Two-phase heat engine

Abstract

The present disclosure provides a system and method for generating work. The system and method provide a unique implementation of the Ericsson cycle. In the solution of the present disclosure, HTL is mixed with a gas, and both reach approximately the same temperature following their mixing. The HTL and the gas are mixed at approximately the same pressure and the mixture together undergoes an expansion from a first pressure to a second pressure lower than the first pressure within a nozzle. Since the HTL has a much higher heat capacity and the gas is surrounded by the HTL during expansion, the HTL continuously heats the gas during expansion, resulting in an isothermal or quasi-isothermal expansion within the nozzle. The expansion of the gas results in an acceleration of the mixture within the nozzle, and the kinetic energy of the accelerated mixture is converted into work either by using the nozzles within a reaction turbine or by using the discharged mixture to drive a turbine, such as an impulse turbine. When implementing the invention in a reaction turbine, the non-zero velocity of the HTL / gas mixture at the outlet of the nozzle is used to separate the mixture by forming a film flow on a circular frame, and the film flow experiences centrifugal force by the frame. The discharged gas is cooled within a heat exchanger, such as a reheater, and recompressed while being at a low temperature within a compressor. The compressed gas is then heated within a heat exchanger (reheater) before returning to the turbine. The discharged HTL is collected and undergoes another cycle within the turbine. A portion of the HTL is reheated by passing through an additional heat exchanger having a heat source.

Description

Technical Field

[0001] The present disclosure relates to the field of heat engines, specifically, heat engines based on mixtures of two materials in different phases respectively.

Background Art

[0002] References considered relevant as background to the subject matter of the present disclosure are listed below. - International Publication No. 2022 / 049573

[0003] The approval of the above references in this specification should not be construed as meaning that they are in any way relevant to the patentability of the subject matter of the present disclosure.

Summary of the Invention

[0004] The present disclosure provides a system and method for generating work. The system and method provide a unique implementation of the Ericsson cycle. In the solution of the present disclosure, the HTL is mixed with a gas, and both reach the same temperature following their mixing. The HTL and the gas are mixed at approximately the same pressure, and they undergo an expansion from a first pressure to a second pressure lower than the first pressure together as a mixture within a nozzle. The HTL has a much higher heat capacity, and since the gas is surrounded by the HTL during expansion, the HTL continuously heats the gas during expansion, resulting in an isothermal or quasi-isothermal expansion within the nozzle. The expansion of the gas causes an acceleration of the mixture within the nozzle, and the kinetic energy of the accelerated mixture is converted into work either by using the nozzles within a reaction turbine or by using the discharged mixture to drive a turbine, such as an impulse turbine. For efficiency, the solution of the present invention is suitable for use in a reaction turbine. The reaction turbine achieves a high static pressure with minimal head loss. Also, in a reaction turbine, the non-zero velocity of the HTL / gas mixture at the outlet of the nozzle is used to separate the mixture by forming a film flow on a circular frame, and the film flow experiences centrifugal force by the frame. Finally, the reaction turbine avoids cavitation that occurs in an impulse turbine. The discharged gas is cooled within a heat exchanger, such as a reheater, and recompressed while at a low temperature within a compressor. Optionally, the compression within the compressor is isothermal compression or quasi-isothermal compression. The compressed gas is then heated within a heat exchanger (reheater) before returning to the turbine. The discharged HTL is collected and undergoes another cycle within the turbine. A portion of the HTL is reheated by passing through an additional heat exchanger having a heat source.

[0005] Accordingly, a first aspect of the present disclosure provides a method for generating work. The method includes heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering the HTL to an inlet of a nozzle at approximately the first pressure. The method further includes compressing a gas by a compressor to approximately the first pressure and heating the compressed gas within a heat-receiving portion of a heat exchanger to a temperature that is approximately below the first temperature but higher than approximately the second temperature, i.e., to a temperature between approximately the second temperature and approximately the first temperature. The term "approximately" should be construed as a deviation of up to 20%. For example, if a first material is compressed to approximately the pressure of a second material, the first material should be construed as being within 20% of the nominal pressure value of the second material. The same applies to temperature. It should be noted that in the context of implementing the method or system of the present disclosure, since the gas that transfers heat is at the first temperature, the gas cannot be heated above the first temperature only by receiving heat from the heat exchanger. The method further includes mixing the HTL at the first pressure and the first temperature within the nozzle with the compressed gas at approximately the first pressure and at approximately below the first temperature to obtain a mixture of the gas and the HTL. It should be noted that the gas can be mixed with the HTL when it has a temperature lower than approximately the first temperature. Accordingly, following the mixing, if the gas is at a temperature lower than approximately the first temperature, it is heated to approximately the first temperature by the HTL. This method further enables the gas in the mixture to undergo an isothermal or quasi-isothermal expansion to a second pressure lower than the first pressure within the nozzle, thereby accelerating the mixture towards the outlet of the nozzle. The method further includes discharging the mixture through the outlet to generate mechanical work, separating the mixture, introducing the discharged gas into a heat-removing portion of the heat exchanger to exchange heat with the compressed gas exiting the compressor, and directing the discharged HTL through another cycle towards the heating volume.

[0006] In some embodiments of the method, the compression includes isothermal compression or near-isothermal compression of the gas.

[0007] Another method aspect of the present disclosure provides a method for implementing a heat engine. The method includes: (i) introducing a heat transfer liquid (HTL) into a nozzle at a first pressure and a first temperature; (ii) isothermally compressing a gas by a compressor from a second pressure and a second temperature, where the second pressure and temperature are lower than the first pressure and the first temperature respectively, to the first pressure; (iii) heating the compressed gas exiting the isothermal compressor at the first pressure and the second temperature to be approximately below the first temperature but higher than the second temperature by passing it through the heat-receiving portion of a counter-flow heat exchanger; (iv) injecting the heated gas exiting the heat-receiving portion of the heat exchanger into the nozzle to obtain a mixture of HTL and gas, thereby isothermally or near-isothermally expanding the mixture to the second pressure, resulting in acceleration of the mixture within the nozzle; (v) discharging the accelerated mixture from the outlet of the nozzle; and (vi) recovering the gas discharged at approximately the second pressure and approximately the first temperature in the heat-removing portion of the heat exchanger for heat exchange with the compressed gas exiting the compressor.

[0008] In some embodiments of the method, the gas introduced into the heat exchanger following its discharge from the nozzle is repeatedly isothermally or near-isothermally compressed, thereby forming a closed-loop flow of the gas. That is, the high-temperature gas discharged from the nozzle passes through the heat exchanger, exchanges heat with the compressed gas exiting the cooler and the compressor, and then the gas is directed to undergo isothermal or near-isothermal compression by the compressor as part of a closed-loop operation.

[0009] Note that any combination of the embodiments described with respect to any aspect of the present disclosure is applicable. In other words, any aspect of the present disclosure can be defined by any combination of the described embodiments. In particular, any of the following embodiments of the method is applicable to any of the above method aspects.

[0010] In some embodiments of the method, delivering or introducing the HTL to the nozzle includes pressurizing the HTL to approximately the first pressure. After the HTL is discharged from the nozzle, it is at approximately the second pressure. Therefore, in order to go through another cycle, it is necessary to pressurize the HTL to approximately the first pressure. This may be done by a pump pressurization unit, or, if the method is implemented in a reaction turbine, the centrifugal force of the turbine forms a suction condition and effectively forms a pump that raises the pressure of the HTL to approximately the first pressure. In some embodiments of the method, the gas entering the compressor is air under ambient conditions, and the gas exiting the heat exchanger after heat removal, i.e., the gas entering the high-temperature heat exchanger and exiting the heat exchanger at a lower temperature, is discharged to the surroundings.

[0011] In some embodiments of the method, the HTL is selected from the list consisting of molten salt, thermal oil, ethylene glycol, water, molten metal, or any combination thereof.

[0012] In some embodiments of the method, the gas is one from the list consisting of air, nitrogen, argon, or any combination thereof.

[0013] In some embodiments, the method further includes monitoring the HTL temperature. The method further includes controllably discharging the gas from a compressed gas storage unit that stores compressed gas at approximately the first pressure and approximately the second temperature to the heat receiving portion. The controllable discharge of the gas is performed based on the HTL temperature to obtain a certain output power.

[0014] In some embodiments, the method further includes monitoring the HTL temperature. The method further includes controllably discharging gas from a compressed gas storage unit that stores compressed gas at approximately the first temperature and approximately the first pressure to a location in the gas flow path between the heat exchanger and the nozzle or turbine. That is, the compressed gas storage unit stores high-temperature compressed gas provided at a location downstream of the heat-receiving portion of the heat exchanger when necessary. The controllable discharge of the gas is performed based on the HTL temperature to obtain a constant output power.

[0015] In some embodiments, the method further includes supplying compressed gas to the compressed gas storage unit following compression by a compressor. This is typically done in the start-up process of a method of initially filling the compressed gas storage unit, if necessary, i.e., due to a change in the temperature of the HTL, with either high-temperature or low-temperature compressed gas for later use.

[0016] In particular, when the HTL temperature decreases below the desired operating temperature, it results in a decrease in thermal expansion along with heating, and thus a lower volumetric flow rate enters the nozzle and is mixed with the HTL. To maintain a constant output power, compensation for additional gas to the cycle is required, which is implemented by controlling a valve that is controllably opened and closed based on the temperature of the HTL.

[0017] In some embodiments of the method, the stored gas is at approximately the first pressure and approximately the second temperature. The controllable discharge of the gas from the compressed gas storage unit is performed downstream of the heat-receiving portion and upstream of or at the nozzle.

[0018] In some embodiments of the method, the compressed stored gas is at approximately the second temperature, and the volumetric flow rate from the compressed gas storage unit is

[0019]

Number

[0020]

Number

[0021] In some embodiments of the method, the compressed storage gas is at approximately the first pressure and approximately the first temperature. The controllable release of gas from the gas storage is carried out within the location of the flow path between the end of the heat-receiving part and the nozzle.

[0022] In some embodiments, the method further includes maintaining a constant volumetric flow rate of the gas within the nozzle along the range of the HTL operating temperature after the gas is heated to the HTL temperature and before the pressure decreases.

[0023] In some embodiments, the method further includes maintaining equal static pressure at the inlet of the nozzle, or in the mixing region of the nozzle where the HTL is mixed with the gas, and at the proximal end portion of the outlet region within the nozzle downstream of the mixing region. In some embodiments, the equal static pressure is higher than 50% of the stagnation pressure.

[0024] In some embodiments of the method, the first temperature, the first pressure, the second temperature, the second pressure, and the flow rate are within 30% of their nominal values. That is, there can be a deviation of these values up to 30% at most.

[0025] In some embodiments of the method, the discharging results in rotation of the nozzle, thereby generating work.

[0026] In some embodiments of the method, the nozzle is part of a reaction turbine, and the nozzle is part of a turbine positioned at the periphery of an impeller where the static pressure and the stagnation pressure are the highest.

[0027] In some embodiments of the method, the discharging is performed at a non-zero velocity that forms a film flow on the surface being injected. The film flow on the surface results in the separation of the gas and the HTL.

[0028] In some embodiments, the method further includes separating the HTL from the gas following the discharging.

[0029] In some embodiments of the method, the separating includes directing the discharged mixture onto a curved surface. The collision or engagement of the mixture of the gas and the HTL with the curved surface results in a flow on the surface that experiences a centrifugal force. This results in the separation of the HTL and the gas.

[0030] In some embodiments, the method further includes recovering a portion of the discharged HTL into a nozzle for another cycle.

[0031] In some embodiments of the method where the turbine is a reaction turbine, the recovering is performed due to the operation of the reaction turbine that results in the suction of the HTL into the nozzle.

[0032] In some embodiments of the method, the heat exchanger is a reheater.

[0033] In some embodiments of the method, the first pressure is above about 8, 9, 10, 11, or 12 Bar and the first temperature is above about 100 °C.

[0034] In some embodiments of the method, the flow of the mixture within the nozzle is a supersonic flow.

[0035] In some embodiments of the method, the second pressure is the ambient pressure.

[0036] In some embodiments of the method, the second temperature is the ambient temperature.

[0037] Yet another aspect of the present disclosure provides a system for generating work. The system includes a heating volume to enable heating a heat transfer liquid (HTL) to a first temperature by a heat source. A pump of the system is configured to raise the pressure of the HTL to a first pressure at the first temperature. The pump can be positioned at various locations within the system. For example, the pump can be downstream or upstream of the heating volume. Optionally, the inherent centrifugal force of a reaction turbine is used as a pump for at least a portion of the HTL. At least a portion of this HTL is pumped as a result of conditions that cause the reaction turbine to be induced and (as described below) sent from a drain to a nozzle while raising its pressure from approximately a second pressure to approximately a first pressure. If the pump formed by the reaction turbine is the only pump within the system, the startup process of the system requires external intervention, such as a driver that causes an initial operation of the system, e.g., a pump that causes a first cycle of the system. The system further includes a compressor, e.g., an isothermal compressor, configured to compress a gas to approximately the first pressure. The system is in fluid communication with the compressor and includes a heat exchanger configured to receive the compressed gas at its heat-receiving portion and enable heat transfer to the compressed gas to increase the temperature of the compressed gas to be below approximately the first temperature but higher than approximately the second temperature. The system further includes a nozzle in fluid communication with the heat exchanger and the HTL pump, the nozzle having an inlet portion for receiving the HTL and a mixing portion that (i) enables mixing the HTL at approximately the first temperature and approximately the first pressure with the gas at approximately the first temperature and approximately the first pressure to obtain a mixture, and (ii) enables the mixture to undergo an isothermal expansion to a second pressure lower than the first pressure, thereby accelerating the mixture in the nozzle toward the outlet of the nozzle. The system further includes a turbine, e.g., a reaction turbine connected to or being part of the nozzle configured to rotate as a result of the acceleration of the mixture, thereby converting the kinetic energy of the mixture into work. The system further includes a separation unit for separating the gas and the HTL.The separation unit comprises a collection unit for collecting the discharged HTL and directing it to either the inlet of the heating volume, the pump, or the nozzle for passing through another cycle without reheating it. Since the volumetric heat capacity of HTL is about 100 times higher than that of the gas, the heat transfer from HTL to gas during isothermal expansion in the nozzle only slightly reduces the HTL temperature. Therefore, the HTL can proceed through several cycles in the nozzle before being required to be reheated again. Thus, the system can be designed such that the HTL accumulating in the collection unit is partially directed to either the heating volume or the pump, depending on their order in the system flow path which can be varied in different implementations of the system, and a portion of it is directed to return to the nozzle to pass through another cycle. The discharged gas is directed to the heat removal part of the heat exchanger to exchange heat with the compressed gas in the heat receiving part flowing out of the compressor.

[0038] In some embodiments of the system, the cooled gas exiting the heat removal part of the heat exchanger flows towards the compressor, thereby forming a closed loop flow of the gas.

[0039] In some embodiments of the system, the cooled gas exiting the heat removal part of the heat exchanger flows to the surroundings, and the compressor is configured to receive the gas from the surroundings and compress the gas to approximately the first pressure, thereby forming an open system.

[0040] In some embodiments of the system, the HTL is selected from the group consisting of molten salt, heat transfer oil, molten metal, ethylene glycol, water, or any combination thereof.

[0041] In some embodiments of the system, the gas is selected from the group consisting of air, nitrogen, argon, or any combination thereof.

[0042] In some embodiments, the system further comprises a compressed gas storage unit that stores compressed stored gas at approximately the first pressure and is in fluid communication with a flow path portion between the compressor and the heat receiving portion. The compressed gas storage unit is configured to controllably release gas based on the sensed temperature of the HTL to obtain either (i) a constant volumetric flow rate injection into the nozzle or (ii) a constant output power.

[0043] In some embodiments, the system further comprises a compressed gas storage unit that stores compressed gas at approximately the first pressure and approximately the first temperature and is in fluid communication with a flow path portion between an end of the heat receiving portion and the nozzle. That is, the high-temperature compressed gas from the compressed gas storage unit is in fluid communication with a portion of the flow path downstream of the heat receiving portion of the heat exchanger and upstream of the nozzle, or sometimes with the nozzle itself. The gas storage unit is configured to controllably release gas based on the sensed temperature of the HTL to obtain either (i) a constant volumetric flow rate injection into the nozzle or (ii) a constant output power.

[0044] It should be noted that in some embodiments, the compressed gas storage unit is mainly configured to be filled with compressed gas compressed by the compressor of the system. Following the compression of the gas by the compressor, the gas is directed to fill the compressed gas storage unit either in a hot state or a cold state, i.e., after or before passing through the heat exchanger. Thus, the initial setup of the system may include filling this compressed gas storage unit to enable efficient operation of the system.

[0045] In particular, when the HTL temperature decreases below the desired operating temperature, it results in a decrease in thermal expansion with heating, and thus a lower volumetric flow rate enters the nozzle and is mixed with the HTL. To maintain a constant flow rate and thus a constant output power, compensation with additional gas to the cycle is required, which is achieved by controlling a valve that is controllably opened and closed based on the temperature of the HTL.

[0046] In some embodiments, the system further comprises a temperature sensor configured to sense the temperature of the HTL at at least one location along the flow path of the HTL, generate HTL temperature data based thereon, and transmit the HTL temperature data to a controller of the compressed gas reservoir to control a valve for performing the controllable release.

[0047] In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL at a location along the flow path of the HTL between its discharge from the nozzle and the inlet of the nozzle, i.e., the temperature of the HTL where the HTL enters the nozzle. Any location along the flow path defined above is suitable for performing the sensing of the temperature of the HTL.

[0048] In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL at at least one location along the flow path of the HTL between the discharge of the HTL from the nozzle and the introduction of the HTL into the nozzle.

[0049] In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL within the collection unit. That is, the temperature sensor senses the temperature of the HTL accumulated within the collection unit.

[0050] In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL in an HTL drain that receives the HTL after the discharge of the HTL from the nozzle.

[0051] In some embodiments of the system, the compressed gas is at approximately the first pressure and approximately the second temperature. The compressed gas reservoir is in fluid communication with the heated portion or a portion upstream thereof. That is, the compressed gas reservoir is connected to a portion of the flow path between the compressor and the heated portion of the heat exchanger.

[0052] In some embodiments of the system, the compressed stored gas is at approximately the second temperature, and the volumetric flow rate from the compressed gas reservoir is

[0053] [Number] in accordance with, where T HTL is the temperature of the HTL,

[0054] [Number] is the volumetric flow rate of the gas entering the nozzle, and the temperature is in Kelvin units.

[0055] In some embodiments of the system, the compressed gas is at approximately the first pressure and approximately the first temperature. The compressed gas storage is in fluid communication with the heat removal section or downstream thereof. That is, the hot compressed gas from the compressed gas storage is in fluid communication with a portion of the flow path downstream of the heat receiving portion of the heat exchanger and upstream of the nozzle, or sometimes with the nozzle itself.

[0056] In some embodiments of the system, the compressed gas storage includes a controller configured to maintain a constant volumetric flow rate of the gas within the nozzle along the range of HTL operating temperatures.

[0057] In some embodiments of the system, the nozzle is configured to maintain equal static pressure at the inlet of the nozzle, or at the mixing volume of the nozzle where the gas and HTL are mixed, and at the proximal end of the outlet region downstream of the mixing volume. In some embodiments, the static pressure is higher than 50% of the stagnation pressure.

[0058] In some embodiments of the system, the first temperature, first pressure, second temperature, second pressure, and flow rate are within a range of 30% of their nominal values. That is, there can be a deviation of these values up to a maximum of 30%.

[0059] In some embodiments of the system, the heat source is solar radiation, and the heating volume is configured to receive heat from the solar radiation and transfer it to the HTL.

[0060] In some embodiments of the system, the pump is disposed downstream of the nozzle and upstream of the heating volume.

[0061] In some embodiments of the system, the pump is disposed downstream of the heating volume and upstream of the nozzle.

[0062] In some embodiments of the system, the nozzle comprises the heating volume.

[0063] In some embodiments of the system, the nozzle comprises a part defined by a de Laval nozzle supersonic convergent-divergent portion, i.e., an asymmetric hourglass shape. The de Laval nozzle portion is defined between a proximal end and a distal end, and the de Laval nozzle portion is defined downstream of the mixing portion. An optional advantage of the supersonic de Laval nozzle is its high efficiency and high output power due to the high mass ratio of the gas / HTL mixture compared to a subsonic nozzle.

[0064] In some embodiments of the system, the de Laval nozzle cross-section has a circular geometry.

[0065] In some embodiments of the system, the cross-section of the de Laval nozzle has a rectangular geometry with rounded corners.

[0066] In some embodiments of the system, the proximal ends of the inlet portion, the mixing portion, and the de Laval nozzle portion all have approximately the same maximum cross-sectional area. Each maximum cross-section pf of these portions is defined on a plane perpendicular to the flow direction, i.e., on an approximately same maximum horizontal cross-section forming a circular shape. It should be noted that in the context of similar cross-sections, the term "approximately" means a deviation of up to 20% from the nominal cross-sectional area value. Typically, the maximum cross-section of the mixing portion is slightly larger than the maximum cross-section of the inlet portion due to the additional volume of the injected gas.

[0067] In some embodiments of the system, the maximum cross-section of the mixing portion is up to 20% larger than the maximum cross-section of the inlet portion.

[0068] In some embodiments of the system, the maximum cross-section of the mixing portion is common with the maximum cross-section of the proximal end. That is, the maximum cross-section of the mixing portion is found at the most downstream portion in contact with the proximal end.

[0069] In some embodiments of the system, the turbine comprises the nozzle described above, and the nozzle rotates with the impeller to generate work. That is, the discharge of the accelerated mixture through the nozzle rotates the nozzle, resulting in the generation of work, which is used to generate electricity by rotation.

[0070] In some embodiments of the system, the turbine is a reaction turbine.

[0071] In some embodiments of the system, the collection unit defines a drain for accumulating the separated HTL. A portion of the HTL is suctioned from the drain to the nozzle, resulting in an increase in the HTL pressure from approximately the second pressure to approximately the first pressure due to the operation of the reaction turbine. That is, there is a duct connecting the nozzle and the drain, and the discharge of the mixture through the nozzle creates suction conditions that result in an increase in the HTL pressure to approximately the first pressure and its delivery to the nozzle or the inlet of the nozzle.

[0072] In some embodiments of the system, the separation unit comprises a curved or circular frame through which the mixture is discharged. The engagement of the mixture with the curved or circular frame results in a film flow on the surface of the curved or circular frame. The flow on the surface experiences the centrifugal force applied by the frame, which results in the separation of the HTL and the gas.

[0073] In some embodiments of the system, the heat exchanger is a reheating device.

[0074] In some embodiments of the system, a part of the reaction turbine forms the pump described above.

[0075] In some embodiments of the system, the pump is disposed or defined between the drain and the nozzle. That is, the pump is defined downstream of the drain and upstream of the nozzle. The centrifugal force generated by the reaction turbine actually acts as a pump that pumps the HTL from the drain and delivers it to the nozzle while raising the pressure of the HTL from approximately the second pressure to approximately the first pressure, inducing suction conditions that cause the HTL to flow.

[0076] In some embodiments of the system, the first pressure exceeds about 8, 9, 10, 11, or 12 Bar, and the first temperature exceeds about 100 °C.

[0077] In some embodiments of the system, the second pressure is the ambient pressure.

[0078] In some embodiments of the system, the second temperature is the ambient temperature.

[0079] In some embodiments of the system, the flow of the mixture within the nozzle is a supersonic flow.

[0080] Any one or any combination of the above embodiments of the system can be used in the method according to any one or any combination of the above embodiments of the method.

[0081] Yet another aspect of the present disclosure provides a nozzle for use in a heat engine. The nozzle includes an inlet portion for receiving a heat transfer fluid, a mixing portion for mixing the received HTL with a gas, and a de Laval nozzle portion, i.e., a portion defined by an asymmetric hourglass shape defined between a proximal end and a distal end. The de Laval nozzle portion is defined downstream of the mixing portion, and the mixing portion is defined downstream of the inlet portion. The de Laval portion is configured to allow for an isothermal expansion of the gas between a first pressure and a second pressure lower than the first pressure.

[0082] In some embodiments, the nozzle further comprises an injection port for enabling injection of gas into the mixing portion.

[0083] In some embodiments of the nozzle, the proximal ends of the inlet portion, the mixing portion, and the de Laval nozzle portion all have substantially the same maximum cross-sectional area, and each maximum cross-section is defined on a plane perpendicular to the flow direction, i.e., a substantially similar maximum horizontal cross-section forming a circular shape. It should be noted that in the context of similar cross-sections, the term "substantially" means a deviation of up to 20% from the nominal cross-sectional area value. Typically, the maximum cross-section of the mixing portion is slightly larger than the maximum cross-section of the inlet portion due to the additional volume of the injected gas.

[0084] In some embodiments of the nozzle, the maximum cross-section of the mixing portion is up to 20% larger than the maximum cross-section of the inlet portion.

[0085] In some embodiments of the nozzle, the maximum cross-section of the mixing portion is common with the maximum cross-section of the proximal end. That is, the maximum cross-section of the mixing portion is found at the most downstream portion at the boundary with the proximal end.

[0086] Embodiments The following are optional embodiments according to aspects of the present disclosure and combinations thereof. 1. A method for generating work, comprising: heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering the HTL to the inlet of a nozzle at substantially the first pressure; compressing a gas to substantially the first pressure by a compressor and heating the compressed gas to a temperature substantially below the first temperature within a heat-receiving portion of a heat exchanger; mixing, within the nozzle, the HTL at the first pressure and the first temperature with the compressed gas at substantially the first pressure and at a temperature substantially below the first temperature to obtain a mixture of gas and HTL, wherein the gas and HTL in the mixture reach substantially the same temperature after the mixing; Enable the gas in the mixture to undergo isothermal or near-isothermal expansion to a second pressure lower than the first pressure within the nozzle, thereby accelerating the mixture towards the outlet of the nozzle, Discharge the mixture through the outlet to generate mechanical work, Introduce the discharged gas into the heat removal portion of the heat exchanger to exchange heat with the compressed gas exiting the compressor, Direct at least a portion of the discharged HTL towards the heating volume, a method comprising. 2. The method according to embodiment 1, wherein the compressing comprises isothermal compression or near-isothermal compression of the gas. 3. A method for realizing a heat engine, Introduce a heat transfer liquid (HTL) into a nozzle at a first pressure and a first temperature, Isothermally compress a gas by a compressor from a second pressure and a second temperature, wherein the second pressure and temperature are lower than the first pressure and the first temperature respectively, to the first pressure, Heat to approximately the first temperature by passing the compressed gas exiting the isothermal compressor at the first pressure and the second temperature through the heat receiving portion of a countercurrent heat exchanger, Inject the heated gas exiting the heat receiving portion of the heat exchanger into the nozzle to obtain a mixture of HTL and gas, thereby expanding the mixture isothermally or near-isothermally to the second pressure and causing acceleration of the mixture within the nozzle, Discharge the accelerated mixture from the outlet of the nozzle, Recover the gas discharged at approximately the second pressure and approximately the first temperature in the heat removal portion of the heat exchanger for heat exchange with the new compressed gas exiting the compressor, a method comprising. 4. The method according to any one of embodiments 1 to 3, wherein the gas introduced into the heat exchanger subsequent to its discharge from the nozzle is repeatedly isothermally or near-isothermally compressed, thereby forming a closed-loop flow of the gas. 5. The method according to any one of Embodiments 1 to 3, wherein the gas entering the compressor is air under environmental conditions, and the gas exiting the heat exchanger after heat removal is discharged to the surroundings. 6. The method according to any one of Embodiments 1 to 5, wherein the HTL is selected from the list consisting of molten salt, heat transfer oil, ethylene glycol, water, molten metal, or any combination thereof. 7. The method according to any one of Embodiments 1 to 6, wherein the gas is one from the list consisting of air, nitrogen, argon, CO 2 , or any combination thereof. 8. Monitoring the HTL temperature, and controllably discharging the gas from a compressed gas storage unit that stores the stored gas at approximately the first pressure and approximately the second temperature to a portion of the flow path between the compressor and the heat receiving portion, or directly to the heat receiving portion. The controllable discharging is performed based on the HTL temperature to obtain a constant volume flow rate injection into the nozzle. The method according to any one of Embodiments 1 to 7. 9. Monitoring the HTL temperature, and controllably discharging the gas from a compressed gas storage unit that stores the compressed gas at approximately the first pressure and approximately the first temperature to a portion of the flow path between the heat receiving portion and the nozzle, or directly to the nozzle. The controllable discharging is performed based on the HTL temperature to obtain a constant volume flow rate injection into the nozzle. The method according to any one of Embodiments 1 to 8. 10. The stored gas is at approximately the first pressure and approximately the second temperature, The controllable discharging includes discharging the compressed gas to the heat receiving portion. The method according to Embodiment 9. 11. The compressed gas is at approximately the second temperature or approximately the first temperature, and the volume flow rate from the gas storage unit is

[0087]

Number

[0088] [Number] is the volumetric flow rate or the first time derivative of the volume of the gas entering the nozzle, and the temperature is in Kelvin, the method according to any one of Embodiments 8 to 10. 12. The compressed gas is at approximately the first pressure and approximately the first temperature, The controllable discharging includes discharging the stored gas downstream of the heat receiving portion and upstream of the nozzle, or directly discharging it into the nozzle, the method according to Embodiment 9. 13. The method according to any one of Embodiments 1 to 12, including maintaining a constant volumetric flow rate of the gas in the nozzle along the range of the HTL operating temperature. 14. The method according to any one of Embodiments 1 to 13, including maintaining equal static pressure at the inlet of the nozzle, or in the mixing region of the nozzle where the HTL is mixed with the gas, and at the proximal end of the outlet region in the nozzle that is higher than 50% of the stagnation pressure. 15. The method according to any one of Embodiments 1 to 14, wherein the first temperature, the first pressure, the second temperature, the second pressure, and the flow rate are within a range of 30% of their nominal values. 16. The method according to any one of Embodiments 1 to 15, wherein the discharging results in rotation of the nozzle, thereby generating work. 17. The method according to Embodiment 16, wherein the nozzle is part of a reaction turbine. 18. The method according to Embodiment 17, wherein the discharging is performed at a non-zero velocity to form a film flow on the injected surface. 19. The method according to any one of Embodiments 1 to 18, including separating the HTL from the gas following the discharging. 20. The method according to Embodiment 19, wherein the separating includes directing the discharged mixture onto a surface. 21. The method according to any one of Embodiments 1 to 20, comprising recovering a portion of the discharged HTL into a nozzle and passing through another cycle. 22. A system for generating work, a heating volume for enabling a heat transfer liquid (HTL) to be heated to a first temperature by a heat source, a pump for increasing the pressure of the HTL to a first pressure at the first temperature, a compressor configured to compress a gas to approximately the first pressure, a heat exchanger in fluid communication with the compressor and configured to receive the compressed gas at its heat receiving portion and enable heat transfer to the compressed gas to increase the temperature of the compressed gas to approximately below the first temperature, a nozzle in fluid communication with the heat exchanger and the HTL pump, the nozzle having an inlet portion for receiving the HTL and a mixing portion for (i) enabling the HTL at approximately the first temperature and approximately the first pressure to be mixed with the gas at approximately below the first temperature and approximately the first pressure to obtain a mixture, and (ii) enabling the mixture to undergo an isothermal expansion to a second pressure lower than the first pressure, thereby accelerating the mixture in the nozzle towards the outlet of the nozzle, a turbine configured to rotate as a result of the acceleration of the mixture, thereby converting the kinetic energy of the mixture into work, a separation unit for separating the HTL and the gas, the separation unit comprising a collection unit for collecting the discharged HTL and for enabling it to be directed to any one of the heating volume, the pump or the nozzle, or to one of the nozzle and the heating volume or the pump, A system in which the separated and discharged gas is transferred to the heat removal portion of the heat exchanger to exchange heat with the new compressed gas flowing out of the compressor at the heat receiving portion. 23. The system according to Embodiment 22, wherein the cooled gas exiting the heat removal portion of the heat exchanger flows towards the compressor, thereby forming a closed loop flow of the gas. 24. The cooled gas exiting the heat removal portion of the heat exchanger flows to the surroundings, and the compressor is configured to receive the gas from the surroundings and compress the gas to approximately the first pressure, thereby forming an open system, according to the system of Embodiment 22. 25. The system according to any one of Embodiments 22 to 24, wherein the HTL is selected from the group consisting of molten salt, heat transfer oil, molten metal, ethylene glycol, water, or any combination thereof. 26. The gas is air, nitrogen, argon, CO 2 , or is selected from the group consisting of any combination thereof, according to the system of any one of Embodiments 22 to 25. 27. A compressed gas storage unit that stores compressed stored gas at approximately the first pressure and approximately the second temperature and is in fluid communication with the flow path portion between the compressor and the heat receiving portion, wherein the gas storage unit is configured to controllably release the gas based on the sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle, according to the system of any one of Embodiments 22 to 26. 28. A compressed gas storage unit that stores compressed gas at approximately the first pressure and approximately the first temperature and is in fluid communication with the flow path portion between the heat receiving portion and the nozzle, wherein the compressed gas storage unit is configured to controllably release the gas based on the sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle, according to the system of any one of Embodiments 22 to 27. 29. A temperature sensor configured to sense the temperature of the HTL at at least one location along the flow path of the HTL, generate HTL temperature data based thereon, and transmit the HTL temperature data to a controller of the compressed gas storage unit to control a valve for performing the controllable release, according to the system of Embodiment 27 or 28. 30. The system according to Embodiment 29, wherein the temperature sensor is configured to sense the temperature of the HTL at at least one location along the flow path of the HTL between the discharge of the HTL from the nozzle and the introduction of the HTL into the nozzle. 31. The system according to embodiment 29 or 30, wherein the temperature sensor is configured to sense the temperature of the HTL within the collection unit. 32. The compressed gas is at approximately the first pressure and approximately the second temperature, The system according to embodiment 30 or 31, wherein the compressed gas storage unit is in fluid communication with the heat receiving portion. 33. The compressed stored gas is at approximately the second temperature or approximately the first temperature, and the volumetric flow rate from the gas storage unit is

[0089]

Number

[0090]

Number

Brief Description of the Drawings

[0091] To better understand the subject matter disclosed herein and to illustrate how it can be actually implemented, embodiments will now be described by way of non-limiting examples only with reference to the accompanying drawings.

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Mode for Carrying Out the Invention

[0092] The following drawings are provided to illustrate embodiments and implementations of the invention of the present disclosure.

[0093] FIGS. 1A-1B are block diagrams illustrating non-limiting examples of a system for generating work according to one aspect of the present disclosure. Referring first to FIG. 1A. This system provides a heat engine based on an open or closed Ericsson thermodynamic cycle implemented in a two-phase flow. System 100 receives a heat transfer liquid (HTL) from a preheat reservoir 104 and includes a heating volume 102 configured to heat the heat transfer liquid with heat Q in provided by an external heat source. The heat source can be of any type capable of heating the HTL, such as, for example, flue gas, molten salt, heat transfer oil, or waste heat extracted through steam. The HTL is heated to a first temperature within the heating volume 102 and is sent to an input reservoir 106 configured to be in fluid communication with the nozzles of the turbine 108 and introduce the heated HTL into the nozzles at a selected and controlled flow rate. The HTL is optionally pressurized to a first pressure before being introduced into the nozzle or nozzles as part of an impeller within the reaction turbine 108. The increase in the pressure of the HTL occurs either within the preheat reservoir 104 or the input reservoir 106, (as further described below) by the centrifugal force of the reaction turbine, at any other location within the flow path between the discharge of the HTL from the turbine and the reintroduction of the HTL through the input reservoir 106, or at two or more of these locations. This is typically accomplished by a pump (not shown). Thus, the HTL introduced into the nozzles connected to the turbine 108, or some nozzles that are part of the turbine, is at the first temperature and the first pressure.

[0094] The system further includes a compressor 110 configured to receive gas at a second pressure and compress it to the first pressure. The gas compression by the compressor 110 is heat Q exiting the system outIt is accompanied by. Optionally, the compression is isothermal or near-isothermal. The compressed gas having the first pressure and the second temperature is directed to the heat-receiving portion 111 of the countercurrent heat exchanger 112 of the system 100. The gas is heated to approximately the first temperature within the heat exchanger 112. This is accomplished by exchanging heat with the high-temperature gas discharged from the turbine, i.e., the reheater, as will be further described below.

[0095] The gas exiting the heat-receiving portion 111 of the countercurrent heat exchanger 112 is injected into the mixing portion of the nozzles of the turbine 108 and mixed with the HTL to obtain a gas-HTL mixture. Thus, the gas having approximately the first temperature and the first pressure is mixed with the HTL having the first temperature and the first pressure. Note that there may be a difference in temperature or pressure between the gas and the HTL. For example, the gas can be injected into the turbine at a temperature or pressure up to 20% lower than the temperature or pressure of the HTL. In the nozzles, the mixture undergoes an expansion to a second pressure lower than the first pressure. In particular, during the expansion of the gas, heat is transferred from the HTL, which has a heat capacity much larger than that of the gas, to the gas, maintaining the gas at approximately the same temperature, so the expansion is isothermal or near-isothermal. The expansion of the gas results in an acceleration of the mixture towards the exit of the nozzles. The kinetic energy of the accelerated mixture is used to generate work. Typically, the discharged mixture rotates the turbine, making it a reaction turbine, and this rotation results in the generation of work, i.e., the generation of electricity. As described above, the gas and the HTL are discharged from the nozzles at a second pressure lower than the first pressure. The mixture is discharged at approximately the first temperature and directed to the heat-removing portion 113 of the countercurrent heat exchanger 112 to exchange heat with the gas passing through the heat-receiving portion 111 of the countercurrent heat exchanger 112. Thus, the gas exiting the heat-removing portion 113 of the countercurrent heat exchanger 112 is at approximately the second temperature and approximately the second pressure. The gas exiting the heat-removing portion 113 of the countercurrent heat exchanger 112 is directed to the compressor 110 to undergo another cycle within the system. The increase and decrease in the gas temperature in the heat exchanger 112 occur isobarically or near-isobarically.

[0096] In some embodiments of the system, the gas is air, and it should be noted that when the gas exits the heat removal portion 113 of the counterflow heat exchanger 112, the gas is released to the environment and the ambient air is introduced into the compressor 110. Thus, the system can operate in either a closed cycle or an open cycle.

[0097] Only the HTL discharged from the nozzles of the turbine 108, or a portion thereof, is directed to the preheat reservoir 102 to undergo another cycle within the system.

[0098] Referring now to FIG. 1B, this figure shows a system different from FIG. 1A by further comprising a compressed gas storage unit 117 and a separation unit 119. There are two alternative realizations for the compressed gas storage unit 117. In the first alternative realization, the compressed gas storage unit 117 contains compressed gas, such as air, at approximately the first pressure and approximately the second temperature, and is connected to the flow path between the compressor 110 and the counter-flow heat exchanger 112 for discharging the compressed gas to the heated portion of the counter-flow heat exchanger 112. In the second alternative realization, the compressed gas storage unit 117 contains high-temperature compressed gas, such as air at approximately the first temperature and approximately the first pressure, and is connected to the flow path between the counter-flow heat exchanger 112 and the turbine 108 or the nozzle of the turbine 108 for discharging the high-temperature compressed gas downstream of the heated portion of the counter-flow heat exchanger 112. It should be noted that in a typical realization of the system, only one of the two options for the compressed gas storage unit is used. As can be understood, the communication between the compressed gas storage unit 117 and the standard flow path of the system can be two-way communication. This enables the compressed gas storage unit 117 to be filled with compressed gas at either high or low temperature for later use if necessary. This process of filling the compressed gas storage unit 117 is performed prior to the standard operation of the system as a preparatory step. A controller (not shown) of the compressed gas storage unit 117 is configured to control the gas discharge based on the temperature of the HTL sensed in the collection unit 121 or the input reservoir 106 of the separation unit 119. Optionally, the compressed gas storage unit 117 has an input connected from the compressor and an output conduit connected to the heat exchanger. Optionally, a control valve based on the readings of a flow meter and a temperature gauge positioned in the output conduit of the compressed gas storage unit controls the flow rate.

[0099] The separation unit 119 is configured to separate the gas and the HTL from the HTL and gas mixture following discharge from the nozzle. For example, the separation unit 119 may include a curved surface from which the mixture is discharged, and engagement with the surface results in a flow on the surface that experiences a centrifugal force that causes separation between the HTL and the gas. The HTL is collected within a collection unit 121 that defines a drain. A portion of the HTL is sent back to the preheat reservoir 104 and then to the heating volume 102 to be reheated, and a portion of the HTL is sent back to the turbine 108 to undergo another cycle. In an embodiment of the system where the turbine 108 is a reaction turbine, i.e., an embodiment of the system where the nozzle rotates due to the discharge of the mixture therefrom, thereby generating electricity, the operation of the turbine 108 creates a suction condition within the drain of the collection unit 121, thereby sucking the HTL from the drain into the nozzle at approximately a first pressure. Also, the portion of the HTL sent for reheating within the heating volume 102 can be pumped back to the drain at approximately a second pressure and back to the nozzle at approximately the first pressure due to the suction condition induced by the reaction turbine. This is further illustrated below with respect to FIGS. 5A - 5B.

[0100] Optionally, in any one of the embodiments described above, the operating temperature of the nozzle, i.e., the first temperature, is 100 °C or higher, and the operating pressure of the nozzle, i.e., the first pressure, is 10 Bar or higher.

[0101] The Ericsson cycle ideally supports the Carnot efficiency, and the work generated by this system is

[0102]

Number

[0103] The gas in the system can be any of air, nitrogen, argon, CO2, helium, or any other gas suitable for the realization of such a system.

[0104] In some embodiments of the above system, it can be used to provide a constant output power at a constant voltage frequency.

[0105] Isobaric heating in the Ericsson cycle maintains the pressure regardless of the HTL temperature. A lower HTL temperature results in a smaller thermal expansion with heating and a lower volume flow rate of the gas injected into the HTL. By increasing the volume flow rate,

[0106] [Number] can be kept constant. This is achieved by adding a compressed gas tank or compressed gas storage between the compressor and the nozzle (not shown) to store a sufficient amount of extra gas when the HTL is at a low temperature. Optionally, this gas storage is at a compressed low temperature between the compressor and the heat exchanger. Optionally, the storage is between the heat exchanger and the nozzle for the high-temperature gas storage. Controlling the flow rate is done by a valve controlled by a control unit supplied with data on the HTL temperature monitored in the system.

[0107] Refer to FIG. 3, which is a block diagram illustrating an embodiment of a system in which the heat source is in the form of solar radiation.

[0108] Throughout the drawings of the present application, similar elements in different drawings are given similar reference numerals shifted by several hundreds corresponding to the numbers of the respective drawings. For example, element 308 in FIG. 3 performs the same function as element 108 in FIG. 1.

[0109] In this non-limiting example, the heating volume 302 is heated by solar radiation and is either part of or disposed proximate to the turbine 308. Thus, the HTL circulation can be carried out at a very low temperature difference due to minimal head loss. For example, a difference of 10 degrees Celsius or 50 degrees Celsius between the HTL entering the turbine 308 and the HTL exiting the turbine. In some embodiments, the turbine comprises the heating volume and the entire HTL volume is cooled by the turbine while being heated by solar radiation to maintain a constant average temperature. This allows for a sub-degree temperature reduction. Once the solar radiation available as a heat source is depleted, the turbine can operate as previously shown in FIG. 1 using the high-temperature and low-temperature HTL reservoirs.

[0110] Next, refer to FIG. 4, which is a schematic view of a nozzle 320 that can be used in any of the configurations of the system of the present disclosure. The nozzle 320 is formed from three successive parts: an inlet part 322 in fluid communication with a supply of hot and pressurized HTL, a mixing part 324 configured to mix the HTL with an injected gas, and a de Laval part 326 where isentropic expansion occurs. The de Laval part 326 extends between a proximal end 328 that abuts the mixing part 324 and a distal end 330 that typically functions as the outlet of the nozzle. Due to the unique configuration of the system, the inlet part 322 of the nozzle 320 is as wide as desired and can have the same pressure as the start of the outlet part, which has the highest pressure within the nozzle. The inlet part 322 and the mixing part 324 typically have approximately the same cross-sectional area as the proximal end 328 of the outlet, which defines the location where the maximum area and pressure exist. This also causes the pressure within the inlet part 322 and the mixing part 324 to be approximately the same as within the proximal end 328. The small spread of the cross-section of the mixing part 324 is less than 20% of its minimum cross-section and is due to the additional volume of the injected gas. Thus, the maximum horizontal cross-section of the inlet part 322 defined on a first plane P1, and the maximum horizontal cross-section of the proximal end of the mixing part 324 and the de Laval part 326 defined on a second plane P2 are approximately the same area, i.e., a difference of less than 20%.

[0111] Optionally, the de Laval nozzle shape follows the de Laval equation cited in the reference: "Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting Nozzle With a Throat Sowmitra Singh", Tiffany Fourmeau, Jin-Keun Choi, Georges and L. Chahine, DOI: 10.1115 / 1.4026855. Such nozzles were investigated for marine propulsion pressures below 10 bar and temperatures below 100 °C. In contrast to marine propulsion, the heat cycle of the present invention operates at maximum pressure and temperature. Figure 4 is an arbitrary geometry for a de Laval two-phase flow nozzle for pressures above 10 bar and temperatures above 100 °C. This difference is hidden in the mixing speed and the geometry of the nozzle.

[0112] Figures 5A-5B are different views of a schematic diagram of a non-limiting example of the implementation of the system and method of the present disclosure, and the turbine is a reaction turbine. Turbine 508 is a 5-nozzle reaction turbine. Turbine 508 includes a drain 552 that is part of the collection unit 521. Drain 552 contains HTL that is collected after being discharged from the nozzles. The HTL is suctioned from the drain 552 to the impeller 554, and the impeller creates centrifugal force when rotating. The suction conditions that cause the suction of the HTL to the impeller 554 are due to the operation of the turbine, i.e., the discharge of the mixture through the nozzles. A portion of the HTL in the drain 552 passes through a heating outlet 553 that directs the HTL to a heated volume. The HTL may pass through a preheating reservoir before reaching the heated volume. The reheated HTL then circulates back through the high-temperature HTL inlet 555 and (i) enters the drain 552 or (ii) enters the turbine 508 or the impeller 554 directly without being mixed with the HTL in the drain 552. A gas, such as air or any other suitable gas, is optionally supplied through a gas inlet 556 at the center of the shaft 558 and reaches a nozzle 520 positioned at the peripheral diameter of the impeller 554 having a tapered-to-flared Delaval shape. The acceleration of the mixture drives the turbine 508 and drives an electromagnetic power generator on the shaft. The jet of the mixture has a non-zero velocity when exiting the nozzle and impinges on the circular wall 562 of the housing 564 of the turbine 508 to create a film flow on the wall, which separates the mixture. The HTL flows into the drain 552 and circulates back to the impeller 554.

[0113] Unless otherwise indicated, throughout this application, the term "about" should be construed as a deviation of ±20% from the nominal value or nominal standard. For example, if a value is about 10, it should be understood to be in the range of 8 to 12. In another example, if a reference is to a first temperature, it should be understood that the temperature can be a deviation of ±20% from the first temperature, which can be characterized by the temperatures of different materials.

Example

[0114] Although not bound by any theory, the following is an example of a controlled volume calculation for Therminol 66 at 400 °C and nitrogen gas (N2) designed for a 100 kW solar receiver, in accordance with the implementation of the above system.

[0115] Consider the volume of N in the inertial reference system. 2

[0116] Step - 1: Start with the controlled volume N of 3 m reaching the compressor under environmental conditions. 3 2 P 1 V 1 = nRT 1 => n = 120.272 mol. => m = 3.367 Kg of N 2

[0117] According to the ideal gas equation PV = nRT, when the gas pressure is increased to approximately 1 Bar to 40 Bar, the volume is reduced to 0.075 m. If the process is carried out isothermally, the heat removed from the gas to the surroundings is as follows: 3 Q 1 = W 1 = P 1 V 1 ln(V 2 / V 1 ) = 1.107 MJ.

[0118] The entropy reduction is dS = Q 1 / T = 3.69 KJ / K

[0119] Step - 2: Heat N with oil at constant pressure to 673 K. 2

[0120] The heat capacity is

[0121]

Number

[0122] Process - 3: Approximately isothermal expansion while doing work; Q 3 = W 3 = V 3 P 3 ln(V 4 / V 3 ) = 0.168 m 3 * 40 Bar * ln(40) = 2.48 MJ

[0123] The entropy reduction is dS = Q 3 / T = 3.69 KJ / K.

[0124] Process - 4: Cooling of N2 in the heat exchanger Q 4 = Q 2 .

[0125] These processes are explained by the P - V diagram and T - S diagram in Figure 2.

[0126] The ideal efficiency of such a cycle is as follows:

[0127]

Number

[0128] The actual efficiency assuming 90% isothermal compression and expansion efficiency is shown below:

[0129]

Number

[0130] Assuming that the heat loss in the turbine remains in the system for reuse, the actual efficiency is as follows:

[0131]

Number

[0132] This last assumption and calculation reaches a higher efficiency than previous constant - volume heating cycles, where the heat of the outgoing gas is only partially recovered.

[0133] This advantage opens the way to an efficient reaction turbine. Conventionally, due to the non - zero velocity of the HTL exiting the nozzles in a reaction turbine under load, it has been considered less efficient than impulse turbines such as Pelton turbines. However, this loss is converted to heat through friction and is maintained in the turbine for recirculation.

Claims

1. A method for generating work, comprising: heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering the HTL to an inlet of a nozzle at approximately the first pressure; compressing a gas by a compressor to approximately the first pressure and heating the compressed gas to approximately below the first temperature within a heat receiving portion of a heat exchanger; within the nozzle, mixing the HTL at the first pressure and the first temperature with the compressed gas at approximately the first pressure and approximately below the first temperature to obtain a mixture of gas and HTL, wherein the gas and the HTL in the mixture reach approximately the same temperature after the mixing; enabling the gas in the mixture to undergo an isothermal or near-isothermal expansion to a second pressure lower than the first pressure within the nozzle, thereby accelerating the mixture towards an outlet of the nozzle; discharging the mixture through the outlet to generate mechanical work; introducing the discharged gas into a heat removal portion of the heat exchanger to exchange heat with the compressed gas exiting the compressor; directing at least a portion of the discharged HTL towards the heating volume.

2. The method according to claim 1, wherein the compressing comprises isothermal compression or near-isothermal compression of the gas.

3. A method for implementing a heat engine, comprising: introducing a heat transfer liquid (HTL) into a nozzle at a first pressure and a first temperature; isothermally compressing a gas by a compressor from a second pressure and a second temperature, wherein the second pressure and temperature are each lower than the first pressure and the first temperature, to the first pressure; heating the compressed gas exiting the isothermal compressor at the first pressure and the second temperature to approximately the first temperature by passing it through a heat receiving portion of a countercurrent heat exchanger; injecting the heated gas exiting the heat receiving portion of the heat exchanger into the nozzle to obtain a mixture of HTL and gas, thereby causing the mixture to undergo an isothermal or near-isothermal expansion to the second pressure and resulting in acceleration of the mixture within the nozzle; discharging the accelerated mixture from an outlet of the nozzle. A method, including recovering, at a heat removal portion of the heat exchanger, a gas discharged at approximately a second pressure and approximately a first temperature for heat exchange with a new compressed gas exiting the compressor.

4. The method according to any one of claims 1 to 3, wherein the gas introduced into the heat exchanger following its discharge from the nozzle is repeatedly isothermally or quasi-isothermally compressed, thereby forming a closed loop flow of the gas.

5. The method according to any one of claims 1 to 3, wherein the gas entering the compressor is air under ambient conditions and the gas exiting the heat exchanger after heat removal is discharged to the surroundings.

6. The method according to any one of claims 1 to 5, wherein the HTL is selected from the list consisting of molten salt, heat transfer oil, ethylene glycol, water, molten metal, or any combination thereof.

7. wherein the gas is one from a list consisting of air, nitrogen, argon, CO ２ , or any combination thereof, the method according to any one of claims 1 to 6.

8. Monitoring the HTL temperature; Controllably discharging gas from a compressed gas storage unit that stores the stored gas at approximately the first pressure and approximately the second temperature to a portion of the gas flow path between the compressor and the heat receiving portion or directly to the heat receiving portion; The method according to any one of claims 1 to 7, wherein the controllable discharging is performed based on the HTL temperature to obtain a constant volume flow rate injection into the nozzle.

9. Monitoring the HTL temperature; Controllably discharging gas from a compressed gas storage unit that stores compressed gas at approximately the first pressure and approximately the first temperature to a portion of the flow path between the heat receiving portion and the nozzle or directly to the nozzle; The method according to any one of claims 1 to 8, wherein the controllable discharging is performed based on the HTL temperature to obtain a constant volume flow rate injection into the nozzle.

10. The volume flow rate from the gas storage unit 【Number 1】 According to, in the formula, T ＨＴＬ is the temperature of the HTL, 【Number 2】 is the volume flow rate of the gas entering the nozzle or the first time derivative of the volume, and the temperature is in Kelvin units, according to the method of claim 8 or 9.

11. The method according to any one of claims 1 to 10, including maintaining a constant volume flow rate of the gas in the nozzle along a range of HTL operating temperatures.

12. The method according to any one of claims 1 to 11, comprising maintaining an equal static pressure at the inlet of the nozzle, or in the mixing region of the nozzle where the HTL is mixed with the gas, and at the proximal end of the outlet region within the nozzle that is higher than 50% of the stagnation pressure.

13. The method according to any one of claims 1 to 12, wherein said discharging results in rotation of the nozzle, thereby generating work.

14. The method according to claim 13, wherein the nozzle is part of a reaction turbine.

15. The method according to claim 14, wherein said discharging is carried out at a non-zero velocity to form a film flow on the surface being injected.

16. The method according to any one of claims 1 to 15, comprising separating the HTL from the gas following said discharging.

17. The method according to claim 16, wherein said separating comprises directing the discharged mixture onto a curved surface.

18. The method according to any one of claims 1 to 17, comprising recovering a portion of the discharged HTL to the nozzle for another cycle.

19. The method according to any one of claims 1 to 18, wherein the first pressure exceeds about 8 Bar and the first temperature exceeds about 100 °C.

20. The method according to any one of claims 1 to 19, wherein the flow of the mixture within the nozzle is a supersonic flow.

21. A system for generating work, comprising a heating volume for enabling heating of a heat transfer liquid (HTL) to a first temperature by a heat source; a pump for raising the pressure of the HTL to a first pressure at the first temperature; a compressor configured to compress a gas to approximately the first pressure; a heat exchanger in fluid communication with the compressor and configured to receive the compressed gas at its heat-receiving portion and enable heat transfer to the compressed gas to increase the temperature of the compressed gas to approximately below the first temperature. A nozzle in fluid communication with the heat exchanger and the HTL pump, the nozzle having an inlet portion for receiving the HTL, and (i) mixing the HTL at approximately the first temperature and approximately the first pressure with the gas at approximately the first temperature or lower and approximately the first pressure to obtain a mixture, and (ii) enabling the mixture to undergo isothermal expansion to a second pressure lower than the first pressure, thereby accelerating the mixture in the nozzle towards the outlet of the nozzle, a mixing portion for this purpose. A turbine configured to rotate as a result of the acceleration of the mixture, thereby converting the kinetic energy of the mixture into work. A separation unit for separating the HTL and the gas, the separation unit comprising a collection unit for collecting the discharged HTL and for directing it to any one of the heating volume, the pump or the nozzle, or towards one of the nozzle and the heating volume or the pump. A system in which the separated and discharged gas is transmitted to the heat removal portion of the heat exchanger to exchange heat with the new compressed gas flowing out of the compressor in the heat receiving portion. The system according to claim 21, wherein the cooled gas exiting the heat removal portion of the heat exchanger flows towards the compressor, thereby forming a closed loop flow of the gas. The system according to claim 21, wherein the cooled gas exiting the heat removal portion of the heat exchanger flows to the surroundings, and the compressor is configured to receive gas from the surroundings and compress the gas to approximately the first pressure, thereby forming an open system. The system according to any one of claims 21 to 23, wherein the HTL is selected from the group consisting of molten salt, heat transfer oil, molten metal, ethylene glycol, water, or any combination thereof. Comprising a compressed gas storage unit for storing the compressed storage gas at approximately the first pressure and approximately the second temperature, and in fluid communication with the flow path portion between the compressor and the heat receiving portion or directly in fluid communication with the heat receiving portion. ​ ​ ​ The gas is selected from the group consisting of air, nitrogen, argon, CO ２ , or any combination thereof, according to any one of claims 21 to 24. ​ ​ The system according to any one of claims 21 to 25, wherein the gas storage unit is configured to controllably release gas based on the sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.

27. A compressed gas storage unit that stores compressed stored gas at approximately the first pressure and approximately the first temperature and is in fluid communication with a flow path portion between the heat receiving portion and the nozzle or is in direct fluid communication with the nozzle. The system according to any one of claims 21 to 26, wherein the gas storage unit is configured to controllably release gas based on the sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.

28. A temperature sensor configured to sense the temperature of the HTL at at least one location along the flow path of the HTL, generate HTL temperature data based thereon, and transmit the HTL temperature data to a controller of the gas storage unit to control a valve for performing the controllable release. The system according to claim 26 or 27.

29. The system according to claim 28, wherein the temperature sensor is configured to sense the temperature of the HTL at at least one location along the flow path of the HTL between the discharge of the HTL from the nozzle and the introduction of the HTL into the nozzle.

30. The system according to claim 28 or 29, wherein the temperature sensor is configured to sense the temperature of the HTL within the collection unit.

31. The system according to any one of claims 21 to 30, wherein the nozzle is configured to maintain an equal static pressure at the inlet of the nozzle or at a mixing volume where the gas and the HTL are mixed and at the proximal end portion of an outlet region downstream of the mixing volume that is higher than 50% of the stagnation pressure.

32. The system according to any one of claims 21 to 31, wherein the heat source is solar radiation and the heating volume is configured to receive heat from solar radiation and transfer it to the HTL.

33. The system according to any one of claims 21 to 32, wherein the pump is disposed downstream of the nozzle and upstream of the heating volume.

34. The system according to any one of claims 21 to 32, wherein the pump is disposed downstream of the heating volume and upstream of the nozzle.

35. The system according to any one of claims 21 to 34, wherein the nozzle comprises the heating volume.

36. The system according to any one of claims 21 to 35, wherein the nozzle comprises a de Laval nozzle portion defined between a proximal end and a distal end, and the de Laval nozzle portion is defined downstream of the mixing portion.

37. The proximal ends of the inlet portion, the mixing portion, and the de Laval nozzle portion all have approximately the same maximum cross-sectional area, and each maximum cross-section is defined on a plane perpendicular to the flow direction. The maximum cross-section of the mixing portion is at most 20% larger than the maximum cross-section of the inlet portion, and The maximum cross-section of the mixing portion is common with the maximum cross-section of the proximal portion. The system according to claim 36.

38. The system according to any one of claims 21 to 37, wherein the turbine comprises the nozzle, and the nozzle rotates together with the turbine to generate work.

39. The system according to claim 38, wherein the turbine is a reaction turbine.

40. The collection unit defines a drain for accumulating separated HTL, and the HTL is sucked from the drain to the nozzle as a result of the operation of the reaction turbine, and the suction causes the HTL to enter the nozzle at approximately the first pressure. The system according to claim 39.

41. The system according to claim 39 or 40, wherein a part of the reaction turbine forms the pump.

42. The separation unit comprises a curved or circular frame from which the mixture is discharged, and the engagement of the mixture with the curved or circular frame results in a film flow on the surface of the curved or circular frame. The system according to any one of claims 21 to 41.

43. The system according to any one of claims 21 to 42, wherein the first pressure exceeds about 8 Bar and the first temperature exceeds about 100 °C.

44. The system according to any one of claims 21 to 43, wherein the flow of the mixture in the nozzle is a supersonic flow.

45. The system according to any one of claims 21 to 44, for use in the method according to any one of claims 1 to 20.

46. A nozzle for use in a heat engine, comprising: an inlet portion for receiving a heat transfer fluid; a mixing portion for mixing the received HTL with a gas; a de Laval nozzle portion defined between a proximal end and a distal end; wherein the de Laval nozzle portion is defined downstream of the mixing portion, and the mixing portion is defined downstream of the inlet portion; the de Laval portion is configured to allow isothermal expansion of the gas between a first pressure and a second pressure lower than the first pressure. **Claim 47** The nozzle according to claim 46, further comprising an injection port for allowing injection of the gas into the mixing portion. **Claim 48** The proximal ends of the inlet portion, the mixing portion, and the de Laval nozzle portion all have substantially the same maximum cross-sectional area, and each maximum cross-section is defined on a plane perpendicular to the flow direction; the maximum cross-section of the mixing portion is at most 20% larger than the maximum cross-section of the inlet portion; and the maximum cross-section of the mixing portion is common with the maximum cross-section of the proximal end.

Images