A large-elevation gravity liquid-supplied refrigeration system and working method thereof

Abstract

The application provides a large-height-difference gravity liquid supply refrigeration system and a working method thereof, and relates to the technical field of refrigeration systems.The system comprises a refrigeration compressor, an oil separator, a condenser, a first liquid accumulator, an electric regulating valve, a gas-liquid separator, a heat exchanger, a second liquid accumulator, a stop valve, a filter, a liquid supply electromagnetic valve, an electric regulating valve, an evaporator, a sensor stop valve, a sensor, a micro gas-liquid separator, a stop valve, a one-way stop valve and a liquid level switch.The application can effectively reduce the energy consumption caused by the pump liquid supply mode of the traditional large-height-difference refrigeration system and the problem of excessive refrigerant charging caused by multiple liquid supply, is beneficial to energy saving and emission reduction, can solve the influence of the static liquid column of the large-height-difference gravity liquid supply system on the heat exchange of the evaporator, the refrigeration terminal adopts oil-free cold carrier mode, the heat exchange efficiency of the evaporator can not be affected by the oil film, in addition, the system adopts gravity liquid supply, the machine room can be arranged on the roof without occupying the warehouse volume, and the warehouse capacity can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of refrigeration system technology, and more particularly to a gravity-fed refrigeration system with a large elevation difference and its working method. Background Technology

[0002] Large-elevation-difference liquid supply refrigeration systems refer to refrigeration systems where the elevation difference between the evaporator and the refrigeration unit exceeds 15 meters. For this type of refrigeration, current designs commonly employ multi-pump circulation liquid supply to ensure stable terminal liquid supply. However, this method increases energy consumption due to the added circulation pumps, and the multi-pump liquid supply also requires a large refrigerant charge to ensure system operation. The new cold storage design standard emphasizes minimizing refrigerant charge in refrigeration system design. Therefore, adapting gravity liquid supply to large-elevation-difference liquid supply systems presents significant challenges. However, ensuring terminal liquid level control, maintaining evaporator heat exchange efficiency, and addressing issues like liquid carryover during return flow remain major hurdles in promoting gravity liquid supply.

[0003] In summary, this invention designs a gravity-fed refrigerant supply refrigeration system with a large elevation difference and its working method, ensuring the refrigerant level at the terminal and the heat exchange effect of the evaporator. Summary of the Invention

[0004] To address the aforementioned technical problems encountered when adapting existing gravity-fed liquid supply methods to large elevation difference liquid supply systems, such as the inability to guarantee terminal liquid level control, evaporator heat exchange efficiency, and liquid carryover during gas return, this invention provides a large elevation difference gravity-fed liquid supply refrigeration system and its operating method. The refrigeration system of this invention employs an oil-free terminal cooling method, ensuring that the evaporator heat exchange efficiency is unaffected by the oil film. Furthermore, by using gravity-fed liquid supply, the machine room can be installed on the roof without occupying warehouse space, effectively increasing warehouse capacity.

[0005] The technical means employed in this invention are as follows:

[0006] A gravity-fed refrigeration system with a large elevation difference includes a refrigeration compressor. The suction port of the refrigeration compressor is connected to the outlet of a gas-liquid separator. The discharge port of the refrigeration compressor is connected to the inlet of an oil separator. The discharge port of the oil separator is connected to the inlet of a condenser. The liquid outlet of the condenser is connected to the inlet of a first liquid receiver. The liquid outlet of the first liquid receiver is connected to the inlet of the gas-liquid separator. The liquid outlet of the gas-liquid separator is connected to the inlet of a first refrigerant in a heat exchanger. The gas outlet of the first refrigerant in the heat exchanger is connected to... The inlet of the gas-liquid separator is connected to the inlet and outlet of the second refrigerant of the heat exchanger, which are respectively connected to the outlet and inlet of the second liquid receiver. The outlet of the second liquid receiver is connected to the liquid supply port of the evaporator through a first pipe. The return port of the evaporator is connected to the miniature gas-liquid separator through a second pipe. The outlet of the miniature gas-liquid separator is connected to the inlet of the second liquid receiver through a third pipe. The outlet of the miniature gas-liquid separator is connected to one end of a one-way shut-off valve, and the other end of the one-way shut-off valve is connected to the first pipe.

[0007] Furthermore, a first shut-off valve, a filter, a liquid supply solenoid valve, and an electric regulating valve are sequentially installed on the first pipeline.

[0008] Furthermore, a sensor is installed on the second pipeline, and a sensor shut-off valve is connected below the sensor.

[0009] Furthermore, the outlet of the first liquid reservoir is connected to the inlet of the gas-liquid separator via a pipe, and an electric regulating valve for liquid supply is provided at the end of the pipe.

[0010] Furthermore, a liquid level switch is installed on the miniature gas-liquid separator.

[0011] Furthermore, the one-way shut-off valve is connected to the first pipe between the electric regulating valve and the evaporator.

[0012] Furthermore, a second shut-off valve is installed on the third pipeline.

[0013] The present invention also provides a method for operating a gravity-fed refrigeration system with a large elevation difference, comprising the following steps:

[0014] During operation, the gaseous second refrigerant from the terminal evaporator in the cold room is separated by the second liquid receiver and enters the heat exchanger to exchange heat with the liquid first refrigerant. The second refrigerant is condensed from a gaseous state into a liquid state and enters the second liquid receiver, while the first refrigerant is converted from a liquid state back to a gaseous state and returns to the gas-liquid separator. The first refrigerant in the gas-liquid separator is drawn and compressed by the compressor and discharged into the oil separator, and then enters the condenser. In the condenser, the first refrigerant is converted from a gaseous state into a liquid state and flows into the first liquid receiver. The first refrigerant in the first liquid receiver flows through the liquid supply electric regulating valve into the gas-liquid separator according to the liquid level requirement of the gas-liquid separator in the condenser-evaporator skid, and then flows into the heat exchanger to exchange heat with the second refrigerant.

[0015] The second refrigerant from the second liquid receiver in the computer room enters the evaporator through the liquid supply line; in the evaporator, the second refrigerant changes from liquid to gas through heat exchange with the outside; the gaseous second refrigerant enters the micro gas-liquid separator through the evaporator return port, and then enters the second liquid receiver in the computer room for separation before entering the heat exchanger to exchange heat with the first refrigerant; during the evaporator cooling process, the electric regulating valve can adjust its opening degree according to the information fed back to the system by the return gas end sensor to ensure stable liquid supply to the evaporator and a zero superheated vapor state in the return gas.

[0016] Furthermore, a liquid level switch is installed on the miniature gas-liquid separator. When the refrigerant level in the miniature gas-liquid separator reaches the level of the liquid level switch, the liquid level switch will send a feedback signal to the liquid supply solenoid valve and close the liquid supply solenoid valve. After the liquid supply solenoid valve is closed, when the evaporator is cooling normally, the liquid refrigerant in the miniature gas-liquid separator can enter the evaporator through the liquid outlet to participate in the cyclic refrigeration. When the refrigerant level reaches below the safe level, a feedback signal can be sent and the liquid supply solenoid valve can be opened to ensure the liquid supply of the system.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention installs an electric regulating valve for liquid supply at the liquid supply port of the evaporator and a return gas sensor near the return gas port of the evaporator. The return gas sensor controls the opening degree of the electric regulating valve for liquid supply in the evaporator, which can ensure that the return gas of the system is in a zero superheat state, avoid a large amount of liquid in the return gas, and improve the system energy efficiency.

[0019] 2. This invention installs a miniature gas-liquid separator and a liquid level switch at the evaporator return gas port. When liquid refrigerant inevitably appears in the system return gas pipeline, it can be separated in the miniature gas-liquid separator, further solving the problem of liquid carryover in the return gas. Furthermore, by connecting a one-way shut-off valve between the liquid outlet of the miniature gas-liquid separator and the liquid inlet of the evaporator, refrigerant is prevented from flowing back to the miniature gas-liquid separator, ensuring the stability and safety of the system operation.

[0020] 3. While ensuring stable operation of the refrigeration system using gravity-fed liquid supply, this invention effectively reduces the energy consumption caused by pump-fed liquid supply in traditional high-elevation-difference refrigeration systems and the problem of excessive refrigerant charge due to multiple liquid supply, which is beneficial for energy conservation and emission reduction. It can also solve the problem of the static liquid column affecting the heat exchange of the evaporator in high-elevation-difference gravity-fed liquid supply systems. Furthermore, the refrigeration terminal adopts an oil-free cooling method, so the heat exchange efficiency of the evaporator is not affected by the oil film. In addition, since the system uses gravity-fed liquid supply, the machine room can be set on the roof without occupying warehouse volume, which can effectively increase the warehouse capacity.

[0021] 4. This invention has strong application prospects in cold storage projects with large elevation differences. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall system of the present invention.

[0024] In the diagram: 1. Refrigeration compressor; 2. Oil separator; 3. Condenser; 4. First liquid receiver; 5. Electric liquid supply regulating valve; 6. Gas-liquid separator; 7. Heat exchanger; 8. Second liquid receiver; 9. First shut-off valve; 10. Filter; 11. Liquid supply solenoid valve; 12. Electric regulating valve; 13. Evaporator; 14. Sensor shut-off valve; 15. Sensor; 16. Miniature gas-liquid separator; 17. Second shut-off valve; 18. One-way shut-off valve; 19. Liquid level switch. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0029] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0030] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0032] like Figure 1 As shown, this invention provides a gravity-fed liquid refrigeration system with a large elevation difference, including a refrigeration compressor 1. The suction port of the refrigeration compressor 1 is connected to the outlet port of a gas-liquid separator 6, the discharge port of the refrigeration compressor 1 is connected to the inlet port of an oil separator 2, the discharge port of the oil separator 2 is connected to the inlet port of a condenser 3, the liquid outlet port of the condenser 3 is connected to the inlet port of a first liquid receiver 4, the liquid outlet port of the first liquid receiver 4 is connected to the inlet port of the gas-liquid separator 6, the liquid outlet port of the gas-liquid separator 6 is connected to the inlet port of a first refrigerant in a heat exchanger 7, and the gas outlet port of the first refrigerant in the heat exchanger 7 is connected to the inlet port of the gas-liquid separator 6. The second refrigerant outlet port of the heat exchanger 7 is connected to the inlet port of the gas-liquid separator 6. The refrigerant inlet and outlet are connected to the outlet and inlet of the second liquid receiver 8, respectively. The outlet of the second liquid receiver 8 is connected to one end of the evaporator 13 through a first pipe. The other end of the evaporator 13 is connected to the miniature gas-liquid separator 16 through a second pipe. A liquid level switch 19 is installed on the miniature gas-liquid separator 16. The outlet of the miniature gas-liquid separator 16 is connected to the inlet of the second liquid receiver (which also serves as a gas-liquid separator) 8 through a third pipe. The outlet of the miniature gas-liquid separator 16 is connected to one end of a one-way shut-off valve 18. The other end of the one-way shut-off valve 18 is connected to the first pipe between the electric regulating valve 12 and the evaporator 13.

[0033] The first pipeline is sequentially equipped with a first shut-off valve 9, a filter 10, a liquid supply solenoid valve 11, and an electric regulating valve 12.

[0034] A sensor 15 is installed on the second pipeline, and a sensor shut-off valve 14 is connected below the sensor 15.

[0035] The outlet of the first liquid reservoir 4 is connected to the inlet of the gas-liquid separator 6 via a pipe, and an electric regulating valve 5 for liquid supply is provided at the end of the pipe.

[0036] The present invention also includes a method for operating a gravity-fed refrigeration system with a large elevation difference, comprising a refrigeration unit in the machine room, a condenser-evaporator skid, and a condenser installed on the roof of the cold storage; and refrigeration equipment in the cold room. The refrigeration unit in the machine room includes a refrigeration compressor 1 and an oil separator 2; the condenser-evaporator skid includes a liquid supply electric regulating valve 5, a gas-liquid separator 6, a heat exchanger 7, and a second liquid receiver 8; and the refrigeration equipment in the cold room includes an evaporator 13 and a miniature gas-liquid separator 16.

[0037] During operation, the gaseous second refrigerant from the evaporator 13 at the end of the cold room is separated by the second liquid receiver (which also acts as a gas-liquid separator) 8 and enters the heat exchanger 7 to exchange heat with the liquid first refrigerant. The second refrigerant is condensed from a gaseous state into a liquid state and enters the second liquid receiver 8. The first refrigerant is converted from a liquid state to a gaseous state and returns to the gas-liquid separator 6. The first refrigerant in the gas-liquid separator 6 is drawn and compressed by the compressor 1 and discharged into the oil separator 2, and then enters the condenser 3. In the condenser 3, the first refrigerant is converted from a gaseous state into a liquid state and flows into the first liquid receiver 4. The first refrigerant in the first liquid receiver 4 flows through the liquid supply electric regulating valve 5 into the gas-liquid separator 6 according to the liquid level requirement of the gas-liquid separator 6 in the condenser-evaporator skid, and then flows into the heat exchanger 7 to exchange heat with the second refrigerant.

[0038] The second refrigerant from the second liquid receiver 8 in the computer room enters the evaporator 13 through the liquid supply pipeline; in the evaporator 13, the second refrigerant changes from liquid to gas through heat exchange with the outside; the gaseous second refrigerant enters the micro gas-liquid separator 16 through the gas return port of the evaporator 13, and then enters the second liquid receiver 8 (which also serves as a gas-liquid separator) in the computer room for separation before entering the heat exchanger 7 to exchange heat with the first refrigerant; during the cooling process of the evaporator 13, the electric regulating valve 12 can adjust its opening degree according to the information fed back to the system by the gas return sensor 15, so as to ensure the stable liquid supply to the evaporator 13 and the zero superheated vapor state of the gas return.

[0039] A liquid level switch 19 is installed on the miniature gas-liquid separator 16. When the refrigerant level in the miniature gas-liquid separator 16 reaches the level of the liquid level switch 19, the liquid level switch 19 will send a feedback signal to the liquid supply solenoid valve 11 and close the liquid supply solenoid valve 11. After the liquid supply solenoid valve 11 is closed, when the evaporator 13 is cooling normally, the liquid refrigerant in the miniature gas-liquid separator 16 can enter the evaporator 13 through the liquid outlet to participate in the cyclic refrigeration. When the refrigerant reaches below the safe liquid level, a feedback signal can be sent and the liquid supply solenoid valve 11 can be opened to ensure the liquid supply of the system.

[0040] Example 1

[0041] In a gravity-fed refrigeration system with a large elevation difference, the main refrigeration equipment—the refrigeration unit, the condenser-evaporator skid, and the condenser—can be installed at a higher position than the evaporator, such as on the roof of a cold storage facility. The liquid refrigerant flows to the terminal evaporator under siphon action, absorbs heat in the evaporator, and turns into a gaseous state. It then returns to the condenser-evaporator skid, where it condenses back into a liquid state, creating a reciprocating refrigeration cycle. This embodiment uses Freon and carbon dioxide as refrigerants for reference.

[0042] Specifically, it includes: 1. Freon refrigeration compressor; 2. Freon oil separator; 3. Freon condenser; 4. Freon liquid receiver; 5. Freon liquid supply electric regulating valve; 6. Freon gas-liquid separator; 7. Freon / carbon dioxide heat exchanger; 8. Carbon dioxide liquid receiver (also serving as a carbon dioxide gas-liquid separator); 9. Shut-off valve; 10. Filter; 11. Liquid supply solenoid valve; 12. Electric regulating valve; 13. Carbon dioxide evaporator; 14. Shut-off valve for sensor; 15. Sensor; 16. Miniature gas-liquid separator; 17. Shut-off valve; 18. One-way shut-off valve; 19. Liquid level switch for miniature gas-liquid separator.

[0043] The interface of the Freon refrigeration compressor 1 is divided into two paths: one is the suction end, where the suction port of the Freon refrigeration compressor 1 is connected to the outlet of the Freon gas-liquid separator 6 through a pipeline; the other is the discharge end, where the discharge port of the Freon refrigeration compressor 1 is connected to the inlet of the Freon oil separator 2 through a pipeline.

[0044] The exhaust port of the Freon oil separator 2 is connected to the inlet of the Freon condenser 3 via a pipeline.

[0045] The outlet of the Freon condenser 3 and the inlet of the Freon reservoir 4 are connected by a pipeline.

[0046] The outlet of the Freon reservoir 4 is connected to the inlet of the Freon gas-liquid separator 6 via a pipeline, and an electric regulating valve 5 for Freon supply is installed at the end of the pipeline.

[0047] The Freon / carbon dioxide heat exchanger 7 has two sets of refrigerant interfaces. One set is a Freon refrigerant interface, with the liquid inlet connected to the liquid outlet of the Freon gas-liquid separator 6 via a pipeline; the gas outlet is connected to the gas inlet of the Freon gas-liquid separator 6 via a pipeline. The other set is a carbon dioxide refrigerant interface, with the gas inlet and liquid outlet connected to the gas outlet and liquid inlet of the carbon dioxide receiver (which also serves as a carbon dioxide gas-liquid separator) 8, respectively.

[0048] The outlet of the carbon dioxide storage tank (which also serves as a carbon dioxide gas-liquid separator) 8 is connected in sequence to the shut-off valve 9, the filter 10, the liquid supply solenoid valve 11, the electric regulating valve 12, and the carbon dioxide evaporator 13 via pipelines.

[0049] The carbon dioxide evaporator 13 is connected to the miniature gas-liquid separator 16 via a pipeline, and a sensor 15 and a sensor shut-off valve 14 are installed on the connecting pipeline.

[0050] The miniature gas-liquid separator 16 is equipped with a liquid level switch 19 for the miniature gas-liquid separator.

[0051] The outlet of the miniature gas-liquid separator 16 is connected to the one-way shut-off valve 18 via a pipeline.

[0052] The one-way shut-off valve 18 is connected to the electric regulating valve 12 and the carbon dioxide evaporator 13 via a pipeline.

[0053] The outlet of the miniature gas-liquid separator 16 is connected to the inlet of the carbon dioxide reservoir (which also functions as a carbon dioxide gas-liquid separator) 8 via a pipeline through a shut-off valve 17.

[0054] The main refrigeration equipment in the computer room includes a Freon condenser 3, a Freon liquid receiver 4, a Freon refrigeration unit, and a Freon / carbon dioxide condenser-evaporator skid. The refrigeration unit includes a Freon refrigeration compressor 1 and a Freon oil separator 2. The Freon / carbon dioxide condenser-evaporator skid includes a Freon liquid supply electric regulating valve 5, a Freon gas-liquid separator 6, a Freon / carbon dioxide heat exchanger 7, and a carbon dioxide liquid receiver (which also functions as a carbon dioxide gas-liquid separator) 8. Each refrigeration unit is connected by refrigeration piping.

[0055] During operation, gaseous carbon dioxide from the cold room terminal evaporator 13 is separated by the carbon dioxide receiver (which also functions as a carbon dioxide gas-liquid separator) 8 and enters the Freon / carbon dioxide heat exchanger 7 to exchange heat with Freon. The carbon dioxide is condensed from a gaseous state into a liquid state and enters the carbon dioxide receiver (which also functions as a carbon dioxide gas-liquid separator) 8. The Freon is converted from a liquid state to a gaseous state and returns to the Freon gas-liquid separator 6. The gaseous refrigerant in the Freon gas-liquid separator 6 is drawn and compressed by the Freon compressor 1 and discharged into the Freon oil separator 2, and then enters the Freon condenser 3. In the condenser 3, the Freon is converted from a gaseous state to a liquid state and flows into the Freon receiver 4. The liquid refrigerant in the Freon receiver 4 flows through the Freon liquid supply electric regulating valve 5 according to the liquid level requirement of the Freon gas-liquid separator 6 in the condenser-evaporator skid and enters the Freon gas-liquid separator 6, and then flows into the Freon / carbon dioxide heat exchanger 7 to exchange heat with carbon dioxide.

[0056] The main refrigeration equipment in the cold room is a carbon dioxide evaporator 13 and a miniature gas-liquid separator 16. The liquid supply port of the carbon dioxide evaporator 13 is connected to the liquid outlet of the carbon dioxide receiver (which also functions as a carbon dioxide gas-liquid separator) 8 in the computer room via a refrigeration pipeline, and a shut-off valve 9, a filter 10, a liquid supply solenoid valve 11, and an electric regulating valve 12 are installed sequentially between them. The return port of the carbon dioxide evaporator 13 is connected to the miniature gas-liquid separator 16 via a pipeline, and a sensor 15 is installed between the return port of the carbon dioxide evaporator 13 and the miniature gas-liquid separator 16. The miniature gas-liquid separator 16 is connected to the inlet of the carbon dioxide receiver (which also functions as a carbon dioxide gas-liquid separator) 8 via a shut-off valve 17 and a pipeline. The outlet of the carbon dioxide receiver (which also functions as a carbon dioxide gas-liquid separator) 8 is connected to the inlet of the Freon / carbon dioxide heat exchanger 7 in the computer room via a pipeline. The outlet of the carbon dioxide heat exchanger 7 is connected to the inlet of the carbon dioxide storage tank (which also serves as a carbon dioxide gas-liquid separator) 8 via a pipeline. Liquid refrigerant from the carbon dioxide storage tank (which also serves as a carbon dioxide gas-liquid separator) 8 in the computer room enters the carbon dioxide evaporator 13 through the liquid supply pipeline. In the evaporator 13, carbon dioxide changes from liquid to gas through heat exchange with the outside environment. The gaseous carbon dioxide enters the miniature gas-liquid separator 16 through the return gas port of the evaporator 13, and then enters the carbon dioxide storage tank (which also serves as a carbon dioxide gas-liquid separator) 8 in the computer room for separation before entering the Freon / carbon dioxide heat exchanger 7 to exchange heat with Freon. During the cooling process of the carbon dioxide evaporator 13, the liquid supply electric regulating valve 12 can adjust its opening degree according to the information fed back to the system by the return gas end sensor 15 to ensure stable liquid supply to the evaporator 13 and a zero superheated vapor state in the return gas.

[0057] The outlet of the miniature gas-liquid separator 16 and the one-way shut-off valve 18 are connected in sequence to the liquid supply electric regulating valve 12 and the liquid inlet of the carbon dioxide evaporator 13 via pipelines. A liquid level switch 19 is installed on the miniature gas-liquid separator 16. When the refrigerant level in the miniature gas-liquid separator 16 reaches the level of the liquid level switch 19, the liquid level switch 19 will send a feedback signal to the liquid supply solenoid valve 11 and close the liquid supply solenoid valve 11. After the liquid supply solenoid valve 11 is closed, when the evaporator 13 is cooling normally, the liquid refrigerant in the miniature gas-liquid separator 16 can enter the evaporator 13 through the outlet to participate in the cyclic refrigeration. When the refrigerant level reaches below the safe level, a feedback signal can be sent and the liquid supply solenoid valve 11 can be opened to ensure the liquid supply of the system.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 gravity-fed refrigeration system with a large elevation difference, characterized in that, The system includes a refrigeration compressor (1), whose suction port is connected to the outlet of a gas-liquid separator (6), whose discharge port is connected to the inlet of an oil separator (2), whose discharge port is connected to the inlet of a condenser (3), whose liquid outlet is connected to the inlet of a first liquid receiver (4), whose liquid outlet is connected to the inlet of a gas-liquid separator (6), whose liquid outlet is connected to the inlet of a heat exchanger (7), and whose first refrigerant outlet is connected to the gas-liquid separator (6). The inlet of the heat exchanger (7) is connected to the inlet of the second refrigerant, and the outlet of the second refrigerant is connected to the outlet of the second liquid receiver (8) and the outlet of the second liquid receiver (8) is connected to the liquid supply port of the evaporator (13) through the first pipe. The return port of the evaporator (13) is connected to the micro gas-liquid separator (16) through the second pipe. The outlet of the micro gas-liquid separator (16) is connected to the inlet of the second liquid receiver (8) through the third pipe. The outlet of the micro gas-liquid separator (16) is connected to one end of the one-way shut-off valve (18), and the other end of the one-way shut-off valve (18) is connected to the first pipe.

2. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 1, characterized in that, The first pipeline is sequentially equipped with a first shut-off valve (9), a filter (10), a liquid supply solenoid valve (11), and an electric regulating valve (12).

3. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 2, characterized in that, A sensor (15) is installed on the second pipeline, and a sensor shut-off valve (14) is connected below the sensor (15).

4. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 3, characterized in that, The outlet of the first liquid reservoir (4) is connected to the inlet of the gas-liquid separator (6) through a pipe, and the end of the pipe is provided with a liquid supply electric regulating valve (5).

5. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 1, characterized in that, A liquid level switch (19) is installed on the micro gas-liquid separator (16).

6. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 2, characterized in that, The one-way shut-off valve (18) is connected to the first pipe between the electric regulating valve (12) and the evaporator (13).

7. The gravity-fed liquid supply refrigeration system with large elevation difference according to claim 1, characterized in that, A second shut-off valve (17) is installed on the third pipeline.

8. A method for operating a gravity-fed refrigeration system with a large elevation difference, implemented based on the gravity-fed refrigeration system with a large elevation difference as described in claim 4, characterized in that... Includes the following steps: During operation, the gaseous second refrigerant from the terminal evaporator (13) in the cold room is separated by the second liquid receiver (8) and enters the heat exchanger (7) to exchange heat with the liquid first refrigerant. The second refrigerant is condensed from gaseous to liquid and enters the second liquid receiver (8). The first refrigerant is converted from liquid to gas and returns to the gas-liquid separator (6). The first refrigerant in the gas-liquid separator (6) is drawn and compressed by the refrigeration compressor (1) and discharged into the oil separator (2), and then enters the condenser (3). The first refrigerant is converted from gaseous to liquid in the condenser (3) and flows into the first liquid receiver (4). The first refrigerant in the first liquid receiver (4) flows through the liquid supply electric regulating valve (5) into the gas-liquid separator (6) according to the liquid level requirements of the gas-liquid separator (6) in the condenser-evaporator skid and then flows into the heat exchanger (7) to exchange heat with the second refrigerant. The second refrigerant from the second liquid receiver (8) in the computer room enters the evaporator (13) through the liquid supply pipeline; in the evaporator (13), the second refrigerant changes from liquid to gas through heat exchange with the outside; the gaseous second refrigerant enters the micro gas-liquid separator (16) through the return gas port of the evaporator (13), and then enters the second liquid receiver (8) in the computer room for separation before entering the heat exchanger (7) to exchange heat with the first refrigerant; during the cooling process of the evaporator (13), the electric regulating valve (12) can adjust its opening degree according to the information fed back to the system by the return gas end sensor (15) to ensure stable liquid supply to the evaporator (13) and zero superheated vapor state of the return gas.

9. The working method of the gravity-fed liquid supply refrigeration system with large elevation difference according to claim 8, characterized in that, A liquid level switch (19) is installed on the micro gas-liquid separator (16). When the refrigerant level in the micro gas-liquid separator (16) reaches the level of the liquid level switch (19), the liquid level switch (19) will send a feedback signal to the liquid supply solenoid valve (11) and close the liquid supply solenoid valve (11). After the liquid supply solenoid valve (11) is closed, when the evaporator (13) is cooling normally, the liquid refrigerant in the micro gas-liquid separator (16) can enter the evaporator (13) through the liquid outlet to participate in the cyclic refrigeration. When the refrigerant reaches below the safe liquid level, a feedback signal can be sent and the liquid supply solenoid valve (11) can be opened to ensure the liquid supply of the system.

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