy release mode, WF flows in a first flow path from at least one first condenser to one or more nozzles within the at least one turbine, the nozzles being configured to cause rotation of the turbine when the fluid is discharged from the nozzles, thereby mixing the WF with the HTL to form an HTL / WF mixture in the one or more nozzles, in which the WF undergoes quasi-isothermal expansion, thereby accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles while reducing the temperature of the HTL, the HTL / WF mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the WF from the HTL, the HTL being recycled back to the at least one thermal reservoir or the one or more nozzles, and the separated WF flowing into and being received in the condenser to undergo condensation in the condenser, the condensed WF discharged from the at least one condenser flowing back to the turbine; and

[0200] wherein, in the charging mode, WF flows in the second flow path, and at least one compressor is configured to receive hot HTL and WF to obtain an HTL / WF mixture, and quasi-isothermally compress the WF in the mixture along the compressor flow path, thereby heating the hot HTL, the HTL circulates back to the hot HTL reservoir or the at least one compressor, and the compressed WF discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated WF discharged from the at least one evaporator flows back to the at least one compressor.

[0201] 20. A system for storing and extracting energy in respective charging and discharging modes, the system comprising:

[0202] at least one two-phase turbine and at least one two-phase compressor;

[0203] at least one hot HTL reservoir containing hot HTL and at least one cold HTL reservoir containing cold HTL, the at least one hot HTL reservoir and the at least one cold HTL reservoir each being selectively fluidly connectable to at least one compressor or at least one turbine;

[0204] at least one intermediate heat exchanger disposed in a flow path between the at least one compressor and the at least one turbine;

[0205] wherein, in a charging mode, at least one compressor is fluidly connected to at least one hot HTL reservoir to receive hot HTL from the at least one hot HTL reservoir, and the at least one compressor quasi-isothermally compresses a working fluid (WF) mixed with the hot HTL, such that the compressed working fluid flows through at least one first heat exchanger to reduce its temperature and then mixes with the cold HTL in one or more nozzles of the turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the turbine is directed toward the at least one first heat exchanger to be heated for use in another cycle;

[0206] Wherein, in the energy release mode, at least one compressor is configured to receive cold HTL from a cold HTL reservoir and quasi-isothermally compress the working fluid mixed in the cold HTL, so that the compressed working fluid flows through at least one first heat exchanger to increase its temperature, and then mixes with the hot HTL in one or more nozzles of the turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the HTL / WF mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for use in another cycle.

[0207] 21. A system for storing and extracting energy in respective charging and discharging modes, the system comprising:

[0208] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress the compressor HTL;

[0209] at least one hot HTL reservoir containing hot HTL and at least one cold HTL reservoir containing cold HTL, the at least one hot HTL reservoir and the at least one cold HTL reservoir each being selectively connectable to at least one compressor or at least one turbine and selectively thermally coupled to the at least one compressor or at least one turbine;

[0210] at least one intermediate heat exchanger disposed in a flow path between the at least one compressor and the at least one turbine;

[0211] wherein, in a charging mode, at least one compressor is configured to mix a working fluid (WF) with a compressor HTL to form a compressor HTL / WF mixture and quasi-isothermally compress the compressor HTL / WF mixture, thereby heating the compressor HTL, thermally coupling the compressor to at least one hot HTL reservoir to exchange heat between the compressor HTL and the hot HTL reservoir, the compressed WF flows through at least one first heat exchanger to reduce its temperature, and then mixes with the cold HTL in one or more nozzles of the turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the turbine is directed toward the at least one first heat exchanger to be heated for use in another cycle;

[0212] wherein, in the energy release mode, at least one compressor is configured to mix WF with the compressor HTL to form a compressor HTL / WF mixture, and quasi-isothermally compress the compressor HTL / WF mixture, thereby heating the compressor HTL, thermally coupling the compressor to at least one cold HTL reservoir to exchange heat between the compressor HTL and the cold HTL reservoir, the compressed working fluid flows through at least one first heat exchanger to increase its temperature, and then mixes with the hot HTL in one or more nozzles of the turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the HTL / WF mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for another cycle.

[0213] 22. A system for storing and extracting energy in respective charging and discharging modes, the system comprising:

[0214] at least one two-phase turbine and at least one two-phase compressor;

[0215] at least one hot HTL reservoir containing hot HTL and at least one cold HTL reservoir containing cold HTL, each of the at least one hot HTL reservoir and the at least one cold HTL reservoir being selectively connectable to at least one compressor / condenser or at least one turbine;

[0216] at least one intermediate heat exchanger disposed in a flow path between the at least one compressor and the at least one turbine;

[0217] wherein, in a charging mode, at least one compressor / condenser is fluidly connected to at least one hot HTL reservoir to receive hot HTL from the at least one hot HTL reservoir, and quasi-isothermally compresses and quasi-isothermally condenses a working fluid in a liquid / vapor phase change working fluid (LVPhC) mixed with the hot HTL, such that the condensed LVPhC flows through at least one first heat exchanger to reduce its temperature, and then mixes with the cold HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and evaporated LVPhC mixture to generate kinetic energy that can be converted into electrical energy, and the evaporated LVPhC discharged from the turbine is directed toward the at least one first heat exchanger to be heated for use in another cycle;

[0218] wherein, in the energy release mode, at least one compressor is configured to receive cold HTL from a cold HTL reservoir, and quasi-isothermally condense and quasi-isothermally compress the LVPhC mixed in the cold HTL, so that the condensed LVPhC flows through at least one first heat exchanger to increase its temperature, and then mixes with the hot HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and LVPhC mixture to generate kinetic energy that can be converted into electrical energy, and the LVPhC discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for use in another cycle.

[0219] 23. A system for storing and extracting energy in respective charging and discharging modes, the system comprising:

[0220] at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress the compressor HTL;

[0221] at least one hot HTL reservoir containing hot HTL and at least one cold HTL reservoir containing cold HTL, the at least one hot HTL reservoir and the at least one cold HTL reservoir each being selectively connectable to at least one compressor or at least one turbine and selectively thermally coupled to the at least one compressor or at least one turbine;

[0222] at least one intermediate heat exchanger disposed in a flow path between the at least one compressor and the at least one turbine;

[0223] wherein, in a charging mode, at least one compressor / condenser is thermally coupled to at least one hot HTL reservoir to exchange heat with the hot HTL reservoir, the at least one compressor / condenser being configured to mix a liquid / vapor phase change (LVPhC) working fluid (WF) with a compressor HTL to form a compressor HTL / WF mixture, and quasi-isothermally compress the compressor HTL / WF mixture and condense the compressor HTL / WF mixture, thereby heating the compressor HTL, the condensed LVPhC flowing through at least one first heat exchanger to reduce its temperature, and then mixing with the cold HTL in one or more nozzles of a turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and evaporated LVPhC mixture to generate kinetic energy that can be converted into electrical energy, and the evaporated LVPhC discharged from the turbine is directed toward at least the first heat exchanger to be heated for use in another cycle;

[0224] wherein, in an energy release mode, at least one compressor / condenser is thermally coupled to at least one cold HTL reservoir to exchange heat with the cold HTL reservoir, the at least one compressor / condenser is configured to mix WF with the compressor HTL to form a compressor HTL / WF mixture, and quasi-isothermally compress the compressor HTL / WF mixture and condense the compressor HTL / WF mixture, the condensed LVPhC flows through at least one first heat exchanger to increase its temperature, and then mixes with the hot HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the HTL and LVPhC mixture to generate kinetic energy that can be converted into electrical energy, and the LVPhC discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for use in another cycle.

[0225] 24. The system of any one of embodiments 1 to 23, wherein at least one evaporator and at least one condenser are the same element.

[0226] 25. The system of any one of embodiments 1 to 24, comprising at least one first counter-flow heat exchanger disposed in a first flow path between at least one turbine and at least one condenser and configured for exchanging heat between WF exiting from at least one turbine and WF exiting from at least one condenser.

[0227] 26. The system of embodiment 25, wherein the heat exchanger is configured to reduce the temperature of WF flowing from the turbine to the condenser.

[0228] 27. The system of any one of embodiments 1 to 26, comprising at least one second counter-flow heat exchanger disposed in the second flow path between at least one compressor and at least one evaporator and configured for exchanging heat between WF exiting from at least one compressor and WF exiting from at least one evaporator.

[0229] 28. The system of embodiment 27, wherein the heat exchanger is configured to increase the temperature of the WF flowing from the compressor to the turbine.

[0230] 29. The system according to embodiment 27 or 28 comprises both the at least one first heat exchanger and the at least one second heat exchanger, wherein the at least one first counter-flow heat exchanger and the at least one second counter-flow heat exchanger are the same one or more elements, which can be selectively connected to at least one turbine or at least one compressor in a corresponding energy release mode or energy charging mode.

[0231] 30. The system according to any one of embodiments 1 to 29, comprising at least one pressurizing arrangement configured for pressurizing or propelling the WF after the WF is condensed in the at least one condenser.

[0232] 31. The system of embodiment 30, wherein the arrangement comprises a pump.

[0233] 32. The system of any one of embodiments 1 to 31, comprising at least one first separation zone disposed in at least one turbine, the at least one first separation zone being configured to separate between the WF and the HTL.

[0234] 33. The system according to any one of embodiments 1 to 32, comprising at least one second separation zone disposed in the at least one compressor, the at least one second separation zone being configured to separate between WF and HTL.

[0235] 34. The system of any one of embodiments 1 to 33, comprising at least one pressure reducing nozzle disposed in the second flow path between at least one second heat exchanger and at least one evaporator to reduce the pressure and temperature of WF flowing from the at least one second heat exchanger to the at least one evaporator.

[0236] 35. A system according to any one of embodiments 1 to 34, wherein the WF is a liquid / vapor phase change (LVPhC) WF, which is selected to be: (i) in vapor phase when (1) entering at least one compressor, (2) in temperature equilibrium after mixing with the HTL in at least one turbine, and (3) leaving at least one evaporator; and (ii) in liquid phase when (4) leaving at least one condenser and (5) leaving at least one compressor.

[0237] 36. The system of any one of embodiments 1 to 35, wherein one or both of the at least one compressor and the at least one turbine are thermally insulated.

[0238] 37. The system according to any one of embodiments 1 to 36, comprising one or more selector valves for allowing the at least one hot HTL reservoir to be selectively connected to the at least one compressor or the at least one turbine.

[0239] 38. The system according to any one of embodiments 1 to 37, wherein the HTL is selected from the list consisting of: antifreeze liquid, water, brine, hot oil, molten salt, ethylene glycol, and WF in liquid phase.

[0240] 39. The system of any one of embodiments 1 to 38, wherein WF is selected from the list consisting of: air, nitrogen, hydrogen, CO2, ammonia, propane, ORC phase change material, pentane, refrigeration phase change material.

[0241] 40. The system according to any one of embodiments 1 to 39, comprising at least one external heat source to allow for controllable heating of the hot HTL.

[0242] 41. The system of any one of embodiments 1 to 40, wherein at least one condenser and at least one evaporator are configured to exchange heat with their surroundings for condensation and evaporation, respectively.

[0243] 42. The system of any one of embodiments 1 to 41, wherein at least one evaporator is configured to be heated by at least one external heat source in the charging operating mode.

[0244] 43. The system of embodiment 42, comprising an insulated enclosure including at least one condenser or at least one evaporator configured for heat input from an external heat source and for controlled release of excess heat.

[0245] 44. The system of any one of embodiments 1 to 43, wherein at least one first counter-flow heat exchanger and at least one second counter-flow heat exchanger are regenerators.

[0246] 45. The system of any one of embodiments 1 to 44, wherein at least one intermediate heat exchanger is a regenerator.

[0247] 46. The system of any one of embodiments 1 to 45, wherein the inlet compressor pressure of the WF and the pressure of the WF in the evaporator are below the critical pressure at a temperature lower than the ambient temperature, thereby allowing the WF to evaporate and heat to flow from the ambient to the WF vapor.

[0248] 47. The system of any one of embodiments 1 to 46, wherein the at least one first heat exchanger comprises at least one first thermal pendulum.

[0249] 48. The system of embodiment 47, wherein each of the at least one first heat exchanger comprises a first heat exchanger section, a second heat exchanger section, and a first thermal pendulum section; wherein a flow path of the WF between the first heat exchanger section and the second heat exchanger section is through the thermal pendulum.

[0250] 49. The system of any one of embodiments 1 to 48, wherein the second heat exchanger comprises a second thermal pendulum.

[0251] 50. The system of embodiment 49, wherein each of the at least one second heat exchanger comprises a first heat exchanger section, a second heat exchanger section, and a second thermal pendulum section; wherein a flow path of WF between the first heat exchanger section and the second heat exchanger section is through the second thermal pendulum.

[0252] 51. The system of any one of embodiments 49 and 50, wherein the second thermal pendulum is identical to the first thermal pendulum.

[0253] 52. The system of any one of embodiments 1 to 51, wherein at least one intermediate heat exchanger comprises at least one intermediate heat pendulum.

[0254] 53. A system according to embodiment 52, wherein each of the at least one intermediate heat exchanger includes a first heat exchanger section, a second heat exchanger section and an intermediate thermal pendulum section; wherein the flow path of WF between the first heat exchanger section and the second heat exchanger section is through the thermal pendulum.

[0255] 54. The system according to any one of embodiments 47 to 53, wherein:

[0256] The heat pendulum has a heat capacity greater than the heat capacity of the WF in its liquid phase, and the heat pendulum is configured to exchange heat with the WF passing through the heat pendulum to compensate for inefficient heat exchange between the liquid phase of the WF and the gas phase of the WF, so that (1) in a charging operating mode, the heat pendulum is heated while cooling the liquid before the liquid enters the turbine, and (2) in a discharging operating mode, the heat pendulum is cooled while heating the liquid before the liquid enters the turbine.

[0257] 55. The system of any one of embodiments 1 to 54, wherein the first flow path and the second flow path are closed-loop flow paths.

[0258] 56. A system according to any one of embodiments 1 to 55, wherein at least one turbine is configured to increase the pressure of the HTL to obtain high-pressure HTL, and introduce the high-pressure HTL into the one or more nozzles to mix with the WF at approximately the same pressure to form a HTL / WF mixture, and then the WF is quasi-isothermally expanded within the one or more nozzles to accelerate the HTL / WF mixture toward the outlet of the one or more nozzles.

[0259] 57. A system according to any one of embodiments 1 to 56, wherein at least one compressor includes an HTL pump for increasing the HTL pressure, the HTL pump being fluidly connected to a compressor nozzle, the compressor nozzle being configured to receive pressurized HTL from the HTL pump and to mix the pressurized HTL with WF to obtain an HTL / WF mixture within the nozzle, the HTL / WF mixture being discharged from the nozzle at a pressure higher than the pressure of the WF introduced into the compressor.

[0260] 58. The system of any one of embodiments 1 to 57, wherein at least one WF pump is included within at least one condenser.

[0261] 59. The system of any one of embodiments 1 to 58, wherein the evaporator is maintained at a temperature above ambient.

[0262] 60. The system of any one of embodiments 1 to 59, wherein the compressor HTL is different from the thermal HTL and the compressor HTL has a closed loop flow in the compressor and exchanges heat with the thermal HTL reservoir in the charging mode.

[0263] 61. A system according to any one of embodiments 1 to 60, wherein the compressor HTL is the same as the hot HTL, and the compressor HTL reservoir is the same as the hot HTL reservoir, and in the charging mode, the hot HTL reservoir is connected to at least one two-phase compressor fluid for supplying hot HTL to the at least one compressor.

[0264] 62. A system for converting electrical energy into heat and extracting stored heat as electrical energy, the system comprising:

[0265] The system according to any one of embodiments 1 to 61,

[0266] at least one generator rotationally coupled to the at least one turbine for generating electricity in an energy-discharging mode of operation, and

[0267] At least one electric motor is rotationally coupled to the at least one compressor for operating the compressor to charge the at least one thermal reservoir with heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0268] In order to better understand the subject matter disclosed herein and to illustrate how it may be implemented in practice, various embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0269] Figure 1 is a schematic diagram of a prior art configuration of a thermal energy storage system.

[0270] Figure 2 is a schematic diagram illustrating a two-phase nozzle for both reaction and impulse turbine configurations that mixes compressed gas or steam with the HTL, supports pseudo-isothermal expansion, accelerates the HTL, and generates thrust that is converted into electrical or mechanical work in the turbine.

[0271] Figure 3 is a schematic diagram of a compressor / condenser using an HTL in a closed loop to compress and optionally condense a working fluid.

[0272] Figure 4 is a schematic diagram of the nozzle used in the HTL based compressor / condenser.

[0273] Figures 5A to 5B is a schematic diagram of a system configuration of a non-limiting embodiment of a system including a high temperature HTL reservoir and a low temperature HTL reservoir. Figure 5A The charging mode is illustrated, and Figure 5B The energy release mode is illustrated.

[0274] Figure 6 is a schematic diagram of a rotary slice ball valve used to allow exchange of fluid between high pressure and low pressure sections without wasting work that could be used in the system.

[0275] 7A to 7B are PV and TS diagrams for the system for each mode in an embodiment where WF is gas, wherein, Figure 7A A diagram showing the charging mode, and Figure 7BA diagram showing the energy release pattern.

[0276] Figure 8 is a PV diagram for an isothermal organic cycle using a liquid / vapor phase-changing working fluid.

[0277] Figure 9 Shown is a TS diagram of the thermodynamic cycle using two-phase pentane as the working fluid and ethylene glycol as the HTL.

[0278] FIG. 10A to FIG. 10B is a schematic diagram of a system schema of a non-limiting embodiment of a system using a liquid / vapor phase change working fluid, the system including a high temperature HTL reservoir and a low temperature HTL reservoir. Figure 10A The charging mode is illustrated, and Figure 10B The energy release mode is illustrated.

[0279] Figure 11 The charging mode TS diagram and the releasing mode TS diagram of the isothermal phase change thermodynamic cycle at a fixed pressure level are shown.

[0280] Figure 12 Shown are charging TS diagrams and releasing TS diagrams for an isothermal phase change thermodynamic cycle at varying pressure levels.

[0281] 13A to 13B is a schematic diagram of a non-limiting embodiment of the system including cold and hot HTL reservoirs, two regenerators, and a thermal pendulum. Figure 13A The charging mode is illustrated, and Figure 13B The energy release mode is illustrated.

[0282] FIG. 14A to FIG. 14B is a schematic diagram of a non-limiting embodiment of the system comprising only a high temperature HTL reservoir, a single regenerator, and a compressor and evaporator, which may be the same element. Figure 14A A charging mode including a condenser is illustrated, and Figure 14B A charging mode including an evaporator is illustrated.

[0283] FIG. 15A to FIG. 15B Calculations of the efficiency heat and mass balance for the 140°C temperature case are shown. Figure 15A The energy release mode is illustrated, and Figure 15B The charging mode is illustrated.

[0284] Figure 16 A TS diagram for pentane is shown, illustrating the enthalpy and entropy associated with the calculations, which also includes FIG. 15A to FIG. 15B The case of 140°C is exemplified in FIG.

[0285] 17A to 17Bis a block diagram illustrating a non-limiting embodiment of a system of the present disclosure, wherein the WF exchanges heat with the ambient environment in a condenser / evaporator. DETAILED DESCRIPTION

[0286] The following figures are provided to illustrate embodiments and implementations of the disclosed invention.

[0287] The solution in this disclosure applies the isothermal expansion and compression of a bubble medium to the Carnot battery concept. The liquid in the bubble medium increases the thermal power density per unit volume by 1,000 times, thereby reducing the size and cost of the system, and the bubbles exhibit isothermal expansion and compression, which improves efficiency compared to an adiabatic process.

[0288] The core component of this method and system is a nozzle that mixes compressed gas or steam with a heat transfer liquid (HTL). The HTL remains in a liquid state in the nozzle. Optionally, the vapor is the result of evaporation of a phase change material, which is achieved by mixing the phase change material with the HTL in the nozzle. Optionally, evaporation occurs before reaching the nozzle. The steam or gas mixed with the HTL forms bubbles that expand in the nozzle while maintaining nearly the same temperature as the HTL due to the large heat capacity of the HTL and the excellent heat transfer rate between the steam bubbles and the HTL. The thermal energy density is determined by the HTL and is several orders of magnitude higher than the heat capacity per unit volume of steam. This allows for high power output in narrow pipes and small systems. The expansion accelerates the mixture in the nozzle. Both the HTL and the steam cool as they expand. This temperature drop is less than a few degrees and supports quasi-isothermal expansion of the gas or steam. Optionally, the velocity of the mixture becomes supersonic. In the nozzle, the initial pressure of the HTL and a portion of the thermal energy are converted into kinetic energy under quasi-isothermal conditions. This kinetic energy is used to rotate the turbine, thereby generating electricity, mechanical work, or other forms of work. Examples of such nozzles are described in WO 2022 / 049573, which is incorporated herein by reference in its entirety. For example, molten salt or hot oil is the HTL flowing in the nozzle. Compressed air, nitrogen, ammonia, or other gas is injected into the nozzle, mixed with the HTL, and expanded quasi-isothermally to accelerate the HTL and generate thrust, which is converted into electricity by the turbine. The power generated by the turbine can be partially used to drive a compressor (via a mechanical shaft or electrical connection), which compresses the gas isothermally at low temperatures. The HTL in the turbine is cooled after several cycles and needs to be replaced with a hot HTL to continue converting the heat into work. Figure 2 Illustrated are two-phase nozzles for both reaction and impingement configurations that mix compressed gas or steam with the HTL, support pseudo-isothermal expansion, accelerate the HTL, and generate thrust that is converted to electrical or mechanical work in a turbine.

[0289] For two-phase flows, reaction turbines offer advantages over impulse turbines due to the elimination of cavitation, which can damage impulse turbines. Furthermore, the maximum static pressure at the edge of a reaction turbine is ideal for injecting the gas phase with minimal head loss. Finally, the non-zero velocity of the exiting jet in a reaction turbine serves to separate the gas / liquid mixture by causing the jet to impinge on the circular frame, inducing thin film flow on the frame's walls and defining a separation zone, wherein the thin film flow induced on the frame's walls breaks up the gas bubbles.

[0290] Another core component is the continuous isothermal compressor and condenser: The term "compressor" is used to compress a gas or vapor, which remains as compressed gas or vapor. The term "condenser" describes the same device, but the compressed vapor is liquefied.

[0291] Optionally, the HTL in the compressor / condenser is water, an organic liquid such as ethylene glycol, an organic material identical to an organic vapor in liquid phase, or any other liquid having a liquid phase at operating temperature. The HTL inlet temperature is between -200 degrees Celsius and 1000 degrees Celsius or higher. Low-temperature HTL is optionally used to compress or liquefy air, nitrogen, hydrogen, CO2, or any other gas for charging a cold reservoir. High-temperature HTL is optionally used to charge a hot reservoir. This is achieved by insulating the compressor so that all work invested is converted into pressure and temperature to be preserved. In this adiabatic system, due to the large heat capacity of the liquid, compression is quasi-isothermal, which keeps the compressed gas at a low temperature compared to conventional adiabatic expansion in which the gas is not mixed with the HTL. In addition, a moderate temperature difference of 50°C, 100°C, or 200°C is optionally used for the hot and cold reservoirs.

[0292] Figure 3An alternative method and system for condensing and compressing gas or vapor is described in [1]. The system is designed to increase the surface area between the compressed liquid and the compressed gas or vapor, thereby reducing the size and cost of the compressor. The closed-loop flow of the HTL is driven by a pump at a higher pressure than the incoming gas or vapor. The nozzle is designed to reduce the pressure to below the incoming gas or vapor pressure. This allows the gas or vapor to be drawn into the HTL flow. The gas or vapor enters from the outer envelope or through a designated pipe. The gas or vapor and HTL mix within the nozzle. In the case of steam, the HTL temperature and its high heat capacity per unit volume of steam optionally liquefy the vapor. After mixing, the nozzle shape is designed to increase the pressure at the nozzle outlet to above the inlet pressure. Optionally, in the case of steam, a portion of the phase change material remains in the vapor phase and is compressed into gas. Optionally, the majority of the vapor is liquefied after the pressure is increased above the critical pressure. Optionally, the gas / HTL or steam / HTL mixture reduces the speed of sound to below the flow velocity of the mixture, resulting in supersonic flow in the nozzle. In this case, the design of the reverse De Laval nozzle is as follows. Optionally, the compression is isothermal or quasi-isothermal, which means that the HTL and the gas or steam maintain similar temperatures as the compression is measured in Kelvin, with a difference of less than 10% or 20%. Optionally, after the nozzle, the pressure increases, the flow slows down, and the mixture is separated by gravity or centrifugation or any other separation method. The gas phase, vapor phase or liquid phase of the phase change material is collected (in the upper part when the density of the phase change material is lower than that of the HTL), and the HTL reaches the pump and continues to circulate. The HTL is heated as the compression is carried out. Optionally, the hot HTL is replaced with a cooled HTL to allow the compressor to operate continuously (not shown in the figure). Optionally, without replacing the HTL, the HTL is cooled by transferring heat to the surrounding environment through the surface of the flow. Optionally, the HTL is heated to store thermal energy. Optionally, the compressor pressure at the suction port is lower than the ambient pressure. For example, it is 0.7 bar. This allows the compressor to operate between the maximum compression pressure and the minimum inlet pressure, which in this example is 0.7 bar. Under steady-state conditions, the HTL temperature can be high enough to cause the HTL to evaporate at low pressure in the low-pressure zone. In this case, the flow duration in the low-pressure zone is much shorter than the heat exchange rate. In other words, the HTL does not have enough time to absorb the heat of evaporation from the environment and remain liquid, which allows the HTL and the steam to be the same material. For example, liquid pentane used as the HTL flow in the compressor compresses pentane vapor. In the low-pressure zone, conditions support the gas phase, but as long as the flow in the low-pressure zone is faster than the heat transfer rate, there is no phase change. Instead, the liquid absorbs the pentane vapor from the turbine, causing the pentane vapor to condense and compress the pentane vapor. The advantage is that phase separation (bubbles) in the compression stage is eliminated, which speeds up the condensation process.

[0293] like Figure 4 The nozzle of the compressor illustrated in FIG may include the following sections in order:

[0294] 1. Converging inlet section for reducing pressure above ambient pressure, including only HTL (water as a non-limiting example).

[0295] 2. A diverging two-phase flow section, in which the pressure remains constant while gas or vapor (air as a non-limiting example) is drawn from the environment into the HTL through holes or gaps in the nozzle envelope. The section marked "-" is where the inhalation begins, and the section marked "+" is where the inhalation ends. The mixture reduces the speed of sound to below the speed of the mixture. At the end of the "diverging two-phase flow section" (marked with a "+"), the flow is supersonic. (For supersonic two-phase flow, see the reference "Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting Nozzle With a Throat," Sowmitra Singh, Tiffany Fourmeau, Jin Keun Choi, Georges, and L. Chahine, DOI: 10.1115 / 1.4026855)

[0296] 3. A converging two-phase section, where the mixture pressure increases and the Mach number (the ratio of the flow velocity to the speed of sound) decreases. At the end of this section, marked with an "*," the Mach number = 1. (For supersonic two-phase flow, see the reference "Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting Nozzle With a Throat," Sowmitra Singh, Tiffany Fourmeau, Jin Keun Choi, Georges, and L. Chahine, DOI: 10.1115 / 1.4026855.)

[0297] 4. Diverging two-phase exit: In this section, the mixture pressure increases and the Mach number decreases. At the end of this section, the mixture reaches its maximum pressure (in the form of a mixture, since the HTL itself has a higher pressure when it is introduced into the nozzle) (For supersonic two-phase flow, see the reference "Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting Nozzle With a Throat", Sowmitra Singh, Tiffany Fourmeau, Jin Keun Choi, Georges, and L. Chahine, DOI: 10.1115 / 1.4026855).

[0298] Referring back to the system, in one configuration of the system, the storage system includes a high-temperature HTL reservoir and a low-temperature HTL reservoir, a quasi-isothermal adiabatic compressor, an adiabatic turbine, a working fluid in the form of a gas, a heat exchanger for the gas, and an HTL. The gas can be nitrogen, air, CO2, or any other gas, and the HTL can be any liquid that remains liquid in the operating temperature range between the two HTL reservoirs. Optionally, a different HTL is used for the high-temperature reservoir than for the low-temperature reservoir. This requires a filter to prevent the two HTLs from mixing. Optionally, the same HTL is used in both reservoirs. During the charging process, an electrical input or mechanical power input is used to create a temperature difference between the high-temperature T_h HTL reservoir and the cold-temperature T_c HTL reservoir. During the discharge process, the temperature difference is converted into output electricity.

[0299] Examples of materials and operating temperatures of the storage system: In the temperature range of -40°C to 200°C, nitrogen gas is used as the working fluid (WF) and ethylene glycol is used as the HTL. Alternatively, ethylene glycol mixed with water is the HTL.

[0300] exist Figure 5AThe charging process is depicted in Figure 2. Electricity drives the quasi-isothermal adiabatic compressor. Nitrogen is compressed from a low pressure, P_L, to a high pressure, P_h, and is heated to T_h by the HTL. The temperature of the compressed nitrogen and HTL continues to rise as the compressor operates, reaching a maximum value, T_h_max = 199°C in the case of ethylene glycol. As the compressor operates, the compressed nitrogen leaves the compressor at any T_h value between T_L and T_h_max and enters the heat exchanger, where its temperature is reduced to a low temperature, T_c. The cold, compressed nitrogen enters the turbine and expands quasi-isothermally in the nozzle, accelerating and cooling the HTL, thereby generating thrust, which is converted into electrical or mechanical work in the turbine. This electrical or mechanical work supports compressor operation, reducing the external power required. The HTL and gas in the turbine cool as they expand. The HTL remains in the turbine and cools with each cycle until it reaches a minimum temperature, T_L_min. The cooled nitrogen is returned to the heat exchanger, thereby recovering heat and raising its temperature to T_h. As the gas returns to the compressor, the cycle continues. After several cycles, the temperature difference reaches a maximum value (-40°C and 199°C for ethylene glycol). Optionally, a hot HTL reservoir and a cold HTL reservoir are connected to the compressor and the turbine for charging the reservoir. The turbine is optionally connected to the cold HTL reservoir via a circulating pump for replacing the HTL. The compressor remains at high pressure. Optionally, the hot HTL reservoir connected to the compressor is also at high pressure.

[0301] Since the same amount of liquid can be fed into and withdrawn from the compression tank without doing work (the volume of the compressed gas does not change), the thermal reservoir can be kept at a low pressure by the compressor while the HTL is being mixed. Alternatively, this can be achieved by simultaneously injecting and withdrawing the same amount of liquid into and from the compressor. Figure 6 An alternative mechanism for doing this is shown. A set of ball valves, blocked from direct flow, are positioned at the wall between the high-pressure P_h side and the low-pressure P_L side. The HTL fills the empty space in the ball valves. The ball valves are rotated to exchange liquids without requiring a large amount of work.

[0302] Can be Figure 7A The charging process is described in the PV / TS diagram depicted in [1]. This charging process operates as a reverse Ericsson thermodynamic cycle. The compressor performs compression at high temperature using a hot reservoir. The gas is compressed quasi-isothermally due to mixing with the HTL. The gas is then cooled in a heat exchanger, optionally at constant pressure, and passes to a turbine connected to a cold reservoir, where it expands quasi-isothermally.

[0303] For discharging, the connections of the reservoirs are switched so that the hot reservoir exchanges HTL with the turbine and the cold reservoir exchanges HTL with the compressor. Figure 5B The energy release pattern is depicted in . To accelerate, the compressor keeps the nitrogen compressed. Alternatively, a separate chamber for compressed nitrogen can be used for acceleration. Once the valve is opened at the compressor or chamber, the compressed nitrogen passes through a heat exchanger at high pressure P_h and cold temperature T_c, reaches the turbine at high temperature T_h, mixes with the hot HTL in the nozzle, expands quasi-isothermally, and generates thrust, which is converted into electrical or mechanical work in the turbine. A portion of the electrical or mechanical work is transferred to the compressor. The HTL and nitrogen cool as they expand in each cycle. The nitrogen returns to the heat exchanger at the hot HTL temperature T_h and low pressure P_L, and leaves the heat exchanger at T_c. The nitrogen then reaches the compressor, where it is compressed quasi-isothermally at the cold compressor temperature T_c. The energy balance is positive because compressing the gas at low temperature and expanding it at high temperature generates work, just like in a heat engine. The cycle continues as long as the temperature difference supports the generation of positive energy.

[0304] Can be Figure 7B The energy release process is described in the PV and TS diagrams depicted in [1]. The energy release process operates as an Ericsson thermodynamic cycle. The compressor performs compression at low temperatures using a cold reservoir. The gas is compressed quasi-isothermally due to mixing with the HTL. The gas is then heated in a heat exchanger, optionally at a constant pressure, and reaches a turbine connected to the hot reservoir, where it expands quasi-isothermally.

[0305] The above system is designed to store electrical energy through thermal energy and convert the thermal energy back into electricity. Optionally, if a hot or cold heat source is available, the hot or cold reservoir exchanges heat with the source to reach the desired temperature without the input of electricity. In this case, the second reservoir is at ambient temperature, and the amount of electricity that can be extracted depends on the temperature difference between the heated (or cooled) reservoir and the ambient temperature. Optionally, in addition to the heat source, electricity is used to further increase the temperature difference between the sources to be converted into electricity. Alternatively, if the cold reservoir is at a higher temperature than the environment, air can be used to cool the cold reservoir, resulting in more electricity being extracted.

[0306] Alternatively, the nitrogen example can be replaced with an organic material, as in an organic Rankine cycle (ORC). In this case, the electricity used in the compressor condenses the vapor into a liquid, as in an ORC. The liquid evaporates in the nozzle of the turbine and expands quasi-isothermally in the turbine, where it cools the HTL. The ORC material then passes through a heat exchanger and returns to the compressor / condenser for another cycle. As an example, an ORC material such as ethylene glycol is used as the HTL and propane is used as the working fluid. Any other ORC material can be considered to have a liquid phase at cold HTL temperatures and a gas phase at hot HTL temperatures.

[0307] Optionally, the hot reservoir is heated by an external heat source. Optionally, the cold reservoir is cooled by an external source, such as water flow or air ventilation. Optionally, ventilation or other external work input is used to slow the cooling rate of the hot reservoir during the energy discharge period.

[0308] At low temperatures (<200°C), the round-trip efficiency of a typical Ericsson-based Carnot cell is less than 50% due to the increased work of the compressor. The present invention utilizes a new thermodynamic cycle based on isothermal bubble expansion of an organic liquid / vapor phase change (LVPhC) working fluid in a two-phase nozzle. For Carnot cells, this new engine offers advantages over the Ericsson cycle operating at low temperatures because the phase change limits the pressure rise, thereby reducing the compressor load.

[0309] The method is optionally described by the stages of a thermodynamic cycle:

[0310] 1->2: Liquefied LVPhC is pumped from the condenser and pressurized to a pressure P1 that is similar or close to the pressure in the mixing chamber in the nozzle.

[0311] 2->3: The liquefied LVPhC exchanges heat with the steam leaving the turbine, increasing the temperature of the liquefied LVPhC without phase change (due to the high latent heat, the liquefied LVPhC remains liquid). Optionally, a portion of the LVPhC evaporates.

[0312] 3->4: The compressed liquid (and optionally steam) LVPhC is injected into the evaporator where it is evaporated. Optionally, this stage is completed in the nozzle.

[0313] 4->5: Compressed LVPhC steam mixes with HTL in a mixing chamber within the nozzle, where the HTL flows. The decreasing static pressure and temperature within the nozzle cause quasi-isothermal expansion, accelerating the LVPhC / HTL mixture and generating thrust at the nozzle's exit. This thrust rotates the turbine, generating electricity, mechanical work, or other forms of power. Optionally, the mixture's velocity is supersonic within a portion of the nozzle.

[0314] 5->6: The high-temperature steam (LVPhC) vapor exits the nozzle, separates from the HTL, and flows to a heat exchanger where it exchanges heat with the liquid (LVPhC) vapor exiting the condenser without a phase change (the vapor remains as vapor). Optionally, a portion of the vapor condenses.

[0315] 6->1: The steam is cooled until it condenses in the condenser and is compressed into a liquid.

[0316] exist Figure 8 The PV diagram of the thermodynamic cycle is shown in .

[0317] Examples of LVPhC materials are antifreeze materials such as ORC conventional materials: pentane, isobutane, propane, R134a, R245fa, fluorocarbons and toluene.

[0318] Figure 9 The following table describes an example of controlled volume calculations for thermodynamic cycles using two-phase pentane and using ethylene glycol as HTL.

[0319] Consider 1 kg of pentane, where the numbers in the TS diagram are P0 = 1 bar, P1 = 14.5 bar, T1 = 155 ° C, T HTL_冷 = Different thermodynamic states at 35°C:

[0320] 6->1: Condensation: 342KJ / Kg.

[0321] 1->2: The pumped LVPhC-liquid is isentropically compressed to P1: 4 kJ / kg.

[0322] 2->3a: Assuming a 30-degree difference, the heat exchange between LVPhC-liquid and LVPhC-steam is 146 kJ / kg.

[0323] 3a->3: Additional heat from HTL reaches the liquid-vapor equilibrium point at P1: 144K J / Kg.

[0324] 3->4: LVPhC - liquid evaporates and heats the steam to 155°C: 246 KJ / Kg.

[0325] 4->5: LVPhC - steam expansion in nozzle - isothermal work: 133KJ / Kg.

[0326] 5->6: Steam cooling in heat exchange: 146KJ / Kg.

[0327] This calculation shows the cycle efficiency

[0328] When assuming an ideal heat exchanger (0°C temperature difference) and an ideal compressor and turbine, the efficiency reaches the Carnot efficiency, which is double the efficiency of a conventional ORC under similar conditions.

[0329] We note that for the two-phase nozzle, superheating is optional, and supercriticality (mixed vapor / liquid phases) is also optional due to the bubbling mixture flow in the nozzle. In this option, the line between points 3 and 5 in Figure 10 does not intersect the phase change bell-shaped dashed line.

[0330] Using such an engine typically requires a heat source to vaporize the working fluid, evaporating and accelerating the mixture in the nozzle, generating thrust and spinning the turbine. A condenser is then used to cool and liquefy the steam for reheating and recovery in the turbine.

[0331] For a Carnot cell, the system includes a compressor / condenser that optionally isothermally compresses / condenses steam; an isothermal expansion / evaporation turbine; and a regenerator, a counter-flow heat exchanger, between the compressor / condenser and the isothermal expansion / evaporation turbine.

[0332] Figure 10A An optional charging process is depicted. The vapor-LVPhC condenses in a compressor / condenser operating on an external power source. The heat generated heats the HTL and the hot reservoir. The hot liquid-LVPhC then passes through a regenerator and cools, reaching the turbine. In the turbine, the pressure drops, causing the liquid-LVPhC to evaporate and expand in the nozzle, rotating the turbine and generating power that returns to the compressor. The cooled vapor-LVPhC cools the reservoir, enters the regenerator, and returns to the compressor for another cycle. In this way, the power (electricity) invested in the compressor is converted into the hot and cold reservoirs.

[0333] In discharge mode, the turbine HTL is connected to the hot reservoir and the compressor / condenser is connected to the cold reservoir HTL. Figure 10BAn optional energy release process is depicted. During compressor / condenser operation, the vapor-LVPhC condenses at the cold reservoir temperature. The generated heat heats the HTL and the cold reservoir. The liquid-LVPhC then passes through the regenerator and is heated, reaching the turbine. In the turbine, the heat and pressure drop cause the liquid-LVPhC to evaporate and expand in the nozzle, rotating the turbine and generating electricity that is returned to the grid, part of which supports the compressor. The hot vapor-LVPhC cools the hot reservoir, enters the regenerator, and returns to the compressor for another cycle. In this way, by using both the cold and hot reservoirs, work (electricity) is returned to the grid.

[0334] Optionally, an isothermal compressor / condenser is included Figure 4 , which is a two-phase Laval nozzle of "reverse" configuration as described above, so that it increases the pressure of the gas by mixing it with the HTL, thereby isothermally compressing the gas. It should be noted that this figure is not drawn to scale.

[0335] HTL, such as water, low freezing point liquid, bicarbonate liquid and / or other streams in the nozzle enter the inlet at a higher pressure than the ambient pressure and leave at the outlet at a higher pressure than the ambient pressure. Gas, such as air, hydrogen or any other gas is drawn into the HTL, compressed and cooled by the HTL, and discharged at the outlet at a higher pressure than the ambient pressure. Although Figure 4 While water is shown as the HTL and air is used as the gas, it should be noted that the HTL can be selected from any suitable HTL, and the gas can be any suitable gas to be compressed. Optionally, the HTL initial pressure and velocity are generated by a pump. Optionally, the initial and final pressure values of the HTL are identical, with a difference of no more than 10%. Optionally, the initial and final pressure values of the HTL are identical, with a difference of no more than 20% or 30%.

[0336] Preferably, the operating temperature of the HTL is as low as possible. Optionally, it is below 100°C, 25°C, 15°C, or 0°C. Optionally, for low-freezing-point HTL, the operating temperature is below -10°C, -25°C, or -50°C. Optionally, when the HTL is liquid nitrogen, the HTL temperature is below -195°C, or when the HTL is liquid helium, the HTL temperature is below 4.2K.

[0337] Alternatively, such compressors can be used in a cascaded fashion to achieve higher pressures, bringing the compressed gas to the gas supply of a second closed-loop compressor to achieve the second-stage pressure. For example, using water as the HTL and a supersonic nozzle, the first stage compresses the air to 15 bar. This compressed air flows into the second supersonic nozzle of the second compressor closed loop, which is maintained at approximately 30 bar. At the nozzle, the pressure drops below 15 bar, allowing air to enter. At the nozzle outlet, the pressure increases to 30 bar, and the air is compressed and simultaneously cooled by water.

[0338] The system optionally includes pentane as a working fluid, or optionally cyclopentane for temperatures above 180°C. HTLs, for example, are ethylene glycol operating up to 200°C or hot oil up to approximately 400°C, and even molten salts for higher temperatures. Alternative working fluids are any of the fluids used in conventional ORCs, such as pentane, isobutane, propane, R134a, R245fa, fluorocarbons, and toluene. For high temperatures, water can be used as the working fluid, as in the Rankine cycle.

[0339] Figure 11 An example of the temperature evolution during charging and discharging is shown. In this example, a fixed low pressure (1 bar) and a fixed high pressure (14.5 bar) are reached at any point in the cycle, regardless of the temperature. For example, the starting reservoir temperatures are optionally 90°C and 111°C. In the figure, the thermodynamic cycle is described by points 5.1 to 3.1 (compressor / condenser) and 1.1 to 6.1 (turbine evaporation / expansion).

[0340] Alternatively, the end pressure reached by the turbine and compressor is set by the saturation pressure. This requires varying the pressure according to the temperature profile of this option, where the cold side remains at a fixed temperature while the hot reservoir varies the temperature built up by the reservoir. Figure 12 This option is depicted.

[0341] Alternatively, any combination of fixed pressure and variable pressure can be considered. For example, charging the system at variable pressure ( Figure 12 ), while the energy released at constant pressure ( Figure 11 Alternatively, in the event that the cold reservoir temperature exceeds the ambient temperature, the cold reservoir or the compressor / condenser can be thermally connected to the ambient to maintain a lower temperature than would be achieved if the system were insulated. This will increase the amount of power extracted.

[0342] Furthermore, because the working fluid has a higher inherent heat capacity in its liquid phase compared to its vapor phase, the liquid arrives at the turbine hotter than the turbine during charging, while cooler during discharge. This reduces overall round-trip efficiency by masking temperature differences between the reservoirs. Since the total net heat transfer of the liquid during a complete charging-discharging cycle is zero, a high-heat-capacity body can optionally be incorporated into the regenerator heat exchanger and used as a thermal pendulum to transfer the missing thermal energy. While the liquid phase exchanges heat with the vapor phase in the regenerator, at the thermal pendulum, only the liquid phase flows, exchanging heat with the thermal mass. Figure 13A Shown is a separated regenerator (heat exchanger) in charging mode with a hot pendulum in the middle where the temperature varies minimally. In charging mode the hot pendulum heats up while cooling the liquid before it reaches the turbine. Figure 13B The energy release mode is shown, where the thermal pendulum cools while heating the liquid before it reaches the turbine. The net energy on the pendulum is zero.

[0343] Generally speaking, the main advantage of the Carnot battery is its ability to be converted into a heat engine configuration. That is, when the thermal storage is depleted, the energy-releasing configuration becomes a heat engine, while the thermal reservoir is replaced by combustion of gas or hydrogen, or any other combustion process. This allows the device to provide power year-round, even when the thermal storage is depleted.

[0344] In an optional Carnot cell configuration, one reservoir can be the ambient environment. The advantage is that costs are reduced by eliminating one reservoir. In an optional configuration of the system, only the hot reservoir is used, and the cold reservoir is the ambient environment. In this case, the working fluid is optionally pentane, cyclopentane, water, or any other working fluid for a two-phase steam / HTL heat engine. Alternatively, the HTL is ethylene glycol, hot oil, molten salt, or other non-evaporating liquid within the operating temperature and pressure range of the system. Optionally, in an energy-releasing configuration, combustion gas, hydrogen, or other combustion processes can be used to heat the working fluid and HTL to generate electricity.

[0345] Figure 17Ais a block diagram illustrating a non-limiting embodiment of a system of the present disclosure, wherein a WF exchanges heat with the ambient environment in a condenser / evaporator. The system 100 includes a high temperature HTL reservoir 102 (throughout the application, the term "high temperature HTL reservoir" is interchangeable with the term "hot HTL reservoir" or "hot HTL reservoir"), which is selectively connected to a turbine 104 in a discharge mode and to a compressor 106 in a charging mode. When the high temperature HTL reservoir 102 is fluidly connected to the turbine 104 or the compressor 106, the high temperature HTL reservoir 102 exchanges HTL with the corresponding component. In the charging mode, the temperature of the HTL delivered to the compressor 106 is lower than the temperature of the HTL received back from the compressor 106. In the discharge mode, the temperature of the HTL delivered to the turbine 104 is higher than the temperature of the HTL received back from the turbine 104.

[0346] In each operating mode, the WF flows in a different closed-loop flow path.

[0347] In the discharge mode, WF flows in a first flow path from the turbine 104 to the counterflow heat exchanger 108, to the condenser / evaporator 110 serving as a condenser, back to the counterflow heat exchanger 108, and back to the turbine 104. In its flow path, the WF is pressurized by a WF pump (not shown) after being condensed and before the WF enters the nozzle of the turbine 104.

[0348] In the charging mode, the WF flows in a second flow path from the compressor 106 to the counterflow heat exchanger 108, to the condenser / evaporator 110, which functions as an evaporator, back to the counterflow heat exchanger 108, and back to the compressor 106. Typically, the pressure of the WF is reduced between flows from the counterflow heat exchanger 108 to the evaporator 110, for example, by a dedicated pressure-reducing nozzle, in order to reduce the temperature of the WF to below ambient pressure to allow the WF to receive heat from the surrounding environment as it passes through the evaporator 110.

[0349] Figure 17B is another block diagram illustrating a different non-limiting embodiment of the system of the present disclosure, wherein the WF exchanges heat with the ambient environment in the condenser / evaporator. Figure 17B and Figure 17AThe difference between the WF and the WF is that the compressor 106 includes its own compressor HTL 107, which flows in a closed loop within the compressor 106 and does not receive hot HTL from the high-temperature HTL reservoir 102. The compressor 106 also includes a compressor HTL reservoir 109, which stores the compressor HTL 107 before and / or after the compression process in the compressor. The compressor HTL reservoir 109 can be in the form of a chamber, or can be a portion of the compressor HTL flow path in the compressor that is different from the operating area where compression occurs. The compressor HTL gradually increases its temperature with each compression cycle of the WF, and the compressor is configured to exchange heat with the hot HTL reservoir to heat the hot HTL reservoir. The heat exchange can be achieved by designing a portion of the closed-loop flow path of the compressor HTL to be thermally coupled to the high-temperature HTL reservoir or the flow path of the hot HTL, but without any liquid exchange between the compressor 106 and the high-temperature HTL reservoir 102. It should be noted that embodiments in which the compressor includes its own HTL and is thermally coupled only to the HTL reservoir can be applied to any aspect of the present disclosure. Thus, in aspects that also include a cold HTL reservoir, the compressor can also be thermally coupled to the cold HTL reservoir but not exchange liquid with the cold HTL reservoir.

[0350] A more specific example of this system configuration is FIG. 14A to FIG. 14B , wherein during the energy release process ( Figure 14A ), the turbine is connected to the hot reservoir and condenser via a regenerator (the condenser's surroundings are the cold reservoir). Optionally, the working fluid (WF) is cyclopentane. In this option, the liquid WF is pressurized (pumped), heated in the regenerator, and injected into the turbine, where it is further heated, evaporated, and expanded quasi-isothermally, cooling the hot reservoir. The generated electricity operates the condenser and delivers net output power. The steam continues into the regenerator, cools, and condenses in the condenser, returning to the regenerator. This process ends when the temperature difference between the reservoirs becomes too small. Figure 14A The TS diagram for this process is shown on the right. The different thermodynamic stages 3.0-5.0, 3.1-5.1, 3.2-5.2, 5.3-3.3 describe the evaporation and expansion of the heat reservoir at high temperature as energy is released (cooling) by the turbine.

[0351] During the charging process ( Figure 14B), the compressor / condenser is connected to a heat reservoir and is driven by external electricity. The WF vapor is compressed and condensed, while heat flows from the WF to the heat reservoir, thereby raising the temperature of the WF vapor. The liquid WF is cooled in the regenerator. Flash evaporation or other pressure reduction methods are used to flash a portion of the WF, while the WF is cooled to a temperature below the ambient temperature. The WF continues to evaporate in the evaporator, while heat flows from the ambient environment to the WF. In this example, the evaporator is the same device as the condenser. The input vapor pressure in the compressor is the same as the pressure in the evaporator. The input vapor pressure is controlled to allow evaporation at a saturation temperature lower than the ambient temperature. Lowering the pressure lowers the saturation temperature. The high-pressure liquid WF leaving the compressor passes through a pressure reducing nozzle, optionally an orifice, which reduces the pressure to the level of the compressor inlet pressure. The result is that the WF evaporates while cooling to a temperature lower than the ambient temperature. This allows heat to flow from the ambient environment into the cooled WF, thereby supporting further evaporation. The result is that the WF vapor approaches the ambient temperature. The steam returns to the regenerator, is heated in the compressor / condenser and compressed again quasi-isothermally, thereby heating the heat reservoir. The process ends when the temperature is high enough.

[0352] Example of such a system: 250kW Carnot Battery (CB), optionally operated as a peaking gas turbine when storage is depleted.

[0353] CB is evaluated by two parameters: engine efficiency and heat pump efficiency, i.e. coefficient of performance (CoP). Ideally, when charging and discharging operate between the same temperatures, these two parameters cancel each other out, resulting in a round-trip efficiency of 100%. In this solution, the engine and storage are operated over a certain temperature range. At low temperatures (100°C < 140°C), the high CoP compensates for the low efficiency, while at high temperatures (140°C > 180°C), the high engine efficiency compensates for the low CoP. Table 1 summarizes the actual efficiency of the pentane turbine, which is calculated by operating the heat and mass balance at different temperatures ( Figure 13A Calculated based on the settings in .

[0354] Table 1:

[0355] Engine efficiency at different temperatures

[0356] T(℃) efficiency(%) 100 12.5 140 18.75 175 23.1 250 29.9

[0357] Figure 15A The heat and mass balance is shown for a temperature of 140°C, which shows an efficiency of 18.75%.

[0358] Figure 16The enthalpy and entropy of pentane at different temperatures are plotted. The CoP during charging is defined by stage 5-3 of the heat pump in the high temperature range, where heat is: Q=Tds, work is W=Q-dH, and CoP=Q / W.

[0359] As an example, we consider two case studies:

[0360] CB as an independent dispatchable source. In this configuration, the pressure in the evaporator is set to 0.38 bar (saturation temperature at T = 10°C) when charging. This allows evaporation at ambient temperature. At the temperature of the reservoir (and HTL in the compressor), the compressor inlet pressure is 0.38 bar and the outlet pressure is slightly above the saturation pressure.

[0361] The CB adds an additional waste heat source at 75°C to heat the evaporator. The 75°C waste heat allows pentane to evaporate at 70°C and 2.8 bar pressure. This initial pressure reduces the work in the 5-3 stage while maintaining the latent heat extracted to the reservoir. This external waste heat source improves both CoP and CB efficiency, optionally to above 100%.

[0362] Table 2 summarizes the extracted thermodynamic CoP for Case 1 (ambient) and Case 2 (75°C) at various HTL temperatures. In practice, since the compressor is in the high-temperature section, the heat losses are recovered. With an 80% pump efficiency for the compressor and a CoP of 4, the effective efficiency is 85% (0.8 + 0.2 / 4 = 0.85). The actual value of 80% pump efficiency is marked in bold in Table 2. Clearly, the 75°C waste heat source more than doubles the CoP compared to ambient temperature. The total round-trip efficiency (power out / power in) is the product of the CoP and the efficiency of the energy-discharging engine (Table 1).

[0363] Table 2: CoP at different temperatures

[0364]

[0365]

[0366] Table 3 summarizes the return cycle efficiencies.

[0367] Table 3: Round trip efficiency at different temperatures

[0368] 175℃ 140℃ 100℃ RT efficiency (case-1) 0.58 0.46 0.40 RT efficiency (case-2) 0.86 0.84 1.2

[0369] It is clear that the 75°C waste heat source provides an average round-trip efficiency of >90%. In both cases, when the heat storage is depleted, combustion gas or hydrogen drives the engine. Calculating the heat and mass balance for pentane at 250°C gives an efficiency of 30%.

[0370] To complete the picture, Figure 15B The heat and mass balance for the charge of a 250 kW turbine at 140°C is shown (the system is set up as Figure 14B (shown). The heat and mass balance supports a round-trip efficiency of 84%. In this configuration of the system, the evaporator can be housed within an enclosure that receives the waste heat. The enclosure can have an inlet for receiving the waste heat and an outlet for venting when a large amount of waste heat is introduced.

[0371] Given the prevalence of 75°C waste heat, achieving 84% battery efficiency and 30% peaking turbine efficiency allows for the storage of excess power from renewable energy-based grids, thereby providing a baseload renewable grid – a crucial step towards a fully decarbonized grid. Another advantage is the decoupling of energy charging (compressors) from energy dissipation (turbines). Renewable energy sources such as solar and wind can be charged for a few hours per day, while energy dissipation can be nearly continuous. This requires large compressors and small turbines.

Claims

1. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising: at least one hot transfer fluid (HTL) reservoir, the at least one hot transfer fluid reservoir containing a hot transfer fluid; at least one two-phase turbine and at least one two-phase compressor, said at least one two-phase compressor being configured to compress a compressor heat transfer fluid that is the same as or different from said hot heat transfer fluid of said thermal reservoir; wherein the at least one hot heat transfer fluid reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot heat transfer fluid to the corresponding turbine in the discharge mode or for (2) exchanging heat between the compressor heat transfer fluid and the heat transfer fluid in the heat transfer fluid reservoir when the compressor heat transfer fluid is different from the hot heat transfer fluid and when the compressor heat transfer fluid is different from the hot heat transfer fluid reservoir, or supplying the hot heat transfer fluid to the at least one compressor when the compressor heat transfer fluid is the same as the hot heat transfer fluid and when the compressor heat transfer fluid reservoir is the same as the hot heat transfer fluid reservoir; at least one condenser in fluid communication with the turbine for receiving a working fluid (WF) from the turbine and condensing the working fluid; at least one evaporator in fluid communication with the at least one compressor for receiving a working fluid from the at least one compressor and evaporating the working fluid, the at least one evaporator being the same or a different element from the at least one condenser; The discharge mode defines a first flow path for the working fluid, and the charge mode defines a second flow path for the working fluid; and Wherein, in the energy release mode, the working fluid flows from the at least one condenser in the first flow path to one or more nozzles in the at least one turbine, and the nozzle is configured to cause the turbine to rotate when the fluid is discharged from the nozzle, thereby mixing the working fluid with the heat transfer fluid to form a heat transfer fluid / working fluid mixture in the one or more nozzles, and in the one or more nozzles, the working fluid undergoes quasi-isothermal expansion, thereby accelerating the heat transfer fluid / working fluid mixture and causing the mixture to be discharged through the one or more nozzles while reducing the temperature of the heat transfer fluid, and the heat transfer fluid / working fluid mixture discharged from the one or more nozzles is received in at least one first separation zone, which is configured to separate the working fluid from the heat transfer fluid, and the heat transfer fluid is recycled back to the at least one heat storage tank or the one or more nozzles, and the separated working fluid flows into the condenser and is received in the condenser to undergo condensation in the condenser, and the condensed working fluid discharged from the at least one condenser flows back to the turbine.

2. The system according to claim 1 includes at least one first counter-flow heat exchanger, which is arranged between the at least one turbine and the at least one condenser in the first flow path and is configured to perform heat exchange between the working fluid exiting from the at least one turbine and the working fluid exiting from the at least one condenser.

3. The system according to claim 2, wherein: The heat exchanger is configured to reduce the temperature of a working fluid flowing from the turbine to the condenser.

4. The system of any one of claims 1 to 3, comprising at least one pressurizing arrangement configured to pressurize or advance the working fluid after it is condensed in the at least one condenser.

5. The system according to claim 4, wherein: The arrangement comprises a pump.

6. The system of any one of claims 1 to 5, comprising at least one first separation zone disposed in the at least one turbine, the first separation zone being configured to separate between a working fluid and a heat transfer fluid.

7. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising: at least one hot heat transfer fluid reservoir, the at least one hot heat transfer fluid reservoir containing a hot heat transfer fluid; at least one two-phase turbine and at least one two-phase compressor, the at least one two-phase compressor being configured to compress a compressor heat transfer fluid that is the same as or different from the heat transfer fluid of the thermal reservoir; The at least one hot heat transfer fluid reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot heat transfer fluid to the corresponding turbine in the discharge operating mode or for (2) exchanging heat between the compressor heat transfer fluid and the heat transfer fluid in the hot heat transfer fluid reservoir; at least one condenser in fluid communication with the turbine for receiving a working fluid, ie, a working fluid, from the turbine and condensing the working fluid; at least one evaporator in fluid communication with the at least one compressor for receiving a working fluid from the at least one compressor and evaporating the working fluid, the at least one evaporator being the same or a different element from the at least one condenser; The discharge mode defines a first flow path for the working fluid, and the charge mode defines a second flow path for the working fluid; and Wherein, in the charging mode, the working fluid flows in the second flow path, and the at least one compressor is configured to form a compressor heat transfer fluid / working fluid mixture, and quasi-isothermally compress the working fluid in the mixture along the compressor flow path, and thereby heat the compressor heat transfer fluid, the compressor heat transfer fluid exchanges heat with the hot heat transfer fluid reservoir, thereby heating the hot heat transfer fluid reservoir, and the compressor heat transfer fluid is circulated back to a reservoir that is the same as or different from the hot heat transfer fluid reservoir, or is circulated into the at least one compressor, the compressed working fluid discharged from the at least one compressor is received in the evaporator to undergo evaporation, and the evaporated working fluid discharged from the at least one evaporator is directed back to the at least one compressor.

8. The system according to claim 7 includes at least one second counter-flow heat exchanger, which is arranged between the at least one compressor and the at least one evaporator in the second flow path and is configured to perform heat exchange between the working fluid leaving the at least one compressor and the working fluid leaving the at least one evaporator.

9. The system according to claim 8, wherein: The heat exchanger is configured to increase the temperature of a working fluid flowing from the compressor to the turbine.

10. The system of any one of claims 7 to 9, comprising at least one second separation zone disposed in the at least one turbine, the second separation zone being configured to separate between a heat transfer fluid and a working fluid.

11. The system according to any one of claims 7 to 10, comprising at least one pressure reducing nozzle, which is arranged between at least one second heat exchanger and the at least one evaporator in the second flow path to reduce the pressure and temperature of the working fluid flowing from the at least one second heat exchanger to the at least one evaporator.

12. The system according to any one of claims 1 to 11, wherein: The working fluid is a liquid / vapor phase change (LVPhC) working fluid selected to be: (i) in vapor phase upon (1) entering the at least one compressor, (2) in temperature equilibrium after mixing with the heat transfer fluid in the at least one turbine, and (3) leaving the at least one evaporator; and (ii) in liquid phase upon (4) leaving the at least one condenser and (5) leaving the at least one compressor.

13. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising: at least one hot heat transfer fluid reservoir, the at least one hot heat transfer fluid reservoir containing a hot heat transfer fluid; at least one two-phase turbine and at least one two-phase compressor, said at least one two-phase compressor being configured to compress a compressor heat transfer fluid, i.e., a compressor heat transfer fluid, said compressor heat transfer fluid being the same as or different from said hot heat transfer fluid; The at least one hot heat transfer fluid reservoir is selectively (i) fluidically connectable to the at least one two-phase turbine in a discharge operating mode or (ii) fluidically connectable or thermally coupled to the at least one two-phase compressor in a charge operating mode for (1) supplying the hot heat transfer fluid to the corresponding turbine in the discharge operating mode or for (2) exchanging heat between the compressor heat transfer fluid and the hot heat transfer fluid; at least one condenser in fluid communication with the turbine for receiving a working fluid from the turbine and condensing the working fluid; at least one evaporator in fluid communication with the at least one compressor for receiving a working fluid from the at least one compressor and evaporating the working fluid, the at least one evaporator being the same or a different element from the at least one condenser; The discharge mode defines a first flow path for the working fluid, and the charge mode defines a second flow path for the working fluid; and wherein, in the energy release mode, the working fluid flows in the first flow path from the at least one first condenser to one or more nozzles within the at least one turbine, the nozzles being configured to cause rotation of the turbine when the fluid is discharged from the nozzles, thereby mixing the working fluid with the heat transfer fluid to form a heat transfer fluid / working fluid mixture in the one or more nozzles, in which the working fluid undergoes quasi-isothermal expansion, thereby accelerating the heat transfer fluid / working fluid mixture and causing the mixture to be discharged through the one or more nozzles while reducing the temperature of the heat transfer fluid, the heat transfer fluid / working fluid mixture discharged from the one or more nozzles being received in at least one first separation zone, the first separation zone being configured to separate the working fluid from the heat transfer fluid, the heat transfer fluid being recycled back to the at least one thermal reservoir or the one or more nozzles, and the separated working fluid flows into the condenser and is received in the condenser to undergo condensation in the condenser, the condensed working fluid discharged from the at least one condenser flows back to the turbine; and Wherein, in the charging mode, the working fluid flows in the second flow path, and the at least one compressor is configured to form a compressor heat transfer fluid / working fluid mixture, and quasi-isothermally compress the working fluid in the mixture along the compressor flow path, and thereby heat the compressor heat transfer fluid, the compressor heat transfer fluid is circulated back to a reservoir that is the same as or different from the heat transfer fluid reservoir or is circulated back to the at least one compressor, and the compressed working fluid discharged from the at least one compressor flows to be received in the evaporator to undergo evaporation, and the evaporated working fluid discharged from the at least one evaporator returns to the at least one compressor.

14. The system according to claim 13, wherein: The at least one evaporator and the at least one condenser are the same element.

15. The system according to claim 13 or 14 comprises at least one first counter-flow heat exchanger, which is arranged between the at least one turbine and the at least one condenser in the first flow path and is configured to perform heat exchange between the working fluid exiting from the at least one turbine and the working fluid exiting from the at least one condenser.

16. The system of claim 14, wherein: The heat exchanger is configured to reduce a temperature of a working fluid flowing from the turbine to the condenser.

17. The system according to any one of claims 13 to 16 comprises at least one second counter-flow heat exchanger, which is arranged in the second flow path between the at least one compressor and the at least one evaporator and is configured to perform heat exchange between the working fluid leaving the at least one compressor and the working fluid leaving the at least one evaporator.

18. The system according to claim 17, wherein: The heat exchanger is configured to increase the temperature of a working fluid flowing from the compressor to the turbine.

19. The system according to claim 17 or 18, comprising both the at least one first heat exchanger and the at least one second heat exchanger, wherein The at least one first counter-flow heat exchanger and the at least one second counter-flow heat exchanger are the same one or more elements selectively connectable to the at least one turbine or the at least one compressor in a respective discharging mode or charging mode.

20. The system of any one of claims 13 to 19, comprising at least one pressurizing arrangement configured to pressurize or advance the working fluid after it is condensed in the at least one condenser.

21. The system of claim 20, wherein: The arrangement comprises a pump.

22. The system of any one of claims 13 to 21, comprising at least one first separation zone disposed in the at least one turbine, the at least one first separation zone for separating between a working fluid and a heat transfer fluid.

23. The system of any one of claims 13 to 22, comprising at least one second separation zone disposed in the at least one compressor, the at least one second separation zone for separating between a working fluid and a heat transfer fluid.

24. The system according to any one of claims 13 to 23, comprising at least one pressure reducing nozzle, wherein the at least one pressure reducing nozzle is arranged between the at least one second heat exchanger and the at least one evaporator in the second flow path to reduce the pressure and temperature of the working fluid flowing from the at least one second heat exchanger to the at least one evaporator.

25. The system according to any one of claims 13 to 24, wherein: The working fluid is a liquid / vapor phase change (LVPhC) working fluid selected to be: (i) in vapor phase upon (1) entering the at least one compressor, (2) in temperature equilibrium after mixing with the heat transfer fluid in the at least one turbine, and (3) leaving the at least one evaporator; and (ii) in liquid phase upon (4) leaving the at least one condenser and (5) leaving the at least one compressor.

26. A system according to any one of claims 13 to 25, wherein: One or both of the at least one compressor and the at least one turbine are thermally insulated.

27. The system of any one of claims 13 to 26, comprising one or more selector valves for allowing the at least one hot heat transfer fluid reservoir to be selectively connected to the at least one compressor and the at least one turbine.

28. A system according to any one of claims 13 to 27, wherein The heat transfer fluid is selected from the list consisting of: antifreeze liquid, water, brine, thermal oil, molten salt, ethylene glycol, and a working fluid in liquid phase.

29. The system of any one of claims 13 to 28, wherein: The working fluid is selected from the list consisting of: air, nitrogen, hydrogen, CO2, ammonia, propane, ORC phase change material, pentane, refrigeration phase change material.

30. The system of any one of claims 13 to 29, comprising at least one external heat source allowing for controllable heating of the heat transfer fluid.

31. A system according to any one of claims 13 to 30, wherein: The at least one condenser and the at least one evaporator are configured to exchange heat with their surroundings for condensation and evaporation, respectively.

32. A system according to any one of claims 13 to 31, wherein The at least one evaporator is configured to be heated by at least one external heat source in the charging mode of operation.

33. The system of claim 32, comprising an insulated enclosure including the at least one condenser or the at least one evaporator configured for heat input from an external heat source and for controlled release of excess heat.

34. A system according to any one of claims 13 to 33, wherein: The at least one first counter-flow heat exchanger and the at least one second counter-flow heat exchanger are regenerators.

35. The system of any one of claims 13 to 34, wherein: The inlet compressor pressure of the working fluid and the pressure of the working fluid in the evaporator are below the critical pressure at a temperature lower than the ambient temperature, thereby allowing the working fluid to evaporate and heat to flow from the ambient to the working fluid vapor.

36. A system according to any one of claims 13 to 35, wherein: The at least one first heat exchanger comprises at least one first thermal pendulum.

37. The system of claim 36, wherein: Each of the at least one first heat exchanger includes a first heat exchanger section, a second heat exchanger section, and a first thermal pendulum section; wherein a flow path of a working fluid between the first heat exchanger section and the second heat exchanger section is through the thermal pendulum.

38. A system according to any one of claims 13 to 37, wherein: The second heat exchanger includes a second thermal pendulum.

39. The system of claim 38, wherein: Each of the at least one second heat exchanger includes a first heat exchanger section, a second heat exchanger section, and a second thermal pendulum section; wherein a flow path of the working fluid between the first heat exchanger section and the second heat exchanger section is through the second thermal pendulum.

40. The system according to any one of claims 38 and 39, wherein The second thermal pendulum is identical to the first thermal pendulum.

41. A system according to any one of claims 13 to 40, wherein: The heat pendulum has a heat capacity greater than the heat capacity of the working fluid in its liquid phase, and the heat pendulum is configured to exchange heat with the working fluid passing through the heat pendulum to compensate for inefficient heat exchange between the liquid phase of the working fluid and the gas phase of the working fluid, so that (1) in the charging operating mode, the heat pendulum is heated while cooling the liquid before the liquid enters the turbine, and (2) in the discharging operating mode, the heat pendulum is cooled while heating the liquid before the liquid enters the turbine.

42. A system according to any one of claims 13 to 41, wherein The first flow path and the second flow path are closed-loop flow paths.

43. A system according to any one of claims 13 to 42, wherein: The at least one turbine is configured to increase the pressure of the heat transfer fluid to obtain a high-pressure heat transfer fluid, and introduce the high-pressure heat transfer fluid into the one or more nozzles so that the high-pressure heat transfer fluid is mixed with the working fluid at approximately the same pressure, thereby forming a heat transfer fluid / working fluid mixture, wherein the working fluid is then quasi-isothermally expanded within the one or more nozzles, thereby accelerating the heat transfer fluid / working fluid mixture toward the outlet of the one or more nozzles.

44. A system according to any one of claims 13 to 43, wherein At least one of the compressors includes a heat transfer fluid pump for increasing the pressure of the heat transfer fluid, the heat transfer fluid pump being fluidically connected to a compressor nozzle, the compressor nozzle being configured to receive pressurized heat transfer fluid from the heat transfer fluid pump and to mix the pressurized heat transfer fluid with a working fluid to obtain a heat transfer fluid / working fluid mixture within the nozzle, the heat transfer fluid / working fluid mixture being discharged from the nozzle at a pressure higher than the pressure of the working fluid introduced into the compressor.

45. The system of any one of claims 13 to 44, wherein: The at least one working fluid pump is included within the at least one condenser.

46. A system according to any one of claims 1 to 45, wherein The evaporator is kept at a temperature above ambient.

47. A system according to any one of claims 1 to 46, wherein: The compressor heat transfer fluid is different from the hot heat transfer fluid and flows in a closed loop in the compressor and exchanges heat with the hot heat transfer fluid reservoir in a charging mode.

48. A system according to any one of claims 1 to 46, wherein: The compressor heat transfer fluid is the same as the hot heat transfer fluid, and the compressor heat transfer fluid reservoir is the same as the hot heat transfer fluid reservoir, and in charging mode, the hot heat transfer fluid reservoir is connected to the at least one two-phase compressor fluid for supplying the hot heat transfer fluid to the at least one compressor.

49. A system for storing and extracting energy in respective charging and discharging modes of operation, the system comprising: at least one two-phase turbine and at least one two-phase compressor; at least one hot heat transfer fluid reservoir containing a hot heat transfer fluid and at least one cold heat transfer fluid reservoir containing a cold heat transfer fluid, each of the at least one hot heat transfer fluid reservoir and the at least one cold heat transfer fluid reservoir being selectively fluidly connectable to the at least one compressor or the at least one turbine; at least one intermediate heat exchanger disposed in a flow path between the at least one compressor and the at least one turbine; wherein, in a charging mode, the at least one compressor is fluidly connected to the at least one hot heat transfer fluid reservoir to receive hot heat transfer fluid from the at least one hot heat transfer fluid reservoir, and the at least one compressor quasi-isothermally compresses a working fluid (WF) mixed with the hot heat transfer fluid, such that the compressed working fluid flows through at least one first heat exchanger to reduce the temperature of the compressed working fluid, and then mixes with cold heat transfer fluid in one or more nozzles of a turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the heat transfer fluid and working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the turbine is directed toward the at least one first heat exchanger to be heated for use in another cycle; Wherein, in the energy release mode, the at least one compressor is configured to receive cold heat transfer fluid from a cold heat transfer fluid reservoir and quasi-isothermally compress the working fluid mixed in the cold heat transfer fluid, so that the compressed working fluid flows through the at least one first heat exchanger to increase the temperature of the compressed working fluid, and then mixes with the hot heat transfer fluid in the one or more nozzles of the turbine to undergo isothermal or quasi-isothermal expansion, which accelerates the heat transfer fluid / working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for another cycle.

50. A system for storing and extracting energy in respective charging and discharging modes, the system comprising: at least one two-phase turbine and at least one two-phase compressor; at least one hot heat transfer fluid reservoir containing a hot heat transfer fluid and at least one cold heat transfer fluid reservoir containing a cold heat transfer fluid, each of the at least one hot heat transfer fluid reservoir and the at least one cold heat transfer fluid reservoir being selectively connectable to the at least one compressor / condenser or the at least one turbine; at least one intermediate exchanger disposed in the flow path between the at least one compressor and the at least one turbine; wherein, in a charging mode, the at least one compressor / condenser is fluidly connected to the at least one hot heat transfer fluid reservoir to receive hot heat transfer fluid from the at least one hot heat transfer fluid reservoir, and the at least one compressor / condenser quasi-isothermally compresses a working fluid in a liquid / vapor phase change working fluid (LVPhC) mixed with the hot heat transfer fluid and quasi-isothermally condenses the working fluid, so that the condensed liquid / vapor phase change working fluid flows through at least one first heat exchanger to reduce the temperature of the condensed liquid / vapor phase change working fluid, and then mixes with cold heat transfer fluid in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the heat transfer fluid and evaporated liquid / vapor phase change working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the evaporated liquid / vapor phase change working fluid discharged from the turbine is directed toward the at least one first heat exchanger to be heated for another cycle; Wherein, in the energy release mode, the at least one compressor is configured to receive cold heat transfer fluid from the cold heat transfer fluid reservoir, and quasi-isothermally condense the liquid / vapor phase change working fluid mixed in the cold heat transfer fluid and quasi-isothermally compress the liquid / vapor phase change working fluid, so that the condensed liquid / vapor phase change working fluid flows through the at least one first heat exchanger to increase the temperature of the condensed liquid / vapor phase change working fluid, and then mixes with the hot heat transfer fluid in the one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion, which accelerates the heat transfer fluid and liquid / vapor phase change working fluid mixture to generate kinetic energy that can be converted into electrical energy, and the liquid / vapor phase change working fluid discharged from the at least one turbine is directed toward the at least one first heat exchanger to be cooled for another cycle.

51. A system for converting electrical energy into heat and extracting stored heat as electrical energy, the system comprising: The system according to any one of claims 1 to 50, at least one generator rotationally coupled to the at least one turbine for generating electricity in the discharge mode of operation, and At least one electric motor is rotationally coupled to the at least one compressor for operating the compressor to charge the at least one thermal reservoir.

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