Supercritical refrigeration system, refrigeration system control method and control device

Abstract

The application provides a supercritical refrigeration system, a refrigeration system control method and a control device, and relates to the technical field of refrigeration. The supercritical refrigeration system comprises a carbon dioxide circulation pipeline and a load medium pipeline. The carbon dioxide circulation pipeline is sequentially provided with a compressor, a cooler, an expansion valve and an evaporator. The compressor is used for outputting supercritical state carbon dioxide. The cooler is used for introducing heat dissipation medium to cool the flowing carbon dioxide. The load medium pipeline has a parallelly arranged freezing pipe section and a pre-cooling pipe section. The evaporator is connected to the freezing pipe section. The pre-cooling pipe section is provided with a pre-cooler and a control valve. The pre-cooler is connected to the carbon dioxide circulation pipeline and is located between the cooler and the expansion valve. The control valve is used for controlling the flow of the load medium flowing into the pre-cooling pipe section. The supercritical refrigeration system provided by the application can maintain the energy efficiency ratio in an ideal range to continuously operate normally.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration, in particular to a supercritical refrigeration system, a refrigeration system control method and a control device. BACKGROUND

[0002] At present, some supercritical refrigeration systems on the market are composed of a compressor, a cooler, an expansion valve and an evaporator to form a basic refrigerant circulation system. The refrigerant realizes refrigeration of the load medium when flowing through the evaporator. The refrigerant is usually carbon dioxide, which is in a subcritical state at the low-pressure side of the compressor and in a supercritical state at the high-pressure side of the compressor.

[0003] In actual application, such a supercritical refrigeration system often causes the temperature of the carbon dioxide output by the cooler to rise due to the temperature rise of the heat dissipation medium introduced by the cooler, thereby increasing the enthalpy value of the carbon dioxide inlet of the evaporator, weakening the refrigeration effect, and reducing the energy efficiency ratio of the refrigeration system. When the temperature of the carbon dioxide output by the cooler rises to a certain value, the energy efficiency ratio of the refrigeration system will decrease to 1.0 or even below, causing the system to be unable to maintain stability and continue to operate. SUMMARY

[0004] The problem solved by the present application is that the existing supercritical refrigeration system cannot operate normally due to the temperature rise of the heat dissipation medium introduced by the cooler.

[0005] To solve the above problems, the present application provides a supercritical refrigeration system which can maintain the energy efficiency ratio in an ideal range to continue normal operation.

[0006] Embodiments of the present application provide a technical solution:

[0007] A supercritical refrigeration system, comprising a carbon dioxide circulation pipeline and a load medium pipeline, a compressor, a cooler, an expansion valve and an evaporator are sequentially arranged on the carbon dioxide circulation pipeline, the compressor is used to output carbon dioxide in a supercritical state, and the cooler is used to introduce heat dissipation medium to cool the flowing carbon dioxide;

[0008] The load medium pipeline has a refrigeration pipe section and a pre-cooling pipe section arranged in parallel, the evaporator is connected to the refrigeration pipe section, a pre-cooler and a control valve are arranged on the pre-cooling pipe section, the pre-cooler is connected to the carbon dioxide circulation pipeline and is between the cooler and the expansion valve, and the control valve is used to control the flow of the load medium flowing into the pre-cooling pipe section of the load medium pipeline.

[0009] The supercritical refrigeration system provided by the embodiment of the present application has a precooling pipe section connected in parallel with the refrigeration pipe section at both ends of the load medium pipe, and a precooler connected to the carbon dioxide circulation pipe between the cooler and the expansion valve. When the temperature of the heat dissipation medium introduced into the cooler increases to cause the energy efficiency ratio of the refrigeration system to decrease to 1.0, the control valve provided on the precooling pipe section is used to introduce part of the load medium in the load medium pipe into the precooling pipe section before the load medium enters the refrigeration pipe section, so that the carbon dioxide is precooled in the precooler, i.e., the temperature of the carbon dioxide is reduced in advance, thereby reducing the carbon dioxide inlet enthalpy of the evaporator and improving the energy efficiency ratio of the refrigeration system, so that the energy efficiency ratio of the refrigeration system is maintained above 1.0. Therefore, the supercritical refrigeration system provided by the embodiment of the present application can maintain the energy efficiency ratio of the refrigeration system in an ideal range to ensure normal operation.

[0010] In an optional embodiment, the control valve is a three-way valve, the three-way valve has a first input interface, a second input interface and an output interface, the first input interface is connected with the output end of the refrigeration pipe section, the second input interface is connected with the output end of the precooling pipe section, and the output interface is connected with the load medium pipe.

[0011] Through the three-way valve, the on-off state of the precooling pipe section and the flow rate of the load medium flowing through the precooling pipe section can be controlled, so that the precooling effect of the precooler can be controlled.

[0012] In an optional embodiment, the supercritical refrigeration system further comprises a controller and a first temperature detection member, the first temperature detection member is used to detect the temperature of the heat dissipation medium before the heat dissipation medium enters the cooler or the temperature of the carbon dioxide output by the cooler, and the controller is electrically connected with the first temperature detection member and the control valve, and is used to control the control valve to be opened or closed according to the detection result of the first temperature detection member.

[0013] The temperature of the heat dissipation medium before the heat dissipation medium enters the cooler or the temperature of the carbon dioxide output by the cooler is detected by the first temperature detection member, so as to serve as a basis for judging the value of the energy efficiency ratio of the supercritical refrigeration system, and the control valve is controlled according to the detection result of the first temperature detection member, so as to control the energy efficiency ratio and ensure that the energy efficiency ratio is maintained in an ideal range.

[0014] In an optional embodiment, the supercritical refrigeration system further comprises a second temperature detection member, the second temperature detection member is used to detect the temperature of the load medium after the load medium in the load medium pipe flows into the precooling pipe section from the refrigeration pipe section, and the controller is electrically connected with the second temperature detection member and is further used to control the control valve to adjust the flow rate of the load medium flowing into the precooling pipe section from the load medium pipe according to the detection result of the second temperature detection member.

[0015] The second temperature detecting member detects the temperature of the load medium after the refrigeration pipe section and the pre-cooling pipe section are combined, and judges whether the temperature of the combined load medium reaches a target temperature, so as to control the control valve to adjust the flow of the load medium in the load medium pipe into the pre-cooling pipe section, and realize accurate control of the target temperature of the composite medium, so as to meet the refrigeration demand.

[0016] The embodiment of the present application also provides a refrigeration system control method applied to the supercritical refrigeration system, wherein the supercritical refrigeration system comprises a carbon dioxide circulation pipe and a load medium pipe, the carbon dioxide circulation pipe is sequentially provided with a compressor, a cooler, an expansion valve and an evaporator, the compressor is used to output carbon dioxide in a supercritical state, and the cooler is used to introduce a heat dissipation medium to cool the carbon dioxide flowing therethrough; the load medium pipe is provided with a refrigeration pipe section and a pre-cooling pipe section in parallel, the evaporator is connected to the refrigeration pipe section, the pre-cooling pipe section is provided with a pre-cooler and a control valve, the pre-cooler is connected to the carbon dioxide circulation pipe and located between the cooler and the expansion valve, and the control valve is used to control the flow of the load medium in the load medium pipe into the pre-cooling pipe section. The refrigeration system control method comprises the following steps:

[0017] obtaining a first temperature of the heat dissipation medium before entering the cooler or a second temperature of the carbon dioxide output by the cooler;

[0018] in the case that the first temperature is greater than or equal to a first preset temperature or the second temperature is greater than or equal to a second preset temperature, the control valve is controlled to be opened, so that part of the load medium is pre-cooled by the pre-cooler and then flows out of the cooler.

[0019] The refrigeration system control method provided by the embodiment of the present application can maintain the energy efficiency ratio of the supercritical refrigeration system in an ideal range, and ensure that the supercritical refrigeration system continuously and normally operates.

[0020] In an optional embodiment, the compressor is a variable frequency compressor, and after the step of controlling the control valve to be opened, the refrigeration system control method further comprises:

[0021] controlling the control valve to adjust the flow of the load medium flowing through the pre-cooler, and controlling the frequency of the compressor, so that the temperature of the mixed load medium output by the freezing pipe section and the pre-cooling pipe section reaches a target temperature.

[0022] In an optional embodiment, the compressor is a fixed-frequency compressor, and after the step of controlling the control valve to open, the freezing system control method further comprises:

[0023] controlling the control valve to adjust the flow of the load medium flowing through the pre-cooler, so that the temperature of the mixed load medium output by the freezing pipe section and the pre-cooling pipe section reaches a target temperature.

[0024] The embodiment of the present application also provides a freezing system control device applied to the supercritical freezing system.

[0025] The acquisition module is configured to acquire a first temperature of the heat dissipation medium before entering the cooler or a second temperature of the carbon dioxide output by the cooler.

[0026] The control module is configured to control the control valve to open when the first temperature is greater than or equal to a first preset temperature or the second temperature is greater than or equal to a second preset temperature, so that part of the load medium pre-cools the carbon dioxide flowing out of the cooler through the pre-cooler.

[0027] The freezing system control device provided by the embodiment of the present application can maintain the energy efficiency ratio of the supercritical freezing system in an ideal range and ensure the continuous normal operation of the supercritical freezing system.

[0028] In an optional embodiment, the compressor is a variable frequency compressor, and the control module is further configured to control the control valve to adjust the flow rate of the load medium flowing through the precooler, and control the frequency of the compressor, so that the temperature of the mixed load medium output by the refrigeration pipe section and the precooled pipe section reaches a target temperature.

[0029] In an optional embodiment, the compressor is a fixed frequency compressor, and the control module is further configured to control the control valve to adjust the flow rate of the load medium flowing through the precooler, so that the temperature of the mixed load medium output by the refrigeration pipe section and the precooled pipe section reaches a target temperature. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A structural schematic diagram of a supercritical refrigeration system provided for an embodiment of the present application is shown in FIG. 1.

[0031] Figure 2 A flow chart of a refrigeration system control method provided for an embodiment of the present application is shown in FIG. 2.

[0032] Figure 3 A structural block diagram of a refrigeration system control device provided for an embodiment of the present application is shown in FIG. 3.

[0033] REFERENCE SIGNS:

[0034] 100 - supercritical refrigeration system; 110 - carbon dioxide circulation pipeline; 111 - compressor; 112 - cooler; 113 - expansion valve; 114 - evaporator; 120 - load medium pipeline; 121 - refrigeration pipe section; 122 - precooled pipe section; 123 - precooler; 124 - control valve; 200 - refrigeration system control device; 210 - acquisition module; 220 - control module. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] EMBODIMENT

[0037] Please refer to Figure 1 , Figure 1 A structural schematic diagram of a supercritical refrigeration system 100 provided for an embodiment of the present application is shown in FIG. 1.

[0038] The supercritical refrigeration system 100 provided by the embodiment comprises a carbon dioxide circulation pipeline 110 and a load medium pipeline 120, the carbon dioxide circulation pipeline 110 is sequentially provided with a compressor 111, a cooler 112, an expansion valve 113 and an evaporator 114, the compressor 111 is used for outputting supercritical state carbon dioxide, the cooler 112 is used for introducing heat dissipation medium to cool the carbon dioxide flowing therethrough, and the expansion valve 113 plays a role of throttling the carbon dioxide, so that the carbon dioxide flows to the evaporator 114 in a low-temperature and low-pressure state.

[0039] The load medium pipeline 120 has a refrigeration pipe section 121 and a pre-cooling pipe section 122 which are arranged in parallel, the evaporator 114 is connected to the refrigeration pipe section 121, the pre-cooling pipe section 122 is provided with a pre-cooler 123 and a control valve 124, the pre-cooler 123 is connected to the carbon dioxide circulation pipeline 110 and is located between the cooler 112 and the expansion valve 113, and the control valve 124 is used for controlling the flow of the load medium in the load medium pipeline 120 into the pre-cooling pipe section 122.

[0040] It can be understood that the evaporator 114 comprises a carbon dioxide flow channel and a load medium flow channel which are independent of each other, the carbon dioxide flow channel of the evaporator 114 is connected to the carbon dioxide circulation pipeline 110, the load medium flow channel of the evaporator 114 is connected to the refrigeration pipe section 121, the low-temperature and low-pressure state carbon dioxide exchanges heat with the load medium at the evaporator 114, absorbs the heat of the load medium to realize the refrigeration of the load medium, and realizes the basic function of the supercritical refrigeration system 100.

[0041] The pre-cooler 123 also comprises a carbon dioxide flow channel and a load medium flow channel which are independent of each other, the carbon dioxide flow channel of the pre-cooler 123 is connected to the carbon dioxide circulation pipeline 110, the load medium flow channel of the pre-cooler 123 is connected to the pre-cooling pipe section 122, the load medium flowing through the pre-cooler 123 can absorb the heat of the carbon dioxide which is still in a high-temperature state, so as to realize the pre-cooling of the carbon dioxide output by the cooler 112. Whether the load medium flows through the pre-cooling pipe section 122 or not is controlled by the control valve 124.

[0042] In actual application, under the condition that the temperature of the heat dissipation medium introduced into the cooler 112 is normal, the control valve 124 controls the pre-cooling pipe section 122 to be disconnected from the load medium pipeline 120, that is, the load medium in the load medium pipeline 120 flows through the refrigeration pipe section 121, that is, all the load medium is refrigerated by flowing through the evaporator 114. With the increase of the temperature of the heat dissipation medium introduced into the cooler 112, the cooling effect of the heat dissipation medium on the carbon dioxide at the cooler 112 is weakened, so that the temperature of the carbon dioxide output by the cooler 112 is increased, thereby increasing the enthalpy value of the carbon dioxide inlet of the evaporator 114 and weakening the refrigeration effect and the energy efficiency ratio of the refrigeration system.

[0043] To avoid the situation that the COP of the refrigeration system is reduced to 1.0 and the supercritical refrigeration system 100 cannot run normally, before the temperature of the heat-removing medium is increased to a certain value, the pre-cooling pipe section 122 is connected to the load medium pipe 120 by controlling the valve 124, so that part of the load medium in the load medium pipe 120 is diverted into the pre-cooling pipe section 122, and the remaining part still flows into the refrigeration pipe section 121 to release heat normally. The part of the load medium flowing into the pre-cooling pipe section 122 absorbs the heat of the high-temperature carbon dioxide flowing through the pre-cooler 123 when flowing through the pre-cooler 123, so as to pre-cool the carbon dioxide, reduce the carbon dioxide inlet enthalpy of the evaporator 114, improve the COP of the refrigeration system, and maintain the COP of the refrigeration system above 1.0, so as to ensure that the supercritical refrigeration system 100 can run continuously and normally.

[0044] In this embodiment, air is used as the heat-removing medium, and water is used as the load medium. The supercritical refrigeration system 100 is tested, and the test results are as follows:

[0045]

[0046] Under condition 1, the temperature of the heat-removing medium before entering the cooler 112 is 35.0℃, the temperature of the carbon dioxide output by the cooler 112 is 45.7℃, the evaporator 114 inlet enthalpy is 354kJ / kg, the refrigeration effect is 78kJ / kg, and the COP of the refrigeration system is 1.47. The COP of the refrigeration system is greater than 1.0, the supercritical refrigeration system 100 is stable, and the supercritical refrigeration system 100 can run continuously and normally. The carbon dioxide output by the cooler 112 does not need to be pre-cooled, and the control valve 124 controls the pre-cooling pipe section 122 to be disconnected from the load medium pipe 120.

[0047] Under condition 2, the temperature of the heat-removing medium before entering the cooler 112 is increased to 47.4℃. When the high-pressure upper limit is 12.0MPa, the temperature of the carbon dioxide output by the cooler 112 is increased to 56.3℃, the evaporator 114 inlet enthalpy is increased to 367kJ / kg, the refrigeration effect is reduced to 65kJ / kg, and the COP of the refrigeration system is reduced to 1.00. At this time, the supercritical refrigeration system 100 is unstable.

[0048] Condition 3 is that the pre-cooling pipe section 122 is connected to the load medium pipe 120 by controlling the control valve 124 under the condition 2, so that part of the load medium flows through the pre-cooler 123, so as to realize heat exchange between part of the load medium and the carbon dioxide output by the cooler 112 through the pre-cooler 123. It can be seen that the temperature of the carbon dioxide output by the pre-cooler 123 is reduced to 49.5℃, the evaporator 114 inlet enthalpy is reduced to 334kJ / kg, the refrigeration effect is increased to 100kJ / kg, and the COP of the refrigeration system is increased to 1.42. The COP of the refrigeration system is greater than 1.00, the supercritical refrigeration system 100 is stable, and the supercritical refrigeration system 100 can run continuously and normally.

[0049] Under condition 4, the temperature of the heat dissipation medium before entering the cooler 112 is further increased to 57.0°C, the temperature of the carbon dioxide output by the pre-cooler 123 is increased to 55.7°C, the enthalpy value at the inlet of the evaporator 114 is increased to 364 kJ / kg, the refrigeration effect is reduced to 69 kJ / kg, and the energy efficiency ratio of the refrigeration system is reduced to 1.00. At this time, the supercritical refrigeration system 100 becomes unstable.

[0050] It can be seen that the upper limit of the temperature of the heat dissipation medium is increased from 47.4°C to 57.0°C, that is, the operating range in which the supercritical refrigeration system 100 can normally operate is expanded, and the applicability is wider.

[0051] In this embodiment, the control valve 124 is a three-way valve, which has a first input interface, a second input interface, and an output interface. The first input interface is connected with the output end of the refrigeration pipe section 121, the second input interface is connected with the output end of the pre-cooling pipe section 122, and the output interface is connected with the load medium pipeline 120.

[0052] In another embodiment, the three-way valve can be arranged at the input ends of the refrigeration pipe section 121 and the pre-cooling pipe section 122, and other valve devices can be used to replace the three-way valve to control the on-off state of the pre-cooling pipe section 122 and the load medium pipeline 120.

[0053] In fact, the supercritical refrigeration system 100 provided in this embodiment further includes a controller and a first temperature detection member. The first temperature detection member is used to detect the temperature of the heat dissipation medium before entering the cooler 112 or the temperature of the carbon dioxide output by the cooler 112. The controller is electrically connected with the first temperature detection member and the control valve 124, and is used to control the control valve 124 to be opened or closed according to the detection result of the first temperature detection member.

[0054] It can be understood that the energy efficiency ratio of the refrigeration system can be calibrated through the detection result of the first temperature detection member through simulation operation. In other words, when the detection result of the first temperature detection member reaches a certain value, it indicates that the energy efficiency ratio of the refrigeration system at this time is 1.0, and then the controller controls the control valve 124 to be opened to conduct the pre-cooling pipe section 122 and the load medium pipeline 120. For example, in condition 3 of the above test, the temperature of the heat dissipation medium reaches 47.4°C, and the energy efficiency ratio of the refrigeration system is 1.0.

[0055] In fact, in order to ensure that the load medium temperature output by the load medium pipeline 120 reaches the target temperature, the supercritical refrigeration system 100 provided in the embodiment further comprises a second temperature detection member, which is used to detect the load medium temperature after the refrigeration pipeline section 121 and the pre-cooling pipeline section 122 of the load medium pipeline 120 are combined, and the controller is electrically connected with the second temperature detection member and is further used to control the control valve 124 to adjust the load medium flow rate of the load medium pipeline 120 flowing into the pre-cooling pipeline section 122 according to the detection result of the second temperature detection member.

[0056] It should be noted that if the compressor 111 is a variable frequency compressor, the controller can also be electrically connected with the variable frequency compressor, and the controller can control the frequency of the variable frequency compressor in addition to controlling the control valve 124, so that the temperature of the mixed load medium output by the refrigeration pipeline section 121 and the pre-cooling pipeline section 122 reaches the target temperature.

[0057] In summary, the supercritical refrigeration system 100 provided in the embodiment can maintain the energy efficiency ratio in an ideal range to continuously operate normally.

[0058] The embodiment further provides a refrigeration system control method applied to the supercritical refrigeration system 100. Figure 2 , Figure 2 As shown in the flow chart of the refrigeration system control method, the refrigeration system control method can comprise the following steps.

[0059] In step S101, a first temperature before the heat dissipation medium enters the cooler 112 or a second temperature of the carbon dioxide output by the cooler 112 is obtained.

[0060] In step S102, when the first temperature is greater than or equal to a first preset temperature or the second temperature is greater than or equal to a second preset temperature, the control valve 124 is controlled to be opened, so that part of the load medium is pre-cooled by the pre-cooler 123 to flow out of the carbon dioxide output by the cooler 112.

[0061] Specifically, the first temperature detection member in the supercritical refrigeration system 100 can detect the temperature of the heat dissipation medium before entering the cooler 112 or the temperature of the carbon dioxide output by the cooler 112, and the detection result can be used to calibrate the energy efficiency ratio of the refrigeration system.

[0062] When the detection result of the first temperature detection member reaches a certain value, the COP of the refrigeration system at this time is 1.0, and the control valve 124 is opened to connect the pre-cooling pipe section 122 with the load medium pipeline 120, so that part of the load medium is guided to the pre-cooler 123 to absorb the heat of the high-temperature carbon dioxide flowing through the pre-cooler 123, thereby pre-cooling the carbon dioxide, reducing the carbon dioxide inlet enthalpy of the evaporator 114, improving the COP of the refrigeration system, and maintaining the COP above 1.0 to ensure the sustainable normal operation of the supercritical refrigeration system 100.

[0063] If the compressor 111 is a variable frequency compressor, after step S102, the refrigeration system control method can further include the following steps:

[0064] The control valve 124 is controlled to adjust the flow of the load medium flowing through the pre-cooler 123, and the frequency of the compressor 111 is controlled to make the temperature of the mixed load medium output by the refrigeration pipe section 121 and the pre-cooling pipe section 122 reach the target temperature.

[0065] If the compressor 111 is a fixed frequency compressor, after step S102, the refrigeration system control method can further include the following steps:

[0066] The control valve 124 is controlled to adjust the flow of the load medium flowing through the pre-cooler 123 to make the temperature of the mixed load medium output by the refrigeration pipe section 121 and the pre-cooling pipe section 122 reach the target temperature.

[0067] In summary, the refrigeration system control method provided by the embodiment can maintain the COP of the supercritical refrigeration system 100 in an ideal range and ensure the sustainable normal operation of the supercritical refrigeration system 100.

[0068] The embodiment also provides a refrigeration system control device 200 applied to the supercritical refrigeration system 100. Figure 3 , Figure 3 As shown in FIG. 8, the refrigeration system control device 200 can include:

[0069] The acquisition module 210 is configured to acquire the first temperature of the heat dissipation medium before entering the cooler 112 or the second temperature of the carbon dioxide output by the cooler 112.

[0070] The control module 220 is configured to control the control valve 124 to be opened to pre-cool the carbon dioxide flowing out of the cooler 112 by the pre-cooler 123 when the first temperature is greater than or equal to a first preset temperature or the second temperature is greater than or equal to a second preset temperature.

[0071] If the compressor 111 is a variable frequency compressor, the control module 220 is further configured to control the control valve 124 to adjust the flow rate of the load medium flowing through the pre-cooler 123, and control the frequency of the compressor 111, so that the temperature of the mixed load medium output by the refrigeration pipe section 121 and the pre-cooling pipe section 122 reaches the target temperature.

[0072] If the compressor 111 is a fixed frequency compressor, the control module 220 is further configured to control the control valve 124 to adjust the flow rate of the load medium flowing through the pre-cooler 123, so that the temperature of the mixed load medium output by the refrigeration pipe section 121 and the pre-cooling pipe section 122 reaches the target temperature.

[0073] In summary, the control device 200 of the supercritical refrigeration system 100 can maintain the energy efficiency ratio of the supercritical refrigeration system 100 in an ideal range, and ensure the continuous normal operation of the supercritical refrigeration system 100.

[0074] Although the present application has been disclosed as above, it is not limited to the above. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A supercritical refrigeration system, characterized in that, It includes a carbon dioxide circulation pipeline (110) and a load medium pipeline (120). The carbon dioxide circulation pipeline (110) is equipped with a compressor (111), a cooler (112), an expansion valve (113) and an evaporator (114) in sequence. The compressor (111) is used to output supercritical carbon dioxide, and the cooler (112) is used to introduce a heat dissipation medium to cool the flowing carbon dioxide. The load medium pipeline (120) has a refrigeration pipe section (121) and a precooling pipe section (122) arranged in parallel. The evaporator (114) is connected to the refrigeration pipe section (121). The precooling pipe section (122) is equipped with a precooler (123) and a control valve (124). The precooler (123) is connected to the carbon dioxide circulation pipeline (110) and is located between the cooler (112) and the expansion valve (113). The control valve (124) is used to control the load medium flow rate of the load medium pipeline (120) flowing into the precooling pipe section (122).

2. The supercritical refrigeration system according to claim 1, characterized in that, The control valve (124) is a three-way valve. The three-way valve has a first input interface, a second input interface and an output interface. The first input interface is connected to the output end of the refrigeration pipe section (121), the second input interface is connected to the output end of the precooling pipe section (122), and the output interface is connected to the load media pipeline (120).

3. The supercritical refrigeration system according to claim 1, characterized in that, The supercritical refrigeration system (100) further includes a controller and a first temperature sensor. The first temperature sensor is used to detect the temperature of the heat dissipation medium before it enters the cooler (112) or the temperature of the carbon dioxide output by the cooler (112). The controller is electrically connected to the first temperature sensor and the control valve (124) and is used to control the control valve (124) to open or close according to the detection result of the first temperature sensor.

4. The supercritical refrigeration system according to claim 3, characterized in that, The supercritical refrigeration system (100) further includes a second temperature sensor, which is used to detect the temperature of the load medium after the refrigeration section (121) and the precooling section (122) in the load medium pipeline (120) are combined. The controller is electrically connected to the second temperature sensor and is also used to control the control valve (124) to adjust the load medium flow rate of the load medium pipeline (120) into the precooling section (122) according to the detection result of the second temperature sensor.

5. A refrigeration system control method, applied to the supercritical refrigeration system (100) as described in any one of claims 1-4, characterized in that, The refrigeration system control method includes: Obtain a first temperature before the heat dissipation medium enters the cooler (112) or a second temperature of the carbon dioxide output by the cooler (112); When the first temperature is greater than or equal to the first preset temperature or the second temperature is greater than or equal to the second preset temperature, the control valve (124) is opened so that part of the load medium is pre-cooled by the precooler (123) and flows out of the cooler (112) as carbon dioxide.

6. The refrigeration system control method according to claim 5, characterized in that, The compressor (111) is a variable frequency compressor. After the step of controlling the opening of the control valve (124), the refrigeration system control method further includes: The control valve (124) is controlled to regulate the flow rate of the load medium flowing through the precooler (123) and to control the frequency of the compressor (111) so that the temperature of the load medium output from the refrigeration section (121) and the precooling section (122) reaches the target temperature.

7. The refrigeration system control method according to claim 5, characterized in that, The compressor (111) is a fixed-frequency compressor. After the step of controlling the opening of the control valve (124), the refrigeration system control method further includes: The control valve (124) is controlled to adjust the flow rate of the load medium flowing through the precooler (123) so that the temperature of the load medium after mixing with the load medium output from the refrigeration section (121) and the precooling section (122) reaches the target temperature.

8. A refrigeration system control device, applied to the supercritical refrigeration system (100) as described in any one of claims 1-4, characterized in that, The refrigeration system control device (200) includes: The acquisition module (210) is used to acquire a first temperature before the heat dissipation medium enters the cooler (112) or a second temperature of carbon dioxide output by the cooler (112); The control module (220) is used to control the control valve (124) to open when the first temperature is greater than or equal to the first preset temperature or the second temperature is greater than or equal to the second preset temperature, so that part of the load medium is pre-cooled by the precooler (123) and flows out of the cooler (112) as carbon dioxide.

9. The refrigeration system control device according to claim 8, characterized in that, The compressor (111) is a variable frequency compressor. The control module (220) is also used to control the control valve (124) to adjust the flow rate of the load medium flowing through the precooler (123) and to control the frequency of the compressor (111) so that the temperature of the load medium output by the refrigeration pipe section (121) and the precooling pipe section (122) reaches the target temperature.

10. The refrigeration system control device according to claim 8, characterized in that, The compressor (111) is a fixed-frequency compressor. The control module (220) is also used to control the control valve (124) to adjust the flow rate of the load medium flowing through the precooler (123) so that the temperature of the load medium after mixing with the load medium output by the refrigeration pipe section (121) and the precooling pipe section (122) reaches the target temperature.

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