A supercritical carbon dioxide-based combined power and refrigeration system

Abstract

The application discloses a supercritical carbon dioxide power refrigeration combined system, and relates to the technical fields of power generation and refrigeration. The system comprises a heater, a turbine, an air inlet adjusting valve, a high-temperature supercritical carbon dioxide storage device, an air outlet adjusting valve, a high-temperature regenerator, a low-temperature regenerator, a cooler, a shunt tee valve, a main compressor, a re-compressor, a confluence tee valve, a refrigeration compressor, an intermediate heat exchanger, a throttle valve and an evaporator. The supercritical carbon dioxide power generation cycle and the transcritical carbon dioxide refrigeration cycle are highly integrated. The main compressor, the re-compressor and the generator are all driven by the mechanical energy output by the turbine. The system can fully utilize the waste heat of the refrigeration compression, effectively improve the energy conversion efficiency and flexibly switch to the refrigeration, power generation and cold and power combined supply modes.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation and refrigeration, and more particularly to a combined power generation and refrigeration system based on supercritical carbon dioxide. Background Art

[0002] The proportion of electricity consumed by cooling is increasing year by year. Therefore, efficient, flexible and adjustable combined cooling and power systems have received widespread attention.

[0003] The supercritical CO2 Brayton cycle is a power cycle based on the Brayton cycle and uses supercritical CO2 as the working fluid. By leveraging its high density, heat transfer properties, and unique physical properties near the critical region, it can significantly reduce compressor power consumption and improve cycle thermal efficiency, making it one of the most promising thermal power generation cycles of the future. Furthermore, as a natural working fluid, CO2 has a zero ODP value, a negligible GWP value, excellent stability, low price, abundant natural reserves, high density, large specific heat and volumetric cooling capacity, high latent heat and thermal conductivity, and no recovery issues. Therefore, CO2-based refrigeration systems are considered one of the most ideal refrigeration methods.

[0004] In summary, how to integrate the supercritical carbon dioxide power generation cycle and the carbon dioxide-based refrigeration cycle to make the combined cooling and power system compact and efficient, and flexible and adjustable according to external load changes, is an urgent problem that needs to be solved by technical personnel in this field. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a combined power generation and refrigeration system based on supercritical carbon dioxide, which can make full use of the waste heat of refrigeration compression, effectively improve the energy conversion efficiency, flexibly switch between refrigeration, power generation and combined cooling and power supply modes, and flexibly adjust the power generation and refrigeration capacity according to actual load requirements to meet different refrigeration temperature requirements.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A combined power generation and refrigeration system based on supercritical carbon dioxide comprises: a heater, a turbine, a high-temperature regenerator, a low-temperature regenerator, a cooler, a main compressor, a recompressor, a refrigeration compressor, a throttle valve, and an evaporator, wherein the heater, the turbine, the high-temperature regenerator, the low-temperature regenerator, the cooler, the main compressor, the recompressor, the low-temperature regenerator, the high-temperature regenerator, and the heater are sequentially connected to form a supercritical carbon dioxide power generation cycle, and the refrigeration compressor, the cooler, the throttle valve, the evaporator, and the refrigeration compressor are sequentially connected to form a transcritical carbon dioxide refrigeration cycle.

[0008] The inlet of the turbine is connected to the outlet of the heater; the hot side inlet of the high-temperature regenerator is connected to the outlet of the turbine; the hot side inlet of the low-temperature regenerator is connected to the hot side outlet of the high-temperature regenerator; the hot side inlet of the cooler is connected to the hot side outlet of the low-temperature regenerator, the inlet of the recompressor is connected to the outlet of the refrigeration compressor; the inlet of the main compressor and the inlet of the throttle valve are both connected to the hot side outlet of the cooler; the outlet of the throttle valve is connected to the hot side inlet of the evaporator; the hot side outlet of the evaporator is connected to the inlet of the refrigeration compressor; the outlet of the main compressor is connected to the cold side inlet of the low-temperature regenerator; the outlet of the recompressor and the cold side outlet of the low-temperature regenerator are both connected to the cold side inlet of the high-temperature regenerator; the cold side outlet of the high-temperature regenerator is connected to the inlet of the heater;

[0009] The main compressor, the re-compressor and the generator are all driven by the mechanical energy output by the turbine. The generator generates electrical energy to supply the electricity user. The refrigeration compressor is driven by the mechanical energy output by the turbine. The evaporator is used to cool the fluid supplied to the cold energy user.

[0010] Preferably, an intermediate heat exchanger is further included, wherein the hot side outlet of the cooler and the inlet of the main compressor are both connected to the hot side inlet of the intermediate heat exchanger, the hot side outlet of the intermediate heat exchanger is connected to the throttle valve inlet, the cold side inlet of the intermediate heat exchanger is connected to the cold side outlet of the evaporator, and the cold side outlet of the intermediate heat exchanger is connected to the inlet of the refrigeration compressor.

[0011] Preferably, a diverter three-way valve is further included, which is used to control the flow of carbon dioxide flowing to the intermediate regenerator and the main compressor. The inlet of the diverter three-way valve is connected to the hot side outlet of the cooler, and the inlet of the main compressor and the hot side inlet of the intermediate regenerator are respectively connected to the two outlets of the diverter three-way valve.

[0012] Preferably, a converging three-way valve is further included, which is used to control the flow of carbon dioxide from the hot side outlet of the low-temperature regenerator to the recompressor, and the outlet of the refrigeration compressor, the hot side outlet of the low-temperature regenerator and the hot side inlet of the cooler are all connected to the inlet of the converging three-way valve, and the outlet of the converging three-way valve is connected to the inlet of the recompressor.

[0013] Preferably, a high-temperature supercritical carbon dioxide storage device is further included, wherein control valves are provided at the inlet and outlet of the high-temperature supercritical carbon dioxide storage device, the cold side outlet of the high-temperature regenerator and the inlet of the heater are both connected to the inlet of the high-temperature supercritical carbon dioxide storage device, and the outlet of the turbine and the hot side inlet of the high-temperature regenerator are both connected to the outlet of the high-temperature supercritical carbon dioxide storage device.

[0014] Preferably, the turbine, the generator, the main compressor, the re-compressor and the refrigeration compressor are coaxially connected via a speed regulating clutch device so that the rotational speed of each impeller machine can be adjusted.

[0015] Preferably, the heat source absorbed by the heater includes a nuclear reactor in a nuclear power plant, a boiler in a coal-fired power plant, a collector in a solar power plant, a geothermal source in a geothermal power plant, a gas turbine exhaust in a gas turbine power generation system, or industrial waste heat.

[0016] When using the supercritical carbon dioxide-based combined power generation and refrigeration system provided by the present invention, a supercritical carbon dioxide power generation cycle and a transcritical carbon dioxide refrigeration cycle are highly integrated. The supercritical carbon dioxide power generation cycle includes a heater, a turbine, a high-temperature regenerator, a low-temperature regenerator, a cooler, a main compressor, and a recompressor, with carbon dioxide as the circulating working fluid. The transcritical carbon dioxide refrigeration cycle includes a refrigeration compressor, a cooler, an intermediate regenerator, a throttle valve, and an evaporator, with carbon dioxide as the refrigerant. The supercritical carbon dioxide power generation cycle and the transcritical carbon dioxide refrigeration cycle share a cooler. The compressed working fluid of the transcritical carbon dioxide refrigeration cycle is merged into the working working fluid, participating in the power generation cycle, and the waste heat from the refrigeration compression is utilized.

[0017] Furthermore, the transcritical CO2 refrigeration cycle is driven by a supercritical CO2 power generation cycle, eliminating the need for additional high-grade electricity. The mechanical speed of each impeller is adjustable, and in full power generation mode, the refrigeration compressor can be disconnected from the turbine. The working fluid in the refrigeration cycle is CO2, and the temperature of liquid CO2 can be lowered to below 0°C. By adjusting the throttle valve pressure drop and the CO2 evaporation temperature, the system can meet diverse cooling needs, such as air conditioning, food preservation, and refrigeration.

[0018] In summary, the supercritical carbon dioxide-based combined power generation and refrigeration system provided by the present invention can fully utilize the waste heat of refrigeration compression, effectively improve energy conversion efficiency, flexibly switch between refrigeration, power generation and combined cooling and power supply modes, and flexibly adjust the power generation and refrigeration capacity according to actual load requirements to meet different refrigeration temperature requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0020] Figure 1 This is a schematic structural diagram of the supercritical carbon dioxide-based power generation and refrigeration combined system provided by the present invention.

[0021] Figure 1 middle:

[0022] 1 is the generator, 2 is the turbine, 3 is the heater, 4 is the high-temperature regenerator, 5 is the low-temperature regenerator, 6 is the cooler, 7 is the cold energy user, 8 is the evaporator, 9 is the throttle valve, 10 is the intermediate regenerator, 11 is the refrigeration compressor, 12 is the main compressor, 13 is the recompressor, 14 is the electric energy user, 15 is the diversion three-way valve, 16 is the converging three-way valve, and 17 is the high-temperature supercritical carbon dioxide storage device. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The core of the present invention is to provide a combined power generation and refrigeration system based on supercritical carbon dioxide, which can make full use of the waste heat of refrigeration compression, effectively improve energy conversion efficiency, flexibly switch between refrigeration, power generation and combined cooling and power supply modes, and flexibly adjust the power generation and cooling capacity according to actual load requirements to meet different refrigeration temperature requirements.

[0025] Please refer to Figure 1 , Figure 1 This is a schematic structural diagram of the supercritical carbon dioxide-based power generation and refrigeration combined system provided by the present invention.

[0026] This specific embodiment provides a combined power generation and refrigeration system based on supercritical carbon dioxide, including: a heater 3, a turbine 2, a high-temperature regenerator 4, a low-temperature regenerator 5, a cooler 6, a main compressor 12, a recompressor 13, a refrigeration compressor 11, a throttle valve 9, and an evaporator 8. The heater 3, turbine 2, high-temperature regenerator 4, low-temperature regenerator 5, cooler 6, main compressor 12, recompressor 13, low-temperature regenerator 5, high-temperature regenerator 4, and heater 3 are sequentially connected to form a supercritical carbon dioxide power generation cycle, and the refrigeration compressor 11, cooler 6, throttle valve 9, evaporator 8, and refrigeration compressor 11 are sequentially connected to form a transcritical carbon dioxide refrigeration cycle.

[0027] The inlet of the turbine 2 is connected to the outlet of the heater 3; the hot side inlet of the high-temperature regenerator 4 is connected to the outlet of the turbine 2; the hot side inlet of the low-temperature regenerator 5 is connected to the hot side outlet of the high-temperature regenerator 4; the hot side inlet of the cooler 6 is connected to the hot side outlet of the low-temperature regenerator 5, and the inlet of the recompressor 13 is connected to the outlet of the refrigeration compressor 11; the inlet of the main compressor 12 and the inlet of the throttle valve 9 are both connected to the hot side outlet of the cooler 6; the outlet of the throttle valve 9 is connected to the hot side inlet of the evaporator 8; the hot side outlet of the evaporator 8 is connected to the inlet of the refrigeration compressor 11; the outlet of the main compressor 12 is connected to the cold side inlet of the low-temperature regenerator 5; the outlet of the recompressor 13 and the cold side outlet of the low-temperature regenerator 5 are both connected to the cold side inlet of the high-temperature regenerator 4; the cold side outlet of the high-temperature regenerator 4 is connected to the inlet of the heater 3.

[0028] The main compressor 12, the re-compressor 13 and the generator 1 are all driven by the mechanical energy output by the turbine 2. The generator 1 generates electrical energy to supply the electricity user 14. The refrigeration compressor 11 is driven by the mechanical energy output by the turbine 2. The evaporator 8 is used to cool the fluid supplied to the cold energy user 7.

[0029] It should be noted that the carbon dioxide in the heater 3 absorbs heat from the heat source and heats up. The high-temperature and high-pressure airflow enters the turbine 2 and expands and performs work in the turbine 2, converting the thermal energy of the supercritical carbon dioxide into mechanical energy of the rotating turbine 2, which is used to drive the main compressor 12, the re-compressor 13 and the refrigeration compressor 11 to compress the carbon dioxide, and is used to drive the coaxially connected generator 1 to generate electricity. The power generated by the generator 1 is supplied to the electricity user 14; the carbon dioxide expanded through the turbine 2 flows through the high-temperature regenerator 4 and the low-temperature regenerator 5 in sequence and releases heat to preheat the compressed carbon dioxide.

[0030] After releasing heat through the two regenerators, the carbon dioxide is divided into two parts: one part directly enters the re-compressor 13 for compression; the other part enters the cooler 6 to further release heat and is cooled to a temperature close to the critical point. In addition, the carbon dioxide cooled by the cooler 6 is divided into two parts: one part of the carbon dioxide gas flow enters the main compressor 12 for pressurization. Since the temperature is cooled to near the critical point of carbon dioxide, the power consumption is reduced, and then it enters the low-temperature regenerator 5 to recover the heat of the exhaust gas of turbine 2; the other part of the carbon dioxide flows to the throttle valve 9, where it is throttled, cooled and pressure-reduced to the evaporation temperature, and then enters the evaporator 8 to absorb heat and evaporate into gas, thereby utilizing the latent heat of evaporation of liquid carbon dioxide for refrigeration. After the fluid on the other side of the evaporator 8 is cooled, it is supplied to users who need cold energy. The temperature of the liquid carbon dioxide can be reduced to below 0 degrees Celsius. By adjusting the throttle valve 9 to reduce the pressure, Changing the evaporation temperature of carbon dioxide can meet different refrigeration needs, such as food preservation, refrigeration and air conditioning; the carbon dioxide after evaporation and heat absorption enters the refrigeration compressor 11 for pressurization; the pressurized carbon dioxide is mixed with part of the hot side outlet air flow of the low-temperature regenerator 5 and then enters the re-compressor 13 for pressurization, making full use of the waste heat of refrigeration compression; the carbon dioxide compressed by the re-compressor 13 is merged into the cold side outlet air flow of the low-temperature regenerator 5, and then flows through the high-temperature regenerator 4 to further recover the heat of the high-temperature turbine 2 exhaust gas, so that the temperature is further increased; finally, the carbon dioxide gas flow returns to the heater 3 to complete a complete supercritical carbon dioxide power generation and refrigeration combined cycle.

[0031] It should also be noted that the combined supercritical CO2 power generation and refrigeration system highly integrates the supercritical CO2 power generation cycle and the transcritical CO2 refrigeration cycle. The supercritical CO2 power generation cycle includes a heater 3, a turbine 2, a generator 1, a high-temperature regenerator 4, a low-temperature regenerator 5, a cooler 6, a main compressor 12, and a recompressor 13, with CO2 as the circulating working fluid. The transcritical CO2 refrigeration cycle includes a refrigeration compressor 11, a cooler 6, a throttle valve 9, and an evaporator 8, with CO2 as the refrigerant. Furthermore, the supercritical CO2 power generation cycle and the transcritical CO2 refrigeration cycle share the cooler 6, and the compressed working fluid of the refrigeration subsystem is merged into the recompressed working fluid of the power generation subsystem, participating in the diversion and recompression process of the power generation subsystem.

[0032] Through the above-mentioned arrangement, the structure of the supercritical carbon dioxide power generation and refrigeration combined system is made compact; at the same time, the supercritical carbon dioxide power generation subsystem can make full use of the waste heat of refrigeration compression, reducing the cold source loss of the refrigeration subsystem; and the compressed working fluid of the refrigeration subsystem participates in the diversion and recompression process of the power generation subsystem, which can reduce the temperature mismatch between the hot side and cold side fluids in the regenerator, reduce the irreversible loss in the regenerator, and improve the cycle efficiency.

[0033] Furthermore, the refrigeration subsystem is driven by the power generation subsystem, eliminating the need for additional high-grade electricity. The working fluid in the refrigeration cycle is carbon dioxide, and the temperature of liquid carbon dioxide can be reduced to below 0 degrees Celsius. By adjusting the pressure drop across the throttle valve 9, the carbon dioxide evaporation temperature can be adjusted to meet various refrigeration needs, such as air conditioning, food preservation, and refrigeration. Therefore, the supercritical carbon dioxide-based power generation and refrigeration combined system provided by the present invention can fully recycle waste heat from refrigeration compression, effectively improving energy conversion efficiency and meeting various refrigeration temperature requirements.

[0034] On the basis of the above embodiment, preferably, an intermediate heat regenerator 10 is further included, the hot side outlet of the cooler 6 and the inlet of the main compressor 12 are both connected to the hot side inlet of the intermediate heat regenerator 10, the hot side outlet of the intermediate heat regenerator 10 is connected to the inlet of the throttle valve 9, the cold side inlet of the intermediate heat regenerator 10 is connected to the cold side outlet of the evaporator 8, and the cold side outlet of the intermediate heat regenerator 10 is connected to the inlet of the refrigeration compressor 11.

[0035] It should be noted that the intermediate heat regenerator 10 can be set between the hot side outlet of the cooler 6 and the inlet of the throttle valve 9. After the carbon dioxide is cooled by the cooler 6, it is further cooled in the intermediate heat regenerator 10, thereby reducing the irreversible loss of carbon dioxide in the process of throttling, cooling and reducing pressure by the throttle valve 9, improving the efficiency of the refrigeration cycle, and thus improving the cycle efficiency of the system.

[0036] Preferably, a diverter three-way valve 15 is further included, which is used to control the flow of carbon dioxide flowing to the intermediate heat regenerator 10 and the main compressor 12. The inlet of the diverter three-way valve 15 is connected to the hot side outlet of the cooler 6, and the inlet of the main compressor 12 and the hot side inlet of the intermediate heat regenerator 10 are respectively connected to the two outlets of the diverter three-way valve 15.

[0037] It should be noted that the diverter three-way valve 15 can control the flow of carbon dioxide flowing to the intermediate heat regenerator 10 and the main compressor 12, that is, by controlling the flow of carbon dioxide flowing to the refrigeration subsystem, the cooling capacity can be adjusted according to the external load. In addition, the refrigeration subsystem can also be shut down and switched to full power generation mode, combined cooling and power mode, and full refrigeration mode.

[0038] Preferably, a converging three-way valve 16 is also included, which is used to control the flow of carbon dioxide from the hot side outlet of the low-temperature regenerator 5 to the re-compressor 13. The outlet of the refrigeration compressor 11, the hot side outlet of the low-temperature regenerator 5, and the hot side inlet of the cooler 6 are all connected to the inlet of the converging three-way valve 16, and the outlet of the converging three-way valve 16 is connected to the inlet of the re-compressor 13.

[0039] It should be noted that the converging three-way valve 16 controls the flow of carbon dioxide directly from the hot-side outlet of the low-temperature regenerator 5 to the recompressor 13. This allows the split ratio of the power generation subsystem to be adjusted according to changes in the external load, minimizing the mismatch in fluid temperature between the two sides of the regenerator, thereby reducing irreversible losses in the regenerator and maintaining high system efficiency. Simultaneously, the converging three-way valve 16 can coordinate with the diverting three-way valve 15 to control the flow of the refrigeration subsystem, adjusting the cooling capacity based on the external cooling load demand, and flexibly switching between full power generation mode, combined cooling and power mode, and full cooling mode according to actual needs.

[0040] Preferably, a high-temperature supercritical carbon dioxide storage device 17 is further included, and control valves are provided at the inlet and outlet of the high-temperature supercritical carbon dioxide storage device 17. The cold side outlet of the high-temperature regenerator 4 and the inlet of the heater 3 are both connected to the inlet of the high-temperature supercritical carbon dioxide storage device 17, and the outlet of the turbine 2 and the hot side inlet of the high-temperature regenerator 4 are both connected to the outlet of the high-temperature supercritical carbon dioxide storage device 17.

[0041] It should be noted that the high-temperature supercritical carbon dioxide storage device 17 can adjust the carbon dioxide mass flow rate of the entire system based on changes in external load through the control valves at its inlet and outlet under the influence of pressure differentials. Specifically, when external load demand decreases, the control valve at the inlet of the high-temperature supercritical carbon dioxide storage device 17 is opened under the control of the electronic control device, and carbon dioxide at the hot-side outlet of the high-temperature regenerator 4 enters the high-temperature supercritical carbon dioxide storage device 17 under the influence of the pressure differential, thereby reducing the carbon dioxide flow rate in the cycle and reducing the power generation and cooling capacity of the cycle. Conversely, when external load demand increases, the control valve at the outlet of the high-temperature supercritical carbon dioxide storage device 17 is opened under the control of the electronic control device, and carbon dioxide flows out of the high-temperature supercritical carbon dioxide storage device 17 under the influence of the pressure differential and merges into the exhaust gas of the turbine 2, thereby increasing the carbon dioxide flow rate in the cycle and increasing the power generation and cooling capacity of the cycle. Therefore, this system can adjust power generation and cooling capacity based on changes in external load to meet different power generation and cooling load demands.

[0042] Preferably, the turbine 2, generator 1, main compressor 13, recompressor 12, and refrigeration compressor 11 are coaxially connected via a speed-regulating clutch device, enabling adjustable speeds of the various impeller machines. This arrangement effectively improves the system's structural compactness, and the speeds of the various impeller machines are adjustable. In the full power generation mode, the refrigeration compressor 11 can be disconnected.

[0043] Of course, the coaxial connection of the turbine 2, generator 1, main compressor 12, re-compressor 13 and refrigeration compressor 11 is only a preferred embodiment, not the only embodiment, that is, a transmission device can also be used to connect the turbine 2, generator 1, main compressor 12, re-compressor 13 and refrigeration compressor 11 non-coaxially.

[0044] Preferably, the heat source absorbed by heater 3 includes a nuclear reactor in a nuclear power plant, a boiler in a coal-fired power plant, a collector in a solar power plant, a geothermal source in a geothermal power plant, exhaust gas from a gas turbine power generation system, or industrial waste heat. This means that the system is applicable to a wide variety of heat sources and has good application prospects.

[0045] In order to further illustrate the supercritical carbon dioxide-based combined power generation and refrigeration system provided by the present invention, the above-mentioned features will be described below.

[0046] The supercritical carbon dioxide-based combined power generation and refrigeration system provided in this embodiment of the present invention highly integrates a supercritical carbon dioxide power generation cycle and a transcritical carbon dioxide refrigeration cycle. The supercritical carbon dioxide power generation cycle includes a heater 3, a turbine 2, a high-temperature supercritical carbon dioxide storage device 17, a generator 1, a high-temperature regenerator 4, a low-temperature regenerator 5, a converging three-way valve 16, a cooler 6, a diverting three-way valve 15, a main compressor 12, and a recompressor 13. The circulating working fluid is carbon dioxide.

[0047] The transcritical CO2 refrigeration cycle includes a refrigeration compressor 11, a converging three-way valve 16, a cooler 6, a diverting three-way valve 15, an intermediate heat regenerator 10, a throttle valve 9, and an evaporator 8. The refrigerant is CO2. The supercritical CO2 power generation cycle absorbs high-temperature heat through a heater 3. The transcritical CO2 refrigeration cycle and the supercritical CO2 power generation cycle share a cooler 6 and are integrated via a diverting three-way valve 15 and a converging three-way valve 16. The compressed working fluid of the transcritical CO2 refrigeration cycle is merged into the working working fluid, participating in the power generation cycle, and the waste heat from the refrigeration compression is utilized.

[0048] Through the above-mentioned arrangement, the structure of the supercritical carbon dioxide power generation and refrigeration combined system is made compact; at the same time, the supercritical carbon dioxide power generation subsystem can fully utilize the waste heat of refrigeration compression, reducing the cold source loss of the refrigeration subsystem; and, the compressed working fluid of the refrigeration subsystem participates in the diversion and recompression process of the power generation subsystem, which can reduce the temperature mismatch between the hot side and cold side fluids in the regenerator, reduce the irreversible loss in the regenerator, and improve the cycle efficiency.

[0049] In addition, the refrigeration subsystem is driven by the power generation subsystem, eliminating the need for additional high-grade electricity. Furthermore, the working fluid in the refrigeration cycle is carbon dioxide, and the temperature of liquid carbon dioxide can be reduced to below 0 degrees Celsius. By adjusting the pressure drop of the throttle valve 9 and changing the carbon dioxide evaporation temperature, different refrigeration needs can be met, such as air conditioning, food preservation, and refrigeration. The diverter three-way valve 15 and the converging three-way valve 16 can control the carbon dioxide flow to the refrigeration subsystem according to external load requirements, adjust the cooling capacity, and flexibly switch between full power generation mode, combined cooling and power generation mode, and full cooling mode according to actual needs. At the same time, the diverter ratio of the power generation subsystem can be adjusted to reduce irreversible losses in the regenerator and maintain high system efficiency. Furthermore, the high-temperature supercritical carbon dioxide storage device 17 can adjust the carbon dioxide mass flow of the entire system according to changes in external loads through the pressure differential of the inlet and outlet control valves, thereby meeting different power generation and cooling load requirements. Therefore, this system can fully utilize the waste heat from refrigeration compression, effectively improve energy conversion efficiency, flexibly switch between cooling, power generation, and combined cooling and power generation modes, and flexibly adjust power generation and cooling capacity according to actual load requirements to meet different cooling temperature requirements.

[0050] The specific implementation scheme of the present invention is as follows: the heat carrier transfers heat to the supercritical carbon dioxide circulating medium in the heater 3, causing it to heat up to the highest temperature of the cycle. The heated carbon dioxide enters the turbine 2 and expands in the turbine 2 to perform work, converting the thermal energy of the supercritical carbon dioxide into mechanical energy, which is used to drive the main compressor 12, the recompressor 13 and the refrigeration compressor 11 to compress the carbon dioxide flow. At the same time, the generator 1 is driven to generate electricity to provide electricity to the power user 14; the carbon dioxide expanded by the turbine 2 flows through the high-temperature regenerator 4 and the low-temperature regenerator 5 in sequence, and releases heat therein to preheat the compressed carbon dioxide; the carbon dioxide after releasing heat is divided into two air flows, one of which flows to the converging three-way valve 16, while the other flows through the cooler 6 and is cooled to near the critical point temperature; the cooled carbon dioxide air flow is divided into two air flows again through the diverter three-way valve 15, one of which enters the main compressor 12 for supercharging. Since the temperature is cooled to near the critical point of carbon dioxide, the power consumption of the main compressor 12 is reduced, and the high pressure obtained is obtained. The airflow passes through the low-temperature regenerator 5, absorbing heat from the exhaust gas from turbine 2. Meanwhile, another stream of carbon dioxide, separated by the diverting three-way valve 15, flows to the intermediate regenerator 10, where it is further cooled to a liquid state. The cooled carbon dioxide passes through the throttle valve 9, where it is throttled and reduced in temperature and pressure, further lowering its temperature to the evaporation temperature. It then enters the evaporator 8, where it absorbs heat and evaporates into gas, thereby utilizing the latent heat of evaporation of the liquid carbon dioxide for refrigeration. The fluid on the other side of the evaporator 8 is cooled and supplied to users requiring cold energy. The evaporated carbon dioxide flows to the other side of the intermediate heat exchanger 10, where it absorbs heat and then enters the refrigeration compressor 11 for pressurization. The pressurized carbon dioxide enters the converging three-way valve 16, merges with the other stream of carbon dioxide entering the converging three-way valve 16, and then enters the recompressor 13 for further pressurization. It then merges with the cold-side outlet airflow of the low-temperature regenerator 5 before flowing to the high-temperature regenerator 4 to further absorb heat from the exhaust gas. Finally, the airflow returns to the heater 3, forming a complete supercritical carbon dioxide-based power generation and refrigeration system.

[0051] In addition, when the external load changes, the control valves at the inlet and outlet of the diverter three-way valve 15, the converging three-way valve 16, and the high-temperature supercritical carbon dioxide storage device 17 can be adjusted to adjust the cooling capacity and power generation or switch between different power generation and cooling modes. For example, when cooling is not required, the valves connecting the diverter three-way valve 15 and the converging three-way valve 16 to the cooling side can be closed to prevent carbon dioxide from flowing to the cooling subsystem. At the same time, the cooling compressor is disconnected from the generator set. At this time, the system no longer provides cooling energy and is in a full power generation mode. When power is not required, the valve connecting the converging three-way valve 16 to the power generation side can be closed, and the valve connecting the diverter three-way valve 15 to the power generation side can be reduced or even closed to allow most or all of the air flow to flow to the cooling subsystem. The output power of turbine 2 is all used to drive the compressor. At this time, the system no longer provides power and is in a full cooling mode. When both cooling energy and power are required, the diverter three-way valve 15 and the converging three-way valve 16 can be adjusted according to changes in the external cooling load demand to control the flow of carbon dioxide to the cooling subsystem, thereby achieving flexible regulation of cooling capacity.

[0052] Furthermore, in the full power generation mode, full refrigeration or combined cooling and power generation mode, when the overall external load demand decreases, the control valve at the inlet of the high-temperature supercritical carbon dioxide storage device 17 can be opened to allow the circulating working fluid to flow into the high-temperature supercritical carbon dioxide storage device 17 under the action of the pressure difference, thereby reducing the circulating working fluid flow rate, and at the same time adjusting the impeller mechanical speed to reduce the provided cooling capacity or power generation; and when the overall external load demand increases, the control valve at the outlet of the high-temperature supercritical carbon dioxide storage device 17 can be opened to allow the carbon dioxide inside the high-temperature supercritical carbon dioxide storage device 17 to flow out of the high-temperature supercritical carbon dioxide storage device 17 under the action of the pressure difference and merge with the circulating working fluid, thereby increasing the circulating working fluid flow rate, and at the same time adjusting the impeller mechanical speed to increase the provided cooling capacity or power generation.

[0053] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. Any combination of all the embodiments provided by the present invention is within the scope of protection of this invention and will not be described in detail here.

[0054] The above is a detailed introduction to the supercritical carbon dioxide-based power generation and refrigeration combined system provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A combined power generation and refrigeration system based on supercritical carbon dioxide, characterized in that: include: A heater (3), a turbine (2), a high-temperature regenerator (4), a low-temperature regenerator (5), a cooler (6), a main compressor (12), a recompressor (13), a refrigeration compressor (11), a throttle valve (9) and an evaporator (8); the heater (3), the turbine (2), the high-temperature regenerator (4), the low-temperature regenerator (5), the cooler (6), the main compressor (12), the recompressor (13), the low-temperature regenerator (5), the high-temperature regenerator (4) and the heater (3) are sequentially connected to form a supercritical carbon dioxide power generation cycle; the refrigeration compressor (11), the cooler (6), the throttle valve (9), the evaporator (8) and the refrigeration compressor (11) are sequentially connected to form a transcritical carbon dioxide refrigeration cycle; The inlet of the turbine (2) is connected to the outlet of the heater (3); the hot side inlet of the high-temperature regenerator (4) is connected to the outlet of the turbine (2); the hot side inlet of the low-temperature regenerator (5) is connected to the hot side outlet of the high-temperature regenerator (4); the hot side inlet of the cooler (6) is connected to the hot side outlet of the low-temperature regenerator (5), the inlet of the recompressor (13) is connected to the outlet of the refrigeration compressor (11); the inlet of the main compressor (12) and the inlet of the throttle valve (9) are both connected to the cooling The outlet of the throttle valve (9) is connected to the hot side inlet of the evaporator (8); the hot side outlet of the evaporator (8) is connected to the inlet of the refrigeration compressor (11); the outlet of the main compressor (12) is connected to the cold side inlet of the low-temperature regenerator (5); the outlet of the recompressor (13) and the cold side outlet of the low-temperature regenerator (5) are both connected to the cold side inlet of the high-temperature regenerator (4); the cold side outlet of the high-temperature regenerator (4) is connected to the inlet of the heater (3); The main compressor (12), the recompressor (13) and the generator (1) are all driven by the mechanical energy output by the turbine (2); the generator (1) generates electric energy and supplies it to the electric energy user (14); the refrigeration compressor (11) is driven by the mechanical energy output by the turbine (2); and the evaporator (8) is used to cool the fluid supplied to the cold energy user (7); The turbine (2), the generator (1), the main compressor (12), the recompressor (13) and the refrigeration compressor (11) are coaxially connected via a speed control clutch device so that the rotational speed of each impeller machine can be adjusted; the heat source absorbed by the heater (3) includes a nuclear reactor of a nuclear power plant, a boiler of a coal-fired power plant, a collector of a solar power plant, a geothermal source of a geothermal power plant, a gas turbine exhaust of a gas turbine power generation system, or industrial waste heat.

2. The supercritical carbon dioxide-based power generation and refrigeration combined system according to claim 1 is characterized in that: It also includes an intermediate heat exchanger (10), the hot side outlet of the cooler (6) and the inlet of the main compressor (12) are both connected to the hot side inlet of the intermediate heat exchanger (10), the hot side outlet of the intermediate heat exchanger (10) is connected to the inlet of the throttle valve (9), the cold side inlet of the intermediate heat exchanger (10) is connected to the cold side outlet of the evaporator (8), and the cold side outlet of the intermediate heat exchanger (10) is connected to the inlet of the refrigeration compressor (11).

3. The supercritical carbon dioxide-based power generation and refrigeration combined system according to claim 2, characterized in that: The system further comprises a diverter three-way valve (15), wherein the diverter three-way valve (15) is used to control the flow of carbon dioxide to the intermediate heat regenerator (10) and the main compressor (12), wherein the inlet of the diverter three-way valve (15) is connected to the hot side outlet of the cooler (6), and the inlet of the main compressor (12) and the hot side inlet of the intermediate heat regenerator (10) are respectively connected to the two outlets of the diverter three-way valve (15).

4. The supercritical carbon dioxide-based power generation and refrigeration combined system according to claim 1 is characterized in that: It also includes a converging three-way valve (16), which is used to control the flow of carbon dioxide from the hot side outlet of the low-temperature regenerator (5) to the recompressor (13), the outlet of the refrigeration compressor (11), the hot side outlet of the low-temperature regenerator (5), and the hot side inlet of the cooler (6) are all connected to the inlet of the converging three-way valve (16), and the outlet of the converging three-way valve (16) is connected to the inlet of the recompressor (13).

5. The supercritical carbon dioxide-based power generation and refrigeration combined system according to claim 1 is characterized in that: It also includes a high-temperature supercritical carbon dioxide storage device (17), wherein the inlet and outlet of the high-temperature supercritical carbon dioxide storage device (17) are both provided with control valves, the cold side outlet of the high-temperature regenerator (4) and the inlet of the heater (3) are both connected to the inlet of the high-temperature supercritical carbon dioxide storage device (17), and the outlet of the turbine (2) and the hot side inlet of the high-temperature regenerator (4) are both connected to the outlet of the high-temperature supercritical carbon dioxide storage device (17).

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