Low-carbon large-temperature-span refrigerating system and control method thereof

Abstract

The invention discloses a low-carbon large-temperature-span refrigerating system and a control method thereof, and relates to the field of refrigerating and cold carrying, the low-carbon large-temperature-span refrigerating system comprises a compressor, a condenser, a first working medium pump, a first connecting mechanism, a second connecting mechanism and a control mechanism, the first connecting mechanism is connected with one outlet of the first working medium pump, and the second connecting mechanism is connected with the other outlet of the first working medium pump. By optimizing the system flow and configuring the low-GWP mixed working medium, the effect of single-stage steam compression ultralow-temperature refrigeration is achieved, on one hand, expansion work generated in the throttling process is recycled through the pressure adjusting attribute of the ejector to improve the system performance, and on the other hand, the flow adjusting attribute of the ejector is used for adjusting the flow of the ejector. Working media of a cold carrying system and a refrigerating system are reasonably and effectively regulated and controlled, so that the concentration of working medium components participating in circulation is precisely regulated and controlled under the aim of refrigerating in different temperature zones.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration and cooling, and in particular to a low-carbon, large-temperature-span refrigeration system and a control method thereof. Background Art

[0002] As global warming and temperatures rise, new refrigeration technology using low-GWP environmentally friendly refrigerants is one of the important development directions in the field of refrigeration and freezing in the future.

[0003] However, limited by the physical properties of the refrigerant and the operating pressure ratio of the compressor, the current single-stage vapor compression refrigeration system cannot achieve refrigeration below -40°C. Possible approaches include replacing the system process with a cascade cycle system, a multi-stage compression system, etc., but this is followed by an increase in system complexity and cost, which is inconvenient. Summary of the invention

[0004] The object of the present invention is to provide a low-carbon, large-temperature-span refrigeration system and a control method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a low-carbon and large temperature span refrigeration system, comprising:

[0006] compressor;

[0007] A condenser and a first working fluid pump, wherein the condenser and the first working fluid pump are sequentially connected to the output end of the compressor;

[0008] A first connecting mechanism, wherein the first connecting mechanism is connected to one of the outlets of the first working fluid pump. The first connecting mechanism comprises:

[0009] a first expansion valve, wherein the first expansion valve is connected to one of the outlets of the first working fluid pump;

[0010] a first ejector, wherein the outlet of the expansion valve is connected to the high-pressure inlet of the first ejector;

[0011] A second connecting mechanism, wherein the second connecting mechanism is connected to another outlet of the first working fluid pump, and the second connecting mechanism comprises:

[0012] a regenerator, wherein a high temperature side inlet of the regenerator is connected to another outlet of the first working fluid pump;

[0013] a second expansion valve and a first gas-liquid separator, wherein the high-temperature outlet of the regenerator is connected to the second expansion valve and the inlet of the first gas-liquid separator in sequence, and the gas phase outlet of the first gas-liquid separator is connected to the outlet of the first ejector, and is connected to the inlet and outlet of the low-temperature side of the regenerator and the inlet of the compressor in sequence;

[0014] a third expansion valve and a second gas-liquid separator, wherein a liquid phase outlet of the first gas-liquid separator is connected to the third expansion valve and the second gas-liquid separator in sequence;

[0015] The evaporator, the liquid phase outlet of the second gas-liquid separator is connected in sequence with the evaporator refrigeration side inlet and outlet, and the first ejector low-pressure inlet;

[0016] a first stop valve, wherein the gas phase outlet of the second gas-liquid separator is connected in sequence to the first stop valve and the low-pressure inlet of the second injector;

[0017] A second ejector, wherein the gas phase outlet of the gas-liquid separator is connected to the stop valve and the low-pressure inlet of the second ejector in sequence, and the outlet of the second ejector is connected to the cold-carrying side inlet of the evaporator;

[0018] A second working fluid pump and a cooling heat exchanger, wherein the second outlet of the cooling side of the evaporator is connected to the second working fluid pump, the cooling heat exchanger and the high-pressure inlet of the second ejector in sequence;

[0019] A second stop valve, wherein the first outlet of the evaporator on the cold side is connected to the second stop valve and the low-pressure inlet of the first ejector in sequence;

[0020] A control mechanism is connected to the compressor, the first connection mechanism and the second connection mechanism.

[0021] Preferably, the control mechanism comprises:

[0022] A control module, wherein an output end of the control module is respectively connected to the compressor, the first expansion valve, the first ejector, the second expansion valve, the expansion valve, the first stop valve, and the second stop valve;

[0023] A first temperature sensor, wherein the first temperature sensor is arranged on the evaporator, and the output end of the control module is connected to the first temperature sensor;

[0024] A component concentration sensor, wherein the component concentration sensor is disposed between the third expansion valve and the second gas-liquid separator, and the output end of the control module is connected to the component concentration sensor;

[0025] A second temperature sensor is provided on the cooling heat exchanger, and an output end of the control module is connected to the second temperature sensor.

[0026] Preferably, the regenerator is provided with a high-temperature side fluid channel and an inlet and an outlet, and a low-temperature side fluid channel and an inlet and an outlet. Heat exchange is performed between the high-temperature side fluid channel and the low-temperature side fluid channel by conduction, convection and radiation, and no mass exchange occurs. The refrigerant component concentrations corresponding to the two fluid channels inside the regenerator are consistent.

[0027] Preferably, the evaporator is provided with a refrigeration side fluid channel and an inlet and an outlet, and a load-cooling side fluid channel and an inlet and an outlet. Heat exchange is performed between the refrigeration side fluid channel and the load-cooling side fluid channel by conduction, convection and radiation, and no mass exchange occurs. The refrigerant component flows in the refrigeration side fluid channel and the inlet and outlet inside the evaporator, and the load-cooling side fluid channel and the inlet and outlet inside the evaporator contains a load-cooling agent component. The load-cooling agent component is a single component carbon dioxide, and the refrigerant component is any combination of methane, ethane, propane and isobutane.

[0028] The present invention also provides a control method for a low-carbon, large-temperature-span refrigeration system, comprising the following specific steps:

[0029] S1: When the cooling temperature is between -20℃ and -40℃, the rated cooling temperature mode is adopted;

[0030] S2: When the refrigeration temperature is between -80℃ and -40℃, the low temperature refrigeration mode is adopted;

[0031] S3: When the cooling temperature is between -20℃ and 0℃, the high temperature cooling mode is adopted.

[0032] Preferably, the rated refrigeration temperature mode in S1 includes:

[0033] S11: The first expansion valve is opened by 50%, and the control module is connected to the first temperature sensor to collect the outlet temperature of the evaporator cooling side;

[0034] S12: When the outlet temperature of the evaporator cooling side is higher than the set rated cooling temperature, gradually reduce the opening of the second expansion valve and the third expansion valve, and increase the compressor speed until the cooling effect of the rated temperature is achieved. Then, maintain the compressor speed unchanged and the opening of the second expansion valve and the third expansion valve unchanged.

[0035] Preferably, the low temperature refrigeration mode in S2 comprises the following steps:

[0036] S21: The first expansion valve is opened 100%, and the control module is connected to the temperature sensor to collect the outlet temperature of the evaporator cooling side;

[0037] S22: The control module is connected to a component concentration sensor to collect the refrigerant components after the third expansion valve, and the control module is connected to a temperature sensor to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger;

[0038] S23: When the refrigerant temperature at the outlet of the refrigerant heat exchanger is above the rated refrigeration temperature, the first stop valve is closed, the second stop valve is opened, the openings of the second expansion valve and the third expansion valve are gradually reduced, and the speed of the compressor is increased;

[0039] S24: When the component concentration sensor collects that the carbon dioxide in the refrigerant component after the third expansion valve exceeds 15%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger reaches the set low-temperature refrigeration temperature, the second stop valve is closed, the compressor speed is maintained unchanged, and the openings of the second expansion valve and the third expansion valve remain unchanged.

[0040] Preferably, the high temperature refrigeration mode in S3 comprises the following steps:

[0041] S31: The first expansion valve is opened by 50%, and the control module is connected to the first temperature sensor to collect the outlet temperature of the evaporator cooling side;

[0042] S32: The control module is connected to the component concentration sensor to collect the refrigerant components after the third expansion valve, and the control module is connected to the second temperature sensor to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger;

[0043] S33: When the refrigerant temperature at the outlet of the refrigerant heat exchanger is below the rated refrigeration temperature, the first stop valve is opened, the second stop valve is closed, the openings of the second expansion valve and the third expansion valve are gradually increased, and the speed of the compressor is reduced;

[0044] S34: When the component concentration sensor collects the carbon dioxide concentration in the refrigerant component after the third expansion valve and the concentration is lower than 1%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger reaches the set high-temperature refrigeration temperature, the first stop valve is closed, the compressor speed is maintained unchanged, and the openings of the second expansion valve and the third expansion valve remain unchanged.

[0045] Technical effects and advantages of the present invention:

[0046] The present invention achieves the effect of single-stage vapor compression ultra-low temperature refrigeration by optimizing the system process and configuring a low GWP mixed working fluid. The pressure regulation property of the ejector is used to recover the expansion work generated in the throttling process to improve system performance. On the other hand, the flow regulation property of the ejector is used to reasonably and effectively regulate the working fluids of the cold-carrying system and the refrigeration system, so that the concentration of the working fluid components participating in the cycle can be accurately regulated under the goal of refrigeration in different temperature zones, which is convenient for use. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic diagram of the process of a low-carbon, large-temperature-span refrigeration system of the present invention.

[0048] In the figure: 101, compressor; 102, condenser; 103, first working fluid pump; 104, first expansion valve; 105, first ejector; 106, regenerator; 107, second expansion valve; 108, first gas-liquid separator; 109, third expansion valve; 110, second gas-liquid separator; 111, evaporator; 112, first stop valve; 113, second ejector; 114, second working fluid pump; 115, cooling heat exchanger; 116, second stop valve; 201, control module; 202, first temperature sensor; 203, component concentration sensor; 204, second temperature sensor. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The present invention provides Figure 1 A low-carbon, large-temperature-span refrigeration system shown includes a compressor 101, a condenser 102, a first working fluid pump 103, a first connecting mechanism, a second connecting mechanism and a control mechanism. The condenser 102 and the first working fluid pump 103 are connected to the output end of the compressor 101 in sequence; the first connecting mechanism is connected to one of the outlets of the first working fluid pump 103; the second connecting mechanism is connected to the other outlet of the first working fluid pump 103; and the control mechanism is connected to the compressor 101, the first connecting mechanism and the second connecting mechanism.

[0051] The first connecting mechanism includes a first expansion valve 104 and a first ejector 105. The first expansion valve 104 is connected to one of the outlets of the first working fluid pump 103; the outlet of the expansion valve is connected to the high-pressure inlet of the first ejector 105. The first expansion valve 104 can throttle and reduce the pressure of the working fluid flowing out of the outlet of the first working fluid pump 103, and provide suitable pressure conditions for the first ejector 105, which helps to improve the energy utilization efficiency of the system. The first ejector 105 can use the pressure difference of the working fluid to achieve an ejection effect, mix the low-temperature and low-pressure working fluid with the high-pressure working fluid, increase the pressure and energy of the working fluid, and promote the circulation of the entire refrigeration system.

[0052] The second connection mechanism includes a regenerator 106, a second expansion valve 107, a first gas-liquid separator 108, a third expansion valve 109, a second gas-liquid separator 110, an evaporator 111, a first stop valve 112, a second ejector 113, a second working fluid pump 114, a cooling heat exchanger 115 and a second stop valve 116. The high-temperature side inlet of the regenerator 106 is connected to the other outlet of the first working fluid pump 103; the high-temperature outlet of the regenerator 106 is connected to the inlets of the second expansion valve 107 and the first gas-liquid separator 108 in sequence, the gas phase outlet of the first gas-liquid separator 108 is connected to the outlet of the first ejector 105, and is connected to the low-temperature side inlet of the regenerator 106 in sequence. and outlet and the inlet of the compressor 101; the liquid phase outlet of the first gas-liquid separator 108 is connected in sequence to the third expansion valve 109 and the second gas-liquid separator 110; the liquid phase outlet of the second gas-liquid separator 110 is connected in sequence to the inlet and outlet of the refrigeration side of the evaporator 111 and the low-pressure inlet of the first ejector 105; the gas phase outlet of the second gas-liquid separator 110 is connected in sequence to the first stop valve 112 and the low-pressure inlet of the second ejector 113; the gas phase outlet of the gas-liquid separator is connected in sequence to the stop valve and the low-pressure inlet of the second ejector 113, and the outlet of the second ejector 113 is connected to the inlet of the cooling side of the evaporator 111; the second outlet of the cooling side of the evaporator 111 is connected in sequence to the second The working fluid pump 114, the cooling heat exchanger 115 and the high-pressure inlet of the second ejector 113 are connected; the first outlet of the cooling side of the evaporator 111 is connected to the second stop valve 116 and the low-pressure inlet of the first ejector 105 in sequence; the regenerator 106 can realize heat recovery and transfer, and transfer the heat of the working fluid flowing out of the high-temperature side to the working fluid on the low-temperature side, thereby improving energy utilization efficiency and reducing energy loss; the second expansion valve 107 can further throttle and reduce the pressure of the working fluid flowing out of the high-temperature outlet of the regenerator 106, in preparation for subsequent gas-liquid separation and other processes; the first gas-liquid separator 108 can separate the gas-liquid mixed working fluid; the gas phase part can be mixed with the working fluid at the outlet of the first ejector 105, and the liquid phase part can be mixed with the working fluid at the outlet of the first ejector 105. The liquid phase can enter the second gas-liquid separator 110 after passing through the third expansion valve 109 to achieve preliminary separation and graded utilization of the working fluid. The second gas-liquid separator 110 also plays the role of gas-liquid separation. The liquid phase part enters the evaporator 111 for refrigeration, and the gas phase part participates in subsequent injection and other processes to ensure the purity and rational utilization of the working fluid in the system. The evaporator 111 realizes the refrigeration function through the circulation of the cold side. The first stop valve 112 and the second stop valve 116 can control the on and off of the working fluid, which is convenient for system adjustment and maintenance. The second ejector 113 uses working fluids of different pressures for injection, and cooperates with the cold heat exchanger 115 to further improve the refrigeration effect and energy utilization efficiency of the system.

[0053] The control mechanism includes a control module 201, a first temperature sensor 202, a component concentration sensor 203 and a second temperature sensor 204. The output end of the control module 201 is respectively connected to the compressor 101, the first expansion valve 104, the first ejector 105, the second expansion valve 107, the first gas-liquid separator 108, the first stop valve 112 and the second stop valve 116; the temperature sensor is arranged on the evaporator 111, and the output end of the control module 201 is connected to the first temperature sensor 202; the component concentration sensor 203 is arranged on the third expansion valve 109 Between the second gas-liquid separator 110, the output end of the control module 201 is connected to the component concentration sensor 203; the second temperature sensor 204 is arranged on the cooling heat exchanger 115, and the output end of the control module 201 is connected to the second temperature sensor 204. The setting of the control mechanism enables the system to be precisely controlled according to different working conditions and requirements. Through the connection between the control module 201 and various components, the operating parameters of the system, such as temperature, component concentration, etc., can be monitored and adjusted in real time to ensure that the system operates in the best state and improve the stability and reliability of the system.

[0054] The regenerator 106 is provided with a high-temperature side fluid channel and an inlet and an outlet, and a low-temperature side fluid channel and an inlet and an outlet. Heat exchange is performed between the high-temperature side fluid channel and the low-temperature side fluid channel by conduction, convection and radiation, and no mass exchange occurs. The refrigerant component concentrations corresponding to the two fluid channels inside the regenerator 106 are consistent.

[0055] The evaporator 111 is provided with a refrigeration side fluid channel and an inlet and an outlet, and a load-cooling side fluid channel and an inlet and an outlet. Heat exchange is carried out between the refrigeration side fluid channel and the load-cooling side fluid channel by conduction, convection and radiation, and no mass exchange occurs. The refrigerant component flows in the refrigeration side fluid channel and the inlet and outlet inside the evaporator 111, and the load-cooling side fluid channel and the inlet and outlet inside the evaporator 111 flows in the load-cooling side fluid channel. The load-cooling component is a single component carbon dioxide, and the refrigerant component is any combination of methane, ethane, propane and isobutane. Any combination of methane, ethane, propane and isobutane can be selected according to the target refrigeration temperature.

[0056] The present invention also provides a control method for a low-carbon and large temperature span refrigeration system, comprising the following method:

[0057] S1: When the refrigeration temperature is between -20℃ and -40℃, the rated refrigeration temperature mode is adopted and the target rated refrigeration temperature is determined according to the established refrigerant composition;

[0058] S2: When the refrigeration temperature is between -80℃ and -40℃, the low-temperature refrigeration mode is adopted, and the refrigerant carbon dioxide in the refrigeration process is introduced into the refrigeration process. By increasing the low-temperature refrigerant components participating in the circulation of the refrigeration process, a low-temperature refrigeration effect lower than the rated refrigeration temperature is achieved;

[0059] S3: When the refrigeration temperature is between -20℃ and 0℃, a high-temperature refrigeration mode is adopted. The gaseous low-temperature refrigerant rich in carbon dioxide in the refrigeration process is extracted to the cold-carrying process through the second ejector 113. By reducing the low-temperature refrigerant components participating in the circulation of the refrigeration process, a refrigeration effect higher than the rated refrigeration temperature is achieved.

[0060] Rated cooling temperature modes in S1 include:

[0061] S11: the first expansion valve 104 is opened by 50%, and the control module 201 is connected to the first temperature sensor 202 to collect the outlet temperature of the cooling side of the evaporator 111;

[0062] S12: If the outlet temperature value of the evaporator 111 on the cooling side is higher than the set rated cooling temperature, gradually reduce the opening of the second expansion valve 107 and the third expansion valve 109, and increase the speed of the compressor 101 until the cooling effect of the rated temperature is achieved, and then maintain the speed of the compressor 101 unchanged, and the opening of the second expansion valve 107 and the third expansion valve 109 unchanged;

[0063] The S2 low temperature refrigeration mode includes the following steps:

[0064] S21: the first expansion valve 104 is opened 100%, and the control module 201 is connected to the first temperature sensor 202 to collect the outlet temperature of the evaporator 111 on the cooling side;

[0065] S22: the control module 201 is connected to the component concentration sensor 203 to collect the refrigerant components after the third expansion valve 109, and the control module 201 is connected to the second temperature sensor 204 to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger 115;

[0066] S23: If the outlet temperature of the refrigerant of the refrigerant heat exchanger 115 is higher than or equal to the rated refrigeration temperature, close the first stop valve 112, open the second stop valve 116, gradually reduce the opening of the second expansion valve 107 and the third expansion valve 109, and increase the speed of the compressor 101;

[0067] S24: If the carbon dioxide in the refrigerant component after the third expansion valve 109 collected by the component concentration sensor 203 exceeds 15%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger 115 reaches the set low-temperature refrigeration temperature, close the second stop valve 116, maintain the speed of the compressor 101 unchanged, and keep the openings of the second expansion valve 107 and the third expansion valve 109 unchanged.

[0068] The S3 medium and high temperature cooling mode includes the following steps:

[0069] S31: the first expansion valve 104 is opened by 50%, and the control module 201 is connected to the first temperature sensor 202 to collect the outlet temperature of the cooling side of the evaporator 111;

[0070] S32: the control module 201 is connected to the component concentration sensor 203 to collect the refrigerant components after the third expansion valve 109, and the control module 201 is connected to the second temperature sensor 204 to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger 115;

[0071] S33: If the outlet temperature of the refrigerant of the refrigerant heat exchanger 115 is lower than or equal to the rated refrigeration temperature, the first stop valve 112 is opened, the second stop valve 116 is closed, the openings of the second expansion valve 107 and the third expansion valve 109 are gradually increased, and the speed of the compressor 101 is reduced;

[0072] S34: If the carbon dioxide concentration in the refrigerant component after the third expansion valve 109 collected by the component concentration sensor 203 is lower than 1%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger 115 reaches the set high-temperature refrigeration temperature, close the first stop valve 112, maintain the speed of the compressor 101 unchanged, and keep the openings of the second expansion valve 107 and the third expansion valve 109 unchanged.

[0073] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-carbon, large temperature span refrigeration system, characterized in that: include: Compressor (101); A condenser (102) and a first working fluid pump (103), wherein the condenser (102) and the first working fluid pump (103) are connected in sequence to the output end of the compressor (101); A first connecting mechanism, the first connecting mechanism being connected to one of the outlets of the first working fluid pump (103), the first connecting mechanism comprising: A first expansion valve (104), the first expansion valve (104) being connected to one of the outlets of the first working fluid pump (103); A first ejector (105), wherein the outlet of the expansion valve is connected to the high-pressure inlet of the first ejector (105); A second connecting mechanism, the second connecting mechanism is connected to another outlet of the first working fluid pump (103), and the second connecting mechanism comprises: a regenerator (106), wherein a high temperature side inlet of the regenerator (106) is connected to another outlet of the first working fluid pump (103); a second expansion valve (107) and a first gas-liquid separator (108), the high-temperature outlet of the regenerator (106) being connected in sequence to the second expansion valve (107) and the inlet of the first gas-liquid separator (108), the gas phase outlet of the first gas-liquid separator (108) being connected to the outlet of the first ejector (105), and being connected in sequence to the inlet and outlet of the low-temperature side of the regenerator (106) and the inlet of the compressor (101); a third expansion valve (109) and a second gas-liquid separator (110), wherein a liquid phase outlet of the first gas-liquid separator (108) is connected to the third expansion valve (109) and the second gas-liquid separator (110) in sequence; An evaporator (111), wherein the liquid phase outlet of the second gas-liquid separator (110) is connected in sequence to the refrigeration side inlet and outlet of the evaporator (111) and the low-pressure inlet of the first ejector (105); a first stop valve (112), wherein the gas phase outlet of the second gas-liquid separator (110) is connected in sequence to the first stop valve (112) and the low-pressure inlet of the second ejector (113); A second ejector (113), wherein the gas phase outlet of the gas-liquid separator is connected to the stop valve and the low-pressure inlet of the second ejector (113) in sequence, and the outlet of the second ejector (113) is connected to the cold-carrying side inlet of the evaporator (111); A second working fluid pump (114) and a cooling heat exchanger (115), wherein the second outlet of the cooling side of the evaporator (111) is connected in sequence to the second working fluid pump (114), the cooling heat exchanger (115) and the high-pressure inlet of the second ejector (113); A second stop valve (116), wherein the first outlet of the cold-carrying side of the evaporator (111) is connected in sequence to the second stop valve (116) and the low-pressure inlet of the first ejector (105); A control mechanism is connected to the compressor (101), the first connecting mechanism and the second connecting mechanism.

2. A low-carbon, wide-temperature-span refrigeration system according to claim 1, characterized in that: The control mechanism comprises: A control module (201), wherein an output end of the control module (201) is respectively connected to the compressor (101), the first expansion valve (104), the first ejector (105), the second expansion valve (107), the first gas-liquid separator (108), the first stop valve (112), and the second stop valve (116); A first temperature sensor (202), the first temperature sensor (202) being arranged on the evaporator (111), and the output end of the control module (201) being connected to the first temperature sensor (202); A component concentration sensor (203), the component concentration sensor (203) being arranged between the third expansion valve (109) and the second gas-liquid separator (110), and the output end of the control module (201) being connected to the component concentration sensor (203); A second temperature sensor (204), the second temperature sensor (204) is arranged on the cooling heat exchanger (115), and the output end of the control module (201) is connected to the second temperature sensor (204).

3. A low-carbon, wide-temperature-span refrigeration system according to claim 1, characterized in that: The regenerator (106) is provided with a high-temperature side fluid channel and an inlet and an outlet, and a low-temperature side fluid channel and an inlet and an outlet. Heat exchange is performed between the high-temperature side fluid channel and the low-temperature side fluid channel by conduction, convection and radiation, and no mass exchange occurs. The refrigerant component concentrations corresponding to the two fluid channels inside the regenerator (106) are consistent.

4. A low-carbon, wide-temperature-span refrigeration system according to claim 1, characterized in that: The evaporator (111) is provided with a refrigeration side fluid channel and an inlet and an outlet, and a load side fluid channel and an inlet and an outlet. Heat exchange is performed between the refrigeration side fluid channel and the load side fluid channel by conduction, convection and radiation, and no mass exchange occurs. A refrigerant component flows in the refrigeration side fluid channel and the inlet and outlet of the evaporator (111), and a load side fluid channel and the inlet and outlet of the evaporator (111) is a load side fluid component. The load side fluid component is a single component carbon dioxide. The refrigerant component is any combination of methane, ethane, propane and isobutane.

5. A control method for a low-carbon, large-temperature-span refrigeration system, characterized in that: The following methods are included: S1: When the cooling temperature is between -20℃ and -40℃, the rated cooling temperature mode is adopted; S2: When the refrigeration temperature is between -80℃ and -40℃, the low temperature refrigeration mode is adopted; S3: When the cooling temperature is between -20℃ and 0℃, the high temperature cooling mode is adopted.

6. The control method of a low-carbon and large temperature span refrigeration system according to claim 5, characterized in that: The rated cooling temperature modes in S1 include: S11: the first expansion valve (104) is opened by 50%, and the control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (111); S12: When the outlet temperature value of the refrigeration side of the evaporator (111) is higher than the set rated refrigeration temperature, the openings of the second expansion valve (107) and the third expansion valve (109) are gradually reduced, and the speed of the compressor (101) is increased until the refrigeration load effect of the rated temperature is achieved, and the speed of the compressor (101) is maintained unchanged, and the openings of the second expansion valve (107) and the third expansion valve (109) are maintained unchanged.

7. The control method of a low-carbon and large temperature span refrigeration system according to claim 5, characterized in that: The low temperature refrigeration mode in S2 comprises the following steps: S21: the first expansion valve (104) is opened 100%, and the control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (111); S22: the control module (201) is connected to the component concentration sensor (203) to collect the refrigerant components after the third expansion valve (109), and the control module (201) is connected to the second temperature sensor (204) to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger (115); S23: When the refrigerant temperature at the outlet of the refrigerant heat exchanger (115) is above the rated refrigeration temperature, the first stop valve (112) is closed, the second stop valve (116) is opened, the openings of the second expansion valve (107) and the third expansion valve (109) are gradually reduced, and the speed of the compressor (101) is increased; S24: When the component concentration sensor (203) collects the carbon dioxide in the refrigerant component after the third expansion valve (109) and it exceeds 15%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger (115) reaches the set low-temperature refrigeration temperature, the second stop valve (116) is closed, the speed of the compressor (101) is maintained unchanged, and the openings of the second expansion valve (107) and the third expansion valve (109) remain unchanged.

8. The control method of a low-carbon and large temperature span refrigeration system according to claim 5, characterized in that: The high temperature refrigeration mode in S3 includes the following steps: S31: the first expansion valve (104) is opened by 50%, and the control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (111); S32: the control module (201) is connected to the component concentration sensor (203) to collect the refrigerant components after the third expansion valve (109), and the control module (201) is connected to the second temperature sensor (204) to collect the refrigerant temperature at the outlet of the refrigerant heat exchanger (115); S33: When the refrigerant temperature at the outlet of the refrigerant heat exchanger (115) is below the rated refrigeration temperature, the first stop valve (112) is opened, the second stop valve (116) is closed, the openings of the second expansion valve (107) and the third expansion valve (109) are gradually increased, and the speed of the compressor (101) is reduced; S34: When the component concentration sensor (203) collects the carbon dioxide concentration in the refrigerant component after the third expansion valve (109) and the concentration is lower than 1%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger (115) reaches the set high-temperature refrigeration temperature, the first stop valve (112) is closed, the speed of the compressor (101) is maintained unchanged, and the openings of the second expansion valve (107) and the third expansion valve (109) remain unchanged.

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