Single-machine two-stage compression refrigeration system with external circulation

Abstract

The embodiment of the utility model discloses a single-machine two-stage compression refrigerating system with external circulation, which is characterized in that a high-pressure liquid storage device for storing a high-pressure liquid refrigerant and a hot air bypass pipeline for communicating the high-pressure liquid storage device with a first-stage air suction port of a single-machine two-stage compressor are arranged between a condenser and an intercooler; high-pressure saturated refrigerant steam in the high-pressure liquid storage device can be bypassed to the first-stage air suction port of the single-machine double-stage compressor through the hot air bypass pipeline to serve as supplement of refrigerant steam from the evaporator, it is guaranteed that the air suction pressure of the first-stage air suction port is not lower than a set threshold value, frequent starting and stopping of the compressor caused by too low air suction pressure are effectively avoided, and the service life of the compressor is prolonged. The service life of the compressor can be prolonged, system performance is improved, and system energy consumption is reduced. Besides, the hot gas bypass adjusting valve is adopted to adjust the hot gas bypass amount, and then the pressure of the mixed steam input into the first-stage air suction port is adjusted, so that the flexibility and adaptability of pressure adjustment are higher, and stable operation of the compressor within a larger load range is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of refrigeration, in particular to a single-machine two-stage compression refrigeration system with external circulation. Background Art

[0002] The single-machine two-stage compression refrigeration system is a system that includes a single-machine two-stage compressor, an evaporator, a condenser, a throttling device, and an intercooler. When the refrigeration load decreases, the suction pressure of the compressor decreases. If the refrigeration load drops to a certain level, the suction pressure of the compressor will drop below the low-pressure control value, causing the compressor to shut down. When the refrigeration load demand increases, the compressor will start again, causing the compressor to start and stop frequently. Frequent start and stop of the compressor will increase the energy consumption of the system and also have a great impact on the life of the compressor. Utility Model Content

[0003] The utility model aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the utility model proposes a single-machine two-stage compression refrigeration system with external circulation, which effectively avoids frequent start and stop of the compressor.

[0004] The single-machine two-stage compression refrigeration system with external circulation of the utility model embodiment comprises: a single-machine two-stage compressor, a condenser, a high-pressure liquid storage, an intercooler, an evaporator, a hot gas bypass pipeline and a hot gas bypass regulating valve, wherein the single-machine two-stage compressor has a primary air intake port, a secondary air intake port and a high-pressure exhaust port, wherein the high-pressure exhaust port is connected to the inlet of the condenser, and the outlet of the condenser is connected to the inlet of the high-pressure liquid storage, and the high-pressure liquid storage has a liquid outlet and a steam outlet, wherein the intercooler has a first heat exchange flow channel and a second heat exchange flow channel, and the high-pressure liquid storage has a first heat exchange flow channel and a second heat exchange flow channel. The liquid outlet of the accumulator is connected to the inlet of the first heat exchange channel and the inlet of the second heat exchange channel respectively through a first pipeline and a second pipeline connected in parallel, a first throttling device is provided on the first pipeline, the outlet of the first heat exchange channel is connected to the secondary air intake port, the outlet of the second heat exchange channel is connected to the inlet of the evaporator through the second throttling device, the outlet of the evaporator is connected to the primary air intake port, the hot gas bypass pipeline connects the steam outlet of the high-pressure liquid storage device and the primary air intake port, and the hot gas bypass regulating valve is provided on the hot gas bypass pipeline.

[0005] In some embodiments, the single-machine two-stage compression refrigeration system includes a heat recovery exchanger, the hot side of the heat recovery exchanger is connected between the high-pressure liquid storage tank and the intercooler, and the cold side of the heat recovery exchanger is connected between the evaporator and the first-stage air intake.

[0006] In some embodiments, the recuperator is a plate heat exchanger.

[0007] In some embodiments, the single-machine two-stage compression refrigeration system includes a gas-liquid separator, and the gas-liquid separator is connected between the evaporator and the primary air intake.

[0008] In some embodiments, the single-unit two-stage compression refrigeration system includes a gas-liquid separator, which is connected between the evaporator and the cold side inlet of the heat recovery exchanger.

[0009] In some embodiments, the single-unit two-stage compression refrigeration system further includes an oil separator, which is disposed between the high-pressure exhaust port of the single-unit two-stage compressor and the condenser.

[0010] In some embodiments, the single-unit two-stage compression refrigeration system also includes a first pressure sensor, which is used to monitor the suction pressure of the first-stage suction port of the single-unit two-stage compressor. The first pressure sensor is connected to the hot gas bypass regulating valve signal so as to adjust the opening of the hot gas bypass regulating valve according to the pressure monitoring value of the first pressure sensor.

[0011] In some embodiments, the single-machine two-stage compression refrigeration system further includes a second pressure sensor, which is disposed on the hot gas bypass pipe and is used to monitor the pressure of the hot gas bypass pipe.

[0012] The single-machine two-stage compression refrigeration system with external circulation of the embodiment of the utility model is provided with a high-pressure liquid reservoir for storing high-pressure liquid refrigerant between the condenser and the intercooler, and a hot gas bypass pipeline connecting the high-pressure liquid reservoir and the first-stage air intake of the single-machine two-stage compressor, so that the high-pressure saturated refrigerant vapor in the high-pressure liquid reservoir can be bypassed to the first-stage air intake of the single-machine two-stage compressor through the hot gas bypass pipeline, as a supplement to the refrigerant vapor from the evaporator, ensuring that the suction pressure of the first-stage air intake is not lower than the set threshold, effectively avoiding the frequent start and stop of the compressor due to too low suction pressure, and can extend the service life of the compressor, while improving system performance and reducing system energy consumption. In addition, a hot gas bypass regulating valve is used to adjust the hot gas bypass amount, and then adjust the pressure of the mixed steam input to the first-stage air intake, so that the flexibility and adaptability of the pressure regulation are stronger, and the smooth operation of the compressor in a larger load range is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of a single-machine two-stage compression refrigeration system with external circulation according to an embodiment of the utility model.

[0014] Reference numerals:

[0015] Single-machine two-stage compressor 1, condenser 2, high-pressure liquid storage tank 3, intercooler 4, evaporator 5, hot gas bypass pipeline 6, hot gas bypass regulating valve 61, heat recovery heat exchanger 7, first pipeline 81, second pipeline 82, first throttling device 83, second throttling device 84, solenoid valve 85, gas-liquid separator 9, oil separator 10, first pressure sensor 11, second pressure sensor 12. DETAILED DESCRIPTION

[0016] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention.

[0017] Refer to the following Figure 1 The single-machine two-stage compression refrigeration system with external circulation of the embodiment of the utility model is described. The single-machine two-stage compression refrigeration system comprises: a single-machine two-stage compressor 1, a condenser 2, a high-pressure liquid storage tank 3, an intercooler 4, an evaporator 5, a hot gas bypass pipeline 6 and a hot gas bypass regulating valve 61.

[0018] The single-unit two-stage compressor 1 is used to compress the refrigerant vapor, and the single-unit two-stage compressor 1 has a primary air intake port, a secondary air intake port and a high-pressure exhaust port. Among them, the primary air intake port is used to input the refrigerant vapor into the primary compression chamber of the single-unit two-stage compressor 1, and the refrigerant vapor is first compressed in the primary compression chamber to form the primary compressed refrigerant vapor; the secondary air intake port is used to input the refrigerant vapor into the secondary compression chamber of the single-unit two-stage compressor 1, and the primary compressed refrigerant vapor is discharged from the primary compression chamber, and after mixing with the refrigerant vapor input from the secondary air intake port, enters the secondary compression chamber for secondary compression to generate the secondary compressed refrigerant vapor, and the compressed secondary compressed refrigerant vapor is discharged from the high-pressure exhaust port.

[0019] The high-pressure exhaust port of the single-unit two-stage compressor 1 is connected to the inlet of the condenser 2, so as to input the compressed secondary compressed refrigerant vapor into the condenser 2. The condenser 2 is used to condense the secondary compressed refrigerant vapor and convert the secondary compressed refrigerant vapor into liquid refrigerant.

[0020] The outlet of the condenser 2 is connected to the inlet of the high-pressure liquid accumulator 3 so as to input the condensed liquid refrigerant into the high-pressure liquid accumulator 3. The high-pressure liquid accumulator 3 is used to store high-pressure liquid refrigerant. In the high-pressure liquid accumulator 3, above the liquid level of the high-pressure liquid refrigerant, there is also high-pressure saturated refrigerant vapor evaporated from the high-pressure liquid refrigerant. The high-pressure liquid accumulator 3 has a liquid outlet for outputting the high-pressure liquid refrigerant and a steam outlet for outputting the high-pressure saturated refrigerant vapor.

[0021] Among them, the intercooler 4 has a first heat exchange flow channel and a second heat exchange flow channel, the liquid outlet of the high-pressure liquid reservoir 3 is connected to the inlet of the first heat exchange flow channel and the inlet of the second heat exchange flow channel of the intercooler 4 through the first pipeline 81 and the second pipeline 82 respectively, the first pipeline 81 and the second pipeline 82 are connected in parallel, and the first pipeline 81 is provided with a first throttling device 83. In other words, the first pipeline 81 is connected between the liquid outlet of the high-pressure liquid reservoir 3 and the inlet of the first heat exchange flow channel of the intercooler 4, and the second pipeline 82 is connected between the liquid outlet of the high-pressure liquid reservoir 3 and the inlet of the second heat exchange flow channel of the intercooler 4. The first throttling device 83 on the first pipeline 81 is used to throttle the high-pressure liquid refrigerant flowing in the first pipeline 81 to turn it into a low-pressure liquid refrigerant. It can be understood that the "high pressure" and "low pressure" described here are relative concepts, "high pressure" means relatively high pressure, and "low pressure" means relatively low pressure.

[0022] Optionally, the first throttling device 83 is a thermal expansion valve or a solenoid valve, or other devices that can play a throttling role. Figure 1 In the illustrated embodiment, the first throttling device 83 is a solenoid valve.

[0023] A portion of the high-pressure liquid refrigerant discharged from the liquid outlet of the high-pressure liquid accumulator 3 is input into the first pipeline 81, and after being throttled by the throttling device on the first pipeline 81, is input into the first heat exchange flow channel of the intercooler 4; another portion of the high-pressure liquid refrigerant discharged from the liquid outlet of the high-pressure liquid accumulator 3 is input into the second pipeline 82, and is input into the second heat exchange flow channel of the intercooler 4 through the second pipeline 82. The liquid refrigerant input into the first heat exchange flow channel evaporates and cools in the intercooler 4 to cool the liquid refrigerant in the second heat exchange flow channel, so that the liquid refrigerant in the second heat exchange flow channel is supercooled.

[0024] The outlet of the first heat exchange flow channel of the intercooler 4 is connected to the secondary air intake port of the single-unit two-stage compressor 1, so as to input refrigerant vapor into the single-unit two-stage compressor 1. The outlet of the second heat exchange flow channel of the intercooler 4 is connected to the inlet of the evaporator 5 through the second throttling device 84. The supercooled liquid refrigerant discharged from the second heat exchange flow channel of the intercooler 4 is throttled by the second throttling device 84 and then input into the evaporator 5. The liquid refrigerant evaporates in the evaporator 5 to provide cooling capacity.

[0025] Optionally, the second throttling device 84 is a thermal expansion valve or a solenoid valve, or other devices that can play a throttling role. Figure 1 In the illustrated embodiment, the second throttling device 84 is a thermal expansion valve.

[0026] The outlet of the evaporator 5 is connected to the primary suction port of the single-unit two-stage compressor 1 to input refrigerant vapor into the single-unit two-stage compressor 1. The refrigerant vapor input from the primary suction port is compressed in the single-unit two-stage compressor 1 to form primary compressed refrigerant vapor. The primary compressed refrigerant vapor is mixed with the refrigerant vapor entering from the secondary suction port and then compressed in the secondary direction to form secondary compressed refrigerant vapor.

[0027] The hot gas bypass pipeline 6 connects the steam outlet of the high-pressure liquid accumulator 3 with the primary suction port of the single-machine two-stage compressor 1. The hot gas bypass pipeline 6 is used to input the high-pressure saturated refrigerant vapor in the high-pressure liquid accumulator 3 into the primary suction port of the single-machine two-stage compressor 1, so that the suction pressure at the primary suction port of the single-machine two-stage compressor 1 is not lower than the set threshold. In other words, the steam outlet of the high-pressure liquid accumulator 3 is connected with the primary suction port of the single-machine two-stage compressor 1 through the hot gas bypass pipeline 6, so as to input the high-pressure saturated refrigerant vapor to the single-machine two-stage compressor 1 through the primary suction port, and the high-pressure saturated refrigerant vapor is mixed with the refrigerant vapor from the evaporator 5 to form a mixed vapor, which is input into the single-machine two-stage compressor 1 through the primary suction port. The high-pressure saturated refrigerant vapor serves as a supplement to the refrigerant vapor of the evaporator 5, ensuring that the vapor pressure of the mixed vapor is not lower than the set threshold, effectively avoiding the problem that the suction pressure at the primary suction port is lower than the threshold, resulting in frequent shutdown of the compressor. Furthermore, since the condensing temperature is lower than the exhaust temperature, the input of high-pressure saturated refrigerant vapor into the single-unit two-stage compressor 1 will not cause the exhaust temperature of the single-unit two-stage compressor 1 to be too high, thereby ensuring the normal operation of the single-unit two-stage compressor 1.

[0028] The hot gas bypass regulating valve 61 is arranged on the hot gas bypass pipeline 6, and is used to adjust the hot gas bypass amount in the hot gas bypass pipeline 6, and then adjust the steam pressure of the mixed steam, which can better ensure that the suction pressure at the primary suction port is not lower than the set threshold. For example, if the refrigeration load is reduced to a certain extent, the refrigerant vapor pressure from the evaporator 5 is lower than the threshold of the suction pressure, and the hot gas bypass regulating valve 61 is adjusted to increase the hot gas bypass amount, to ensure that the steam pressure of the mixed steam is not lower than the set threshold, and to avoid the compressor from shutting down; if the refrigeration load increases, the refrigerant vapor pressure from the evaporator 5 increases, and the hot gas bypass regulating valve 61 can be adjusted to reduce the hot gas bypass amount.

[0029] The operation process of the single-machine two-stage compression refrigeration system with external circulation in the embodiment of the utility model is as follows:

[0030] like Figure 1As shown, the secondary compressed refrigerant vapor compressed by the single-unit two-stage compressor 1 enters the condenser 2 and is condensed into liquid refrigerant, and the liquid refrigerant is input into the high-pressure liquid storage tank 3 for storage. The liquid refrigerant output from the high-pressure liquid storage tank 3 is respectively input into the intercooler 4 from the first pipeline 81 and the second pipeline 82 and is heat exchanged in the intercooler 4. The supercooled refrigerant after heat exchange enters the evaporator 5 for evaporative cooling. The refrigerant vapor after heat exchange is input into the secondary suction port of the single-unit two-stage compressor 1, mixed with the primary compressed refrigerant vapor, and then subjected to secondary compression to be compressed into secondary compressed refrigerant vapor.

[0031] The refrigerant vapor discharged from the evaporator 5 is input from the primary suction port to the single-unit two-stage compressor 1 for primary compression. If the pressure of the refrigerant vapor discharged from the evaporator 5 is lower than the set threshold of the suction pressure of the primary suction port, the hot gas bypass regulating valve 61 is opened to allow the high-pressure saturated refrigerant vapor in the high-pressure liquid storage tank 3 to be transported to the primary suction port of the single-unit two-stage compressor 1 through the hot gas bypass pipeline 6 and mixed with the refrigerant vapor discharged from the evaporator 5 to ensure that the suction pressure at the primary suction port is not lower than the set threshold. In addition, the hot gas bypass regulating valve 61 can be adaptively adjusted according to the change in the vapor pressure of the refrigerant vapor discharged from the evaporator 5 to adjust the hot gas bypass amount and the suction pressure at the primary suction port.

[0032] The single-machine two-stage compression refrigeration system with external circulation of the embodiment of the utility model is provided with a high-pressure liquid reservoir for storing high-pressure liquid refrigerant between the condenser and the intercooler, and a hot gas bypass pipeline connecting the high-pressure liquid reservoir and the first-stage air intake of the single-machine two-stage compressor, so that the high-pressure saturated refrigerant vapor in the high-pressure liquid reservoir can be bypassed to the first-stage air intake of the single-machine two-stage compressor through the hot gas bypass pipeline, as a supplement to the refrigerant vapor from the evaporator, ensuring that the suction pressure of the first-stage air intake is not lower than the set threshold, effectively avoiding the frequent start and stop of the compressor due to too low suction pressure, and can extend the service life of the compressor, while improving system performance and reducing system energy consumption. In addition, a hot gas bypass regulating valve is used to adjust the hot gas bypass amount, and then adjust the pressure of the mixed steam input to the first-stage air intake, so that the flexibility and adaptability of the pressure regulation are stronger, and the smooth operation of the compressor in a larger load range is achieved.

[0033] Through experimental verification, it was found that compared with the refrigeration cycle system that does not use the hot gas bypass pipeline, in the single-machine two-stage compression refrigeration system with external circulation in the embodiment of the utility model, the single-machine two-stage compressor operates smoothly, the performance of the entire refrigeration system is significantly improved, and the energy consumption is significantly reduced.

[0034] In some embodiments, Figure 1As shown, the single-unit two-stage compression refrigeration system further includes a regenerative heat exchanger 7, which has a cold side and a hot side, wherein the hot side of the regenerative heat exchanger 7 is connected between the high-pressure liquid storage tank 3 and the intercooler 4, and the cold side of the regenerative heat exchanger 7 is connected between the evaporator 5 and the single-unit two-stage compressor 1. In the regenerative heat exchanger 7, the refrigerant vapor on the cold side exchanges heat with the liquid refrigerant on the hot side, and the refrigerant vapor cools the liquid refrigerant. As a result, the temperature of the liquid refrigerant decreases, and the temperature of the refrigerant vapor increases.

[0035] Optionally, the heat recovery exchanger 7 is a plate heat exchanger.

[0036] As an example, Figure 1 As shown, the hot side outlet of the heat exchanger 7 is connected to each of the first pipeline 81 and the second pipeline 82. A portion of the liquid refrigerant discharged from the hot side outlet of the heat exchanger 7 after heat exchange passes through the first pipeline 81 and is throttled and depressurized by the first throttling device 83 on the first pipeline 81 and then input into the first heat exchange flow channel of the intercooler 4, and the other portion is input into the second heat exchange flow channel of the intercooler 4 through the second pipeline 82. In the intercooler 4, the refrigerant in the first heat exchange flow channel evaporates and cools the liquid refrigerant in the second heat exchange flow channel, so that the liquid refrigerant is supercooled. The refrigerant vapor discharged from the first heat exchange flow channel of the intercooler 4 is input into the secondary air intake port of the single-unit two-stage compressor 1, and the supercooled refrigerant discharged from the second heat exchange flow channel of the intercooler 4 passes through the second throttling device 84 and is throttled and depressurized and then enters the evaporator 5 for evaporation and refrigeration.

[0037] like Figure 1 As shown, a solenoid valve 85 is further provided between the hot side outlet of the intercooler 4 and the evaporator 5 , and the solenoid valve 85 is used to control the flow of the supercooled refrigerant.

[0038] In some embodiments, the single-unit two-stage compression refrigeration system further includes a gas-liquid separator 9, which is disposed between the evaporator 5 and the single-unit two-stage compressor 1. The gas-liquid separator 9 is used to separate the liquid refrigerant from the refrigerant vapor discharged from the evaporator 5, and the vapor outlet of the gas-liquid separator 9 is connected to the first-stage suction port of the single-unit two-stage compressor 1.

[0039] exist Figure 1 In the specific embodiment shown, the gas-liquid separator 9 is arranged between the evaporator 5 and the heat recovery exchanger 7, and the heat recovery exchanger 7 is located downstream of the gas-liquid separator 9. The steam outlet of the gas-liquid separator 9 is connected to the cold side inlet of the heat recovery exchanger 7 to input the refrigerant vapor after gas-liquid separation into the cold side of the heat recovery exchanger 7.

[0040] In some embodiments, Figure 1As shown, the single-unit two-stage compression refrigeration system further includes an oil separator 10, which is disposed between the high-pressure exhaust port of the single-unit two-stage compressor 1 and the condenser 3, and is used to separate the lubricating oil from the secondary compressed refrigerant vapor discharged from the high-pressure exhaust port. The oil outlet of the oil separator 10 is connected to the oil inlet of the single-unit two-stage compressor 1, so as to return the separated lubricating oil to the single-unit two-stage compressor 1.

[0041] In some embodiments, Figure 1 As shown, the single-unit two-stage compression refrigeration system also includes a first pressure sensor 11, which is used to monitor the suction pressure at the first suction port of the single-unit two-stage compressor 1. The first pressure sensor 11 is connected to the hot gas bypass regulating valve 61 signal so as to adjust the opening of the hot gas bypass regulating valve 61 according to the pressure monitoring value of the first pressure sensor 11, thereby adjusting the suction pressure of the single-unit two-stage compressor 1 and maintaining the normal operation of the system. In actual application, a PLC controller can be used to adjust the opening of the hot gas bypass regulating valve 61 through PID control.

[0042] Specifically, when the first pressure sensor 11 detects that the suction pressure at the first-stage suction port of the single-unit two-stage compressor 1 drops below a preset threshold, the hot gas bypass regulating valve 61 is adjusted to open, and the high-pressure saturated refrigerant vapor in the high-pressure liquid storage tank 3 is mixed with the refrigerant vapor from the evaporator 5 and then input into the single-unit two-stage compressor 1, so that the suction pressure at the first-stage suction port is not lower than the set threshold.

[0043] It should be noted that the set threshold of the suction pressure at the first-stage suction port refers to the shutdown threshold of the single-machine two-stage compressor 1, which can make the preset threshold of the suction pressure at the first-stage suction port higher than the set threshold, thereby effectively avoiding the shutdown of the single-machine two-stage compressor 1.

[0044] If the first pressure sensor 11 detects that the suction pressure is further reduced, the opening of the hot gas bypass regulating valve 61 is adjusted to increase, and the hot gas bypass amount is increased to ensure the normal operation of the single-unit two-stage compressor 1 and avoid shutdown. When the first pressure sensor 11 detects that the suction pressure of the first-stage suction port of the single-unit two-stage compressor 1 increases, the opening of the hot gas bypass regulating valve 61 is adjusted to decrease until it is closed, and the hot gas bypass amount is reduced.

[0045] In some embodiments, Figure 1 As shown, the single-machine two-stage compression refrigeration system further includes a second pressure sensor 12, which is arranged on the hot gas bypass pipe 6 and is used to monitor the pressure of the hot gas bypass pipe 6. A signal connection is made between the second pressure sensor 12 and the hot gas bypass regulating valve 61, and when adjusting the opening of the hot gas bypass regulating valve 61, the pressure detection value of the second pressure sensor 12 can be referred to.

[0046] When selecting equipment for a single-machine two-stage compression refrigeration system, it is necessary to select equipment with appropriate power through load calculation.

[0047] In a single-machine two-stage compression refrigeration system, the joints between the pipeline and the equipment should be well sealed, and it is preferred to conduct a vacuum and pressure-maintaining test for 48 hours to ensure that the system is leak-free.

[0048] Preferably, the joints between the pipeline and the equipment are well sealed, and dry nitrogen is filled into the system, with 1.05MPa for the low-pressure part and 2.30MPa for the high-pressure part. Check for leaks, and after the pressure stabilizes, maintain it for 24 hours to eliminate the influence of temperature and there is no pressure drop.

[0049] Preferably, pressure protection is designed, high pressure: 2.3±0.05MPa, stop alarm, manual reset; low pressure: 0.03±0.02MPa, disconnect, 0.23±0.02MPa, connect.

[0050] Preferably, pressure protection is designed, water pressure: 0.1±0.02MPa, parking alarm, automatic reset.

[0051] Preferably, the system should be tested after installation, and the compressor current and voltage should be measured. The current should not be greater than the rated current.

[0052] Preferably, the insulation resistance test: in an environment of normal temperature and relative humidity less than 83%, the hot resistance between the charged parts and the non-charged metal parts is greater than 2MΩ.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0054] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is not lower in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0057] In the present utility model, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0058] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A single-unit two-stage compression refrigeration system with external circulation, characterized in that: include: Single machine two-stage compressor, condenser, high pressure liquid receiver, intercooler, evaporator, hot gas bypass pipeline and hot gas bypass regulating valve, The single-unit two-stage compressor has a primary air intake port, a secondary air intake port and a high-pressure exhaust port, the high-pressure exhaust port is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the high-pressure liquid storage, and the high-pressure liquid storage has a liquid outlet and a steam outlet. The intercooler has a first heat exchange channel and a second heat exchange channel, the liquid outlet of the high-pressure liquid accumulator is respectively connected to the inlet of the first heat exchange channel and the inlet of the second heat exchange channel through a first pipeline and a second pipeline connected in parallel, a first throttling device is provided on the first pipeline, the outlet of the first heat exchange channel is connected to the secondary air intake port, the outlet of the second heat exchange channel is connected to the inlet of the evaporator through a second throttling device, and the outlet of the evaporator is connected to the primary air intake port, The hot gas bypass pipeline is connected to the steam outlet of the high-pressure liquid storage device and the first-stage air intake port, and the hot gas bypass regulating valve is arranged on the hot gas bypass pipeline.

2. The single-unit two-stage compression refrigeration system with external circulation according to claim 1 is characterized in that: The single-machine two-stage compression refrigeration system includes a heat recovery heat exchanger, a hot side of the heat recovery heat exchanger is connected between the high-pressure liquid storage tank and the intercooler, and a cold side of the heat recovery heat exchanger is connected between the evaporator and the primary air intake port.

3. The single-unit two-stage compression refrigeration system with external circulation according to claim 2 is characterized in that: The regenerative heat exchanger is a plate heat exchanger.

4. The single-unit two-stage compression refrigeration system with external circulation according to claim 1 is characterized in that: The single-machine two-stage compression refrigeration system comprises a gas-liquid separator, and the gas-liquid separator is connected between the evaporator and the primary air intake port.

5. The single-unit two-stage compression refrigeration system with external circulation according to claim 2 is characterized in that: The single-machine two-stage compression refrigeration system comprises a gas-liquid separator, which is connected between the evaporator and the cold side inlet of the heat recovery heat exchanger.

6. The single-unit two-stage compression refrigeration system with external circulation according to claim 1 is characterized in that: It also includes an oil separator, which is arranged between the high-pressure exhaust port of the single-unit two-stage compressor and the condenser.

7. A single-unit two-stage compression refrigeration system with external circulation according to any one of claims 1 to 6, characterized in that: It also includes a first pressure sensor, which is used to monitor the suction pressure of the first-stage suction port of the single-machine two-stage compressor. The first pressure sensor is connected to the hot gas bypass regulating valve signal so as to adjust the opening of the hot gas bypass regulating valve according to the pressure monitoring value of the first pressure sensor.

8. The single-unit two-stage compression refrigeration system with external circulation according to any one of claims 1 to 6, characterized in that: It also includes a second pressure sensor, which is arranged on the hot gas bypass pipe and is used to monitor the pressure of the hot gas bypass pipe.

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