Energy storage and recovery system and method

Abstract

Various energy storage and recovery systems, and methods of various energy storage and recovery are disclosed. Wherein one system comprises a thermal energy storage subsystem, a trilateral cycle, a first heat exchanger and a second heat exchanger; the first heat exchanger exchanges heat between the heat storage medium and the working fluid, and the second heat exchanger exchanges heat on the high-pressure side and the low-pressure side of the three-side circulation. Another system includes a conduit fluidly connecting pressurized gases in the low and high temperature heat storage tanks and through a heat exchanger, where the gases in the conduit exchange heat with the heat storage medium and / or the working fluid, thereby enabling recovery of heat lost due to evaporation of the heat storage medium when thermal energy stored in the system is discharged; the methods involve various operations of the system.

Description

Technical Field

[0001] The present invention relates to the field of energy storage and recovery. More specifically, embodiments of the present invention relate to methods and systems for thermal energy storage and recovery using an improved trilateral cycle and / or heat recovery during heat discharge / energy recovery. Background Art

[0002] There is a great need for cheap energy storage and recovery. The cost of fossil fuels and hydrocarbon gases is high, and their stocks are low, especially in Europe. This has an extraordinary impact on electricity prices and supply, especially in times of high demand.

[0003] Carbon dioxide is a readily available, inexpensive material. There is an urgent need to find new uses for carbon dioxide, at least in part to remove it from the Earth's atmosphere.

[0004] When the high-temperature storage tank in the heat storage system is emptied, the pressure in the tank drops, and part of the heat storage medium (usually liquid phase) evaporates. When the heat storage medium evaporates, the heat of evaporation will be very large, and this evaporation heat will reduce the heat storage capacity of the system.

[0005] This “Background” section provides background information only. Statements in this “Background” section are not an admission that the subject matter disclosed in this “Background” section constitutes prior art to the present application, and no part of this “Background” section shall be used as an admission that any part of the present application, including this “Background” section, constitutes prior art to the present application. Summary of the invention

[0006] Embodiments of the present invention relate to methods and systems for thermal energy storage and recovery. In one aspect, the present invention relates to an energy storage and recovery system, including a thermal energy storage subsystem and a new and improved thermodynamic cycle, wherein the thermal energy storage subsystem includes: a high-temperature thermal storage tank storing a thermal storage medium at a first temperature, one or more first pressure change devices configured to transfer the thermal storage medium between the high-temperature thermal storage tank and a thermal storage medium source, and a first heat exchanger through which the thermal storage medium is to pass;

[0007] The first heat exchanger is configured to exchange heat between the heat storage medium and the working fluid (in a thermodynamic cycle) within a first temperature range; the thermodynamic cycle contains the working fluid and has a high pressure side and a low pressure side, the thermodynamic cycle includes a compressor / expander configured to change the pressure of the working fluid between the high pressure side and the low pressure side of the thermodynamic cycle, a second heat exchanger, a substantially isothermal heat exchanger through which the working fluid passes, and one or more second pressure changing devices, the second pressure changing devices being configured to transfer the working fluid from the substantially isothermal heat exchanger to the second heat exchanger when the energy storage and recovery system recovers energy (or is referred to as discharge), and to transfer the working fluid from the second heat exchanger to the second heat exchanger when the energy storage and recovery system stores energy (or is referred to as charging). transported to a substantially isothermal heat exchanger; the substantially isothermal heat exchanger is configured to exchange heat between a working fluid and a heat storage medium or an external environment at a substantially constant temperature, wherein the substantially isothermal heat exchanger is in fluid communication with a second heat exchanger; the first heat exchanger may include a high temperature gradient heat exchanger; the second heat exchanger is configured to: (i) transfer excess heat on the high-pressure side of the thermodynamic cycle to the low-pressure side of the thermodynamic cycle and preheat the working fluid to be compressed by the compressor / expander when storing energy, and (ii) transfer heat from the working fluid expanded by the compressor / expander on the low-pressure side of the thermodynamic cycle to the high-pressure side of the thermodynamic cycle when recovering energy; the thermodynamic cycle includes a three-sided cycle (e.g., an improved three-sided cycle with internal superheat transfer).

[0008] In some embodiments, the thermal storage medium may come from a low temperature thermal storage tank that stores the thermal storage medium at a second temperature that is lower than the first temperature and greater than a substantially constant temperature. In other embodiments, the thermal storage medium may come from an external environment, such as the external atmosphere or a large body of water (e.g., a large man-made tank or pool, a natural body of water, such as a lake, river, bay, basin, ocean, etc.).

[0009] In other or further embodiments, there is pressurized gas in the high temperature heat storage tank and the low temperature heat storage tank, and the energy storage and recovery system further comprises a first conduit (e.g., one or more conduits) connecting the pressurized gas in the low temperature heat storage tank and the pressurized gas in the high temperature heat storage tank. Typically, the first conduit is configured to balance (e.g., partially or completely balance) a first pressure in the high temperature heat storage tank with a second pressure in the low temperature heat storage tank. In one example, the first conduit may pass through at least a first heat exchanger, and the pressurized gas in the first conduit may exchange heat with the heat storage medium and / or working fluid in the first heat exchanger.

[0010] In various embodiments, the second heat exchanger may include one or more low temperature gradient heat exchangers configured to exchange heat within a second temperature range lower than the first temperature range. In one example, the second heat exchanger includes a low temperature gradient heat exchanger configured to exchange heat between the heat storage medium and the working fluid within the second temperature range at the high pressure side and the low pressure side of the thermodynamic cycle. In another example, the second heat exchanger includes a first low temperature gradient heat exchanger and a second low temperature gradient heat exchanger, wherein the first low temperature gradient heat exchanger is configured to exchange heat between the heat storage medium and the working fluid on the high pressure side of the thermodynamic cycle, and the second low temperature gradient heat exchanger is configured to exchange heat between the high pressure side and the low pressure side of the thermodynamic cycle.

[0011] In some embodiments, the thermal storage medium includes water. In other or further embodiments, the working fluid includes carbon dioxide, but the present invention is not limited to using water as the thermal storage medium or using carbon dioxide as the working fluid.

[0012] In some embodiments, the first pressure changing device may include a reversible propeller pump. In other embodiments, the first pressure changing device may include a conventional one-way pump (e.g., a circulation pump), and a turbine connected in parallel with the one-way pump. The one-way pump is configured to move the heat storage medium from the source of the heat storage medium to the high-temperature heat storage tank when the energy storage and recovery system is charged (storing energy), and the turbine is configured to convert the flow of the heat storage medium into another form of energy (e.g., electrical energy, rotational mechanical energy, etc.) when the energy storage and recovery system is discharged (recovering energy). In these other embodiments, the first pressure changing device may further include first and second three-way valves located upstream and downstream of the one-way pump and the turbine, which are configured to control the flow direction of the heat storage medium when the system is charged and / or discharged, and an optional second one-way pump, which is configured to move the heat storage medium from the high-temperature heat storage tank to the turbine or move the heat storage medium from the turbine to the source of the heat storage medium when the energy storage and recovery system is discharged. The second one-way pump is advantageous when the system includes a conduit connecting the low-temperature and high-temperature heat storage tanks. Alternatively, the first pressure changing device may include a first one-way pump and a second one-way pump, which are configured to move the heat storage medium in a first direction when the system is filled (for example, from the high temperature heat storage tank to the source of the heat storage medium), and move in a second direction opposite to the first direction when the system is discharged.

[0013] In other or further embodiments, the second pressure changing device may include a first pump and a second one-way pump, wherein the first pump is configured to deliver the working fluid from the substantially isothermal heat exchanger to the gradient heat exchanger when the energy storage and recovery system is discharged, and the second one-way pump is configured to deliver the working fluid from the gradient heat exchanger to the substantially isothermal heat exchanger when the energy storage and recovery system is filled. Alternatively, instead of the second one-way pump, the second pressure changing device may include a turbine disposed between the gradient heat exchanger and the substantially isothermal heat exchanger, and the turbine is driven by the working fluid when the energy storage and recovery system is filled.

[0014] In one specific application, the present invention relates to a submarine, comprising the energy storage and recovery system of the present invention, and a shell, the shell at least surrounding a high temperature heat storage tank, a first and a second heat exchanger, a first and a second pressure change device, and a compressor / expander. The shell may further surround a low temperature heat storage tank, and in some embodiments, the substantially isothermal heat exchanger may be located in the shell or in thermal contact with the shell. The submarine can use the thermal energy stored in the high temperature heat storage tank for air-independent propulsion (AIP) or aerodynamics, and the submarine can be a nuclear-powered or non-nuclear-powered submarine.

[0015] In another aspect, the present invention relates to a thermal energy storage and recovery system, comprising: a low-temperature heat storage tank for storing a heat storage medium at a second temperature and containing a pressurized gas therein; a high-temperature heat storage tank for storing a heat storage medium at a first temperature higher than the second temperature and containing a pressurized gas therein; one or more first pressure change devices configured to transfer the heat storage medium between the low-temperature heat storage tank and the high-temperature heat storage tank; a first heat exchanger through which the heat storage medium passes; a first conduit for (i) fluidly connecting the pressurized gas in the low-temperature heat storage tank with the pressurized gas in the high-temperature heat storage tank and (ii) passing through the first heat exchanger; and a thermodynamic cycle; the first heat exchanger is configured to exchange heat between the heat storage medium and a working fluid in the thermodynamic cycle; the pressurized gas in the first conduit is connected to the heat storage medium in the first heat exchanger; The thermodynamic cycle includes a second heat exchanger configured to exchange heat between the working fluid and an external environment or a heat source / sink, a compressor / expander in fluid communication with the first heat exchanger and (directly or indirectly) the second heat exchanger, and one or more second pressure changing devices located between the first heat exchanger and the second heat exchanger and in fluid communication therewith; the compressor / expander is configured to change the pressure of the working fluid between the first heat exchanger and the second heat exchanger; the second pressure changing device is configured to: transfer the working fluid from the second heat exchanger to the first heat exchanger when the thermal energy storage and recovery system is discharged (recovering energy), and transfer the working fluid from the first heat exchanger to the second heat exchanger when the energy storage and recovery system is charged (storing energy). In various embodiments, the thermodynamic cycle includes a Brayton cycle or a trilateral cycle, any of which can be further combined with another of a Rankine cycle, a Stirling cycle or a Brayton cycle or a trilateral cycle.

[0016] In some advantageous embodiments, the heat storage medium may include water, and / or the second heat exchanger may include a substantially isothermal heat exchanger, as described above / herein. In further embodiments, the energy storage and recovery system further includes one or more first valves configured to open and close the first conduit, and the low temperature heat storage tank and the high temperature heat storage tank each have one or more vents or second valves; the vents or second valves may be configured to reduce the pressure of the pressurized gas in the low temperature heat storage tank or the high temperature heat storage tank.

[0017] In an energy storage and recovery system including a first conduit, when the energy storage and recovery system is discharged (recovering energy), the pressurized gas in the first conduit can recover a first amount of heat from the thermal storage medium and / or the working fluid, and the thermal storage medium can lose a second amount of heat due to evaporation in the high-temperature thermal storage tank (for example, in the absence of the first conduit); the first amount of heat offsets at least a portion of the second amount of heat. Additionally or alternatively, the high-temperature thermal storage tank is sometimes in a partially filled, partially discharged state, and the length of time is sufficient to allow the thermal storage medium to vaporize in an otherwise identical system in which the high-temperature thermal storage tank is closed or sealed. For example, the length of time can be at least four (4) hours, eight (8) hours, or another value, during which the pressurized gas in the first conduit recovers a sufficient amount of heat from the thermal storage medium and / or the working fluid to offset at least half of the heat lost due to evaporation of the thermal storage medium in the high-temperature thermal storage tank.

[0018] Another aspect of the present invention relates to a method for recovering heat when a heat storage medium is discharged from a high-temperature heat storage tank, comprising: adding gas to the high-temperature heat storage tank and the low-temperature heat storage tank in fluid communication with the high-temperature heat storage tank for pressurization; discharging the heat storage medium from the high-temperature heat storage tank to the low-temperature heat storage tank, and when discharging the heat storage medium, allowing the heat storage medium to flow through one or more heat exchangers in fluid communication between the high-temperature heat storage tank and the low-temperature heat storage tank; and allowing the pressurized gas to flow through a first conduit in fluid communication with the low-temperature heat storage tank and the high-temperature heat storage tank, the first conduit passing through at least one of the one or more heat exchangers; the high-temperature heat storage tank stores the heat storage medium at a first temperature, and the low-temperature heat storage tank stores the heat storage medium at a second temperature lower than the first temperature; the pressurized gas in the first conduit exchanges heat with the heat storage medium, thereby recovering at least part of the heat when the heat storage medium is discharged.

[0019] In some embodiments, discharging the thermal storage medium includes pumping the thermal storage medium from the high temperature thermal storage tank to the low temperature thermal storage tank; or, discharging the thermal storage medium may include driving a turbine with the flow of the thermal storage medium. Further embodiments of the method may include discharging heat from the thermal storage medium to a working fluid in a thermodynamic cycle (e.g., a trilateral cycle or a Brayton cycle) located in a heat exchanger when discharging the thermal storage medium.

[0020] Beneficial Effects: The present system and method can use carbon dioxide as a working fluid and water as a storage medium. Water and carbon dioxide are both cheap and abundant, and water is environmentally friendly. Water is an advantageous heat storage medium because its heat capacity is relatively large (e.g., compared to other materials that are in the liquid phase at ambient temperature).

[0021] The tanks used to store the medium can be relatively simple and inexpensive, since the thermal storage medium can be stored and used at relatively low temperatures and moderate pressures. The system can include as few as two tanks, but remain independent of the environment, or as few as one tank while using the external environment as a heat source / sink.

[0022] Other advantages of the present invention will become apparent from the following detailed description of various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a temperature-entropy (TS) diagram showing an improved trilateral cycle of carbon dioxide (CO 2 ) according to an embodiment of the present invention.

[0024] Figure 2 is a schematic diagram of an exemplary system according to the present invention, including a three-sided expansion-heat exchange-compression-heat exchange cycle and a thermal energy storage subsystem including pressure-equalized low-temperature and high-temperature storage tanks.

[0025] Figure 3 is similar to Figure 2 Schematic diagram of an exemplary system including a three-sided expansion-heat exchange-compression-heat exchange cycle and a thermal energy storage subsystem including pressure-equalized low-temperature and high-temperature storage tanks.

[0026] Figure 4 An exemplary single tank energy storage subsystem is shown, which is similar to Figure 2 The exemplary three-sided loops shown work in conjunction. DETAILED DESCRIPTION

[0027] One or more embodiments of the present invention will now be described in detail, examples of which are illustrated in the accompanying drawings. Although the present invention will be described together with the following embodiments, it should be understood that these descriptions are not intended to limit the present invention to these embodiments. On the contrary, the present invention is intended to encompass substitutions, modifications and equivalents that may be included within the spirit and scope of the present invention.

[0028] In addition, in the detailed description below, in order to provide a comprehensive understanding of the present invention, many specific details are listed. However, it will be readily apparent to those skilled in the art that the present invention can be implemented without these specific details. In other cases, well-known methods, procedures, and components are not described in detail in order to avoid unnecessarily obscuring various aspects of the present invention. In addition, it should be understood that the possible permutations and combinations described herein are not meant to limit the present invention. Specifically, inconsistent variations can be mixed and matched as desired.

[0029] The technical solution of the embodiment of the present invention will be Figure 1It is to be understood that the present invention is not limited to these embodiments. Based on the embodiments described in the present invention, those skilled in the art can obtain other embodiments without creative contributions, and within the scope of legal protection of the present invention.

[0030] In addition, except for mutually exclusive features and / or processes, all features, measures or processes disclosed in this document may be combined in any manner and in any possible combination. Unless otherwise stated, any feature disclosed in this specification, claims, abstract and drawings may be replaced by other equivalent features or features with similar goals, purposes and / or functions.

[0031] For convenience and simplicity, "part", "local" and "region" are used interchangeably herein, but are generally given their art-recognized meanings. Whenever one of the terms is used, it includes the other terms. In addition, unless otherwise indicated in the context of use herein, the terms "known", "fixed", "given", "determined" and "predetermined" generally refer to values, quantities, parameters, constraints, conditions, states, processes, procedures, methods, practices or combinations thereof that are theoretically variable but are generally set in advance and do not change after use.

[0032] The term "ambient temperature", which may also be referred to as room temperature, generally refers to a temperature in the range of 15-30° C. (eg, 18-25° C., or any temperature or temperature range therein).

[0033] Energy Storage and Recovery System Embodiments

[0034] Figure 1 A temperature and entropy diagram of a trilateral cycle 100 using carbon dioxide as the working fluid and including internal superheat transfer Q5-6 is shown. The trilateral cycle 100 can be used to store thermoelectric energy in a liquid such as water. Figure 1 In the three-sided cycle (referred to as the cycle), 1-2 represents a process in which the temperature of the working fluid is slightly increased but the entropy is not changed, 2-3 and 3-4 represent an isobaric temperature increase gradient heat exchange process, 4-5 represents an adiabatic expansion process, 5-6 represents an isobaric temperature decrease gradient heat exchange process, and 6-1 represents an isothermal heat exchange process (i.e., heat transfer to another medium; for example, due to the phase change of the working fluid from gas to liquid at 0°C in the cycle). The heat added to the cycle from the heat source is Qin=Q8-9+Q9-10. The heat transferred from the cycle (for example, to the radiator) is Qout=Q5-6+Q6-1. The mechanical power added to the cycle is Win=W1-2. The mechanical power generated by the system and / or transferred within the system is Wout=W16.

[0035] The three-side cycle 100 is reversible. Therefore, Figure 1The diagram also shows a three-sided heat pump cycle, with the heat source at a constant temperature of 0°C and a gradient radiator when the heat pump runs in the opposite direction (counterclockwise). In the reverse cycle, 6-5 is an isobaric temperature increase gradient heat exchange process, 5-4 is an adiabatic compression heat exchange process, 4-3-2 is an isobaric temperature decrease gradient heat exchange process, 2-1 is a pressure recovery process, and 1-6 is an isothermal and isobaric heat exchange process (such as changing from liquid phase to gas phase). The heat added to the cycle from the heat source is Qin = Q1-6 + Q6-5. The heat output from the cycle to the radiator is Qout = Q4-3 + Q3-2. The mechanical power added to the cycle is Win = W5-4 (i.e., -W16). The mechanical power output of the cycle is Wout = W2-1 (i.e., -W1-2).

[0036] The trilateral cycle utilizes the different specific heats of carbon dioxide in different temperature ranges. For example, at a relatively high given pressure (e.g., 124.5 bar, Figure 1 As shown in Figure 2, the specific heat of carbon dioxide from 7°C to 100°C is 274 kJ / kg, which is about 83% higher than that at temperatures between 100 and 208 ar (150 kJ / kg). In addition, the higher the working fluid pressure, the more linear the gradient curve (as shown in Figure 2). Figure 1 2-4), the more constant the specific heat of the working fluid.

[0037] In addition, when the working fluid is carbon dioxide, the expansion ratio in the trilateral cycle 100 is 1:2.6, while for other working fluids, such as dimethyl ether (DME) or pentane, the expansion ratio is much higher (e.g., >1:10, and in the case of dimethyl ether, up to 1:36). The expansion ratio is the ratio of the pressure in the low-pressure heat exchange process 5-6 to the pressure in the high-pressure heat exchange process 2-3-4. Therefore, the expansion process 4-5 and the compression process 5-4 can be completed in one step (e.g., using a single-stage reversible expander / compressor).

[0038] The present invention also relates to a method and a system for thermal energy storage and recovery. Figure 2 An exemplary system 110 is shown, which includes a thermal energy storage subsystem 120 and an improved three-sided heat engine / heat pump 130. The thermal energy storage subsystem 120 includes a low-temperature heat storage tank 11 and a high-temperature heat storage tank 12, a pipe or other conduit 13 for connecting the internal vertices of the low-temperature heat storage tank 11 and the high-temperature heat storage tank 12 and a bidirectional pump 14, and the bidirectional pump 14 is used to transfer a thermal storage medium 22 between the low-temperature heat storage tank 11 and the high-temperature heat storage tank 12. The thermal storage medium 22 can be (or contain) water. The high-temperature heat storage tank 12 can store the thermal storage medium 22 at a relatively high temperature (e.g., 100-300°C, or any temperature or temperature range therein, such as 200-250°C). The thermal storage medium 22 can be stored in the low-temperature heat storage tank 11 at a relatively low temperature (e.g., 0-50°C, or any temperature or temperature range therein).

[0039] Typically, the conduit 13 is used to equalize the pressure of the gas in the low-temperature heat storage tank 11 and the high-temperature heat storage tank 12. For example, the pressure of the pressurized gas in the heat storage tanks 11 and 12 may be 2 to 40 bar, or any pressure or pressure range therein (e.g., 15 to 20 bar), but the present invention is not limited to this range. In addition, in various embodiments, there may be a valve (not shown) in each of the heat storage tanks 11 and 12, which is configured to discharge or release excess gas pressure in the tank and / or open the heat storage tank to atmospheric pressure, and a valve is configured in the conduit 13 to open and close the conduit 13. For example, when the gas pressure of the heat storage tanks 11 and 12 is greater than 1 atmospheric pressure, the valve in the conduit 13 may be closed and the valve on the heat storage tank 11 or 12 may be opened, and the excess pressure in the other heat storage tank may be used to help drive the heat storage medium 22, so that the heat storage medium 22 flows from the high-pressure heat storage tank to the low-pressure heat storage tank, thereby reducing the pressure and wear on the pump 14.

[0040] Three-side heat engine / heat pump 130 realization Figure 1 The three-sided loop 100 is shown. Figure 2 The identification numbers 1 to 6 correspond to Figure 1 Points 1 to 6 in the trilateral cycle 100. The pressure recovery-isothermal heat exchange-gradient heat exchange-compression-gradient heat exchange cycle 2-1-6-5-4-3-2 (energy storage, or charging) and the reverse cycle 2-3-4-5-6-1-2 (energy recovery, or discharge) can use carbon dioxide as the working fluid, and other fluids with similar thermal properties (e.g., specific heat, thermal expansion coefficient, condensation and / or evaporation [latent heat], etc.) can also be applicable. For example, ethylene glycol can be added to the heat storage medium, which can extend the temperature range to below 0°C.

[0041] refer to Figure 2 The three-sided cycle 130 includes first and second gradient heat exchangers 17 and 15, a reversible expander / compressor 16, an isothermal heat exchanger 23 that may be further equipped with a circulation device 18, and a reversible pump 19. The circulation device 18 may include a fan, a mixer (e.g., having two or more blades radially arranged around a rotating shaft), a pump, etc. The reversible pump 19 may include a gear pump, a screw pump (e.g., a three-screw positive displacement rotary pump sold under the IMO trademark, commercially available from CIRCOR International, Inc., Monroe, NC) or a similar reversible device.

[0042] Heat exchangers 15 and 17 exchange heat between the working fluid and the heat storage medium 22 in the trilateral cycle 130. Heat exchanger 17 also performs internal heat exchange between different segments of the trilateral cycle 130 (i.e., the working fluid in gradient heat exchange 2-3 or 3-2 exchanges heat with the working fluid in gradient heat exchange 5-6 or 6-5, respectively). Due to the heat exchange between different segments of the trilateral cycle 130, nodes 3 and 5 ( Figure 1 Nodes 3 and 5 in the three-sided loop 100 are at the same temperature. Figure 1 In the case of , the temperature of nodes 3 and 5 is 100°C, but this temperature may be different in different working fluids, or the same working fluid at different pressures.

[0043] refer to Figure 2 When the system 110 stores energy, the heat storage medium 22 in the thermal energy storage subsystem 120 is pumped from the low-temperature heat storage tank 11 to the high-temperature heat storage tank 12 by the bidirectional pump 14 through the heat exchanger 17 and the heat exchanger 15. In the three-sided cycle 130, the working fluid passes through the heat exchangers 15 and 17 at the position of 4-3-2 (i.e., in the opposite direction of the heat storage medium 22) and discharges heat to the heat storage medium 22. In the heat exchangers 15 and 17, the working fluid is at a relatively high pressure and supercritical phase. Then, the pump 19 pumps the working fluid through the isothermal heat exchanger 23 and the heat exchanger 17 at 1-6-5. In the pump 19 (or an equivalent device described herein), the working fluid changes from the supercritical phase to a liquid. The isothermal heat exchanger 23 has a temperature at which the working fluid changes from a liquid to a gas again. In heat exchanger 17, the working fluid passing through heat exchanger 17 at 6-5 (i.e., the low pressure section of cycle 130) absorbs heat from the working fluid at 3-2 (i.e., the high pressure section of cycle 130). At 5-4, the working fluid is heated by compressor / expander 16 from a relatively low pressure (e.g., 34.9 bar, e.g., Figure 1 The working fluid is also heated by compression, from a relatively low temperature (such as 100°C, as shown in Figure 1 As shown) is heated to a relatively high temperature (such as 208°C).

[0044] In some embodiments, a turbine or throttle valve (not shown) may be configured in parallel with the pump 19, with first and second three-way valves (also not shown) directing the working fluid through the pump 19 or turbine / throttle valve in the three-sided cycle 130. The turbine may drive power generation or other forms of usable energy (e.g., mechanical energy), and the throttle valve may regulate and / or maintain the pressure of the working fluid on the low-pressure side of the cycle 130, thereby maintaining constant inlet conditions for expansion. It does this by introducing a flow restriction, causing a significant local pressure drop in the fluid.

[0045] When the system is discharged, the bidirectional pump 14 moves the heat storage medium 22 from the high-temperature heat storage tank 12 to the low-temperature heat storage tank 11 through the heat exchangers 15 and 17, and the working fluid is pumped by the pump 19 through the heat exchangers 17 and 15, wherein the heat storage medium 22 discharges the stored heat into the working fluid (when carbon dioxide is used as the working fluid, it is in a supercritical phase at 2-3-4 of cycle 130).

[0046] The working fluid then drives the mechanical energy recovery process (e.g., by expansion) in the expander / compressor 16, transitions from the supercritical phase to the gas phase, and then discharges the remaining heat in the heat exchanger 17 (at 5-6) to the working fluid in the high-pressure section of the cycle 130 (i.e., 2-3). The working fluid then passes through the isothermal heat exchanger 23, where it undergoes a phase change (e.g., from gas to liquid), thereby discharging additional heat. In some embodiments, the medium from which the working fluid in the isothermal heat exchanger 23 discharges heat is the external environment (e.g., the external atmosphere; a large body of water, such as a lake, sea, bay, basin, river, etc.). When the medium in the isothermal heat exchanger 23 is the external atmosphere (e.g., the air outside or above a building), the heat storage medium 22 can pass through one or more conduits in the external / outdoor air (e.g., it can be thermally connected to multiple cooling fins). The circulation device 18 can help circulate the isothermal medium to help maintain its constant temperature.

[0047] When the working fluid is carbon dioxide, its high density at 0°C means that the isothermal heat exchanger 23 can be relatively compact, having a relatively small surface area. In addition, when maintained at 0°C, the medium to which the working fluid in the isothermal heat exchanger 23 rejects heat can be a relatively large water tank containing liquid water and ice. The ice can be maintained in its icy state by periodically adding ice to the isothermal exchange medium (and optionally extracting liquid water from the isothermal exchange medium) or by externally cooling the tank (for example, using a conventional refrigeration system or a Peltier cooler).

[0048] However, the working fluid is not limited to carbon dioxide, and the medium temperature in the isothermal heat exchanger 23 is not limited to 0°C. One of the advantages of the current improved trilateral cycle is that the 5-6 / 6-5 ( Figure 1 ) results in a small compression / expansion ratio, which in turn results in a relatively high pressure at 6-1 / 1-6 (e.g., in isothermal heat exchanger 23; see Figure 2-3 ). Therefore, the isothermal heat exchanger 23 can benefit from a relatively compact design. In addition, when discharged, the working fluid (or working medium) in the gradient heat exchangers 15 and 17 is kept at a constant temperature over the entire temperature range of 100 to 208°C ( Figure 1 ) receives heat from the heat storage medium 22, plus additional heat in the temperature range of 0 to 100°C generated by superheating from the low-pressure section of cycle 130.

[0049] In addition, when Figure 2When the high temperature heat storage tank 12 in the system is emptied, the pressure in the high temperature heat storage tank 12 drops, and part of the (generally liquid) heat storage medium 22 evaporates. When the heat storage medium 22 evaporates, the heat of evaporation may be significant, which reduces the effectiveness of the system.

[0050] In order to increase the useful thermal energy in the system 110, the low temperature heat storage tank 11 and the high temperature heat storage tank 12 can be pressurized with the gas 24 therein. The upper parts of the low temperature and high temperature heat storage tanks 11 and 12 are connected to the conduit 13. When the pressure in the high temperature heat storage tank 12 is reduced (for example, when the heat storage medium 22 is pumped or transported from the high temperature heat storage tank 12), the pressurized gas 24 flows from the low temperature heat storage tank 11 to the high temperature heat storage tank 12. Therefore, in its simplest form, the pressure of the low temperature heat storage tank 11 and the high temperature heat storage tank 12 is substantially the same. Therefore, the power consumed by the pump 14 pumping the heat storage medium 22 between the low temperature heat storage tank 11 and the high temperature heat storage tank 12 is much less than when there is no pressurized gas 24. For example, the pump 14 can include a single reversible propeller pump or a reversible flow pump, which only needs to overcome the friction loss in the pipeline between the low temperature heat storage tank 11 and the high temperature heat storage tank 12. In a more specific embodiment, the reversible propeller pump includes a relatively precise variable speed control to optimize its operation. Alternatively, the reversible pump 14 may include first and second parallel low-pressure one-way circulation pumps configured to select the flow direction using first and second three-way valves upstream and downstream of the parallel pumps. This dual pump design can be seen in U.S. Patent Application No. 18 / 337,561 filed on June 20, 2023, the relevant parts of which are incorporated into this application by reference.

[0051] In various improved embodiments, a pressure sensor (not shown) may be provided in the conduit 13 to monitor and / or measure the pressure of the gas 24, and additional pressurized gas may be added to the conduit 13 or the low-temperature heat storage tank 11 (e.g., for safety reasons) through a valve, and / or one or more pressure-activated valves (e.g., between one of the heat storage tanks 11 or 12 and the conduit 13) may be controlled to control when (e.g., when the pressure difference across the valve exceeds a predetermined value, such as within the range of 1 to 10 atm) the pressurized gas 24 is transferred from one heat storage tank to another. On the other hand, when water flows from the low-temperature heat storage tank 11 to the high-temperature heat storage tank 12, the pressure in the low-temperature heat storage tank 11 decreases, and the pressurized gas 24 flows from the high-temperature heat storage tank 12 to the low-temperature heat storage tank 11 to balance the pressures in each heat storage tank.

[0052] When the high temperature heat storage tank 12 is galvanized or coated with a protective layer, the pressurized gas 24 may be air. When the high temperature heat storage tank 12 is made of steel, the pressurized gas 24 may be an inert gas, such as nitrogen or argon, to prevent corrosion of the steel.

[0053] Energy storage and recovery system embodiments with heat recovery

[0054] like Figure 3 The advantageous embodiment shown, in which the pressurized gas 24 can be heated or cooled when the gas 24 flows between the low temperature heat storage tank 11 and the high temperature heat storage tank 12. The pressurized gas 24 passes through the heat exchangers 15' and 17' and can be heated or cooled together with the working medium (i.e., the working fluid in the cycle 130). Each of the heat exchangers 15' and 17' may include a gradient heat exchanger disclosed in U.S. Patent Application No. 18 / 337,561 filed on June 20, 2023, the relevant portions of which are incorporated herein by reference. However, in Figure 3 In the illustrated thermal energy storage and recovery system 200, the heat exchanger 17' is optional.

[0055] Figure 3 The exemplary system 200 in the embodiment includes a low-temperature heat storage tank 11 storing a heat storage medium 20 at a second temperature, a high-temperature heat storage tank 12 storing the heat storage medium at a first temperature higher than the second temperature, one or more first pressure changing devices (e.g., a reversible pump 14 configured to transfer the heat storage medium 20 between the low-temperature heat storage tank 11 and the high-temperature heat storage tank 12), a first heat exchanger 15' through which the heat storage medium 20 passes, a first conduit 13', and a thermodynamic cycle or heat engine (e.g., a trilateral cycle 130).

[0056] The three-sided cycle 130 includes a working fluid, a second heat exchanger 23 configured to exchange heat between the working fluid and an external environment or a heat source / sink, a compressor / expander 16 fluidly connected to the first heat exchanger 15' and (directly or indirectly) the second heat exchanger 23, and one or more second pressure changing devices (e.g., a reversible pump 19) that are (directly or indirectly) in fluid communication with the first heat exchanger 15' and the second heat exchanger 23. The compressor / expander 16 is configured to change the pressure of the working fluid between the first heat exchanger 15' and the second heat exchanger 23.

[0057] The pump 19 is configured to transfer the working fluid from the second heat exchanger 23 to the first heat exchanger 15' (or the third heat exchanger 17' connected in series with the first heat exchanger 15') when the heat storage and recovery system 200 recovers heat (or is called discharge), and to transfer the working fluid from the first heat exchanger 15' (or the third heat exchanger 17') to the second heat exchanger 23 when the heat storage and recovery system 200 stores energy (or is called charging). The first heat exchanger 15' is configured to exchange heat between the heat storage medium 20 and the working fluid in the trilateral cycle 130. The third heat exchanger 17' is an optional heat exchanger in the system 200, and is used to exchange heat between the heat storage medium 20 and the working fluid on the high-pressure side and the low-pressure side of the trilateral cycle 130.

[0058] There is pressurized gas 24 in the low temperature heat storage tank 11 and the high temperature heat storage tank 12. The first conduit 13' connects the pressurized gas 24 in the low temperature heat storage tank 11 with the pressurized gas 24 in the high temperature heat storage tank 12, and passes through the first heat exchanger 15' and the optional third heat exchanger 17'. In the first heat exchanger 15' and the third heat exchanger 17', the pressurized gas 24 in the first conduit 13' exchanges heat with the heat storage medium 20 and the working fluid in the thermodynamic cycle 130. In some embodiments, the conduit 13' passes only through the first heat exchanger 15'. In such an embodiment, when the thermodynamic cycle 130 includes the third heat exchanger 17' and the system 200 is storing energy (or charging), the pressurized gas 24 flows from the high temperature heat storage tank 12 to the low temperature heat storage tank 11 and enters the low temperature heat storage tank 11 when the temperature is higher than the second temperature (i.e., the temperature of the heat storage medium 20 in the low temperature heat storage tank 11). This may slightly increase the second temperature, but when the low-temperature heat storage tank 11 is large enough, it may have substantially no effect on the second temperature.

[0059] In various embodiments, the thermodynamic cycle or heat engine in the system 200 may include a Brayton cycle instead of the trilateral cycle 130. Either the Brayton cycle or the trilateral cycle may be further combined with a Rankine cycle, a Stirling cycle, or another cycle of the Brayton cycle and the trilateral cycle. As is known in the art, each of these thermodynamic cycles has at least one heat exchanger configured to exchange heat between a working fluid and an external environment or a heat source / sink, at least one heat exchanger that can be configured to exchange heat between a working fluid and a heat storage medium, a compressor / expander fluidly connected to the heat exchanger, and one or more pressure changing devices that change the pressure of the working fluid in the opposite direction to the pressure of the compressor / expander. However, at least one of the Rankine cycle and the Stirling cycle has a substantially isothermal heat exchanger.

[0060] When the thermal energy storage and recovery system 200 recovers heat, the pressurized gas 24 in the conduit 13' can recover the first heat from the heat storage medium 22 and / or the working fluid. In certain configurations of the first and third heat exchangers 15' and 17', the conduit 13' may be in thermal contact with one of the heat storage medium 22 and the working fluid, but not (or less) in contact with the other medium. When the heat storage medium 22 is discharged from the high-temperature heat storage tank 12, the heat storage medium 22 may lose a second heat in the high-temperature heat storage tank 12 due to evaporation. In the absence of the first conduit, this second heat may be considerable. For example, the heat of evaporation of water at 208°C and 1900kPa (about 18.75atm) is 1907.9kJ / kg. In the system 200, the first heat recovered by the pressurized gas 24 in the conduit 13' at least offsets a portion of the second heat lost due to the vaporization of the heat storage medium 22.

[0061] When the high-temperature heat storage tank 12 is not sufficiently filled for a long time, the pressurized gas 24 in the heat storage tank 12 is saturated with the vapor (e.g., water) of the heat storage medium 22. However, this heat (e.g., heat of evaporation) is not lost because it is returned to the heat storage medium in the tank 12 by the pressurized gas 24 in the conduit 13' through the heat exchanger 15' (optionally the heat exchanger 17') during the filling. On the other hand, if the evaporation of the heat storage medium 22 in the heat storage tank 12 is negligible and the heat removal speed of the medium is fast enough (e.g., there is a relatively short cycle time between the heat removal and heat storage processes), there is no need to install a heat exchanger at the gas connection (i.e., through the conduit 13' through the heat exchangers 15' and 17'), Figure 2 The system 110 in may be advantageous because installing a heat exchanger at the gas connection places certain physical limitations on the design of the system.

[0062] However, the vaporization of the liquid phase material is not necessarily an instantaneous process. When the high temperature heat storage tank 12 is in a state of partial energy storage, partial discharge and the time for evaporating the heat storage medium 22 is long enough, the heat loss caused by evaporating the liquid phase heat storage medium 22 is more significant. Therefore, in an otherwise identical system, when the high temperature heat storage tank is closed or sealed (such as when the conduit 13' is missing), the heat loss is more significant. Therefore, in some embodiments, the pressurized gas 24 in the conduit 13' recovers a sufficient amount of heat from the heat storage medium 22 and / or the working fluid to offset at least half of the heat lost in the high temperature heat storage tank 22 due to the evaporation of the heat storage medium 22 in the absence of the conduit 13'. For example, the length of time can be at least four (4) hours, eight (8) hours, or another value, during which the heat loss caused by the evaporation of the heat storage medium 22 is large enough to justify the recovery of the lost heat.

[0063] In various embodiments, the heat exchanger 23 exchanges heat between the working fluid and an external environment or a heat source / sink. In some embodiments, the working fluid exchanges heat in the heat exchanger 23 with an external environment, such as the external and / or ambient atmosphere, a large body of water, such as a lake, pond, river, ocean, etc., or a thermally stable underground heat reservoir. In some embodiments, the working fluid exchanges heat in the heat exchanger 23 with a heat source / sink, such as an artificial pool (e.g., containing water), a large block of concrete, a composite structure (e.g., a high-rise building or skyscraper) that includes both a thermally conductive material (e.g., steel or aluminum) and an insulator (e.g., concrete, glass, brick, and / or stone), etc. Figure 2 System 110 in Figure 3 The heat exchanger 23 in may further include a circulation device 18 as described herein.

[0064] In some advantageous embodiments, as described herein, the thermal storage medium 22 may include water, and the heat exchanger 23 may include a substantially isothermal heat exchanger. In further embodiments, the thermal energy storage and recovery system 200 further includes one or more valves (not shown) configured to open and close the conduit 13', and / or one or more vents or valves (not shown) on the low temperature thermal storage tank 11 and the high temperature thermal storage tank 12. The valves may be configured to add gas (e.g., air, nitrogen, argon, etc.) to the corresponding thermal storage tank 11 or 12, and the vents or valves of the above-mentioned thermal storage tanks may be configured to reduce the pressure of the pressurized gas 24 in the corresponding thermal storage tank 11 or 12 (e.g., for safety purposes).

[0065] In embodiments where the pressure difference between the high-pressure side and the low-pressure side of the thermodynamic cycle / heat engine 130 is sufficiently low (e.g., an expansion ratio <10:1), the second pressure changing device may include a reversible pump 19. However, in embodiments where the pressure difference between the high-pressure side and the low-pressure side of the thermodynamic cycle / heat engine 130 is sufficiently high (e.g., an expansion ratio >10:1), the second pressure changing device may include a conventional one-way pump (e.g., a circulation pump) configured to move the working fluid from the heat exchanger 23 to the first or third heat exchanger 15' or 17' when the energy storage and recovery system 200 stores energy; and a turbine connected in parallel with the one-way pump, configured to convert the flow of the working fluid into another form of energy (e.g., electrical energy, rotational mechanical energy, etc.) when the energy storage and recovery system 200 recovers energy. In such embodiments, the thermodynamic cycle / heat engine 130 may further include first and second three-way valves upstream and downstream of the one-way pump and the turbine, configured to control the flow direction of the working fluid when the system is filled (storing energy) and / or discharged (recovering energy).

[0066] Alternatively, in order to prevent the heat storage medium 22 from evaporating and the generated steam from mixing with the pressurized gas 24 in the high-temperature heat storage tank 12, a layer of floating body or a layer of liquid that does not mix with the medium 22 and has a lower density than the medium 22 may be covered on the surface of the heat storage medium 22. For example, when the medium 22 includes water, the floating body or liquid layer may include silicone oil, or paraffin whose temperature is lower than the working temperature of the high-temperature heat storage tank 12.

[0067] Single Tank Energy Storage and Recovery System Embodiment

[0068] Figure 4 A single tank or dual tank system 300 is shown, which is based on Figure 2 and 3 The principle operation of the system shown. Figure 4 The system and Figure 2The system 110 is similar, except that the low temperature thermal storage tank 311 can be a large capacity water storage tank, or a man-made or natural water body, such as a pond, lake, river, sea or ocean, or even the external atmosphere (see Figure 2-3 ). Figure 2 The gradient heat exchanger 15 in the illustrated system 110 is divided into a low temperature gradient heat exchanger 315 and an internal (gradient) heat exchanger 325. Therefore, Figure 2 The pressure balance conduit 13 in Figure 4 The low temperature heat storage tank 311 should be at least several times (e.g., at least 3-5 times) larger than the high temperature heat storage tank 312, and the relative size may depend on the combined cost of the heat storage tanks 311 and 312. When the low temperature heat storage tank 311 is a body of water or the external atmosphere, the heat exchanger 323 in the trilateral cycle 330 does not need to be close to (e.g., in thermal contact with) a similar heat exchanger in the thermal energy storage subsystem 320.

[0069] exist Figure 4 In the system 300, the low-temperature heat storage tank 311 is self-pressurized during the filling (energy storage) process. Therefore, when the high-temperature heat storage tank 312 discharges the heat storage medium 322, the heat storage medium 322 can drive the first turbine (not shown). Conversely, during the filling process, the tri-lateral cycle 330 can drive a second turbine (not shown), which is configured in parallel with the pump 319 (but with opposite flow). During operation, the first and second turbines respectively drive the pump 319 or 314 in another subsystem (i.e., the tri-lateral cycle 330 or the thermal energy storage subsystem 320). The configuration of the first and second turbines can further include first and second valves (not shown), which respectively connect the pipelines of each pump and turbine in the subsystem, and can be configured to guide the respective medium to flow through the pump or turbine. Such valves can include conventional manual or electronic control valves.

[0070] Figure 4 The thermal energy storage subsystem 320 includes a high-temperature heat storage tank 312 , first and second gradient heat exchangers 315 and 317 , a pump 314 and a low-temperature heat storage tank 311 . Figure 4 The trilateral cycle 330 in the embodiment includes a bidirectional expander / compressor 316, an isothermal (or substantially isothermal) heat exchanger 323 located at or passing through the low-temperature heat storage tank 311, a pump 319, first and second gradient heat exchangers 315 and 317, and a third gradient heat exchanger 325. The first and second gradient heat exchangers 315 and 317 exchange heat between the heat storage medium 322 in the thermal energy storage subsystem 320 and the working fluid on the high-pressure side of the trilateral cycle 330. The third gradient heat exchanger 325 exchanges heat between the working fluid on the high-pressure side of the trilateral cycle 330 and the working fluid on the low-pressure side of the trilateral cycle 330, and is therefore an "internal" heat exchanger.

[0071] Figure 4The three-side loop 330 in Figure 2 and Figure 3 The working principle of the trilateral cycle 130 in FIG. 1 is basically the same, except that the ratio of the working fluid flowing through the internal gradient heat exchanger 325 in the trilateral cycle 330 relative to the high-pressure gradient heat exchanger 315 is controlled, so that the internal heat exchange process can be distinguished from the heat exchange process with the heat storage medium 322 in the trilateral cycle 330. The design 300 in this embodiment is configured with the internal gradient heat exchanger 325 and the low-temperature high-pressure gradient heat exchanger 315, which is Figure 2 An alternative to design 110 is that design 110 is configured with only the low temperature heat exchanger 17 .

[0072] Determining and controlling the proportion of working fluid transferred from the first gradient heat exchanger 315 to the internal gradient heat exchanger 325 in the tri-lateral cycle 330 is within the state of the art. Figure 1 , where the working fluid is carbon dioxide, the heat Q8-9 transferred to / from the carbon dioxide in the first gradient heat exchanger 315 (at 2A-3A or 3A-2A) is 156 kJ / kg, and the heat Q5-6 transferred to / from the high-pressure carbon dioxide in the internal gradient heat exchanger 325 (at 2B-3B or 3B-2B) is 121 kJ / kg. The amount of carbon dioxide passing through the first gradient heat exchanger 315 relative to the amount of carbon dioxide passing through the high-pressure side of the internal gradient heat exchanger 325 on the high-pressure side of the trilateral cycle 330 can be proportional to the heat transfer. Therefore, in a relatively simple design, the conduits in and out of the gradient heat exchangers 315 and 325 can be relatively simple T-joints or Y-joints, and the cross-sectional area of ​​the conduits for transporting carbon dioxide in and out of the first gradient heat exchanger 315 relative to the cross-sectional area of ​​the conduits in and out of the internal gradient heat exchanger 325 can be the ratio of the heat transfer (i.e., Q8-9 to Q5-6, or about 9:7 in this example). A constant pressure is maintained at the high-pressure end of the tripartite cycle 330, and the relative cross-sectional area ratio between the conduit connecting the high-temperature heat exchanger 317 and the pump 319 and the upstream or downstream connection of the heat exchangers 315 and 325 is equal to the ratio of the cross-sectional areas of all conduits for carbon dioxide to enter and exit the first gradient heat exchanger 315 and the internal gradient heat exchanger 325 (in this case, 10).

[0073] In the high temperature heat exchanger 317, the heat capacity of the working fluid is significantly lower (e.g., on average) than the heat capacity in the first (low temperature) heat exchanger 315. For example, when using carbon dioxide at a pressure of 124.5 bar as the working fluid, the heat capacity of the low temperature heat exchanger 315 ranges from 2.19 to 1.80 kJ / kg-K (corresponding to a temperature range of 7 to 100°C), while the heat capacity of the high temperature heat exchanger 317 ranges from 1.80 to 1.22 kJ / kg-K (corresponding to a temperature range of 100 to 208°C). Therefore, in the low temperature heat exchanger 315 (i.e., Q8-9), the heat transferred out / through by carbon dioxide is 274 kJ / kg, while in the high temperature heat exchanger 317 (i.e., Q9-10), the heat transferred out / through by carbon dioxide is 150 kJ / kg.

[0074] Application examples of this system

[0075] An application of the present systems 110, 200 and 300 ( Figure 2-4 ) is an air independent propulsion (AIP) system that can be used in submarines. For example, certain non-nuclear submarines used by Sweden, Japan, and Singapore (e.g., certain Gotland-class, Södermöland-class, and Archer-class submarines manufactured and / or modified by Saab Kockums AB, a company located in Malmö, Sweden) are equipped with Stirling engines for underwater power generation. The Stirling engines in such submarines can be replaced with a 110, 200, or 300 thermal energy storage and recovery system. For example, storing 300 cubic meters of high-temperature water in the high-temperature heat storage tank 12 or 312 can enable such a submarine to operate underwater for 14 days with the same power output as the Stirling engine it replaces. By omitting the low-temperature heat storage tank 11, Figure 4 The system 300 will be Figure 2 , Figure 3 The systems 110 and 200 in the present invention are slightly smaller and can use seawater as the heat storage medium (optionally, seawater that has been filtered and / or purified to eliminate particles exceeding a predetermined minimum size and / or sterilize microorganisms such as bacteria, viruses, mold, fungi, etc.). The present thermal energy storage and recovery systems 110, 200 or 300 can also be used to store thermal energy generated by a nuclear power plant on a nuclear submarine.

[0076] Thus, a submarine may include the present thermal energy storage and recovery system and a housing that surrounds at least the above-mentioned high temperature heat storage tank, the first and second heat exchangers, the first and second pressure changing devices, and the compressor / expander. In some embodiments, the housing may further enclose the low temperature heat storage tank therein. In other or further embodiments, the substantially isothermal heat exchanger may be located in the above-mentioned housing or in thermal contact with the housing. The submarine may include other components or assemblies that are typically found on submarines, such as one or more propellers, one or more sources of stored air or oxygen, one or more fuel storage tanks, one or more propulsion mechanisms, one or more control systems, one or more communication systems, one or more living and / or sleeping cabins, etc.

[0077] Exemplary methods for recovering heat losses in a thermal energy recovery process

[0078] The present invention relates to a method for recovering heat when a high-temperature heat storage tank discharges a heat storage medium, wherein the heat storage medium is a heat storage medium 22 ( Figure 3 ). For example, the method may include pressurizing the gas 24 in the high temperature heat storage tank 12 and the low temperature heat storage tank 11; discharging the heat storage medium 22 from the high temperature heat storage tank 12 to the low temperature heat storage tank 11, passing the heat storage medium 22 through one or more heat exchangers, such as heat exchanger 15' and optional heat exchanger 17', when discharging the heat storage medium 22; and transmitting the pressurized gas 24 through a conduit 13' that fluidly connects the low temperature heat storage tank 11 to the high temperature heat storage tank 12. The conduit 13' is located at or passes through at least one of the heat exchangers 15' and 17'. The high temperature heat storage tank 12 stores the heat storage medium 22 at a first temperature, and the low temperature heat storage tank 11 stores the heat storage medium 22 at a second, lower temperature. The pressurized gas 24 in the conduit 13' exchanges heat with the heat storage medium 22 and / or the working fluid in the thermodynamic cycle / heat engine 130, thereby recovering at least part of the heat when the heat storage medium 22 is discharged.

[0079] The method is performed in accordance with the operation (e.g., heat recovery) of the thermal energy storage and recovery system 220 described herein. Thus, in some embodiments, the discharge of the thermal storage medium may include pumping the thermal storage medium 22 from the high temperature thermal storage tank 12 to the low temperature thermal storage tank 11 using the pump 14. Alternatively, discharging the thermal storage medium may include driving a turbine (not shown) with the flow of the thermal storage medium 22. The flow of the thermal storage medium 22 may be driven through the turbine from upstream (e.g., at 8) or downstream of the turbine using a one-way pump (not shown). A further embodiment of the method may include discharging heat from the thermal storage medium 22 to a working fluid in a thermodynamic cycle / heat engine 130 in a heat exchanger 15' (and optionally in a heat exchanger 17') when discharging the thermal storage medium 22.

[0080] When the system 200 includes a valve in the conduit 13', the method may further include opening the valve in the conduit 13' before discharging the heat storage medium 22 from the high-temperature heat storage tank 12, or confirming that the valve in the conduit 13' is open. In addition, when the system 200 includes a vent or valve in the high-temperature heat storage tank 12, the method may further include confirming that the vent or valve in the high-temperature heat storage tank 12 is in a closed state, or closing the vent or valve in the high-temperature heat storage tank 12 before discharging the heat storage medium 22 from the high-temperature heat storage tank 12.

[0081] Exemplary methods of thermal energy storage and recovery

[0082] The present invention also relates to the use Figure 2 System 110 in Figure 3 System 200 or Figure 4 A method for storing thermal energy using the system 300 in the embodiment of the present invention. The method may include: storing a thermal storage medium 22 in a low temperature thermal storage tank 11, passing the thermal storage medium 22 through first and second gradient heat exchangers 15 / 15' and 17 / 17', compressing a working fluid (e.g., in a thermodynamic cycle or heat engine 130), passing the compressed working fluid through first and second gradient heat exchangers 15 / 15' and 17 / 17', discharging heat from the compressed working fluid to the thermal storage medium 22 in the first and second gradient heat exchangers 15 / 15' and 17 / 17', discharging heat from the compressed working fluid to the uncompressed working fluid in the second gradient heat exchanger 17 / 17', and storing the heated thermal storage medium 22 in a high temperature thermal storage tank 12; and exchanging heat between the working fluid and a heat source / heat tank (e.g., an external environment) at a substantially constant temperature. Discharging heat from the compressed working fluid to the thermal storage medium 22 effectively heats the thermal storage medium 22 and cools the compressed working fluid. The heat exchange between the working fluid and the heat source / sink at a substantially constant temperature effectively changes the phase of the working fluid (eg, from a supercritical phase to a liquid).

[0083] Some embodiments of the method may further include adding pressurized gas 24 to each of the low temperature heat storage tank 11 and the high temperature heat storage tank 12, and then balancing the pressure of the gas 24 in the low temperature and high temperature heat storage tanks 11 and 12. This balancing may include opening a conduit 13 / 13' in fluid communication with the tanks 11 and 12.

[0084] In other or further embodiments of the method, heat from the compressed working fluid may be rejected to the thermal storage medium 22 by pumping the thermal storage medium 22 through the first and second gradient heat exchangers 15 / 15' and 17 / 17' using a pump (e.g., a reversible pump 14), and / or by driving a turbine (e.g., in a thermodynamic cycle or heat engine 130) with the cooled compressed working fluid. Other aspects of the method of storing thermal energy may include or relate to the operation or function of the above-described systems 110, 200, and / or 300.

[0085] The present invention also relates to a method for recovering energy, comprising storing a heat storage medium 22 at a second, higher temperature in a high-temperature heat storage tank 12, passing the heat storage medium 22 through first and second gradient heat exchangers 15 / 15' and 17 / 17', passing a working fluid through first and second gradient heat exchangers 15 / 15' and 17 / 17', discharging heat from the heat storage medium 22 to the working fluid in the first and second gradient heat exchangers 15 / 15' and 17 / 17', thereby heating the working fluid and cooling the heat storage medium 22, storing the cooled heat storage medium 22 in a low-temperature heat storage tank 11, and expanding the heated working fluid (for example, in a thermodynamic cycle / heat engine 130); discharging heat from the expanded working fluid into the compressed working fluid in the second gradient heat exchanger 17 / 17', and performing heat exchange between the expanded working fluid and the heat source / heat sink at a substantially constant temperature, thereby changing the phase of the expanded working fluid (for example, from a gas phase to a liquid phase).

[0086] Some embodiments of the method may further include using conduit 13 / 13' to balance the pressure of pressurized gas 24 in the high temperature thermal storage tank 12 with the pressurized gas 24 in the low temperature thermal storage tank 11, and recovering heat from the working fluid and / or thermal storage medium 22 when discharged from the system 110, 200 or 300 (similar to the method of storing thermal energy). Other or further aspects of the method may further include using the cooled thermal storage medium 22 to drive a turbine before storing the cooled thermal storage medium 22 in the low temperature thermal storage tank 11. When driving the turbine, the method of recovering energy may also include closing a valve in conduit 13 / 13' before the thermal storage medium is discharged from the system 110, 200 or 300 (e.g., passing the thermal storage medium 22 through the first and second gradient heat exchangers 15 / 15' and 17 / 17').

[0087] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and it is apparent that many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling those skilled in the art to best utilize the invention and various embodiments with various modifications suitable for the particular use contemplated.

Claims

1. An energy storage and recovery system, characterized in that: include: A high temperature heat storage tank storing a heat storage medium at a first temperature; one or more first pressure varying devices configured to transfer the thermal storage medium between the high temperature thermal storage tank and a source of the thermal storage medium; a first heat exchanger, the heat storage medium passing through the first heat exchanger, the first heat exchanger being configured to exchange heat between the heat storage medium and a working fluid within a first temperature range; and A thermodynamic cycle containing a working fluid and having a high pressure side and a low pressure side, the thermodynamic cycle comprising: A compressor / expander configured to change the pressure of a working fluid between a high pressure side and a low pressure side of a thermodynamic cycle; a second heat exchanger configured to (i) transfer excess heat from the high-pressure side of the thermodynamic cycle to the low-pressure side of the thermodynamic cycle and preheat the working fluid to be compressed by the compressor / expander during charging, and (ii) transfer heat from the working fluid expanded by the compressor / expander on the low-pressure side of the thermodynamic cycle to the high-pressure side of the thermodynamic cycle during energy recovery; a substantially isothermal heat exchanger through which a working fluid passes, configured to exchange heat at a substantially constant temperature between the working fluid and a thermal storage medium or an external environment, wherein the substantially isothermal heat exchanger is in fluid communication with a second heat exchanger; and One or more second pressure varying devices configured to transfer the working fluid from the substantially isothermal heat exchanger to the second heat exchanger when the energy storage and recovery system recovers energy, and to transfer the working fluid from the second heat exchanger to the substantially isothermal heat exchanger when the energy storage and recovery system stores energy.

2. The energy storage and recovery system according to claim 1, characterized in that The source of the thermal storage medium includes a low temperature thermal storage tank that stores the thermal storage medium at a second temperature that is lower than a first temperature and greater than a substantially constant temperature.

3. The energy storage and recovery system according to claim 2, characterized in that The high-temperature heat storage tank and the low-temperature heat storage tank both have pressurized gas, and the energy storage and recovery system further includes a first conduit, which connects the pressurized gas in the low-temperature heat storage tank with the pressurized gas fluid in the high-temperature heat storage tank.

4. The energy storage and recovery system according to claim 3, characterized in that The first conduit at least passes through the first heat exchanger, and the pressurized gas in the first conduit exchanges heat with the heat storage medium and / or the working fluid through the first heat exchanger.

5. The energy storage and recovery system according to claim 3, characterized in that The first conduit is configured to balance a first pressure in the high temperature heat storage tank with a second pressure in the low temperature heat storage tank.

6. The energy storage and recovery system according to claim 1, characterized in that The heat storage medium includes water.

7. The energy storage and recovery system according to claim 1, characterized in that The working fluid includes carbon dioxide.

8. The energy storage and recovery system according to claim 1, characterized in that One or more of said first pressure varying devices comprises a first reversible pump.

9. The energy storage and recovery system according to claim 8, characterized in that One or more of said second pressure varying means comprises a second reversible pump.

10. The energy storage and recovery system according to claim 1, characterized in that The thermodynamic cycle includes a three-sided cycle.

11. A thermal energy storage and recovery system, characterized in that: include: a low temperature heat storage tank storing a heat storage medium at a second temperature and having pressurized gas therein; a high temperature heat storage tank storing the heat storage medium at a first temperature higher than a second temperature and having pressurized gas therein; one or more first pressure changing devices configured to transfer the heat storage medium between the low-temperature heat storage tank and the high-temperature heat storage tank; a first heat exchanger through which the heat storage medium passes, the first heat exchanger being configured to exchange heat between the heat storage medium and a working fluid; a first conduit configured to (i) connect the pressurized gas in the low-temperature heat storage tank to the pressurized gas in the high-temperature heat storage tank, and (ii) pass through a first heat exchanger, wherein the pressurized gas in the first conduit exchanges heat with the heat storage medium and / or the working fluid; and A thermodynamic cycle includes: a second heat exchanger configured to exchange heat between the working fluid and an external environment or a heat source / sink; a compressor / expander in fluid communication with the first heat exchanger and in fluid communication, directly or indirectly, with the second heat exchanger, configured to change the pressure of the working fluid between the first heat exchanger and the second heat exchanger; and One or more second pressure changing devices are located between the first heat exchanger and the second heat exchanger and are fluidly connected to the first heat exchanger and the second heat exchanger. They are configured to transfer the working fluid from the second heat exchanger to the first heat exchanger when the thermal energy storage and recovery system recovers energy, and to transfer the working fluid from the first heat exchanger to the second heat exchanger when the thermal energy storage and recovery system stores energy.

12. The thermal energy storage and recovery system according to claim 11, characterized in that The heat storage medium includes water.

13. The thermal energy storage and recovery system according to claim 11, characterized in that The second heat exchanger comprises a substantially isothermal heat exchanger.

14. The thermal energy storage and recovery system according to claim 11, characterized in that Also included is one or more first valves configured to open and close the first conduit.

15. The thermal energy storage and recovery system according to claim 14, characterized in that Also included is one or more vents or second valves on each of the low temperature heat storage tank and the high temperature heat storage tank, configured to reduce the pressure of the pressurized gas in the low temperature heat storage tank or the high temperature heat storage tank.

16. The thermal energy storage and recovery system according to claim 11, characterized in that When the thermal energy storage and recovery system recovers heat, the pressurized gas in the first conduit recovers a first heat from the heat storage medium and / or the working fluid, and the heat storage medium loses a second heat due to evaporation in the high-temperature heat storage tank, and the first heat at least offsets a portion of the second heat.

17. The thermal energy storage and recovery system according to claim 11, characterized in that The thermodynamic cycle includes a Brayton cycle, a Rankine cycle, a Stirling cycle or a trilateral cycle.

18. A method for recovering heat when discharging heat storage medium from a high-temperature heat storage tank, characterized in that: include: Adding pressurized gas into a high-temperature heat storage tank and a low-temperature heat storage tank respectively, wherein the low-temperature heat storage tank is in fluid communication with the high-temperature heat storage tank, the high-temperature heat storage tank stores a heat storage medium at a first temperature, and the low-temperature heat storage tank stores a heat storage medium at a second temperature lower than the first temperature; Discharging the heat storage medium from the high-temperature heat storage tank into the low-temperature heat storage tank; When discharging the heat storage medium, causing the heat storage medium to flow through one or more heat exchangers in fluid communication between the high temperature heat storage tank and the low temperature heat storage tank; and The pressurized gas is passed through a first conduit in fluid communication with the low-temperature heat storage tank and the high-temperature heat storage tank, wherein the first conduit passes through at least one of the one or more heat exchangers, so that the pressurized gas in the first conduit exchanges heat with the heat storage medium to recover at least part of the heat when the heat storage medium is discharged.

19. The method for recovering heat when discharging heat storage medium from a high-temperature heat storage tank according to claim 18, characterized in that: The discharging of the heat storage medium includes pumping the heat storage medium from the high-temperature heat storage tank to the low-temperature heat storage tank.

20. The method for recovering heat when discharging heat storage medium from a high temperature heat storage tank according to claim 18, characterized in that: It also includes removing heat from the thermal storage medium to a working fluid in a thermodynamic cycle located in one or more heat exchangers when discharging the thermal storage medium.

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