Refrigerating system, air supply method of refrigerating system and stop control method of refrigerating system

Abstract

The invention provides a refrigerating system, an air supply method of the refrigerating system and a stop control method.The refrigerating system comprises a compressor, an oil separator, a condenser, a liquid storage device, an economizer, a main path liquid collector and an evaporator, the compressor is provided with a first-stage air suction port, a middle air supply port and an exhaust port, and a liquid supply pipeline is formed from the main path liquid collector to the evaporator; an air suction pipeline is led out from the evaporator to a first-stage air suction port of the compressor, and an intercooling pipeline is led out from the economizer to a middle air supply port of the compressor; a first detection unit used for detecting the liquid supply amount in the main path liquid collector is arranged at the main path liquid collector, a flash gas bypass pipeline is arranged between the main path liquid collector and the compressor, and a flash gas bypass electromagnetic valve and a flash gas bypass expansion valve are arranged on the flash gas bypass pipeline; when the liquid storage amount of the main path liquid collector is lower than a set value, the flash gas bypass electromagnetic valve is opened, and the flash gas bypass expansion valve starts to work; and when the liquid storage amount in the main path liquid collector reaches a set value, the flash gas bypass electromagnetic valve is closed, and the flash gas bypass expansion valve stops working.

Description

Technical Field

[0001] This invention relates to the field of refrigeration system technology, specifically to a refrigeration system, a method for replenishing gas in the refrigeration system, and a method for controlling its shutdown. Background Technology

[0002] In refrigeration systems, due to installation site limitations, the quick-freezing equipment may be located higher than the refrigeration unit skid (typically consisting of a compressor, oil separator, condenser, receiver, economizer, liquid collector, and connecting pipes), and the refrigeration piping may be quite long. After shutdown, liquid refrigerant will fall back into the receiver on the refrigeration unit skid due to gravity. When the equipment is restarted, due to the height difference between the refrigeration unit skid and the evaporator, and the long refrigeration piping, the refrigerant cannot quickly enter the evaporator, resulting in excessively low suction pressure. This triggers an alarm and shutdown of the refrigeration unit, and the evaporator cannot operate normally to cool down. Prolonged operation of the compressor under low suction pressure can easily cause a sudden rise in exhaust temperature, decreased energy efficiency, and in severe cases, carbonization and coking of the lubricating oil, wear of the compressor bearings, and compressor damage.

[0003] To quickly increase suction pressure, a gas line is typically drawn from the exhaust pipe, depressurized by an expansion valve, and then connected to the compressor's suction pipe, allowing for rapid replenishment of suction pressure. However, the high-temperature, high-pressure gas in the exhaust pipe, after being depressurized and then compressed by the compressor, can easily cause adverse phenomena such as excessively high exhaust temperature and compressor overheating. This is especially true for single-unit two-stage compressors, where excessively high exhaust temperatures after compression by two stages can affect the stability of the entire refrigeration system.

[0004] Furthermore, in direct expansion refrigeration systems, the refrigerant liquid is prone to generating a large amount of flash gas after being throttled and depressurized by the expansion valve. These flash gases entering the evaporator reduce the heat exchange efficiency of the refrigerant liquid; due to the long, complex, and winding liquid supply pipeline with height differences, the backflow process easily forms new flash gases, leading to a decrease in system cooling capacity and an increase in energy consumption.

[0005] Therefore, in refrigeration systems where the quick-freezing equipment is located higher than the refrigeration unit skid due to installation site limitations, it is necessary to design a refrigeration system that can quickly replenish the pressure when the equipment is started. Summary of the Invention

[0006] The purpose of this invention is to provide a refrigeration system, a method for replenishing gas in the refrigeration system, and a method for controlling its shutdown, in order to solve the above-mentioned problems.

[0007] The technical solution adopted in this invention is as follows:

[0008] A refrigeration system includes a compressor, an oil separator, a condenser, a liquid receiver, an economizer, a main liquid collector, and an evaporator connected in sequence. The compressor has a primary suction port, an intermediate gas supply port, and a discharge port. A liquid supply pipeline is formed from the main liquid collector to the evaporator. A suction pipeline is led out from the evaporator and connected to the primary suction port of the compressor. An intercooling pipeline is led out from the economizer and connected to the intermediate gas supply port of the compressor. A first detection unit for detecting the liquid supply in the main liquid collector is provided at the main liquid collector. A flash bypass pipeline is provided between the main liquid collector and the first-stage suction port of the compressor. A flash bypass solenoid valve and a flash bypass expansion valve are provided on the flash bypass pipeline. When the first detection unit detects that the liquid level in the main liquid collector is lower than a set value, it controls the flash bypass solenoid valve to open and the flash bypass expansion valve to start working. When the first detection unit detects that the liquid level in the main liquid collector reaches the set value, it controls the flash bypass solenoid valve to close and the flash bypass expansion valve to stop working.

[0009] As a further improvement of the present invention, an intercooling bypass pipeline is provided between the intercooling gas outlet of the economizer and the first-stage suction port of the compressor, and an intercooling bypass solenoid valve is provided on the intercooling bypass pipeline.

[0010] As a further improved technical solution of the present invention, an intermediate liquid storage unit is provided between the main liquid collector and the evaporator. The intermediate liquid storage unit includes a high-level liquid collector and a second detection unit for detecting the liquid supply of the high-level liquid collector. The high-level liquid collector is located close to the evaporator. A first main line shut-off solenoid valve is provided between the high-level liquid collector and the main liquid collector, and a second main line shut-off solenoid valve is provided between the high-level liquid collector and the evaporator.

[0011] As a further improvement of the present invention, a main solenoid valve and a main expansion valve are provided between the main liquid collector and the evaporator, and the intermediate liquid storage unit is provided between the main solenoid valve and the main expansion valve.

[0012] As a further improvement of the present invention, a pressure detection unit is provided on the suction pipe connecting the evaporator and the compressor. The pressure detection unit is used to detect the pressure at the first-stage suction port of the compressor.

[0013] As a further improved technical solution of the present invention, the second detection unit is used to detect the high liquid level supply of the high liquid level collector, and a third detection unit is also provided at the high liquid level collector, the third detection unit being used to detect the low liquid level supply of the high liquid level collector.

[0014] A method for replenishing gas in a refrigeration system, based on the refrigeration system described above, comprises the following steps: S1. Open the intercooler bypass solenoid valve to supply the refrigerant gas from the economizer into the first-stage suction port of the compressor; S2. When the first detection unit detects that the refrigerant supply in the main liquid collector is lower than the set supply value, the flash gas bypass solenoid valve is opened to throttle and reduce the pressure of the flash gas in the liquid supply line and supplement it to the first-stage suction port of the compressor. S3. When the first detection unit detects that the refrigerant supply in the main liquid collector has reached the set supply value, the flash bypass solenoid valve and the intercooler bypass solenoid valve are closed.

[0015] As a further improvement to the present invention, there is a step S0 before step S1, and step S0 is as follows: When the refrigeration system is started, the first main circuit shut-off solenoid valve and the second main circuit shut-off solenoid valve are opened, and the refrigerant in the high-level liquid collector flows into the liquid supply pipeline and the evaporator. When the compressor start-up conditions are met, the compressor is started.

[0016] As a further improved technical solution of the present invention, the starting conditions of the compressor in step S0 are: the third detection unit detects that the liquid level in the high-level liquid collector reaches the low liquid level, or the pressure detection unit detects that the pressure at the first-stage suction port of the compressor reaches the starting set value.

[0017] A method for stopping a refrigeration system, based on the refrigeration system described above, is as follows: When the refrigeration system stops, the second main circuit shut-off solenoid valve is closed. When the second detection unit detects that the refrigerant in the high-level liquid collector has reached the set liquid supply amount, the first main circuit shut-off solenoid valve is closed, and the compressor is shut down.

[0018] The beneficial effects of this invention are as follows: With the above structure, the flash gas bypass pipeline not only replenishes the compressor with gas but also solves the problem of flash gas stagnation in the pipeline, improving the working efficiency of the evaporator and avoiding shutdown failures triggered by low pressure. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a refrigeration system with only a flash bypass line; Figure 2 This is a schematic diagram of a refrigeration system with flash bypass piping and intercooler bypass piping; Figure 3 This is a schematic diagram of a refrigeration system with an intermediate liquid storage unit.

[0020] Wherein: 1-Compressor, 2-Oil separator, 3-Condenser, 4-Liquid receiver, 5-Economizer, 6-Economizer expansion valve, 7-Main circuit liquid collector, 8-First detection unit, 9-Main circuit solenoid valve, 10-Main circuit expansion valve, 11-Evaporator, 12-Flash bypass solenoid valve, 13-Flash bypass expansion valve, 14-Intercooler bypass solenoid valve, 15-First main circuit shut-off solenoid valve, 16-High-level liquid collector, 17-Second detection unit, 18-Second main circuit shut-off solenoid valve, 19-Third detection unit, 20-Pressure detection unit; 101-Liquid supply line, 102-Suction line, 103-Intercooler line, 104-Heat exchange branch, 105-Flash bypass line, 106-Intercooler bypass line. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0022] If the description of this invention involves orientation (e.g., up, down, left, right, front, back, outside, inside, etc.), then the orientations involved need to be defined. For example, "To clearly express the positions and directions described in this invention, the operator of the device is used as a reference, the end closer to the operator is the proximal end, and the end farther from the operator is the distal end." Or, the paper can be used as a reference. Of course, if the positional relationship between the two is defined by mutual reference in the subsequent description, then this definition is not necessary.

[0023] A refrigeration system, such as Figure 1 As shown, the refrigeration system includes a compressor 1, an oil separator 2, a condenser 3, a liquid receiver 4, an economizer 5, a main liquid collector 7, and an evaporator 11 connected in sequence. The compressor 1 is a single-unit two-stage compressor with a primary suction port, an intermediate gas injection port, and a discharge port. A liquid supply pipeline 101 is formed from the economizer 5 and the main liquid collector 7 to the evaporator 11 for transporting refrigerant. A suction pipeline 102 is led out from the evaporator 11 and connected to the primary suction port of the compressor 1 to provide low-pressure refrigerant gas to the compressor 1. An intercooling pipeline 103 is led out from the economizer 5 and connected to the intermediate gas injection port of the compressor 1 to reduce the discharge temperature of the compressor 1. A main solenoid valve 9 and a main expansion valve 10 are also sequentially arranged between the main liquid collector 7 and the evaporator 11. In terms of physical space during installation, the evaporator 11 is higher than the compressor 1. The high-pressure refrigerant liquid flowing out from the economizer 5 is transported through the liquid supply line 101 and flows sequentially through the main line liquid collector 7, the main line solenoid valve 9, and the main line expansion valve 10. The main line solenoid valve 9 opens and closes in coordination with the start and stop of the compressor 1 to prevent liquid refrigerant from continuing to flow into the evaporator 11 and causing liquid slugging when the compressor is stopped. The main line expansion valve 10 throttles and reduces the pressure of the high-pressure refrigerant liquid into a low-pressure gas-liquid two-phase mixture, which is supplied to the evaporator 11 for heat absorption and evaporation. The resulting low-pressure refrigerant gas returns to the first-stage suction port of the compressor 1 through the suction line 102, completing one system operation cycle. A first detection unit 8 is provided at the main liquid collector 7 to detect the liquid supply in the main liquid collector 7. The first detection unit 8 is used to detect whether the liquid supply in the main liquid collector 7 is sufficient. A flash bypass pipeline 105 is provided between the high-pressure side of the main liquid collector 7 and the first-stage suction port of the compressor 1. A flash bypass solenoid valve 12 and a flash bypass expansion valve 13 are provided on the flash bypass pipeline 105. Specifically, the flash bypass pipeline 105 is led out between the main liquid collector 7 and the first-stage suction port of the compressor 1. The flash bypass solenoid valve 12 is used to realize the rapid opening and closing of the flash bypass pipeline 105, and the flash bypass expansion valve 13 is used to smoothly reduce the pressure of the refrigerant supplied by the main liquid collector 7 to the suction pressure level of the compressor 1.

[0024] When the system is running, when the first detection unit 8 detects that the liquid storage in the main liquid collector 7 has reached the set value, it controls the flash bypass solenoid valve 12 to remain closed, the flash bypass expansion valve 13 to stop working, and the refrigerant flows along the preset liquid supply pipeline 101. When the first detection unit 8 detects that the liquid level in the main liquid collector 7 is lower than the set value, it controls the flash gas bypass solenoid valve 12 to open and the flash gas bypass expansion valve 13 to start working. At this time, the flash gas that is stuck in the liquid supply line 101 is introduced into the flash gas bypass line 105. After being throttled and depressurized by the flash gas bypass expansion valve 13, it is converted into low-pressure refrigerant gas and replenished to the suction line 102, thereby quickly increasing the suction pressure of the compressor 1 and avoiding shutdown faults triggered by low pressure. In addition, it also actively discharges the flash gas that affects heat exchange from the liquid supply line 101, reducing the instability of the gas-liquid two-phase flow in the evaporator 11 and further improving the working efficiency of the evaporator 11.

[0025] In this embodiment, the first detection unit 8 can be a photoelectric level switch, a float switch, or the like. This invention uses a photoelectric level switch, which is a non-contact detection switch. This avoids the risks of jamming and wear associated with conventional mechanical structures. Furthermore, its sealed structure can adapt to the low-temperature, high-pressure environment of a refrigeration system, ensuring stable detection and good reliability.

[0026] In this embodiment, a heat exchange branch 104 is provided between the economizer 5 and the main liquid collector 7, and an economizer expansion valve 6 is installed on the heat exchange branch 104. The heat exchange branch 104 returns to the economizer 5. The high-pressure refrigerant liquid flowing out of the economizer 5 is throttled and depressurized by the economizer expansion valve 6, becoming a low-pressure gas-liquid mixture, and then returns to the interior of the economizer 5. Inside the economizer 5, it evaporates, absorbing the heat of the refrigerant liquid that is about to enter the liquid supply line 101, further reducing its temperature. The low-pressure refrigerant gas generated by evaporation is led to the intermediate gas inlet of the compressor 1 through the intercooler line 103, replenishing the gas and reducing the gas temperature of the compressor 1, thereby improving the working efficiency of the refrigeration system.

[0027] As one embodiment of the present invention, such as Figure 2 As shown, to achieve rapid gas replenishment, in addition to the aforementioned flash bypass line 105, an intercooler bypass line 106 is installed between the intercooler gas outlet of the economizer 5 and the first-stage suction port of the compressor 1. An intercooler bypass solenoid valve 14 is installed on the intercooler bypass line 106. Since the refrigerant gas inside the economizer 5 has been pre-cooled, its temperature is lower than the first-stage discharge temperature of the compressor 1. When the suction pressure of the compressor 1 is low or an alarm prevention is required, the controller controls the intercooler bypass solenoid valve 14 to open, directly replenishing the low-temperature refrigerant gas in the intercooler line 103 into the first-stage suction port of the compressor 1, where it mixes with the refrigerant gas from the evaporator 11. The intercooler bypass line 106 provides a stable supply of refrigerant gas quickly, preventing alarms caused by low suction pressure of the compressor 1. Compared to the aforementioned flash bypass line 105, the intercooler bypass line 106 is the main gas supply line in the gas supply structure, while the flash bypass line 105 is the auxiliary gas supply line, forming a dual-complementary gas supply system. The intercooler bypass line 106, as the main gas supply line, provides regular and stable low-temperature gas supply to optimize energy efficiency and temperature. The flash bypass line 105, as the auxiliary gas supply line, rapidly injects gas to cope with a sudden pressure drop when an abnormality is detected on the liquid supply side. Together, they can quickly replenish the suction pressure, ensuring smooth start-up and stable operation of the compressor 1.

[0028] Typically, when there is a height difference between the evaporator 11 and the compressor 1, but the pipeline is not very long, only the flash bypass pipeline 105 can be used for gas replenishment; when there is a height difference between the evaporator 11 and the compressor 1, and the pipeline is very long, a large amount of refrigerant gas is required, and both the intercooler bypass pipeline 106 and the flash bypass pipeline 105 can be used for gas replenishment at the same time.

[0029] The present invention also provides an embodiment for harsh environments, such as when the height difference is very large and the pipe length is very long, for example... Figure 3 As shown, an intermediate liquid storage unit is also provided on the liquid supply line 101. The intermediate liquid storage unit includes a high-level liquid collector 16 and a second detection unit 17 for detecting the liquid supply of the high-level liquid collector 16. The high-level liquid collector 16 is located between the main liquid collector 7 and the evaporator 11, and is actually located between the main solenoid valve 9 and the main expansion valve 10. The high-level liquid collector 16 and the main expansion valve 10 are located close to the evaporator 11. In terms of physical space during installation, the outlet of the high-level liquid collector 16 is higher than the refrigerant inlet of the evaporator 11. A first main-line shut-off solenoid valve 15 is provided between the high-level liquid collector 16 and the main liquid collector 7, and a second main-line shut-off solenoid valve 18 is provided between the high-level liquid collector 16 and the evaporator 11. The intermediate liquid storage unit is used for liquid storage or liquid supply, realizing liquid storage when the system is shut down and liquid supply when the system is started, so as to meet the rapid start-up of the compressor 1.

[0030] Specifically, when the system is shut down, the second main circuit cut-off solenoid valve 18 is first closed, preventing the refrigerant on the liquid supply line 101 from flowing to the evaporator 11 or the suction line 102. Meanwhile, the refrigerant supplied from the liquid receiver 4, the economizer 5, and the main circuit liquid collector 7 can be continuously injected into the high-level liquid collector 16. When the second detection unit 17 detects that the refrigerant level in the high-level liquid collector 16 has reached the set level, i.e., the refrigerant charge meets the requirements for the safe start-up of the compressor 1, the first main circuit cut-off solenoid valve 15 is then closed to cut off the upstream liquid supply. This allows the pipeline between the first main circuit cut-off solenoid valve 15 and the second main circuit cut-off solenoid valve 18, as well as the high-level liquid collector 16, to form an independent intermediate liquid storage unit. The compressor 1 is then shut down, and the refrigerant in the remaining liquid supply lines 101 flows back to the liquid receiver 4. When the system is started, the first main circuit shut-off solenoid valve 15 and the second main circuit shut-off solenoid valve 18 are opened first. Since the high-level liquid collector 16 is higher than the evaporator 11, and the evaporator 11 is higher than the liquid receiver 4, under the action of gravity, the refrigerant in the high-level liquid collector 16 can be quickly replenished to the liquid supply line 101 and the evaporator 11. The refrigerant reaches the first-stage suction port of the compressor 1 through the main circuit expansion valve 10 and the evaporator 11. At this time, the main circuit solenoid valve 9 is in the closed state. When the starting conditions of the compressor 1 are met, the compressor 1 is started, the main circuit solenoid valve 9 is opened, and the system is running.

[0031] The configuration of this intermediate liquid storage unit ensures that there is sufficient and subcooled liquid refrigerant on the evaporator 11 side before each start-up, completely avoiding start-up failure rates caused by refrigerant migration or insufficiency.

[0032] Furthermore, to ensure the safe start-up and operation of the compressor 1, this invention provides an embodiment of the start-up conditions for the compressor 1. A third detection unit 19 is also provided at the high-level liquid collector 16. The second detection unit 17 is used to detect the high-level liquid supply of the high-level liquid collector 16, and the third detection unit 19 is used to detect the low-level liquid supply of the high-level liquid collector 16. When the second detection unit 17 detects that the liquid level in the high-level liquid collector 16 has reached the high level, it indicates that the refrigerant liquid level in the high-level liquid collector 16 meets the refrigerant quantity required for the compressor 1 to start. At this time, the first main circuit shut-off solenoid valve 15 can be closed to shut down the compressor 1. When the system starts, when the third detection unit 19 detects that the liquid level in the high-level liquid collector 16 is at the low level, it indicates that the high-level liquid collector 16 has replenished the refrigerant supply required in the liquid supply pipeline 101 and the front end pipeline of the main circuit expansion valve 10. At this time, the compressor 1 can be started to begin system operation. Specifically, both the second detection unit 17 and the third detection unit 19 can be photoelectric liquid level switches.

[0033] This invention also provides another embodiment of the starting conditions for compressor 1. A pressure detection unit 20 is provided on the suction line 102 connecting the evaporator 11 and compressor 1. The pressure detection unit 20 is located near the first-stage suction port of compressor 1. The pressure detection unit 20 is used to detect the pressure at the first-stage suction port of compressor 1. By monitoring the pressure at the first-stage suction port of compressor 1 in real time, when the detected pressure value is lower than the system's preset safety threshold, it indicates that there is insufficient refrigerant in the system, and compressor 1 cannot start normally. The pressure detection unit 20 will output an alarm signal, and the controller will control the flash bypass solenoid valve 12 to open, replenishing refrigerant to suction line 102. When the detected pressure reaches the system's preset safety threshold for a period of time, the pressure detection unit 20 will not output an alarm signal. At this time, the controller can control the flash bypass solenoid valve 12 to close, and compressor 1 can be started. Specifically, the pressure detection unit 20 can be a piezoresistive or piezoelectric sensor probe.

[0034] The detection by the third detection unit 19 or the pressure detection unit 20 can effectively prevent the compressor 1 from operating abnormally, avoid low suction pressure or motor overload, and greatly improve the start-up reliability and the life of the compressor 1.

[0035] The present invention also provides a method for replenishing gas in a refrigeration system, based on the refrigeration system described above, comprising the following steps: S1. Open the intercooler bypass solenoid valve 14 to supply the refrigerant gas from the economizer 5 into the first-stage suction port of the compressor 1; S2. When the first detection unit 8 detects that the refrigerant supply in the main liquid collector 7 is lower than the set supply value, the flash gas bypass solenoid valve 12 is opened and the flash gas bypass expansion valve 13 starts to work, throttling and reducing the pressure of the flash gas in the liquid supply pipeline 101 to supplement the first-stage suction port of the compressor 1. S3. When the first detection unit 8 detects that the refrigerant supply in the main liquid collector 7 has reached the set supply value, the flash bypass solenoid valve 12 and the intercooler bypass solenoid valve 14 are closed, and the flash bypass expansion valve 13 stops working.

[0036] Furthermore, before step S1, there is step S0, which is as follows: When the refrigeration system is started, the first main circuit shut-off solenoid valve 15 and the second main circuit shut-off solenoid valve 18 are opened, and the refrigerant in the high-level liquid collector 16 flows into the liquid supply pipeline 101 and the evaporator 11. When the starting conditions of the compressor 1 are met, the compressor 1 is started.

[0037] Specifically, the starting conditions for compressor 1 in step S0 are: the third detection unit 19 detects that the liquid level in the high-level liquid collector 16 has reached a low level, or the pressure detection unit 20 detects that the pressure at the first-stage suction port of compressor 1 has reached the starting set value.

[0038] This collaborative approach, involving the intercooler bypass line 106, the flash gas bypass line 105, and the intermediate liquid storage unit, is applicable to harsh working environments. The intermediate liquid storage unit fundamentally avoids the liquid supply gap during startup, ensuring the compressor 1 can start normally and establish a pressure differential. Subsequently, the intercooler bypass line 106, either independently or in conjunction with the flash gas bypass line 105, increases the gas supply speed within the system during the initial operation phase, enabling rapid gas supply, ensuring pressure stability, and facilitating a faster transition to the normal gas supply cycle. The integrated use of these three components ensures that the refrigeration system can achieve safe, rapid, and efficient startup under any circumstances.

[0039] The present invention also provides a method for stopping a refrigeration system, based on the refrigeration system described above, and the method is as follows: When the refrigeration system stops, the second main circuit shut-off solenoid valve 18 is closed. When the second detection unit 17 detects that the refrigerant in the high-level liquid collector 16 has reached the set liquid supply amount, the first main circuit shut-off solenoid valve 15 is closed, and the compressor 1 is shut down.

[0040] In this embodiment, the set liquid supply amount is at least the amount of refrigerant required for one evaporation of the evaporator 11, so that the stored refrigerant can meet the minimum guarantee for rapid start-up, while avoiding excessive storage of refrigerant in the high-level liquid collector 16.

[0041] The refrigeration system, gas replenishment method, and shutdown control method provided by this invention include a flash gas bypass pipeline 105, which not only replenishes gas to the compressor 1 but also solves the problem of flash gas stagnation in the pipeline, thus improving the working efficiency of the evaporator 11; an intercooler bypass pipeline 106, which not only replenishes gas to the compressor 1 but also has a cooling function to prevent the compressor 1 from overheating; the two gas replenishment pipelines can be used independently or work together, improving the gas replenishment efficiency; and the intermediate liquid storage unit improves the start-up efficiency of the compressor 1. All three work together, with the intermediate liquid storage unit supplying liquid first to establish a pressure differential, and the two gas replenishment pipelines subsequently ensuring pressure stability, enabling the refrigeration system to achieve safe, fast, and efficient start-up under any circumstances.

[0042] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0043] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A refrigeration system, characterized in that: The system includes a compressor (1), an oil separator (2), a condenser (3), a liquid receiver (4), an economizer (5), a main liquid collector (7), and an evaporator (11) connected in sequence. The compressor (1) has a primary suction port, an intermediate gas supply port, and a discharge port. A liquid supply pipeline (101) is formed from the main liquid collector (7) to the evaporator (11). A suction pipeline (102) is led out from the evaporator (11) and connected to the primary suction port of the compressor (1). An intercooling pipeline (103) is led out from the economizer (5) and connected to the intermediate gas supply port of the compressor (1). A first detection unit (8) for detecting the liquid supply in the main liquid collector (7) is provided at the main liquid collector (7). A flash bypass pipeline (105) is provided between the main liquid collector (7) and the first-stage suction port of the compressor (1). A flash bypass solenoid valve (12) and a flash bypass expansion valve (13) are provided on the flash bypass pipeline (105). When the first detection unit (8) detects that the liquid storage in the main liquid collector (7) is lower than the set value, it controls the flash bypass solenoid valve (12) to open and the flash bypass expansion valve (13) to start working. When the first detection unit (8) detects that the liquid storage in the main liquid collector (7) reaches the set value, it controls the flash bypass solenoid valve (12) to close and the flash bypass expansion valve (13) to stop working.

2. The refrigeration system according to claim 1, characterized in that: A cooling bypass pipeline (106) is provided between the cooling gas outlet of the economizer (5) and the first-stage suction port of the compressor (1), and a cooling bypass solenoid valve (14) is provided on the cooling bypass pipeline (106).

3. The refrigeration system according to claim 2, characterized in that: An intermediate liquid storage unit is provided between the main liquid collector (7) and the evaporator (11). The intermediate liquid storage unit includes a high-level liquid collector (16) and a second detection unit (17) for detecting the liquid supply of the high-level liquid collector (16). The high-level liquid collector (16) is located close to the evaporator (11). A first main line shut-off solenoid valve (15) is provided between the high-level liquid collector (16) and the main liquid collector (7). A second main line shut-off solenoid valve (18) is provided between the high-level liquid collector (16) and the evaporator (11).

4. The refrigeration system according to claim 3, characterized in that: A main line solenoid valve (9) and a main line expansion valve (10) are provided between the main line liquid collector (7) and the evaporator (11), and the intermediate liquid storage unit is provided between the main line solenoid valve (9) and the main line expansion valve (10).

5. The refrigeration system according to claim 4, characterized in that: A pressure detection unit (20) is provided on the suction line (102) connecting the evaporator (11) and the compressor (1). The pressure detection unit (20) is used to detect the pressure at the first-stage suction port of the compressor (1).

6. The refrigeration system according to claim 4, characterized in that: A third detection unit (19) is also provided at the high-level liquid collector (16). The second detection unit (17) is used to detect the high-level liquid supply of the high-level liquid collector (16), and the third detection unit (19) is used to detect the low-level liquid supply of the high-level liquid collector (16).

7. A method for replenishing gas in a refrigeration system, characterized in that, Based on the refrigeration system as described in any one of claims 4 to 6, the steps are as follows: S1. Open the intercooler bypass solenoid valve (14) to supply the refrigerant gas from the economizer (5) into the first-stage suction port of the compressor (1); S2. When the first detection unit (8) detects that the refrigerant supply in the main liquid collector (7) is lower than the set supply value, the flash gas bypass solenoid valve (12) is opened to throttle and reduce the pressure of the flash gas in the liquid supply pipeline (101) and supplement it to the first-stage suction port of the compressor (1); S3. When the first detection unit (8) detects that the refrigerant supply in the main liquid collector (7) reaches the set supply value, the flash bypass solenoid valve (12) and the intercooler bypass solenoid valve (14) are closed.

8. The gas replenishment method for the refrigeration system according to claim 7, characterized in that, Before step S1, there is step S0, which is: When the refrigeration system is started, the first main circuit cut-off solenoid valve (15) and the second main circuit cut-off solenoid valve (18) are opened, and the refrigerant in the high-level liquid collector (16) flows into the liquid supply pipeline (101) and the evaporator (11). When the starting conditions of the compressor (1) are met, the compressor (1) is started.

9. The gas replenishment method for the refrigeration system according to claim 8, characterized in that, The starting conditions for the compressor (1) in step S0 are: the third detection unit (19) detects that the liquid level in the high-level liquid collector (16) has reached a low level, or the pressure detection unit (20) detects that the pressure at the first-stage suction port of the compressor (1) has reached the starting set value.

10. A method for stopping a refrigeration system, characterized in that, Based on the refrigeration system as described in claim 4, the method is as follows: When the refrigeration system stops, the second main circuit cut-off solenoid valve (18) is closed. When the second detection unit (17) detects that the refrigerant in the high-level liquid collector (16) has reached the set liquid supply amount, the first main circuit cut-off solenoid valve (15) is closed, and the compressor (1) is turned off.

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