A regenerative transcritical carbon dioxide two-stage compression system

Abstract

This invention discloses a regenerative transcritical carbon dioxide two-stage compression system. The system includes a storage tank, the first outlet of which is connected to the cold-side inlet of a first regenerator; the first regenerator is connected to the working fluid inlets of the second and third compressors via a first compressor and a precooler; the working fluid outlets of the second and third compressors are connected to the hot-side inlet of the second regenerator via a gas cooler; the hot-side outlet of the second regenerator is connected to the working fluid inlet of a flash tank via a first expansion valve; the cold-side outlet of the second regenerator is connected to the working fluid inlets of the second and third compressors; the cold-side inlet of the second regenerator is connected to the gas phase working fluid outlet of the flash tank; the liquid phase working fluid outlet of the flash tank is connected to the hot-side inlet of the first regenerator; the hot-side outlet of the first regenerator is connected to the first inlet of the storage tank via a second expansion valve; and the storage tank is connected to the ice rink coil via a transport pump. This invention effectively recovers energy from the low-temperature carbon dioxide working fluid by introducing a low-pressure regenerator and a high-pressure regenerator, achieving energy conservation and emission reduction.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration and ice-making system technology, specifically to industrial ice-making, cold chain transportation, and food preservation that require efficient combined cooling and heating, and particularly to a regenerative transcritical carbon dioxide two-stage compression system. Background Technology

[0002] Carbon dioxide, as a natural refrigerant, has received widespread attention in the refrigeration field in recent years due to its environmental friendliness, non-toxicity, and non-flammability. However, traditional transcritical carbon dioxide refrigeration systems suffer from the following problems: 1. Imbalance between heating and cooling efficiency: In the transcritical cycle, carbon dioxide gas is in a supercritical state in the gas cooler (the so-called supercritical state refers to the state where the temperature and pressure of a substance are higher than the critical point, and the substance no longer has the distinction between liquid and gas, but presents a uniform fluid state), resulting in low heat release efficiency and low overall system energy efficiency.

[0003] 2. High heat loss of low-temperature gas: The low-temperature gas flowing out of the low-pressure compressor outlet is usually not effectively utilized before entering the high-pressure compressor, resulting in energy waste.

[0004] Therefore, there is an urgent need to develop a technology that can solve the above-mentioned technical problems. Utility Model Content

[0005] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a regenerative transcritical two-stage carbon dioxide compression system.

[0006] Therefore, this utility model provides a regenerative transcritical carbon dioxide two-stage compression system, including a liquid storage tank, a first regenerator, a first compressor, a precooler, a second compressor, a third compressor, an air cooler, a second regenerator, a first expansion valve, a flash tank, a second expansion valve, a transport pump, and an ice rink coil. The first outlet a of the liquid storage tank is connected to the cold side inlet b of the first regenerator; The cold side outlet a of the first regenerator is connected to the working fluid inlet of the first compressor; The working fluid outlet of the first compressor is connected to the working fluid inlet of the precooler; The working fluid outlet of the precooler is connected to the working fluid inlet of the second compressor and the working fluid inlet of the third compressor, respectively; The working fluid outlets of the second compressor and the third compressor are connected to the working fluid inlet of the air cooler after they converge. The working fluid outlet of the air cooler is connected to the hot side inlet c of the second regenerator; The hot-side outlet d of the second regenerator is connected to the working fluid inlet b of the flash tank via the first expansion valve. The cold side outlet a of the second regenerator is connected to the working fluid inlet of the second compressor and the working fluid inlet of the third compressor, respectively. The cold side inlet b of the second regenerator is connected to the gaseous working fluid outlet c at the top of the flash tank. The liquid working fluid outlet a of the flash tank is connected to the hot side inlet c of the first regenerator; The hot-side outlet d of the first regenerator is connected to the first inlet b at the top of the storage tank via the second expansion valve; The second outlet c at the bottom of the storage tank is connected to the working fluid inlet of the transfer pump; The working fluid outlet of the transport pump is connected to the working fluid inlet of the ice rink coil; The working fluid outlet of the ice rink coil is connected to the second inlet d at the right end of the storage tank.

[0007] As can be seen from the technical solution provided by this utility model above, compared with the prior art, this utility model provides a regenerative transcritical carbon dioxide two-stage compression system with a scientific design. By introducing a low-pressure regenerator and a high-pressure regenerator, this utility model effectively recovers the energy of the low-temperature carbon dioxide working fluid, improves the overall energy efficiency of the system, and has significant practical significance.

[0008] Furthermore, this invention can be further combined with dynamic control strategies to optimize the system's operating status, thereby improving the overall cooling and heating energy efficiency of the carbon dioxide refrigeration system. Attached Figure Description

[0009] Figure 1 A schematic diagram of a regenerative transcritical carbon dioxide two-stage compression system provided by this utility model; Figure 2 A schematic diagram of the control process of a regenerative transcritical two-stage carbon dioxide compression system provided by this utility model in an embodiment; In the diagram, 1-liquid storage tank, 2-first regenerator (specifically a low-pressure regenerator), 3-first compressor (specifically a low-pressure stage compressor), 4-precooler, and 5-second compressor (specifically a high-pressure stage compressor). 6-Third compressor (specifically a high-pressure stage compressor), 7-Air cooler, 8-Second regenerator (specifically a high-pressure regenerator), 9-First expansion valve (specifically a high-pressure expansion valve), 10-Flash tank; 11-Second expansion valve (specifically a low-pressure expansion valve), 12-Transfer pump, 13-Ice rink coil. Detailed Implementation

[0010] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0011] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0012] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0013] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0014] See Figure 1 , Figure 2 This utility model provides a regenerative transcritical carbon dioxide two-stage compression system, including a liquid storage tank 1, a first regenerator 2, a first compressor 3, a precooler 4, a second compressor 5, a third compressor 6, an air cooler 7, a second regenerator 8, a first expansion valve 9, a flash tank 10, a second expansion valve 11, a transport pump 12, and an ice rink coil 13. The first outlet a of the liquid storage tank 1 is connected to the cold side inlet b of the first regenerator 2; The cold side outlet a of the first regenerator 2 is connected to the working fluid inlet of the first compressor 3; The working fluid outlet of the first compressor 3 is connected to the working fluid inlet of the precooler 4; The working fluid outlet of the precooler 4 is connected to the working fluid inlet of the second compressor 5 and the working fluid inlet of the third compressor 6, respectively. The working fluid outlets of the second compressor 5 and the third compressor 6 are connected to the working fluid inlet of the air cooler 7 after they converge. The working fluid outlet of the air cooler 7 is connected to the hot side inlet c of the second regenerator 8; The hot side outlet d of the second regenerator 8 is connected to the working fluid inlet b of the flash tank 10 through the first expansion valve 9. The cold side outlet a of the second regenerator 8 is connected to the working fluid inlet of the second compressor 5 and the working fluid inlet of the third compressor 6, respectively. The cold side inlet b of the second regenerator 8 is connected to the gaseous working fluid outlet c at the top of the flash tank 10. The liquid working fluid outlet a of the flash tank 10 is connected to the hot side inlet c of the first regenerator 2; The hot side outlet d of the first regenerator 2 is connected to the first inlet b at the top of the storage tank 1 through the second expansion valve 11; The second outlet c at the bottom of the storage tank 1 is connected to the working fluid inlet of the transfer pump 12; The working fluid outlet of the transport pump 12 is connected to the working fluid inlet of the ice rink coil 13; The working fluid outlet of the ice rink coil 13 is connected to the second inlet d at the right end of the liquid storage tank 1.

[0015] In this invention, carbon dioxide is used as the working fluid in the system.

[0016] In this utility model, specifically, the first compressor 3 is a low-pressure stage compressor, used to realize the pressurization and heating process of the low-pressure side carbon dioxide working fluid to form a high-temperature and high-pressure carbon dioxide working fluid. Both the second compressor 5 and the third compressor 6 are high-pressure stage compressors, used to achieve the pressurization and heating process of the carbon dioxide working fluid on the high-pressure side.

[0017] For example, compressors with an exhaust pressure below 1 MPa are low-pressure compressors; compressors with an exhaust pressure greater than 10 MPa are high-pressure compressors.

[0018] In this utility model, specifically, the first regenerator 2 is a low-pressure regenerator (a regenerator, also called a gas-liquid heat exchanger). The second regenerator 8 is specifically a high-pressure regenerator; It should be noted that the second regenerator 8, as a high-pressure regenerator, is located in front of the first expansion valve 9 (specifically a high-pressure expansion valve) in the flow path of the working fluid. The first regenerator 2 is a low-pressure regenerator, which is located in front of the first compressor 3 (i.e., the low-pressure stage compressor) in the flow path of the working fluid.

[0019] The first regenerator 2 is used to cool the working fluid entering the first compressor 3 (i.e., the low-pressure stage compressor); The second regenerator 8 is used to cool the working fluid entering the second compressor 5 and the third compressor 6 (i.e., the two high-pressure stage compressors).

[0020] In this invention, the pressure of the working fluid in the second regenerator 8 (high-pressure regenerator) is greater than the pressure of the working fluid in the first regenerator 2 (low-pressure regenerator).

[0021] In this utility model, specifically, the first expansion valve 9 is a high-pressure expansion valve; The second expansion valve 11 is specifically a low-pressure expansion valve.

[0022] It should be noted that the first expansion valve 9 is a high-pressure expansion valve, which is the first expansion valve connected after the working fluid flows through two high-pressure stage compressors (the second compressor 5 and the third compressor 6); The second expansion valve 11 is a low-pressure expansion valve, which is the second expansion valve connected after the working fluid flows through two high-pressure stage compressors (second compressor 5 and third compressor 6).

[0023] In practice, the working fluid pressure in the first expansion valve 9 is greater than the working fluid pressure in the second expansion valve 11.

[0024] In this utility model, specifically, the ice rink coil 13 is the core heat exchange component of a traditional ice rink refrigeration system. It is located below the ice surface of the ice rink and is a hollow metal pipe (mostly copper or steel pipe). It is a common component of traditional ice rink refrigeration systems and will not be described in detail here.

[0025] In practice, the ice rink coil 13 is a metal pipe coiled and distributed below the ice surface of the ice rink, with its upper surface in contact with the ice surface.

[0026] In this invention, in a specific implementation, any two interconnected devices are connected by a hollow connecting pipe.

[0027] To better understand the technical solution of this utility model, the functions of each main component and their working principle are explained below.

[0028] The storage tank 1 is used to collect the carbon dioxide working fluid that has absorbed heat in the ice rink after flowing through the ice rink coil 13, and transport it to the first regenerator 2. The first regenerator 2 is used to cool the working fluid flowing out of the outlet of the storage tank 1 by using the working fluid flowing out of the outlet of the flash tank 10. The first compressor 3 is used to compress the working fluid from the first regenerator 2 and transfer it to the precooler 4; The precooler 4 is used to cool the working fluid from the first compressor 3 and transfer it to the second compressor 5 and the third compressor 6; The second compressor 5 and the third compressor 6 are both used to compress the working fluid from the precooler 4 and transfer it to the air cooler 7. The air cooler 7 is used to cool the working fluid from the second compressor 5 and the third compressor 6 and transfer it to the second regenerator 8; The second regenerator 8 is used to pre-cool the working fluid that needs to enter the second compressor 5 and the third compressor 6 by using the working fluid from the air cooler 7. The first expansion valve 9 is used to expand, depressurize and cool the working fluid from the first regenerator 8; The flash tank 10 is used to perform gas-liquid separation of the working fluid from the first expansion valve 9, wherein the working fluid gas enters the first regenerator 8 and the working fluid liquid enters the second regenerator 2. The second expansion valve 11 is used to expand, depressurize and cool the working fluid from the second regenerator 2, and continue to transfer the working fluid to the storage tank 1. The transfer pump 12 is used to transport the working fluid from the storage tank to the ice rink coil 13; The ice rink coil 13 is used to allow the working fluid from the transfer pump 12 to absorb heat in the ice rink, and to transfer the heat-absorbing working fluid to the storage tank 1.

[0029] It should be noted that an ice rink refers to a flat ice surface formed by artificial refrigeration or natural low temperatures, used for sports activities such as skating, ice hockey, and figure skating, or as a low-temperature environment for commercial entertainment and industrial purposes. The ice rink coil 13 is the core heat exchange component of a traditional ice rink refrigeration system. It typically refers to a metal pipe (mostly copper or steel) laid beneath the ice surface, which exchanges heat with the ice surface through a circulating low-temperature refrigerant (such as carbon dioxide, or ethylene glycol solution, or brine) to maintain the frozen state of the ice surface.

[0030] Based on the regenerative transcritical carbon dioxide two-stage compression system provided by this utility model, this utility model also provides a control method for the regenerative transcritical carbon dioxide two-stage compression system, including the following operating modes: First, the low-pressure carbon dioxide working fluid from the storage tank 1 is converted into a superheated state by the first regenerator 2, and then enters the first compressor 3 to be compressed to a medium-low pressure state. Then, the carbon dioxide working fluid is cooled by the precooler 4 and mixed with the high-pressure working fluid flowing out from the second regenerator 8. Next, the mixed carbon dioxide working fluid enters the second compressor 5 and the third compressor 6, where it is compressed to a high temperature and high pressure state (at which point the working fluid has the highest temperature and pressure in the system), and then flows into the air cooler 7 for cooling. Next, the working fluid cooled by the gas cooler 7 enters the second regenerator 8 for further cooling. The working fluid flowing out of the second regenerator 8 enters the first expansion valve 9 for expansion and throttling, becoming a medium-pressure working fluid with gas and liquid phases. It is then fed into the flash tank 10 for gas-liquid separation to obtain a gas phase working fluid and a liquid phase working fluid. The gas phase working fluid is then output to the second regenerator 8, and the liquid phase working fluid is output to the first regenerator 2. In this process, the gaseous working fluid, which serves as the low-temperature medium of the second regenerator 8, is heated and then flows into the second compressor 5 and the third compressor 6 to be compressed into a high-temperature and high-pressure working fluid. Subsequently, the high-temperature and high-pressure working fluid flowing out of the second compressor 5 and the third compressor 6 is cooled by the air cooler 7 and then enters the second regenerator 8 for further cooling. It should be noted that the gaseous working fluid serves as the low-temperature medium of the second regenerator 8, while the liquid working fluid is cooled as the high-temperature medium of the first regenerator 2.

[0031] The liquid working fluid cooled by the first regenerator 2 is introduced into the second expansion valve 11 to reduce pressure and throttle, becoming a low-pressure, low-temperature liquid working fluid. Finally, the liquid working fluid is introduced into the storage tank 1 and pumped into the ice rink coil 13 by the transport pump 12 for evaporation and heat absorption to achieve the refrigeration function, thus completing the entire cycle.

[0032] For a clearer understanding of the technical solution of this utility model, please refer to... Figure 2 The technical solution of this utility model will be described below with reference to specific embodiments.

[0033] The control process of the regenerative transcritical carbon dioxide two-stage compression system provided by this invention can include the following three stages: The first stage is system startup and initialization: During system startup, each component is initialized and tested to ensure normal operation. Then, based on preset parameters such as ambient temperature, evaporation temperature, and air cooler outlet temperature, the speeds of the first compressor 3 (specifically a low-pressure stage compressor), the second compressor 5 and the third compressor 6 (two high-pressure stage compressors), the outlet temperature of the air cooler 7, the opening of the second expansion valve 11 (specifically a low-pressure expansion valve), and the opening of the first expansion valve 9 (specifically a high-pressure expansion valve) are adjusted to bring the system into its initial operating state. The second stage involves monitoring and adjusting operating parameters. During system operation, key system parameters are monitored in real time, such as the back pressure of flash tank 10, the liquid level of storage tank 1, the system's maximum operating pressure, the cooling capacity per unit working fluid, compressor power consumption, and COP. Based on the monitored parameter changes, the speeds of the first compressor 3 (specifically, the low-pressure stage compressor), the second compressor 5 and the third compressor 6 (two high-pressure stage compressors), the outlet temperature of the air cooler 7, the opening of the second expansion valve 11 (specifically, a low-pressure expansion valve), and the opening of the first expansion valve (specifically, a high-pressure expansion valve) are dynamically adjusted in real time to maximize the system COP and optimize system performance. The third stage, maintaining optimal operating state: Through further data analysis and modeling, the optimal combination of operating parameters for the system under different operating conditions can be determined. In actual operation, based on real-time monitoring data, system parameters are adjusted so that the system can quickly adapt to changes in external load and always maintain optimal operating state (that is, so that the system COP returns to its maximum value).

[0034] It should be noted that the system of this utility model adopts a closed-loop control strategy, which monitors the system's performance parameters in real time (the parameters monitored in real time include compressor outlet temperature, air cooler outlet temperature, liquid level in the liquid storage tank, system pressure and load changes), and then adjusts these performance parameters based on energy efficiency indicators (such as COP) to ensure that the system always operates in the optimal state (that is, to keep the system COP at its maximum value).

[0035] Example 1 The regenerative transcritical carbon dioxide two-stage compression system provided by this invention is started under the conditions of an ambient temperature of 15℃ and an evaporation temperature of -18.5℃.

[0036] Initially, the opening of the first expansion valve 9 (specifically a high-pressure expansion valve) is set to 50%, and the outlet temperature of the air cooler 7 is set to 35°C. After the system is running, parameters such as the back pressure of the flash tank 10, the maximum operating pressure of the system, the cooling capacity per unit working fluid, the power consumption of the compressor, and the coefficient of performance (COP) are monitored in real time. Then, based on the monitoring data, the opening degree of the first expansion valve and the outlet temperature of the air cooler 7 are dynamically adjusted.

[0037] When the system COP reaches its maximum value of 2.36 (at which point the system is in its optimal operating state under the aforementioned environmental conditions), the back pressure of the flash tank 10 is recorded as 4.18 MPa, the opening degree of the first expansion valve 9 is set to 47.6%, and the outlet temperature of the air cooler 7 is set to 28°C. In subsequent operation, when the system is detected to deviate from this optimal operating state, the relevant parameters are automatically adjusted to bring it back to the optimal operating state (i.e., the system COP returns to its maximum value of 2.36).

[0038] Example 2 The regenerative transcritical carbon dioxide two-stage compression system provided by this invention is started under the conditions of an ambient temperature of 15℃ and an evaporation temperature of -18℃.

[0039] Initially, the opening of the first expansion valve 9 (specifically a high-pressure expansion valve) is set to 50%, and the outlet temperature of the air cooler 7 is set to 35°C. After the system is running, parameters such as the back pressure of the flash tank 10, the maximum operating pressure of the system, the cooling capacity per unit working fluid, the power consumption of the compressor, and the COP are monitored in real time. Then, based on the monitoring data, the opening degree of the high-pressure expansion valve and the outlet temperature of the air cooler are dynamically adjusted.

[0040] When the system COP reaches its maximum value of 2.61 (at which point the system is in its optimal operating state under the aforementioned environmental conditions), the back pressure of the flash tank 10 is recorded as 4.52 MPa, the opening degree of the first expansion valve 9 is set to 54.3%, and the outlet temperature of the air cooler 7 is set to 30°C. In subsequent operation, if the system is detected to deviate from this optimal operating state, the relevant parameters are automatically adjusted to bring it back to the optimal operating state (i.e., the system COP returns to its maximum value of 2.61).

[0041] In summary, the regenerative transcritical carbon dioxide two-stage compression system of this invention addresses the shortcomings of existing systems in terms of overall cooling and heating energy efficiency by introducing a regenerator and optimizing the control strategy. Furthermore, this system exhibits excellent adaptability and flexibility, automatically adjusting operating parameters according to different operating conditions to achieve efficient and stable cooling performance.

[0042] After testing, the application of this utility model can improve the energy efficiency and adaptability to various operating conditions of existing carbon dioxide ice-making systems. This utility model provides a transcritical carbon dioxide multi-stage ejector ice-making system and control method based on dynamic optimal operating pressure. By adjusting the speed of the low-pressure stage compressor and the high-pressure stage compressor, the outlet temperature of the air cooler, and the opening of the low-pressure expansion valve and the high-pressure expansion valve, the ice-making system is made to operate at the dynamic optimal operating pressure, thereby improving the overall energy utilization efficiency of the ice-making system in a wide working range. The calculation method for the overall energy utilization efficiency is: (cooling capacity + heat recovery capacity) / power consumption.

[0043] In summary, compared with existing technologies, this utility model provides a regenerative transcritical carbon dioxide two-stage compression system and control method. The design is scientific. By introducing a low-pressure regenerator and a high-pressure regenerator, this utility model effectively recovers the energy of the low-temperature carbon dioxide working fluid, saves energy and reduces emissions, and has significant practical significance.

[0044] Furthermore, this invention incorporates a dynamic control strategy to optimize the system's operating status, thereby improving the overall cooling and heating energy efficiency of the carbon dioxide refrigeration system.

[0045] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A regenerative transcritical two-stage carbon dioxide compression system, characterized in that, It includes a liquid storage tank (1), a first regenerator (2), a first compressor (3), a precooler (4), a second compressor (5), a third compressor (6), an air cooler (7), a second regenerator (8), a first expansion valve (9), a flash tank (10), a second expansion valve (11), a transport pump (12), and an ice rink coil (13). The first outlet a of the storage tank (1) is connected to the cold side inlet b of the first regenerator (2); The cold side outlet a of the first regenerator (2) is connected to the working fluid inlet of the first compressor (3); The working fluid outlet of the first compressor (3) is connected to the working fluid inlet of the precooler (4); The working fluid outlet of the precooler (4) is connected to the working fluid inlet of the second compressor (5) and the working fluid inlet of the third compressor (6), respectively; The working fluid outlets of the second compressor (5) and the third compressor (6) are connected to the working fluid inlet of the air cooler (7) after they converge. The working fluid outlet of the air cooler (7) is connected to the hot side inlet c of the second regenerator (8); The hot side outlet d of the second regenerator (8) is connected to the working fluid inlet b of the flash tank (10) through the first expansion valve (9); The cold side outlet a of the second regenerator (8) is connected to the working fluid inlet of the second compressor (5) and the working fluid inlet of the third compressor (6), respectively. The cold side inlet b of the second regenerator (8) is connected to the gaseous working fluid outlet c at the top of the flash tank (10); The liquid working fluid outlet a of the flash tank (10) is connected to the hot side inlet c of the first regenerator (2); The hot side outlet d of the first regenerator (2) is connected to the first inlet b at the top of the storage tank (1) through the second expansion valve (11); The second outlet c at the bottom of the storage tank (1) is connected to the working fluid inlet of the transfer pump (12); The working fluid outlet of the transport pump (12) is connected to the working fluid inlet of the ice rink coil (13); The working fluid outlet of the ice rink coil (13) is connected to the second inlet d at the right end of the liquid storage tank (1).

2. The regenerative transcritical carbon dioxide two-stage compression system as described in claim 1, characterized in that, The working fluid of the system is carbon dioxide.

3. The recuperated transcritical carbon dioxide two-stage compression system of claim 1, wherein, The first compressor (3) is a low-pressure stage compressor; Both the second compressor (5) and the third compressor (6) are high-pressure compressors.

4. The regenerative transcritical carbon dioxide two-stage compression system as described in claim 3, characterized in that, A low-pressure compressor is a compressor with a discharge pressure below 1 MPa; A high-pressure compressor is a compressor with a discharge pressure greater than 10 MPa.

5. The regenerative transcritical carbon dioxide two-stage compression system as described in claim 1, characterized in that, The pressure of the working fluid in the second regenerator (8) is greater than the pressure of the working fluid in the first regenerator (2).

6. The regenerative transcritical two-stage carbon dioxide compression system as described in claim 1, characterized in that, The working fluid pressure in the first expansion valve (9) is greater than the working fluid pressure in the second expansion valve (11).

7. The recuperated transcritical carbon dioxide two-stage compression system of any one of claims 1 to 6, characterized in that, The ice rink coil (13) is a hollow metal pipe located below the ice surface of the ice rink, with its upper surface in contact with the ice surface.

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