Advanced environment-friendly refrigerating system and control method thereof

Abstract

The advanced environment-friendly refrigerating system comprises a compressor, a condenser and a first working medium pump which are sequentially connected to the outlet end of the compressor, a first expansion valve and a first ejector which are sequentially connected to the outlet end of the first working medium pump, and a heat regenerator connected to the outlet end of the first working medium pump. The second ejector is connected with an outlet of the liquid storage device, the liquid storage device is connected with the heat regenerator through a pipeline, and the evaporator and the cold-carrying heat exchanger are connected with the liquid storage device and the heat regenerator through pipelines. According to the advanced environment-friendly refrigeration system and the control method thereof, the creative effect of single-stage steam compression ultralow-temperature refrigeration is achieved by optimizing the system process and configuring the low-GWP mixed working medium; on one hand, expansion work generated in the throttling process is recycled to improve the system performance through the pressure adjusting attributes of the first ejector and the second ejector, and on the other hand, working media of a cold carrying system and a refrigerating system are reasonably and effectively adjusted and controlled through the flow adjusting attributes of the ejectors.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration systems, and in particular to an advanced environmentally friendly refrigeration system and a control method thereof. Background Art

[0002] As the global climate warms and temperatures rise, new refrigeration technology using low GWP environmentally friendly refrigerants is one of the important development directions in the future refrigeration and freezing field. GWP is an indicator to measure the contribution of greenhouse gases to global warming. GWP environmentally friendly refrigerants refer to those with lower GWP values. They have less impact on global warming and are therefore considered to be a more environmentally friendly option.

[0003] However, restricted 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, resulting in certain defects. Summary of the invention

[0004] The object of the present invention is to provide an advanced environmentally friendly refrigeration system and a control method thereof to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an advanced environmentally friendly refrigeration system, comprising a compressor, a condenser, a first working fluid pump, a first expansion valve, a first ejector, a regenerator, a second expansion valve, a gas-liquid separator, a third expansion valve, an evaporator, a liquid reservoir, a second ejector, a liquid reservoir heat exchanger, a first stop valve, a second working fluid pump, a cold heat exchanger, a second stop valve, a third stop valve and a control component, wherein the compressor outlet is connected to the condenser and the working fluid pump in sequence, the working fluid pump outlet is divided into two paths and respectively connected to the expansion valve and the high-temperature side inlet of the regenerator, the expansion valve outlet is connected to the ejector high-pressure inlet, the high-temperature outlet of the regenerator is connected to the expansion valve and the gas-liquid separator inlet in sequence, the gas phase outlet of the gas-liquid separator is connected to the ejector outlet, and then connected to the low-temperature side inlet and outlet of the regenerator, the compressor outlet and the high-temperature side inlet of the regenerator in sequence. The inlet of the machine is connected, the liquid phase outlet of the gas-liquid separator is connected to the expansion valve, the evaporator refrigeration side inlet and outlet in sequence, the gas phase outlet of the gas-liquid separator is connected to the stop valve inlet, the stop valve outlet is connected to the liquid reservoir inlet, the liquid reservoir outlet is divided into two paths, one is connected to the high-pressure inlet of the ejector, the ejector outlet is connected to the expansion valve outlet and then to the refrigerant side inlet of the evaporator, the other outlet of the liquid reservoir is connected to the outlet of the cold-carrying heat exchanger through the stop valve, the cold-carrying side outlet of the evaporator is connected to the working fluid pump and the cold-carrying heat exchanger in sequence, the cold-carrying heat exchanger outlet is connected to the stop valve and then to the inlet and outlet of the liquid storage heat exchanger, the liquid storage heat exchanger outlet is divided into two paths, one is connected to the low-pressure inlet of the ejector through the stop valve, and the other is connected to the cold-carrying side inlet of the evaporator, and the liquid storage heat exchanger is placed in the liquid reservoir.

[0006] Preferably, the interior of the liquid storage heat exchanger is used for flowing coolant, the interior of the liquid reservoir is used for flowing refrigerant, the inner cavity of the liquid storage heat exchanger and the interior of the liquid reservoir are not connected to each other, and the liquid storage heat exchanger is used for heat exchange with the liquid reservoir.

[0007] Preferably, the control component comprises:

[0008] A first temperature sensor, wherein the first temperature sensor is connected to the evaporator;

[0009] A second temperature sensor, wherein the second temperature sensor is connected to the cooling heat exchanger;

[0010] A component concentration sensor, wherein the component concentration sensor is connected to the pipeline at the inlet end of the evaporator;

[0011] A control module, wherein the input end of the control module is electrically connected to the first temperature sensor, the second temperature sensor and the component concentration sensor, and the output end of the control module is electrically connected to the compressor, the first expansion valve, the first ejector, the first stop valve, the second stop valve, the third stop valve, the second expansion valve and the third expansion valve.

[0012] The present invention also provides a control method for an advanced environmentally friendly refrigeration system, comprising the following specific use steps: comprising a rated refrigeration temperature mode, when the rated refrigeration temperature mode is working, firstly close the first stop valve, close the second stop valve, close the third stop valve, and open the first expansion valve;

[0013] The control module is connected to the first temperature sensor to collect the outlet temperature of the evaporator on the cooling side. When the outlet temperature of the evaporator on the cooling side is higher than the set rated refrigeration temperature, the opening of the second expansion valve and the third expansion valve is gradually reduced, and the speed of the compressor is increased until the refrigeration load effect of the rated temperature is achieved. The speed of the compressor is maintained unchanged, and the opening of the second expansion valve and the third expansion valve remain unchanged.

[0014] Preferably, it includes a low-temperature refrigeration mode. When the low-temperature refrigeration mode is working, the first expansion valve is opened %, the control module is connected to the first temperature sensor to collect the outlet temperature of the evaporator refrigeration side, 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 cold heat exchanger. When the refrigerant temperature at the outlet of the cold heat exchanger is higher than or equal to the rated refrigeration temperature;

[0015] Open the third stop valve, open the first stop valve, close the second stop valve, gradually reduce the opening of the second expansion valve and the third expansion valve, increase the compressor speed, when the component concentration sensor collects that the carbon dioxide in the refrigerant component after the third expansion valve exceeds %, and the refrigerant temperature at the outlet of the refrigerant heat exchanger reaches the set low-temperature refrigeration temperature, close the third stop valve, close the first stop valve, maintain the compressor speed unchanged, and keep the opening of the second expansion valve and the third expansion valve unchanged.

[0016] Preferably, it includes a high-temperature refrigeration mode, the first expansion valve is opened %, the control module is connected to the first temperature sensor to collect the outlet temperature of the evaporator refrigeration side, the control module is connected to the component concentration sensor to collect the refrigerant component 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 cooling heat exchanger;

[0017] When the refrigerant temperature at the outlet of the refrigerant heat exchanger is lower than or equal to the rated refrigeration temperature, open the second stop valve, close the third stop valve, close the first stop valve, gradually increase the opening of the second expansion valve and the third expansion valve, and reduce the compressor speed;

[0018] When the component concentration sensor collects the carbon dioxide concentration in the refrigerant component after the third expansion valve is lower than %, and the refrigerant temperature at the outlet of the cold heat exchanger reaches the set high-temperature refrigeration temperature, the second stop valve is closed, the compressor speed is maintained unchanged, and the openings of the second and third expansion valves remain unchanged.

[0019] Technical effects and advantages of the present invention:

[0020] The present invention utilizes an advanced environmentally friendly refrigeration system and a control method thereof, optimizes the system process and configures a low-GWP mixed working fluid, thereby achieving the creative effect of single-stage vapor compression ultra-low temperature refrigeration. The pressure regulation property of the ejector is used to recover the expansion work generated in the throttling process to improve the system performance on the one hand, and the flow regulation property of the first ejector and the second ejector is used to reasonably and effectively regulate the cooling system and the working fluid of the refrigeration system. At the same time, a liquid storage heat exchanger is placed in the liquid storage tank, and the cold capacity of the coolant is used to condense the high-pressure low-boiling point rich components, so that under the goal of refrigeration in different temperature zones, the concentration of the working fluid components participating in the cycle can be accurately regulated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the process structure of the present invention.

[0022] 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, gas-liquid separator; 109, third expansion valve; 110, evaporator; 111, liquid storage; 112, second ejector; 113, liquid storage heat exchanger; 114, first stop valve; 115, second working fluid pump; 116, cooling heat exchanger; 117, second stop valve; 118, third stop valve; 201, control module; 202, first temperature sensor; 203, component concentration sensor; 204, second temperature sensor. DETAILED DESCRIPTION

[0023] 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.

[0024] The present invention provides Figure 1An advanced environmentally friendly refrigeration system shown includes a compressor 101, a condenser 102, a first working fluid pump 103, a first expansion valve 104, a first ejector 105, a regenerator 106, a second expansion valve 107, a gas-liquid separator 108, a third expansion valve 109, an evaporator 110, a liquid storage 111, a second ejector 112, a liquid storage heat exchanger 113, a first stop valve 114, a second working fluid pump 115, a cooling heat exchanger 116, a second stop valve 117, a third stop valve 118 and a control component. The compressor 101 is used to compress a refrigerant. The cooling fluid component is a single component of carbon dioxide. The refrigerant component is a mixed working fluid. According to the target refrigeration temperature, any combination of methane, ethane, propane and isobutane is selected. The compressor The outlet 101 is connected to the condenser 102 and the working fluid pump 103 in sequence. The outlet of the working fluid pump 103 is divided into two paths and is respectively connected to the expansion valve 104 and the high-temperature side inlet of the regenerator 106. The regenerator 106 includes two different fluid channels, namely the high-temperature side fluid channel and its inlet and outlet, and the low-temperature side fluid channel and its inlet and outlet. The high-temperature side fluid channel and the low-temperature side fluid channel exchange heat through 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. The outlet of the expansion valve 104 is connected to the high-pressure inlet of the ejector 105. The high-temperature outlet of the regenerator 106 is connected to the expansion valve 107 and the inlet of the gas-liquid separator 108 in sequence. The gas phase outlet of the gas-liquid separator 108 is connected to the ejector 105. After being connected to the outlet of the regenerator 105, it is connected to the low-temperature side inlet and outlet of the regenerator 106 and the inlet of the compressor 101 in sequence. The liquid phase outlet of the gas-liquid separator 108 is connected to the expansion valve 109 and the refrigeration side inlet and outlet of the evaporator 110 in sequence. The gas phase outlet of the gas-liquid separator 108 is connected to the inlet of the stop valve 118, and the outlet of the stop valve 118 is connected to the inlet of the liquid storage 111. The outlet of the liquid storage 111 is divided into two paths, one of which is connected to the high-pressure inlet of the ejector 112. The outlet of the ejector 112 is connected to the outlet of the expansion valve 109 and then to the refrigerant side inlet of the evaporator 110. The other outlet of the liquid storage 111 is connected to the outlet of the cold-carrying heat exchanger 116 through the stop valve 117. The outlet of the cold-carrying side of the evaporator 110 is connected to the working fluid pump 115 and the cold-carrying heat exchanger 116 in sequence. 6. The evaporator 110 includes two different fluid channels, namely, a refrigeration side fluid channel and an inlet and an outlet, and a cooling side fluid channel and an inlet and an outlet. The refrigeration side fluid channel and the cooling side fluid channel exchange heat through 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 110, and the cooling side fluid channel and the inlet and outlet inside the evaporator 110 flow The cooling agent component flows. After the outlet of the cooling heat exchanger 116 is connected to the stop valve 117, it is connected to the inlet and outlet of the liquid storage heat exchanger 113. The outlet of the liquid storage heat exchanger 113 is divided into two paths, one of which is connected to the low-pressure inlet of the ejector 112 through the stop valve 114, and the other is connected to the cooling side inlet of the evaporator 110.The liquid storage heat exchanger 113 is placed in the liquid storage tank 111.

[0025] Furthermore, the liquid storage heat exchanger 113 is connected to the interior of the liquid storage 111, the interior of the liquid storage heat exchanger 113 is used to flow the coolant, and the interior of the liquid storage 111 is used to flow the refrigerant. The inner cavity of the liquid storage heat exchanger 113 is not connected to the interior of the liquid storage 111, and no mass exchange occurs between the liquid storage heat exchanger 113 and the liquid storage 111. The liquid storage heat exchanger 113 is used to exchange heat with the liquid storage 111.

[0026] Furthermore, the control component includes a control module 201, a first temperature sensor 202, a component concentration sensor 203 and a second temperature sensor 204, the first temperature sensor 202 is connected to the evaporator 110, the second temperature sensor 204 is connected to the cooling heat exchanger 116, the component concentration sensor 203 is connected to the pipeline at the inlet end of the evaporator 110, the input end of the control module 201 is electrically connected to the first temperature sensor 202, the second temperature sensor 204 and the component concentration sensor 203, and the output end of the control module 201 is electrically connected to the compressor 101, the first expansion valve 104, the first ejector 105, the first stop valve 114, the second stop valve 117, the third stop valve 118, the second expansion valve 107, and the third expansion valve 109.

[0027] The present invention also provides a control method for an advanced environmentally friendly refrigeration system, comprising the following specific steps:

[0028] It includes a rated refrigeration temperature mode, the refrigeration temperature range is -20°C to -40°C, and the target rated refrigeration temperature is determined according to the predetermined refrigerant composition. When the rated refrigeration temperature mode is working, the first stop valve 114 is first closed, the second stop valve 117 is closed, the third stop valve 118 is closed, and the first expansion valve 104 is opened by 50%;

[0029] The control module 201 is connected to the first temperature sensor 202 to collect the outlet temperature of the refrigeration side of the evaporator 110. When the outlet temperature of the refrigeration side of the evaporator 110 is higher than the set rated refrigeration temperature, the opening of the second expansion valve 107 and the third expansion valve 109 is gradually reduced, and the speed of the compressor 101 is increased until the refrigeration load effect of the rated temperature is achieved. The speed of the compressor 101 is maintained unchanged, and the opening of the second expansion valve 107 and the third expansion valve 109 are maintained unchanged.

[0030] Including a low-temperature refrigeration mode, the refrigeration range is -80°C to -40°C, the refrigerant carbon dioxide in the refrigeration process is introduced into the refrigeration process, and a low-temperature refrigeration effect lower than the rated refrigeration temperature is achieved by increasing the low-temperature refrigerant component that participates in the circulation of the refrigeration process. When the low-temperature refrigeration mode is working, the first expansion valve 104 is opened 100%, the control module 201 is connected to the first temperature sensor 202 to collect the outlet temperature of the refrigeration side of the evaporator 110, the control module 201 is connected to the component concentration sensor 203 to collect the refrigerant component after the third expansion valve 109, and the control module 201 is connected to the second temperature sensor 204 to collect the outlet refrigerant temperature of the refrigeration heat exchanger 116. When the outlet refrigerant temperature of the refrigeration heat exchanger 116 is higher than or equal to the rated refrigeration temperature;

[0031] Open the third stop valve 118, open the first stop valve 114, close the second stop valve 117, gradually reduce the opening of the second expansion valve 107 and the third expansion valve 109, increase the speed of the compressor 101, when 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 116 reaches the set low-temperature refrigeration temperature, close the third stop valve 118, close the first stop valve 114, maintain the speed of the compressor 101 unchanged, and maintain the opening of the second expansion valve 107 and the third expansion valve 109 unchanged.

[0032] Including a high-temperature refrigeration mode, the refrigeration range is -20°C to 0°C, through the second ejector 112 and the liquid storage heat exchanger 113, the gaseous low-temperature refrigerant rich in carbon dioxide in the refrigeration process is extracted to the cold-carrying process, and the low-temperature refrigerant components participating in the circulation of the refrigeration process are reduced to achieve a refrigeration effect higher than the rated refrigeration temperature. 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 110, 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 outlet temperature of the cold-carrying heat exchanger 116;

[0033] When the outlet temperature of the refrigerant of the refrigerant heat exchanger 116 is lower than or equal to the rated refrigeration temperature, the second stop valve 117 is opened, the third stop valve 118 is closed, the first stop valve 114 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;

[0034] When the component concentration sensor 203 collects the carbon dioxide concentration in the refrigerant component after the third expansion valve 109 and it is lower than 1%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger 116 reaches the set high-temperature refrigeration temperature, the second stop valve 117 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.

[0035] 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. An advanced environmentally friendly refrigeration system, characterized in that: The invention comprises a compressor (101), a condenser (102), a first working fluid pump (103), a first expansion valve (104), a first ejector (105), a regenerator (106), a second expansion valve (107), a gas-liquid separator (108), a third expansion valve (109), an evaporator (110), a liquid storage device (111), a second ejector (112), a liquid storage heat exchanger (113), a first stop valve (114), a second working fluid pump (115), a cooling heat exchanger (116), a second stop valve (117), a third stop valve (118) and a control component, wherein the compressor The outlet of the working fluid pump (103) is connected to the condenser (102) and the working fluid pump (103) in sequence. The outlet of the working fluid pump (103) is connected to the expansion valve (104) and the high-temperature side inlet of the regenerator (106) in two ways respectively. The outlet of the expansion valve (104) is connected to the high-pressure inlet of the ejector (105). The high-temperature outlet of the regenerator (106) is connected to the expansion valve (107) and the inlet of the gas-liquid separator (108) in sequence. The gas phase outlet of the gas-liquid separator (108) is connected to the outlet of the ejector (105) and then connected to the low-temperature side inlet and outlet of the regenerator (106), the compressor (101) in sequence. ), the liquid phase outlet of the gas-liquid separator (108) is connected to the expansion valve (109), the refrigeration side inlet and outlet of the evaporator (110) in sequence, the gas phase outlet of the gas-liquid separator (108) is connected to the inlet of the stop valve (118), the outlet of the stop valve (118) is connected to the inlet of the liquid accumulator (111), the outlet of the liquid accumulator (111) is divided into two paths, one of which is connected to the high-pressure inlet of the ejector (112), the outlet of the ejector (112) is connected to the outlet of the expansion valve (109) and then to the refrigerant side inlet of the evaporator (110), and the other outlet of the liquid accumulator (111) is connected to the outlet of the expansion valve (109). One path is connected to the outlet of the cooling heat exchanger (116) via a stop valve (117); the outlet of the cooling side of the evaporator (110) is connected to the working fluid pump (115) and the cooling heat exchanger (116) in sequence; the outlet of the cooling heat exchanger (116) is connected to the stop valve (117) and then connected to the inlet and outlet of the liquid storage heat exchanger (113); the outlet of the liquid storage heat exchanger (113) is divided into two paths, one path is connected to the low-pressure inlet of the ejector (112) via a stop valve (114), and the other path is connected to the inlet of the cooling side of the evaporator (110); the liquid storage heat exchanger (113) is placed in the liquid storage (111).

2. The advanced environmentally friendly refrigeration system according to claim 1, characterized in that: The interior of the liquid storage heat exchanger (113) is used for flowing a coolant, and the interior of the liquid storage tank (111) is used for flowing a refrigerant. The inner cavity of the liquid storage heat exchanger (113) and the interior of the liquid storage tank (111) are not connected to each other, and the liquid storage heat exchanger (113) is used for heat exchange with the liquid storage tank (111).

3. The advanced environmentally friendly refrigeration system according to claim 1, characterized in that: The control component comprises: A first temperature sensor (202), the first temperature sensor (202) being connected to the evaporator (110); A second temperature sensor (204), the second temperature sensor (204) being connected to the cooling heat exchanger (116); A component concentration sensor (203), wherein the component concentration sensor (203) is connected to a pipeline at an inlet end of the evaporator (110); A control module (201), wherein an input end of the control module (201) is electrically connected to a first temperature sensor (202), a second temperature sensor (204) and a component concentration sensor (203), and an output end of the control module (201) is electrically connected to a compressor (101), a first expansion valve (104), a first ejector (105), a first stop valve (114), a second stop valve (117), a third stop valve (118), a second expansion valve (107), and a third expansion valve (109).

4. A control method for an advanced environmentally friendly refrigeration system according to any one of claims 1 to 3, characterized in that: The invention comprises a rated refrigeration temperature mode. When the rated refrigeration temperature mode is in operation, the first stop valve (114) is first closed, the second stop valve (117) is closed, the third stop valve (118) is closed, and the first expansion valve (104) is opened by 50%; The control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (110). When the outlet temperature of the refrigeration side of the evaporator (110) 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. 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.

5. The control method of an advanced environmentally friendly refrigeration system according to claim 4, characterized in that: The invention comprises a low-temperature refrigeration mode. When the low-temperature refrigeration mode is in operation, the first expansion valve (104) is opened 100%, the control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (110), 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 outlet temperature of the refrigerant of the refrigerant heat exchanger (116). When the outlet temperature of the refrigerant of the refrigerant heat exchanger (116) is higher than or equal to the rated refrigeration temperature; The third stop valve (118) is opened, the first stop valve (114) is opened, the second stop valve (117) is closed, 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. When 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 (116) reaches the set low-temperature refrigeration temperature, the third stop valve (118) is closed, the first stop valve (114) 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) are maintained unchanged.

6. The control method of an advanced environmentally friendly refrigeration system according to claim 4, characterized in that: The invention comprises a high-temperature refrigeration mode, wherein the first expansion valve (104) is opened by 50%, the control module (201) is connected to the first temperature sensor (202) to collect the outlet temperature of the refrigeration side of the evaporator (110), 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 outlet temperature of the refrigerant of the refrigerant heat exchanger (116); When the refrigerant temperature at the outlet of the refrigerant heat exchanger (116) is lower than or equal to the rated refrigeration temperature, the second stop valve (117) is opened, the third stop valve (118) is closed, the first stop valve (114) 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; When the component concentration sensor (203) collects the carbon dioxide concentration in the refrigerant component after the third expansion valve (109) and it is lower than 1%, and the refrigerant temperature at the outlet of the refrigerant heat exchanger (116) reaches the set high-temperature refrigeration temperature, the second stop valve (117) 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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