WO2023228173A1 - Two-phase heat engine - Google Patents
Two-phase heat engine Download PDFInfo
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- WO2023228173A1 WO2023228173A1 PCT/IL2023/050517 IL2023050517W WO2023228173A1 WO 2023228173 A1 WO2023228173 A1 WO 2023228173A1 IL 2023050517 W IL2023050517 W IL 2023050517W WO 2023228173 A1 WO2023228173 A1 WO 2023228173A1
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- Prior art keywords
- nozzle
- htl
- gas
- temperature
- pressure
- Prior art date
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/06—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids
- F01K25/065—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids with an absorption fluid remaining at least partly in the liquid state, e.g. water for ammonia
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K27/00—Plants for converting heat or fluid energy into mechanical energy, not otherwise provided for
Definitions
- the present disclosure is in the field of heat engines, in particular heat engines that are based on a mixture of two materials, each in a different phase.
- the present disclosure provides a system and a method for producing work.
- the system and the method provide a unique realization of an Ericsson cycle.
- HTL is mixed with gas, both reaching the same temperature following their mixture.
- the HTL and the gas are mixed at about the same pressure and they undergo together as a mixture an expansion in a nozzle from a first pressure to a second pressure, lower than the first pressure. Since the HTL has a much higher heat capacity and the gas is surrounded by the HTL during the expansion, the HTL constantly heats the gas during the expansion, which results in an isothermal or quasi -isothermal expansion in the nozzle.
- reaction turbine achieves high static pressure at minimal head losses.
- 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 experience centrifugal force by the frame.
- reaction turbine avoids cavitation that occurs in impulse turbines.
- the ejected gas is cooled in a heat exchanger, such as a recuperator, and compressed again while it is cold in a compressor.
- a heat exchanger such as a recuperator
- the compression in the compressor is isothermal or quasi-isothermal compression.
- the compressed gas is then heated in the heat exchanger (recuperator) before returning to the turbine.
- the ejected HTL is collected to undergo another cycle in the turbine. A portion of the HTL is reheated by passing through an additional heat exchanger with the heat source.
- a first aspect of the present disclosure provides a method for producing work.
- the method comprises heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering said HTL to an inlet of a nozzle at about a first pressure.
- the method further comprises compressing gas by a compressor to about said first pressure and heating the compressed gas within a heat receiving portion of a heat exchanger to about said first temperature or lower than about said first temperature but higher than about said second temperature, namely a temperature between about said second temperature and about said first temperature.
- the term "about” should be interpreted as a deviation of up to 20%.
- the gas cannot be heated above the first temperature only by receiving heat from the heat exchanger, since the gas that transfer the heat is at said first temperature.
- the method further comprises mixing in said nozzle said HTL at said first pressure and said first temperature with the compressed gas at about said first pressure and about said first temperature or lower than about said first temperature to obtain gas and HTL mixture. It is to be noted that the gas can be mixed with the HTL when it has a temperature that is lower than about said first temperature.
- the gas if is in a temperature lower than about said first temperature, is heated by the HTL to about said first temperature.
- the method further comprises allowing the gas in the mixture to undergo isothermal or quasi -isothermal expansion within said nozzle to a second pressure lower than said first pressure, thereby causing acceleration of said mixture towards an outlet of said nozzle.
- the method further comprises ejecting said mixture through said outlet to produce mechanical work, separating said mixture, and introducing the ejected gas into a heat removal portion of said heat exchanger to exchange heat with compressed gas exits said compressor, and directing the ejected HTL towards said heating volume to undergo another cycle.
- said compressing comprises isothermal or quasi-isothermal compression of said gas.
- Another method aspect of the present disclosure provides a method for realizing a heat engine.
- the method comprising: (i) introducing heat transfer liquid (HTL) into a nozzle at a first pressure and first temperature; (ii) isothermally compressing gas by a compressor from second pressure and second temperature to said first pressure, wherein said second pressure and temperature are lower than said first pressure and first temperature, respectively; (iii) heating the compressed gas, exiting the isothermal compressor at a first pressure and a second temperature, by passing it via a heat receiving portion of a counter flow heat exchanger to about said first temperature or lower than about said first temperature but higher than about said second temperature; (iv) injecting the heated gas exiting the heat receiving portion of said heat exchanger into said nozzle to obtain a HTL and gas mixture, thereby causing the mixture to expand isothermally or quasi-isothermally to said second pressure, resulting in acceleration of the mixture in the nozzle; (v) ejecting the accelerated mixture from an outlet of the nozzle; and (vi
- the gas introduced into the heat exchanger following its ejection from the nozzle is repeatedly isothermally or quasi-isothermally compressed, thereby forming a closed-loop flow of the gas. Namely, after the hot gas that is ejected from the nozzle is passing through the heat exchanger and exchanges its heat with a cooler and compressed gas that exits the compressor, the gas is directed to undergo isothermal or quasi-isothermal compression by the compressor as part of the closed-loop operation.
- said delivering or said introducing the HTL into the nozzle comprises pressurizing said HTL to about said first pressure. After the HTL is ejected from the nozzle, it is at about said second pressure. Therefore, in order to undergo another cycle, it is required to pressurize the HTL to about the first pressure.
- gas entering the compressor is air at ambient conditions and the gas exiting the heat exchanger after heat removal, namely the gas that enters the heat exchanger hot and exits it cooler, is discharged to the surrounding.
- the HTL is selected from a list consisting of: molten salt, thermal oil, ethylene glycol, water, molten metal, or any combination thereof.
- the gas is one from a list consisting of: air, nitrogen, argon, or any combination thereof.
- the method further comprises monitoring the HTL temperature.
- the method further comprises controllably releasing gas from a compressed gas storage storing compressed gas at about said first pressure and at about said second temperature into said heat receiving portion.
- the controllably releasing of the gas is done based on the HTL temperature to obtain a constant output power.
- the method further comprises monitoring the HTL temperature.
- the method further comprises controllably releasing gas from a compressed gas storage storing compressed gas at about said first temperature and at about said first pressure into a location on the flow path of the gas between the heat exchanger and the nozzle or the turbine.
- the compressed gas storage is storing hot compressed gas that is provided in case of a need to a location downstream the heat receiving portion of the heat exchanger.
- the controllably releasing of the gas is done based on the HTL temperature to obtain a constant output power.
- the method further comprises feeding the compressed gas storage with a compressed gas following its compression by the compressor. This is done typically at an initiation process of the method that initially fills the compressed gas storage with a compressed gas, either hot or cold, to be later used if in need, namely due to the changes of the temperature of the HTL.
- a compressed gas either hot or cold
- the HTL temperature is reduced below a desired working temperature, it results in a decrease of the thermal expansion along with the heating, therefore a lower volumetric flow rate enters the nozzle and is mixed with the HTL.
- compensation of additional gas into the cycle is required and is performed by controlling a valve that is controllably opened and closed based on the temperature of the HTL.
- said stored gas is at about said first pressure and about said second temperature.
- the controllable release of the gas from the compressed gas storage is performed downstream the heat receiving portion and upstream or at the nozzle.
- T HTL is the temperature of the HTL
- V gas is the volumetric flow rate of the gas entering the nozzle
- the temperature is in Kelvin units.
- said compressed stored gas is at about said first pressure and about said first temperature.
- the controllable release of the gas from the gas storage is performed into a location of the flow path between the end of the heat receiving portion and the nozzle, including.
- the method further comprises maintaining a constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures, after the gas is heated to the HTL temperature and before the pressure decreases.
- the method further comprises maintaining equal static pressure at an inlet of the nozzle, or at a mixing area of the nozzle where the HTL is mixed with the gas, and at a proximal end portion of an outlet area in the nozzle, which is downstream the mixing area.
- the equal static pressure is higher than 50% of the stagnation pressure.
- said first temperature, first pressure, second temperature, second pressure, and flow rate are within a range of 30% of their nominal value. Namely, there can be deviations of these values to up to 30%.
- said ejecting results in a rotation of the nozzle, thereby producing work.
- said nozzle is part of a reaction turbine, where the nozzle is part of the turbine located at peripheral edges of an impeller where the static and stagnation pressures are the highest.
- said ejecting is performed in a non-zero velocity that forms a film flow over a surface it is injected onto.
- the film flow over the surface results in a separation of the gas and the HTL.
- the method further comprises separating the HTL from the gas following said ejecting.
- said separating comprises directing the ejected mixture onto a curved surface.
- the impact or the 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 a separation of the HTL and the gas.
- the method further comprises retrieving a portion of the ejected HTL into the nozzle to undergo another cycle.
- said retrieving is performed due to the operation of the reaction turbine that results in a suction of the HTL into the nozzle.
- the heat exchanger is a recuperator.
- said first pressure is above about 8, 9, 10, 11 or 12 Bar and the first temperature is above about 100°C.
- the flow of the mixture in the nozzle is a supersonic flow.
- the second pressure is ambient pressure.
- the second temperature is ambient temperature.
- the system comprises a heating volume for allowing heating heat transfer liquid (HTL) to a first temperature by a heat source.
- a pump of the system is configured for raising pressure of said HTL to a first pressure at said first temperature.
- the pump can be positioned in various positions in the system. For example, the pump can be downstream or upstream the heating volume.
- the reaction turbine's inherent centrifugal force is used as a pump for at least part of the HTL. This at least part of the HTL is pumped due to the conditions that the reaction turbine induces and is delivered from the drain (as explained below) to the nozzle while raising its pressure from about the second pressure to about the first pressure.
- the system further comprises a compressor, e.g. an isothermal compressor, configured to compress gas to about said first pressure.
- the system further comprises a heat exchanger in fluid communication with the compressor and is configured to receive the compressed gas into a heat receiving portion thereof to allow transfer of heat to the compressed gas to increase its temperature to about said first temperature or lower than about said first temperature but higher than about said second temperature.
- the system further comprises a nozzle in fluid communication with the heat exchanger and the HTL pump having an inlet portion for receiving said HTL and a mixing portion for (i) allowing mixing said HTL at about said first temperature and at about said first pressure with said gas at about said first temperature and about said first pressure to obtain a mixture and (ii) allowing said mixture to undergo isothermal expansion to a second pressure lower than said first pressure, thereby causing acceleration of said mixture at said nozzle towards an outlet of the nozzle.
- the system further comprises a turbine, e.g. a reaction turbine connected to or part of the nozzle, configured for rotation in result to the acceleration of said mixture, thereby converting the kinetic energy of the mixture to work.
- the system further comprises a separation unit for separating the gas and the HTL.
- the separation unit comprises a collection unit for collecting the ejected HTL and directing it to either the heating volume, the pump, or to the inlet of the nozzle to undergo another cycle without heating it again. Since the volumetric heat capacity of the HTL is about 100-folds higher than that of the gas, the heat transfer from the HTL to the gas during the isothermal expansion in the nozzle only slightly reduces the HTL temperature. Therefore, the HTL can go several cycles in the nozzle before it is required to be heated again. Therefore, the system can be designed that the HTL that accumulates in the collection unit is partially directed to either the heating volume or the pump, depending on their order in the flow path of the system, which can be altered in different realizations of the system, and part of it is directed back to the nozzle to undergo another cycle.
- the ejected gas is directed to a heat removal portion of the heat exchanger to exchange heat with compressed gas in the heat receiving portion that flows from the compressor.
- cooled gas exiting the heat removal portion of the heat exchanger flows towards the compressor, thereby forming a closed-loop flow of the gas.
- cooled gas exiting the heat removal portion of the heat exchanger flows to the surrounding, and the compressor is configured to receive gas from the surrounding to compress it to about said first pressure, thereby forming an open system.
- the gas is selected from the group consisting of: air, nitrogen, argon, or any combination thereof.
- the system further comprises a compressed gas storage storing compressed stored gas at about said first pressure and is in fluid communication with a flow path portion between the compressor and said heat receiving portion.
- the compressed gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain either (i) a constant volumetric flow rate injection into the nozzle or (ii) a constant output power.
- the compressed gas storage is configured to primarily be filled with compressed gas that is compressed by the compressor of the system. Following the compression of the gas by the compressor, it is directed to fill the compressed gas storage, either in its hot or cold state, namely after or before passing through the heat exchanger. Therefore, the initial setting of the system may include filling up this compressed gas storage to allow the efficient operation of the system.
- the HTL temperature when the HTL temperature is reduced below a desired working temperature, it results in a decrease of the thermal expansion along with the heating, therefore a lower volumetric flow rate enters the nozzle and mixed with the HTL.
- a compensation of additional gas into the cycle is required and is performed by controlling a valve that is controllably opened and closed based on the temperature of the HTL.
- the system further comprises a temperature sensor that is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL to generate HTL temperature data based thereon, and transmit said HTL temperature data to a controller of the compressed gas storage to control a valve for carrying out said controllable releasing.
- the temperature sensor is configured to sense the temperature of the HTL in a location along the flow path of the HTL between its ejection from the nozzle and the inlet of the nozzle, namely where the HTL enters the nozzle. Any location between along the above defined flow path is suitable for carrying out the sensing of the temperature of the HTL.
- said temperature sensor is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL between its ejection from the nozzle and its introduction into the nozzle.
- said temperature sensor is configured to sense the temperature of the HTL in the collection unit. Namely, the temperature sensor senses the temperature of the accumulated HTL in the collection unit.
- the temperature sensor is configured to sense the temperature of the HTL at an HTL drain that receives the HTL after its ejection from the nozzle.
- said compressed gas is at about said first pressure and about said second temperature.
- the compressed gas storage is in fluid communication with said heat receiving portion or a portion upstream thereto. Namely, the compressed gas storage is coupled to a portion of the flow path between the compressor and the heat receiving portion of the heat exchanger.
- said compressed gas is at about said first pressure and about said first temperature.
- the compressed gas storage is in fluid communication with said heat removal portion or downstream thereto. Namely, the hot compressed gas from the compressed gas storage is in fluid communication with a portion of the flow path downstream the heat receiving portion of the heat exchanger and upstream the nozzle or at times with the nozzle itself
- the compressed gas storage comprises a controller that is configured for maintaining constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures.
- the nozzle is configured to maintain an equal static pressure at an inlet of the nozzle, or at a mixing volume of the nozzle where the gas and the HTL are mixed, and at the proximal end of the outlet area, which is downstream said mixing volume.
- the static pressure is higher than 50% of the stagnation pressure.
- said first temperature, first pressure, second temperature, second pressure and flow rate are within a range of 30% of their nominal value. Namely, there can be deviations of these values to up to 30%.
- the heat source is solar radiation
- the heating volume is configured for receiving heat from solar radiation and transferring it to the HTL.
- the pump is disposed downstream the nozzle and upstream the heating volume.
- the pump is disposed downstream the heating volume and upstream the nozzle.
- the nozzle comprises said heating volume.
- said nozzle comprises a de Laval nozzle supersonic converging-diverging portion, namely a portion defined by an asymmetric hourglass shape.
- the de Laval nozzle portion is defined between a proximal end and a distal end, and wherein said de Laval nozzle portion is defined downstream said mixing portion.
- the De Laval nozzle cross-section has circular geometry.
- the De Laval nozzle cross-section has rectangular geometry, with round corners.
- the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area.
- Each maximal cross section pf these portion is defined on a plane normal to the flow direction, namely about a similar maximal horizontal cross section that forms a circular shape. It is to be noted the term "about" in the context of similar cross section means a deviation of up to 20% from a nominal cross section area value.
- the maximal cross section of the mixing portion is slightly larger than that of the inlet portion due to the additional volume of the injected gas.
- the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
- the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end. Namely, the maximal cross section of the mixing portion is found at the most downstream portion thereof that borders with the proximal end.
- the turbine comprises said nozzle and the nozzle rotates together with the impeller to produce work. Namely, the ejection of the accelerated mixture through the nozzle causes it to rotate, which results in a generation of work the is used to produce electricity by the rotation.
- the turbine is a reaction turbine.
- the collection unit defines a drain for accumulating the separated HTL.
- a portion of the HTL is suctioned from the drain into the nozzle, resulting in an increase of the HTL pressure from about said second pressure to about said first pressure, due to the operation of the reaction turbine.
- there is a duct linking between the nozzle and the drain and the ejection of the mixture through the nozzle generates suction conditions that result in an increase of pressure of the HTL to about the first pressure and its delivery into the nozzle or an inlet of the nozzle.
- the separation unit comprises a curved or circular frame onto which the mixture is ejected.
- the engagement of the mixture with the curved or circular frame results in a film flow on a surface of the curved or circular frame.
- the flow on the surface experiences centrifugal force applied by the frame, which results in a separation of the HTL and the gas.
- the heat exchanger is a recuperator.
- a part of the reaction turbine forms said pump.
- the pump is disposed or defined between the drain and the nozzle. Namely, the pump is defined downstream the drain and upstream the nozzle.
- said first pressure is above about 8, 9, 10, 11 or 12 Bar and the first temperature is above about 100°C.
- the second pressure is ambient pressure.
- the second temperature is ambient temperature.
- the flow of the mixture in the nozzle is a supersonic flow.
- a nozzle for use in a heat engine.
- the nozzle comprising an inlet portion for receiving a heat transfer fluid; a mixing portion for mixing the received HTL with gas; and a de Laval nozzle portion, namely 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 said mixing portion and said mixing portion is defined downstream said inlet portion.
- the de Laval portion is configured to allow an isothermal expansion of the gas between a first pressure to a second pressure lower than the first pressure.
- the nozzle further comprises an injection port for allowing an injection of gas to the mixing portion.
- the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction, namely about a similar maximal horizontal cross section that forms a circular shape.
- each maximal cross section is defined on a plane normal to the flow direction, namely about a similar maximal horizontal cross section that forms a circular shape.
- the term "about" in the context of similar cross section means a deviation of up to 20% from a nominal cross section area value.
- the maximal cross section of the mixing portion is slightly larger than that of the inlet portion due to the additional volume of the injected gas.
- the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
- the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end. Namely, the maximal cross section of the mixing portion is found at the most downstream portion thereof the borders with the proximal end.
- a method for producing work comprising: heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering said HTL to an inlet of a nozzle at about a first pressure; compressing gas by a compressor to about said first pressure and heating the compressed gas within a heat receiving portion of a heat exchanger to about said first temperature or lower than about said first temperature; mixing in said nozzle said HTL at said first pressure and said first temperature with the compressed gas at about said first pressure and about said first temperature or lower than about said first temperature to obtain a gas and HTL mixture, wherein the gas and the HTL in the mixture reaches to about the same temperature after said mixing; allowing the gas in the mixture to undergo isothermal or quasi -isothermal expansion within said nozzle to a second pressure lower than said first pressure, thereby causing acceleration of said mixture towards an outlet of said nozzle; ejecting said mixture through said outlet to produce mechanical work; introducing the ejected gas into a heat removal portion of said heat exchanger to exchange heat with compressed gas exits
- a method for realizing a heat engine comprises: introducing heat transfer liquid (HTL) into a nozzle at a first pressure and first temperature; isothermally compressing gas by a compressor from second pressure and second temperature to said first pressure, wherein said second pressure and temperature are lower than said first pressure and first temperature, respectively; heating the compressed gas, exiting the isothermal compressor at a first pressure and a second temperature, by passing it via a heat receiving portion of a counter flow heat exchanger to about said first temperature; injecting the heated gas exiting the heat receiving portion of said heat exchanger into said nozzle to obtain a HTL and gas mixture, thereby causing the mixture to expand isothermally or quasi-isothermally to said second pressure, resulting in acceleration of the mixture in the nozzle; and ejecting the accelerated mixture from an outlet of the nozzle; retrieving the ejected gas at about a second pressure and about a first temperature to a heat removal portion of the heat exchanger for exchanging heat to new compressed gas exiting from the compressor.
- HTL heat
- a system for producing work comprising: a heating volume for allowing heating heat transfer liquid (HTL) to a first temperature by a heat source; a pump for raising pressure of said HTL to a first pressure at said first temperature; a compressor configured to compress gas to about said first pressure; a heat exchanger in fluid communication with the compressor and configured to receive the compressed gas into a heat receiving portion thereof to allow transfer of heat to the compressed gas to increase its temperature to about said first temperature or lower than about said first temperature; a nozzle in fluid communication with the heat exchanger and the HTL pump having an inlet portion for receiving said HTL and a mixing portion for (i) allowing mixing said HTL at about said first temperature and at about said first pressure with said gas at about said first temperature or lower than about said first temperature and about said first pressure to obtain a mixture and (ii) allowing said mixture to undergo isothermal expansion to a second pressure lower than said first pressure, thereby causing acceleration of said mixture at said nozzle towards an outlet of the nozzle; a turbine configured for rotation in result to the
- HTL is selected from the group consisting of: molten salt, thermal oil, molten metal, ethylene glycol, water, or any combination thereof.
- any one of embodiments 22-27 comprising a compressed gas storage storing compressed gas at about said first pressure and at about said first temperature and is in fluid communication with a flow path portion between the heat receiving portion and the nozzle; wherein the compressed gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.
- the system of embodiment 27 or 28, comprising a temperature sensor that is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL to generate HTL temperature data based thereon, and transmit said HTL temperature data to a controller of the compressed gas storage to control a valve for carrying out said controllable releasing.
- nozzle is configured to maintain an equal static pressure at an inlet of the nozzle or at a mixing volume where the gas and the HTL are mixed, and at a proximal end portion of an outlet area that is downstream the mixing volume that is higher than 50% of the stagnation pressure.
- said nozzle comprises a de Laval nozzle portion defined between a proximal end and a distal end, wherein said de Laval nozzle portion is defined downstream said mixing portion.
- 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 gas; and a de Laval nozzle portion defined between a proximal end and a distal end; wherein said de Laval nozzle portion is defined downstream said mixing portion and said mixing portion is defined downstream said inlet portion; and wherein said de Laval portion is configured to allow an isothermal expansion of the gas between a first pressure to a second pressure lower than the first pressure.
- the nozzle of embodiment 51 comprising an injection port for allowing an injection of gas to the mixing portion.
- Figs. 1A-1B are block diagrams showing different non-limiting examples of embodiments of a system according to an aspect of the present disclosure.
- Fig- 2 shows P-V and T-S diagrams for thermal oil and N2 mixture at 400C.
- Figs. 3 is a block diagram showing a non-limiting example of an embodiment of a system according to an aspect of the present disclosure.
- Figs 5A-5B are schematic illustrations of different views of a non-limiting example of a realization of part of the system, wherein the turbine is a reaction turbine.
- Fig. 5A is a top view;
- Fig. 5B is a cross-sectional view.
- Figs. 1A-1B are block diagrams exemplifying non-limiting examples of a system for producing work according to an aspect of the present disclosure.
- the system provides a heat engine that is based on an open or closed Ericsson thermodynamic cycle realized on two-phase flow.
- the system 100 comprises a heating volume 102 that is configured to receive a heat transfer liquid (HTL) from a preheat reservoir 104 and to heat it with heat Qin that is provided by an external heat source.
- HTL heat transfer liquid
- the heat source can be of any type that can heat the HTL, such as waste heat, that is extracted through, for example, flue gas, molten salt, thermal oil or steam.
- the HTL is heated in the heating volume 102 to a first temperature and is delivered to an input reservoir 106 that is in fluid communication with a nozzle of a turbine 108 and is configured to introduce the heated HTL into the nozzle at a selected and controlled flow rate.
- the HTL is pressurized to a first pressure prior to the introduction to the nozzle or nozzles, optionally as part of the impeller in a reaction turbine 108.
- the system further comprises a compressor 110 that is configured to receive gas at a second pressure and compress it to the first pressure.
- the gas compression by the compressor 110 involves heat Q ou t exiting the system.
- the compression is isothermal or quasi-isothermal.
- the compressed gas having a first pressure and a second temperature is directed to a heat receiving portion 111 of a counter-flow heat exchanger 112 of the system 100.
- the gas is heated in the heat exchanger 112 up to about the first temperature. This is performed by exchanging heat with hot gas that is ejected from the turbine, namely a recuperator, as further explained below.
- the gas undergoes an expansion that is isothermal or quasiisothermal as during the expansion, the heat from the HTL, which has a heat capacity much larger than that of the gas, is transferred to the gas and maintain it at about the same temperature.
- the expansion of the gas results in acceleration of the mixture towards the outlet of the nozzle.
- the kinetic energy of the accelerated mixture is used for producing work.
- the ejected mixture causes the turbine to rotate, making it a reaction turbine, and this rotation results in production of work, i.e. generation of electricity.
- the gas and the HTL are ejected from the nozzle at a second pressure, that is lower than the first pressure.
- the gas is air and upon its exit from the heat removal portion 113 of the counter-flow heat exchanger 112 it is released to the environment and ambient air is introduced to the compressor 110. Therefore, the system can operate in either a closed or open cycle.
- the HTL that is ejected from the nozzle of the turbine 108, or only a portion thereof, is directed to the preheat reservoir 102 to undergo another cycle in the system.
- Fig. IB shows a system that differs from Fig. 1A by further comprising a compressed gas storage 117 and a separation unit 119.
- the compressed gas storage 117 comprises compressed gas, e.g. air, at about first pressure and at about second temperature, and is linked to the flow path between the compressor 110 and the counter flow heat exchanger 112 so as to release compressed gas into the heat receiving portion of the counter flow heat exchanger 112.
- the compressed gas storage 117 comprises hot compressed gas, e.g.
- the communication of the compressed gas storage 117 with the standard flow path of the system can be a two-directional communication. This allows to fill the compressed gas storage 117 with the compressed gas, either hot or cold, for later use if needed. This step of filling up the compressed gas storage 117 cab take place prior to the standard operation of the system as a preliminary step.
- a controller (not shown) of the compressed gas storage 117 is configured to control the release of the gas based on the temperature of the HTL that is sensed in a collection unit 121 of the separation unit 119 or in the input reservoir 106.
- the compressed gas storage 117 has an input connected from the compressor and an output conduit connected to the heat exchanger.
- the separation unit 119 is configured to separate the gas and the HTL from the HTL and gas mixture following its ejection from the nozzle.
- the separation unit 119 may include a curved surface onto which the mixture is ejected and the engagement with the surface results in a flow on the surface the experiences centrifugal force that causes a separation between the HTL and the gas.
- the HTL is collected in a collection unit 121 that defines a drain. A portion of the HTL is delivered back to the preheat reservoir 104 and then to the heating volume 102 to reheat, and part of the HTL is delivered back to the turbine 108 to undergo another cycle.
- the operation of the turbine 108 causes suction conditions in the drain of the collection unit 121, thereby suctioning HTL from the drain into the nozzle in about first pressure.
- the portion of the HTL that is delivered to reheat in the heating volume 102 may return to the drain at about the second pressure and pumped back to the nozzle at about the first pressure due to the suction conditions induced by the reaction turbine.
- the working temperature of the nozzle namely the first temperature is 100°C and above; and the working pressure of the nozzle, namely the first pressure is lOBar and above.
- the thermodynamic cycle T-S and P-V diagrams are depicted in Fig. 2.Quasi-isotherml process allows the HTL to cool for a few degrees along with the expansion, while supporting high output power.
- the HTL can be any liquid carrying heat such as molten metals, molten salt, thermal oil, water, and also liquid with soluble materials such as water with NaCl or ZnCL or NaOH or other soluble materials that are known to raise the boiling point, for example allowing to drive a heat engine on water liquid phase at a temperature higher than 100C.
- the gas in the system can be either air, nitrogen, argon, CO2, Helium, or any other gas that is suitable for the realization of such a system.
- it can be used to provide a constant output power at a constant voltage frequency.
- the isobaric heating in the Ericsson cycle maintains the pressure regardless of the HTL temperature.
- Lower HTL temperature results in a smaller thermal expansion along with the heating and a lower volumetric flow rate of gas injected into the HTL.
- P gas * l ⁇ as const.
- 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 low temperature.
- this gas storage is at the compressing low temperature between the compressor and the heat exchanger.
- the storage is between the heat exchanger and the nozzle , for hot gas storage. Controlling the flow rate is done by a valve that is controlled by a control unit that is fed with data of the HTL temperature that is monitored in the system.
- Fig. 3 is a block diagram exemplifying an embodiments of the system, in which the heat source is in the form of solar radiation.
- element 308 in Fig. 3 serves the same function as element 108 in Fig. 1.
- the heating volume 302 is heated by a solar radiation and is part of the turbine 308 or disposed at a proximity to the turbine. Therefore, the HTL circulation can be done at a very low temperature difference due to the minimal head losses. For example, 10 deg, or 50 deg Celsius difference between the HTL entering and exiting the turbine 308.
- the turbine comprises the heating volume and the entire HTL capacity is both being cooled by the turbine and heated by solar radiation simultaneously, maintaining a constant average temperature. This allows subdegree temperature reduction. Once there is no available solar radiation as a heat source, the turbine can operate as previously shown in Fig. 1 with hot and cold HTL reservoirs.
- Fig. 4 is a schematic illustration 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 of three consecutive portions - an inlet portion 322 that is in fluid communication with a feed of hot and pressurized HTL, a mixing portion 324 that is configured for mixing the HTL with gas injected thereto, and a de Laval portion 326, in which the isothermal expansion occurs.
- the de Laval portion 326 is extending between a proximal end 328 that borders with the mixing portion 324 and a distal end 330 that typically serves as the outlet of the nozzle.
- the inlet portion 322 of the nozzle 320 is allowed to be as broad as desired and at the same pressure as the beginning of the outlet section which has the highest pressure in the nozzle.
- the inlet portion 322 and the mixing portion 324 have about the same cross section area as a proximal end 328 of the outlet, which typically defines where the maximal area and pressure exist. This also causes that the pressure in the inlet portion 322 and the mixing portion 324 is about the same pressure as in the proximal end 328.
- the small broadening of cross section of the mixing portion 324 is less than 20% of minimal cross section thereof and is due to the additional volume of the injected gas.
- the maximal horizontal cross section of the inlet portion 322 defined on a first plane Pl and the maximal horizontal cross section of the mixing portion 324 and the proximal end of the de Laval portion 326 defined on a second plane P2 are about the same area, namely less than 20% difference.
- the De Laval nozzle shape is according to the De-Laval equations as cited in 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 a nozzle was explored for marine propulsion pressure lower than lObar and temperatures lower than 100C.
- heat cycles of the present invention operate at maximal pressure and temperature.
- Fig. 4 is an optional geometry for De Laval two phase flow nozzle for pressure above lOBar and temperature above 100°C. The difference is hidden at the mixture velocities, and the geometry of the nozzle.
- Figs. 5A-5B are different views of schematic illustrations of a non-limiting example of a realization of the system and the method of the present disclosure, wherein the turbine is a reaction turbine.
- the turbine 508 is a 5 nozzles reaction turbine.
- the turbine 508 comprises a drain 552 that is a part of the collection unit 521.
- the drain 552 comprises HTL that is collected after ejected from the nozzles. HTL is sucked from the drain 552 into an impeller 554, which creates centrifugal force when rotating.
- the suction conditions that cause the suction of the HTL into the impeller 554 are due to the operation of the turbine, namely the ejection of the mixture through the nozzle.
- a portion of the HTL in the drain 552 goes through a heating outlet 553 that directs the HTL to a heating volume in which it is heated.
- the HTL may pass through a preheating reservoir prior to reaching the heating volume.
- the reheated HTL is then circulates back through a hot HTL inlet 555 either (i) into the drain 552 or (ii) directly enters the turbine 508 or the impeller 554 without being mixed with the HTL in the drain 552.
- Gas, such as air or any other suitable gas is supplied optionally through a gas inlet 556 at the center of a shaft 558, and reaching the nozzles 520, located at the peripheral diameter of the impeller 554 having converging-diverging De Laval shape.
- the acceleration of the mixture drives the turbine 508 and causing the shaft to drive the electromagnetic power generator.
- the jet of the mixture has a non-zero velocity when exiting the nozzle and is impinging on the circular wall 562 of the housing 564 of the turbine 508 creating a film flow on the walls, which separates the mixture.
- the HTL flows into the drain 552 to be circulated back into the impeller 554.
- the term "about” throughout the application should be interpreted as a deviation of ⁇ 20% of the nominal value or from a nominal reference. For example, if the value is about 10, thus it should be understood to be in the range of 8- 12. In another example, if the reference is to a first temperature than it should be understood that the temperature can be in a deviation of ⁇ 20% from said first temperature that may be characterized by a temperature of a different material.
- Step-1 Starting with a 3m 3 of controlled volume N2 in reaching the compressor at ambient conditions.
- Step-3 Approximately isothermal expansion, while generating work
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Abstract
The present disclosure provides a system and a method for producing work. The system and the method provide a unique realization of an Ericsson cycle. In the solution of the present disclosure, HTL is mixed with gas, both reaching about the same 5 temperature following their mixture. The HTL and the gas are mixed at about the same pressure and undergo together as a mixture an expansion in a nozzle from a first pressure to a second pressure, lower than the first pressure. Since the HTL has a much higher heat capacity and the gas is surrounded by the HTL during the expansion, the HTL constantly heats the gas during the expansion, which results in an isothermal or quasi -isothermal 10 expansion in the nozzle. The expansion of the gas results in an acceleration of the mixture within the nozzle and kinetic energy of the accelerated mixture is converted into work, either by employing the nozzle in a reaction turbine or by using the ejected mixture to drive a turbine, e.g. an impulse turbine. When realizing the present invention in a reaction turbine, the non-zero velocity of the HTL/gas mixture at the outlet of the nozzle is used 15 to separate the mixture by forming a film flow on a circular frame and the film flow experience centrifugal force by the frame. The ejected gas is cooled in a heat exchanger, such as a recuperator, and compressed again while it is cold in a compressor. The compressed gas is then heated in the heat exchanger (recuperator) before returning to the turbine. The ejected HTL is collected to undergo another cycle in the turbine. A portion 20 of the HTL is reheated by passing through an additional heat exchanger with the heat source.
Description
TWO-PHASE HEAT ENGINE
TECHNOLOGICAL FIELD
The present disclosure is in the field of heat engines, in particular heat engines that are based on a mixture of two materials, each in a different phase.
BACKGROUND ART
References considered to be relevant as background to the presently disclosed subject matter are listed below:
- WO 2022/049573
Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.
GENERAL DESCRIPTION
The present disclosure provides a system and a method for producing work. The system and the method provide a unique realization of an Ericsson cycle. In the solution of the present disclosure, HTL is mixed with gas, both reaching the same temperature following their mixture. The HTL and the gas are mixed at about the same pressure and they undergo together as a mixture an expansion in a nozzle from a first pressure to a second pressure, lower than the first pressure. Since the HTL has a much higher heat capacity and the gas is surrounded by the HTL during the expansion, the HTL constantly heats the gas during the expansion, which results in an isothermal or quasi -isothermal expansion in the nozzle. The expansion of the gas results in an acceleration of the mixture within the nozzle and kinetic energy of the accelerated mixture is converted into work, either by employing the nozzle in a reaction turbine or by using the ejected mixture to drive a turbine, e.g. an impulse turbine. Due to efficiency, the solution of the present invention is more suitable to be employed in a reaction turbine. Reaction turbine achieves high static pressure at minimal head losses. 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 experience centrifugal force
by the frame. Finally, reaction turbine avoids cavitation that occurs in impulse turbines. The ejected gas is cooled in a heat exchanger, such as a recuperator, and compressed again while it is cold in a compressor. Optionally, the compression in the compressor is isothermal or quasi-isothermal compression. The compressed gas is then heated in the heat exchanger (recuperator) before returning to the turbine. The ejected HTL is collected to undergo another cycle in the turbine. A portion of the HTL is reheated by passing through an additional heat exchanger with the heat source.
Therefore, a first aspect of the present disclosure provides a method for producing work. The method comprises heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering said HTL to an inlet of a nozzle at about a first pressure. The method further comprises compressing gas by a compressor to about said first pressure and heating the compressed gas within a heat receiving portion of a heat exchanger to about said first temperature or lower than about said first temperature but higher than about said second temperature, namely a temperature between about said second temperature and about said first temperature. The term "about" should be interpreted as a deviation of up to 20%. For example, if a first material is compressed to about a pressure of a second material it is to be interpreted that the first material is within a deviation of 20% from the nominal pressure value of the second material. The same also applies to temperatures. It is to be noted that in the context of the realization of the method or the system of the present disclosure, the gas cannot be heated above the first temperature only by receiving heat from the heat exchanger, since the gas that transfer the heat is at said first temperature. The method further comprises mixing in said nozzle said HTL at said first pressure and said first temperature with the compressed gas at about said first pressure and about said first temperature or lower than about said first temperature to obtain gas and HTL mixture. It is to be noted that the gas can be mixed with the HTL when it has a temperature that is lower than about said first temperature. Therefore, following said mixing, the gas, if is in a temperature lower than about said first temperature, is heated by the HTL to about said first temperature. The method further comprises allowing the gas in the mixture to undergo isothermal or quasi -isothermal expansion within said nozzle to a second pressure lower than said first pressure, thereby causing acceleration of said mixture towards an outlet of said nozzle. The method further comprises ejecting said mixture through said outlet to produce mechanical work, separating said mixture, and introducing the ejected gas into a heat removal portion of
said heat exchanger to exchange heat with compressed gas exits said compressor, and directing the ejected HTL towards said heating volume to undergo another cycle.
In some embodiments of the method, said compressing comprises isothermal or quasi-isothermal compression of said gas.
Another method aspect of the present disclosure provides a method for realizing a heat engine. The method comprising: (i) introducing heat transfer liquid (HTL) into a nozzle at a first pressure and first temperature; (ii) isothermally compressing gas by a compressor from second pressure and second temperature to said first pressure, wherein said second pressure and temperature are lower than said first pressure and first temperature, respectively; (iii) heating the compressed gas, exiting the isothermal compressor at a first pressure and a second temperature, by passing it via a heat receiving portion of a counter flow heat exchanger to about said first temperature or lower than about said first temperature but higher than about said second temperature; (iv) injecting the heated gas exiting the heat receiving portion of said heat exchanger into said nozzle to obtain a HTL and gas mixture, thereby causing the mixture to expand isothermally or quasi-isothermally to said second pressure, resulting in acceleration of the mixture in the nozzle; (v) ejecting the accelerated mixture from an outlet of the nozzle; and (vi) retrieving the ejected gas at about a second pressure and about a first temperature to a heat removal portion of the heat exchanger for exchanging heat to compressed gas exiting from the compressor.
In some embodiments of the method, the gas introduced into the heat exchanger following its ejection from the nozzle is repeatedly isothermally or quasi-isothermally compressed, thereby forming a closed-loop flow of the gas. Namely, after the hot gas that is ejected from the nozzle is passing through the heat exchanger and exchanges its heat with a cooler and compressed gas that exits the compressor, the gas is directed to undergo isothermal or quasi-isothermal compression by the compressor as part of the closed-loop operation.
It is to be noted that any combination of the described embodiments with respect to any aspect of this 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 below embodiments of the method applies to any of the above method aspects.
In some embodiments of the method, said delivering or said introducing the HTL into the nozzle comprises pressurizing said HTL to about said first pressure. After the HTL is ejected from the nozzle, it is at about said second pressure. Therefore, in order to undergo another cycle, it is required to pressurize the HTL to about the first pressure. This can be done by a pumping unit or, in case the method is realized in a reaction turbine, the centrifugal forces of the turbine form suction conditions and practically form a pump that raises the pressure of the HTL to about the first pressure. In some embodiments of the method, gas entering the compressor is air at ambient conditions and the gas exiting the heat exchanger after heat removal, namely the gas that enters the heat exchanger hot and exits it cooler, is discharged to the surrounding.
In some embodiments of the method, the HTL is selected from a list consisting of: molten salt, thermal oil, ethylene glycol, water, molten metal, or any combination thereof.
In some embodiments of the method, the gas is one from a list consisting of: air, nitrogen, argon, or any combination thereof.
In some embodiments, the method further comprises monitoring the HTL temperature. The method further comprises controllably releasing gas from a compressed gas storage storing compressed gas at about said first pressure and at about said second temperature into said heat receiving portion. The controllably releasing of the gas is done based on the HTL temperature to obtain a constant output power.
In some embodiments, the method further comprises monitoring the HTL temperature. The method further comprises controllably releasing gas from a compressed gas storage storing compressed gas at about said first temperature and at about said first pressure into a location on the flow path of the gas between the heat exchanger and the nozzle or the turbine. Namely, the compressed gas storage is storing hot compressed gas that is provided in case of a need to a location downstream the heat receiving portion of the heat exchanger. The controllably releasing of the gas is done based on the HTL temperature to obtain a constant output power.
In some embodiments, the method further comprises feeding the compressed gas storage with a compressed gas following its compression by the compressor. This is done typically at an initiation process of the method that initially fills the compressed gas storage with a compressed gas, either hot or cold, to be later used if in need, namely due to the changes of the temperature of the HTL.
In particular, when the HTL temperature is reduced below a desired working temperature, it results in a decrease of the thermal expansion along with the heating, therefore a lower volumetric flow rate enters the nozzle and is mixed with the HTL. To maintain a constant output power, compensation of additional gas into the cycle is required and is performed by controlling a valve that is controllably opened and closed based on the temperature of the HTL.
In some embodiments of the method, said stored gas is at about said first pressure and about said second temperature. The controllable release of the gas from the compressed gas storage is performed downstream the heat receiving portion and upstream or at the nozzle.
In some embodiments of the method, said compressed stored gas is at about said second temperature, wherein the volume flow rate from the compressed gas storage is according to: THTL * Vgas = const, and wherein THTL is the temperature of the HTL, Vgas is the volumetric flow rate of the gas entering the nozzle, and the temperature is in Kelvin units. In such a control, the isobaric heating of the gas results in constant volume and pressure.
In some embodiments of the method, said compressed stored gas is at about said first pressure and about said first temperature. The controllable release of the gas from the gas storage is performed into a location of the flow path between the end of the heat receiving portion and the nozzle, including.
In some embodiments, the method further comprises maintaining a constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures, after the gas is heated to the HTL temperature and before the pressure decreases.
In some embodiments, the method further comprises maintaining equal static pressure at an inlet of the nozzle, or at a mixing area of the nozzle where the HTL is mixed with the gas, and at a proximal end portion of an outlet area in the nozzle, which is downstream the mixing area. In some embodiments, the equal static pressure is higher than 50% of the stagnation pressure.
In some embodiments of the method, said first temperature, first pressure, second temperature, second pressure, and flow rate are within a range of 30% of their nominal value. Namely, there can be deviations of these values to up to 30%.
In some embodiments of the method, said ejecting results in a rotation of the nozzle, thereby producing work.
In some embodiments of the method, said nozzle is part of a reaction turbine, where the nozzle is part of the turbine located at peripheral edges of an impeller where the static and stagnation pressures are the highest.
In some embodiments of the method, said ejecting is performed in a non-zero velocity that forms a film flow over a surface it is injected onto. The film flow over the surface results in a separation of the gas and the HTL.
In some embodiments, the method further comprises separating the HTL from the gas following said ejecting.
In some embodiments of the method, said separating comprises directing the ejected mixture onto a curved surface. The impact or the 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 a separation of the HTL and the gas.
In some embodiments, the method further comprises retrieving a portion of the ejected HTL into the nozzle to undergo another cycle.
In some embodiments of the method, wherein the turbine is a reaction turbine, said retrieving is performed due to the operation of the reaction turbine that results in a suction of the HTL into the nozzle.
In some embodiments of the method, the heat exchanger is a recuperator.
In some embodiments of the method, said first pressure is above about 8, 9, 10, 11 or 12 Bar and the first temperature is above about 100°C.
In some embodiments of the method, the flow of the mixture in the nozzle is a supersonic flow.
In some embodiments of the method, the second pressure is ambient pressure.
In some embodiments of the method, the second temperature is ambient temperature.
Yet another aspect of the present disclosure provides a system for producing work. The system comprises a heating volume for allowing heating heat transfer liquid (HTL) to a first temperature by a heat source. A pump of the system is configured for raising pressure of said HTL to a first pressure at said first temperature. The pump can be positioned in various positions in the system. For example, the pump can be downstream or upstream the heating volume. Optionally, the reaction turbine's inherent centrifugal force is used as a pump for at least part of the HTL. This at least part of the HTL is pumped due to the conditions that the reaction turbine induces and is delivered from the
drain (as explained below) to the nozzle while raising its pressure from about the second pressure to about the first pressure. In case that the pump formed by the reaction turbine is the only pump in the system, an initiation step of the system is required with external involvement, such as a driver that causes initial operation of the system, e.g. a pump that causes the first cycle of the system. The system further comprises a compressor, e.g. an isothermal compressor, configured to compress gas to about said first pressure. The system further comprises a heat exchanger in fluid communication with the compressor and is configured to receive the compressed gas into a heat receiving portion thereof to allow transfer of heat to the compressed gas to increase its temperature to about said first temperature or lower than about said first temperature but higher than about said second temperature. The system further comprises a nozzle in fluid communication with the heat exchanger and the HTL pump having an inlet portion for receiving said HTL and a mixing portion for (i) allowing mixing said HTL at about said first temperature and at about said first pressure with said gas at about said first temperature and about said first pressure to obtain a mixture and (ii) allowing said mixture to undergo isothermal expansion to a second pressure lower than said first pressure, thereby causing acceleration of said mixture at said nozzle towards an outlet of the nozzle. The system further comprises a turbine, e.g. a reaction turbine connected to or part of the nozzle, configured for rotation in result to the acceleration of said mixture, thereby converting the kinetic energy of the mixture to work. The system further comprises a separation unit for separating the gas and the HTL. The separation unit comprises a collection unit for collecting the ejected HTL and directing it to either the heating volume, the pump, or to the inlet of the nozzle to undergo another cycle without heating it again. Since the volumetric heat capacity of the HTL is about 100-folds higher than that of the gas, the heat transfer from the HTL to the gas during the isothermal expansion in the nozzle only slightly reduces the HTL temperature. Therefore, the HTL can go several cycles in the nozzle before it is required to be heated again. Therefore, the system can be designed that the HTL that accumulates in the collection unit is partially directed to either the heating volume or the pump, depending on their order in the flow path of the system, which can be altered in different realizations of the system, and part of it is directed back to the nozzle to undergo another cycle. The ejected gas is directed to a heat removal portion of the heat exchanger to exchange heat with compressed gas in the heat receiving portion that flows from the compressor.
In some embodiments of the system, cooled gas exiting the heat removal portion of the heat exchanger flows towards the compressor, thereby forming a closed-loop flow of the gas.
In some embodiments of the system, cooled gas exiting the heat removal portion of the heat exchanger flows to the surrounding, and the compressor is configured to receive gas from the surrounding to compress it to about said first pressure, thereby forming an open system.
In some embodiments of the system, the HTL is selected from the group consisting of: molten salt, thermal oil, molten metal, ethylene glycol, water, or any combination thereof.
In some embodiments of the system, the gas is selected from the group consisting of: air, nitrogen, argon, or any combination thereof.
In some embodiments, the system further comprises a compressed gas storage storing compressed stored gas at about said first pressure and is in fluid communication with a flow path portion between the compressor and said heat receiving portion. The compressed gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain either (i) a constant volumetric flow rate injection into the nozzle or (ii) a constant output power.
In some embodiments, the system further comprises a compressed gas storage storing compressed gas at about said first pressure and at about said first temperature and is in fluid communication with a flow path portion between the end of the heat receiving portion and the nozzle, including. Namely, the hot compressed gas from the compressed gas storage is in fluid communication with a portion of the flow path downstream the heat receiving portion of the heat exchanger and upstream the nozzle or at times with the nozzle itself. The gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain either (i) a constant volumetric flow rate injection into the nozzle or (ii) a constant output power.
It is to be noted that in some embodiments the compressed gas storage is configured to primarily be filled with compressed gas that is compressed by the compressor of the system. Following the compression of the gas by the compressor, it is directed to fill the compressed gas storage, either in its hot or cold state, namely after or before passing through the heat exchanger. Therefore, the initial setting of the system
may include filling up this compressed gas storage to allow the efficient operation of the system.
In particular, when the HTL temperature is reduced below a desired working temperature, it results in a decrease of the thermal expansion along with the heating, therefore a lower volumetric flow rate enters the nozzle and mixed with the HTL. To maintain a constant flow rate and therefore a constant output power, a compensation of additional gas into the cycle is required and is performed by controlling a valve that is controllably opened and closed based on the temperature of the HTL.
In some embodiments, the system further comprises a temperature sensor that is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL to generate HTL temperature data based thereon, and transmit said HTL temperature data to a controller of the compressed gas storage to control a valve for carrying out said controllable releasing.
In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL in a location along the flow path of the HTL between its ejection from the nozzle and the inlet of the nozzle, namely where the HTL enters the nozzle. Any location between along the above defined flow path is suitable for carrying out the sensing of the temperature of the HTL.
In some embodiments of the system, said temperature sensor is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL between its ejection from the nozzle and its introduction into the nozzle.
In some embodiments of the system, said temperature sensor is configured to sense the temperature of the HTL in the collection unit. Namely, the temperature sensor senses the temperature of the accumulated HTL in the collection unit.
In some embodiments of the system, the temperature sensor is configured to sense the temperature of the HTL at an HTL drain that receives the HTL after its ejection from the nozzle.
In some embodiments of the system, said compressed gas is at about said first pressure and about said second temperature. The compressed gas storage is in fluid communication with said heat receiving portion or a portion upstream thereto. Namely, the compressed gas storage is coupled to a portion of the flow path between the compressor and the heat receiving portion of the heat exchanger.
In some embodiments of the system, said compressed gas is at about said second temperature, wherein the volume flow rate from the compressed gas storage is according to: THTL * Vgas = const, wherein THTL is the temperature of the HTL, Vgas is the volumetric flow rate of the gas that enters the nozzle, and the temperature is in Kelvin units.
In some embodiments of the system, said compressed gas is at about said first pressure and about said first temperature. The compressed gas storage is in fluid communication with said heat removal portion or downstream thereto. Namely, the hot compressed gas from the compressed gas storage is in fluid communication with a portion of the flow path downstream the heat receiving portion of the heat exchanger and upstream the nozzle or at times with the nozzle itself
In some embodiments of the system, the compressed gas storage comprises a controller that is configured for maintaining constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures.
In some embodiments of the system, the nozzle is configured to maintain an equal static pressure at an inlet of the nozzle, or at a mixing volume of the nozzle where the gas and the HTL are mixed, and at the proximal end of the outlet area, which is downstream said mixing volume. In some embodiments, the static pressure is higher than 50% of the stagnation pressure.
In some embodiments of the system, said first temperature, first pressure, second temperature, second pressure and flow rate are within a range of 30% of their nominal value. Namely, there can be deviations of these values to up to 30%.
In some embodiments of the system, the heat source is solar radiation, and the heating volume is configured for receiving heat from solar radiation and transferring it to the HTL.
In some embodiments of the system, the pump is disposed downstream the nozzle and upstream the heating volume.
In some embodiments of the system, the pump is disposed downstream the heating volume and upstream the nozzle.
In some embodiments of the system, the nozzle comprises said heating volume.
In some embodiments of the system, said nozzle comprises a de Laval nozzle supersonic converging-diverging portion, namely a portion defined by an asymmetric hourglass shape. The de Laval nozzle portion is defined between a proximal end and a
distal end, and wherein said de Laval nozzle portion is defined downstream said mixing portion. An optional advantage of the supersonic de Laval nozzle is its high efficiency and high output power due to high mass ratio of the gas/HTL mixture compared to subsonic nozzle.
In some embodiments of the system, the De Laval nozzle cross-section has circular geometry.
In some embodiments of the system, the De Laval nozzle cross-section has rectangular geometry, with round corners.
In some embodiments of the system, the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area. Each maximal cross section pf these portion is defined on a plane normal to the flow direction, namely about a similar maximal horizontal cross section that forms a circular shape. It is to be noted the term "about" in the context of similar cross section means a deviation of up to 20% from a nominal cross section area value. Typically, the maximal cross section of the mixing portion is slightly larger than that of the inlet portion due to the additional volume of the injected gas.
In some embodiments of the system, the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
In some embodiments of the system, the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end. Namely, the maximal cross section of the mixing portion is found at the most downstream portion thereof that borders with the proximal end.
In some embodiments of the system, the turbine comprises said nozzle and the nozzle rotates together with the impeller to produce work. Namely, the ejection of the accelerated mixture through the nozzle causes it to rotate, which results in a generation of work the is used to produce electricity by the rotation.
In some embodiments of the system, the turbine is a reaction turbine.
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 into the nozzle, resulting in an increase of the HTL pressure from about said second pressure to about said first pressure, due to the operation of the reaction turbine. Namely, there is a duct linking between the nozzle and the drain and the ejection of the mixture through
the nozzle generates suction conditions that result in an increase of pressure of the HTL to about the first pressure and its delivery into the nozzle or an inlet of the nozzle.
In some embodiments of the system, the separation unit comprises a curved or circular frame onto which the mixture is ejected. The engagement of the mixture with the curved or circular frame results in a film flow on a surface of the curved or circular frame. The flow on the surface experiences centrifugal force applied by the frame, which results in a separation of the HTL and the gas.
In some embodiments of the system, the heat exchanger is a recuperator.
In some embodiments of the system, a part of the reaction turbine forms said pump.
In some embodiments of the system, the pump is disposed or defined between the drain and the nozzle. Namely, the pump is defined downstream the drain and upstream the nozzle. The centrifugal forces that are generated by the reaction turbine, induce suction conditions that practically act as a pump that pumps the HTL from the drain and deliver it to the nozzle while raising its pressure from about said second pressure to about said first pressure.
In some embodiments of the system, said first pressure is above about 8, 9, 10, 11 or 12 Bar and the first temperature is above about 100°C.
In some embodiments of the system, the second pressure is ambient pressure.
In some embodiments of the system, the second temperature is ambient temperature.
In some embodiments of the system, the flow of the mixture in the nozzle is a supersonic flow.
Any of the above embodiments of the system or any combination thereof can be used in a method according to any of the above embodiments of the method or any combination thereof.
Yet another aspect of the present disclosure provides a nozzle for use in a heat engine. The nozzle comprising an inlet portion for receiving a heat transfer fluid; a mixing portion for mixing the received HTL with gas; and a de Laval nozzle portion, namely 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 said mixing portion and said mixing portion is defined downstream said inlet portion. The de Laval portion is
configured to allow an isothermal expansion of the gas between a first pressure to a second pressure lower than the first pressure.
In some embodiments, the nozzle further comprises an injection port for allowing an injection of gas to the mixing portion.
In some embodiments of the nozzle, the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction, namely about a similar maximal horizontal cross section that forms a circular shape. It is to be noted the term "about" in the context of similar cross section means a deviation of up to 20% from a nominal cross section area value. Typically, the maximal cross section of the mixing portion is slightly larger than that of the inlet portion due to the additional volume of the injected gas.
In some embodiments of the nozzle, the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
In some embodiments of the nozzle, the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end. Namely, the maximal cross section of the mixing portion is found at the most downstream portion thereof the borders with the proximal end.
EMBODIMENTS
The following are optional embodiments and combinations thereof in accordance with aspects of the present disclosure:
1. A method for producing work, comprising: heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering said HTL to an inlet of a nozzle at about a first pressure; compressing gas by a compressor to about said first pressure and heating the compressed gas within a heat receiving portion of a heat exchanger to about said first temperature or lower than about said first temperature; mixing in said nozzle said HTL at said first pressure and said first temperature with the compressed gas at about said first pressure and about said first temperature or
lower than about said first temperature to obtain a gas and HTL mixture, wherein the gas and the HTL in the mixture reaches to about the same temperature after said mixing; allowing the gas in the mixture to undergo isothermal or quasi -isothermal expansion within said nozzle to a second pressure lower than said first pressure, thereby causing acceleration of said mixture towards an outlet of said nozzle; ejecting said mixture through said outlet to produce mechanical work; introducing the ejected gas into a heat removal portion of said heat exchanger to exchange heat with compressed gas exits said compressor; and directing at least a portion of the ejected HTL towards said heating volume.
2. A method according to embodiment 1, wherein said compressing comprises isothermal or quasi-isothermal compression of said gas.
3. A method for realizing a heat engine comprises: introducing heat transfer liquid (HTL) into a nozzle at a first pressure and first temperature; isothermally compressing gas by a compressor from second pressure and second temperature to said first pressure, wherein said second pressure and temperature are lower than said first pressure and first temperature, respectively; heating the compressed gas, exiting the isothermal compressor at a first pressure and a second temperature, by passing it via a heat receiving portion of a counter flow heat exchanger to about said first temperature; injecting the heated gas exiting the heat receiving portion of said heat exchanger into said nozzle to obtain a HTL and gas mixture, thereby causing the mixture to expand isothermally or quasi-isothermally to said second pressure, resulting in acceleration of the mixture in the nozzle; and ejecting the accelerated mixture from an outlet of the nozzle; retrieving the ejected gas at about a second pressure and about a first temperature to a heat removal portion of the heat exchanger for exchanging heat to new compressed gas exiting from the compressor.
4. The method of any one of embodiments 1-3, wherein the gas introduced into the heat exchanger following its ejection from the nozzle is repeatedly isothermally or quasi- isothermally compressed, thereby forming a closed-loop flow of the gas.
5. The method of any one of embodiments 1-3, wherein gas entering the compressor is air at ambient conditions and the gas exiting the heat exchanger after heat removal is discharged to the surrounding.
6. The method of any one of embodiments 1-5, wherein the HTL is selected from a list consisting of: molten salt, thermal oil, ethylene glycol, water, molten metal, or any combination thereof.
7. The method of any one of embodiments 1-6, wherein the gas is one from a list consisting of: air, nitrogen, argon, CO2, or any combination thereof.
8. The method of any one of embodiments 1-7, comprising monitoring the HTL temperature; and controllably releasing gas from a compressed gas storage storing stored gas at about said first pressure and at about said second temperature into a portion of the flow path between the compressor and said heat receiving portion or into said heat receiving portion directly; wherein said controllably releasing is done based on the HTL temperature to obtain a constant volumetric flow rate injection into the nozzle.
9. The method of any one of embodiments 1-8, comprising monitoring the HTL temperature; and controllably releasing gas from a compressed gas storage storing compressed gas at about said first pressure and at about said first temperature into a portion of the flow path between said heat receiving portion and the nozzle or directly into the nozzle; wherein said controllably releasing is done based on the HTL temperature to obtain a constant volumetric flow rate injection into the nozzle.
10. The method of embodiment 9, wherein said stored gas is at about said first pressure and about said second temperature; wherein said controllably releasing comprises releasing the compressed gas into said heat receiving portion.
11. The method of any one of embodiments 8-10, wherein said compressed gas is at about said second temperature or at about said first temperature, wherein the volume flow rate from the gas storage is according to: THTL * Vgas = const, wherein THTL is the temperature of the HTL, Vgas is the volumetric flow rate or the first time-derivative of the volume of the gas enters the nozzle, and the temperature is in Kelvin units.
12. The method of embodiment 9, wherein said compressed gas is at about said first pressure and about said first temperature; wherein said controllably releasing comprises releasing the stored gas downstream the heat receiving portion and upstream the nozzle or directly into the nozzle.
13. The method of any one of embodiments 1-12, comprising maintaining constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures.
14. The method of any one of embodiments 1-13, comprising maintaining equal static pressure at an inlet of the nozzle, or at a mixing area of the nozzle where the HTL is mixed with the gas, and at a proximal end of the outlet area in the nozzle that is higher than 50% of the stagnation pressure.
15. The method of any one of embodiments 1-14, wherein said first temperature, first pressure, second temperature, second pressure, and flow rate are within a range of 30% of their nominal value.
16. The method of any one of embodiments 1-15, wherein said ejecting results in a rotation of the nozzle, thereby producing work.
17. The method of embodiment 16, wherein said nozzle is part of a reaction turbine.
18. The method of embodiment 17, wherein said ejecting is performed in a non-zero velocity that forms a film flow over a surface it is injected onto.
19. The method of any one of embodiment 1-18, comprising separating the HTL from the gas following said ejecting.
20. The method of embodiment 19, wherein said separating comprises directing the ejected mixture onto a curved surface.
21. The method of any one of embodiments 1-20, comprising retrieving a portion of the ejected HTL into the nozzle to undergo another cycle.
22. A system for producing work, comprising: a heating volume for allowing heating heat transfer liquid (HTL) to a first temperature by a heat source; a pump for raising pressure of said HTL to a first pressure at said first temperature; a compressor configured to compress gas to about said first pressure; a heat exchanger in fluid communication with the compressor and configured to receive the compressed gas into a heat receiving portion thereof to allow transfer of heat to the compressed gas to increase its temperature to about said first temperature or lower than about said first temperature;
a nozzle in fluid communication with the heat exchanger and the HTL pump having an inlet portion for receiving said HTL and a mixing portion for (i) allowing mixing said HTL at about said first temperature and at about said first pressure with said gas at about said first temperature or lower than about said first temperature and about said first pressure to obtain a mixture and (ii) allowing said mixture to undergo isothermal expansion to a second pressure lower than said first pressure, thereby causing acceleration of said mixture at said nozzle towards an outlet of the nozzle; a turbine configured for rotation in result to the acceleration of said mixture, thereby converting the kinetic energy of the mixture to work; a separation unit for separating the HTL and the gas, said separation unit comprises a collection unit to collect the ejected HTL and to allow to direct it to either the heating volume, the pump or to the nozzle or towards the nozzle and one of the heating volume or the pump; wherein the separated ejected gas is transferred to a heat removal portion of the heat exchanger to exchange heat with new compressed gas in the heat receiving portion that flows from the compressor.
23. The system of embodiment 22, wherein 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 system of embodiment 22, wherein cooled gas exiting the heat removal portion of the heat exchanger flows to the surrounding, and the compressor is configured to receive gas from the surrounding to compress it to about said first pressure, thereby forming an open system.
25. The system of any one of embodiments 22-24, wherein the HTL is selected from the group consisting of: molten salt, thermal oil, molten metal, ethylene glycol, water, or any combination thereof.
26. The system of any one of embodiments 22-25, wherein the gas is selected from the group consisting of: air, nitrogen, argon, CO2, or any combination thereof.
27. The system of any one of embodiments 22-26, comprising a compressed gas storage storing compressed stored gas at about said first pressure and at about said second temperature and is in fluid communication with a flow path portion between the compressor and said heat receiving portion;
wherein the gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.
28. The system of any one of embodiments 22-27, comprising a compressed gas storage storing compressed gas at about said first pressure and at about said first temperature and is in fluid communication with a flow path portion between the heat receiving portion and the nozzle; wherein the compressed gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.
29. The system of embodiment 27 or 28, comprising a temperature sensor that is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL to generate HTL temperature data based thereon, and transmit said HTL temperature data to a controller of the compressed gas storage to control a valve for carrying out said controllable releasing.
30. The system of embodiment 29, wherein said temperature sensor is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL between its ejection from the nozzle and its introduction into the nozzle.
31. The system of embodiment 29 or 30, wherein said temperature sensor is configured to sense the temperature of the HTL in the collection unit.
32. The system of embodiment 30 or 31, wherein said compressed gas is at about said first pressure and about said second temperature; and wherein said compressed gas storage is in fluid communication with said heat receiving portion.
33. The system of any one of embodiments 30-32, wherein said compressed stored gas is at about said second or first temperature, wherein the volume flow rate from the gas storage is according to: THTL * Vgas = const, wherein THTL is the temperature of the HTL, Vgas 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 units.
34. The system of embodiment 30 or 31, wherein said compressed gas is at about said first pressure and about said first temperature; wherein said gas storage is in fluid communication with a portion of the flow path between said heat receiving portion and the nozzle, or directly with the nozzle.
35. The system of any one of embodiments 30-34, wherein a controller of the compressed gas storage is configured for maintaining constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures.
36. The system of any one of embodiments 22-35, wherein the nozzle is configured to maintain an equal static pressure at an inlet of the nozzle or at a mixing volume where the gas and the HTL are mixed, and at a proximal end portion of an outlet area that is downstream the mixing volume that is higher than 50% of the stagnation pressure.
37. The system of any one of embodiments 22-36, wherein said first temperature, first pressure, second temperature, second pressure and flow rate are within a range of 30% of their nominal value.
38. The system of any one of embodiments 22-37, wherein the heat source is solar radiation, and the heating volume is configured for receiving heat from solar radiation and transfer it to the HTL.
39. The system of any one of embodiments 22-38, wherein the pump is disposed downstream to the nozzle and upstream the heating volume.
40. The system of any one of embodiments 22-39, wherein the pump is disposed downstream the heating volume and upstream the nozzle.
41. The system of any one of embodiments 22-40, wherein the nozzle comprises said heating volume.
42. The system of any one of embodiments 22-41, wherein said nozzle comprises a de Laval nozzle portion defined between a proximal end and a distal end, wherein said de Laval nozzle portion is defined downstream said mixing portion.
43. The system of embodiment 42, wherein the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction.
44. The system of embodiment 43, wherein the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
45. The system of embodiment 43 or 44, wherein the maximal cross section of the mixing portion is common to the maximal cross section of the proximal.
46. The system of any one of embodiments 22-45, wherein the turbine comprises said nozzle and the nozzle rotates together with the turbine to produce work.
47. The system of embodiment 46, wherein said turbine is a reaction turbine.
48. The system of embodiment 47, wherein the collection unit defines a drain for accumulating the separated HTL, and HTL is suctioned from the drain into the nozzle in result to the operation of the reaction turbine, wherein the suctioning causes the HTL to enter the nozzle in about said first pressure.
49. The system of any one of embodiments 22-48, wherein the separation unit comprises a curved or circular frame onto which the mixture is ejected, the engagement of the mixture with the curved or circular frame results in a film flow on a surface of the curved or circular frame.
50. The system of any one of embodiment 22-49 for use in a method according to any one of embodiments 1-21.
51. 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 gas; and a de Laval nozzle portion defined between a proximal end and a distal end; wherein said de Laval nozzle portion is defined downstream said mixing portion and said mixing portion is defined downstream said inlet portion; and wherein said de Laval portion is configured to allow an isothermal expansion of the gas between a first pressure to a second pressure lower than the first pressure.
52. The nozzle of embodiment 51, comprising an injection port for allowing an injection of gas to the mixing portion.
53. The system of embodiment 51 or 52, wherein the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction.
54. The system of embodiment 53, wherein the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%.
55. The system of embodiment 53 or 54, wherein the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end.
56. The method of any one of embodiments 1-21, wherein said delivering or said introducing comprises pressurizing said HTL to about said first pressure.
57. The system of embodiment 47 or 48, wherein a part of the reaction turbine forms said pump.
58. The system of embodiment 57, wherein the pump is disposed or defined between the drain and the nozzle.
59. The system of any one of embodiments 22-49 or 57-58, wherein said first pressure is above about 8 or above 10 Bar and the first temperature is above about 100°C.
60. The system of any one of embodiments 22-49 or 57-59, wherein the flow of the mixture in the nozzle is a supersonic flow.
61. The method of any one of embodiments 1-21, wherein said first pressure is above about 8 Bar or 10 Bar and the first temperature is above about 100°C.
62. The method of any one of embodiments 1-21 or 61, wherein the flow of the mixture in the nozzle is a supersonic flow.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to better understand the subject matter that is disclosed herein and to exemplify 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:
Figs. 1A-1B are block diagrams showing different non-limiting examples of embodiments of a system according to an aspect of the present disclosure.
Fig- 2 shows P-V and T-S diagrams for thermal oil and N2 mixture at 400C.
Figs. 3 is a block diagram showing a non-limiting example of an embodiment of a system according to an aspect of the present disclosure.
Fig- 4 is a schematic illustration of a non-limiting example of a nozzle to be used in a heat engine according to an aspect of the present disclosure.
Figs 5A-5B are schematic illustrations of different views of a non-limiting example of a realization of part of the system, wherein the turbine is a reaction turbine. Fig. 5A is a top view; Fig. 5B is a cross-sectional view.
DETAILED DESCRIPTION
The following figures are provided to exemplify embodiments and realization of the invention of the present disclosure.
Figs. 1A-1B are block diagrams exemplifying non-limiting examples of a system for producing work according to an aspect of the present disclosure. Reference is first being made to Fig. 1A. The system provides a heat engine that is based on an open or closed Ericsson thermodynamic cycle realized on two-phase flow. The system 100 comprises a heating volume 102 that is configured to receive a heat transfer liquid (HTL) from a preheat reservoir 104 and to heat it with heat Qin that is provided by an external heat source. The heat source can be of any type that can heat the HTL, such as waste heat, that is extracted through, for example, flue gas, molten salt, thermal oil or steam. The HTL is heated in the heating volume 102 to a first temperature and is delivered to an input reservoir 106 that is in fluid communication with a nozzle of a turbine 108 and is configured to introduce the heated HTL into the nozzle at a selected and controlled flow rate. The HTL is pressurized to a first pressure prior to the introduction to the nozzle or nozzles, optionally as part of the impeller in a reaction turbine 108. The increase of the pressure of the HTL is performed either in the preheat reservoir 104, the input reservoir 106, by the centrifugal force of the reaction turbine (as described further below), any other location in the flow path between the ejection of the HTL from the turbine and the reintroduction of it through the input reservoir 106, or in two or more of these locations. This is typically performed by a pump (not shown). Therefore, the HTL that is introduced into the nozzle or a few nozzles that are connected or part of the turbine 108, is at a first temperature and a first pressure.
The system further comprises a compressor 110 that is configured to receive gas at a second pressure and compress it to the first pressure. The gas compression by the compressor 110 involves heat Qout exiting the system. Optionally, the compression is isothermal or quasi-isothermal. The compressed gas having a first pressure and a second temperature is directed to a heat receiving portion 111 of a counter-flow heat exchanger 112 of the system 100. The gas is heated in the heat exchanger 112 up to about the first temperature. This is performed by exchanging heat with hot gas that is ejected from the turbine, namely a recuperator, as further explained below.
The gas that exits the heat receiving portion 111 of the counter-flow heat exchanger 112 and is injected into a mixing portion of the nozzle of the turbine 108 to be mixed with the HTL to obtain a gas-HTL-mixture. Therefore, the gas having about a first temperature and a first pressure is mixed with HTL having a first temperature and a first pressure. It is to be noted that there may be a difference of the temperature or the pressure
between the gas and the HTL. For example, the gas can be injected into the turbine at a temperature or pressure that is up to 20% less than the temperature or pressure of the HTL. In the nozzle, the mixture undergoes expansion to a second pressure, lower than the first pressure. In particularly, the gas undergoes an expansion that is isothermal or quasiisothermal as during the expansion, the heat from the HTL, which has a heat capacity much larger than that of the gas, is transferred to the gas and maintain it at about the same temperature. The expansion of the gas results in acceleration of the mixture towards the outlet of the nozzle. The kinetic energy of the accelerated mixture is used for producing work. Typically, the ejected mixture causes the turbine to rotate, making it a reaction turbine, and this rotation results in production of work, i.e. generation of electricity. As mentioned above, the gas and the HTL are ejected from the nozzle at a second pressure, that is lower than the first pressure. The mixture is ejected at about the first temperature and is directed to a heat removal portion 113 of the counter-flow heat exchanger 112 to exchange heat with gas that passes in the heat receiving portion 111 of the counter-flow heat exchanger 112. Therefore, the gas that exits the heat removal portion 113 of the counter-flow heat exchanger 112 is at about a second temperature and about a second pressure. The gas that exits the heat removal portion 113 of the counter flow heat exchanger 112 is directed to the compressor 110 to undergo another cycle in the system. The increase and decrease of the gas temperature in the heat exchangers 112 are done isobarically or close to isobarically.
It is to be noted that in some embodiments of the system, the gas is air and upon its exit from the heat removal portion 113 of the counter-flow heat exchanger 112 it is released to the environment and ambient air is introduced to the compressor 110. Therefore, the system can operate in either a closed or open cycle.
The HTL that is ejected from the nozzle of the turbine 108, or only a portion thereof, is directed to the preheat reservoir 102 to undergo another cycle in the system.
Reference is now being made to Fig. IB, which shows a system that differs from Fig. 1A by further comprising a compressed gas storage 117 and a separation unit 119. There are two optional realization for the compressed gas storage 117. In a first optional realization, the compressed gas storage 117 comprises compressed gas, e.g. air, at about first pressure and at about second temperature, and is linked to the flow path between the compressor 110 and the counter flow heat exchanger 112 so as to release compressed gas into the heat receiving portion of the counter flow heat exchanger 112. In a second
optional realization, the compressed gas storage 117 comprises hot compressed gas, e.g. air, at about first temperature and at about first pressure, and is linked to the flow path between the counter flow heat exchanger 112 and the turbine 108 or the nozzle of the turbine 108 so as to release hot compressed gas downstream the heat receiving portion of the counter flow heat exchanger 112. It is to be noted that in a typical realization of the system, only one of the two alternatives of the compressed gas storage is used. As can be appreciated, the communication of the compressed gas storage 117 with the standard flow path of the system can be a two-directional communication. This allows to fill the compressed gas storage 117 with the compressed gas, either hot or cold, for later use if needed. This step of filling up the compressed gas storage 117 cab take place prior to the standard operation of the system as a preliminary step. A controller (not shown) of the compressed gas storage 117 is configured to control the release of the gas based on the temperature of the HTL that is sensed in a collection unit 121 of the separation unit 119 or in the input reservoir 106. Optionally the compressed gas storage 117 has an input connected from the compressor and an output conduit connected to the heat exchanger. Optionally a controlled valve based on flowmeter and temperature gauges reading, located at the output conduit of the compressed gas storage, controls the flowrate.
The separation unit 119 is configured to separate the gas and the HTL from the HTL and gas mixture following its ejection from the nozzle. For example, the separation unit 119 may include a curved surface onto which the mixture is ejected and the engagement with the surface results in a flow on the surface the experiences centrifugal force that causes a separation between the HTL and the gas. The HTL is collected in a collection unit 121 that defines a drain. A portion of the HTL is delivered back to the preheat reservoir 104 and then to the heating volume 102 to reheat, and part of the HTL is delivered back to the turbine 108 to undergo another cycle. In the embodiment of the system where the turbine 108 is a reaction turbine, namely that the nozzle is rotating due to the ejection of the mixture therefrom to thereby generate electricity, the operation of the turbine 108 causes suction conditions in the drain of the collection unit 121, thereby suctioning HTL from the drain into the nozzle in about first pressure. Also, the portion of the HTL that is delivered to reheat in the heating volume 102 may return to the drain at about the second pressure and pumped back to the nozzle at about the first pressure due to the suction conditions induced by the reaction turbine. This is further exemplified below with respect to Figs 5A-5B.
Optionally, in any one of the above-described embodiments, the working temperature of the nozzle, namely the first temperature is 100°C and above; and the working pressure of the nozzle, namely the first pressure is lOBar and above.
The Ericsson cycle ideally supports Carnot efficiency and the work produced by this system is W = Qin — Qout- Any other thermal losses in the turbine, are optionally maintained as heat in the system. The thermodynamic cycle T-S and P-V diagrams are depicted in Fig. 2.Quasi-isotherml process allows the HTL to cool for a few degrees along with the expansion, while supporting high output power. In general, the HTL can be any liquid carrying heat such as molten metals, molten salt, thermal oil, water, and also liquid with soluble materials such as water with NaCl or ZnCL or NaOH or other soluble materials that are known to raise the boiling point, for example allowing to drive a heat engine on water liquid phase at a temperature higher than 100C.
The gas in the system can be either air, nitrogen, argon, CO2, Helium, or any other gas that is suitable for the realization of such a system.
In some embodiments of the above system, it can be used to provide a constant output power at a constant voltage frequency.
The isobaric heating in the Ericsson cycle maintains the pressure regardless of the HTL temperature. Lower HTL temperature results in a smaller thermal expansion along with the heating and a lower volumetric flow rate of gas injected into the HTL. By increasing the volumetric flowrate the following can be maintained constant: Pgas * l^as=const. 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 low temperature. Optionally, this gas storage is at the compressing low temperature between the compressor and the heat exchanger. Optionally, the storage is between the heat exchanger and the nozzle , for hot gas storage. Controlling the flow rate is done by a valve that is controlled by a control unit that is fed with data of the HTL temperature that is monitored in the system.
Reference is now being made to Fig. 3, which is a block diagram exemplifying an embodiments of the system, in which the heat source is in the form of solar radiation.
In the figures throughout the application, like elements of different figures were given similar reference numerals shifted by the number of hundreds corresponding to the number of the respective figure. For example, element 308 in Fig. 3 serves the same function as element 108 in Fig. 1.
In this non-limiting example, the heating volume 302 is heated by a solar radiation and is part of the turbine 308 or disposed at a proximity to the turbine. Therefore, the HTL circulation can be done at a very low temperature difference due to the minimal head losses. For example, 10 deg, or 50 deg Celsius difference between the HTL entering and exiting the turbine 308. In some embodiments, the turbine comprises the heating volume and the entire HTL capacity is both being cooled by the turbine and heated by solar radiation simultaneously, maintaining a constant average temperature. This allows subdegree temperature reduction. Once there is no available solar radiation as a heat source, the turbine can operate as previously shown in Fig. 1 with hot and cold HTL reservoirs.
Reference is now being made to Fig. 4, which is a schematic illustration 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 of three consecutive portions - an inlet portion 322 that is in fluid communication with a feed of hot and pressurized HTL, a mixing portion 324 that is configured for mixing the HTL with gas injected thereto, and a de Laval portion 326, in which the isothermal expansion occurs. The de Laval portion 326 is extending between a proximal end 328 that borders with the mixing portion 324 and a distal end 330 that typically serves as the outlet of the nozzle. Due to the unique configuration of the system, the inlet portion 322 of the nozzle 320 is allowed to be as broad as desired and at the same pressure as the beginning of the outlet section which has the highest pressure in the nozzle. The inlet portion 322 and the mixing portion 324 have about the same cross section area as a proximal end 328 of the outlet, which typically defines where the maximal area and pressure exist. This also causes that the pressure in the inlet portion 322 and the mixing portion 324 is about the same pressure as in the proximal end 328. The small broadening of cross section of the mixing portion 324 is less than 20% of minimal cross section thereof and is due to the additional volume of the injected gas. Therefore, the maximal horizontal cross section of the inlet portion 322 defined on a first plane Pl and the maximal horizontal cross section of the mixing portion 324 and the proximal end of the de Laval portion 326 defined on a second plane P2 are about the same area, namely less than 20% difference.
Optionally, the De Laval nozzle shape is according to the De-Laval equations as cited in 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 a nozzle was explored for
marine propulsion pressure lower than lObar and temperatures lower than 100C. In contrast to marine propulsion, heat cycles of the present invention operate at maximal pressure and temperature. Fig. 4 is an optional geometry for De Laval two phase flow nozzle for pressure above lOBar and temperature above 100°C. The difference is hidden at the mixture velocities, and the geometry of the nozzle.
Figs. 5A-5B are different views of schematic illustrations of a non-limiting example of a realization of the system and the method of the present disclosure, wherein the turbine is a reaction turbine. The turbine 508 is a 5 nozzles reaction turbine. The turbine 508 comprises a drain 552 that is a part of the collection unit 521. The drain 552 comprises HTL that is collected after ejected from the nozzles. HTL is sucked from the drain 552 into an impeller 554, which creates centrifugal force when rotating. The suction conditions that cause the suction of the HTL into the impeller 554 are due to the operation of the turbine, namely the ejection of the mixture through the nozzle. A portion of the HTL in the drain 552 goes through a heating outlet 553 that directs the HTL to a heating volume in which it is heated. The HTL may pass through a preheating reservoir prior to reaching the heating volume. The reheated HTL is then circulates back through a hot HTL inlet 555 either (i) into the drain 552 or (ii) directly enters the turbine 508 or the impeller 554 without being mixed with the HTL in the drain 552. Gas, such as air or any other suitable gas is supplied optionally through a gas inlet 556 at the center of a shaft 558, and reaching the nozzles 520, located at the peripheral diameter of the impeller 554 having converging-diverging De Laval shape. The acceleration of the mixture drives the turbine 508 and causing the shaft to drive the electromagnetic power generator. The jet of the mixture has a non-zero velocity when exiting the nozzle and is impinging on the circular wall 562 of the housing 564 of the turbine 508 creating a film flow on the walls, which separates the mixture. The HTL flows into the drain 552 to be circulated back into the impeller 554.
If not mentioned differently, the term "about" throughout the application should be interpreted as a deviation of ±20% of the nominal value or from a nominal reference. For example, if the value is about 10, thus it should be understood to be in the range of 8- 12. In another example, if the reference is to a first temperature than it should be understood that the temperature can be in a deviation of ±20% from said first temperature that may be characterized by a temperature of a different material.
Example
Without being bounded to any theory, the following is an example of a controlled volume calculations for Therminol 66 at 400°C and Nitrogen gas (N2) designed for a lOOkW solar receiver according to a realization of the above system.
Considering a volume of N2 in the inertial frame of reference.
Step-1 : Starting with a 3m3 of controlled volume N2 in reaching the compressor at ambient conditions.
P^ = nRTJ => n = 120.272moL => m = 3.367K^ ofN2
According to the ideal gas equation, PV = nRT, increasing the pressure of the gas from approximately 1 Bar to 40 Bar reduces the volume to 0.075m3. When the process is done isothermally, the heat to be removed from the gas to the surrounding is:
Q1 = W1 = P1V1 ln(V/V1) = 1.107M/.
The entropy reduction is dS = Q1/T = 3.69 KJ/K
Step-2: Heating the N2 with oil to 673K at constant pressure.
And the volume is: 0.075m3 * 673K /300K = 0.168m3
Step-3: Approximately isothermal expansion, while generating work;
Q3 = W3 = V3P3 ln(V4/V3) = 0.168m3 * 40Bar * ln(40) = 2.48MJ
The entropy reduction is dS = Q3/T = 3.69 KJ/K.
Step-4: Cooling of the N2 at the heat exchanger Q4 = Q2.
These steps are described by the P-V and T-S diagrams in Fig. 2.
Assuming that the heat loss at the turbine remains in the system for reuse, the practical efficiency is:
This last assumption and calculation reach higher efficiency than the previous isochoric heating cycle, where the heat of the gas exiting is only partially retrieved.
This advantage opens the way for an efficient reaction turbine. Conventionally, due to the non-zero velocity of the HTL exiting the nozzle in a reaction turbine under load, it is considered to be less efficient than an impulse turbine, such as Pelton). However, this loss is converted to heat through friction and is maintained at the turbine for recycling.
Claims
1. A method for producing work, comprising: heating a heat transfer liquid (HTL) to a first temperature within a heating volume and delivering said HTL to an inlet of a nozzle at about a first pressure; compressing gas by a compressor to about said first pressure and heating the compressed gas within a heat receiving portion of a heat exchanger to about said first temperature or lower than about said first temperature; mixing in said nozzle said HTL at said first pressure and said first temperature with the compressed gas at about said first pressure and about said first temperature or lower than about said first temperature to obtain a gas and HTL mixture, wherein the gas and the HTL in the mixture reaches to about the same temperature after said mixing; allowing the gas in the mixture to undergo isothermal or quasi-isothermal expansion within said nozzle to a second pressure lower than said first pressure, thereby causing acceleration of said mixture towards an outlet of said nozzle; ejecting said mixture through said outlet to produce mechanical work; introducing the ejected gas into a heat removal portion of said heat exchanger to exchange heat with compressed gas exits said compressor; and directing at least a portion of the ejected HTL towards said heating volume.
2. A method according to claim 1, wherein said compressing comprises isothermal or quasi-isothermal compression of said gas.
3. A method for realizing a heat engine comprises: introducing heat transfer liquid (HTL) into a nozzle at a first pressure and first temperature; isothermally compressing gas by a compressor from second pressure and second temperature to said first pressure, wherein said second pressure and temperature are lower than said first pressure and first temperature, respectively; heating the compressed gas, exiting the isothermal compressor at a first pressure and a second temperature, by passing it via a heat receiving portion of a counter flow heat exchanger to about said first temperature; injecting the heated gas exiting the heat receiving portion of said heat exchanger into said nozzle to obtain a HTL and gas mixture, thereby causing the mixture to expand isothermally or quasi-isothermally to said second pressure, resulting in acceleration of the mixture in the nozzle; and
ejecting the accelerated mixture from an outlet of the nozzle; retrieving the ejected gas at about a second pressure and about a first temperature to a heat removal portion of the heat exchanger for exchanging heat to new compressed gas exiting from the compressor.
4. The method of any one of claims 1-3, wherein the gas introduced into the heat exchanger following its ejection from the nozzle is repeatedly isothermally or quasi - isothermally compressed, thereby forming a closed-loop flow of the gas.
5. The method of any one of claims 1-3, wherein gas entering the compressor is air at ambient conditions and the gas exiting the heat exchanger after heat removal is discharged to the surrounding.
6. The method of any one of claims 1-5, wherein the HTL is selected from a list consisting of: molten salt, thermal oil, ethylene glycol, water, molten metal, or any combination thereof.
7. The method of any one of claims 1-6, wherein the gas is one from a list consisting of: air, nitrogen, argon, CO2, or any combination thereof.
8. The method of any one of claims 1-7, comprising monitoring the HTL temperature; and controllably releasing gas from a compressed gas storage storing stored gas at about said first pressure and at about said second temperature into a portion of a flow path of the gas between the compressor and said heat receiving portion, or directly into said heat receiving portion; wherein said controllably releasing is done based on the HTL temperature to obtain a constant volumetric flow rate injection into the nozzle.
9. The method of any one of claims 1-8, comprising monitoring the HTL temperature; and controllably releasing gas from a compressed gas storage storing compressed gas at about said first pressure and about at said first temperature into a portion of the flow path between said heat receiving portion and said nozzle, or directly into said nozzle; wherein said controllably releasing is done based on the HTL temperature to obtain a constant volumetric flow rate injection into the nozzle.
10. The method of claim 8 or 9, wherein the volume flow rate from the gas storage is according to: THTL * Vgas = const, wherein THTL is the temperature of the HTL, Vgas is
the volumetric flow rate or the first time-derivative of the volume of the gas enters the nozzle, and the temperature is in Kelvin units.
11. The method of any one of claims 1-10, comprising maintaining constant volumetric flow rate of the gas in the nozzle along a range of HTL operation temperatures.
12. The method of any one of claims 1-11, comprising maintaining equal static pressure at an inlet of the nozzle, or at a mixing area of the nozzle where the HTL is mixed with the gas, and at a proximal end of the outlet area in the nozzle that is higher than 50% of the stagnation pressure.
13. The method of any one of claims 1-12, wherein said ejecting results in a rotation of the nozzle, thereby producing work.
14. The method of claim 13, wherein said nozzle is part of a reaction turbine.
15. The method of claim 14, wherein said ejecting is performed in a non-zero velocity that forms a film flow over a surface it is injected onto.
16. The method of any one of claim 1-15, comprising separating the HTL from the gas following said ejecting.
17. The method of claim 16, wherein said separating comprises directing the ejected mixture onto a curved surface.
18. The method of any one of claims 1-17, comprising retrieving a portion of the ejected HTL into the nozzle to undergo another cycle.
19. The method of any one of claims 1-18, wherein said first pressure is above about 8 Bar and the first temperature is above about 100°C.
20. The method of any one of claims 1-19, wherein the flow of the mixture in the nozzle is a supersonic flow.
21. A system for producing work, comprising: a heating volume for allowing heating heat transfer liquid (HTL) to a first temperature by a heat source; a pump for raising pressure of said HTL to a first pressure at said first temperature; a compressor configured to compress gas to about said first pressure; a heat exchanger in fluid communication with the compressor and configured to receive the compressed gas into a heat receiving portion thereof to allow transfer of heat to the compressed gas to increase its temperature to about said first temperature or lower than about said first temperature;
a nozzle in fluid communication with the heat exchanger and the HTL pump having an inlet portion for receiving said HTL and a mixing portion for (i) allowing mixing said HTL at about said first temperature and at about said first pressure with said gas at about said first temperature or lower than about said first temperature and about said first pressure to obtain a mixture and (ii) allowing said mixture to undergo isothermal expansion to a second pressure lower than said first pressure, thereby causing acceleration of said mixture at said nozzle towards an outlet of the nozzle; a turbine configured for rotation in result to the acceleration of said mixture, thereby converting the kinetic energy of the mixture to work; a separation unit for separating the HTL and the gas, said separation unit comprises a collection unit to collect the ejected HTL and to allow to direct it to either the heating volume, the pump or to the nozzle or towards the nozzle and one of the heating volume or the pump; wherein the separated ejected gas is transferred to a heat removal portion of the heat exchanger to exchange heat with new compressed gas in the heat receiving portion that flows from the compressor.
22. The system of claim 21, wherein cooled gas exiting the heat removal portion of the heat exchanger flows towards the compressor, thereby forming a closed-loop flow of the gas.
23. The system of claim 21, wherein cooled gas exiting the heat removal portion of the heat exchanger flows to the surrounding, and the compressor is configured to receive gas from the surrounding to compress it to about said first pressure, thereby forming an open system.
24. The system of any one of claims 21-23, wherein the HTL is selected from the group consisting of: molten salt, thermal oil, molten metal, ethylene glycol, water, or any combination thereof.
25. The system of any one of claims 21-24, wherein the gas is selected from the group consisting of: air, nitrogen, argon, CO2, or any combination thereof.
26. The system of any one of claims 21-25, comprising a compressed gas storage storing compressed stored gas at about said first pressure and at about said second temperature and is in fluid communication with a flow path portion between the compressor and said heat receiving portion, or directly with said heat receiving portion;
wherein the gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.
27. The system of any one of claims 21-26, comprising a compressed gas storage storing compressed stored gas at about said first pressure and at about said first temperature and is in fluid communication with a flow path portion between the said heat receiving portion and said nozzle, or directly with said nozzle; wherein the gas storage is configured for controllably releasing gas based on a sensed temperature of the HTL to obtain a constant volumetric flow rate injection into the nozzle.
28. The system of claim 26 or 27, comprising a temperature sensor that is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL to generate HTL temperature data based thereon, and transmit said HTL temperature data to a controller of the gas storage to control a valve for carrying out said controllable releasing.
29. The system of claim 28, wherein said temperature sensor is configured to sense the temperature of the HTL in at least one location along the flow path of the HTL between its ejection from the nozzle and its introduction into the nozzle.
30. The system of claim 28 or 29, wherein said temperature sensor is configured to sense the temperature of the HTL in the collection unit.
31. The system of any one of claims 21-30, wherein the nozzle is configured to maintain an equal static pressure at an inlet of the nozzle or at a mixing volume where the gas and the HTL are mixed, and at a proximal end portion of an outlet area that is downstream the mixing volume that is higher than 50% of the stagnation pressure.
32. The system of any one of claims 21-31, wherein the heat source is solar radiation, and the heating volume is configured for receiving heat from solar radiation and transfer it to the HTL.
33. The system of any one of claims 21-32, wherein the pump is disposed downstream to the nozzle and upstream the heating volume.
34. The system of any one of claims 21-32, wherein the pump is disposed downstream the heating volume and upstream the nozzle.
35. The system of any one of claims 21-34, wherein the nozzle comprises said heating volume.
36. The system of any one of claims 21-35, wherein said nozzle comprises a de Laval nozzle portion defined between a proximal end and a distal end, wherein said de Laval nozzle portion is defined downstream said mixing portion.
37. The system of claim 36, wherein the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction; wherein the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%; and wherein the maximal cross section of the mixing portion is common to the maximal cross section of the proximal.
38. The system of any one of claims 21-37, wherein the turbine comprises said nozzle and the nozzle rotates together with the turbine to produce work.
39. The system of claim 38, wherein said turbine is a reaction turbine.
40. The system of claim 39, wherein the collection unit defines a drain for accumulating the separated HTL, and HTL is suctioned from the drain into the nozzle in result to the operation of the reaction turbine, wherein the suctioning causes the HTL to enter the nozzle in about said first pressure.
41. The system of claim 39 or 40, wherein a part of the reaction turbine forms said pump.
42. The system of any one of claims 21-41, wherein the separation unit comprises a curved or circular frame onto which the mixture is ejected, the engagement of the mixture with the curved or circular frame results in a film flow on a surface of the curved or circular frame.
43. The system of any one of claims 21-42, wherein said first pressure is above about 8 Bar and the first temperature is above about 100°C.
44. The system of any one of claims 21-43, wherein the flow of the mixture in the nozzle is a supersonic flow.
45. The system of any one of claim 21-44 for use in a method according to any one of claims 1-20.
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 gas; and
a de Laval nozzle portion defined between a proximal end and a distal end; wherein said de Laval nozzle portion is defined downstream said mixing portion and said mixing portion is defined downstream said inlet portion; and wherein said de Laval portion is configured to allow an isothermal expansion of the gas between a first pressure to a second pressure lower than the first pressure.
47. The nozzle of claim 46, comprising an injection port for allowing an injection of gas to the mixing portion.
48. The system of claim 46 or 47, wherein the inlet portion, the mixing portion, and the proximal end of the de Laval nozzle portion are all having about a similar maximal cross section area, wherein each maximal cross section is defined on a plane normal to the flow direction; wherein the maximal cross section of the mixing portion is larger than that of the inlet portion by up to 20%; and wherein the maximal cross section of the mixing portion is common to the maximal cross section of the proximal end.
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WO2022049573A2 (en) | 2020-09-04 | 2022-03-10 | Technion Research & Development Foundation Limited | Heat engine |
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US3972195A (en) * | 1973-12-14 | 1976-08-03 | Biphase Engines, Inc. | Two-phase engine |
US4984432A (en) * | 1989-10-20 | 1991-01-15 | Corey John A | Ericsson cycle machine |
US20130276447A1 (en) * | 2010-12-30 | 2013-10-24 | C3Tech Chaix & Associes, Consultants En Technologies | Device for converting heat energy into mechanical energy |
WO2021151109A1 (en) * | 2020-01-20 | 2021-07-29 | Mark Christopher Benson | Liquid flooded closed cycle |
WO2022049573A2 (en) | 2020-09-04 | 2022-03-10 | Technion Research & Development Foundation Limited | Heat engine |
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