A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems

Abstract

The present invention provides a refrigeration unit capable of realizing switching operation between single-stage and two-stage compression refrigeration systems, comprising a No. 1 compressor, a No. 2 compressor, and at least a No. 3 compressor. The unit uses a single-stage compressor head, and controls the refrigerant piping system through which the refrigerant passes by the electric piston valve, thereby realizing switching between single-stage and two-stage compression systems, and meeting the evaporation temperature requirement of 5°C to 35°C, high temperature, medium temperature, and low temperature, and can be switched across temperature zones. By applying the technical solution of the present invention, a single unit using a single-stage compressor head can realize switching between single-stage compression and two-stage compression systems; and switch operation between high temperature, medium temperature, and low temperature operating conditions. This meets the needs of the unit in applications with different evaporation temperatures and improves the economy of system operation.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration units, in particular to a refrigeration unit capable of realizing switchable operation between single-stage and double-stage compression refrigeration systems. Background Art

[0002] In the existing field of refrigeration equipment, it is usually a single-stage compression system or a two-stage compression system. When the system operates at a lower evaporation temperature, the compression ratio of the compressor also increases, the volumetric efficiency of the compressor decreases, the irreversible loss of the compression process increases, the efficiency of the compressor decreases, and the cooling capacity and COP decrease significantly. The compressor exhaust temperature will also rise and may even exceed the maximum allowable value. In the single-stage refrigeration compression system of the domestic standard series compressor for fluorine, when the compression ratio exceeds 10, two-stage compression should be used. The cost of the two-stage compressor head used in the current two-stage compressor unit is usually higher than that of the single-stage compressor head. When the evaporation temperature changes, the two-stage compression system using the single-stage compressor head cannot be switched to a single-stage compression system. As a result, the current two-stage compressor unit has a high cost and the economic efficiency of the unit operation under special working conditions needs to be improved. Summary of the Invention

[0003] In view of the above problems existing in the current two-stage compressor unit and in response to the application scenarios of the unit at different evaporation temperatures, the present invention provides a refrigeration unit that can realize switchable operation between single-stage and two-stage compression refrigeration systems.

[0004] The technical means adopted in the present invention are as follows:

[0005] A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems, comprising a No. 1 compressor unit, the No. 1 compressor unit including a No. 1 compressor, the suction end of the No. 1 compressor being connected to an intermediate-pressure-stage gas-liquid separation assembly, the intermediate-pressure-stage exhaust manifold assembly being connected to the intermediate-pressure gas-liquid separation assembly, the exhaust end of the No. 1 compressor being connected to a high-pressure-stage exhaust manifold assembly, and further comprising a low-pressure-stage gas-liquid separation assembly and a No. 2 compressor unit;

[0006] The No. 2 compressor unit includes the No. 2 compressor, the No. 2 exhaust check valve and the No. 2 exhaust valve. The suction end of the No. 2 compressor is connected to the low-pressure stage gas-liquid separator assembly, and the exhaust end is connected to the high-pressure stage exhaust manifold assembly through the No. 2 exhaust check valve and to the intermediate-pressure stage exhaust manifold assembly through the No. 2 exhaust valve; the low-pressure stage gas-liquid separator assembly is connected to the intermediate-pressure stage gas-liquid separation assembly through the refrigerant bypass check valve.

[0007] Preferably, at least one No. 3 compressor unit is further included, and the number of No. 3 compressor units can be one or more units as needed. The No. 3 compressor unit includes a No. 3 compressor, a No. 3 exhaust check valve, a No. 3 exhaust valve, a No. 3 intake valve, and a No. 3 intake check valve; the intake end of the No. 3 compressor is connected to the intermediate pressure stage gas-liquid separator assembly via the No. 3 intake valve, and is connected to the low pressure stage gas-liquid separator assembly via the No. 3 intake check valve; the exhaust end of the No. 3 compressor is connected to the high pressure stage exhaust manifold assembly via the No. 3 exhaust check valve, and is connected to the intermediate pressure stage exhaust manifold assembly via the No. 3 exhaust valve.

[0008] Preferably, the No. 2 exhaust valve, the No. 3 exhaust valve and the No. 3 intake valve all adopt electric piston valves; all the above-mentioned one-way valves are normally open valves.

[0009] Preferably, the high-pressure exhaust manifold assembly is connected to a water-cooled condenser assembly. The water-cooled condenser assembly is used to condense the exhaust gas in the high-pressure exhaust manifold assembly into condensed liquid; the high-pressure exhaust manifold assembly is connected to the water-cooled condenser assembly via an oil separator module. The oil separator module is used to separate the oil in the high-pressure exhaust manifold assembly. The water-cooled condenser assembly is connected to the economizer via a liquid supply line filter. The condensed liquid in the water-cooled condenser assembly enters the economizer in two ways, wherein the second condensed liquid is supercooled by the first condensed liquid, and the generated gas enters the intermediate-pressure exhaust manifold assembly and mixes with the gas in the intermediate-pressure exhaust manifold assembly.

[0010] Preferably, the liquid outlet of the economizer is connected to the evaporator, and the evaporator is connected to the low-pressure gas-liquid separator assembly through the low-pressure gas-liquid separator inlet filter.

[0011] Preferably, the liquid outlet of the economizer is connected to the low-pressure gas-liquid separator assembly via a liquid intake pipe, a solenoid valve disposed on the liquid intake pipe, and the aforementioned low-pressure gas-liquid separator inlet filter. A liquid injection expansion valve assembly is disposed within the liquid intake pipe, and a temperature-sensing bulb of the liquid injection expansion valve assembly is disposed within the high-pressure exhaust manifold assembly. When the temperature-sensing bulb senses that the temperature within the high-pressure exhaust manifold assembly exceeds the set temperature of the liquid injection expansion valve assembly, the liquid injection expansion valve assembly opens.

[0012] Preferably, the intermediate-pressure stage exhaust manifold assembly is connected to the intermediate-pressure stage gas-liquid separator assembly through an intermediate-pressure stage gas-liquid separator inlet filter.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. This unit is equipped with a No. 2 exhaust electric piston valve at the exhaust end of the No. 2 compressor, a No. 3 exhaust electric piston valve at the exhaust end of the No. 3 compressor, and a No. 3 suction electric piston valve at the intake end. By adjusting the opening and closing of each of the above electric piston valves, the refrigerant piping system through which the refrigerant flows can be controlled, thereby realizing the switching of the compression system between single-stage compression and two-stage compression to correspond to a wider range of evaporation temperatures, thereby improving the economy of the unit operation.

[0015] 2. As the demand for cooling capacity increases, the number of No. 3 compressor units can be increased to meet different cooling capacity requirements.

[0016] 3. The compressors used in the present invention are all single-stage compressors, and can realize switching between single-stage and two-stage compression systems, meeting the evaporation temperature from 5°C to -35°C high temperature, medium temperature, and low temperature and can switch across temperature zones.

[0017] Based on the above reasons, the present invention can be widely promoted in the fields of refrigeration units and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 The figure is a schematic diagram of the structural connection of a refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems in a specific embodiment of the present invention.

[0020] In the figure: 1. High-pressure stage exhaust manifold assembly; 2. Intermediate-pressure stage exhaust manifold assembly; 3. Intermediate-pressure stage gas-liquid separator assembly; 4. Low-pressure stage gas-liquid separator assembly; 5. Compressor No. 1; 6. Compressor No. 2; 7. Exhaust check valve No. 2; 8. Exhaust electric piston valve No. 2; 9. Compressor No. 3; 10. Exhaust check valve No. 3; 11. Exhaust electric piston valve No. 3; 12. Intake electric piston valve No. 3; 13. Intake check valve No. 3; 14. Oil separator module; 15. Water-cooled condenser assembly; 16. Liquid supply line filter; 17. Economizer; 18. Solenoid valve; 19. Low-pressure stage gas-liquid separator inlet filter; 20. Liquid injection expansion valve assembly; 21. Intermediate-pressure stage gas-liquid separator inlet filter; 22. Refrigerant bypass check valve; 23. Evaporator. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0024] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0025] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0026] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0027] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0028] like Figure 1 As shown, a refrigeration unit capable of realizing switchable operation of a single-stage and two-stage compression refrigeration system includes a No. 1 compressor unit, the No. 1 compressor unit includes a No. 1 compressor 5, the suction end of the No. 1 compressor 5 is connected to the intermediate pressure stage gas-liquid separation component 3, the intermediate pressure stage exhaust manifold assembly 2 is connected to the intermediate pressure stage gas-liquid separation component 3, the exhaust end of the No. 1 compressor 5 is connected to the high-pressure stage exhaust manifold assembly 1, and further includes a low-pressure stage gas-liquid separation component 4 and a No. 2 compressor unit;

[0029] The No. 2 compressor unit includes the No. 2 compressor 6, the No. 2 exhaust check valve 7 and the No. 2 exhaust electric piston valve 8. The suction end of the No. 2 compressor 6 is connected to the low-pressure stage gas-liquid separator assembly 4, and the exhaust end is connected to the high-pressure stage exhaust manifold assembly 1 through the No. 2 exhaust check valve 7 and to the intermediate-pressure stage exhaust manifold assembly 2 through the No. 2 exhaust electric piston valve 8; the low-pressure stage gas-liquid separator assembly 4 is connected to the intermediate-pressure stage gas-liquid separation assembly 3 through the refrigerant bypass check valve 22.

[0030] In this embodiment, when the No. 2 exhaust electric piston valve 8 is opened, the suction end of the No. 2 compressor 6 inhales the low-pressure gas in the low-pressure gas-liquid separator assembly 4, and then enters the intermediate-pressure exhaust manifold assembly 2 through the exhaust end of the No. 2 compressor 6 and the No. 2 exhaust electric piston valve 8, and then enters the intermediate-pressure gas-liquid separation assembly 3 for gas-liquid separation. The suction end of the No. 1 compressor 5 inhales the intermediate-pressure gas in the intermediate-pressure gas-liquid separation assembly 3, and then discharges the high-pressure gas into the high-pressure exhaust manifold assembly 1, forming a two-stage compression. When the No. 2 exhaust electric piston valve 8 is open, the pressure in the high-pressure exhaust manifold assembly 1 is higher than the pressure at the exhaust end of the No. 2 compressor 6, and the No. 2 exhaust check valve 7 cannot circulate. Moreover, because it is a one-way valve, the high-pressure gas in the high-pressure exhaust manifold assembly 1 cannot enter the exhaust end of the No. 2 compressor 6. When the No. 2 exhaust electric piston valve 8 is closed, the No. 2 compressor 6 inhales the low-pressure gas in the low-pressure gas-liquid separator assembly 4, and then enters the high-pressure exhaust manifold assembly 1 through the exhaust end of the No. 2 compressor 6 and the No. 2 exhaust one-way valve 7. At this time, there is no medium-pressure gas in the intermediate-pressure gas-liquid separation assembly 3, and the low-pressure gas in the low-pressure gas-liquid separator assembly 4 enters the intermediate-pressure gas-liquid separation assembly 3 through the refrigerant bypass one-way valve 22 for inhalation by the No. 1 compressor, and enters the high-pressure exhaust manifold assembly 1 through the exhaust end of the No. 1 compressor 5 to form a single-stage compression.

[0031] A refrigeration unit that can realize switching operation between single-stage and two-stage compression refrigeration systems also includes at least one No. 3 compressor unit (two are used in this specific embodiment), and the No. 3 compressor unit includes a No. 3 compressor 9, a No. 3 exhaust check valve 10, a No. 3 exhaust electric piston valve 11, a No. 3 intake electric piston valve 12 and a No. 3 intake check valve 13; the intake end of the No. 3 compressor 9 is connected to the intermediate pressure stage gas-liquid separator assembly 3 through the No. 3 intake electric piston valve 12, and is connected to the low pressure stage gas-liquid separator assembly 4 through the No. 3 intake check valve 13; the exhaust end of the No. 3 compressor 9 is connected to the high pressure stage exhaust manifold assembly 1 through the No. 3 exhaust check valve 10, and is connected to the intermediate pressure stage exhaust manifold assembly 2 through the No. 3 exhaust electric piston valve 11.

[0032] The gas inhaled by the No. 3 compressor 9 can be the low-pressure gas in the low-pressure gas-liquid separation component 4 or the medium-pressure gas in the intermediate-pressure gas-liquid separation component 3, and the discharged gas can be selected to enter the intermediate-pressure exhaust pipe component 2 or the high-pressure exhaust manifold component 1.

[0033] The intermediate-pressure stage exhaust manifold assembly 2 is connected to the intermediate-pressure stage gas-liquid separator assembly 3 through the intermediate-pressure stage gas-liquid separator inlet filter 21 .

[0034] The high-pressure exhaust manifold assembly 1 is connected to the water-cooled condenser assembly 15 via the oil separator module 14. The water-cooled condenser assembly 15 is connected to the economizer 17 via the liquid supply line filter 16. The water-cooled condenser assembly 15 is used to condense the exhaust gas in the high-pressure exhaust manifold assembly 1 into condensed liquid; the oil separator module 14 is used to separate the oil in the high-pressure exhaust manifold assembly 15. The condensed liquid in the water-cooled condenser assembly 15 enters the economizer 17 in two ways, where the second condensed liquid is used to supercool the first condensed liquid. The generated gas enters the intermediate-pressure exhaust manifold assembly 2 and mixes with the gas in the intermediate-pressure exhaust manifold assembly 2. The high-pressure exhaust gas in the high-pressure exhaust manifold assembly 1 is rationally utilized to convert it into intermediate-level exhaust gas and enter the intermediate-pressure exhaust pipe assembly 2.

[0035] The liquid outlet of the economizer 17 is connected to the evaporator 23 , and the evaporator 23 is connected to the low-pressure gas-liquid separator assembly 4 through the low-pressure gas-liquid separator inlet filter 19 .

[0036] The liquid outlet of the economizer 17 is also connected to the low-pressure gas-liquid separator assembly 4 via a liquid intake pipe, a solenoid valve 18 mounted on the pipe, and a low-pressure gas-liquid separator inlet filter 19. A liquid injection expansion valve assembly 20 is installed within the liquid intake pipe. The temperature sensor for the liquid injection expansion valve assembly 20 is located within the high-pressure exhaust manifold assembly 1 and connected to the temperature sensor via a temperature sensing pipe. When the temperature sensor senses that the temperature within the high-pressure exhaust manifold assembly 1 exceeds the set temperature of the liquid injection expansion valve assembly 20, the liquid injection expansion valve assembly 20 opens. When the temperature within the high-pressure exhaust manifold assembly 1 exceeds the set value of the liquid injection expansion valve assembly 20, the liquid injection expansion valve assembly 20 opens, causing the solenoid valve 18 to open. Liquid in the liquid intake pipe mixes with the low-pressure gas flowing from the evaporator 23, cooling the low-pressure gas. This lowers the temperature within the low-pressure gas-liquid separator assembly 4, and consequently, the temperature within the high-pressure exhaust manifold assembly 1.

[0037] When the refrigeration unit in this embodiment is in a single-stage compression working state, the No. 2 exhaust electric piston valve 8, the No. 3 exhaust electric piston valve 11, and the No. 3 intake electric piston valve 12 are in a closed state. At this time, the exhaust gases of the four compressors are all discharged into the high-pressure stage exhaust manifold assembly 1. The inhaled gas is all low-pressure gas (although the gas inhaled by compressor No. 1 is the gas in the intermediate-pressure-stage gas-liquid separation assembly 3, the gas in the intermediate-pressure-stage gas-liquid separation assembly 3 is the gas flowing into the low-pressure-stage gas-liquid separator assembly 4, and is also low-pressure gas). The refrigerant gas enters the water-cooled condenser assembly 15 through the oil separation module 14, and the condensed refrigerant liquid enters the economizer 17 through the liquid supply pipeline filter 16. At this time, it is a single-stage compression, the solenoid valve in the economizer 17 is in a closed state, the thermal expansion valve does not work, and the refrigerant liquid enters the external evaporator 23. After evaporation, the refrigerant gas enters the low-pressure-stage gas-liquid separator assembly 4 through the low-pressure-stage gas-liquid separator inlet filter 19 and is inhaled by compressor No. 2 6 and compressor No. 3 9. Due to the presence of the refrigerant bypass one-way valve 22, the pressure in the low-pressure-stage gas-liquid separator assembly 4 is always lower than the pressure in the intermediate-pressure-stage gas-liquid separator assembly 3. Compressor No. 1 inhales air from the intermediate-pressure-stage gas-liquid separator assembly 3, thereby completing the entire refrigeration cycle.

[0038] When the refrigeration unit in this embodiment is in a two-stage compression state with one high-pressure compressor and three low-pressure compressors, the No. 2 exhaust electric piston valve 8 and the No. 3 exhaust electric piston valve 11 are in the open state, and the No. 3 suction electric piston valve 12 is in the closed state. At this time, the exhaust of the No. 2 compressor 6 and the No. 3 compressor 9 can enter the 102 intermediate pressure stage exhaust manifold assembly 2 through the No. 2 exhaust electric piston valve 8 and the No. 3 exhaust electric piston valve 11, and can also enter the high pressure stage exhaust manifold assembly 1 through the No. 2 exhaust check valve 7 and the No. 3 exhaust check valve 10. However, after one cycle, the No. 1 compressor 5 The exhaust gas enters the high-pressure stage exhaust manifold assembly 1. This pressure is higher than the pressure before the valves of the No. 2 exhaust check valve 7 and the No. 3 exhaust check valve 10. Due to the one-way passage function of the check valve, the exhaust gas of the No. 2 compressor 6 and the No. 3 compressor 9 can only enter the intermediate-pressure stage exhaust manifold assembly 2 through the No. 2 exhaust electric piston valve 8 and the No. 3 exhaust electric piston valve 11, and then enter the intermediate-pressure stage gas-liquid separator assembly 3 through the intermediate-pressure stage gas-liquid separator inlet filter 21, and is sucked into the No. 1 compressor 5 to complete the two-stage compression and enter the high-efficiency oil separation module 14. The refrigerant flow direction before suction is the same as the above process. The difference is that the solenoid valve in the economizer 17 is opened, and the thermal expansion valve works to supercool the refrigerant liquid. When the refrigerant gas returns to the low-pressure stage gas-liquid separator assembly 4, it is sucked into the No. 2 compressor 6 and the No. 3 compressor 9 to complete the refrigeration cycle.

[0039] When the refrigeration unit of this embodiment is in a two-stage compression process with two high-pressure stages and two low-pressure stages, compressor No. 1 5 always serves as the high-pressure stage, compressor No. 2 6 serves as the low-pressure stage, one of the two compressors No. 3 9 serves as the low-pressure stage, and the other serves as the high-pressure stage. The No. 3 exhaust electric piston valve 11 of one of the compressors is in a closed state, and the No. 3 suction electric piston valve 12 is in an open state, and the other No. 3 exhaust electric piston valve 11 is in an open state, and the No. 3 suction electric piston valve 12 is in a closed state; and the No. 2 exhaust electric piston valve 8 is in an open state; at this time, the exhaust of compressor No. 1 5 and one of the compressors No. 3 (the compressor No. 3 with its No. 3 exhaust electric piston valve 11 closed) enters the high-pressure stage exhaust manifold assembly 1, and the exhaust of the other compressor No. 3 9 and compressor No. 2 6 enters the intermediate-pressure stage exhaust manifold assembly 2, and then enters the intermediate-pressure stage gas-liquid separator assembly 3 through the intermediate-pressure stage gas-liquid separator inlet filter 21, and is sucked in by compressor No. 1 5 and compressor No. 3 9 (the compressor No. 3 with its No. 3 exhaust electric piston valve 11 closed).

[0040] Since the pressure in the intermediate pressure stage gas-liquid separator assembly 3 is always higher than the pressure in the low pressure stage gas-liquid separator assembly 4, the pressure in front of the No. 3 suction check valve 13 is always greater than the pressure in the low pressure stage gas-liquid separator assembly 4, ensuring that the suction of the No. 3 compressor 9 is only sucked into the compression from the intermediate pressure stage gas-liquid separator assembly 3 to complete the two-stage compression.

[0041] Therefore, according to an embodiment of the present invention, a No. 2 exhaust electric piston valve 8 is provided at the exhaust end of the No. 2 compressor 6, a No. 3 exhaust electric piston valve 11 is provided at the exhaust end of the No. 3 compressor 9, and a No. 3 intake electric piston valve 12 is provided at the intake end. By adjusting the opening and closing of each of the above-mentioned electric piston valves, the refrigerant piping system through which the refrigerant flows can be controlled, thereby realizing the switching of the compression system between single-stage compression or two-stage compression to correspond to a wider range of evaporation temperatures, and the economy of the unit operation is improved.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems, comprising a No. 1 compressor unit, wherein the No. 1 compressor unit comprises a No. 1 compressor, wherein the suction end of the No. 1 compressor is connected to an intermediate pressure stage gas-liquid separation assembly, the intermediate pressure stage exhaust manifold assembly is connected to the intermediate pressure stage gas-liquid separation assembly, and the exhaust end of the No. 1 compressor is connected to a high pressure stage exhaust manifold assembly, characterized in that: Also included are the low-pressure stage gas-liquid separation assembly and the No. 2 compressor unit; The No. 2 compressor unit includes a No. 2 compressor, a No. 2 exhaust check valve and a No. 2 exhaust valve. The suction end of the No. 2 compressor is connected to the low-pressure stage gas-liquid separator assembly, and the exhaust end is connected to the high-pressure stage exhaust manifold assembly through the No. 2 exhaust check valve and to the intermediate-pressure stage exhaust manifold assembly through the No. 2 exhaust valve. The low-pressure gas-liquid separator assembly is connected to the intermediate-pressure gas-liquid separator assembly via a refrigerant bypass one-way valve; When the No. 2 exhaust valve is opened, the exhaust end of the No. 2 compressor is connected to the intermediate pressure stage exhaust manifold assembly, forming a two-stage compression; when the No. 2 exhaust valve is closed, the exhaust end of the No. 2 compressor is connected to the high pressure stage exhaust manifold assembly through the No. 2 exhaust check valve, and at the same time, the refrigerant in the low pressure stage gas-liquid separator assembly enters the intermediate pressure stage gas-liquid separation assembly through the refrigerant bypass check valve, forming a single-stage compression; the unit achieves cross-temperature operation with an evaporation temperature ranging from 5°C to -35°C by switching between single-stage compression and two-stage compression modes; The system further comprises at least one No. 3 compressor unit, the No. 3 compressor unit comprising a No. 3 compressor, a No. 3 exhaust check valve, a No. 3 exhaust valve, a No. 3 suction valve and a No. 3 suction check valve; the suction end of the No. 3 compressor is connected to the intermediate-pressure-stage gas-liquid separator assembly via the No. 3 suction valve, and is connected to the low-pressure-stage gas-liquid separator assembly via the No. 3 suction check valve; the discharge end of the No. 3 compressor is connected to the high-pressure-stage exhaust manifold assembly via the No. 3 exhaust check valve, and is connected to the intermediate-pressure-stage exhaust manifold assembly via the No. 3 exhaust valve; The high-pressure stage exhaust manifold assembly is connected to a water-cooled condenser assembly, which is connected to an economizer. The condensed liquid in the water-cooled condenser assembly enters the economizer in two ways, wherein the second condensed liquid is used to supercool the first condensed liquid, and the generated gas enters the intermediate-pressure stage exhaust manifold assembly and mixes with the gas in the intermediate-pressure stage exhaust manifold assembly. The No. 2 exhaust valve, the No. 3 exhaust valve and the No. 3 intake valve are all electric piston valves.

2. A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 1, characterized in that: The high-pressure exhaust manifold assembly is connected to the water-cooled condenser assembly through an oil separation module.

3. The refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 1, characterized in that: The water-cooled condenser assembly is connected to the economizer through a liquid supply line filter.

4. The refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 1, characterized in that: The liquid outlet of the economizer is connected to the evaporator, and the evaporator is connected to the low-pressure gas-liquid separator component through a low-pressure gas-liquid separator inlet filter.

5. A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 4, characterized in that: The liquid outlet of the economizer is connected to the low-pressure gas-liquid separator assembly through a liquid extraction pipe, a solenoid valve arranged on the liquid extraction pipe, and an inlet filter of the low-pressure gas-liquid separator.

6. A refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 5, characterized in that: A liquid injection expansion valve assembly is provided in the liquid intake pipe, and a temperature sensing package of the liquid injection expansion valve assembly is provided in the high-pressure exhaust manifold assembly. When the temperature sensing package senses that the temperature in the high-pressure exhaust manifold assembly exceeds the set temperature of the liquid injection expansion valve assembly, the liquid injection expansion valve assembly opens.

7. The refrigeration unit capable of switching between single-stage and two-stage compression refrigeration systems according to claim 1, characterized in that: The intermediate-pressure-stage exhaust manifold assembly is connected to the intermediate-pressure-stage gas-liquid separator assembly through an intermediate-pressure-stage gas-liquid separator inlet filter.

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