Refrigerant circulating system

Abstract

The utility model relates to the technical field of air conditioners, and discloses a refrigerant circulating system which comprises an indoor unit, an outdoor unit and a valve unit. The indoor unit comprises an indoor unit; the outdoor unit comprises a compressor, a first pipeline, a second pipeline, a throttling device, a first outdoor heat exchanger, a third pipeline, a fourth pipeline, a gas-liquid separator, a fifth pipeline and a second outdoor heat exchanger; the valve unit comprises a first valve, a second valve, a third valve and a fourth valve, the first valve is installed on the first pipeline, the second valve is installed on the second pipeline, and the second outdoor heat exchanger is located between the third valve and the fourth valve; through the fifth pipeline, the second outdoor heat exchanger, the first valve, the second valve, the third valve and the fourth valve, internal circulation of the refrigerant in the outdoor unit can be achieved, the circulation path of the refrigerant is shortened, the temperature of the refrigerant is rapidly increased, the refrigerant is separated from engine oil, sufficient lubrication is provided for a compressor, mechanical noise is reduced, and the service life of the compressor is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to air conditioning technical field especially is related to a refrigerant circulation system. BACKGROUND

[0002] In the existing refrigerant circulation system, there is a more prominent problem; when the compressor starts initially, the mixture of oil and refrigerant in the compressor body will be discharged in large quantities from the compressor body; because the indoor unit and the outdoor unit are connected through a long pipeline, the refrigerant and oil discharged from the compressor of the outdoor unit need to pass through a long pipeline into the indoor unit, and then circulate back into the compressor of the outdoor unit; this process causes the discharged oil to be difficult to return to the compressor in a short time, and the flow of refrigerant in the long circulation pipeline produces a large amount of energy loss, resulting in low refrigerant temperature, and the mutual solubility of the low-temperature refrigerant and the oil is high, so the oil in the compressor body will be excessively diluted due to the mutual solubility with the refrigerant, resulting in a significant reduction in oil concentration; when the refrigerant dissolution amount in the oil is too high, during the operation of the compressor, the lubrication film thickness of the core components (such as bearings, sliding sheets, etc.) will be thinned due to the decrease in oil viscosity, and even local dry friction phenomenon will occur, thereby causing abnormal wear, increased mechanical noise, and shortened service life, etc.

[0003] In the prior art, although there are schemes for improving oil concentration by optimizing oil return control or wrapping the compressor with an electric heating band, these methods generally have limitations such as slow response speed, high energy consumption, or complex structure, and cannot quickly restore the concentration of refrigeration oil under low-temperature start-up or defrosting transient conditions, resulting in challenges to the reliability of the system. UTILITY MODEL CONTENT

[0004] To solve at least one of the technical problems existing in the prior art, the utility model aims to provide a refrigerant circulation system that helps to reduce mechanical noise and prolong the service life of the compressor, and improve the reliability of the system.

[0005] In order to achieve the above object, the utility model provides a kind of refrigerant circulation system, including indoor unit, outdoor unit and valve unit;Indoor unit includes indoor machine;Outdoor unit includes compressor, first pipeline, second pipeline, throttling device, first outdoor heat exchanger, third pipeline, fourth pipeline, gas-liquid separator, fifth pipeline and second outdoor heat exchanger, the import end of the first pipeline is communicated with the outer tube of the compressor, the export end of the first pipeline is communicated with the indoor machine, the import end of the second pipeline is communicated with the indoor machine, the first outdoor heat exchanger is installed in the second pipeline, the throttling device is installed in the second pipeline and between the first outdoor heat exchanger and the indoor machine, the export end of the second pipeline is communicated with the import end of the third pipeline, the export end of the third pipeline is communicated with the gas-liquid separator, the import end of the fourth pipeline is communicated with the gas-liquid separator, the export end of the fourth pipeline is communicated with the compressor, the import end of the fifth pipeline is communicated with the first pipeline, the export end of the fifth pipeline is communicated with the second pipeline and between the indoor machine and the throttling device, the second outdoor heat exchanger is installed in the fifth pipeline;Valve unit includes first valve, second valve, third valve and fourth valve, the first valve is installed in the first pipeline and between the import end of the fifth pipeline and the indoor machine, the second valve is installed in the second pipeline and between the export end of the fifth pipeline and the indoor machine, the third valve and the fourth valve are both installed in the fifth pipeline, and the second outdoor heat exchanger is between the third valve and the fourth valve.

[0006] In some embodiments, the refrigerant circulation system further comprises a first long connection pipe and a second long connection pipe, the export end of the first pipeline is connected to the indoor machine through the first long connection pipe, and the import end of the second pipeline is connected to the indoor machine through the first long connection pipe.

[0007] In some embodiments, the refrigerant circulation system further comprises a four-way valve, a first valve port of the four-way valve is connected to the outer tube of the compressor, a second valve port of the four-way valve is connected to the import end of the first pipeline, a third valve port of the four-way valve is connected to the export end of the second pipeline, and a fourth valve port of the four-way valve is connected to the import end of the third pipeline.

[0008] In some embodiments, the refrigerant circulation system further comprises a silencer, the silencer is installed in the first pipeline, and the import end of the fifth pipeline is between the silencer and the first valve.

[0009] In some embodiments, the number of compressors is multiple.

[0010] In some embodiments, the refrigerant circulation system further comprises a bypass unit, the bypass unit comprising a bypass main pipe and a bypass main valve, the bypass main valve being installed on the bypass main pipe, an inlet end of the bypass main pipe being communicated with the third pipeline, and an outlet end of the bypass main pipe being communicated with the compressor.

[0011] In some embodiments, the number of the compressors is multiple; the bypass unit further comprises multiple bypass branch pipes and multiple bypass branch valves, one bypass branch pipe being installed with one bypass branch valve, and the bypass main pipe being communicated with the multiple compressors through the multiple bypass branch pipes.

[0012] In some embodiments, the refrigerant circulation system further comprises an oil separator and an oil return capillary, the oil separator being installed on an extension pipe of the compressor, an inlet end of the oil return capillary being communicated with the oil separator, and an outlet end of the oil return capillary being communicated with the fourth pipeline.

[0013] Optionally, the compressor is a rotary compressor or a scroll compressor.

[0014] In some embodiments, the throttling device is a throttle valve.

[0015] Compared with the prior art, the refrigerant circulation system has the following beneficial effects: (1) when the compressor is started in a low-temperature working condition or a defrosting working condition, the first valve and the second valve are closed, the third valve and the fourth valve are opened, the refrigerant does not pass through the indoor unit, but directly reaches the second pipeline, the third pipeline and the fourth pipeline through the fifth pipeline, returns to the compressor and sequentially passes through the second outdoor heat exchanger, the throttling device and the first outdoor heat exchanger through the above pipelines, the refrigerant is internally circulated in the outdoor unit, the circulation path of the refrigerant is shortened, the energy loss of the refrigerant in the flow process is reduced, the energy generated by the work of the compressor is used to heat the refrigerant itself to increase the temperature of the refrigerant, the separated oil is more easily deposited at the bottom of the compressor and provides sufficient lubrication for the movement of the core components of the compressor, thereby avoiding abnormal wear of the core components of the compressor, reducing mechanical noise and prolonging the service life of the compressor.

[0016] (2), compared with the prior art, the refrigerant circulation system provided by the utility model improves the oil concentration through optimizing oil return control or adopting electric heating and the like, the refrigerant circulation system provided by the utility model can quickly adjust the refrigerant circulation path through simple valve control, the concentration of refrigeration machine oil can be quickly recovered under low-temperature starting or defrosting and the like transient working conditions, the response speed is faster, complex control logic and additional high-energy-consumption equipment are not needed, the system structure is simplified, the complexity and fault points of the system are reduced, the equipment cost and maintenance cost are reduced, the reliability and economy of the system are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is a structure schematic view of a refrigerant circulation system provided by the utility model embodiment;

[0018] Fig. 2 is a connection schematic view of an outdoor unit and a valve unit provided by the utility model embodiment;

[0019] Fig. 3 is a connection schematic view of an outdoor unit and a bypass unit provided by the utility model embodiment.

[0020] In the drawing, 1, indoor unit; 11, indoor machine;

[0021] 2, outdoor unit; 21, compressor; 22, throttling device; 23, first outdoor heat exchanger; 24, gas-liquid separator; 25, second outdoor heat exchanger; 211, outer extension pipe;

[0022] 201, first pipe; 202, second pipe; 203, third pipe; 204, fourth pipe; 205, fifth pipe;

[0023] 3, valve unit; 301, first valve; 302, second valve; 303, third valve; 304, fourth valve;

[0024] 4, first long union pipe;

[0025] 5, second long union pipe;

[0026] 6, four-way valve;

[0027] 7, bypass unit; 71, bypass main pipe; 72, bypass main valve; 73, bypass branch pipe; 74, bypass branch valve;

[0028] 8, oil separator;

[0029] 9, silencer. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application will be further described in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application.

[0031] The terms "first", "second", "third", etc. are used only for the purpose of description and are not to be construed as indicating or implying relative importance or a specific number of features indicated. Thus, features defined with "first", "second" or "third" can explicitly or implicitly include one or more of the features.

[0032] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] In the present application, unless specifically defined and limited otherwise, the first feature "on" or "under" the second feature can include the direct contact of the first and second features, or it can include the contact of the first and second features through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes the first feature directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0034] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by those skilled in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application; the terms "include" and "have" in the specification and claims of the present application and above description of drawings are intended to cover non-exclusive inclusion.

[0035] In the present application, the phrase "embodiment" means that the specific features, structures or properties described in conjunction with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily refer to the same embodiment, nor is it independent or alternative to other embodiments.

[0036] As Figs. 1-3As shown, the utility model embodiment preferably comprises a refrigerant circulation system, which comprises an indoor unit 1, an outdoor unit 2 and a valve unit 3.

[0037] The indoor unit 1 comprises an indoor unit 1.

[0038] The outdoor unit 2 comprises a compressor 21, a first pipeline 201, a second pipeline 202, a throttling device 22, a first outdoor heat exchanger 23, a third pipeline 203, a fourth pipeline 204, a gas-liquid separator 24, a fifth pipeline 205 and a second outdoor heat exchanger 25, the inlet end of the first pipeline 201 is communicated with the outer extension pipe 211 of the compressor 21, the outlet end of the first pipeline 201 is communicated with the indoor unit 11, the inlet end of the second pipeline 202 is communicated with the indoor unit 11, the first outdoor heat exchanger 23 is installed on the second pipeline 202, the throttling device 22 is installed on the second pipeline 202 and located between the first outdoor heat exchanger 23 and the indoor unit 11, the outlet end of the second pipeline 202 is communicated with the inlet end of the third pipeline 203, the outlet end of the third pipeline 203 is communicated with the gas-liquid separator 24, the inlet end of the fourth pipeline 204 is communicated with the gas-liquid separator 24, the outlet end of the fourth pipeline 204 is communicated with the compressor 21, the inlet end of the fifth pipeline 205 is communicated with the first pipeline 201, the outlet end of the fifth pipeline 205 is communicated with the second pipeline 202 and located between the indoor unit 11 and the throttling device 22, and the second outdoor heat exchanger 25 is installed on the fifth pipeline 205.

[0039] The valve unit 3 comprises a first valve 301, a second valve 302, a third valve 303 and a fourth valve 304, the first valve 301 is installed on the first pipeline 201 and located between the inlet end of the fifth pipeline 205 and the indoor unit 11, the second valve 302 is installed on the second pipeline 202 and located between the outlet end of the fifth pipeline 205 and the indoor unit 11, the third valve 303 and the fourth valve 304 are both installed on the fifth pipeline 205, and the second outdoor heat exchanger 25 is located between the third valve 303 and the fourth valve 304.

[0040] Based on the technical scheme, when the compressor 21 is started in the low-temperature working condition or the defrosting working condition, the first valve 301 and the second valve 302 are closed, the third valve 303 and the fourth valve 304 are opened, the refrigerant does not pass through the indoor unit 1, but directly reaches the second pipeline 202, the third pipeline 203 and the fourth pipeline 204 through the fifth pipeline 205, returns to the compressor 21 and sequentially passes through the second outdoor heat exchanger 25, the throttling device 22 and the first outdoor heat exchanger 23 through the above pipelines, the internal circulation of the refrigerant in the outdoor unit 2 is realized, the circulation path of the refrigerant can be shortened, the energy loss of the refrigerant in the flow process is reduced, the energy generated by the work of the compressor is used to heat the refrigerant itself to increase the temperature of the refrigerant, the refrigerant is separated from the oil after the temperature is increased, the separated oil is more easily deposited at the bottom of the compressor and provides sufficient lubrication for the movement of the core components of the compressor, and then the abnormal wear of the core components of the compressor 21 can be avoided, which is helpful to reduce the mechanical noise and prolong the service life of the compressor 21.

[0041] The compressor 21 works on the refrigerant in the internal circulation in the outdoor unit 2 at low temperature, can quickly heat and activate most of the refrigerant, so that the refrigerant is separated from the oil due to the rapid temperature rise, the oil can return to the compressor 21 in a short time and be kept in the compressor body, and the internal core components of the compressor 21 are prevented from being abnormally worn. The superheat TdSH is calculated by detecting the exhaust temperature of the compressor, if TdSH>10K, it can be judged that the refrigerant is completely activated, the first valve 301 and the second valve 302 are opened, the third valve 303 and the fourth valve 304 are closed, and the refrigerant circulation system is switched to the large circulation process of the communication between the indoor unit 1 and the outdoor unit 2, if the large circulation process of the communication between the indoor unit 1 and the outdoor unit 2 appears TdSH≤10K, the first valve 301 and the second valve 302 are closed again, the third valve 303 and the fourth valve 304 are opened, and the refrigerant circulation system is switched to the small circulation process of the outdoor unit.

[0042] Compared with the scheme for improving the oil concentration by optimizing the oil return control or adopting electric heating in the prior art, the refrigerant circulation system provided by the utility model can quickly adjust the refrigerant circulation path through simple valve control, can quickly restore the concentration of the refrigerating oil in the transient working condition such as low-temperature starting or defrosting, has a faster response speed, does not need complex control logic and additional high-energy-consumption equipment, simplifies the system structure, reduces the complexity and fault points of the system, is helpful to reduce the equipment cost and maintenance cost, improves the reliability and economy of the system.

[0043] In the embodiment, the number of indoor units 11 is four, and the four indoor units 11 are connected in parallel.

[0044] In some other implementations, the number of indoor units 11 can be any number, such as one, two, three, etc.

[0045] The indoor unit 11 is the terminal equipment in the entire air conditioning system that directly provides cooling or heating services to the indoor environment. The indoor unit 11 includes structures such as heat exchangers, throttling devices, and controllers.

[0046] Optionally, the compressor 21 is a rotary compressor or a scroll compressor.

[0047] Optionally, the number of compressors 21 may be one or more.

[0048] Optionally, when there are multiple compressors 21, any two compressors 21 can be of the same or different types; that is, all of the multiple compressors 21 can be rotary compressors, all of them can be scroll compressors, or some of the compressors 21 can be rotary compressors and the other part of the compressors 21 can be scroll compressors.

[0049] For example, in the embodiment, the throttling device 22 is a throttling valve, which can not only achieve throttling but also regulate the flow rate; for example, the throttling device 22 can also be configured as a capillary tube.

[0050] See Fig. 1 The outdoor side of the frame enclosed by the dashed lines refers to the equipment and components located outdoors; the inner side of the frame enclosed by the dashed lines refers to the equipment and components located indoors. See also... Figs. 1-3 The arrows on the pipes in the diagram indicate the direction of fluid flow within the pipes.

[0051] In this embodiment, the first valve 301 and the second valve 302 are regulating valves, and the third valve 303 and the fourth valve 304 are shut-off valves.

[0052] See Figs. 1-2 The refrigerant circulation system provided in this embodiment of the invention further includes a first long connecting pipe 4 and a second long connecting pipe 5. The outlet end of the first pipe 201 is connected to the indoor unit 11 via the first long connecting pipe 4, and the inlet end of the second pipe 202 is connected to the indoor unit 11 via the second long connecting pipe 5. The first long connecting pipe 4 and the second long connecting pipe 5 are relatively long pipes connecting the indoor unit 1 and the outdoor unit 2. The first long connecting pipe 4 and the first pipe 201 can be different parts of a single integrally formed pipe, or they can be two different pipes connected together. Similarly, the second long connecting pipe 5 and the second pipe 202 can be different parts of a single integrally formed pipe, or they can be two different pipes connected together.

[0053] The use of the first long connecting pipe 4 and the second long connecting pipe 5 makes the connection between the indoor unit 1 and the outdoor unit 2 more flexible. In actual installation scenarios, whether the indoor and outdoor units are far apart in large buildings or the complex spatial layout has special requirements for the pipe routing, the connection between the indoor unit 11 and the outdoor unit 2 can be easily achieved through these two long connecting pipes, meeting the needs of different installation environments and improving the applicability of the refrigerant circulation system.

[0054] The refrigerant circulation system also includes a four-way valve 6. The first port of the four-way valve 6 is connected to the extended pipe 211 of the compressor 21, the second port is connected to the inlet end of the first pipe 201, the third port is connected to the outlet end of the second pipe 202, and the fourth port is connected to the inlet end of the third pipe 203. Compared to using multiple valves or complex piping connections to achieve refrigeration / heating mode switching, the four-way valve 6 simplifies the overall structure of the refrigerant circulation system, reduces the number of pipes and valves, lowers system complexity and potential failure points, and also reduces installation costs and maintenance difficulty.

[0055] The refrigerant circulation system also includes a silencer 9, which is installed on the first pipe 201. The inlet end of the fifth pipe 205 is located between the silencer 9 and the first valve 301. The silencer 9, installed on the first pipe 201, effectively suppresses the noise generated by the high-speed flow of refrigerant within the pipe. During the operation of the refrigerant circulation system, after the refrigerant is discharged from the compressor 21, it passes through the first pipe 201 at high speed, generating significant airflow noise. The silencer 9, through its special structure and sound-absorbing materials, absorbs and converts this noise energy, thereby reducing the noise generated during the operation of the entire system and creating a quieter and more comfortable operating environment for users.

[0056] See Fig. 1 and Fig. 3 The refrigerant circulation system provided in this embodiment of the invention also includes a bypass unit 7, which includes a bypass main pipe 71 and a bypass main valve 72. The bypass main valve 72 is installed on the bypass main pipe 71. The inlet end of the bypass main pipe 71 is connected to the third pipe 203, and the outlet end of the bypass main pipe 71 is connected to the compressor 21. The refrigerant circulation system operates under complex and variable conditions. The bypass unit 7 provides the refrigerant circulation system with greater adaptability. When the ambient temperature changes or the system operating mode switches, adjusting the refrigerant flow rate of the bypass main pipe 71 can quickly balance the system pressure and temperature, enabling the system to rapidly adapt to new operating conditions, reducing large fluctuations in pressure and temperature, ensuring the system always operates at high efficiency, and improving overall operating performance.

[0057] The system comprises multiple compressors 21. The bypass unit 7 also includes multiple bypass branch pipes 73 and multiple bypass branch valves 74. Each bypass branch pipe 73 is equipped with a bypass branch valve 74. The main bypass pipe 71 is connected to each of the multiple compressors 21 through the multiple bypass branch pipes 73. The multiple compressors 21, in conjunction with the multiple bypass branch pipes 73 and bypass branch valves 74, enable precise and independent control of the refrigerant flow to each compressor 21. Under different operating conditions, such as varying cooling or heating demands in different areas, the amount of refrigerant entering each compressor 21 can be precisely controlled by adjusting the corresponding bypass branch valves 74, ensuring that each compressor 21 operates under optimal conditions and improving the overall energy efficiency ratio of the system.

[0058] In this embodiment, there are two compressors 21 connected in parallel.

[0059] In some other embodiments, the number of compressors 21 can also be any number, such as one, three, four, etc.

[0060] In this embodiment, both the bypass main valve 72 and the bypass branch valve 74 are regulating valves.

[0061] The refrigerant circulation system provided in this embodiment of the present invention also includes an oil separator 8 and an oil return capillary tube 81. The oil separator 8 is installed on the outer tube 211 of the compressor 21. The inlet end of the oil return capillary tube 81 is connected to the oil separator 8, and the outlet end of the oil return capillary tube 81 is connected to the fourth pipe 204. The oil separator 8 can collect the mixture of refrigerant and oil discharged from the compressor 21 and return the oil back to the compressor 21 through the oil return capillary tube 81 and the fourth pipe 204 in sequence. This further increases the oil concentration in the compressor 21, which helps to further avoid abnormal wear of the compressor 21's core components, reduce mechanical noise, and extend the service life of the compressor 21.

[0062] Compared with the existing technology that uses an electric heating band to wrap the compressor casing to improve oil concentration (comparative example), the advantages of the refrigerant circulation system provided in this embodiment are shown in Table 1 below:

[0063]

[0064]

[0065] Table 1

[0066] In Table 1, the oil temperature heating power of 120W in the comparative example refers to the power of the electric heating belt, while the oil temperature heating power of 6000W in this embodiment refers to the sum of the power of the two compressors.

[0067] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A refrigerant circulation system, characterized in that, include: Indoor unit (1), which includes indoor unit (11); Outdoor unit (2); It includes a compressor (21), a first pipe (201), a second pipe (202), a throttling device (22), a first outdoor heat exchanger (23), a third pipe (203), a fourth pipe (204), a gas-liquid separator (24), a fifth pipe (205), and a second outdoor heat exchanger (25). The inlet end of the first pipe (201) is connected to the extension tube (211) of the compressor (21), and the outlet end of the first pipe (201) is connected to the indoor unit (11). The inlet end of the second pipe (202) is connected to the indoor unit (11). The first outdoor heat exchanger (23) is installed on the second pipe (202), and the throttling device (22) is installed on the second pipe (202) and located on the first outdoor heat exchanger (25). Between the outdoor heat exchanger (23) and the indoor unit (11), the outlet end of the second pipe (202) is connected to the inlet end of the third pipe (203), the outlet end of the third pipe (203) is connected to the gas-liquid separator (24), the inlet end of the fourth pipe (204) is connected to the gas-liquid separator (24), the outlet end of the fourth pipe (204) is connected to the compressor (21), the inlet end of the fifth pipe (205) is connected to the first pipe (201), the outlet end of the fifth pipe (205) is connected to the second pipe (202) and is located between the indoor unit (11) and the throttling device (22), and the second outdoor heat exchanger (25) is installed on the fifth pipe (205); The valve unit (3) includes a first valve (301), a second valve (302), a third valve (303), and a fourth valve (304). The first valve (301) is installed on the first pipe (201) and located between the inlet end of the fifth pipe (205) and the indoor unit (11). The second valve (302) is installed on the second pipe (202) and located between the outlet end of the fifth pipe (205) and the indoor unit (11). The third valve (303) and the fourth valve (304) are both installed on the fifth pipe (205). The second outdoor heat exchanger (25) is located between the third valve (303) and the fourth valve (304).

2. The refrigerant circulation system according to claim 1, characterized in that, It also includes a first long connecting pipe (4) and a second long connecting pipe (5). The outlet end of the first pipe (201) is connected to the indoor unit (11) through the first long connecting pipe (4), and the inlet end of the second pipe (202) is connected to the indoor unit (11) through the second long connecting pipe (5).

3. The refrigerant circulation system according to claim 1, characterized in that, It also includes a four-way valve (6), the first valve port of the four-way valve (6) is connected to the extension pipe (211) of the compressor (21), the second valve port of the four-way valve (6) is connected to the inlet end of the first pipe (201), the third valve port of the four-way valve (6) is connected to the outlet end of the second pipe (202), and the fourth valve port of the four-way valve (6) is connected to the inlet end of the third pipe (203).

4. The refrigerant circulation system according to claim 1, characterized in that, It also includes a silencer (9) installed on the first pipe (201), and the inlet end of the fifth pipe (205) is located between the silencer and the first valve (301).

5. The refrigerant circulation system according to any one of claims 1-4, characterized in that, The number of compressors (21) is multiple.

6. The refrigerant circulation system according to any one of claims 1-4, characterized in that, It also includes a bypass unit (7), which includes a bypass main pipe (71) and a bypass main valve (72). The bypass main valve (72) is installed on the bypass main pipe (71). The inlet end of the bypass main pipe (71) is connected to the third pipeline (203), and the outlet end of the bypass main pipe (71) is connected to the compressor (21).

7. The refrigerant circulation system according to claim 6, characterized in that, The number of compressors (21) is multiple; The bypass unit (7) also includes multiple bypass branch pipes (73) and multiple bypass branch valves (74). One bypass branch valve (74) is installed on each of the bypass branch pipes (73). The bypass main pipe (71) is connected to multiple compressors (21) one by one through the multiple bypass branch pipes (73).

8. The refrigerant circulation system according to claim 1, characterized in that, It also includes an oil separator (8) and an oil return capillary tube (81), wherein the oil separator (8) is installed on the extension tube (211) of the compressor (21), the inlet end of the oil return capillary tube (81) is connected to the oil separator (8), and the outlet end of the oil return capillary tube (81) is connected to the fourth pipe (204).

9. The refrigerant circulation system according to claim 1, characterized in that, The compressor (21) is a rotary compressor or a scroll compressor.

10. The refrigerant circulation system according to claim 1, characterized in that, The throttling device (22) is a throttling valve.

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