Carnot cell system

Abstract

The invention aims to provide the Carnot battery system and the operation method thereof, the system and the operation method adopt a CO2 hydrate cold storage mode, only CO2 and water are used as cold storage materials, the CO2 hydrate cold storage technology is latent heat cold storage, the phase change latent heat can reach 500kJ / kg and is far higher than that of water cold storage, and the Carnot battery system has the advantages of low material cost, low energy consumption and the like. The chemical safety and the stability are high. Through cooperative work of energy charging circulation, energy discharging circulation, the heat storage subsystem and the cold storage subsystem of the Carnot battery system, efficient energy storage and release are achieved, the admitting ability of a power grid to new energy is improved, peak clipping and valley filling are achieved, frequency modulation and voltage regulation are participated, and then the overall efficiency and economical efficiency of a power system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy storage and conversion, and in particular to a Carnot battery system. Background Art

[0002] In the current context of global climate change, countries have proposed carbon neutrality goals in response to the urgent need for energy transformation. The realization of this goal requires large-scale access to new energy sources such as wind power and photovoltaic power generation, but the unpredictability and seasonal fluctuations of these energy sources have brought huge challenges to the stable operation of the power grid. Therefore, achieving low cost, high efficiency, large capacity and environmental friendliness of energy storage technology has become the key to grid stability and high penetration of renewable energy.

[0003] Among existing energy storage technologies, Carnot Battery (CB) is based on the Carnot cycle principle and can convert electrical energy into heat and cold energy for storage on a large scale and for a long time, and then convert and generate electricity when electricity is needed, thereby effectively coping with the intermittent and instability of renewable energy, showing significant advantages. However, the cold storage density of common energy storage methods is relatively low, such as water cold storage (reference value is between 7 and 11.6 kWh / m3), so extremely high storage capacity is required to meet the actual application needs of high-performance energy storage, and storage capacity occupies a large space and resources. Therefore, it is urgent to develop efficient energy storage technologies with higher density, larger capacity and lower cost to meet the increasing demand for new energy access. Summary of the invention

[0004] In response to the above problems, the present application provides a Carnot battery system, which can reduce the energy storage cost of the Carnot battery and further improve the energy storage performance and overall operating efficiency of the Carnot battery system.

[0005] The present application provides a Carnot battery system, which includes four parts: a charging cycle, a discharging cycle, a heat storage subsystem, and a cold storage subsystem. The heat storage subsystem is used to store the heat energy released by the charging cycle, and transfer the heat energy to the discharging cycle 200 before discharging; the cold storage subsystem 400 is used to store the cold energy released by the charging cycle 100, and cool the circulating working fluid of the discharging cycle 200 after discharging. The charging cycle includes a CO2 hydrate generation pipe section, and CO2 gas and water generate CO2 hydrate in the CO2 hydrate generation pipe section and store it in the cold storage subsystem. CO2 hydrate cools the circulating working fluid of the discharging cycle in the cold storage subsystem. The Carnot battery system cycle adopts the cold storage method of CO2 hydrate, which can effectively reduce the energy storage cost.

[0006] According to the above technical solution, the Carnot battery system of the present application is composed of a charging cycle, a discharging cycle, a heat storage subsystem and a cold storage subsystem, and completes the cycle process of electric energy storage and conversion. In addition, the entire Carnot battery system cycle adopts the CO2 hydrate cold storage method, which effectively reduces the energy storage cost of the Carnot battery system.

[0007] In the optional technical solution, the CO2 gas and water in the CO2 hydrate generation pipe section efficiently achieve heat exchange and material state change through direct contact heat exchange.

[0008] According to this optional technical solution, direct contact heat exchange is adopted in the CO2 hydrate formation process. This heat exchange method avoids the thermal resistance problem caused by the existence of the heat exchange wall in the traditional indirect heat exchange method in principle, making the heat transfer between CO2 and water more direct and efficient.

[0009] In an optional technical solution, a spiral bond is installed in the CO2 hydrate generation pipe section, which can significantly increase the contact area of ​​the reactants during the hydrate generation process and help remove the reaction heat, creating more favorable conditions for the generation of CO2 hydrate.

[0010] According to this optional technical solution, the present application installs a spiral bond in the CO2 hydrate generation pipe section to promote the spiral flow of the fluid. On the one hand, it enhances the mixing degree between the gas and the liquid. On the other hand, the spiral flow helps to remove the heat generated during the hydrate generation process in time, maintain the continuous progress of the reaction, and effectively enhance the CO2 hydrate generation process.

[0011] In an optional technical solution, the Carnot battery system also includes a bubbling mechanism connected to the CO2 hydrate generation pipe section, which bubbles into the CO2 hydrate generation pipe section to increase the contact area between gas and liquid and enhance the generation of CO2 hydrate.

[0012] According to this optional technical solution, the present application sets a bubbling mechanism in front of the CO2 hydrate generation pipe section, which greatly increases the contact area between CO2 and water by allowing the CO2 gas to form bubbles in the water, thereby improving the generation amount and generation rate of CO2 hydrate.

[0013] In an optional technical solution, the charging cycle includes a first compressor, a cooler, a throttle valve, a CO2 hydrate generation pipe section and a first filter which are connected in sequence, wherein the cooler constitutes a coupling node between the heat storage subsystem and the charging cycle, and the CO2 hydrate generation pipe section and the first filter constitute coupling nodes between the charging cycle and the cold storage subsystem.

[0014] In an optional technical solution, the energy release cycle includes a heater, a turbine, a condenser and a pump connected in sequence, wherein the condenser constitutes a coupling node between the energy release cycle and the cold storage subsystem, and the heater constitutes a coupling node between the energy release cycle and the heat storage subsystem.

[0015] In an optional technical solution, the heat storage subsystem includes a cooler, a heat storage medium cold tank, a heater, and a heat storage medium hot tank connected in sequence, wherein the cooler constitutes a coupling node between the heat storage subsystem and the energy charging cycle, and the heater constitutes a coupling node between the energy discharging cycle and the heat storage subsystem.

[0016] In an optional technical solution, the cold storage subsystem includes a water storage tank, a water pump, a CO2 hydrate generation pipe section, a first filter, a CO2 hydrate slurry storage tank and a condenser which are connected in sequence, wherein the CO2 hydrate generation pipe section and the first filter constitute a coupling node between the energy charging cycle and the cold storage subsystem, and the condenser constitutes a coupling node between the energy discharging cycle and the cold storage subsystem.

[0017] In an optional technical solution, the cold storage subsystem also includes a second filter and a second compressor, wherein the condenser, the second filter and the second compressor are connected in sequence to form a cycle.

[0018] In the optional technical solution, the pressure range of the CO2 hydrate generation pipe section is 3 to 4 MPa, and the temperature range is 4 to 10°C, maintaining a suitable environment for CO2 hydrate formation.

[0019] According to this optional technical solution, the temperature and pressure of the CO2 hydrate generation pipe section are controlled within this range, so that the CO2 molecules can be more effectively dissolved in water and tightly combined with water molecules to form hydrates, providing a good environment for the nucleation and growth of hydrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of a Carnot battery system according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of the structure of the CO2 hydrate generation pipe section in the system of the embodiment of the present invention.

[0022] Description of Reference Numerals

[0023] 100-charging cycle; 200-discharging cycle; 300-heat storage subsystem; 400-cold storage subsystem;

[0024] 1-first compressor; 2-cooler; 3-throttle valve; 4-CO2 hydrate generation pipe section; 5-first filter; 6-turbine; 7-condenser; 8-pump; 9-heater; 10-heat storage medium cold tank; 11-heat storage medium hot tank; 12-CO2 hydrate slurry storage tank; 13-water storage tank; 14-water pump; 15-second filter; 16-second compressor. DETAILED DESCRIPTION

[0025] It should be noted that the working principle, characteristics and advantages of the Carnot battery system according to the present application will be explained below in an illustrative manner, but it should be understood that all descriptions are given for illustrative purposes only and should not be construed as forming any limitation on the present application.

[0026] The present invention will be further described below in conjunction with specific implementations and accompanying drawings.

[0027] <First Embodiment>

[0028] like Figure 1 The structural schematic diagram of the Carnot battery system shown in FIG. 1 includes four parts: a charging cycle 100, a discharging cycle 200, a heat storage subsystem 300, and a cold storage subsystem 400. The heat storage subsystem 300 is used to store the heat energy released by the charging cycle 100 and transfer the heat energy to the discharging cycle 200 before discharging; the cold storage subsystem 400 is used to store the cold energy released by the charging cycle 100 and cool the circulating working fluid of the discharging cycle 200 after discharging.

[0029] The Carnot battery system converts electrical energy into heat and cold energy for storage during charging, and releases the heat and cold energy stored in the cycle to generate electricity during discharge, thereby achieving efficient conversion and release of electrical energy. Specifically, when the Carnot battery system stores and converts electrical energy, the circulating medium (CO2 is used as an example here) circulates in the charging cycle 100, the discharging cycle 200, the heat storage subsystem 300, and the cold storage subsystem 400, achieving efficient storage and conversion of energy. During the charging process, work is first done on the circulating working fluid CO2, and the CO2 gas is compressed into a high-temperature and high-pressure supercritical fluid in the charging cycle 100. During the compression process, the temperature and pressure of the CO2 gas are increased and the thermal energy of CO2 is significantly increased. Subsequently, the high-temperature and high-pressure CO2 supercritical fluid exchanges heat with the heat storage medium (such as high-pressure water, molten salt, etc.) in the heat storage subsystem 300. Since the temperature of the heat storage medium is relatively low, the heat of the CO2 supercritical fluid is spontaneously transferred to the heat storage medium. At the same time, the thermal energy of the CO2 supercritical fluid itself gradually decreases. When it reaches below a certain critical temperature and pressure, the CO2 supercritical fluid begins to undergo a phase change and transforms into gaseous CO2. This phase change process is an exothermic reaction, and the released reaction heat is absorbed and stored by the heat storage medium in the heat storage subsystem 300 for use in subsequent discharge processes. Subsequently, the gaseous CO2 expands after the phase change to reduce the pressure and further lower its temperature. Under certain conditions, the CO2 molecules react with water molecules to generate CO2 hydrates which are stored in the cold storage subsystem 400, thereby realizing the storage of cold energy of the cold storage subsystem 400 in the charging cycle 100. During the discharge process, the high-pressure CO2 absorbs heat energy from the heat storage subsystem 300 and its temperature rises. When the temperature rises to a level that can do work and drive the generator to generate electricity, the high-temperature and high-pressure CO2 in the energy discharge cycle 200 drives the generator to generate electricity. During the discharge process, the pressure of the CO2 gas itself decreases and the temperature drops. The CO2 gas that has completed energy release is then transported to the cold storage subsystem 400. The CO2 hydrate slurry stored in the cold storage subsystem 400 is cooled and its temperature is further reduced. The cooled CO2 gas is filtered and compressed again into a high-pressure circulating working fluid, and enters the energy discharge cycle 200 to prepare for the next round of energy release cycle. The charging cycle 100 and the energy discharge cycle 200 are coordinated by the heat storage subsystem 300 and the cold storage subsystem 400, and the Carnot battery system completes the cycle process of electrical energy storage and conversion.

[0030] In this embodiment, a CO2 hydrate generation pipe section 4 is provided in the charging cycle 100. The CO2 gas released in the charging cycle 100 generates CO2 hydrate in the CO2 hydrate generation pipe section 4 with water from the cold storage subsystem 400. Then the CO2 hydrate is transported and stored in the cold storage subsystem 400 to provide cooling for the high-temperature CO2 after the energy is released in the energy discharge cycle 200. Specifically, when the CO2 supercritical fluid in the charging cycle 100 exchanges heat with the heat storage medium in the heat storage subsystem 300, the CO2 supercritical fluid's own thermal energy is reduced and a phase change occurs to transform into gaseous CO2. The released CO2 gas enters the CO2 hydrate generation pipe section 4 after depressurization, and reacts with water from the cold storage subsystem 400 in the CO2 hydrate generation pipe section 4 in the charging cycle 100. Under certain temperature and pressure conditions, CO2 gas molecules and water molecules contact and collide with each other. In this process, CO2 gas molecules gradually dissolve in water. When the CO2 dissolved in water reaches a certain concentration, CO2 molecules and water molecules are tightly combined through hydrogen bonds and other interaction forces to form a stable lattice structure and finally generate CO2 hydrates. The CO2 hydrate generated in the CO2 hydrate generation pipe section 4 is transported as cold energy reserve and stored in the cold storage subsystem 400. In the energy release cycle 200, after completing the discharge, the high-temperature and high-pressure CO2 enters the coupling point of the energy release cycle 200 and the cold storage subsystem 400 to contact and exchange heat with the CO2 hydrate. Due to the temperature difference between the two, the heat is transferred from the high-temperature CO2 to the low-temperature CO2 hydrate. As the CO2 hydrate continuously absorbs the heat of the high-temperature CO2, its internal chemical bonds break due to the absorption of energy, and the crystal structure of the CO2 hydrate is destroyed and a dissociation reaction occurs to generate water and CO2 gas. Since the dissociation reaction is an endothermic process, the CO2 hydrate exchanges heat with the high-temperature and high-pressure circulating working fluid CO2 during the dissociation reaction. The circulating working fluid CO2 in the energy release cycle 200 has its own temperature reduced due to the absorbed heat, thereby achieving the purpose of cooling the circulating working fluid CO2 in the energy release cycle 200 during the dissociation process.

[0031] It should be noted that, although the circulating working fluid of the Carnot battery system for energy storage and conversion is CO2 as an example in the embodiments of this application, it is not limited to this. Any medium that can meet the requirements of effective heat transfer and material change, including but not limited to certain inert gases, other low-boiling hydrocarbons or their mixed working fluids, and new working fluids with similar thermophysical properties and chemical stability, as long as they can achieve the technical effects of this application, belongs to the protection scope of this application. This description also applies to other embodiments of this application.

[0032] In addition, the heat storage medium in the heat storage subsystem 300 mentioned in the embodiment of the present application includes but is not limited to common sensible heat storage working fluids such as high-pressure water and molten salt, latent heat storage working fluids such as paraffin, salts (such as sodium nitrate, sodium acetate), organic compounds, and thermochemical heat storage working fluids, etc. Any material with suitable specific heat capacity, good thermal conductivity and effective heat storage can be used as the heat storage medium of the embodiment of the present application, and all belong to the protection scope of the present application. This description also applies to other embodiments of the present application.

[0033] As a preferred embodiment of the present application, the CO2 hydrate formation pressure range is 3 to 4 MPa, and the temperature range is 4 to 10°C. Within this pressure and temperature range, the interaction between CO2 molecules and water molecules can reach a relatively ideal state, so that CO2 molecules can be more effectively dissolved in water and tightly combined with water molecules to form hydrates, providing a good environment for the nucleation and growth of hydrates, thereby improving the generation efficiency of CO2 hydrates.

[0034] It should be noted that although the pressure range and temperature range mentioned in the embodiments of the present application are only preferred embodiments, any combination of pressure and temperature ranges that can achieve the technical effect of allowing CO2 molecules to interact and combine with water molecules to form CO2 hydrates falls within the protection scope of the present application.

[0035] As a preferred embodiment of the present application, in the CO2 hydrate pipe section 4, CO2 gas and water generate CO2 hydrate through direct contact heat exchange. In this process, the reaction of CO2 gas and water to generate CO2 hydrate is an exothermic reaction. The heat released by the reaction is transferred in the gas-liquid system. After the CO2 liquid in the CO2 hydrate generation pipe section 4 absorbs the reaction heat, the intermolecular binding force is overcome, thereby causing a phase change from liquid to gas. Since there is no thermal resistance influence of the heat exchange medium between the two substances, the whole process efficiently realizes heat exchange and material state change, which promotes energy conversion and transfer in the Carnot battery system.

[0036] In the charging cycle 100 of the Carnot battery system, the first compressor 1, the cooler 2, the throttle valve 3, the CO2 hydrate generation pipe section 4 and the first filter 5 are connected in sequence, wherein the cooler 2 constitutes a coupling node between the heat storage subsystem 300 and the charging cycle 100, and the CO2 hydrate generation pipe section 4 and the first filter 5 constitute a coupling node between the charging cycle 100 and the cold storage subsystem 400.

[0037] Specifically, the CO2 gas first passes through the first compressor 1, which compresses the CO2 gas into a high-temperature supercritical fluid containing a large amount of internal energy to prepare for the subsequent energy release. The high-temperature supercritical CO2 fluid is then transported to the cooler 2 at the coupling node between the heat storage subsystem 300 and the charging cycle 100. Since the temperature of the circulating medium inside the cooler 2 is lower than the temperature of the supercritical CO2 fluid, heat is spontaneously transferred from the high-temperature supercritical CO2 fluid to the circulating medium inside the cooler 2. In this process, the supercritical CO2 fluid undergoes a phase change and gradually turns back to gaseous CO2, and releases heat energy into the heat storage subsystem 300. The heat storage medium (such as high-pressure water, molten salt, etc.) in the heat storage subsystem 300 increases its own temperature after absorbing the heat released by the CO2 supercritical fluid, realizing the effective storage of thermal energy, and preparing for the high-pressure CO2 in the subsequent energy release cycle 200 to absorb heat energy in the heat absorber to expand and generate power. After the phase change, the gaseous CO2 expands through the throttle valve 3 and enters the CO2 hydrate generation pipe section 4. When the CO2 gas passes through the throttle valve 3, the pressure drops rapidly due to the throttling effect, causing the CO2 gas to expand in preparation for entering the CO2 hydrate generation pipe section 4. In the CO2 hydrate generation pipeline 4, the CO2 gas and the water transported from the cold storage subsystem 400 generate CO2 hydrates under certain environmental conditions, wherein the process of CO2 gas and water molecules generating CO2 hydrates is an exothermic reaction. After absorbing the reaction heat, the CO2 liquid in the CO2 hydrate generation pipe section 4 increases its internal energy and overcomes the binding force between molecules, thereby changing from CO2 liquid to CO2 gas, and flows out from the outlet of the CO2 hydrate generation pipe section 4 and enters the first filter 5. The first filter 5 distinguishes the CO2 gas and CO2 hydrate slurry generated in the CO2 hydrate generation pipeline 4, wherein the CO2 gas enters the first compressor 1 again and prepares for a new charging cycle 100, while the CO2 hydrate slurry is transported and stored into the cold storage subsystem 400 to provide cold energy for the high-temperature circulating working fluid CO2 after energy release in the subsequent energy release cycle 200, thereby completing the energy conversion and storage during the entire charging cycle.

[0038] As a preferred embodiment of the present application, the charging cycle 100 is a transcritical CO2 heat pump cycle, and the outlet pressure of CO2 from the first compressor 1 exceeds its critical pressure (7.38MPa). Specifically, after the CO2 gas enters the first compressor 1, the first compressor 1 performs work on it so that the CO2 gas is compressed into a high-temperature supercritical fluid containing a large amount of internal energy, creating conditions for subsequent energy release. Since the outlet pressure of the first compressor 1 exceeds the critical pressure of CO2 (7.38MPa), the pressure of CO2 at the outlet of the first compressor 1 exceeds its critical pressure (7.38MPa). This precise pressure control ensures that CO2 can be stably in a supercritical state, avoiding the problem of unstable phase of CO2 due to insufficient or fluctuating pressure, and ensuring the continuity and reliability of the Carnot battery system in the energy conversion process.

[0039] In the energy release cycle 200 , the heater 9 , the turbine 6 , the condenser 7 and the pump 8 are connected in sequence, wherein the condenser 7 constitutes a coupling node between the energy release cycle 200 and the cold storage subsystem 400 , and the heater 9 constitutes a coupling node between the energy release cycle 200 and the heat storage subsystem 300 .

[0040] Specifically, when the liquid CO2 enters the pump chamber of the pump 8, it is subjected to the combined effects of various forces such as centrifugal force and friction force. Under the pressure accumulation effect brought about by the pump body structure design, the distance between the molecules of the liquid CO2 is compressed and the internal energy continues to increase. When the liquid CO2 flows out from the outlet of the pump 8, the pressure is significantly increased and converted into high-pressure CO2. When the high-pressure CO2 passes through the heater 9 at the coupling node of the energy release cycle 200 and the heat storage subsystem 300, the high-pressure CO2 continuously absorbs the heat energy transferred from the CO2 supercritical fluid to the heat storage medium (such as high-pressure water, molten salt, etc.) in the heat storage subsystem 300. As the temperature of the high-pressure CO2 rises to the specified temperature and has sufficient energy for subsequent expansion and work, the high-temperature and high-pressure CO2 enters the CO2 turbine 6 to expand, do work and generate electricity. Since the high-temperature and high-pressure CO2 has higher energy, when passing through the blade channel of the turbine 6, the rotating shaft of the turbine 6 is connected to the generator, and the volume of the high-temperature and high-pressure CO2 gas expands and drives the blades of the turbine 6 to rotate, thereby driving the generator to generate electricity, realizing the process of converting thermal energy into mechanical energy and then into electrical energy. After expansion and work, the CO2 working medium becomes a low-pressure state and enters the condenser 7, a coupling node between the energy release cycle 200 and the cold storage subsystem 400. In the condenser 7, the expanded high-temperature CO2 working medium transfers heat with the low-temperature CO2 hydrate slurry stored in the cold storage subsystem 400. During this process, when the high-temperature CO2 working medium contacts the CO2 hydrate slurry with a lower temperature, the high-temperature CO2 working medium continuously releases heat to the low-temperature CO2 hydrate slurry. During this process, the internal energy of the high-temperature CO2 molecules gradually decreases and the temperature continues to drop. Finally, the high-temperature CO2 achieves the effect of being cooled and is cooled to liquid CO2. While absorbing heat, the CO2 hydrate slurry triggers its own dissociation reaction, which destroys the originally stable CO2 hydrate structure and regenerates water and CO2 gas. The CO2 cooled to a liquid state by the CO2 hydrate slurry enters the pump 8 and is compressed into a high-pressure state and enters a new energy release cycle 200 again.

[0041] As a preferred embodiment of the present application, the energy release cycle 200 is a Rankine cycle, wherein the energy release cycle 200 covers two different types of Rankine cycles, namely, a transcritical Rankine cycle and a subcritical Rankine cycle. In a transcritical Rankine cycle, the pressure on the high-pressure side of CO2 is higher than the critical pressure. Under this high-pressure condition, the density of CO2 increases and its physical properties are closer to liquid properties, while the interaction between molecules is enhanced. In a subcritical Rankine cycle, the pressure of CO2 throughout the process is less than its critical pressure, and its physical and chemical properties are relatively stable. Specifically, in the energy release cycle 200, CO2 is converted into high-pressure CO2 when it flows out from the outlet of the pump 8, and its pressure throughout the process is greater than the critical pressure (7.38MPa). The CO2 on the high-pressure side can efficiently absorb the heat from the CO2 heater 9 in the heat storage subsystem 300, and reserve energy for subsequent expansion work. When the high-pressure CO2 has sufficient energy, it enters the CO2 turbine 6, and its pressure throughout the process is less than the critical pressure (7.38MPa). Since the high-temperature and high-pressure CO2 has higher energy, and on the low-pressure side, the pressure of CO2 is lower than the critical pressure, this significant pressure difference between the high and low pressure sides forms a strong driving force, causing the CO2 to expand violently when flowing through the turbine device. During the expansion process, the internal energy of CO2 is rapidly converted into mechanical energy, which drives the turbine blades to rotate and then drives the generator to generate electricity, realizing efficient conversion from thermal energy to mechanical energy and then to electrical energy.

[0042] In the heat storage subsystem 300, the cooler 2, the heat storage medium cold tank 10, the heater 9, and the heat storage medium hot tank 11 are connected in sequence to form a complete heat storage and heat transfer loop. Specifically, the heat storage medium (such as high-pressure water, molten salt, etc.) enters the heat storage medium cold tank 10 during the charging process 100, flows out of the heat storage medium cold tank 10 under the action of a specific driving mechanism (such as the pressure difference generated by the pump drive), and is transported to the CO2 cooler 2, the coupling point of the heat storage subsystem 300 and the charging cycle 100. In the CO2 cooler 2, the heat storage medium exchanges heat with the high-temperature supercritical CO2 fluid. Since the temperature of the high-temperature supercritical CO2 fluid is higher than that of the heat storage medium, the heat is spontaneously transferred from the high-temperature supercritical CO2 fluid to the heat storage medium. In this process, the heat storage medium increases its temperature macroscopically due to the increase in molecular internal energy due to the absorption of heat. After completing the heat absorption, the heat storage medium is transported to the heat storage medium hot tank 11 under the action of the system pressure difference or other transport power. The heat storage medium hot tank 11 has an efficient insulation structure, which can minimize heat loss and ensure that the stored heat energy is effectively preserved. When the system enters the energy release stage and there is a heating demand, the heat storage medium is transported from the heat storage medium hot tank 11 to the CO2 heater 9, the coupling point between the heat storage subsystem 300 and the energy release cycle 200, under the corresponding control mechanism. In the CO2 heater 9, the heat storage medium exchanges heat with the high-pressure CO2 in the energy release cycle 200. During this process, the heat storage medium transfers its stored heat energy to the high-pressure CO2 to increase its internal energy, providing sufficient energy for the subsequent expansion and work process of the high-pressure CO2. After completing the heating of the high-pressure CO2, the temperature of the heat storage medium decreases after releasing part of the heat. Under the guidance of the system, the heat storage medium after the heat is released is transported back to the heat storage medium cold tank 10 for storage, so as to be recycled for the next energy charging process, thereby realizing the circulation of the heat storage subsystem 300 in the energy storage and release process of the entire system, and ensuring the stable operation of the Carnot battery system and the efficient use of energy.

[0043] It should be noted that the heat storage medium in this embodiment is not limited to high-pressure water and molten salt. As long as it can absorb CO2 heat from the heat storage medium cold tank 10 and release heat to the high-pressure CO2 in the energy release cycle 200 during the energy release process, it has suitable thermophysical properties such as specific heat capacity, thermal conductivity, phase change temperature, and stable chemical properties. It will not react adversely with other substances in the system during the charging and discharging cycles. Any substance that can realize the energy storage and release functions of this application, including but not limited to certain organic phase change materials, new composite heat storage materials, etc., belongs to the protection scope of this application.

[0044] In addition, although the embodiment of the present application mentions a specific driving mechanism (such as the pressure difference generated by the pump drive) to prompt the heat storage medium to flow out of the heat storage medium cold tank 10 and be transported to the CO2 cooler 2, it is not limited to this. Any driving method that can provide sufficient power for the heat storage medium to overcome resistance and achieve a stable flow from the heat storage medium cold tank 10 to the CO2 cooler 2, including but not limited to the use of gravitational potential energy difference, electromagnetic force drive, pressure difference generated by other mechanical transmissions, etc., can achieve the technical effects of the present application and belong to the protection scope of the present application.

[0045] In the cold storage subsystem 400, a CO2 hydrate slurry storage tank 12, a CO2 condenser 7, a water storage tank 13, a water pump 14, a CO2 hydrate generation pipe section 4 and a first filter 5 are included. Among them, the water storage tank 13, the water pump 14, the CO2 hydrate generation pipe section 4, the first filter 5, the CO2 hydrate slurry storage tank 12 and the condenser 7 are sequentially connected, the CO2 hydrate generation pipe section 4 and the first filter 5 constitute the coupling node of the charging cycle 100 and the cold storage subsystem 400, and the condenser 7 constitutes the coupling node of the discharging cycle 200 and the cold storage subsystem 400.

[0046] Specifically, during the charging process, the water storage tank 13 is used as a container for storing water, and the water inside it is at a specific temperature, pressure and chemically stable state. The rotation of the impeller inside the water pump 14 under the drive of the system generates a pressure difference, so that the water in the water storage tank 13 overcomes factors such as pipeline resistance and gravity, and is transported into the CO2 hydrate generation pipe section 4 at a certain flow rate. In the CO2 hydrate generation pipe section 4, the water from the water pump 14 and the CO2 from the charging cycle 100 collide and interact with each other under the specific temperature, pressure and physical and chemical environment in the CO2 hydrate generation pipe section 4. The water molecules combine with the CO2 molecules through chemical bonding such as hydrogen bonds to finally form CO2 hydrates. The generated CO2 hydrate flows out from the outlet of the CO2 hydrate generation pipe section 4 and enters the first filter 5. The first filter 5 separates the CO2 gas and the CO2 hydrate slurry according to its filtering structure and material properties. The separated CO2 hydrate slurry enters the CO2 hydrate slurry storage tank 12 with good sealing and thermal insulation properties for storage under the action of gravity, pressure difference or other conveying mechanisms, ensuring that the stored CO2 hydrate slurry maintains stable physical and chemical properties during storage, preparing for the cold energy supply in the subsequent energy release cycle 200.

[0047] The cold storage subsystem 400 also includes a second filter 15 and a second compressor 16, wherein the condenser, the second filter 15 and the second compressor 16 are connected in sequence to form a closed and continuous circulation system. Specifically, during the energy release process, the CO2 hydrate slurry enters the CO2 condenser 7 from the CO2 hydrate slurry storage tank 12 for heat exchange. The CO2 condenser 7 has a special heat exchange structure and a highly efficient heat conduction material. When the CO2 hydrate slurry enters the CO2 condenser 7, it undergoes heat transfer with the high-temperature CO2 working medium after the CO2 turbine 6 expands and generates power in the energy release cycle 200. Since the temperature of the CO2 hydrate slurry is relatively low, while the temperature of the CO2 working medium in the energy release cycle 200 is relatively high, heat is transferred from the high-temperature CO2 working medium to the low-temperature CO2 hydrate slurry. During the heat transfer process, the internal energy of the CO2 working medium in the energy release cycle 200 gradually decreases, the intensity of the molecular motion decreases accordingly, and its temperature continues to decrease, and finally the high-temperature phase CO2 in the gaseous state is cooled to the liquid CO2. At the same time, the CO2 hydrate slurry undergoes chemical changes in the process of absorbing heat. After the CO2 hydrate is heated, its internal chemical bonds are broken under the action of thermal energy, and a dissociation reaction occurs to generate water and CO2 gas. The dissociation products of water and CO2 gas flow out of the outlet of the condenser 7. At the outlet of the condenser 7, a second filter 15 is provided. The second filter 15 separates the dissociation products of water and CO2 gas based on the difference in the physical and chemical properties of the substances. The separated CO2 gas is pressurized by the second compressor 16. In this process, the distance between CO2 gas molecules decreases and the pressure increases. The pressurized CO2 gas re-enters the inlet of the condenser 7 of the energy release cycle 200 along the pipeline. The water separated from the second filter 15 is transported to the water storage tank 13 for storage under the action of a corresponding transport mechanism (such as gravity, pressure difference or a specially designed water pipeline) to be prepared for subsequent participation in the CO2 hydrate formation reaction of the CO2 hydrate formation pipeline in the energy charging cycle 100, thereby realizing energy conversion and material recycling of the entire cold storage subsystem 400 during the energy release and charging process.

[0048] It should be noted that, although the embodiment of the present application mentions that the water is transported to the water storage tank 13 for storage under the action of a corresponding transport mechanism (such as gravity, pressure difference or a specially designed water pipeline) after separation by the second filter 15, it is not limited to this. Any transport method that can transfer water from the second filter 15 to the water storage tank 13, including but not limited to mechanical suction, fluid convection effect, magnetically driven fluid flow, or a new transport method formed by a combination of multiple methods, can achieve the technical effect of the present application as long as it can achieve stable and efficient transport of water from the separation position to the water storage tank 13, and all belong to the protection scope of the present application.

[0049] <Second Embodiment>

[0050] The Carnot battery system provided in the second embodiment of the present application and the Carnot battery system in the above-mentioned embodiment of the present application are described using the same names or symbols, and they all belong to the same content, which will not be repeated here.

[0051] Figure 2 It is a structural schematic diagram of the CO2 hydrate generation pipe segment 4 in the embodiment of the present application. In order to improve the CO2 hydrate generation effect, a spiral bond is provided in the CO2 hydrate pipe segment 4. Specifically, in the process of CO2 generation in the CO2 hydrate pipe segment 4, due to the unique geometric shape of the spiral bond and the arrangement of the spiral bond in the pipe segment, when the CO2 gas released by the CO2 cooler 2 and the water from the cold storage subsystem 400 form a mixed fluid and flow through the CO2 hydrate generation pipe segment 4 in the energy charging cycle 100, the spiral bond provided in the CO2 hydrate pipe segment 4 can induce the mixed fluid to form a spiral flow in the pipe segment. Specifically, under the action of the spiral flow, the CO2 gas molecules and the water molecules realize non-linear flow under the spiral trajectory, which enables the CO2 gas molecules and the water molecules to be fully mixed and contacted during the hydrate generation process, which significantly increases the contact area between the gas and the liquid, and increases the probability of collision and contact between the CO2 gas molecules and the water molecules. In addition, the spiral flow also helps to remove the heat generated during the hydrate formation process, prompting the generated heat to diffuse and transfer in a timely manner with the spiral flow of the fluid, thereby effectively maintaining the thermal equilibrium environment required for the CO2 hydrate formation reaction, promoting the continuous progress of the CO2 hydrate formation reaction, and creating more favorable conditions for the reaction between CO2 and water.

[0052] <Third Embodiment>

[0053] The Carnot battery system provided in the third embodiment of the present application and the Carnot battery system in the above embodiments of the present application are described using the same names or symbols, and they all belong to the same content, which will not be repeated here.

[0054] The CO2 hydrate generation pipe section 4 also includes a bubbling mechanism, which is located before the CO2 hydrate generation pipe section 4 in the layout of the entire system, and is interconnected with the CO2 hydrate generation pipe section 4 to form an organic whole. As a preferred embodiment of the present application, the bubbling mechanism is a throttle valve 3. When CO2 flows through the throttle valve 3, the special structural design and flow channel geometry inside the throttle valve 3 trigger the throttling expansion of CO2. In this process, when CO2 passes through the narrow throttle port, its flow rate increases sharply and is accompanied by a decrease in pressure and a sharp change in temperature. Under the action of throttling expansion, CO2 breaks its stable single-phase state and transforms into a two-phase fluid, that is, it contains both CO2 gas and CO2 liquid phases. The CO2 gas portion enters the CO2 hydrate generation pipe section 4 connected to the throttle valve 3 under the synergistic effect of pressure difference and fluid flow characteristics, and forms a large number of bubbles in the water flow of the CO2 hydrate generation pipe section 4. The bubble surface area is large, thereby increasing the effective contact area between the gas and the liquid, allowing more CO2 molecules and water molecules to contact and collide with each other, thereby effectively enhancing the formation of CO2 hydrates, and improving the energy conversion and storage efficiency of the entire Carnot battery system during the charging cycle.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Carnot battery system, characterized in that: The Carnot battery system includes a charging cycle, a discharging cycle, a heat storage subsystem and a cold storage subsystem. The charging cycle includes a CO2 hydrate generation pipe section. CO2 gas and water generate CO2 hydrate in the CO2 hydrate generation pipe section and store it in the cold storage subsystem. The CO2 hydrate cools the circulating working fluid of the discharging cycle in the cold storage subsystem.

2. The Carnot battery system according to claim 1, characterized in that: The CO2 gas and the water in the CO2 hydrate generation pipe section exchange heat through direct contact.

3. The Carnot battery system according to claim 2, characterized in that: A spiral tie is installed in the CO2 hydrate generation pipe section.

4. The Carnot battery system according to claim 3, characterized in that: It also includes a bubbling mechanism, which is connected to the CO2 hydrate generation pipe section and bubbles into the CO2 hydrate generation pipe section.

5. The Carnot battery system according to claim 1, characterized in that: The charging cycle includes a first compressor, a cooler, a throttle valve, a CO2 hydrate generation pipe section and a first filter which are connected in sequence. The cooler constitutes a coupling node between the heat storage subsystem and the charging cycle, and the CO2 hydrate generation pipe section and the first filter constitute a coupling node between the charging cycle and the cold storage subsystem.

6. The Carnot battery system according to claim 1, characterized in that: The energy discharging cycle comprises a heater, a turbine, a condenser and a pump which are connected in sequence. The condenser constitutes a coupling node between the energy discharging cycle and the cold storage subsystem, and the heater constitutes a coupling node between the energy discharging cycle and the heat storage subsystem.

7. The Carnot battery system according to claim 1, characterized in that: The heat storage subsystem includes a cooler, a heat storage medium cold tank, a heater, and a heat storage medium hot tank connected in sequence. The cooler constitutes a coupling node between the heat storage subsystem and the energy charging cycle, and the heater constitutes a coupling node between the energy discharging cycle and the heat storage subsystem.

8. The Carnot battery system according to claim 1, characterized in that: The cold storage subsystem includes a water storage tank, a water pump, a CO2 hydrate generation pipe section, a first filter, a CO2 hydrate slurry storage tank and a condenser which are connected in sequence. The CO2 hydrate generation pipe section and the first filter constitute a coupling node between the energy charging cycle and the cold storage subsystem, and the condenser constitutes a coupling node between the energy discharging cycle and the cold storage subsystem.

9. The Carnot battery system according to claim 8, characterized in that: The cold storage subsystem further includes a second filter and a second compressor, and the condenser, the second filter and the second compressor are connected in sequence to form a cycle.

10. The Carnot battery system according to claim 1, characterized in that: The pressure range of the CO2 hydrate generation pipe section is 3-4 MPa, and the temperature range is 4-10°C.

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