A supercritical carbon dioxide cooling compression system

Abstract

The present application relates to supercritical carbon dioxide power system technical field, provide a kind of supercritical carbon dioxide cooling compression system, including supercritical carbon dioxide cooler, supercritical carbon dioxide compressor, compressor inlet regulating valve, compressor driving motor, multiple densitometers, multiple pressure sensors, data processing unit.Each densitometer and pressure sensor are inserted in supercritical carbon dioxide cooler hot fluid passage, and are provided with the measuring end directly contacted with supercritical carbon dioxide fluid.Data processing unit receives the signal transmitted by multiple densitometers and pressure sensors through cable, accurately predicts the flow and heat transfer performance of supercritical carbon dioxide cooler according to the preset supercritical carbon dioxide property table, and sends speed control signal to compressor driving motor according to the prediction result, and sends opening control signal to compressor inlet regulating valve, significantly improves the system stability and thermal cycle efficiency of supercritical carbon dioxide cooling compression system.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of supercritical carbon dioxide power systems, and particularly relates to a supercritical carbon dioxide cooling and compression system. BACKGROUND

[0002] Supercritical carbon dioxide is very suitable for being used as a heat exchange working medium of a compact cooler due to the characteristics of high density viscosity ratio. However, the working performance of the cooler is unstable due to the disturbance caused by the sudden change of the structure in the cooler because of the fast change of the thermal physical properties of the supercritical carbon dioxide under different thermal physical parameter conditions. It is of great significance to accurately master the thermal physical properties of the working medium in the cooler and to formulate a stable and efficient control strategy of the supercritical carbon dioxide cooling and compression system. SUMMARY

[0003] (I) Technical problem to be solved

[0004] The application provides a supercritical carbon dioxide cooling and compression system, which is used to solve the problem that the working performance of a cooler is unstable due to the disturbance caused by the sudden change of the structure in the cooler because of the fast change of the thermal physical properties of supercritical carbon dioxide under different thermal physical parameter conditions, and achieves the purpose of improving the stability and the thermal cycle efficiency of the supercritical carbon dioxide cooling and compression system.

[0005] (II) Technical scheme

[0006] The supercritical carbon dioxide cooling and compression system comprises a supercritical carbon dioxide cooler, a supercritical carbon dioxide compressor, a compressor inlet regulating valve, a compressor driving motor, a flow meter, a density meter, a pressure sensor and a data processing unit.

[0007] The supercritical carbon dioxide cooler is provided with a cold source channel and a hot fluid channel;

[0008] The rotating shaft of the supercritical carbon dioxide compressor is connected with the motor shaft of the compressor driving motor through a shaft coupling, and the rotating speed of the supercritical carbon dioxide compressor is the same as that of the compressor driving motor;

[0009] The flow meter is installed between the hot fluid channel outlet of the supercritical carbon dioxide cooler and the compressor inlet regulating valve, and is connected with the outlet of the supercritical carbon dioxide cooler and the inlet of the compressor inlet regulating valve through pipelines, and is provided with a cable end for outputting measurement data;

[0010] The number of the density meters and the pressure sensors is greater than or equal to 2, each density meter and each pressure sensor is inserted into the hot fluid channel of the supercritical carbon dioxide cooler, and each density meter and each pressure sensor is provided with a measurement end and a cable end;

[0011] The data processing unit is pre-set with a supercritical carbon dioxide thermophysical property table, a supercritical carbon dioxide flow heat transfer calculation program, a compressor inlet regulating valve characteristic table, and a supercritical carbon dioxide compressor characteristic table. After receiving supercritical carbon dioxide density data transmitted by the densitometer and supercritical carbon dioxide pressure data transmitted by the pressure sensor, it calculates the thermophysical parameters of the hot fluid channel outlet of the supercritical carbon dioxide cooler, sends an opening control signal to the compressor inlet regulating valve, and sends a speed control signal to the compressor drive motor.

[0012] The data processing unit is equipped with a data acquisition terminal that is connected to the cable end of the densitometer and the cable end of the pressure sensor via cables, and a signal output terminal that is connected to the wiring terminals of the compressor inlet regulating valve and the compressor drive motor via cables.

[0013] The medium flowing in the cold source channel of the supercritical carbon dioxide cooler is coolant, and the medium flowing in the hot fluid channel is supercritical carbon dioxide. The outlet of the hot fluid channel is connected to the inlet of the flow meter through a pipe.

[0014] The measuring end of each density meter and pressure sensor is in direct contact with the medium flowing in the hot fluid channel, and the cable end is connected to the data processing unit via a cable.

[0015] The thermophysical parameters of supercritical carbon dioxide at the outlet of the hot fluid channel of the supercritical carbon dioxide cooler vary with the opening degree of the compressor inlet regulating valve.

[0016] The data processing unit's preset supercritical carbon dioxide thermophysical property table describes the relationship between parameters such as density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity of supercritical carbon dioxide fluid. Based on the values ​​of any two of these parameters, the values ​​of all parameters such as density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity can be obtained.

[0017] The data processing unit's preset supercritical carbon dioxide flow heat transfer calculation program can calculate the values ​​of supercritical carbon dioxide fluid velocity, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the outlet of the hot fluid channel based on the thermophysical parameters of the coolant and the values ​​of these parameters.

[0018] The data processing unit's preset supercritical carbon dioxide compressor characteristic table describes the relationship between the supercritical carbon dioxide compressor's speed, efficiency, and thermophysical parameters such as supercritical carbon dioxide flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the hot fluid channel outlet. Based on the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet and the compressor's speed, the supercritical carbon dioxide compressor's efficiency can be obtained. When the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet are constant, the compressor speed corresponding to the optimal efficiency can be calculated based on the supercritical carbon dioxide compressor characteristic table. When the compressor speed is constant, the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet corresponding to the optimal efficiency can be calculated based on the supercritical carbon dioxide compressor characteristic table.

[0019] The data processing unit's preset compressor inlet regulating valve characteristic table describes the relationship between the opening degree of the compressor inlet regulating valve and the thermophysical parameters such as the flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity of supercritical carbon dioxide at the compressor inlet regulating valve. Based on the thermophysical parameters of supercritical carbon dioxide at the compressor inlet regulating valve and the opening degree of the compressor inlet regulating valve, the thermophysical parameters of supercritical carbon dioxide at the compressor inlet regulating valve outlet can be obtained. When the thermophysical parameters of supercritical carbon dioxide at the compressor inlet regulating valve are constant, the opening degree of the compressor inlet regulating valve corresponding to the optimal efficiency of the supercritical carbon dioxide compressor can be calculated based on the compressor inlet regulating valve characteristic table.

[0020] The opening degree of the compressor inlet regulating valve is controlled by the opening degree control signal output from the signal output terminal of the data processing unit, and the speed of the compressor drive motor is controlled by the speed control signal output from the signal output terminal of the data processing unit.

[0021] (III) Technical Effects

[0022] The data processing unit receives signals transmitted via cables from multiple densitometers and pressure sensors. Based on a preset table of supercritical carbon dioxide thermophysical properties, the supercritical carbon dioxide flow heat transfer calculation program accurately predicts the flow and heat transfer performance of the supercritical carbon dioxide cooler. According to the prediction results, it sends speed control signals to the compressor drive motor and opening control signals to the compressor inlet regulating valve, so that the supercritical carbon dioxide compressor operates at the optimal efficiency point, thereby improving the system stability and thermodynamic cycle efficiency of the supercritical carbon dioxide cooling compression system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a supercritical carbon dioxide cooling and compression system provided in an embodiment of the present invention;

[0025] In the diagram: 1-Supercritical carbon dioxide cooler, 2-Supercritical carbon dioxide compressor, 3-Compressor inlet regulating valve, 4-Compressor drive motor, 5-Flow meter, 61-First density meter, 62-Second density meter, 71-First pressure sensor, 72-Second pressure sensor, 8-Data processing unit, 9-Coupling, 11-Cold source channel, 12-Hot fluid channel, 31-Compressor inlet regulating valve terminal, 42-Compressor drive motor terminal, 51-Flow meter cable end, 611-First density meter measuring end, 612-First density meter cable end, 621-Second density meter measuring end, 622-Second density meter cable end, 711-First pressure sensor measuring end, 712-First pressure sensor cable end, 721-Second pressure sensor measuring end, 722-Second pressure sensor cable end, 811-First data acquisition end, 812-Second data acquisition end, 813-Third data acquisition end, 814-Fourth data acquisition end, 815-Fifth data acquisition end.

[0026] Figure 2 This is a schematic diagram of the workflow of a data processing unit provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "thermophysical properties," "pipeline," and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The following is combined Figure 1 The supercritical carbon dioxide cooling and compression system provided in the embodiments of the present invention includes: a supercritical carbon dioxide cooler 1, a supercritical carbon dioxide compressor 2, a compressor inlet regulating valve 3, a compressor drive motor 4, a flow meter 5, a first density meter 61, a second density meter 62, a first pressure sensor 71, a second pressure sensor 72, and a data processing unit 8.

[0030] The supercritical carbon dioxide cooler 1 is provided with a cold source channel 11 and a hot fluid channel 12;

[0031] The inlet of the supercritical carbon dioxide compressor 2 is connected to the outlet of the compressor inlet regulating valve 3 via a pipeline;

[0032] The rotating shaft 21 of the supercritical carbon dioxide compressor 2 is connected to the motor shaft 41 of the compressor drive motor 4 via a coupling 9, and the rotating shaft 21 of the supercritical carbon dioxide compressor 2 and the motor shaft 41 of the compressor drive motor 4 rotate at the same speed.

[0033] The flow meter 5 is installed between the outlet of the hot fluid channel 12 of the supercritical carbon dioxide cooler 1 and the compressor inlet regulating valve 3. The flow meter 5 is connected to the outlet of the hot fluid channel 12 of the supercritical carbon dioxide cooler 1 and the inlet of the compressor inlet regulating valve 3 through a pipe.

[0034] The first densitometer 61, the second densitometer 62, the first pressure sensor 71, and the second pressure sensor 72 are all inserted into the hot fluid channel 12 of the supercritical carbon dioxide cooler 1. The first densitometer 61 is provided with a first densitometer measuring end 611 and a first densitometer cable end 612. The second densitometer 62 is provided with a second densitometer measuring end 621 and a second densitometer cable end 622. The first pressure sensor 71 is provided with a first pressure sensor measuring end 711 and a first pressure sensor cable end 712. The second pressure sensor 72 is provided with a second pressure sensor measuring end 721 and a second pressure sensor cable end 722.

[0035] The first data acquisition terminal 811 of the data processing unit 8 is connected to the cable terminal 612 of the densitometer 61 via a cable; the second data acquisition terminal 812 is connected to the cable terminal 622 of the densitometer 62 via a cable; the third data acquisition terminal 813 is connected to the cable terminal 712 of the pressure sensor 71 via a cable; the fourth data acquisition terminal 814 is connected to the cable terminal 722 of the pressure sensor 72 via a cable; and the fifth data acquisition terminal 815 is connected to the cable terminal 51 of the flow meter via a cable.

[0036] The first signal output terminal 821 of the data processing unit 8 is connected to the compressor inlet regulating valve terminal 31 via a cable, and outputs an opening control signal to the compressor inlet regulating valve 3 to control the opening of the compressor inlet regulating valve 3. The second signal output terminal 822 is connected to the compressor drive motor terminal 42 via a cable, and outputs a speed control signal to the compressor drive motor 4 to control the speed of the compressor drive motor 4.

[0037] The data processing unit 8 is pre-set with a supercritical carbon dioxide thermophysical property table, a supercritical carbon dioxide flow heat transfer calculation program, and a supercritical carbon dioxide compressor characteristic table. After receiving supercritical carbon dioxide density data transmitted by the first density meter 61 and the second density meter 62 and supercritical carbon dioxide pressure data transmitted by the first pressure sensor 71 and the second pressure sensor 72, it calculates the thermophysical parameters of the outlet of the hot fluid channel 12 of the supercritical carbon dioxide cooler 1, sends an opening control signal to the compressor inlet regulating valve 3, and sends a speed control signal to the compressor drive motor.

[0038] The medium flowing in the cold source channel 11 of the supercritical carbon dioxide cooler 1 is coolant, and the medium flowing in the hot fluid channel 12 is supercritical carbon dioxide. The outlet of the hot fluid channel 12 is connected to the inlet of the flow meter 5 through a pipe.

[0039] The first density meter measuring end 611, the second density meter measuring end 621, the first pressure sensor measuring end 711, and the second pressure sensor measuring end 721 are all in direct contact with the supercritical carbon dioxide flowing medium in the hot fluid channel 12.

[0040] The thermophysical parameters of supercritical carbon dioxide at the outlet of hot fluid channel 12 vary with the opening degree of compressor inlet regulating valve 3. Different opening degrees of compressor inlet regulating valve 3 result in different thermophysical parameters of supercritical carbon dioxide at the outlet of hot fluid channel 12. The specific relationship between the opening degree and the thermophysical parameters is determined by the characteristic table of compressor inlet regulating valve 3.

[0041] Combination Figure 2 The workflow of data processing unit 8 is described, including the following steps:

[0042] Step S1: Receive the supercritical carbon dioxide density and pressure measured by densitometers 61 and 62 and pressure sensors 71 and 72.

[0043] Specifically, the data processing unit 8 has a preset table of supercritical carbon dioxide thermophysical properties that describes the relationship between parameters such as density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity of supercritical carbon dioxide fluid. Based on the values ​​of any two of the parameters, the values ​​of all parameters such as density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity can be obtained.

[0044] Step S2: Substitute the received density and pressure measurements into the preset supercritical carbon dioxide thermophysical property table to obtain the supercritical carbon dioxide thermophysical parameters in the hot fluid channel 12.

[0045] Step S3: The preset supercritical carbon dioxide flow heat transfer calculation program reads the supercritical carbon dioxide thermophysical parameters in the hot fluid channel and calculates the supercritical carbon dioxide thermophysical parameters at the outlet of the hot fluid channel 12.

[0046] Specifically, the supercritical carbon dioxide flow heat transfer calculation program preset by the data processing unit 8 calculates the values ​​of parameters such as velocity, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity of the supercritical carbon dioxide fluid at the outlet of the hot fluid channel 12 based on the thermophysical parameters of the coolant.

[0047] Step S4: Substitute the supercritical carbon dioxide thermophysical parameters at the outlet of the hot fluid channel 12 into the preset compressor inlet regulating valve characteristic table to obtain the opening degree of the compressor inlet regulating valve 3 and the supercritical carbon dioxide thermophysical parameters at the outlet of the compressor inlet regulating valve 3.

[0048] Specifically, the supercritical carbon dioxide compressor characteristic table preset by the data processing unit 8 describes the relationship between the supercritical carbon dioxide compressor 2's rotational speed, supercritical carbon dioxide inlet flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity, etc. Based on the supercritical carbon dioxide's thermophysical parameters and the supercritical carbon dioxide compressor 2's rotational speed, the efficiency of the supercritical carbon dioxide compressor 2 can be obtained. When the supercritical carbon dioxide inlet of the supercritical carbon dioxide compressor 2 is constant, the rotational speed of the supercritical carbon dioxide compressor 2 corresponding to the optimal efficiency can be calculated based on the supercritical carbon dioxide compressor 2 characteristic table. When the supercritical carbon dioxide compressor 2's rotational speed is constant, the supercritical carbon dioxide inlet of the supercritical carbon dioxide compressor 2 corresponding to the optimal efficiency can be calculated based on the supercritical carbon dioxide compressor 2 characteristic table.

[0049] Step S5: Send an opening control signal to the compressor inlet regulating valve 3.

[0050] Step S6: Substitute the supercritical carbon dioxide thermophysical parameters at the outlet of the compressor inlet regulating valve 3 into the preset supercritical carbon dioxide compressor characteristic table to obtain the speed corresponding to the optimal efficiency operating point of the supercritical carbon dioxide compressor 2.

[0051] Step S7: Send a speed control signal to the compressor drive motor 4.

[0052] Specifically, the compressor inlet regulating valve characteristic table preset by the data processing unit 8 describes the relationship between the opening degree of the compressor inlet regulating valve 3 and the supercritical carbon dioxide flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity of the supercritical carbon dioxide at the inlet of the compressor inlet regulating valve 3. Based on the thermophysical parameters of the supercritical carbon dioxide at the inlet of the compressor inlet regulating valve 3 and the opening degree of the compressor inlet regulating valve 3, the thermophysical parameters of the supercritical carbon dioxide at the outlet of the compressor inlet regulating valve 3 can be obtained. When the thermophysical parameters of the supercritical carbon dioxide at the inlet of the compressor inlet regulating valve 3 are constant, the opening degree of the compressor inlet regulating valve 3 corresponding to the optimal efficiency of the supercritical carbon dioxide compressor 2 can be calculated based on the compressor inlet regulating valve characteristic table.

[0053] For example, data processing unit 8 receives signals transmitted via cables from two densitometers and two pressure sensors. Based on a preset table of supercritical carbon dioxide thermophysical properties, the supercritical carbon dioxide flow heat transfer calculation program calculates the thermophysical parameters of the supercritical carbon dioxide at the outlet of the hot fluid channel as: temperature 93.68℃, density 455.51 kg / m³. 3 The specific heat is 2.48 kJ / kg·℃, the specific enthalpy is 423.65 kJ / kg, the dynamic viscosity is 3.51E-05 Pa·s, the thermal conductivity is 0.05 W / m·℃, and the flow velocity is 10 m / s. The signal output terminal 82 sends a control signal to the compressor inlet regulating valve 3 to control the opening degree at 50° and a control signal to the compressor drive motor 4 to control the speed at 25000 rpm. At this time, the supercritical carbon dioxide compressor 2 operates stably at the optimal efficiency operating point, and the operating efficiency reaches 85%.

[0054] The supercritical carbon dioxide cooling and compression system provided by this invention receives measurement signals transmitted via cables from multiple densitometers and pressure sensors through a data processing unit. Based on a preset table of supercritical carbon dioxide thermophysical properties, a supercritical carbon dioxide flow heat transfer calculation program accurately predicts the flow and heat transfer performance of the supercritical carbon dioxide cooler. According to the prediction results, the program sends speed control signals to the compressor drive motor and opening control signals to the compressor inlet regulating valve, enabling the supercritical carbon dioxide compressor to operate at its optimal efficiency point, thereby improving the system stability and thermodynamic cycle efficiency of the supercritical carbon dioxide cooling and compression system.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A supercritical carbon dioxide cooling and compression system, comprising: A supercritical carbon dioxide cooler, a supercritical carbon dioxide compressor, a compressor inlet regulating valve, a compressor drive motor, a flow meter, a density meter, a pressure sensor, and a data processing unit are provided, characterized in that the supercritical carbon dioxide cooler is provided with a cold source channel and a hot fluid channel; The inlet of the supercritical carbon dioxide compressor is connected to the outlet of the compressor inlet regulating valve via a pipeline. The rotating shaft of the supercritical carbon dioxide compressor is connected to the motor shaft of the compressor drive motor via a coupling, and the rotational speed of the supercritical carbon dioxide compressor is the same as that of the compressor drive motor. The flow meter is installed between the outlet of the hot fluid channel and the inlet regulating valve of the compressor, and is connected to the outlet of the hot fluid channel and the inlet of the compressor inlet regulating valve respectively through pipes, and is provided with a cable end to output measurement data; The number of the densitometer and the pressure sensor is greater than or equal to 2. Each densitometer and pressure sensor is inserted into the hot fluid channel of the supercritical carbon dioxide cooler. Each densitometer and each pressure sensor is provided with a measuring end and a cable end. The data processing unit has a preset table of supercritical carbon dioxide thermophysical properties, a supercritical carbon dioxide flow heat transfer calculation program, a compressor inlet regulating valve characteristic table, and a supercritical carbon dioxide compressor characteristic table. After receiving the supercritical carbon dioxide density data transmitted by the densitometer and the supercritical carbon dioxide pressure data transmitted by the pressure sensor, it calculates the thermophysical parameters of the hot fluid channel outlet of the supercritical carbon dioxide cooler, sends an opening control signal to the compressor inlet regulating valve, and sends a speed control signal to the compressor drive motor. The data processing unit is provided with a data acquisition terminal connected to the cable end of the densitometer and the cable end of the pressure sensor via cables, and a signal output terminal connected to the wiring terminals of the compressor inlet regulating valve and the compressor drive motor via cables.

2. The supercritical carbon dioxide cooling and compression system according to claim 1, characterized in that, The medium flowing in the cold source channel is coolant, and the medium flowing in the hot fluid channel is supercritical carbon dioxide. The outlet of the hot fluid channel is connected to the inlet of the flow meter via a pipe.

3. The supercritical carbon dioxide cooling and compression system according to claim 1, characterized in that, The measuring end is in direct contact with the medium flowing in the hot fluid channel, and the cable end is connected to the data processing unit via a cable.

4. In the supercritical carbon dioxide cooling and compression system according to claim 1, the supercritical carbon dioxide thermophysical parameters at the outlet of the hot fluid channel and the inlet of the compressor inlet regulating valve change with the opening degree of the compressor inlet regulating valve.

5. A supercritical carbon dioxide cooling and compression system according to claim 1, characterized in that, The preset thermophysical property table of supercritical carbon dioxide describes the relationship between density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity of supercritical carbon dioxide fluid. The values ​​of density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity and thermal conductivity can be obtained by using any two of the parameters.

6. A supercritical carbon dioxide cooling and compression system according to claim 5, characterized in that, The preset supercritical carbon dioxide flow heat transfer calculation program can calculate the values ​​of supercritical carbon dioxide fluid velocity, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the outlet of the hot fluid channel based on the thermophysical parameters of the coolant and the values ​​of the supercritical carbon dioxide fluid flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the outlet of the hot fluid channel.

7. A supercritical carbon dioxide cooling and compression system according to claim 6, characterized in that, A pre-defined supercritical carbon dioxide compressor characteristic table describes the relationship between the supercritical carbon dioxide compressor's rotational speed, efficiency, and the supercritical carbon dioxide flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the outlet of the hot fluid channel. Based on the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet and the compressor's rotational speed, the efficiency of the supercritical carbon dioxide compressor can be obtained. When the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet are constant, the compressor rotational speed corresponding to the optimal efficiency can be calculated using the supercritical carbon dioxide compressor characteristic table. Conversely, when the compressor rotational speed is constant, the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet corresponding to the optimal efficiency can be calculated using the supercritical carbon dioxide compressor characteristic table.

8. A supercritical carbon dioxide cooling and compression system according to claim 7, characterized in that, The preset compressor inlet regulating valve characteristic table describes the relationship between the opening degree of the compressor inlet regulating valve and the supercritical carbon dioxide flow rate, density, pressure, temperature, specific heat, specific enthalpy, dynamic viscosity, and thermal conductivity at the compressor inlet regulating valve. Based on the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet regulating valve and the opening degree of the compressor inlet regulating valve, the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet regulating valve outlet can be obtained. When the thermophysical parameters of the supercritical carbon dioxide at the compressor inlet regulating valve are constant, the opening degree of the compressor inlet regulating valve corresponding to the optimal efficiency of the supercritical carbon dioxide compressor can be calculated based on the compressor inlet regulating valve characteristic table.

9. A supercritical carbon dioxide cooling and compression system according to claim 8, characterized in that, The opening degree of the compressor inlet regulating valve is controlled by the opening degree control signal output from the signal output terminal, and the speed of the compressor drive motor is controlled by the speed control signal output from the signal output terminal.

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