Liquid storage tank, air conditioning system and control method thereof

Abstract

The present application relates to air conditioning technical field, specifically provide a kind of liquid storage tank, air conditioning system and control method thereof;To solve the problem that effective gas-liquid separation cannot be realized in the liquid storage tank exists.The purpose for this purpose, the liquid storage tank of the present application includes tank body and first connecting pipe;The bottom of tank body is provided with first interface;First connecting pipe first end from the top of tank body into tank body, and into the lower half of tank body, and the first end of first connecting pipe is bent and arranged.When entering gas-liquid mixed refrigerant from first connecting pipe, the first end of bending is high-speed ejected;Gas-liquid mixture hits side wall.In the process of impact, liquid refrigerant will adhere to side wall and flow down due to inertia, eventually accumulated in the bottom of tank body;And gaseous refrigerant will rebound and stay in the upper space of tank body due to small density and inertia.After effective separation, the liquid refrigerant in the bottom of tank body is discharged through the first interface of tank body, which ensures the gas-liquid separation effect.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically providing a liquid storage tank, an air conditioning system, and a control method thereof. Background Technology

[0002] Water source multi-split air conditioning systems are increasingly widely used because water has a large specific heat capacity and high heat exchange efficiency, and they often use small-sized, high-efficiency plate heat exchangers. This makes the overall size of the unit relatively small, allowing it to be placed in equipment rooms with limited space.

[0003] However, plate heat exchangers are small in size and have limited internal space, making it impossible to store large amounts of refrigerant. In air conditioning cooling mode, the plate heat exchanger, acting as the condenser, is a crucial refrigerant storage location, but its small volume leads to excessively high pressure in the system when the refrigerant charge is large, resulting in system instability and increased energy consumption. Therefore, a liquid receiver tank is typically added at the condenser outlet to increase the refrigerant storage space.

[0004] The liquid receiver in the system mainly serves the following functions: First, in cooling mode, it stores the high-pressure, medium-temperature refrigerant liquid flowing from the plate heat exchanger; second, it prevents refrigerant oil from accumulating in the liquid receiver and ensures the circulation of refrigerant oil within the system; third, in heating mode, the gas-liquid mixture of refrigerant after being throttled by the electronic expansion valve separates at the bottom of the liquid receiver, with the liquid refrigerant remaining at the bottom and the gas rising to the top, thereby maximizing the amount of liquid entering the plate heat exchanger and ensuring its heat exchange efficiency. However, the existing liquid receiver structure, which uses direct alignment of the inlet and outlet, results in ineffective gas-liquid separation.

[0005] Therefore, there is an urgent need for a liquid storage tank, an air conditioning system, and a control method to solve the above-mentioned technical problems. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problem that the storage tank cannot achieve effective gas-liquid separation.

[0007] In a first aspect, the present invention provides a liquid storage tank, the liquid storage tank comprising: The tank body, wherein a first interface is provided at the bottom of the tank body; The first connecting pipe has its first end extending from the top of the tank into the tank body and into the lower half of the tank body, and the first end of the first connecting pipe is bent.

[0008] In a specific embodiment of the above-mentioned liquid storage tank, the distance between the first connecting pipe and the bottom wall of the tank is less than 1 / 3h; where h is the height of the tank.

[0009] In a specific embodiment of the above-mentioned liquid storage tank, the minimum distance between the opening at the first end of the first connecting pipe and the side wall of the tank body is greater than a first preset value; wherein, the first preset value is a constant.

[0010] In a specific embodiment of the above-described liquid storage tank, the opening at the first end of the first connecting pipe faces the side wall of the tank body; and / or The opening at the first end of the first connecting pipe is a beveled cut.

[0011] In a specific embodiment of the above-mentioned liquid storage tank, the first connecting pipe includes a first sub-pipe and a second sub-pipe, the first sub-pipe extending into one end of the second sub-pipe; the first sub-pipe is located inside the tank body, and the second sub-pipe is at least partially exposed outside the tank body.

[0012] In a specific embodiment of the above-described liquid storage tank, a second connecting pipe is further included, which is connected to the bottom end of the tank body to form a first interface at the bottom of the tank body; and / or The first connecting pipe is welded to the tank body; and / or The second connecting pipe is welded to the tank body; and / or The tank body is integrally formed.

[0013] In a second aspect, the present invention provides an air conditioning system, the air conditioning system comprising: Outdoor heat exchanger; Indoor heat exchanger; As described above, the first interface of the liquid storage tank is connected to the outdoor heat exchanger; the first end of the first connecting pipe is connected to the indoor heat exchanger.

[0014] In a specific implementation of the above-mentioned air conditioning system, a bypass branch is also included, the two ends of which are respectively connected to the first connecting pipe and the first interface; a bypass valve is provided on the bypass valve.

[0015] In a third aspect, the present invention provides a control method for an air conditioning system as described above, the control method comprising the following steps: In heating mode, the opening degree of the bypass valve is determined based on the temperature of the outdoor heat exchanger near the liquid storage tank, the compressor suction pressure, and the compressor frequency.

[0016] In a specific implementation of the control method for the aforementioned air conditioning system, "determining the opening degree of the bypass valve based on the temperature of the outdoor heat exchanger near the liquid storage tank, the compressor's suction pressure, and the compressor's frequency" includes: If the frequency of the compressor is not less than the first preset frequency, the suction pressure is not greater than the first preset pressure, and the temperature of the outdoor heat exchanger near the first side of the liquid storage tank is not greater than the first preset temperature, then the bypass valve is opened. If the frequency of the compressor is less than the second preset frequency, the suction pressure is not less than the second preset pressure, and the temperature of the outdoor heat exchanger near the first side of the liquid storage tank is not less than the second preset temperature, then the bypass valve is closed. Wherein, the first preset frequency is greater than the second preset frequency, the first preset pressure is less than the second preset pressure, and the first preset temperature is less than the second preset temperature.

[0017] The beneficial effects of this invention are as follows: The liquid storage tank of this invention includes a tank body and a first connecting pipe; a first interface is provided at the bottom of the tank body; the first end of the first connecting pipe extends from the top of the tank body into the tank body and into the lower half of the tank body, and the first end of the first connecting pipe is bent. When the gas-liquid mixed refrigerant enters from the first connecting pipe, the bent first end is ejected at high speed; the gas-liquid mixture impacts the side wall. During the impact, the liquid refrigerant, due to its high inertia, adheres to the side wall and flows downward, eventually accumulating at the bottom of the tank body; while the gaseous refrigerant, due to its low density and low inertia, rebounds and remains in the upper space of the tank body. After effective separation, the liquid refrigerant at the bottom of the tank body flows out through the first interface of the tank body, ensuring the gas-liquid separation effect.

[0018] Furthermore, when the refrigerant enters through the first inlet at the bottom of the tank, it accumulates in the liquid storage tank. The liquid refrigerant then flows out through the first connecting pipe, while the gaseous refrigerant can be temporarily stored in the liquid storage tank, exchanging heat with the liquid refrigerant there before liquefying. Additionally, the lubricating oil, with its higher density and miscibility with the refrigerant, can flow away through the first connecting pipe, ensuring reliable oil return from the compressor. Moreover, because the first end of the first connecting pipe is bent, the refrigerant entering from the bottom of the liquid storage tank will not directly face the oblique cut of the first connecting pipe. This allows the refrigerant to be temporarily stored in the liquid storage tank before leaving the first connecting pipe, ensuring that gaseous refrigerant does not flow into the first connecting pipe. Attached Figure Description

[0019] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of the structure of the liquid storage tank provided by the present invention; Figure 2 This is a schematic diagram of the air conditioning system provided by the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the air conditioning system provided by the present invention. Figure 2 ; Figure 4 This is a flowchart of the control method for the air conditioning system provided by the present invention.

[0020] List of reference numerals in the attached drawings: 1. Tank body; 2. First connecting pipe; 21. First sub-pipe; 22. Second sub-pipe; 23. Angled cut; 3. Second connecting pipe; 10. Compressor; 20. Oil separator; 30. Four-way valve; 40. Outdoor heat exchanger; 50. Liquid storage tank; 60. Gas-liquid separator; 70. Bypass branch; 71. Bypass valve. Detailed Implementation

[0021] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] To address the problems in the background art of this application, this embodiment discloses a liquid storage tank, an air conditioning system, and a control method thereof.

[0025] Example 1 like Figure 1 As shown in the figure, this embodiment discloses a liquid storage tank 50, wherein the liquid storage tank 50 includes a tank body 1, a first connecting pipe 2, and a second connecting pipe 3.

[0026] Tank 1 is manufactured using a one-piece molding process, specifically using a round tube with tapered ends to form tank 1. The wall thickness of tank 1 is greater than 1mm, and the material is carbon steel to ensure sufficient pressure resistance, thereby ensuring safety during use.

[0027] The tank body 1 has interfaces at both its bottom and top, with the bottom of the tank body 1 serving as the first interface. The first end of the first connecting pipe 2 extends from the top of the tank body 1 into the tank body 1, and into the lower half of the tank body 1. Specifically, the first end of the first connecting pipe 2 is bent. This bending design prevents the fluid entering from the first connecting pipe 2 from directly impacting the outlet at the bottom of the tank body 1, which is beneficial for gas-liquid separation and oil return; the specific flow pattern will be described in detail in later embodiments. It also prevents refrigerant entering from the first interface from directly flowing into the first connecting pipe 2.

[0028] The second connecting pipe 3 is inserted into the bottom interface of the tank 1 and fixed and sealed to the tank 1 to form the first interface.

[0029] The first connecting pipe 2 serves as a channel for the refrigerant to flow between the inside and outside of the tank 1. Specifically, the first end of the first connecting pipe 2 extends into the tank 1 from the top interface, reaching a considerable depth so that its end is located in the lower half of the tank 1; that is, the first end is located at the bottom of the tank 1. More importantly, the first end of the first connecting pipe 2 is not vertically downward, but is bent. The bending angle is greater than 90° and less than 180°, for example, it can be set to 150°, 160°, or 165°. The specific bending angle is determined based on the inner diameter of the top port of the tank 1 and the diameter of the first connecting pipe 2, ensuring that the first connecting pipe 2 can smoothly extend into the tank 1. To allow the first connecting pipe 2 to partially extend into the tank 1, the first connecting pipe 2 includes a first sub-pipe 21 and a second sub-pipe 22. The first sub-pipe 21 is located inside the tank 1, with one end being the aforementioned bent first end. The second sub-pipe 22 is at least partially exposed outside the tank 1 and is used to connect to other components of the air conditioning system. The diameter of the second sub-tube 22 is larger than that of the first sub-tube 21, and the top end of the first sub-tube 21 is inserted into the bottom end of the second sub-tube 22. The diameter of the first sub-tube 21 is smaller, so that the bent part of the first connecting pipe 2 can be smoothly inserted into the tank 1.

[0030] To optimize performance, this embodiment further defines the size and position of the first connecting pipe 2. The distance between the first end (i.e., the bent end) of the first connecting pipe 2 and the bottom wall of the tank 1 is less than 1 / 3 of the overall height h of the tank 1. For example... Figure 1As shown, this distance design ensures that the first end can penetrate deep into the bottom area of ​​the tank 1, effectively absorbing the liquid refrigerant and lubricating oil deposited at the bottom; this will be explained in detail in later embodiments. Regarding the length of the first connecting pipe 2 extending into the tank 1, it should be noted that although it is greater than 2h / 3 in this embodiment, this is not a limitation of the invention. Without departing from the principles of the invention, in other embodiments, if the bottom of the tank 1 is narrow and the volume is small, the length of the first connecting pipe 2 extending into the tank 1 can be reduced; if the bottom cross-sectional area of ​​the tank 1 is large, the first end of the first connecting pipe 2 can be positioned closer to the bottom of the tank. These all do not depart from the basic principles of the invention and will fall within the protection scope of the invention.

[0031] Meanwhile, the minimum distance between the opening at the first end of the first connecting pipe 2 and the side wall of the tank 1 is greater than a first preset value. This first preset value is a constant, preferably 5 mm in this embodiment. This gap can effectively prevent the first connecting pipe 2 from colliding with the side wall of the tank 1 due to vibrations generated by the operation of the air conditioning system, thus avoiding abnormal noise. At the same time, this gap will not be too large, ensuring that the gas-liquid mixture can effectively impact the side wall; the specific flow will be described in detail in subsequent embodiments.

[0032] In addition, such as Figure 1 As shown, the opening direction of the first end of the first connecting pipe 2 is not arbitrary, but preferably set towards the side wall of the tank 1. When the gas-liquid mixture of refrigerant is ejected at high speed from this opening, it will directly impact the inner side wall of the tank 1, achieving a strong gas-liquid separation effect. Furthermore, this opening can be set as a bevel 23, that is, the opening plane is not perpendicular to the axis of the first connecting pipe 2. The bevel 23 increases the effective area of ​​the opening, reduces the fluid outlet velocity, and reduces pressure loss; on the other hand, it can guide the fluid to be ejected towards the side wall at a more optimal angle, enhancing the separation effect.

[0033] Example 2 This embodiment discloses an air conditioning system, specifically a water source multi-split air conditioning system: such as Figure 2 As shown, the system includes a compressor 10, an oil separator 20, a four-way valve 30, an outdoor heat exchanger 40 (preferably a plate heat exchanger), a liquid storage tank 50 as in Embodiment 1, a gas-liquid separator 60, and multiple indoor heat exchangers (not shown in the figure).

[0034] The specific connections are as follows: The exhaust port of compressor 10 is connected to the inlet of oil separator 20, and the outlet of oil separator 20 is connected to the first port of four-way valve 30. The second port of four-way valve 30 is connected to the first side interface of outdoor heat exchanger 40, and the second side interface of outdoor heat exchanger 40 is connected to the second connecting pipe 3 (i.e., the first interface) of liquid storage tank 50. The first connecting pipe 2 (second sub-pipe 22) of liquid storage tank 50 is connected to electronic expansion valve (not shown in the figure), and then connected to indoor heat exchanger. The return gas pipeline of indoor heat exchanger is connected to the third port of four-way valve 30, and the fourth port of four-way valve 30 is connected to the inlet of gas-liquid separator 60; the outlet of gas-liquid separator 60 is connected to the suction port of compressor 10.

[0035] The system also includes multiple temperature and pressure sensors. For example, temperature sensors are installed on both the first and second sides of the outdoor heat exchanger 40; the first side is located near the four-way valve 30, and the second side is located near the liquid storage tank 50; the temperature on the side near the liquid storage tank 50 is designated as Toco, and the temperature on the side near the four-way valve 30 is designated as Toci. Pressure sensors are installed at the suction and discharge ports of the compressor 10, with the suction side pressure designated as the low-pressure Ps and the discharge side pressure designated as the high-pressure Pd.

[0036] Cooling Mode: The four-way valve 30 is reversed, connecting its first and second ports, as well as its third and fourth ports. This allows the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 10 to enter the outdoor heat exchanger 40 after passing through the oil separator 20 and the four-way valve 30. In the outdoor heat exchanger 40, the refrigerant releases heat to the water side (i.e., exchanges heat with water in the plate heat exchanger), condensing into a medium-temperature, high-pressure liquid refrigerant. This liquid refrigerant enters the bottom of the liquid receiver 50, then flows out through the first connecting pipe 2 of the liquid receiver 50, and after being throttled by the electronic expansion valve, enters the indoor heat exchanger to evaporate and absorb heat, achieving a cooling effect. Finally, the refrigerant returns to the compressor 10 via the four-way valve 30 and the gas-liquid separator 60. In this mode, the liquid receiver 50 serves to store excess refrigerant and ensure oil return. Because the liquid storage tank 50 stores excess refrigerant, the liquid level inside the tank 50 is higher than the height of the oblique cut 23. This allows the liquid refrigerant to flow out through the first connecting pipe 2, while the gaseous refrigerant can be temporarily stored in the tank 50, exchanging heat with the liquid refrigerant and then liquefying. The lubricating oil has a higher density and is miscible with the refrigerant, allowing it to flow away through the first connecting pipe 2, ensuring the reliability of the oil return from the compressor 10. Furthermore, because the first end of the first connecting pipe 2 is bent and the oblique cut 23 faces the side wall of the tank 1, the refrigerant entering from the bottom of the tank 50 will not directly face the oblique cut 23 of the first connecting pipe 2. This allows the refrigerant to be temporarily stored in the tank 50 before leaving the first connecting pipe 2, ensuring that the gaseous refrigerant does not flow into the first connecting pipe 2.

[0037] Heating Mode: The four-way valve 30 is switched, connecting the first and third ports, and the second and fourth ports. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 10 directly enters the indoor heat exchanger through the four-way valve 30, releasing heat and condensing into the indoor air. The condensed liquid refrigerant is throttled by the electronic expansion valve into a gas-liquid mixture, and then enters the top of the liquid storage tank 50. After gas-liquid separation is completed in the liquid storage tank 50, the liquid refrigerant flows out from the bottom into the outdoor heat exchanger 40, absorbs heat from the water source and evaporates, becoming gaseous refrigerant, and then returns to the compressor 10 through the four-way valve 30 and the gas-liquid separator 60. In this mode, the gas-liquid separation function of the liquid storage tank 50 is crucial, directly determining the evaporation efficiency of the outdoor heat exchanger 40. Specifically, the high-pressure, medium-temperature liquid refrigerant from the indoor heat exchanger is throttled by the electronic expansion valve into a low-temperature, low-pressure gas-liquid mixture. This gas-liquid mixture enters from the second sub-pipe 22 of the first connecting pipe 2, passes through the first sub-pipe 21, and is ejected at high speed from its first bend. Because the oblique cut 23 faces the side wall of the tank 1, the gas-liquid mixture violently impacts the side wall. During the impact, the liquid refrigerant, due to its greater inertia, adheres to the side wall and flows downwards, eventually accumulating at the bottom of the tank 1; while the gaseous refrigerant, due to its lower density and less inertia, rebounds and remains in the upper space of the tank 1. After effective separation, the liquid refrigerant at the bottom of the tank 1 flows out through the second connecting pipe 3 (first interface) and enters the outdoor heat exchanger 40 (which acts as an evaporator at this time) for evaporation and heat absorption. Since the refrigerant entering the evaporator is mainly liquid, its evaporation and heat absorption capacity is significantly enhanced, thereby improving the heating efficiency.

[0038] Example 3 like Figure 3 As shown, this embodiment discloses an air conditioning system, which has a structure basically the same as the air conditioning system in Embodiment 2. The difference is that the air conditioning system in this embodiment also includes a bypass branch 70. The two ends of the bypass branch 70 are respectively connected to the first connecting pipe 2 (specifically the exposed part of the second sub-pipe 22) and the first interface (i.e., the second connecting pipe 3). A bypass valve 71 is provided on the bypass branch 70. The bypass valve 71 is preferably an electromagnetic on / off valve, but it can also be a valve with controllable opening, such as an electric ball valve.

[0039] In cooling mode, the bypass valve 71 is closed; in heating mode, it is selectively opened according to the system operating status to reduce the flow resistance from the liquid receiver 50 and improve the uniformity of refrigerant distribution entering the outdoor heat exchanger 40. When the bypass valve 71 is open, a portion of the gas-liquid mixed refrigerant bypasses the complex flow path inside the liquid receiver 50 and flows directly to the outdoor heat exchanger 40 through the bypass branch 70, reducing the pressure loss through the liquid receiver 50 and ensuring the amount of refrigerant flowing to the outdoor heat exchanger 40; the other portion still undergoes gas-liquid separation inside the liquid receiver 50. The two fluids mix at the connection point between the bypass branch 70 and the first interface, increasing the turbulence of the fluid and helping to improve the uniformity of liquid distribution between the flow paths of the outdoor heat exchanger 40 (as an evaporator), thereby improving heat exchange efficiency and energy efficiency. Moreover, Specifically, such as Figure 4 As shown, in heating mode, the control method for controlling the opening degree of bypass valve 71 includes the following main steps: S1. Obtain the temperature of the outdoor heat exchanger 40 near the liquid storage tank 50, the suction pressure of the compressor 10, and the frequency of the compressor 10; S2. Determine the opening degree of the bypass valve 71 based on the temperature of the outdoor heat exchanger 40 near the liquid storage tank 50, the suction pressure of the compressor 10, and the frequency of the compressor 10.

[0040] Specifically, step S2, "determining the opening degree of bypass valve 71 based on the temperature of the outdoor heat exchanger 40 near the liquid storage tank 50, the suction pressure of compressor 10, and the frequency of compressor 10," includes: If the frequency F of compressor 10 is not less than the first preset frequency F1, the suction pressure Ps is not greater than the first preset pressure Ps1, and the temperature Toco of the outdoor heat exchanger 40 near the first side of the liquid storage tank 50 is not greater than the first preset temperature T1, then the bypass valve 71 is opened. In heating mode, the bypass valve 71 is normally closed; it is only opened when the above conditions are met.

[0041] Among them, the first preset frequency F1 = 60% of the maximum frequency; the first preset temperature T1 = 18℃; the first preset pressure Ps1 = 13Bar; at this time, the frequency is relatively high, but the pressure and temperature are relatively low. That is, the opening condition is high frequency, low pressure and low temperature opening.

[0042] When compressor 10 operates at high frequency, the system requires a large amount of refrigerant circulation. If the suction pressure is low (e.g., below 13 Bar) and the outlet temperature of outdoor heat exchanger 40 is low (e.g., below 18°C), it indicates insufficient evaporation pressure, limited refrigerant flow, and pressure loss in receiver 50 becoming a system bottleneck. Opening bypass valve 71 at this time can significantly reduce flow resistance, increase the refrigerant flow into outdoor heat exchanger 40, and improve evaporation pressure, thereby enhancing heating capacity and energy efficiency.

[0043] Specifically, step S2, "determining the opening degree of bypass valve 71 based on the temperature of the outdoor heat exchanger 40 near the liquid storage tank 50, the suction pressure of compressor 10, and the frequency of compressor 10," further includes: If the frequency F of compressor 10 is less than the second preset frequency F2, the suction pressure Ps is not less than the second preset pressure Ps2, and the temperature Toco of outdoor heat exchanger 40 near the first side of liquid storage tank 50 is not less than the second preset temperature T2, then the bypass valve 71 is closed; when the bypass valve 71 is open, the expansion valve is closed after the above conditions are met.

[0044] Among them, the first preset frequency is greater than the second preset frequency, the first preset pressure is less than the second preset pressure, and the first preset temperature is less than the second preset temperature.

[0045] The second preset frequency F2 = 55% of the maximum frequency; the second preset pressure Ps2 = 16 Bar; the second preset temperature T2 = 25℃; at this time, the compressor 10 has a low frequency, but the suction pressure and temperature are relatively high. Therefore, the shutdown condition is low frequency, high pressure and high temperature shutdown.

[0046] When compressor 10 operates at low frequency, the system's refrigerant circulation demand is relatively small. If the suction pressure is high at this time (e.g., above 16 Bar) and the outlet temperature of outdoor heat exchanger 40 is high (e.g., above 25°C), it indicates sufficient evaporation, and there may even be low return gas superheat, posing a risk of liquid slugging. If the amount of refrigerant remaining in outdoor heat exchanger 40 is increased through bypass branch 70 at this time, it may lead to insufficient heat exchange in outdoor heat exchanger 40. Closing bypass valve 71 reduces the amount of refrigerant flowing to outdoor heat exchanger 40, ensuring the heat exchange efficiency of outdoor heat exchanger 40, thereby reducing the suction pressure and avoiding the risk of liquid slugging. After closing bypass valve 71, all refrigerant undergoes normal gas-liquid separation through receiver 50 to ensure basic system circulation.

[0047] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A liquid storage tank, characterized in that, The storage tank (50) includes: The tank (1) has a first interface at its bottom; The first connecting pipe (2) has its first end extending from the top of the tank (1) into the tank (1) and into the lower half of the tank (1), and the first end of the first connecting pipe (2) is bent.

2. The liquid storage tank according to claim 1, characterized in that, The distance between the first connecting pipe (2) and the bottom wall of the tank (1) is less than 1 / 3h; where h is the height of the tank (1).

3. The liquid storage tank according to claim 1, characterized in that, The minimum distance between the opening at the first end of the first connecting pipe (2) and the side wall of the tank (1) is greater than a first preset value; wherein, the first preset value is a constant.

4. The liquid storage tank according to claim 1, characterized in that, The opening at the first end of the first connecting pipe (2) is disposed facing the side wall of the tank body (1); and / or The opening at the first end of the first connecting pipe (2) is a bevel (23).

5. The liquid storage tank according to claim 1, characterized in that, The first connecting pipe (2) includes a first sub-pipe (21) and a second sub-pipe (22), the first sub-pipe (21) extending into one end of the second sub-pipe (22); the first sub-pipe (21) is located inside the tank (1), and the second sub-pipe (22) is at least partially exposed outside the tank (1).

6. The liquid storage tank according to claim 1, characterized in that, It also includes a second connecting pipe (3), which is connected to the bottom end of the tank (1) to form a first interface at the bottom of the tank (1); and / or The first connecting pipe (2) is welded to the tank body (1); and / or The second connecting pipe (3) is welded to the tank body (1); and / or The tank body (1) is integrally formed.

7. An air conditioning system, characterized in that, The air conditioning system includes: Outdoor heat exchanger (40); Indoor heat exchanger; The liquid storage tank (50) as described in any one of claims 1-6, wherein the first interface is connected to the outdoor heat exchanger (40); and the first end of the first connecting pipe (2) is connected to the indoor heat exchanger.

8. The air conditioning system according to claim 7, characterized in that, It also includes a bypass branch (70), the two ends of which are connected to the first connecting pipe (2) and the first interface, respectively; a bypass valve (71) is provided on the bypass branch (70).

9. A control method for an air conditioning system as described in claim 8, characterized in that, The control method includes the following steps: In heating mode, the opening degree of the bypass valve (71) is determined based on the temperature of the outdoor heat exchanger (40) near the liquid storage tank (50), the suction pressure of the compressor (10), and the frequency of the compressor (10).

10. The control method according to claim 9, characterized in that, "Determining the opening degree of the bypass valve (71) based on the temperature of the outdoor heat exchanger (40) near the liquid storage tank (50), the suction pressure of the compressor (10), and the frequency of the compressor (10) includes: If the frequency of the compressor (10) is not less than the first preset frequency, the suction pressure is not greater than the first preset pressure, and the temperature of the outdoor heat exchanger (40) on the first side near the liquid storage tank (50) is not greater than the first preset temperature, then the bypass valve (71) is opened. If the frequency of the compressor (10) is less than the second preset frequency, the suction pressure is not less than the second preset pressure, and the temperature of the outdoor heat exchanger (40) on the first side near the liquid storage tank (50) is not less than the second preset temperature, then the bypass valve (71) is closed. Wherein, the first preset frequency is greater than the second preset frequency, the first preset pressure is less than the second preset pressure, and the first preset temperature is less than the second preset temperature.

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