CO2 energy storage and air-conditioning integrated circulating system and method based on constant-volume hot-pressing method

Abstract

The invention discloses a CO2 energy storage and air conditioner integrated circulating system and method adopting an isovolumetric hot-pressing method, and the system comprises an 8MPa spherical tank, an 80MPa high-pressure vertical pipe type variable-temperature variable-pressure energy storage tank, a built-in heat exchanger of the 8MPa spherical tank, a built-in heat exchanger of the 80MPa high-pressure vertical pipe type variable-temperature variable-pressure energy storage tank, a CO2 compressor, an expansion machine, an ejector and the like which are connected through a pipe network controlled by an automatic valve, and the operation modes Under the atmospheric condition of-40-40 DEG C, heat absorbed from the environment and compression heat in the heating or refrigerating process can be transmitted to closed liquid CO2 in the energy storage tank, so that the closed liquid CO2 absorbs heat in an isometric manner, the temperature and the pressure are increased to a high enthalpy value of 60-70 MPa / 200-250 DEG C and the energy storage density of 850 kJ. Kg <-1 >, in the energy release process, the enthalpy is converted into power to be output through an expansion machine, and the ratio of the power to the energy storage consumption power is not lower than 0.70; the energy storage volume density is larger than 6.0 kWh.m <-3 >, and particularly, the refrigeration / heating performance coefficient of a coupled and received air conditioner is equivalent to that of an existing air conditioner.

Description

Technical Field

[0001] The present invention relates to the technical fields of energy storage and air conditioning, in particular to the coupling of energy storage and air conditioning thermal processes and the method and system integration for efficiently converting low-grade thermal energy into mechanical energy. Background Art

[0002] Energy storage and air conditioning belong to the two major fields of energy supply and use respectively, but they have commonalities in terms of the conversion nature of thermal energy and power (thermal - dynamic). Existing compressed air and compressed CO2 energy storage technologies have a charge / discharge cycle efficiency of 0.65 - 0.8 (Zheng Pingyang, Yue Yunkai, etc. Research progress of liquid carbon dioxide energy storage system based on different liquefaction methods. Southern Energy Construction, 2024, 11(2). https: / / doi.org / 10.16516 / j.gedi.issn2095-8676.2024.02.005 , 2023 - 09 - 18), with a process loss of 20 - 35% of electric energy; existing refrigeration / heating air conditioning technologies have a coefficient of performance (COP) of 2.5 - 4.0, that is, the electric energy consumed to drive the cold / heat exchange between the environment and users is 25% - 40% of the refrigeration / heating load. And the lost or consumed electric energy ultimately becomes low-grade thermal energy discharged to the environment. Constructing an efficient conversion cycle system for low-grade thermal energy and power is an important way to improve energy utilization efficiency and achieve low-carbon energy conservation in the above technical fields.

[0003] Therefore, the present invention constructs an isochoric heat-pressurized CO2 energy storage and air conditioning integrated cycle system and method. The technical idea is: in the energy storage stage, the thermal energy input from the environment and generated by compression is collected and directly converted into the high-level enthalpy of a high-density energy storage medium through the isochoric heat-pressurization method of CO2. In the energy release stage, the high-level enthalpy is converted into power output, and the energy storage / energy release process simultaneously completes air conditioning refrigeration / heating. Taking CO2 as the medium, the three energy conversion paths of cold / heat / motion between (-40 - 220)°C are ingeniously integrated, and compared with the existing separate energy storage or separate air conditioning technologies, it has a gain in converting environmental low-grade energy into available energy.

[0004] The cycle system for realizing the present invention includes: a spherical tank (20) with a pressure not exceeding 8 MPa and several 80 MPa high-pressure vertical variable-temperature and variable-pressure storage tanks (10). Each storage tank and its built-in two-pass tubular external fin heat exchanger (11) are connected to equipment such as a transcritical CO2 compressor, expander, ejector, CO2 evaporator, and air conditioning supply air heater through a pipe network controlled by automatic valves and can be switched in various combination modes, as described later. The energy release medium outlet of the storage tank 10 and the inlet and outlet of the heat exchange fluid of the built-in fin heat exchanger 11 are arranged in the top header of the storage tank (the ratio of the effective heat transfer area of the fins to the volume of the storage tank ≥ 180 m 2 / m 3 , and the ratio to the inner surface area of the storage tank ≥ 18 m 2 / m 2), the transcritical compressed CO2 fluid flows back and forth from the inlet to the outlet through the heat exchanger tube to release heat through the fins outside the tube to transfer to the supercritical CO2 energy storage medium enclosed in the storage tank through natural convection isochoric heat absorption to increase the temperature and pressure to a supercritical state, thereby directly converting the heat that the usual compression air conditioner needs to take away with the coolant into the high-level thermal enthalpy of the CO2 energy storage medium (for example, 70MPa / 210℃ / 700kg.m -3 / 850kJ.kg -1 ), and then convert this enthalpy into the power output of the expander in the energy release process, the ratio of its power consumption to the transcritical compression CO2 (energy storage cycle efficiency) is not less than 0.70, and its (24-hour cycle) energy storage volume density is not less than 6.0kWh.m -3 , especially the cooling / heating performance coefficient of the air conditioner coupled with it is comparable to that of a single air conditioner. The method of the present invention is significantly superior to the existing technology in terms of energy utilization efficiency, energy storage efficiency and energy storage volume density, and provides an efficient and practical technology for the combined (especially distributed) utilization of periodic power storage / use such as wind, light, water, and "valley". Summary of the invention

[0005] The present invention discloses an isochoric thermobaric CO2 energy storage and air conditioning integrated circulation system and method. The circulation system includes an array of vertically arranged storage tanks 10 (with a heat exchanger 11 built in the storage tank, and the tank body is resistant to 60-80MPa high pressure and 10-220°C variable temperature and pressure alternating stress). All storage tanks (and their built-in heat exchangers) have the same structure and can be interchanged. The interfaces on the storage tanks are connected to the corresponding main pipes (including the connection between the CO2 energy storage medium inlet at the bottom of the storage tank and the energy storage medium input main pipe 5, the connection between the supercritical CO2 energy release medium outlet at the top of the storage tank and the output main pipe 6, the connection between the built-in heat exchanger inlet and the energy storage compressor main pipe 7 or the air conditioning compressor main pipe 17, the connection between the built-in heat exchanger outlet and the energy storage expander main pipe 8 or the air conditioning expander main pipe 18, and the connection between the connecting pipes 9 between adjacent heat exchangers in the array) in the same corresponding manner. Each of the main pipes 5, 6, 7, 8, 17, and 18 forms a parallel manifold. The automatic control valves 12 to 16 are used to switch the connection / disconnection status of each tank and each main pipe, thereby switching the tank operation cycle and dynamically partitioning the tank. All tanks can cycle through the various dynamic partitioning stages described below:

[0006] Attached Figure 1 The refrigeration and energy storage coupling cycle stage is shown in the figure. The dotted box 1 includes the dynamic sequence C1, C2, ..., C n-1 , C n The C combination hot pressing dynamic partition stage (hereinafter referred to as the C combination hot pressing stage) consists of n (n = 10 to 18) storage tanks. The storage tanks that dynamically enter this stage are already filled with 6.4 to 6.8 MPa, 25 to 28 ° C, 655 to 710 kg / m 3The CO2 energy storage medium, with the top outlet stop valve 15 and the bottom inlet stop valve 16 of the storage tank closed, forms a closed constant-volume space. The energy storage compressor 21 sucks in saturated CO2 gas at 4.0 - 4.8 MPa from the CO2 spherical tank 20 (which can be superheated to above 40 °C through the waste heat recovery heat exchanger 29), and adiabatically compresses it transcritically to no more than 50 MPa, with the compression work (isentropic) not exceeding 120 kJ / kg and the temperature not exceeding 230 °C. Then it enters the double-pass inside the tube of the heat exchanger 11 built into the C1 storage tank through the main pipe 7 from the opened changeover valve 14, and the temperature drop during heat release does not exceed 16 °C. Then it flows out from the opened outlet stop valve 12 and changeover valve 13 and flows through the connecting pipe 9 into the heat exchanger built into the adjacent C2 storage tank to continue heat release and temperature drop not exceeding 16 °C. This similar process is continuously transferred to the downstream storage tanks until C n , and the process lasts for 5 - 20 minutes to heat the closed CO2 energy storage medium in the C1 storage tank at constant volume, increasing the temperature and pressure to 170 °C and above 60 MPa, achieving an energy storage density not lower than 790 kJ / kg. The changeover valve 14 and the stop valve 12 are automatically closed to make the C1 storage tank dynamically exit the C combination hot pressing stage and enter the energy release waiting stage (detailed later). At the same time, a storage tank that has been filled with the CO2 energy storage medium enters the C combination hot pressing stage to take over C n sequence number, so that the number of storage tanks included in the C combination hot pressing stage and the cycling mode remain unchanged, and all the dynamic sorting of the storage tanks moves one position number in the C1 direction. In the storage tank array of the C combination hot pressing stage, the CO2 temperature and pressure in the C1 storage tank are always the highest. As the digital number of the dynamic sorting increases, the temperature and pressure of each storage tank decrease, until C n In the storage tank, the temperature and pressure of the CO2 energy storage medium that is undergoing isochoric endothermic heating and pressure increase do not exceed 38 °C / 18 MPa. After flowing through the heat exchanger built into the storage tank and releasing heat, the transcritical compressed CO2 cools down to no higher than 45 °C. It enters the energy storage / energy release expander 22 through the opened stop valve 12 and changeover valve 13 and the outlet main pipe 8, adiabatically expands to 8 - 9 MPa, and outputs work (isentropic) of 25 - 40 kJ / kg. Then it directly enters the transcritical energy storage ejector 23 through the opened changeover valve 30 to form a supersonic jet to attract the superheated CO2 gas flow at 3.5 - 4.4 MPa and not exceeding 25 °C from the CO2 evaporator 27 and mixes with it to form a subcritical gas-liquid two-phase flow and returns to the CO2 spherical tank 20.

[0007] Figure 1 The refrigeration and energy storage coupling cycle stage shown by the dashed box 2 consists of the D combination hot pressing dynamic zoning stage (hereinafter referred to as the D combination hot pressing stage) composed of i (i = 12 - 20) storage tanks such as the dynamic sorting D1, D2,..., D i-1 , D i etc., and it is related to Figure 1The working principle, pipeline and valve connections, and automatic control opening and closing methods of the C combination shown in the dashed box 1 are all the same. The differences are as follows: The number of storage tanks i in the hot pressing stage of the D combination is different from the number of storage tanks n in the C combination area. Connected to the inlet of the heat exchanger inside the D1 storage tank is the main pipe 17 of the air-conditioning compressor, and connected to the outlet of the heat exchanger inside the D i storage tank is the main pipe 18 of the air-conditioning expander, and there is no connecting pipeline between this main pipe and the main pipe 6 for the output of the energy release medium. The hot pressing stage of the D combination and the operation process of the coupled refrigeration and air-conditioning are as follows: The enclosed spaces of the storage tanks entering the hot pressing stage of the D combination are filled with the energy storage medium CO2 at 6.5 - 7.2 MPa, 25 - 30 °C, and 590 - 730 kg / m 3 The air-conditioning compressor 24 sucks in a superheated CO2 gas stream with a pressure of 3.5 - 4.4 MPa and a temperature not exceeding 25 °C (which can be heated to above 40 °C through the waste heat recovery heat exchanger 29) from the CO2 evaporator 27, and adiabatically compresses it transcritically to not exceed 40 MPa, with an isentropic compression work not exceeding 140 kJ / kg and a temperature not higher than 250 °C. It enters the tube side of the heat exchanger 11 inside the D1 storage tank to release heat and is connected in series through D2, …, D i-1 、D i the heat exchangers inside each storage tank to release heat, causing the energy storage medium CO2 enclosed in the storage tank that dynamically enters the hot pressing stage of the D combination and is sequenced progressively as D1 to be heated isochorically to a temperature of 210 °C and a pressure of 58 MPa or more, reaching an energy storage density of not less than 850 kJ / kg. The reversing valve 14 and the stop valve 12 are automatically closed to make the D1 storage tank dynamically exit the hot pressing stage of the D combination and enter the energy release waiting stage. The transcritical compressed CO2 gas stream flows through the heat exchangers inside the storage tanks in the hot pressing stage of the D combination in series and sequentially to release heat and cool down to not higher than 40 °C, enters the air-conditioning expander 25 through the outlet main pipe 18, adiabatically expands to 8 - 9 MPa, with an output work (isentropic) of 30 - 50 kJ / kg, and then enters the transcritical air-conditioning ejector 26 to form a supersonic jet to attract the superheated CO2 gas stream from the CO2 evaporator 27 and mix with it to form a subcritical gas-liquid two-phase flow, which also returns to the spherical tank 20.

[0008] The ratio of the mass flow rate of sucking the CO2 evaporator 27 by the energy storage ejector 23 to the mass flow rate of the energy storage compressor 21 (entrainment coefficient) is 0.2 - 0.6, and the entrainment coefficient of sucking the CO2 evaporator 27 by the air-conditioning ejector 26 is also 0.2 - 0.6. Therefore, the evaporation amount of the evaporator 27 is 1.2 - 1.6 times the mass flow rate of the air-conditioning compressor 24 plus 0.2 - 0.6 times the mass flow rate of the energy storage compressor 21. The dryness (ratio of the gas-phase mass flow rate to the total mass flow rate of the two-phase flow) of the subcritical gas-liquid two-phase flow entering the CO2 spherical tank 20 from the ejectors 23 and 26 is both 10 - 30%.

[0009] Appendix Figure 2As shown, in the stage of coupling cycle of CO2 refrigeration and energy release, the connection valve between the inlet of the energy storage / energy release expander 22 and the main pipe 8 is closed, the connection valve with the main pipe 6 for output of the energy release medium is opened at the same time, and the outlet reversing valve 30 of the expander 22 is switched so that the energy release medium enters the ejector 23 after passing through the waste heat recovery heat exchanger 29, thus making the system enter the energy release stage. The energy release process is divided into two time periods, respectively targeting two groups of storage tanks ΣC and ΣD that enter the stage of waiting for energy release through the C combined hot pressing stage and the D combined hot pressing stage in the aforementioned energy storage stage. The CO2 energy storage parameters in the ΣC group of storage tanks are that the temperature is higher than 170 °C, the pressure is greater than 60 MPa, and the energy storage density is greater than 790 kJ / kg. The corresponding temperature / pressure / energy storage density of the ΣD group of storage tanks is not lower than 210 °C / 58 MPa / 850 kJ / kg.

[0010] Appendix Figure 2 As shown by the dashed box 3, it is the dynamic partition time period of energy release of the ΣC group of storage tanks. Open the top outlet stop valves 15 of all storage tanks in the ΣC group so that the entire group of storage tanks is connected in parallel through the main pipe 6 for output of the energy release medium. The stored energy medium CO2 in each storage tank synchronously flows into the main pipe 6 and is input into the expander 22 to do work. The pressure and density of the stored energy medium decrease as the amount of the medium in the storage tank decreases, and the output expansion work (130 - 20 kJ / kg, isentropic) also decreases accordingly. The weighted average value according to the density of the stored energy medium is 70 - 100 kJ / kg. The pressure of the energy release medium at the outlet of the expander is 8 - 9 MPa, and the temperature is not lower than 45 °C. It releases heat and cools down to no higher than 30 °C through the waste heat recovery heat exchanger 29, enters the ejector 23 to suck the 3.5 - 4.4 MPa superheated CO2 gas flow from the evaporator 27 and mixes and pressurizes it into a subcritical gas-liquid two-phase flow and returns to the spherical tank 20 for storage. When the pressure of the energy release medium at the inlet of the expander drops to less than 10.5 MPa, the energy release time period of the ΣC group of storage tanks ends, and the top outlet stop valves 15 of each storage tank are closed, making this group of storage tanks dynamically transfer to the stage of waiting to be filled (with the stored energy medium).

[0011] Appendix Figure 2 As shown by the dashed box 4, it is the dynamic partition time period of energy release of the ΣD group of storage tanks, which does not overlap with the energy release time period of the ΣC group. The parallel connection method of the storage tanks corresponding to the energy release time period of the ΣD group with the main pipe 6 for output of the energy release medium and the operation modes of the expander 22, the waste heat recovery heat exchanger 29, and the ejector 23 are all the same as those in the energy release time period of the above ΣC group. The difference is only that the range of the decreasing output expansion work with the decreasing pressure and density of the energy release medium at the inlet of the expander is 140 - 30 kJ / kg (isentropic), and the weighted average value according to the density of the stored energy medium is 80 - 110 kJ / kg.

[0012] All storage tanks that dynamically enter the waiting stage through the CO2 refrigeration and energy release coupling cycle stage can pressurize the liquid CO2 with a pressure pump 28 and absorb heat through a waste heat recovery heat exchanger 29 to heat it to the required density and temperature under the premise that the liquid volume in the CO2 spherical tank 20 accounts for more than 10% of the total volume. The tank is filled from the energy storage medium input main pipe 5 through the liquid phase inlet stop valve 16 at the bottom of the storage tank that is opened tank by tank, and then the valve is closed to allow the tank to dynamically enter the waiting stage for energy storage.

[0013] Through the automatic control of each tank valve and pipeline network, Figure 1 and attached Figure 2 The CO2 refrigeration-energy storage and refrigeration-energy release coupling cycles shown can be operated simultaneously or separately. The CO2 evaporator 27 absorbs the heat enthalpy of the ambient air intake, and the CO2 evaporation pressure is 3.5-4.4 MPa and the evaporation temperature is 1-9°C, thereby adjusting the temperature and humidity of the comfortable air conditioning cool air or providing a 4-5°C cold water cycle for public works.

[0014] According to the above-mentioned CO2 refrigeration and energy storage / release coupled cycle system and method, it is only necessary to add air conditioning heaters A and B (31 and 32) and an air conditioning ejector outlet gas-liquid separator (33) and adjust the cycle process temperature and pressure range to be used for heating and energy storage / release coupled cycle. Figure 3 The heating-energy storage coupled cycle system shown in the dashed box 2 is similar to the above-mentioned Figure 1 The dotted box 2 corresponds to the combined heat pressure stage of refrigeration-energy storage D. The difference between the two is that in the heating-energy storage cycle stage, the CO2 evaporator 27 absorbs heat from the ambient air at a lower temperature (not less than -40°C), and after evaporation at a lower pressure (not less than 0.8MPa), 30-40% (mass%) directly enters the primary air intake duct of the two-stage air intake air conditioning compressor 24, and 60-70% passes through the air conditioning ejector 26 with an ejection coefficient of 0.2-0.6 for pre-pressurization of 0.2 ~0.4MPa, after being defogged by the gas-liquid separator 33, it enters the secondary air inlet of the compressor and is compressed to a temperature and pressure not exceeding 250℃ / 40MPa across the critical pressure. Then, it passes through the built-in heat exchangers of all (no more than 18) storage tanks of the ΣD group in sequence to heat the energy storage medium in the tank (6~6.7MPa / 22~27℃) to increase the temperature and pressure at the same volume, and gradually make the first tank (D1) reach the supercritical energy storage parameters (no more than 220℃ / 80MPa / 860kJ·kg -3 ), transcritical compression CO2 from ΣD group end tank (D i) After the built-in heat exchanger releases heat, the outlet temperature drops to no less than 40°C, enters the air conditioner heater A(31) through the outlet main pipe 18 and continues to release heat to further drop the temperature to more than 5°C higher than the ambient atmospheric temperature, then enters the air conditioner expander 25 to do work of no less than 20 kJ / kg (isentropic), and then through the air conditioner ejector 26, the supersonic jet attracts the low-pressure CO2 steam of the evaporator 27 and mixes with it to boost the pressure to 0.2 - 0.4 MPa higher than the evaporation pressure of 27. The gas-liquid two-phase flow enters the gas-liquid separator 33. The gas enters the secondary intake passage of the compressor 24 for pressurized circulation, and the liquid enters the low-temperature evaporator 27 through the throttle valve to absorb heat and vaporize for circulation. Thus, it constitutes the attached Figure 3 The heating - energy storage coupling cycle shown by the dashed line box 2. The ambient air is heated to more than 20°C by the air conditioner heater A(31) for air supply.

[0015] Attached Figure 3 The heating - energy release coupling cycle shown by the dashed line box 3, corresponding to the refrigeration - energy release ΣC group shown by the attached Figure 2 dashed line box 3. The difference between the two is that in the heating - energy release cycle stage, the CO2 energy storage medium (temperature and pressure not exceeding 220°C / 80 MPa) in all storage tanks of the ΣC group converges into the main pipe 6, does work through the expander 22, and its outlet pressure is 6.3 - 6.8 MPa and temperature is 28 - 65°C. After continuing to release heat and cooling through the air conditioner heater B(32) and condensing, it directly enters the CO2 spherical tank 20. Thus, it constitutes the attached Figure 3 The heating - energy release coupling cycle shown by the dashed line box 3. In this cycle stage, the expansion Machine output expansion work (120 - 25 kJ / kg, isentropic) decreases as the pressure and density of the energy storage medium CO2 decrease, and the output also decreases accordingly. The weighted average value according to the density of the energy storage medium is 70 - 100 kJ / kg (isentropic). When the expansion Machine inlet pressure drops to less than 8.5 MPa, the heating - energy release of the ΣC group storage tanks ends. Close the outlet stop valves 15 at the top of each storage tank to dynamically transfer this group of storage tanks to the waiting - filling stage, and use the medium in the spherical tank 20 to fill them one by one through the pressurizing pump 28. Thus, it constitutes the attached Figure 3 The heating - energy release coupling cycle shown by the dashed line box 3. The air conditioner inlet air is heated to more than 20°C by the air conditioner heater B(32) for air supply. Brief Description of the Drawings

[0016] Figure 1 、 Figure 2 And Figure 3 are schematic diagrams of the refrigeration - energy storage coupling and heating - energy storage coupling methods of the isochoric hot - pressed CO2 energy storage and air conditioner integrated cycle system provided by the present invention.

[0017] Figure 1 、 Figure 2 And Figure 3In Chinese: 1, 2, 3, 4 – System circulation dynamic partition codes; 5 – Total inlet pipe of energy storage medium; 6 – Total outlet pipe of energy release medium; 7 – Total inlet pipe of built-in heat exchanger in C combination; 8 – Total outlet pipe of built-in heat exchanger in C combination; 9 – Connecting pipe of built-in heat exchanger; 10 – Variable temperature and pressure CO2 storage tank; 11 – Double-pass tubular external fin heat exchanger inside the storage tank; 12 – Stop valve at the outlet of the built-in heat exchanger; 13 – Reversing valve between the main pipe 8 and the connecting pipe 9; 14 – Reversing valve between the main pipe 7 and the connecting pipe 9; 15 – Stop valve at the outlet of the storage tank; 16 – Stop valve at the inlet of the storage tank; 17 – Total inlet pipe of built-in heat exchanger in D combination; 18 – Total outlet pipe of built-in heat exchanger in D combination; 20 – CO2 spherical tank; 21 – Energy storage compressor; 22 – Energy storage / energy release expander; 23 – Energy storage / energy release ejector; 24 – Air-conditioning compressor; 25 – Air-conditioning expander; 26 – Air-conditioning ejector; 27 – CO2 evaporator; 28 – Pressurizing pump; 29 – Heat recovery heat exchanger for expander waste heat; 30 – Reversing valve for waste heat recovery; 31 – Air-conditioning heater A; 32 – Air-conditioning heater B; 33 – Gas-liquid separator at the outlet of the air-conditioning ejector; (C1, C2, …, Cn-1, Cn) – Tank numbers of C-type dynamic partition storage tanks; (D1, D2, …, Dn-1, Dn) – Tank numbers of D-type dynamic partition storage tanks. Detailed implementation manners

[0018] The following describes the specific implementation manners of the present invention in combination with, but not limited to, embodiments.

[0019] Embodiment 1: Using the CO2 energy storage and air-conditioning refrigeration integrated cycle system and method of the present invention, with a 24-hour cycle (the energy storage period lasts for 8 hours, the energy release period lasts for 16 hours and the two periods do not overlap, and the air-conditioning refrigeration is continuous for 24 hours). The operating power of the energy storage compressor is 42.2 kW, the operating power of the air-conditioning compressor is 25 kW, and the isentropic efficiency of both is 0.8; the isentropic efficiency of the expander is 0.85. There is one spherical tank with a pressure resistance of 8 MPa and an effective volume of 30 m 3 , 68 tubular (straight pipe section length 6 m, inner diameter 0.4 m) storage tanks with a pressure resistance of 80 MPa, the effective volume of a single tank is 0.78 m 3 , and the effective heat transfer area of the double-pass tubular fin heat exchanger inside the storage tank is 145 m 2 . The ambient temperature is 35 °C, and the air-conditioning refrigeration supply temperature is 22 °C.

[0020] According to Figure 1 and Figure 2 the corresponding implementation methods, the storage tank C combination is formed with n = 16, and the storage tank D combination is formed with i = 18.

[0021] During the 8-hour energy storage period, it operates according to the refrigeration and energy storage coupling cycle stage shown in the appendix Figure 1 , and the C combination and D combination of the storage tanks to be energy-stored that dynamically enter this stage are all filled with 6.5 MPa, 26.5 °C, 700 kg / m 3The CO2 energy storage medium, with the top outlet stop valve 15 and the bottom inlet stop valve 16 of the storage tank closed, forms a closed constant-volume space. Energy storage Compressor 21 sucks in 4.5 MPa saturated CO2 gas from the CO2 spherical tank 20, undergoes transcritical adiabatic compression (isentropic compression work of 115 kJ / kg) to 43 MPa and 215 °C, enters the built-in heat exchanger of the C1 storage tank through the main pipe 7 from the opened changeover valve 14 to release heat and reduce the temperature by 10 - 11 °C, then flows out from the opened outlet stop valve 12 and changeover valve 13 and enters the built-in heat exchanger of the adjacent C2 storage tank through the connecting pipe 9 to continue releasing heat and reducing the temperature by 10 - 11 °C, and so on until it flows out of the built-in heat exchanger of the storage tank C 16 After releasing heat from the built-in heat exchanger of the storage tank, the outlet temperature is 37 - 42 °C. This process lasts for 15 minutes, causing the energy storage medium in the C1 storage tank to be heated and increase in temperature and pressure isochorically to the energy storage state of 200 °C, 70 MPa, and an energy storage density of 830 kJ / kg. Automatically close the changeover valve 14 and stop valve 12 of the C1 storage tank to make this storage tank dynamically exit the C combination hot pressing stage and enter the energy release waiting state. At the same time, a storage tank waiting to store energy that has been filled with the above energy storage medium enters the C combination hot pressing stage to replace C 16 Serial number. Transcritical compressed CO2 sequentially passes through C1 - C 16 After all the built-in heat exchangers of the storage tanks release heat to C 16 The outlet temperature of the heat exchanger is 37 - 42 °C. It enters the energy storage / energy release expander 22 through the outlet main pipe 8 from the opened stop valve 12 and changeover valve 13 and undergoes adiabatic expansion to 9 MPa / 12 °C, outputting work (isentropic) of 35 - 40 kJ / kg, and then directly enters the transcritical energy storage ejector 23 through the opened changeover valve 30 to form a supersonic jet (entrainment coefficient 0.2) to attract the 4 MPa and 24 °C superheated CO2 gas flow from the CO2 evaporator 27 and mix and pressurize it to return to the CO2 spherical tank 20.

[0022] During the 8-hour energy storage period, as shown in the appendix Figure 1 The air-conditioning compressor 24 sucks in the 4.0 MPa and 24 °C superheated CO2 gas flow from the CO2 evaporator 27, undergoes transcritical adiabatic compression (isentropic compression work of 115 kJ / kg) to 30 MPa and 225 °C, enters the D1 built-in heat exchanger through the main pipe 17 from the opened changeover valve 14 of the D1 storage tank to release heat and reduce the temperature by 10 - 11 °C, then flows out of D1 from the opened outlet stop valve 12 and changeover valve 13 and enters the built-in heat exchanger of the adjacent D2 storage tank through the connecting pipe 9 to continue releasing heat and reducing the temperature by 10 - 11 °C, and so on until it flows out of the storage tank D 18The outlet temperature of the built-in heat exchanger after heat release is 40-45°C. The process lasts for 13.33 minutes, causing the energy storage medium in the D1 storage tank to be heated and isochorically increased in temperature and pressure to 210°C, 70 MPa, and a storage energy density of 850 kJ / kg. The changeover valve 14 and stop valve 12 of the D1 storage tank are automatically closed, causing the storage tank to dynamically exit the D combined hot pressing stage and enter the energy release waiting state. At the same time, a waiting energy storage tank enters the D combined hot pressing stage to replace D 18 Serial number. The CO2 sequentially compressed by the air-conditioning compressor 24 in a transcritical manner passes through the built-in heat exchangers of all storage tanks in the D combination in series and releases heat before reaching D 18 The outlet temperature of the heat exchanger drops to 40-45°C. From the opened D 18 The stop valve 12 and changeover valve 13 enter the air-conditioning expander 25 through the outlet main pipe 18 and adiabatically expand to 9 MPa / 12°C, outputting work (isentropic) of 25-30 kJ / kg, and then directly enter the transcritical air-conditioning ejector 26 to jet (entrainment coefficient 0.2) to attract the 4 MPa, 24°C superheated CO2 gas flow from the evaporator 27 and mix and pressurize it to return to the CO2 spherical tank 20.

[0023] The 16-hour energy release period operates according to the refrigeration and energy release coupling cycle stage shown in the appendix Figure 2 The connecting valve between the inlet of the energy storage / energy release expander 22 and the main pipe 8 is closed, and the connecting valve with the energy release medium output main pipe 6 is opened. At the same time, the outlet changeover valve 30 of 22 is switched so that the energy release medium enters the ejector 23 after passing through the waste heat recovery heat exchanger 29. The energy release process respectively targets the storage tank arrays ΣC (2 groups, 16 tanks in each group) and ΣD (2 groups, 18 tanks in each group) that have completed isochoric hot pressing of CO2 through the C combination and D combination and entered the energy release waiting stage in the aforementioned energy storage stage. The top outlet stop valves 15 of the energy storage tanks in the ΣC group or ΣD group are opened in groups to achieve parallel connection through the energy release medium output main pipe 6, so that the energy storage media in each group are synchronously input into the expander 22 to do work (isentropic expansion work of 120-20 kJ / kg decreases as the density or pressure of the energy release medium in the storage tank decreases). The average energy release period of each group of storage tanks is 4 hours, and its average energy release power is 35.4 kW. The pressure of the energy release medium at the outlet of the expander is 9 MPa, and the temperature is 50-100°C. After releasing heat (heating the gas at the inlet of the air-conditioning compressor 24 and heating the energy storage medium for charging the storage tank) through the waste heat recovery heat exchanger 29, the temperature drops to 14-15°C, enters the ejector 23 to suck (entrainment coefficient 0.2) the 4 MPa / 24°C superheated CO2 gas flow from the evaporator 27 and mixes and pressurizes it to return to the spherical tank 20 for storage. The energy release of this group of storage tanks lasts for 4 hours, and the pressure of the energy release medium at the inlet of the expander drops to 10-10.5 MPa. The top outlet stop valves 15 of each storage tank are closed, causing this group of storage tanks to enter the waiting (energy storage medium) stage. At the same time, the energy release medium output main pipe 6 is switched to be connected in parallel with another group of storage tanks, and another 4-hour energy release period begins.

[0024] In one cycle (24 hours) of this embodiment: the 25kW air conditioning CO2 compressor runs continuously for 24 hours, and the 42.2kW energy storage compressor runs for 8 hours; the average refrigeration load for 24 hours is 58kW, the air conditioning expander recovers 4.1kW of power in 24 hours, the energy storage expander recovers 9.98kW of power in 8 hours, and the average power of the energy release expander recovers 35.39kW in 16 hours. Therefore, the energy storage-refrigeration coupling cycle takes the total power consumption of the air conditioning compressor and the energy storage compressor as the base, the energy storage efficiency is 0.795, and the average energy storage volume density is 8.92kWh / m 3 ; Taking the difference between the power consumed by the air-conditioning compressor and the power recovered by the air-conditioning expander as the base, the refrigeration COPc is 2.78.

[0025] Example 2: The CO2 energy storage and air conditioning heating integrated circulation system and method of the present invention is used, with a cycle of 24 hours (the energy storage period lasts for 8 hours, the energy release period lasts for 16 hours, and the two periods do not overlap, and the air conditioning heating is continuous for 24 hours). The air conditioning compressor has an 8-hour operating power of 121.2kW and an isentropic efficiency of 0.8; the energy release expander has an average output power of 37.4kW and an isentropic efficiency of 0.85 in 16 hours. A pressure-resistant 8MPa spherical tank with an effective volume of 30m 3 , 68 80MPa pressure-resistant tubular storage tanks (straight pipe length 6m inner diameter 0.4m), single tank effective volume 0.78m 3 , The tank has a built-in two-way tubular fin heat exchanger with an effective heat exchange area of ​​145m 2 The ambient temperature is -15℃, and the air temperature of the air conditioner is 22℃.

[0026] During the 8-hour heating-energy storage coupling cycle, the storage tank is filled with 6.5MPa / 25.5℃ / 700kg·m -3 Saturated liquid CO2. Figure 3 As shown in the dotted box 2, the heat-absorbing CO2 evaporator 27 from the -15℃ environment evaporates 3231.1kg / h of CO2 gas at (-20℃ / 2MPa) (40% of which directly enters the primary air intake duct of the two-stage air intake air-conditioning compressor 24, and 60% enters the secondary air intake duct of the compressor after being pre-pressurized by 0.4MPa through the air-conditioning ejector 26 jet and defogged by the gas-liquid separator 33), and is compressed to 190℃ / 22MPa across the critical point. The heat is released sequentially through the built-in heat exchangers of all the storage tanks of the energy storage D combination (dynamically composed of 16 storage tanks), so that the energy storage medium in the tank is heated and pressurized at the same volume, and the first tank (D1) reaches the supercritical energy storage parameter of 180℃ / 62MPa / 800kJ·kg one by one (tank replacement cycle 7.5min). -3 , the last tank (D 16) The CO2 at the outlet of the heat exchanger is cooled to 40°C, enters the air conditioner heater A (31) through the outlet main pipe 18, continues to release heat of 95 kJ / kg, is cooled to -10°C, then enters the air conditioner expander 25 and expands to 8 MPa to do work of 20 kJ / kg (isentropic). Then, it forms a supersonic jet (entrainment coefficient 0.6) through the air conditioner ejector 26 to attract the 2 MPa saturated CO2 steam in the evaporator and mix with it to boost the pressure to 2.4 MPa for the gas-liquid two-phase flow to enter the gas-liquid separator 33. After separation, the gas enters the secondary intake passage of the compressor 24, and the liquid passes through the throttle valve to enter the low-temperature evaporator 27 to absorb heat and vaporize, thus forming an attached Figure 3 As shown by the dotted line box 2, for the 8-hour heating-energy storage coupling cycle, the fresh air at -15°C is 6700 Nm 3 / h, absorbs heat of 85.3 kW through the air conditioner heater A (31), and the temperature rises to above 20°C for air supply.

[0027] During the 16-hour heating-energy release coupling cycle period, the parameters of the energy storage medium in 64 supercritical CO2 storage tanks are 180°C / 62 MPa / 800 kJ·kg -3 / 700 kg·m -3 , the storage tanks are divided into 4 energy release ΣC groups (16 tanks in each group), and the energy release duration of each group is 4 hours. As shown by the attached Figure 3 dotted line box 3, after the energy storage media in all the storage tanks of 1 ΣC group flow into the main pipe 6 and do work through the energy release expander 22, the outlet pressure is 6.5 MPa and the temperature is 26 - 62°C. Then, it releases heat through the air conditioner heater B (32), cools and condenses into a 25.5°C saturated liquid and directly enters the CO2 spherical tank 20, thus forming a heating-energy release coupling cycle. The output power of the energy release expander decreases in the range of 110 - 25 kJ / kg (isentropic) as the CO2 pressure and density of the energy storage medium in this group decrease with time, and the weighted average value by density during the energy release process is 71.9 kJ / kg (isentropic). When the inlet pressure of the expander drops to less than 8.5 MPa, the heating-energy release of this group of storage tanks ends, and the outlet stop valves 15 at the top of each storage tank are closed to dynamically transfer this group of storage tanks to the waiting-to-be-filled stage. At the same time, the energy release medium flows into the main pipe 6 and is connected to another ΣC group to start another 4-hour energy release period. Use the pressurizing pump 28 to fill each of the storage tanks waiting to be filled after energy release with the 6.5 MPa / 25.5°C saturated liquid CO2 in the spherical tank 20 one by one. Thus, it forms an attached Figure 3 As shown by the dotted line box 3 for the 16-hour heating-energy release coupling cycle, the air intake circulation volume of the 10°C air conditioner is 26310 Nm 3 / h, absorbs heat of 95.2 kW through the air conditioner heater B (32), and the temperature rises to above 20°C for air supply.

[0028] Example 2: Within a 24-hour cycle, during the 8-hour heating and energy storage period, the circulating volume of the CO2 air conditioner compressor is 3231.1 kg / h, the power consumption is 121.2 kW, the recovered power of the air conditioner expander is 15.3 kW, and the net power consumption of the 8-hour compression cycle is 105.9 kW. Based on this power consumption, 85.3 kW of heat is obtained through the air conditioner heater A during the 8-hour heating and energy storage period, and an average of 95.2 kW of heat is obtained through the air conditioner heater B and an average power output of 37.4 kW is obtained through the energy release expander during the 16-hour heating and energy release period. The energy storage efficiency based on the net power consumption of the 8-hour compression cycle is 0.71, and the average energy storage volume density is 7.44 kWh / m 3 , and the heating COPh is 2.6.

[0029] The present invention is not limited to the above embodiments, and its technical solutions have been described in the section of the invention content.

Claims

1. An isochoric heat-pressed CO2 energy storage and air-conditioning integrated cycle system and method, characterized in that The system includes a spherical tank with a pressure not exceeding 8 MPa and several 80 MPa high-pressure vertical variable-temperature and variable-pressure storage tanks. Each storage tank and its built-in double-pass tubular external fin heat exchanger are connected to equipment such as a transcritical CO2 compressor, expander, ejector, CO2 evaporator, and air-conditioning supply air heater through a pipe network controlled by automatic valves, and the combination mode and operation cycle are switched. During the energy storage process, the heat energy input from the environment and generated by compression is collected and transferred to the supercritical CO2 energy storage medium enclosed in the storage tank through transcritical compressed CO2 fluid, causing it to undergo natural convection and isochoric endothermic heating and pressure increase to a high enthalpy state. During the energy release process, this enthalpy is converted into the power output of the expander, and the ratio of the power output during the energy release process to the power consumed during the energy storage process is not less than 0.

70. Additionally, it also couples and absorbs refrigeration / heating benefits equivalent to that of a conventional standalone air conditioner. The heat-pressure dynamic partition of the storage tank connected to the outlet main pipe of the energy storage compressor in the refrigeration and energy storage coupling cycle stage consists of 10 to 18 storage tanks filled with a CO2 energy storage medium at 6.4 to 6.8 MPa, 25 to 28 °C, and 655 to 710 kg / m 3 Each storage tank forms a closed isochoric space. The double-pass tube-type external fin heat exchangers installed in all storage tanks form a series combination from start to end through the connecting pipes between the outlets and inlets. The energy storage compressor sucks in CO2 gas at 4.0 to 4.8 MPa, saturated or superheated to above 40 °C, from the CO2 spherical tank and adiabatically compresses it transcritically to no more than 50 MPa / 230 °C. It sequentially flows through the inside of each heat exchanger in the heat-pressure dynamic partition from the inlet of the heat exchanger installed in the first storage tank in the series to the outlet of the last one, releasing heat and the temperature decreasing by no more than 16 °C. This process lasts for 5 to 20 minutes, causing the energy storage medium in the first storage tank to increase in temperature and pressure and first reach above 170 °C / 60 MPa, with its energy storage density not lower than 790 kJ / kg. The automatic control valve causes this storage tank to exit the heat-pressure cycle stage, and at the same time, a storage tank to be energy-stored is supplemented at the tail of the series combination. In this way, the temperature and pressure of the energy storage medium in the storage tank at the head of the series combination are always the highest, and the temperature and pressure decrease to no more than 38 °C / 18 MPa at the tail storage tank. The transcritical compressed CO2 leaving the outlet of the heat exchanger installed in the tail storage tank is cooled to no higher than 45 °C, outputs an isentropic work of 25 to 40 kJ / kg through the energy storage expander, and then expands in pressure to 8 to 9 MPa. Then, through a transcritical energy storage ejector with an entrainment coefficient of 0.2 to 0.6, it forms a supersonic jet to attract the superheated CO2 gas flow at 3.5 to 4.4 MPa and no higher than 25 °C from the CO2 evaporator and mixes with it to form a gas-liquid two-phase flow with a dryness of 10 to 30% and returns to the CO2 spherical tank, thereby completing the liquefaction of the CO2 gas in the spherical tank and energy storage; The thermal pressure dynamic zoning of the storage tank connected to the main pipe at the outlet of the air-conditioning compressor during the refrigeration and energy storage coupling cycle is for 12 to 20 storage tanks filled with a CO2 energy storage medium at 6.5 to 7.2 MPa, 25 to 30 °C, and 590 to 730 kg / m 3 The heat exchangers inside the storage tanks are connected in series. The air-conditioning compressor sucks in a CO2 gas stream at 3.5 to 4.4 MPa and not exceeding 25 °C or heated to over 40 °C through waste heat recovery from the CO2 evaporator, and compresses it transcritically to not exceeding 40 MPa / 250 °C. The compressed CO2 gas flows sequentially through the inside of each heat exchanger tube from the inlet of the first heat exchanger inside the storage tank in the series combination to the outlet of the last one, releasing heat in the process. This gradually causes the energy storage medium in the storage tanks dynamically entering this combination to absorb heat and increase in pressure isochorically until it reaches 210 °C / 58 MPa or higher, achieving a storage energy density of not less than 850 kJ / kg. After releasing heat, the transcritically compressed CO2 fluid flows out of the heat exchanger of the last storage tank at a temperature not higher than 40 °C, outputs an isentropic work of 30 to 50 kJ / kg through the air-conditioning expander, and the pressure drops to 8 to 9 MPa. Then, through a transcritical air-conditioning ejector with an entrainment coefficient of 0.2 to 0.6, it forms a supersonic jet to attract the superheated CO2 gas stream from the CO2 evaporator and mixes with it to form a gas-liquid two-phase flow with a dryness of 10 to 30%, which also returns to the CO2 spherical tank. Thus, the gasification of CO2 in the evaporator and its liquefaction and energy storage are completed; The pipeline connection controlled by the automatic valve, the energy storage tanks completed by the cycle driven by the energy storage compressor and the cycle driven by the air-conditioning compressor respectively enter the refrigeration and energy release coupling cycle stage. 16 to 18 energy storage tanks form a group of energy release dynamic partition combinations. Through the main energy release medium output pipe, all the tanks in the group are connected in parallel, and the energy storage medium CO2 in each tank is synchronously input into the energy release expander to do work. The duration is 2 to 4 hours. The output expansion work decreases as the pressure and density of the energy storage medium in the tank decrease. The isentropic expansion work weighted by density is 70 to 110 kJ / kg. When the expansion Machine When the inlet medium pressure drops to less than 10.5 MPa, the energy release period of this group of energy storage tanks ends, and the outlet stop valves at the top of each tank are closed to dynamically transfer this group of tanks to the waiting-for-charging stage; the outlet medium pressure of the energy release expander is 8 to 9 MPa, and the temperature is not lower than 45 °C. It is cooled to no higher than 30 °C through the waste heat recovery heat exchanger, enters the energy release ejector to suck the superheated CO2 gas flow at 3.5 to 4.4 MPa from the refrigeration evaporator and mixes with it to be pressurized into a gas-liquid two-phase flow and returns to the CO2 spherical tank for storage. Thus, the process of the energy storage medium doing work through the expander to release energy, and then sucking and pressurizing the CO2 of the refrigeration evaporation through the ejector is completed; after the energy storage tank finishes energy release and transfers to the waiting-for-charging stage, on the premise that the liquid volume ratio in the CO2 spherical tank is greater than 10% of the total volume, the liquid CO2 is pressurized by the pressure pump and heated through the waste heat recovery to the required density and temperature, and then through the main energy storage medium input pipe, it is filled from the bottom inlet valve of the tank and then this valve is closed to dynamically transfer it to the waiting-for-energy-storage stage for cycling; During the refrigeration-energy storage coupling and refrigeration-energy release coupling cycle stages, the CO2 evaporator absorbs the heat enthalpy of the incoming ambient air, with an evaporation pressure of 3.5 - 4.4 MPa and an evaporation temperature of 1 - 9 °C, thereby modulating the temperature and humidity of the 22 °C comfortable air-conditioning cool air or providing a 4 - 5 °C cold water cycle for utility engineering.

2. An isochoric hot-pressed CO2 energy storage and air-conditioning integrated cycle system and method according to claim 1, characterized in that Add an air-conditioning heater A, an air-conditioning heater B, and a gas-liquid separator at the outlet of the air-conditioning ejector for use in the heating and energy storage / energy release coupling cycle. In the heating-energy storage coupling cycle stage, 30-40% of the CO2 gas evaporated at a pressure of not less than 0.8MPa by absorbing heat from the ambient air intake of not less than -40℃ and directly enters the primary air intake of the two-stage air-intake air-conditioning compressor, and the remaining 60-70% is pre-pressurized by 0.2-0.4MPa through the air-conditioning ejector with an ejection coefficient of 0.2-0.6, and then enters the secondary air intake of the compressor after being defogged by the gas-liquid separator. After transcritical compression to a temperature and pressure not exceeding 250℃ / 40MPa, it sequentially releases heat through the built-in heat exchangers of all the storage tanks in the dynamic energy storage combination of no more than 18 storage tanks, so that the energy storage medium of 6-6.7MPa / 22-27℃ in the tank absorbs heat at the same volume, increases the temperature and pressure, and makes the head tank reach no more than 220℃ / 80MPa / 860kJ‧kg one by one. -3 The supercritical energy storage parameters are as follows: the transcritical compressed CO2 releases heat tank by tank until the outlet of the heat exchanger in the tail tank cools down to no less than 40°C, enters the air conditioning heater A to continue to release heat and further cool down to 5°C higher than the ambient air temperature, then enters the air conditioning expander to release isentropic work of no less than 20kJ / kg, and then attracts the low-pressure CO2 steam of the evaporator through the supersonic jet of the air conditioning ejector and mixes with it to increase the pressure to 0.2~0.4MPa higher than the evaporation pressure. After entering the gas-liquid separator for separation, the gas enters the secondary intake duct of the compressor for pressurization cycle, and the liquid enters the evaporator through the throttle valve for heat absorption and vaporization cycle, thus forming a heating-energy storage coupling cycle, and the ambient air is heated to above 20°C through the air conditioning heater A for air supply; During the heating - energy release coupling cycle, the temperature and pressure of the CO2 energy storage medium in all storage tanks in the energy release combination do not exceed 220°C / 80 MPa. After converging into the main pipe and entering the expander to release energy and do work, the outlet pressure is 6.3 - 6.8 MPa and the temperature is 28 - 65°C. It continues to release heat, cool down, and condense through the air - conditioner heater B and then directly enters the CO2 spherical tank; during this cycle stage, the Machine output expansion work decreases as the pressure and density of the energy storage medium CO2 decrease, and the weighted average value of the energy storage medium density is 70 - 100 kJ / kg; when the Machine inlet medium pressure drops to less than 8.5 MPa, the heating - energy release stage of this group of storage tanks ends. Close the outlet stop valve 1 at the top of each storage tank to dynamically transfer it to the waiting - filling stage, and use the liquid CO2 in the spherical tank to fill each of them one by one through a pressure - boosting pump, thus forming a heating - energy release coupling cycle. The air inlet of the air conditioner is heated to above 20°C through the air - conditioner heater B for air supply.

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