Thermal Energy Storage System

Abstract

A system that allows for efficient heat pumping, storage of thermal energy, and recovery of the stored thermal energy into electricity on demand. The system operates in two modes of operation: a charge mode in which thermal energy is input into an electrically driven compressor and transferred by a heat transfer fluid to a high temperature heat transfer fluid reservoir, and a discharge mode in which thermal energy from the high temperature reservoir is harnessed in a turbine to generate kinetic energy that can be used directly or converted to electrical energy for use as desired.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure is in the field of thermal-based storage systems to enable the recovery of electrical energy and the controllable use of this energy. [Background technology]

[0002] Prior art heat engines include the Carnot-Stirling and Ericsson thermodynamic cycles, all of which reach the Carnot efficiency limit through an isothermal process when converting heat to work (electricity). Traditionally, heat cycles include a compressor and a turbine based on adiabatic processes, such as those in Rankine and Brayton. In the reverse process, a 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 stored heat and reused as electricity again. As far as we know, all implementations of the Carnot cell have limited efficiency. Below is an example of a charge-discharge Brayton cycle (see also Figure 1). The system includes high-temperature (H-HEX) and low-temperature (C-HEX) thermal reservoirs along with a heat exchanger, compressor, and turbine. The entire system is thermally insulated. During the charging process, electricity drives the compressor, which compresses gas and raises its temperature. This heat is stored in the H-HEX. The compressed air is cooled in the heat exchanger and reaches the turbine to discharge pressure. The turbine's power is returned to the compressor. The exit gas is cold and passes through the C-HEX to lower the temperature of the cold reservoir. The gas then goes to the compressor for an additional cycle. The charging process results in a temperature change between the two thermal reservoirs. During the discharging process, cold air from the cold reservoir is compressed and heated, passing through the hot reservoir, increasing its temperature (the reservoir is cooled). The compressed hot gas then reaches the turbine, generating power to drive the compressor and generate output power. After the turbine, the cold gas reaches the 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 the large size and cost of the device due to the poor thermal energy density. The heat exchanger is expensive. The expansion and compression are adiabatic, resulting in inefficiency due to temperature overshoot relative to the reservoir temperature. Additionally, additional low-quality waste heat is inefficient in increasing round-trip efficiency due to the high operating temperatures.

[0003] References that may be relevant as background to the subject matter of this disclosure are as follows: WO2022 / 049573 WO2022 / 234554

[0004] Acknowledgment of the above references herein should not be inferred as meaning that they are in any way relevant to the patentability of the subject matter of this disclosure. Summary of the Invention

[0005] The present disclosure provides a system for enabling efficient heat pumping, storage of thermal energy, and recovery of this stored thermal energy into electricity on demand. Thus, the system operates in two modes: (1) a charge mode of operation in which thermal energy is input into an electrically driven compressor and transferred by a heat transfer liquid (HTL) to a high-temperature heat transfer liquid reservoir (which may also be referred to herein for short as a "high-temperature reservoir"), and (2) a discharge mode of operation in which thermal energy from the high-temperature reservoir is utilized in a turbine to generate kinetic energy that can be used directly or converted to electrical energy for use as desired. In addition to its use as a carrier of thermal energy, the HTL also actively participates in the compression process in the compressor during the system's charge mode and in the expansion process that occurs in the turbine during the system's discharge mode. The high temperature reservoir has a temperature greater than ambient temperature, typically significantly greater than ambient temperature, e.g., 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 more. The extent of heating of the high temperature reservoir during energy charging and the extent of cooling of the high temperature reservoir during energy discharging depend, inter alia, on the heat capacity of the high temperature reservoir.

[0006] In some aspects and embodiments of the present disclosure, a low-temperature HTL reservoir (which may also be referred to herein for short as a "low-temperature reservoir") is also used, and heat is pumped from the low-temperature reservoir to the high-temperature reservoir or released from the high-temperature reservoir to the low-temperature reservoir during heat storage and utilization, respectively. The low-temperature reservoir has a temperature lower than ambient temperature, typically significantly lower than ambient temperature, e.g., 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 more. The degree of cooling of the low-temperature reservoir during energy storage and the degree of heating of the low-temperature reservoir during energy discharge depend, inter alia, on the heat capacity of the high-temperature reservoir.

[0007] The high-temperature and low-temperature reservoirs may be thermally insulated according to some embodiments of the present disclosure. Both the compression and expansion processes involve mixing the working fluid (WF) flowing through the system with the HTL to form a two-phase mixture of WF and HTL (which may be referred to herein as an "HTL / WF mixture"). In the compressor, the WF joins the mixture in gaseous form (terms such as "gas," "gaseous," and the like encompass gas and vapor herein) and is compressed, while in the turbine, the WF enters the mixture as compressed gas or in liquid phase and is optionally further compressed within the mixture. In the HTL / WF mixture, the HTL is typically the more abundant component. At the time of, or shortly after, the formation of the HTL / WF mixture, the temperatures of the HTL and WF are approximately equal, due to the HTL cooling or heating the WF during the compression or expansion of the WF, respectively. It should be noted that the heat capacity of the HTL is much greater than that of gaseous WF (the HTL may have a heat capacity approximately three orders of magnitude greater than that of gaseous WF). Thus, the WF is brought to the temperature of the HTL, and expansion in the turbine or compression in the compressor occurs with essentially no change in temperature. 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 were measured very accurately during the process, only small temperature changes would be recorded due to the enormous heat capacity of the HTL). The temperature at the end of expansion or compression of the WF during a quasi-isothermal process is less than 20%, 10%, 5%, 4%, 3%, 2%, or 1% Kelvin from the initial temperature of the WF.

[0008] Thus, during the compression process, the HTL constantly cools the WF in the HTL / WF mixture, and heat transfer from the WF to the HTL results in the aforementioned quasi-isothermal compression of the WF in the HTL / WF mixture. By the end of the compression process, the WF can be in either a gas 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 operating on a mixture of one liquid-phase material, i.e., the HTL, and another gas-phase material, i.e., the WF.

[0009] Similarly, during the expansion process in the turbine, the HTL constantly heats the WF in the HTL / WF mixture, resulting in 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, by one of the separation methods described above. Thus, similar to the definitions of a compressor and a two-phase compressor, the turbine of this disclosure is a two-phase turbine.

[0010] In some embodiments, and as further described below, the HTL and WF may be the same material in different phases, particularly in the compressor. According to one embodiment, the compressor has its own HTL, referred to throughout this application as the compressor HTL, flowing in a closed loop within the compressor, and the WF mixed with the compressor HTL may be the same material in different phases. During the compression process in the compressor, the pressure of the compressor HTL drops so quickly that the compressor HTL cannot change phase to gas, but the WF mixed with the compressor HTL can be drawn in gas phase. Thus, the WF and the compressor HTL may be the same material but in different phases during the compression process in the compressor. If the compressor has its own compressor HTL that is different from the high-temperature HTL, the compressor HTL heats up during the compression process and then transfers heat to the high-temperature HTL reservoir via any suitable thermal coupling.

[0011] In some other embodiments, the compressor is supplied with HTL from a high-temperature HTL reservoir. Thus, in these embodiments, the high-temperature HTL is cycled between the high-temperature HTL reservoir and the compressor, heating the high-temperature HTL reservoir with each cycle.

[0012] In some embodiments of the disclosed system, the flow paths for the HTL and WF may be the same in the two operating modes. In other embodiments of the disclosed system, the flow paths for the HTL and WF may be the same but with opposite flow directions. In still other embodiments of the disclosed system, different flow paths exist for the HTL and WF in the two operating modes of the disclosed system: (1) a charge mode in which the HTL is circulated between the high-temperature reservoir and the compressor and the WF is circulated between the compressor and the evaporator; and (2) a discharge mode in which the HTL is circulated between the high-temperature reservoir and the turbine and the WF is circulated between the turbine and the condenser. In some embodiments, the same flow paths are used in the two operating modes but with opposite flow directions.

[0013] The present disclosure provides three system embodiments, hereinafter referred to as a "first system embodiment," a "second system embodiment," and a "third system embodiment." The systems of the second and third system embodiments also include a low-temperature reservoir, while the system of the first system embodiment does not include such a reservoir. In the system of the first system embodiment, heat may be exchanged with the environment or an external medium (e.g., a body of water) via a WF, and heat is absorbed from the environment or external medium in a charging mode of operation and vice versa in a discharging mode of operation. In the systems of the second and third system embodiments, heat is input between a low-temperature reservoir and a high-temperature reservoir via a WF in a charging mode of operation and vice versa in a discharging mode of operation.

[0014] The second and third system embodiments differ in that in the third system embodiment the WF is a liquid / vapor phase change (LVPhC).

[0015] A first system embodiment provides a system for storing and recovering electrical energy. The system includes a two-phase turbine and a two-phase compressor. The compressor is configured to compress a high-temperature HTL. The high-temperature HTL may be the same as or different from the high-temperature HTL. The system may also include a high-temperature HTL reservoir, which may be configured as an element within the compressor that stores the high-temperature HTL before and / or after the compression process in the compressor, or which may be a separate element fluidly coupled to the compressor, configured to replenish the high-temperature HTL consumed during operation of the compressor, for example.

[0016] The system of the first system aspect also includes a high-temperature HTL reservoir containing a high-temperature HTL. The HTL can be any material (which may itself be a mixture) that remains in a liquid phase throughout the entire operating temperature and pressure range of the system. As described above, in some embodiments, the HTL can be the same material as the WF, but remains in a liquid phase due to a short-term pressure drop in the compressor. The high-temperature HTL reservoir is configured to receive or release the high-temperature HTL during the respective charge and discharge modes of operation and may comprise a material other than the HTL, such as stone or gravel, that can receive and store thermal energy transferred from the HTL. The high-temperature HTL reservoir can be selectively fluidly connected to a quasi-isothermal two-phase turbine or a quasi-isothermal two-phase compressor, or in some embodiments, thermally coupled only to a two-phase compressor, which is a thermally isolated two-phase compressor, to supply the high-temperature HTL to the respective turbine or compressor during the respective discharge or charge modes of operation or to enable heat exchange between the compressor HTL and the high-temperature HTL reservoir. In other words, the system is configured to connect the high temperature HTL reservoir to the compressor in charge mode and to the turbine in discharge mode.

[0017] The compressor and turbine are typically thermally insulated.

[0018] Reference to an element herein should be understood to mean the presence of at least one such element. In other words, the terms "a," "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, a system of the present disclosure may include one heat exchanger unit or multiple such units. The same applies to, for example, a condenser, evaporator, reservoir, and all other described elements. For ease of explanation, reference is made to one such element, e.g., a turbine, compressor, heat exchanger, condenser, evaporator, reservoir, etc., with the understanding that this should be read 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. When a system of the present disclosure includes multiple defined elements, the multiple such elements may operate in series or parallel, as the case may be.

[0019] The system of the first system embodiment further includes a condenser in fluid communication with the turbine to receive and condense the WF flowing from the turbine, i.e., in the discharge mode of the system, the condenser is downstream of the turbine in the flow path of the WF.

[0020] The system of the first system embodiment optionally further includes a working fluid pump (WF pump) in fluid communication with the condenser for pressurizing the condensed WF condensed in the condenser. The WF pump may be located at various positions in the WF flow path, for example, within the condenser so as to be an integral part of the condenser, or in the flow path between the condenser and the first heat exchanger or between the first heat exchanger and the turbine.

[0021] According to some embodiments, the system of the first system aspect further includes an evaporator in fluid communication with the compressor for receiving and evaporating the WF flowing from the compressor. The evaporator may be the same or a different element from the condenser. That is, in the charging mode of operation of the system, the evaporator is downstream of the compressor in the WF flow path. In some embodiments, the condenser and evaporator are the same element. The condenser / evaporator may be configured to allow heat exchange between the WF flowing therethrough and the ambient.

[0022] The discharge mode of the system defines a first flow path for the WF, and the charge mode defines a second flow path for the WF. In some embodiments, elements that make up the first WF flow path serve a dual role 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 may be dual-used in both the first and second flow paths (sometimes in opposing WF flows). This may also be true for other elements, such as first and second countercurrent heat exchangers, which may be the same element used in both flow paths as defined below, or condensers that may be configured to also serve as evaporators in opposing WF flow paths.

[0023] According to some embodiments of the system of the first system aspect, the system includes a first countercurrent heat exchanger, typically a recuperator, disposed between the turbine and the condenser in the first flow path and configured for heat exchange between the WF exiting the turbine and the WF exiting the condenser.

[0024] According to some embodiments of the system of the first system aspect, the system includes a second countercurrent heat exchanger, typically a recuperator, disposed between the compressor and the evaporator in the second flow path and configured for heat exchange between the WF exiting the compressor and the WF exiting the evaporator, which may be the same or a different element as the first heat exchanger.

[0025] The flow path of the WF in the discharge and charge modes of operation of the first system embodiment is described below.

[0026] In a discharge mode, according to one embodiment of the first system aspect of the present disclosure, the WF flows through one or more nozzles in the turbine in a first flow path, where the WF mixes with the HTL to form an HTL / WF mixture. This flow may pass through a first heat exchanger. The WF may be LVPhC WF. The HTL / WF mixture undergoes quasi-isothermal expansion in one or more nozzles, i.e., expansion in which the WF is maintained at approximately the same temperature by heat exchange with the HTL, which has a much larger heat capacity. In other words, cooling of the WF during the expansion process has only a small effect on the temperature of the HTL / WF mixture. This quasi-isothermal expansion accelerates the HTL / WF mixture, which is then discharged through one or more nozzles. The kinetic energy discharged through the nozzles reduces the temperature of the HTL while inducing the rotation of the turbine, which converts this work into electrical power (generated by a generator rotatably coupled to the turbine) that can be stored or immediately utilized. The HTL / WF mixture discharged from the nozzle may be received in an optional first separation zone configured to separate the WF from the HTL. The separated HTL may be recycled to the high-temperature reservoir or one or more nozzles (these processes typically occur in parallel, with some of the HTL being recycled to the high-temperature reservoir, while another portion of the high-temperature HTL is instead discharged from the reservoir, and the remaining portion continues circulating to one or more nozzles). The separated WF may optionally be directed to flow through a first heat exchanger to reduce its temperature and then received in a condenser to undergo condensation. The condensed WF discharged from the condenser may be driven by a pressurizing configuration configured to pressurize or propel the WF, such as a configuration including a WF pump configured to return the WF to the turbine at high pressure. Typically, the WF passes through the optional first heat exchanger and may be heated by the counterflow WF (cooled during passage through the heat exchanger as described above) flowing from the turbine to the condenser. The above configuration may pressurize the WF to turbine operating pressure. The above arrangement can be located 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 pump arrangement is constituted by a turbine, i.e., the centrifugal force of the turbine sends the WF back to the turbine at high pressure.

[0027] The turbine may have a plurality of nozzles fixedly coupled to the shaft of the turbine such that kinetic energy is generated to induce rotation of the shaft. The nozzles may be located on dedicated elements extending radially from the shaft or on the rotating blades of the turbine.

[0028] In a charging mode of operation, according to one embodiment of the first system aspect of the present disclosure, the WF flows through the second flow path, and the compressor is configured to receive high-temperature HTL from a high-temperature reservoir and WF vapor, e.g., passing through a second heat exchanger, to form a HTL / WF mixture. The WF in this mixture is typically compressed quasi-isothermally and optionally (if it is an LVPhC) condensed along a compressor flow path that co-flows the WF and HTL through a nozzle configured to enable quasi-isothermal compression, i.e., compression in which the WF is maintained at approximately the same temperature by heat exchange with the HTL, which has a much larger heat capacity. In other words, heating of the WF in the compression process has a negligible effect on the temperature of the HTL / WF mixture. The HTL / WF mixture can be separated in an optional second separation zone. The separated HTL is circulated to the high-temperature reservoir or the compressor (these typically occur in parallel, with some of the HTL being recirculated to the high-temperature reservoir, while another portion of the high-temperature HTL is forced into the compressor, and the remaining portion continues circulating in the compressor). The compressed WF is discharged from the compressor and flows, for example through a second heat exchanger to lower its temperature, to the evaporator for evaporation, optionally flash evaporation, where it is cooled to a refrigeration temperature below ambient temperature. The refrigeration temperature is set by the inlet pressure to the compressor. Optionally, only a portion of the WF evaporates. After evaporation, the vapor can be further heated by the environment to reach complete evaporation at ambient temperature. The evaporated WF discharged from the evaporator is directed through an optional second heat exchanger to be heated and returns to the compressor for another cycle via heat exchange with the countercurrent WF flowing from the compressor to the evaporator (which is cooled during passage through the heat exchanger as described above). Optionally, complete evaporation is reached only after a recuperator. The compressor may be powered by a rotatably coupled electric motor to store the generated electrical energy or access electrical energy in the electrical grid for later use, such as during peak demand for grid energy.

[0029] In some embodiments of the first system aspect, both the discharging and charging modes of operation are according to the embodiments described above.

[0030] Thus, the system of the first system embodiment can be switched between two operating modes: discharge mode and charge mode. In discharge mode, HTL from the high-temperature HTL reservoir is circulated between the reservoir and the turbine, utilizing heat delivered by the HTL stored in the high-temperature HTL reservoir, whose temperature decreases throughout this process. In discharge mode, the WF flows through various elements in the following order (the starting point in the following description is arbitrary because the WF is intentionally circulated within the process), is received by the turbine, then flows in one direction through the first heat exchanger to the condenser, and then flows countercurrently from the condenser to the first heat exchanger and back to the turbine; this flow from the condenser to the turbine is driven by a WF pump. In charge mode, the HTL from the high-temperature HTL reservoir is circulated between the reservoir and the compressor, or, if the compressor has its own compressor HTL, is thermally coupled to the compressor HTL, increasing its temperature with each cycle. In charging mode, the WF flows through the following flow path in the following order (again, the starting point in the following description is arbitrary as the WF is intentionally circulated in the process), is received by the compressor, then flows unidirectionally through a second heat exchanger to the evaporator, and then flows counter-currently from the evaporator through the second heat exchanger back to the compressor.

[0031] A second system embodiment of the present disclosure provides a system for storing heat and recovering electrical energy comprising a two-phase turbine and a two-phase compressor. The second system embodiment also comprises a high-temperature HTL reservoir containing a high-temperature HTL and a low-temperature HTL reservoir containing a low-temperature HTL, each selectively connectable to a quasi-isothermal thermally insulated compressor / condenser or a quasi-isothermal thermally insulated turbine, depending on the operating mode of the system.

[0032] The two-phase compressor may include a compressor HTL for compressing operation and a compressor HTL reservoir for holding the compressor HTL. The compressor HTL may be the same as the high-temperature and low-temperature HTL, and the compressor HTL reservoir may be the same as the high-temperature and low-temperature HTL reservoirs, with the high-temperature HTL reservoir fluidly coupled to the compressor to supply the high-temperature HTL in a charge mode and the low-temperature HTL reservoir fluidly coupled to the compressor to supply the low-temperature HTL in a discharge mode. Alternatively, the compressor HTL and compressor HTL reservoir may be different from the high-temperature HTL and high-temperature HTL reservoir, respectively, and the compressor HTL flows through a flow path that allows it to thermally exchange heat with the high-temperature HTL reservoir to heat the high-temperature HTL reservoir in a charge mode and cool the low-temperature HTL reservoir in a discharge mode.

[0033] The high-temperature HTL is defined by a higher temperature than the low-temperature HTL. The high-temperature HTL can be used (i) in a charge mode to compress the mixed WF in the compressor while gradually heating during the quasi-isothermal compression of the WF in the compressor, thereby gradually increasing the temperature of the high-temperature reservoir to the same extent, and (ii) in a discharge mode to operate the turbine, i.e., to participate in the quasi-isothermal expansion of the HTL / working fluid mixture and utilize the heat stored in the high-temperature reservoir that is gradually reduced in this process. The low-temperature HTL can be used (i) in a discharge mode to condense and compress the WF in the compressor, and (ii) in a charge mode to participate in the quasi-isothermal expansion of the HTL / WF mixture and heat up in this process. Therefore, the minimum temperature of the low-temperature HTL must be above the boiling temperature of the working fluid at the initial pressure in the turbine. The high-temperature HTL can be made of the same material as the low-temperature HTL or a different material.

[0034] In the charge mode of operation of the system of the second system embodiment, heat flows from the cold reservoir to the hot reservoir via the WF, cooling the former and heating the latter in the process via input electrical energy to the compressor. In the discharge mode of operation of the system, heat flows from the hot reservoir to the cold reservoir via the WF, cooling the former and heating the latter, and this energy flow is converted to electrical energy by the turbine.

[0035] The system of the second system embodiment further includes an intermediate heat exchanger disposed in the flow path between the compressor and the turbine.

[0036] In the charging mode of operation of the system of the second system embodiment, the compressor / condenser, powered by an electric motor that receives energy from external sources, typically from an external source, such as an access electrical input from the grid during periods of low electrical usage or generated electrical energy that cannot be directed to the grid during production, receives high-temperature HTL from the high-temperature HTL reservoir and quasi-isothermally compresses and condenses the LVPhC WF mixed with the high-temperature HTL. This compression gradually heats the high-temperature HTL throughout the charging process. The HTL / WF mixture is separated, and the high-temperature HTL is either directed to the HTL reservoir or recycled for continued use in the compressor (as noted above, these typically occur in parallel, with a portion of the HTL being recycled to the high-temperature reservoir while another portion of the HTL is sent into the compressor and continues to circulate within the compressor). The compressed and condensed WF discharged from the compressor / condenser flows through one flow path through a first heat exchanger to reduce its temperature, and then, optionally, is mixed with cold HTL in one or more nozzles of the turbine, where it undergoes isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and evaporated WF, generating kinetic energy in a manner similar to that described above. This kinetic energy can be converted to electrical energy by a generator rotatably coupled to the turbine and used to provide auxiliary power to the compressor. Optionally, the cold liquid WF is partially flash-evaporated without a turbine and then completely evaporated in the evaporator by extracting heat from the environment. The evaporated WF discharged from the turbine or evaporator is directed to the first heat exchanger, where it is heated by passing through the opposite flow path (the compressed and condensed WF is cooled in the process), and then received by the compressor for another cycle.

[0037] In the discharge mode of operation of the system of the second system embodiment, the compressor (powered by a portion of the energy generated by the turbine, as described below) is optionally configured to receive low-temperature HTL from the low-temperature HTL reservoir and quasi-isothermally condense and compress the LVPhC WF mixed with the low-temperature HTL. This compression gradually heats the low-temperature HTL throughout the charging process. The HTL / WF mixture is separated, and the high-temperature HTL is either directed to the HTL reservoir or recycled for continued use in the compressor (as described above, these typically occur in parallel, with a portion of the HTL recycled to the high-temperature reservoir while another portion of the HTL is sent into the compressor and another portion continues to circulate in the compressor). Optionally, the WF is condensed in a condenser that condenses the WF. The condensed WF discharged from the compressor or condenser flows unidirectionally through a first heat exchanger to increase its temperature, then flows to a turbine where it mixes with the hot HTL in the turbine nozzle, vaporizes, and undergoes quasi-isothermal expansion, accelerating the HTL and WF mixture and generating kinetic energy that can be converted to electrical energy. The WF discharged from the turbine is directed to the first heat exchanger and flows in a counter-flow path to be cooled (the condensed WF is heated in the process) before being received by the compressor or condenser for another cycle.

[0038] It should be noted that in an embodiment in which the compressor has its own compressor HTL, the compressor is only thermally coupled to the high-temperature and low-temperature HTL reservoirs, and the high-temperature and low-temperature HTLs are not involved in the compression process in the compressor. In this embodiment, the only HTL involved in the compression process is the compressor HTL, and the flow path of the compressor HTL is designed to exchange heat with the high-temperature and low-temperature HTL reservoirs in charge and discharge modes, respectively.

[0039] The system according to the third system embodiment has most of the same elements as the second system embodiment, with the main difference being that the WF is an LVPhC WF.

[0040] A system of a third system embodiment for storing and recovering energy in respective charge and discharge modes of operation includes a two-phase turbine and a two-phase compressor, a high-temperature HTL reservoir including a high-temperature HTL and a low-temperature HTL reservoir including a low-temperature HTL, each of which is selectively connectable to the compressor / condenser or the turbine, and an intermediate exchanger disposed in a flow path between the compressor and the turbine. The two-phase compressor may include a compressor HTL for compression operation and a compressor HTL reservoir including the compressor HTL. The compressor HTL may be the same as the high-temperature and low-temperature HTL, and the compressor HTL reservoir may be the same as the high-temperature and low-temperature HTL reservoirs, with the high-temperature HTL reservoir fluidly coupled to the compressor to supply the high-temperature HTL in a charge mode and the low-temperature HTL reservoir fluidly coupled to the compressor to supply the low-temperature HTL in a discharge mode, or the compressor HTL and compressor HTL reservoir may be different from the high-temperature HTL and high-temperature HTL reservoir, respectively, with the compressor HTL flowing through a flow path that allows it to thermally exchange heat with the high-temperature HTL reservoir to heat the high-temperature HTL reservoir in a charge mode and to cool the low-temperature HTL reservoir in a discharge mode.

[0041] In the charging mode, the compressor / condenser is fluidly connected to the high-temperature HTL reservoir and configured to receive the high-temperature HTL therefrom and quasi-isothermally compress and condense a liquid-to-vapor phase-change working fluid (LVPhC) WF mixed with the high-temperature HTL. The condensed LVPhC flows through a first heat exchanger to reduce its temperature, then mixes with the low-temperature HTL in one or more nozzles of the turbine to vaporize it and undergoes isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and vaporized LVPhC and generate kinetic energy that can be converted to electrical energy. The vaporized LVPhC discharged from the turbine is directed to an intermediate heat exchanger to be heated for another cycle.

[0042] In the discharge mode, the compressor receives low-temperature HTL from the low-temperature HTL reservoir and quasi-isothermally condenses and compresses LVPhC mixed with the low-temperature HTL. The condensed LVPhC flows through an intermediate heat exchanger to increase its temperature and is then mixed with the high-temperature HTL in one or more nozzles of the turbine. In the nozzles, the mixture vaporizes and undergoes quasi-isothermal expansion, accelerating the mixture of HTL and LVPhC and generating kinetic energy that can be converted into electrical energy. The LVPhC discharged from the turbine is directed to the first heat exchanger and cooled for another cycle.

[0043] It should be noted that in an embodiment in which the compressor has its own compressor HTL, the compressor is only thermally coupled to the high-temperature and low-temperature HTL reservoirs, and the high-temperature and low-temperature HTLs are not involved in the compression process in the compressor. In this embodiment, the only HTL involved in the compression process is the compressor HTL, and the flow path of the compressor HTL is designed to exchange heat with the high-temperature and low-temperature HTL reservoirs in charge and discharge modes, respectively.

[0044] Several embodiments of the present disclosure are described below. It should be noted that any combination of the embodiments described below is applicable to any system aspect of the present disclosure. 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 hereinafter to collectively refer to the systems of the first system aspect, the second system aspect, and the third system aspect.

[0045] 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 the surroundings, and depending on the WF temperature, pressure, and surroundings of the evaporator / condenser, the result is either evaporation of the WF or condensation of the WF. In some embodiments, complete evaporation in the evaporator is preceded by a partial flash evaporation of the liquid WF.

[0046] In some system embodiments, one heat exchanger is present in the system that operates in both the charge and discharge modes. For example, in a system of the first system embodiment, the first countercurrent heat exchanger and the second countercurrent heat exchanger are the same heat exchanger element. In a system of the first system embodiment having one heat exchanger, the heat exchanger is selectively connectable to the turbine or compressor in the respective discharge or charge modes of operation. However, two different heat exchanger elements, for example, one optimally configured for use in the discharge mode and the other optimally configured for use in the charge mode of operation, are also possible.

[0047] 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 (during operation in a charging process) to reduce the pressure and temperature of the WF flowing from the second heat exchanger to the evaporator, thereby increasing the temperature difference between the ambient temperature of the evaporator and the WF in the evaporator and enhancing heat transfer from the ambient temperature. It should be noted that in embodiments where (1) there is one common heat exchanger, (2) the evaporator is the same element as the condenser, or (3) both (1) and (2), the pressure reducing nozzle is selectively coupled to the second heat exchanger and the evaporator only in the charging mode and is disconnected in the discharging mode.

[0048] In some embodiments of the system, the pressure reducing nozzle is an orifice.

[0049] In some embodiments, the pressure reducing nozzle is a flash evaporation nozzle, which partially evaporates the WF and cools the WF temperature to below ambient temperature.

[0050] In some embodiments of the system, the WF is a liquid / vapor phase change (LVPhC) WF selected to be (i) in the vapor phase when it (1) enters the compressor, (2) when it is at temperature equilibrium after being mixed with the HTL in the turbine, and (3) when it exits the evaporator, and (ii) in the liquid phase when it (4) exits the condenser, and (5) when it exits the compressor.

[0051] In some embodiments of the system, either or both of the compressor and turbine are thermally isolated.

[0052] In some embodiments, the system further comprises one or more selector valves that allow for selective connection of the high temperature HTL reservoir to the compressor or the turbine.

[0053] In some embodiments, the system further comprises one or more selection valves that enable selective connection of the high temperature HTL reservoir to the compressor or turbine in respective charge and discharge modes, and selective connection of the low temperature HTL reservoir to the compressor or turbine in respective charge and discharge modes.

[0054] In some embodiments of the system, the HTL is selected from the list consisting of antifreeze, water, brine, thermal oil, molten salt, ethylene glycol, and WF in liquid phase.

[0055] In some embodiments of the system, the WF is selected from the list consisting of air, nitrogen, CO2, ammonia, propane, ORC phase change material, pentane, cyclopentane, and refrigeration phase change material. In some embodiments, the compressor HTL is the same material as the WF. Optionally, if the compressor HTL is different from the high-temperature HTL and flows in a closed loop within the compressor, the compressor HTL and the WF are the same material. To heat the high-temperature HTL reservoir, the compressor HTL flows along a flow path having a portion that allows heat exchange with the high-temperature HTL reservoir to transfer heat from the compressor HTL to the high-temperature HTL reservoir and thereby to the high-temperature HTL.

[0056] In some embodiments, the system further comprises an external heat source, e.g., from a waste energy source, combustion of gas or fossil fuels, that allows for controllable heating of the HTL. This is the case, for example, if the system is intended to be used as a standard heat engine, and the external heat source can be used to heat the HTL in the energy generation process, e.g., to heat an evaporator or to add heat via a special heating zone in the HTL flow path. This configuration can be used when the thermal energy within the system is depleted.

[0057] According to some embodiments of the present disclosure, external heat heats the WF in the evaporator to enhance evaporation or raise the evaporated WF to a temperature above ambient temperature, optionally reaching a pressure above ambient temperature, thereby reducing compressor power consumption. Optionally, the heat source for heating the evaporator is a waste heat source.

[0058] In some embodiments of the system, the external heat source is provided by the combustion of gas or fossil fuels that directly heats the HTL.

[0059] In some embodiments, the system further comprises an external heat source that allows for controllable heating of the high temperature reservoir.

[0060] In some embodiments of the system, the condenser and evaporator are configured to exchange heat with the surroundings for condensation and evaporation, respectively.

[0061] In some embodiments of the system, the evaporator is configured for heating by an external heat source, such as waste heat, during the charging mode of operation. The external heat source may be used to evaporate the working fluid and bring it to a desired temperature, which may improve the efficiency of the system. If the condenser and evaporator are the same element, the external heat source is thermally coupled to the condenser / evaporator only during the charging mode.

[0062] In some embodiments, the system further comprises a thermally insulated enclosure comprising the condenser and evaporator, the enclosure typically allowing controlled heat exchange with the surroundings, so the enclosure may comprise an inlet for receiving heat from an external heat source, for example in the form of exhaust gases or waste heat, and an outlet for controlled exhaust of excess heat and for allowing circulation of heat in and out of the enclosure.

[0063] In some embodiments of the system, the external heat source is waste heat, which may be at any temperature above ambient temperature.

[0064] In some embodiments of the system, the heat exchangers, including the first and second countercurrent heat exchangers of the first system embodiment and the intermediate heat exchangers of the second and third embodiments, are recuperators.

[0065] In some embodiments of the system, the system is configured such that the WF pressure at the inlet of the compressor and the pressure of the WF in the evaporator are approximately the same and are below the critical pressure at the critical point at temperatures below ambient temperature, thereby allowing evaporation of the WF and heat flow from the ambient to the WF vapor.

[0066] In some embodiments of the system, the first heat exchanger comprises a first heat pendulum.

[0067] In some embodiments of the system, the heat exchanger (including the first or second heat exchanger of the first system aspect and the intermediate heat exchanger of the second and third aspects) comprises a first heat exchanger section, a second heat exchanger section, and a first heat pendulum section, and the flow path of the WF between the first and second heat exchanger sections is through the heat pendulum.

[0068] In some embodiments of the system, the heat pendulum is designed to exchange heat only with the liquid phase WF flowing through the first heat exchanger.

[0069] In some embodiments of the system, the flow path of the WF is configured to flow sequentially from the first heat exchanger section to the heat pendulum and then to the second heat exchanger section, or from the second heat exchanger section to the heat pendulum and then to the first heat exchanger section, in different operating modes.

[0070] If the system comprises multiple heat exchangers, the heat pendulum, if present, and the overall design of the exchanger may be the same or different for all heat exchangers.

[0071] In some embodiments of the system, the thermal pendulum has a heat capacity value greater than the heat capacity of the WF in its liquid phase and is configured to exchange heat with the passing WF, i.e., the working fluid exiting either the first heat exchanger or the second heat exchanger, to compensate for inefficiencies in heat exchange between the liquid phase of the WF and the vapor phase of the WF, such that (1) in a charge mode of operation, the thermal pendulum heats up while cooling the liquid before it enters the turbine, and (2) in a discharge mode of operation, the thermal pendulum cools down while heating the liquid before it enters the turbine.

[0072] In some embodiments of the system, the flow path of the WF is a closed loop flow path, i.e., the WF flows within a closed system and is recirculated with each thermodynamic cycle of the system.

[0073] In some embodiments of the system, the turbine includes one or more nozzles configured to increase the pressure of the HTL received by the turbine to obtain high-pressure HTL, i.e., to a pressure higher than ambient or higher than the pressure of the HTL in the HTL hot reservoir, and introduce the high-pressure HTL into the one or more nozzles to mix with WF at approximately the same pressure to form an HTL / WF mixture, whereby quasi-isothermal expansion of the WF in the one or more nozzles allows acceleration of the HTL / WF mixture toward the outlet of the nozzle, and the kinetic energy of the HTL / WF mixture discharged from the outlet is used to generate energy.

[0074] The turbine may be either a reaction turbine or an impulse turbine.

[0075] In some embodiments of the system, the turbine includes an HTL pump configured to pressurize the HTL received in the turbine prior to introduction into the nozzle.

[0076] In some embodiments of the system, the turbine is a reaction turbine.

[0077] In some embodiments of the system, the first separation zone comprises a collection unit that allows collecting the discharged HTL separated from the WF and directing it either to a high-temperature HTL reservoir or to a nozzle of the turbine. For example, a portion of the HTL may be directed to the HTL reservoir and a portion of the HTL may be returned to the nozzle or to the HTL pump.

[0078] In some embodiments of the system, the turbine is a reaction turbine and the one or more nozzles are coupled to, attached to, or part of the reaction turbine.

[0079] In some embodiments, the collection unit defines a drain where the separated HTL accumulates, and the HTL is drawn from the drain into the nozzle by centrifugal force generated by a reaction turbine, which acts on the liquid in the nozzle and provides a driving force throughout the HTL column, creating suction. To maintain suction, some HTL must always be maintained in the HTL drain. This centrifugal force serves the function of an HTL pump. This propulsion of the HTL from the drain allows it to enter the nozzle at the nozzle's operating pressure, allowing for the desired quasi-isothermal expansion.

[0080] In some embodiments of the system, the first separation zone comprises a curved or circular frame onto which the mixture is discharged, the mixture engaging the curved or circular frame thereby resulting in a film flow on the surface of the curved or circular frame.

[0081] In some embodiments of the system, the compressor includes an HTL pump configured to increase the HTL pressure, the HTL pump fluidly coupled to a compressor nozzle configured to receive pressurized HTL from the HTL pump and mix with the WF in the nozzle to obtain an HTL / WF mixture, the nozzle designed to discharge the HTL / WF at a pressure higher than the pressure of the WF introduced into the compressor.

[0082] In some embodiments of the system, the condenser comprises the WF pump.

[0083] In some system embodiments, the compressor HTL, distinct from the high-temperature HTL, flows in a closed loop within the compressor and thermally exchanges heat with the high-temperature HTL reservoir in charge mode. In other words, the compressor has its own compressor HTL that flows in a closed loop. The HTL heats up during the compression cycle and, as part of the closed-loop flow path, exchanges heat with the high-temperature HTL reservoir and flows to heat the high-temperature HTL reservoir, which contains the high-temperature HTL used by the turbine.

[0084] In some embodiments of the system, the compressor HTL is the same as the high-temperature HTL, and in a charging mode, the high-temperature HTL reservoir is fluidly connectable to at least one two-phase compressor to supply the high-temperature HTL to the at least one compressor, i.e., the high-temperature HTL reservoir is fluidly connected to the compressor in a charging mode, and the high-temperature HTL flows between the compressor and the high-temperature HTL reservoir.

[0085] In some embodiments, the system further comprises at least one pressurizing arrangement configured to pressurize or propel the WF after it has been condensed in the at least one condenser.

[0086] In some embodiments of the system, the pressurizing arrangement comprises a pump.

[0087] In some embodiments of the system, the pressurizing arrangement is provided within a turbine.

[0088] In some embodiments of the system, the pressurizing arrangement is constituted by a turbine, i.e., the rotation of the turbine and its centrifugal force forces the WF into the turbine at the high operating pressure therein prior to quasi-isothermal expansion.

[0089] Below is a description of some exemplary embodiments of a compressor or compressor / condenser of the system of the present disclosure. It should be noted that any of the following definitions, in any combination, may be applied to and used in the system of the present disclosure.

[0090] Compressor elements are described with reference to the compressed fluid flow in a downstream flow direction. The terms "proximal" and "distal" are used to indicate a relative location upstream or downstream, respectively, with respect to a reference location. In other words, a proximal location is a location where the fluid flows before reaching a distal location.

[0091] The compressor may include a compressor pump configured to pump the HTL in a closed circle filled with the HTL, one or more WF introduction orifices, and a fluid manipulation zone disposed between a proximal suction inlet and a distal outlet. The fluid manipulation section includes four sections, including a first fluid manipulation zone having a tapered or converging wall configuration between a wider proximal end and a narrower distal end. This has the purpose of accelerating the flow of the HTL and reducing the static pressure so that it has a lower pressure upon entering the second section. This second section is a fluid mixing section, having a converging configuration between a narrower proximal end (which is also the distal end of the first section) and a wider distal end.

[0092] The WF introduction orifice may be one or more dedicated nozzles configured to introduce the WF into the second section, or an orifice defined in the wall of this section configured to introduce the WF into this zone, where it mixes with the HTL to form a HTL / WF mixture, at which stage the speed of sound decreases and the mixture velocity becomes supersonic.

[0093] The third section of the fluid manipulation zone has a tapered configuration between its proximal and distal ends configured to decelerate the supersonic HTL / WF mixture flow to sonic or subsonic velocities and increase the pressure of the two-phase mixture flowing along the third fluid manipulation section. The fourth fluid manipulation section has an expanding configuration between its proximal and distal ends and is configured to decelerate the subsonic HTL / WF mixture flow received from the third fluid manipulation section and increase its static pressure to a pressure exiting the manipulation zone outlet.

[0094] In some embodiments, the WF is a vapor that is condensed following quasi-isothermal compression, and the fluid mixture discharged from the outlet is a liquid mixture with the compressed or condensed WF in the HTL / WF mixture. That is, the WF may be drawn into the operating zone in a vapor phase, and while flowing through the various sections, the WF changes phase to a liquid and is discharged at the proximal outlet end.

[0095] In some embodiments of the operating zone, the HTL has a pressure at the distal outlet from the fourth section that is up to 2 bar, up to 1 bar, up to 0.5 bar, up to 0.3 bar, or up to 0.1 bar lower than the initial pressure value of the HTL flowing into the proximal inlet of the first section.

[0096] In some embodiments, the initial pressure value is up to 30% higher than the outlet pressure.

[0097] In some embodiments of the manipulation zone, the suction fluid flowing into the first fluid manipulation section has a velocity that is subsonic.

[0098] In some embodiments of the operation zone, the operation zone inlet is configured to be in fluid communication with an HTL source to receive HTL at a pressure greater than ambient pressure.

[0099] In some embodiments of the compressor, a separation zone is provided that is configured to receive the fluid mixture discharged from the operating zone outlet and separate the HTL and the compressed WF, and the separated compressed WF is directed to and discharged through the fluid outlet.

[0100] In some compressor embodiments, the pressurized HTL / WF mixture exits the proximal fluid outlet at the same flow rate as the HTL introduced into the proximal inlet.

[0101] In some embodiments of the compressor, the compressor pump unit is configured to receive fluid from the separation zone.

[0102] In some embodiments of the compressor, the compressor pump is a centrifugal pump, for example a vertical fluid pump.

[0103] In some embodiments of the compressor, the centrifugal pump has a fluid inlet configured to allow liquid to pass therethrough, e.g., a bottom inlet in the case of a vertical centrifugal pump, and the liquid inlet is in fluid communication with a liquid drain of a separation zone that stores the separated liquid.

[0104] In some embodiments of the compressor, the centrifugal pump has at least one arm fluidly coupled to at least one nozzle supporting fluid flow along the arm.

[0105] In some embodiments of the compressor, the vertical centrifugal pump is rotatable about a vertical axis, thereby allowing for the drawing of the HTL through the lower fluid inlet.

[0106] In some embodiments of the compressor, the HTL flows through a fluid flow path within the system, the fluid flow path including at least one closed loop flow path, i.e., the liquid separated in the separation zone is pumped back to the operation zone, and the pump unit is configured to receive and pressurize fluid from the separation zone to obtain pressurized HTL and flow it through the operation zone.

[0107] In some embodiments of the compressor, the HTL is separated by gravity from the two-phase mixture in a separation zone.

[0108] In some embodiments of the compressor, the separation zone includes a curved or circular frame through which the two-phase mixture is discharged from a nozzle, the mixture engaging the curved or circular frame causing a film flow on the surface of the curved or circular frame to separate the gas from the liquid.

[0109] 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) there is a positive pressure differential between the compressed fluid and a fluid tank fluidly coupled to the fluid outlet, or (ii) a pressure threshold of the compressed fluid is exceeded.

[0110] The present disclosure also provides a system for converting electrical energy to heat and recovering stored heat to electrical energy, the system comprising: (i) a system according to the first, second, or third system aspect; (ii) at least one generator rotatably coupled to the at least one turbine for generating electrical power in a discharge mode of operation; and (iii) at least one electric motor rotatably coupled to the at least one compressor for actuating the compressor to thermally charge at least one high temperature reservoir. Embodiment

[0111] The following numbered paragraphs (written in claim format for convenience) define several optional embodiments, including multiple independent embodiments and multiple dependent embodiments (i.e., an embodiment that references another embodiment, e.g., "the system of any one of embodiments 1-33") according to aspects of the present disclosure. These embodiments may be applied singly or in any appropriate combination. These embodiments are intended to supplement the general description set forth above, but are not intended to limit it in any way. When a particular dependent embodiment is dependent on another embodiment (referred to in this paragraph as the "reference embodiment") and includes a particular element referred to by the "the" modifier (e.g., "the second flow path"), for such dependent embodiment (and only such dependent embodiment), the modified element is deemed to be present in the reference embodiment(s) even if such element is not defined in the reference embodiment, and such element in the reference embodiment is, optionally, one of such elements described in another embodiment or in the description above.

[0112] 1. A system for storing and recovering energy in respective charge and discharge modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable or thermally coupled to at least one two-phase compressor in a charge mode of operation, for (1) supplying high-temperature HTL to the respective turbine in a discharge mode, or (2) for exchanging heat between the compressor HTL and the high-temperature HTL if the compressor HTL and the high-temperature HTL are different, or for supplying high-temperature HTL to at least one compressor if the compressor HTL and the high-temperature HTL are the same (note that the high-temperature HTL and the compressor HTL may be different, i.e., not mixed with each other, but may be the same material); at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine.

[0113] 2. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable to at least one two-phase compressor in a charge mode of operation, to supply high-temperature HTL to the respective turbine in a discharge mode, or (2) to supply high-temperature HTL to the compressor in a charge mode; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine.

[0114] 3. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high temperature HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge mode of operation, or (ii) thermally connectable to the at least one two-phase compressor in a charge mode of operation, for supplying the high temperature HTL to the respective turbine in a discharge mode, or (2) for heat exchange between the compressor HTL and the high temperature reservoir HTL in a charge mode; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine.

[0115] 4. The system of any one of embodiments 1 to 3, comprising at least one first countercurrent heat exchanger disposed in the first flow path between the at least one turbine and the at least one condenser and configured for heat exchange between the WF exiting the at least one turbine and the WF exiting the at least one condenser.

[0116] 5. The system of embodiment 4, wherein the heat exchanger is configured to reduce the temperature of the WF flowing from the turbine to the condenser.

[0117] 6. The system of any one of embodiments 1 to 5, comprising at least one pressurizing arrangement configured to pressurize or propel the WF after condensation in the at least one condenser.

[0118] 7. The system of embodiment 6, wherein the configuration comprises a pump.

[0119] 8. The system of any one of embodiments 1-7, comprising at least one first separation zone disposed in at least one turbine for separating the WF and the HTL.

[0120] 9. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable or thermally coupled to at least one two-phase compressor in a charge mode of operation, for (1) supplying high-temperature HTL to the respective turbine in a discharge mode, or (2) for exchanging heat between the compressor HTL and the high-temperature HTL if the compressor HTL and the high-temperature HTL are different, or for supplying high-temperature HTL to at least one compressor if the compressor HTL and the high-temperature HTL are the same (note that the high-temperature HTL and the compressor HTL may be different, i.e., not mixed with each other, but may be the same material); at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a charging mode, the WF flows through the second flow path, and the at least one compressor is configured to heat the compressor HTL by forming a compressor HTL / WF mixture and quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL heats the high-temperature HTL reservoir by exchanging heat with the high-temperature HTL reservoir, and is circulated to the same or a different reservoir as the high-temperature HTL reservoir or is circulated within the at least one compressor, the compressed WF is discharged from the at least one compressor and flows to and received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0121] 10. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high temperature HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge mode of operation, or (ii) thermally connectable to the at least one two-phase compressor in a charge mode of operation, for supplying the high temperature HTL to the respective turbine in a discharge mode, or (2) for heat exchange between the compressor HTL and the high temperature reservoir HTL in a charge mode; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a charging mode, the WF flows through the second flow path, and at least one compressor is configured to form a compressor HTL / WF mixture and heat the compressor HTL by quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL heats the high-temperature HTL reservoir by exchanging heat with the high-temperature HTL reservoir, and is circulated to the same or a different reservoir as the high-temperature HTL reservoir or circulated within the compressor, the compressed WF is discharged from the at least one compressor and flows to and received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0122] 11. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable to at least one two-phase compressor in a charge mode of operation, to supply high-temperature HTL to the respective turbine in a discharge mode, or (2) to supply high-temperature HTL to the at least one compressor; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a charging mode, the WF flows through the second flow path, and at least one compressor is configured to receive the WF and the high-temperature HTL to obtain a HTL / WF mixture and heat the high-temperature HTL by quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL heats the high-temperature HTL reservoir by exchanging heat with the high-temperature HTL reservoir and is circulated to the high-temperature HTL reservoir or the compressor, the compressed WF is discharged from the at least one compressor and flows to and received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0123] 12. The system of any one of embodiments 9-11, comprising at least one second countercurrent heat exchanger disposed between the at least one compressor and the at least one evaporator in the second flow path and configured for heat exchange between the WF exiting the at least one compressor and the WF exiting the at least one evaporator.

[0124] 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.

[0125] 14. The system of any one of embodiments 9-13, comprising at least one second separation zone disposed in the at least one turbine for separating the HTL and the WF.

[0126] 15. The system of any one of embodiments 9-14, comprising at least one pressure reducing nozzle disposed in the second flow path between the at least one second heat exchanger and the at least one evaporator to reduce the pressure and temperature of the WF flowing from the at least one second heat exchanger to the at least one evaporator.

[0127] 16. The system of any one of embodiments 1-15, wherein the WF is a liquid-vapor-phase change (LVPhC) WF selected to be (i) in the vapor phase when (1) entering the at least one compressor, (2) at temperature equilibrium after being mixed with the HTL in the at least one turbine, and (3) when exiting the at least one evaporator, and (ii) in the liquid phase when (4) exiting the at least one condenser, and (5) when exiting the at least one compressor.

[0128] 17. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable or thermally coupled to at least one two-phase compressor in a charge mode of operation, for (1) supplying high-temperature HTL to the respective turbine in a discharge mode, or (2) for exchanging heat between the compressor HTL and the high-temperature HTL if the compressor HTL and the high-temperature HTL are different, or for supplying high-temperature HTL to at least one compressor if the compressor HTL and the high-temperature HTL are the same (note that the high-temperature HTL and the compressor HTL may be different, i.e., not mixed with each other, but may be the same material); at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one first condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and the HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine. In a charging mode, the WF flows through the second flow path, and the at least one compressor is configured to heat the compressor HTL by forming a compressor HTL / WF mixture and quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL is circulated to a reservoir the same as or different from the high-temperature HTL reservoir or to the at least one compressor, the compressed WF is discharged from the at least one compressor and flows to and received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0129] 18. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor configured to compress the same or different compressor HTL as the high-temperature HTL of the high-temperature reservoir; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to the at least one two-phase turbine in a discharge mode of operation, or (ii) thermally connectable to the at least one two-phase compressor in a charge mode of operation, for supplying the high-temperature HTL to the respective turbine in a discharge mode, or (2) for heat exchange between the compressor HTL and the high-temperature HTL in a charge mode; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one first condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and the HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine. In a charging mode, the WF flows through the second flow path, and the at least one compressor is configured to heat the compressor HTL by forming a compressor HTL / WF mixture and quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL is circulated to a reservoir or the at least one compressor, the compressed WF is discharged from the at least one compressor and flows to and received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0130] 19. A system for storing and recovering energy in respective charging and discharging modes of operation, comprising: at least one high temperature heat transfer liquid (HTL) reservoir containing a high temperature HTL; at least one two-phase turbine and at least one two-phase compressor; Equipped with wherein the at least one high-temperature HTL reservoir is selectively (i) fluidly connectable to at least one two-phase turbine in a discharge mode of operation, or (ii) fluidly connectable to at least one two-phase compressor in a charge mode of operation, to supply high-temperature HTL to the respective turbine in a discharge mode, or (2) to supply high-temperature HTL to the at least one compressor; at least one condenser in fluid communication with the turbine for receiving and condensing an incoming working fluid (WF) from the turbine; at least one evaporator, which may be the same or different element as the at least one condenser, in fluid communication with the at least one compressor for receiving and evaporating the WF entering from the at least one compressor; Furthermore, The discharge mode defines a first flow path for the WF, and the charge mode defines a second flow path for the WF; In a discharge mode, the WF flows in a first flow path from at least one first condenser to one or more nozzles in at least one turbine, the nozzles configured to induce rotation of the turbine when discharging the fluid, thereby mixing the WF and the HTL in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, resulting in acceleration of the HTL / WF mixture and discharge of the mixture through the one or more nozzles while decreasing the temperature of the HTL. The HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL. The HTL is recycled to the at least one high-temperature reservoir or the one or more nozzles. The separated WF flows into and is received by a condenser to undergo condensation. The condensed WF is discharged from the at least one condenser and returned to the turbine. In a charging mode, the WF flows through the second flow path, and the at least one compressor is configured to receive the high-temperature HTL and WF to form a HTL / WF mixture and heat the compressor HTL by quasi-isothermally compressing the WF in the mixture along the compressor flow path, the HTL is circulated to the high-temperature HTL reservoir or the at least one compressor, the compressed WF is discharged from the at least one compressor and flows to and is received by an evaporator to undergo evaporation, and the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor, the system.

[0131] 20. A system for storing and recovering energy in respective charging and discharging modes, comprising: at least one two-phase turbine and at least one two-phase compressor; at least one high-temperature HTL reservoir containing a high-temperature HTL and at least one low-temperature HTL reservoir containing a low-temperature HTL, each selectively fluidly connectable to at least one compressor or 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; Equipped with In a charging mode, the at least one compressor is fluidly connected to and receives high-temperature HTL from the at least one high-temperature HTL reservoir and quasi-isothermally compresses a working fluid (WF) mixed with the high-temperature HTL; the compressed working fluid flows through at least one first heat exchanger to reduce its temperature and then mixes with the low-temperature HTL in one or more nozzles of the turbine and undergoes isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and working fluid and generate kinetic energy convertible to electrical energy; the working fluid discharged from the turbine is directed to the at least one first heat exchanger and heated for another cycle; In a discharge mode, the at least one compressor is configured to receive low-temperature HTL from the low-temperature HTL reservoir and quasi-isothermally compress the working fluid mixed with the low-temperature HTL, the compressed working fluid flows through at least one first heat exchanger to increase its temperature and then mixes with the high-temperature HTL in one or more nozzles of the turbine and undergoes isothermal or quasi-isothermal expansion to accelerate the HTL / WF mixture and generate kinetic energy that can be converted into electrical energy, and the working fluid discharged from the at least one turbine is directed to the at least one first heat exchanger to be cooled for another cycle.

[0132] 21. A system for storing and recovering energy in respective charging and discharging modes, comprising: at least one two-phase turbine and at least one two-phase compressor configured to compress the compressor HTL; at least one high-temperature HTL reservoir including a high-temperature HTL and at least one low-temperature HTL reservoir including a low-temperature HTL, each selectively connectable to and thermally coupled to at least one compressor or 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; Equipped with 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 heat the compressor HTL by quasi-isothermally compressing the compressor HTL / WF mixture; the compressor is thermally coupled to at least one high-temperature HTL reservoir and exchanges heat between the compressor HTL and the high-temperature HTL reservoir; the compressed WF flows through at least one first heat exchanger to reduce its temperature and is then mixed with the low-temperature HTL in one or more nozzles of the turbine and undergoes isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and working fluid and generate kinetic energy convertible to electrical energy; and the working fluid discharged from the turbine is directed to the at least one first heat exchanger and heated for another cycle; In a discharge mode, the at least one compressor is configured to mix the WF with the compressor HTL to form a compressor HTL / WF mixture and heat the compressor HTL by quasi-isothermally compressing the compressor HTL / WF mixture; the compressor is thermally coupled to at least one low-temperature HTL reservoir and exchanges heat between the compressor HTL and the low-temperature HTL reservoir; the compressed working fluid flows through at least one first heat exchanger to increase its temperature and is then mixed with the high-temperature HTL in one or more nozzles of the turbine and undergoes isothermal or quasi-isothermal expansion to accelerate the HTL / WF mixture and generate kinetic energy that can be converted into electrical energy; and the working fluid discharged from the at least one turbine is directed to the at least one first heat exchanger to be cooled for another cycle.

[0133] 22. A system for storing and recovering energy in respective charging and discharging modes, comprising: at least one two-phase turbine and at least one two-phase compressor; at least one high-temperature HTL reservoir containing a high-temperature HTL and at least one low-temperature HTL reservoir containing a low-temperature HTL, each selectively connectable to at least one compressor / condenser or at least one turbine; at least one intermediate exchanger disposed in a flow path between the at least one compressor and the at least one turbine; Equipped with In a charging mode, the at least one compressor / condenser is fluidly connected to the at least one high-temperature HTL reservoir to receive the high-temperature HTL therefrom, and quasi-isothermally compresses and condenses the working fluid in a liquid-to-vapor phase change working fluid (LVPhC) mixed with the high-temperature HTL; the condensed LVPhC flows through the at least one first heat exchanger to reduce its temperature, and then mixes with the low-temperature HTL in one or more nozzles of the turbine to evaporate it and undergoes isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and evaporated LVPhC and generate kinetic energy convertible to electrical energy; and the evaporated LVPhC discharged from the turbine is directed to the at least one first heat exchanger to be heated for another cycle; In a discharge mode, the at least one compressor is configured to receive low-temperature HTL from the low-temperature HTL reservoir and quasi-isothermally condense and compress LVPhC mixed with the low-temperature HTL, the condensed LVPhC flows through at least one first heat exchanger to increase its temperature, and then mixes with the high-temperature HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and LVPhC to generate kinetic energy convertible to electrical energy, and the LVPhC discharged from the at least one turbine is directed to the at least one first heat exchanger to be cooled for another cycle, the system.

[0134] 23. A system for storing and recovering energy in respective charging and discharging modes, comprising: at least one two-phase turbine and at least one two-phase compressor configured to compress the compressor HTL; at least one high-temperature HTL reservoir including a high-temperature HTL and at least one low-temperature HTL reservoir including a low-temperature HTL, each selectively connectable to and thermally coupled to at least one compressor or at least one turbine; at least one intermediate exchanger disposed in a flow path between the at least one compressor and the at least one turbine; Equipped with In a charging mode, the at least one compressor / condenser is thermally coupled to the at least one high-temperature HTL reservoir to exchange heat with the high-temperature HTL reservoir, the at least one compressor / condenser is configured to mix a liquid-to-vapor phase change (LVPhC) working fluid (WF) with the compressor HTL to form a compressor HTL / WF mixture, and heat the compressor HTL by quasi-isothermally compressing and condensing the compressor HTL / WF mixture, the condensed LVPhC flows through at least one first heat exchanger to reduce its temperature, and then mixes with the low-temperature HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion to accelerate the mixture of HTL and evaporated LVPhC to generate kinetic energy convertible to electrical energy, and the evaporated LVPhC discharged from the turbine is directed to the at least one first heat exchanger to be heated for another cycle. In a discharge mode, the at least one compressor / condenser is thermally coupled to the at least one low-temperature HTL reservoir to exchange heat with the low-temperature HTL reservoir, the at least one compressor / condenser is configured to mix the WF with the compressor HTL to form a compressor HTL / WF mixture, and quasi-isothermally compress 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 high-temperature HTL in one or more nozzles of the turbine to evaporate and undergo isothermal or quasi-isothermal expansion to accelerate the HTL and LVPhC mixture and generate kinetic energy convertible to electrical energy, and the LVPhC discharged from the at least one turbine is directed to the at least one first heat exchanger to be cooled for another cycle.

[0135] 24. The system of any one of embodiments 1-23, wherein at least one evaporator and at least one condenser are the same element.

[0136] 25. The system of any one of embodiments 1 to 24, comprising at least one first countercurrent heat exchanger disposed in the first flow path between the at least one turbine and the at least one condenser and configured to exchange heat between the WF exiting the at least one turbine and the WF exiting the at least one condenser.

[0137] 26. The system of embodiment 25, wherein the heat exchanger is configured to reduce the temperature of the WF flowing from the turbine to the condenser.

[0138] 27. The system of any one of embodiments 1 to 26, comprising at least one second countercurrent heat exchanger disposed between the at least one compressor and the at least one evaporator in the second flow path and configured to exchange heat between the WF exiting the at least one compressor and the WF exiting the at least one evaporator.

[0139] 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.

[0140] 29. The system of embodiment 27 or 28, comprising both the at least one first heat exchanger and the at least one second heat exchanger, wherein the at least one first countercurrent heat exchanger and the at least one second countercurrent heat exchanger are the same element or elements selectively connectable to the at least one turbine or the at least one compressor in a respective discharge mode or charge mode.

[0141] 30. The system of any one of embodiments 1-29, comprising at least one pressurizing arrangement configured to pressurize or propel the WF after condensation in the at least one condenser.

[0142] 31. The system of embodiment 30, wherein the configuration includes a pump.

[0143] 32. The system of any one of embodiments 1-31, comprising at least one first separation zone disposed in at least one turbine for separating the WF and the HTL.

[0144] 33. A system according to any one of embodiments 1 to 32, comprising at least one second separation zone disposed within the at least one compressor for separating WF and HTL.

[0145] 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 the at least one second heat exchanger and the at least one evaporator to reduce the pressure and temperature of the WF flowing from the at least one second heat exchanger to the at least one evaporator.

[0146] 35. The system of any one of embodiments 1-34, wherein the WF is a liquid-vapor-phase change (LVPhC) WF selected to be (i) in the vapor phase when (1) entering the at least one compressor, (2) at temperature equilibrium after being mixed with the HTL in the at least one turbine, and (3) when exiting the at least one evaporator, and (ii) in the liquid phase when (4) exiting the at least one condenser, and (5) when exiting the at least one compressor.

[0147] 36. The system of any one of embodiments 1-35, wherein either or both of the at least one compressor and the at least one turbine are thermally insulated.

[0148] 37. The system of any one of embodiments 1-36, comprising one or more selection valves for enabling selective connection of at least one high-temperature HTL reservoir to at least one compressor and at least one turbine.

[0149] 38. The system of any one of embodiments 1 to 37, wherein the HTL is selected from the list consisting of antifreeze liquid, water, brine, heat transfer oil, molten salt, ethylene glycol, and WF in liquid phase.

[0150] 39. The system of any one of embodiments 1 to 38, wherein the WF is selected from the list consisting of air, nitrogen, CO2, ammonia, propane, ORC phase change material, pentane, and refrigerated phase change material.

[0151] 40. A system according to any one of embodiments 1 to 39, comprising at least one external heat source for enabling controllable heating of the high-temperature HTL.

[0152] 41. A system according to any one of embodiments 1 to 40, wherein at least one condenser and at least one evaporator are configured to exchange heat with the surroundings for condensation and evaporation, respectively.

[0153] 42. The system of any one of embodiments 1-41, wherein at least one evaporator is configured for heating by at least one external heat source in a charging mode of operation.

[0154] 43. The system of embodiment 42, comprising at least one condenser or at least one evaporator, and a thermally insulated enclosure configured for heat input from an external heat source and controlled exhaust of excess heat.

[0155] 44. The system of any one of embodiments 1-43, wherein the at least one first countercurrent heat exchanger and the at least one second countercurrent heat exchanger are recuperators.

[0156] 45. The system of any one of embodiments 1-44, wherein at least one intermediate heat exchanger is a recuperator.

[0157] 46. ​​The system of any one of embodiments 1-45, wherein the inlet compressor pressure of the WF and the pressure of the WF in the evaporator are below the critical pressure at temperatures below ambient temperature, thereby allowing evaporation of the WF and heat flow from the ambient to the WF vapor.

[0158] 47. A system according to any one of embodiments 1 to 46, wherein the at least one first heat exchanger comprises at least one first heat pendulum.

[0159] 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 heat pendulum section, and the flow path of the WF between the first and second heat exchanger sections is through the heat pendulum.

[0160] 49. The system of any one of embodiments 1-48, wherein the second heat exchanger comprises a second heat pendulum.

[0161] 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 heat pendulum section, and the flow path of the WF between the first and second heat exchanger sections is through the second heat pendulum.

[0162] 51. A system described in any one of embodiments 49 and 50, wherein the second thermal pendulum is the same as the first thermal pendulum.

[0163] 52. The system of any one of embodiments 1-51, wherein at least one intermediate heat exchanger comprises at least one intermediate heat pendulum.

[0164] 53. The system of embodiment 52, wherein each of the at least one intermediate heat exchanger comprises a first heat exchanger section, a second heat exchanger section, and an intermediate heat pendulum section, and the flow path of the WF between the first and second heat exchanger sections is through the heat pendulum.

[0165] 54. The system of any one of embodiments 47-53, wherein the thermal pendulum has a heat capacity value greater than the heat capacity of the WF in the liquid phase and is configured to exchange heat with the passing WF so that (1) in a charging operation mode, the thermal pendulum heats up while cooling the liquid before it enters the turbine, and (2) in a discharging operation mode, the thermal pendulum cools down while heating the liquid before it enters the turbine, thereby compensating for inefficiencies in heat exchange between the liquid phase of the WF and the gas phase of the WF.

[0166] 55. The system of any one of embodiments 1-54, wherein the first flow path and the second flow path are closed-loop flow paths.

[0167] 56. The system of any one of embodiments 1-55, 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 said one or more nozzles to mix with WF at approximately the same pressure to form an HTL / WF mixture, and then quasi-isothermal expansion of the WF in the one or more nozzles accelerates the HTL / WF mixture towards the outlet of the one or more nozzles.

[0168] 57. The system of any one of embodiments 1-56, wherein at least one compressor comprises an HTL pump for increasing the HTL pressure, the HTL pump is fluidly coupled to a compressor nozzle configured to receive pressurized HTL from the HTL pump and mix with the WF in the nozzle to obtain an HTL / WF mixture, and the HTL / WF mixture is discharged from the nozzle at a pressure higher than the pressure of the WF introduced into the compressor.

[0169] 58. A system according to any one of embodiments 1 to 57, wherein at least one WF pump is provided within at least one condenser.

[0170] 59. The system of any one of embodiments 1-58, wherein the evaporator is maintained at a temperature higher than ambient temperature.

[0171] 60. A system according to any one of embodiments 1 to 59, wherein the compressor HTL is distinct from the high-temperature HTL and flows in a closed loop within the compressor, thermally exchanging heat with the high-temperature HTL reservoir in charging mode.

[0172] 61. The system of any one of embodiments 1 to 60, wherein the compressor HTL is the same as the high-temperature HTL, the compressor HTL reservoir is the same as the high-temperature HTL reservoir, and in a charging mode, the high-temperature HTL reservoir is fluidly connected to at least one two-phase compressor to supply high-temperature HTL to the at least one compressor.

[0173] 62. A system for converting electrical energy into heat and recovering stored heat into electrical energy, comprising: A system according to any one of embodiments 1 to 61; at least one generator rotatably coupled to the at least one turbine for generating electricity in a discharge mode of operation; at least one electric motor rotatably coupled to the at least one compressor for actuating the compressor to hot charge the at least one hot reservoir; A system comprising:

[0174] For a better understanding of the subject matter disclosed herein and to illustrate how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0175] [Figure 1] 1 is a schematic diagram of a prior art configuration of a thermal energy storage system; [Figure 2]Schematic diagram showing a two-phase nozzle for both reaction and impulse turbine configurations, mixing compressed gas or steam with an HTL, supporting quasi-isothermal expansion, accelerating the HTL, and generating thrust in the turbine that is converted to electrical power or mechanical work. [Figure 3] FIG. 1 is a schematic diagram of a compressor / condenser using an HTL in a closed loop to compress and optionally condense a working fluid. [Figure 4] FIG. 1 is a schematic diagram of a nozzle used in an HTL-based compressor / condenser. [Figure 5A-5B] 5A and 5B are schematic diagrams of system configurations of non-limiting embodiments of a system comprising a high-temperature HTL reservoir and a low-temperature HTL reservoir, with Figure 5A showing the charge mode and Figure 5B showing the discharge mode. [Figure 6] FIG. 1 is a schematic diagram of a rotary slice type ball valve to allow the exchange of liquid between the hot and cold sections without consuming work that can be used in the system. [Figures 7A-7B] 7A and 7B show the PV and TS diagrams of the system for each mode, with FIG. 7A showing the diagram for the charge mode and FIG. 7B showing the diagram for the discharge mode in an embodiment where the WF is a gas. [Figure 8] FIG. 1 is a PV diagram of an isothermal organic cycle for a system using a liquid / vapor phase change working fluid. [Figure 9] The TS diagram for the thermodynamic cycle using two-phase pentane as the working fluid and ethylene glycol as the HTL is shown. [Figure 10A-1B] 10A and 10B are schematic diagrams of system modes of a non-limiting embodiment of a system with a high temperature HTL reservoir and a low temperature HTL reservoir using a liquid / vapor phase change working fluid, where FIG. 10A shows the charge mode and FIG. 10B shows the discharge mode. [Figure 11] 1 shows charge and discharge TS diagrams for an isothermal phase change thermodynamic cycle at a fixed pressure level. [Figure 12] 1 shows charge and discharge TS diagrams for an isothermal phase change thermodynamic cycle at varying pressure levels. [Figures 13A-13B]13A and 13B are schematic diagrams of non-limiting embodiments of a system comprising low-temperature and high-temperature HTL reservoirs, two recuperators, and a thermal pendulum, with Fig. 13A showing the charging mode and Fig. 13B showing the discharging mode. [Figures 14A-14B] 14A and 14B are schematic diagrams of non-limiting embodiments of a system with only a high temperature HTL reservoir, a single recuperator, and a compressor and evaporator, which may be the same element: Figure 14A shows the discharge mode with the condenser, and Figure 14B shows the charge mode with the evaporator. [Figures 15A-15B] Efficiency heat and mass balance calculations are shown for the case of a temperature of 140° C. FIG. 15A shows the discharge mode and FIG. 15B shows the charge mode. [Figure 16] 15A-15B show pentane TS diagrams illustrating the enthalpy and entropy associated calculations, including the 140° C. case illustrated in FIGS. 15A-15B. [Figures 17A-17B] FIG. 1 is a block diagram illustrating a non-limiting embodiment of the system of the present disclosure in which the WF exchanges heat with the ambient in a condenser / evaporator. DETAILED DESCRIPTION OF THE INVENTION

[0176] The following drawings are provided to illustrate embodiments and implementations of the invention of the present disclosure.

[0177] In this disclosure, the solution utilizes the Carnot cell concept of isothermal expansion and compression in a cellular medium. The liquid in the cellular medium reduces system size and cost by increasing the thermal power density per volume by a factor of 1000, and the bubbles exhibit isothermal expansion and compression, boosting efficiency compared to adiabatic processes.

[0178] The core component of this method and system is a nozzle that mixes compressed gas or vapor with a heat transfer liquid (HTL). The HTL is maintained in a liquid state within the nozzle. Optionally, vapor is produced as a result of evaporation of a phase change material, achieved by mixing the HTL with a phase change material within the nozzle. Optionally, evaporation occurs before reaching the nozzle. The vapor or gas mixed with the HTL forms bubbles that expand within the nozzle, maintaining approximately the same temperature as the HTL, due to the large heat capacity of the HTL and excellent heat transfer between the vapor bubbles and the HTL. The thermal energy density is determined by the HTL and far exceeds the heat capacity of the vapor per volume. This allows for thin pipes and compact systems to have high power output. The expansion accelerates the mixing within the nozzle. Both the HTL and the vapor cool as they expand. This temperature drop is less than a few degrees, supporting quasi-isothermal expansion of the gas or vapor. Optionally, the velocity of the mixture becomes supersonic. Within the nozzle, a portion of the initial pressure and thermal energy of the HTL is converted into kinetic energy under quasi-isothermal conditions. The kinetic energy is used to rotate a turbine and generate electrical power, mechanical work, or another form of work. Examples of such nozzles are described in WO 2022 / 049573, the entire contents of which are incorporated herein by reference. For example, the HTL flowing through the nozzle is molten salt or thermal oil. Compressed air, nitrogen, ammonia, or other gas is injected into the nozzle, mixed with the HTL, and quasi-isothermally expands, accelerating the HTL and generating thrust that is converted into electrical power by the turbine. The power generated by the turbine can be used in part to drive (via a mechanical shaft or electrical connection) a compressor that isothermally compresses the gas at a low temperature. The HTL in the turbine cools after several cycles and must be replaced with high-temperature HTL for continuous heat exchange for operation. Figure 2 shows a two-phase nozzle for both reaction and impulse configurations, mixing compressed gas or steam with the HTL, supporting quasi-isothermal expansion, accelerating the HTL, and generating thrust that is converted into electrical power or mechanical work in the turbine.

[0179] For two-phase flow, reaction turbines have advantages over impulse turbines due to the elimination of cavitation, which can damage impulse turbines. Also, the maximum static pressure at the reaction turbine's edge is ideal for injecting the gas phase with minimal head loss. Finally, the non-zero velocity exit jet in a reaction turbine is used to separate gas / liquid mixtures by directing the jet at a circular frame, inducing film flow on the frame wall that disrupts the gas bubbles and defines a separation zone.

[0180] Another core component is the continuous isothermal compressor and condenser. The term compressor is used to compress a gas or vapor that is maintained as a compressed gas or vapor. The term condenser refers to the same device, but the compressed vapor is liquefied.

[0181] Optionally, the HTL in the compressor / condenser is water, an organic liquid such as ethylene glycol, the same organic material as an organic vapor in the liquid phase, or any other liquid that has a liquid phase at the operating temperature. The HTL inlet temperature is between -200°C and 1000°C or higher. Optionally, the low-temperature HTL is used to compress or liquefy air, nitrogen, hydrogen, CO2, or any other gas for charging the low-temperature reservoir. Optionally, the high-temperature HTL is used to charge the high-temperature reservoir. This is achieved by thermally insulating the compressor so that all input work is converted to conserved pressure and temperature. In such an adiabatic system, compression is quasi-isothermal due to the large heat capacity of the liquid, maintaining a lower temperature for the compressed gas compared to conventional adiabatic expansion without mixing the gas with the HTL. Also, optionally, a modest temperature difference of 50°C, 100°C, or 200°C is used between the high-temperature and low-temperature thermal reservoirs.

[0182] An optional method and system for condensing and compressing a gas or vapor is illustrated in FIG. 3 . The system is designed to reduce compressor size and cost by increasing the surface area between the compressed liquid and the compressed gas or vapor. A closed-loop flow of HTL is driven by a pump at a pressure above that of the incoming gas or vapor. A nozzle is designed to reduce the pressure below that of the incoming gas or vapor. This draws the gas or vapor into the HTL flow. The gas or vapor enters from a surrounding envelope or through a designated pipe. The gas or vapor and HTL mix within the nozzle. In the case of a vapor, the vapor optionally liquefies due to the temperature of the HTL and its higher heat capacity per volume compared to the vapor. The nozzle geometry is designed to increase the pressure at the nozzle outlet above the inlet pressure after mixing. Optionally, in the case of a vapor, some of the phase change material remains in the vapor phase and is compressed as a gas. Optionally, after the pressure is increased above the critical pressure, most of the vapor is liquefied. Optionally, mixing of the gas / HTL or vapor / HTL results in a sonic velocity lower than the flow velocity of the mixture, resulting in supersonic flow within the nozzle. In this case, a reverse Laval nozzle is designed as described below. Optionally, compression is isothermal or quasi-isothermal, meaning that the HTL and gas or vapor maintain similar temperatures, less than 10% or 20% Kelvin difference, as they compress. Optionally, after the nozzle, the pressure increases, the flow slows, and the mixture is separated by gravity, centrifugal action, or any other separation method. The gas, vapor, or liquid phase of the phase change material collects (at the top, if it has a lower density than the HTL) while the HTL reaches the pump and continues to circulate. The HTL heats up as it compresses. Optionally, for continuous operation of the compressor, the hot HTL is replaced with cooled HTL (not shown). Optionally, cooling of the HTL without replacement is achieved by heat transfer to the surroundings via the flow surface. Optionally, the HTL is heated for storage of thermal energy. Optionally, the compressor pressure at suction is below ambient pressure, for example 0.7 bar.This allows the compressor to operate between the maximum compression pressure and the minimum inlet pressure, in this example, 0.7 bar. At steady state, the HTL temperature can be high enough for the HTL to evaporate under the low pressure in the low-pressure region. In this case, the flow duration in the low-pressure region is significantly shorter than the heat exchange rate. That is, the HTL does not have enough time to absorb heat of evaporation from the environment and remains liquid; the HTL and vapor can be the same material. For example, pentene vapor is compressed with liquid pentene as the HTL flows through the compressor. This condition supports a vapor phase in the low-pressure region, but as long as the flow in the low-pressure region is faster than the heat transfer rate, no phase change occurs. Instead, the liquid attracts the pentene vapor entering from the turbine, condensing and compressing the pentene. The advantage is that phase separation (bubbles) during the compression stage is eliminated, accelerating the condensation process.

[0183] The compressor nozzle illustrated in FIG. 4 may include the following sections, in order: 1. A converging inlet section consisting of only HTL (water as a non-limiting example) to reduce pressure above ambient pressure. 2. A branching two-phase flow section where pressure is maintained constant while gas or vapor (air as a non-limiting example) is drawn into the HTL from the surroundings through holes or voids in the nozzle envelope. The section marked "-" is the beginning of the suction, and the section marked "+" is the end of the suction. The mixture reduces the sonic velocity below the mixture velocity. At the end of the "branching two-phase flow section" (marked "+"), the flow is supersonic. For more information on supersonic two-phase flow, see "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. 3. A converging two-phase section where the mixture pressure increases and the Mach number (ratio of injection speed to the speed of sound) decreases. At the end of this section, marked with an *, Mach number = 1. (For supersonic two-phase flow, see "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.) 4. The branching two-phase outlet, where the mixture pressure increases and the Mach number decreases. At the end of this section, the mixture (as a mixture, since the HTL itself has a higher pressure when injected into the nozzle) reaches its maximum pressure. (For supersonic two-phase flow, see "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.)

[0184] Returning to the system, in one configuration of the system, the storage system includes high-temperature and low-temperature HTL reservoirs, a quasi-isothermal, thermally isolated compressor, a thermally isolated turbine, a working fluid in the form of a gas, a heat exchanger for the gas, and an HTL. The gas may be nitrogen, air, CO2, or any other gas, and the HTL may be any liquid maintained as a liquid within the operating temperature range between the two HTL reservoirs. Optionally, a different HTL is used in the high-temperature reservoir than in the low-temperature reservoir. This requires a filter to isolate the two HTLs for mixing. Optionally, the same HTL is used in the two reservoirs. During the charging process, electrical or mechanical power input is used to create a temperature difference between the high-temperature T_h and low-temperature T_c HTL reservoirs. During the discharging process, the temperature difference is converted to output power.

[0185] An example of a storage system material and operating temperature is using nitrogen gas as the working fluid (WF) and ethylene glycol as the HTL, with a temperature range of -40° C. to 200° C. Optionally, ethylene glycol mixed with water is the HTL.

[0186] The charging process is shown in Figure 5A. Electric power drives a quasi-isothermal, thermally isolated compressor. Nitrogen is compressed from low pressure P_L to high pressure P_h and heated to T_h in the HTL. The temperatures of the compressed nitrogen and HTL continue to increase as the compressor operates until they reach a maximum value, T_h_max = 199 °C for ethylene glycol. As the compressor operates, the compressed nitrogen exits the compressor at any T_h between T_L and T_h_max and reaches the heat exchanger, where its temperature drops to a lower temperature T_c. The compressed, low-temperature nitrogen reaches the turbine and expands quasi-isothermally in the nozzle, accelerating and cooling the HTL, generating thrust that is converted into electrical power or mechanical work in the turbine. This electrical power or mechanical work supports the compressor operation and reduces the external power required. The HTL and gas in the turbine cool as they expand. The HTL remains in the turbine and is cooled each cycle until it reaches a minimum temperature, T_L_min. The cooled nitrogen is returned to the heat exchanger, which recovers heat and raises its temperature to T_h. This cycle continues until the gas returns to the compressor. After several cycles, the temperature difference reaches a maximum value (-40°C and 199°C for ethylene glycol). Optionally, high and low temperature HTL reservoirs are connected to the compressor and turbine for charging the reservoirs. Optionally, the turbine is connected to a circulation pump to the low temperature HTL reservoir for charging the HTL. The compressor is maintained at high pressure. Optionally, the HTL high temperature reservoir connected to the compressor is also at high pressure.

[0187] Since it is possible to feed and extract the same amount of liquid to and from the compressed tank without performing work (no change in compressed gas volume), it is possible to maintain the high temperature reservoir at low pressure while mixing the HTL in the compressor. Optionally, this is done by simultaneously inserting and extracting the same amount of liquid from the compressor. Figure 6 shows an optional mechanism for this. A set of ball valves, blocked for direct current, is placed in the wall between the high pressure side P_h and the low pressure side P_L. The HTL fills the empty space in the ball valves. Rotating the ball valves exchanges the liquid without investing significant work.

[0188] The charging process can be explained in the PV-TS diagram shown in Figure 7A. It operates as a reverse Ericsson thermal cycle. The compressor compresses at high temperature using a high-temperature reservoir. The gas is compressed quasi-isothermally by mixing with HTL. The gas is then cooled in a heat exchanger, optionally at constant pressure, and reaches a turbine connected to a low-temperature reservoir, where it expands quasi-isothermally.

[0189] For discharge, the reservoir connections are switched so that the hot reservoir exchanges the HTL with the turbine and the cold reservoir exchanges the HTL with the compressor. Discharge mode is shown in Figure 5B. For ramp-up, the compressor maintains the nitrogen in a compressed state. Optionally, a separate chamber of compressed nitrogen is used for ramp-up. When the valve in the compressor or chamber opens, the compressed nitrogen at high pressure P_h and low temperature T_c passes through the heat exchanger and reaches the turbine at high temperature T_h. It mixes with the hot HTL in the nozzle and expands quasi-isothermally, generating thrust in the turbine, which is converted to electrical power or mechanical work. A portion of the electrical power or mechanical work is transferred to the compressor. The HTL and nitrogen cool as they expand during each cycle. The nitrogen returns to the heat exchanger at the high temperature HTL temperature T_h and low pressure P_L and exits 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 the compression of the gas at a lower temperature and the expansion of the gas at a higher temperature produces work, similar to a heat engine. This cycle continues as long as the temperature difference supports positive energy production.

[0190] The discharge process can be explained in the PV-TS diagram shown in Figure 7B. It operates as an Ericsson thermal cycle. The compressor compresses the gas at low temperature using a low-temperature reservoir. The gas is compressed quasi-isothermally by mixing with HTL. The gas is then heated in a heat exchanger, optionally at constant pressure, and reaches a turbine connected to a high-temperature reservoir, where it expands quasi-isothermally.

[0191] The system is designed to store electrical energy via thermal energy and convert it back into electrical power. Optionally, if a high or low temperature heat source is available, the high or low temperature reservoir exchanges heat with the heat source to reach the desired temperature without electrical power input. In such a case, the second reservoir is at ambient temperature, and the amount of electrical power that can be extracted depends on the temperature difference between the heated (or cooled) reservoir and the ambient temperature. Optionally, electrical power is used in addition to the heat source to further increase the temperature difference between the heat sources that is converted into electrical power. Optionally, if the low temperature reservoir is at a higher temperature than ambient, air can be used to cool the low temperature reservoir, increasing the electrical power extracted.

[0192] The nitrogen example can also be replaced with an organic material, as in the Organic Rankine Cycle (ORC). In this case, power used in the compressor condenses the vapor into a liquid, similar to the ORC. The liquid evaporates in the turbine nozzle and expands quasi-isothermally in the turbine, cooling the HTL. The ORC material then reaches a heat exchanger and returns to the compressor / condenser for an additional cycle. As an example, an ORC material such as ethylene glycol as the HTL and propane as the working fluid could be used. Any other ORC material that has a liquid phase at the low HTL temperature and a gas phase at the high HTL temperature could be considered.

[0193] 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 ventilation. Optionally, ventilation or other external work investment is used to slow the cooling rate of the hot reservoir during discharge.

[0194] At low temperatures (<200°C), a typical Ericsson-based Carnot cell has a round-trip efficiency below 50% due to increased compressor work. The present invention can utilize a new thermodynamic cycle based on the isothermal bubble expansion of an organic liquid / vapor phase change (LVPhC) working fluid in a two-phase nozzle. In the case of a Carnot cell, such a new engine has a significant advantage over the Ericsson cycle operating at low temperatures because the phase change reduces the compressor load by limiting the pressure rise.

[0195] Optionally, the method is described by thermodynamic cycle steps.

[0196] 1 → 2: Liquefied LVPhC is pumped from the condenser and pressurized to a pressure P1 similar to or near the pressure in the mixing chamber in the nozzle.

[0197] 2 → 3: The liquefied LVPhC exchanges heat with the steam exiting the turbine and increases in temperature without changing phase (the high latent heat keeps the liquefied LVPhC liquid). Optionally, some of the LVPhC evaporates.

[0198] 3→4: Compressed liquid LVPhC (optionally partly vapor) is injected into an evaporator where it is evaporated. Optionally, this step occurs in a nozzle. 4→5: The compressed vapor LVPhC mixes with the HTL in a mixing chamber within the nozzle through which the HTL flows. The drop in static pressure and temperature associated with the flow within the nozzle causes a quasi-isothermal expansion, accelerating the LVPhC / HTL mixture and generating thrust at the nozzle exit, which rotates a turbine and produces electrical power, mechanical work, or another form of work. Optionally, the velocity of the mixture is supersonic in parts of the nozzle. 5 → 6: The high temperature vapor LVPhC leaves the nozzle separated from the HTL and flows to the heat exchanger where it does not change phase (the vapor remains vapor) and exchanges heat with the liquid LVPhC leaving the condenser. Optionally, some of the vapor is condensed. 6 → 1: The vapor is cooled in the condenser until it condenses and is compressed into a liquid.

[0199] The PV diagram for the thermodynamic cycle is shown in FIG.

[0200] Examples of LVPhC materials are antifreeze materials such as traditional ORC materials pentane, isobutane, propane, R134a, R245fa, fluorocarbons, and toluene.

[0201] FIG. 9 and the following listing show examples of controlled volume calculations for a thermodynamic cycle using biphasic pentane and ethylene glycol as the HTL.

[0202] Assuming 1 kg of pentane, the numbers in the TS diagram are P0 = 1 bar, P1 = 14.5 bar, T1 = 155°C, T HTL_cold = 35°C. 6→1: Condensation: 342KJ / Kg. 1 → 2: Isentropic compression of pumped LVPhC liquid to P1: 4KJ / Kg. 2 → 3a: LVPhC liquid exchanges heat with LVPhC vapor assuming a 30 degree gap: 146 KJ / Kg. 3a → 3: Additional heat from HTL reaches the liquid-vapor equilibrium point at P1: 144 KJ / Kg. 3 → 4: Evaporation of LVPhC liquid and heating of vapor to 155°C: 246KJ / Kg. 4→5: LVPhC steam expansion in nozzle isothermal work: 133KJ / Kg. 5→6: Cooling of steam in heat exchanger: 146KJ / Kg.

[0203] This calculation is the cycle efficiency

number

[0204] Assuming an ideal heat exchanger (temperature difference of 0°C) and ideal compressor and turbine, the efficiency reaches twice the Carnot efficiency compared to conventional ORC efficiency under similar conditions.

[0205] For two-phase nozzles, superheating is optional, and supercriticality (gas / liquid mixing) is also optional with a bubbly mixture flow within the nozzle. In this option, the line between points 3 and 5 in Figure 10 does not intersect the dotted bell-shaped line of the phase change.

[0206] Such engines typically require a heat source to vaporize the working fluid, accelerating the mixture in the nozzle and generating thrust to spin the turbine, followed by a condenser to cool and liquefy the vapor for reheating and reuse in the turbine.

[0207] In the case of a Carnot cell, the system includes a compressor / condenser that optionally isothermally compresses / condenses the vapor, an isothermal expansion / evaporation turbine, and a recuperator, with a countercurrent heat exchanger between them.

[0208] Figure 10A shows an optional charging process. The vapor LVPhC is condensed in a compressor / condenser powered by an external power source. The generated heat heats the HTL and the high-temperature reservoir. The hot liquid LVPhC then passes through a recuperator to cool it and reaches the turbine, where a pressure drop causes the liquid LVPhC to evaporate and expand in a nozzle, rotating the turbine and generating power that returns to the compressor. The cold LVPhC cools the low-temperature reservoir, passes through the recuperator, and returns to the compressor for an additional cycle. In this way, the work (power) invested in the compressor is converted to the high-temperature and low-temperature reservoirs.

[0209] In discharge mode, the turbine HTL is connected to the high-temperature reservoir, and the compressor / condenser is connected to the low-temperature reservoir HTL. Figure 10B shows the optional discharge process. Vapor LVPhC is condensed at the low-temperature reservoir temperature during compressor / condenser operation. The generated heat heats the HTL and low-temperature reservoir. The liquid LVPhC then passes through the recuperator, where it is heated, and reaches the turbine, where the heat and pressure drop causes the liquid LVPhC to evaporate and expand in the nozzle, rotating the turbine and generating electricity that is returned to the grid, some of which powers the compressor. The high-temperature vapor LVPhC cools the high-temperature reservoir, passes through the recuperator, and returns to the compressor for an additional cycle. In this way, work (electricity) is returned to the grid by using the high-temperature and low-temperature reservoirs.

[0210] Optionally, the isothermal compressor / condenser is a compressor with a nozzle as illustrated in Figure 4, which is a two-phase De Laval nozzle in an "inverse" configuration to increase the pressure of the gas and compress it isothermally by mixing it with HTL as described above, although it should be noted that this figure is not to scale.

[0211] An HTL, such as water, a low-freezing-point liquid, a hydrocarbon liquid, and / or other stream in the nozzle, enters the inlet at a pressure higher than ambient and exits the outlet at a pressure higher than ambient. A gas, such as air, hydrogen, or some other gas, is drawn into the HTL, compressed, cooled by the HTL, and emerges at the outlet at a pressure higher than ambient. While FIG. 4 shows an example of water as the HTL and air as the gas, the HTL may be selected from any suitable HTL, and the gas may be any suitable gas that is compressed. Optionally, the initial pressure and velocity of the HTL are generated by a pump. Optionally, the initial and final pressure values ​​of the HTL are identical to within 10%. Optionally, the initial and final pressures of the HTL are identical to within 20% or 30%.

[0212] Preferably, the operating temperature of the HTL is as low as possible. Optionally, below 100°C, 25°C, 15°C, or 0°C. Optionally, for a low-freezing-point HTL, the operating temperature is below −10°C, −25°C, or −50°C. Optionally, the HTL temperature is below −195°C if the HTL is liquid nitrogen, or below 4.2K if the HTL is liquid helium.

[0213] Optionally, such compressors can be used in a cascade configuration to reach higher pressures, whereby the compressed gas is fed into a second closed-loop compressor gas supply for a second pressure stage. For example, using water as the HTL and a supersonic nozzle, air is compressed to 15 bar in the first stage. This compressed air flows into a second supersonic nozzle in the second compressor closed loop, which is maintained at approximately 30 bar. At the nozzle, the pressure drops to below 15 bar, allowing the air to enter the nozzle. At the nozzle exit, the pressure rises to 30 bar, and the air is compressed while being cooled by water.

[0214] Optionally, the system is configured with pentane as the working fluid, or optionally cyclopentane for temperatures above 180°C. The HTL is, for example, ethylene glycol for operation up to 200°C, thermal oil for temperatures up to about 400°C, or molten salt for even higher temperatures. The optional working fluid can be any fluid used in a conventional ORC, such as pentane, isobutane, propane, R134a, R245fa, fluorocarbons, and toluene. For high temperatures, water can be used as the working fluid, similar to a Rankine cycle.

[0215] Figure 11 shows an example of temperature evolution during charging and discharging. In this example, a fixed low pressure (1 bar) and a fixed high pressure (14.5 bar) are reached in every cycle regardless of temperature. The reservoir temperatures at the start are, for example, 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).

[0216] Optionally, the final pressure reached by the turbine and compressor is set by the saturation pressure. This requires varying the pressure according to a temperature profile in this option, where the cold side is kept at a fixed temperature, but the hot reservoir is increased by varying the temperature of the reservoir. Figure 12 illustrates this option.

[0217] Optionally, any combination of fixed and variable pressures may be considered. For example, the system may be charged at variable pressure (FIG. 12, left side) while being discharged at constant pressure (FIG. 11, right side). Optionally, if the temperature of the cold reservoir is above ambient temperature, the cold reservoir or compressor / condenser may be thermally connected to the environment to maintain a lower temperature than would be achieved if the system were insulated. This increases the amount of power extracted.

[0218] Additionally, due to the inherently higher heat capacity of the working fluid in the liquid phase compared to the vapor phase, during the charging process, the liquid arrives at a higher temperature than the turbine, and during the discharging process, the liquid arrives at a lower temperature than the turbine. This reduces the overall round-trip efficiency by screening the temperature difference between the reservoirs. Because the overall net heat transfer to the liquid during a full charge-discharge cycle is zero, a high-heat-capacity material is optionally placed as part of the recuperator heat exchanger to act as a heat pendulum to supply the lost thermal energy. In the recuperator, the liquid phase exchanges heat with the vapor phase, while in the heat pendulum, only the liquid phase flows and exchanges heat with the thermal mass. Figure 13A shows the split recuperator (heat exchanger) and intermediate heat pendulum in the charging mode, where the temperature changes only minimally. In the charging mode, the heat pendulum heats up, cooling the liquid before reaching the turbine. Figure 13B shows the discharging mode, where the heat pendulum cools down, heating the liquid before reaching the turbine. The net energy in the pendulum is zero.

[0219] In general, the main advantage of the Carnot cell is its conversion into a heat engine configuration: once the heat storage is depleted, the discharge configuration becomes a heat engine, and the hot reservoir is replaced by combustion gases or hydrogen or any other combustion process. This allows the device to provide power all year round, even when the heat storage is depleted.

[0220] In an optional Carnot cell configuration, one reservoir can be ambient. The advantage is cost savings due to the elimination of one reservoir. In an optional system configuration, only the hot reservoir is used, and the cold reservoir is ambient. In this case, the working fluid is optionally pentane, cyclopentane, water, or any other working fluid used in a two-phase steam / HTL heat engine. Optionally, the HTL is ethylene glycol, thermal oil, molten salt, or other liquid that does not vaporize in the operating temperature and pressure range of the system. Optionally, in a discharge configuration, combustion gases, hydrogen, or other combustion processes can be used to heat the working fluid and HTL to generate power.

[0221] 17A is a block diagram illustrating a non-limiting embodiment of a system of the present disclosure in which the WF exchanges heat with the ambient in a condenser / evaporator. The system 100 includes a high-temperature HTL storage 102 (throughout this application, the term "high-temperature HTL storage" is interchangeable with the terms "high-temperature HTL storage" or "high-temperature HTL reservoir") selectively connected to a turbine 104 in a discharge mode and to a compressor 106 in a charge mode. When the high-temperature HTL storage 102 is fluidly connected to the turbine 104 or the compressor 106, it exchanges HTL with the respective components. In the charge mode, the HTL supplied to the compressor 106 has a lower temperature than the HTL returned from the compressor 106. In the discharge mode, the HTL supplied to the turbine 104 has a higher temperature than the HTL returned from the turbine 104.

[0222] In each mode of operation, the WF flows through a different closed-loop flow path.

[0223] In discharge mode, the WF flows in a first flow path from the turbine 104 to the counterflow heat exchanger 108, then to the condenser / evaporator 110 which acts as a condenser, back to the counterflow heat exchanger 108, and back to the turbine 104. In the flow path, after the WF condenses and before it enters the nozzle of the turbine 104, the WF is pressurized by a WF pump (not shown).

[0224] In the charging mode, the WF flows in a second flow path from the compressor 106 to the countercurrent heat exchanger 108, then to the condenser / evaporator 110, which functions as an evaporator, and back to the countercurrent heat exchanger 108 and back to the compressor 106. Typically, as the WF flows from the countercurrent heat exchanger 108 to the evaporator 110, the pressure of the WF is reduced, for example, by a dedicated pressure reducing nozzle, to reduce the temperature of the WF below ambient pressure so that it can pick up heat from the surroundings as it passes through the evaporator 110.

[0225] FIG. 17B is another block diagram illustrating a different, non-limiting embodiment of the disclosed system in which the WF exchanges heat with the ambient air in the condenser / evaporator. FIG. 17B differs from FIG. 17A in that the compressor 106 includes its own compressor HTL 107, which flows in a closed loop within the compressor 106, and does not receive high-temperature HTL from the high-temperature HTL reservoir 102. The compressor 106 further includes a compressor HTL reservoir 109 that stores the compressor HTL 107 before and / or after the compression process in the compressor. The compressor HTL reservoir 109 may be in the form of a chamber or may be a portion of the compressor HTL flow path within the compressor that is different from the operating zone where compression occurs. The compressor HTL gradually increases in temperature with each compression cycle of the WF, and the compressor is configured to exchange heat with the high-temperature HTL reservoir to heat it. The exchange of heat may be achieved by designing a portion of the compressor HTL closed-loop flow path to be thermally coupled to the high-temperature HTL reservoir or flow path of the high-temperature HTL without exchanging liquid 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 only thermally coupled to the HTL reservoir may be applied to any aspect of the present disclosure. Thus, in aspects that also include a low-temperature HTL reservoir, the compressor may be thermally coupled to the low-temperature HTL reservoir without exchanging liquid with it.

[0226] A more specific example of such a system configuration is shown in Figures 14A-14B, where during the discharge process (Figure 14A), the turbine is connected to a hot reservoir and to a condenser via a recuperator (surrounding the condenser is a cold reservoir). Optionally, the working fluid (WF) is cyclopentane. In this option, liquid WF is pressurized (pump intake), heated in the recuperator, and injected into the turbine, where it is further heated, vaporized, and quasi-isothermally expands, cooling the hot reservoir. The generated power drives the condenser, providing net output power. The vapor then travels to the recuperator, where it is cooled, condenses in the condenser, and returns to the recuperator. The process terminates when the temperature difference between the reservoirs becomes too small. The right side of Figure 14A shows a TS diagram of such a process. The different thermodynamic stages 3.0-5.0, 3.1-5.1, 3.2-5.2, 5.3-3.3 represent the evaporation and expansion of the hot reservoir as it rises in temperature as it is discharged (cooled) by the turbine.

[0227] In the charging process (FIG. 14B), the compressor / condenser is connected to a high-temperature reservoir and driven by external power. The WF vapor is compressed and condensed, during which heat flows from the WF to the high-temperature reservoir, raising the temperature of the high-temperature reservoir. The liquid WF is cooled in a recuperator. While the WF is cooled below ambient temperature, flash evaporation or other pressure reduction means is used to flash evaporate a portion of the WF. The WF continues to evaporate in the evaporator, while heat flows from the ambient to the WF. In this example, the evaporator is the same device as the condenser. The inlet vapor pressure at the compressor is the same as the pressure in the evaporator. It is controlled to allow evaporation at a saturation temperature lower than ambient temperature. The pressure reduction reduces the saturation temperature. The high-pressure liquid WF exiting the compressor passes through a pressure reduction nozzle, optionally an orifice, which reduces the pressure to the compressor inlet pressure level. As a result, the WF evaporates while being cooled to a temperature lower than ambient. This allows heat to flow from the ambient to the cooled WF, supporting further evaporation. The resulting WF vapor is near ambient temperature. The vapor is returned to the recuperator, where it is heated and compressed quasi-isothermally again in the compressor / condenser, heating the hot reservoir. Once the temperature is high enough, the process is complete.

[0228] An example system is a 250 kW Carnot Battery (CB) that optionally operates as a peaker gas turbine when storage is depleted.

[0229] The CB is evaluated by two parameters: engine efficiency and heat pump efficiency, known as the coefficient of performance (CoP). Ideally, when charging and discharging occur at the same temperature, these two parameters cancel each other out, allowing for 100% round-trip efficiency. In this solution, the engine and storage operate over a range of temperatures. At low temperatures (100°C < 140°C), a high CoP compensates for poor efficiency, while at high temperatures (140°C > 180°C), a high engine efficiency compensates for poor CoP. Table 1 shows the practical efficiency of a pentane turbine calculated by performing heat and mass balances (configuration of Figure 13A) at various temperatures. [Table 1]

[0230] FIG. 15A shows the heat and mass balance for a temperature of 140° C., showing an efficiency of 18.75%.

[0231] Figure 16 shows the enthalpy and entropy values ​​of pentane at various temperatures. The CoP in the charging process is determined by the heat pump in steps 5 to 3 of the temperature ramp, where Q = Tds, W = Q-dH, and CoP = Q / W.

[0232] As an example, consider two cases. Use CB as a standalone dispatchable power source. In this configuration, during charging, the pressure in the evaporator is set to 0.38 bar (saturation temperature T=10°C). This allows evaporation at ambient temperature. The compressor inlet pressure is 0.38 bar and the outlet pressure is slightly higher than the saturation pressure at the reservoir (and HTL in the compressor) temperature. In addition to the CB, an additional waste heat source of 75°C is used to heat the evaporator. With the 75°C waste heat, pentane is evaporated at 70°C and 2.8 bar pressure. Such an initial pressure reduces the work done in the 5-3 stage, but the latent heat extracted to the reservoir remains unchanged. With such an external waste heat source, the CoP and CB efficiency increase, optionally exceeding 100%.

[0233] Table 2 summarizes the extracted thermodynamic CoPs for Case 1 (ambient) and Case 2 (75°C) for various HTL temperatures. In reality, heat losses are recycled because the compressor is in the high-temperature section. If the compressor pump efficiency is 80% and the CoP is 4, the effective efficiency is 85% (0.8 + 0.2 / 4 = 0.85). The practical values ​​for an 80% pump efficiency are marked in bold in Table 2. It is clear that a waste heat source at 75°C more than doubles the CoP compared to ambient temperature. The overall round-trip efficiency (power output / power input) is the multiplication of the CoP and the discharge engine efficiency (Table 1). [Table 2]

[0234] Table 3 summarizes the return cycle efficiencies. [Table 3]

[0235] It is clear that a 75°C waste heat source provides an average round-trip efficiency of over 90%. In either case, once the heat store is exhausted, combustion gases or hydrogen powers the engine. Calculating the heat and mass balance for pentane at 250°C gives an efficiency of 30%.

[0236] To put it in perspective, Figure 15B shows the heat and mass balance for charging a 250 kW turbine at 140°C (system configuration as shown in Figure 14B). The heat and mass balance supports a round-trip efficiency of 84%. In this system configuration, the evaporator may be housed in an enclosure that receives waste heat. The enclosure may have an inlet for receiving the waste heat and an outlet for ventilating when a certain mass of waste heat is introduced.

[0237] Considering that waste heat at 75°C is quite common, providing 84% battery efficiency and 30% efficiency for peaker turbines would allow for the storage of excess generation from renewable energy-based power grids, thereby providing a baseload renewable energy grid and a major step towards full decarbonization. Another advantage is the decoupling of charging (compressor) and discharging (turbine). Renewable energy sources, such as solar and wind, can charge for a few hours per day but discharge nearly continuously. This requires large compressors and small turbines.

Claims

1. A system for storing and recovering energy in each charge and discharge operating mode, wherein the system is A high-temperature thermal conduction liquid (HTL) reservoir containing at least one high-temperature HTL reservoir, At least one two-phase turbine, and at least one two-phase compressor configured to compress a compressor HTL that is the same as or different from the high-temperature HTL of the high-temperature reservoir, Equipped with, In the discharge operation mode, the at least one high-temperature HTL reservoir is fluidly connected to the at least one two-phase turbine. In the charging operation mode, the at least one high-temperature HTL reservoir is fluidly connected or thermally coupled to the at least one two-phase compressor. The system is switchable between the discharge operation mode and the charge operation mode. The at least one high-temperature HTL reservoir is fluidly connected to the at least one two-phase turbine, or fluidly connected or thermally coupled to the at least one two-phase compressor, for the following purposes: (1) to supply high-temperature HTL to each turbine in the discharge mode, or (2) in the charging mode, if the compressor HTL and the high-temperature HTL are different and the compressor HTL reservoir and the high-temperature HTL reservoir are different, to exchange heat between the compressor HTL or compressor HTL reservoir and the HTL of the high-temperature reservoir, or if the compressor HTL and the high-temperature HTL are the same and the compressor HTL reservoir and the high-temperature HTL reservoir are the same, to supply high-temperature HTL to the at least one compressor. The system further comprises at least one condenser and at least one evaporator. The at least one condenser is in fluid communication with the turbine to receive and condense the working fluid (WF) flowing in from the turbine. The at least one evaporator is in fluid communication with the at least one compressor to receive and evaporate WF flowing in from the at least one compressor, and the at least one evaporator is the same as or different from the at least one condenser. The discharge mode defines a first flow path of the water flow (WF), and the charging mode defines a second flow path of the WF. By switching between the discharge operation mode and the charging operation mode, the flow of the WF is switched between the first flow path and the second flow path, respectively. In a discharge mode, the WF flows in the first flow path from the at least one condenser to one or more nozzles in the at least one turbine, the nozzles are configured to mix the WF and the HTL in the one or more nozzles to form an HTL / WF mixture by inducing rotation of the turbine when discharging the fluid, therein the WF undergoes quasi-isothermal expansion, thereby lowering the temperature of the HTL and accelerating and discharging the HTL / WF mixture through the one or more nozzles, the HTL / WF mixture discharged from the one or more nozzles is received in at least one first separation zone configured to separate the WF from the HTL, the HTL is recirculated to the at least one high-temperature reservoir or the one or more nozzles, the separated WF flows into the condenser to undergo condensation and is received, and the condensed WF is discharged from the at least one condenser and returned to the turbine.

2. The system according to claim 1, comprising at least one first counterflow heat exchanger positioned between the at least one turbine and the at least one condenser in the first flow path and configured for heat exchange between WF coming out of the at least one turbine and WF coming out of the at least one condenser, wherein the heat exchanger is configured to lower the temperature of the WF flowing from the turbine to the condenser.

3. The system according to claim 1 or 2, further comprising at least one pressurization configuration configured to pressurize or propel the WF after it has been condensed in the at least one condenser.

4. The system according to claim 1, wherein in the charging mode, the at least one high-temperature HTL reservoir is fluidly connected or thermally coupled to the at least one two-phase compressor, the WF flows through the second flow path, the at least one compressor is configured to form a compressor HTL / WF mixture and heat the compressor HTL by quasi-isothermally compressing the WF in the mixture along the compressor flow path, the compressor HTL heats the high-temperature HTL reservoir by exchanging heat with the high-temperature HTL reservoir and is circulated to the same or a different reservoir as the high-temperature HTL reservoir, or circulated within the at least one compressor, the compressed WF is discharged from the at least one compressor and received by the evaporator for evaporation, the evaporated WF is discharged from the at least one evaporator and returned to the at least one compressor.

5. The system according to claim 4, further comprising at least one second counterflow heat exchanger positioned between the at least one compressor and the at least one evaporator in the second flow path and configured for heat exchange between WF coming out of the at least one compressor and WF coming out of the at least one evaporator, wherein the heat exchanger is configured to raise the temperature of the WF flowing from the compressor to the turbine.

6. The system according to claim 4, further comprising at least one depressurizing nozzle positioned 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.

7. The system according to any one of claims 4 to 6, wherein the WF is a liquid-to-vapor phase transition (LVPhC) WF, selected to be (i) vapor phase when (1) entering the at least one compressor, (2) after being mixed with the HTL in the at least one turbine and in thermal equilibrium, and (3) when exiting the at least one evaporator, and (ii) liquid phase when (4) exiting the at least one condenser and (5) exiting the at least one compressor.

8. The system according to claim 4, wherein the at least one evaporator and the at least one condenser are the same element.

9. The system according to claim 5, wherein the system further comprises at least one first counterflow heat exchanger positioned between the at least one turbine and the at least one condenser in the first flow path and configured to exchange heat between WF coming out of the at least one turbine and WF coming out of the at least one condenser, the at least one first counterflow heat exchanger and the at least one second counterflow heat exchanger being the same one or more elements that can be selectively connected to the at least one turbine or the at least one compressor in their respective discharge or charge modes.

10. The system according to claim 4, further comprising one or more selection valves for enabling the selective connection of the at least one high-temperature HTL reservoir to the at least one compressor and the at least one turbine.

11. The system according to claim 4, wherein the HTL is selected from a list consisting of antifreeze, water, brine, heat transfer oil, molten salt, ethylene glycol, and liquid phase WF.

12. The aforementioned WF is air, nitrogen, CO ２ The system according to claim 4, selected from the list consisting of ammonia, propane, ORC phase change material, pentane, and cryogenic phase change material.

13. The system according to claim 4, further comprising at least one external heat source for enabling controllable heating of the HTL.

14. The system according to claim 4, wherein the at least one condenser and the at least one evaporator are each configured to exchange heat with the surroundings for condensation and evaporation.

15. The system according to claim 4, wherein the at least one evaporator is configured for heating by at least one external heat source in the charging operation mode.

16. The system according to claim 4, wherein the inlet compressor pressure of the WF and the pressure of the WF in the evaporator are lower than the critical pressure at a temperature lower than the ambient temperature, thereby enabling the evaporation of the WF and the flow of heat from the surroundings to the WF vapor.

17. The system according to claim 2 or 9, wherein the at least one first heat exchanger comprises at least one first thermal pendulum, the at least one first thermal pendulum being a high heat capacity body configured to exchange heat with mass passing through the at least one first heat exchanger, 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, and the flow path of water flow between the first heat exchanger section and the second heat exchanger section passes through the thermal pendulum.

18. The system according to claim 5 or 9, wherein the second heat exchanger comprises a second thermal pendulum, the second thermal pendulum being a high-heat-capacity body configured to exchange heat with mass passing through the second heat exchanger, and 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, and the flow path of water flow between the first heat exchanger section and the second heat exchanger section passes through the second thermal pendulum.

19. The system according to claim 17, wherein the second thermal pendulum is the same as the first thermal pendulum.

20. The system according to claim 4, wherein the first flow path and the second flow path are closed-loop flow paths.

21. The system according to claim 4, wherein the at least one turbine is configured to increase the pressure of the HTL to obtain high-pressure HTL, introduce the high-pressure HTL into one or more nozzles and mix it with WF at substantially the same pressure to form an HTL / WF mixture, and thereafter the HTL / WF mixture is accelerated toward the outlet of one or more nozzles by the quasi-isothermal expansion of the WF in one or more nozzles.

22. The system according to claim 4, wherein the at least one compressor comprises an HTL pump for increasing the HTL pressure, the HTL pump is fluidly coupled to a compressor nozzle configured to receive pressurized HTL from the HTL pump and mix it with WF in the nozzle to obtain an HTL / WF mixture, the HTL / WF mixture being discharged from the nozzle at a pressure higher than the pressure of the WF introduced into the compressor.

23. The system according to claim 4, wherein the at least one WF pump is provided within the at least one condenser.

24. The system according to claim 1, wherein the evaporator is maintained at a temperature higher than the ambient temperature.

25. The system according to claim 1, wherein the compressor HTL, unlike the high-temperature HTL, flows through a closed loop within the compressor and thermally exchanges heat with the high-temperature HTL reservoir in the charging mode.

26. The system according to claim 1, wherein the compressor HTL is the same as the high-temperature HTL, the compressor HTL reservoir is the same as the high-temperature HTL reservoir, and in the charging mode, the high-temperature HTL reservoir is fluidly connected to the at least one two-phase compressor to supply the high-temperature HTL to the at least one compressor.

27. A system for converting electrical energy into heat and recovering the stored heat into electrical energy, wherein the system is The system described in claim 1, In the discharge operation mode, at least one generator rotatably coupled to the at least one turbine for generating power, To operate the compressor and heat-fill the at least one high-temperature reservoir, at least one electric motor is rotatably coupled to the at least one compressor, A system equipped with these features.

28. A method for storing and recovering energy in each charge and discharge operating mode, the method comprising providing a system, the system is A high-temperature thermal conduction liquid (HTL) reservoir containing a high-temperature HTL, At least one two-phase turbine, and at least one two-phase compressor configured to compress a compressor HTL that is the same as or different from the high-temperature HTL of the high-temperature reservoir, Equipped with, The at least one high-temperature HTL reservoir is selectively configured to (1) supply high-temperature HTL to each turbine in the discharge mode, or (2) in the charging mode, if the compressor HTL and the high-temperature HTL are different and the compressor HTL reservoir and the high-temperature HTL reservoir are different, to exchange heat between the compressor HTL or the compressor HTL reservoir and the HTL of the high-temperature reservoir, or if the compressor HTL and the high-temperature HTL are the same and the compressor HTL reservoir and the high-temperature HTL reservoir are the same, to supply high-temperature HTL to the at least one compressor, by (i) being fluidly connectable to the at least one two-phase turbine in the discharge operation mode, and (ii) being fluidly connectable or thermally coupled to the at least one two-phase compressor in the charging operation mode. The system further comprises at least one condenser and at least one evaporator. The at least one condenser is in fluid communication with the turbine to receive and condense the working fluid (WF) flowing in from the turbine. The at least one evaporator is in fluid communication with the at least one compressor to receive and evaporate WF flowing in from the at least one compressor, and the at least one evaporator is the same as or different from the at least one condenser. The discharge mode defines a first flow path of the WF, and the charging mode defines a second flow path of the WF. The method described above, in the discharge mode, The high-temperature HTL reservoir is coupled to the at least one two-phase turbine, By flowing the WF from the at least one condenser through the first flow path to one or more nozzles in the at least one turbine, the WF and HTL are mixed in the one or more nozzles to form an HTL / WF mixture, where the WF undergoes quasi-isothermal expansion, thereby lowering the temperature of the HTL, and accelerating the HTL / WF mixture and discharging the mixture through the one or more nozzles, thereby inducing rotation of the turbine when the fluid is discharged. The HTL / WF mixture discharged from one or more nozzles is received in at least one first separation zone for separating the WF from the HTL, Recirculating the HTL to the at least one high-temperature reservoir or the one or more nozzles, The separated WF is to flow into the condenser, be received, and undergo condensation. The condensed WF discharged from at least one of the condensers is returned to the turbine, Equipped with, The method comprises, in the charging mode, fluidly connecting or thermally coupling the at least one high-temperature HTL reservoir to at least one two-phase compressor, and flowing the WF into the second flow path.

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