Air conditioning system and control method

Abstract

Heat exchange pipelines of a first heat exchanger are divided into a first heat exchange pipe set close to a heat exchange fan and a second heat exchange pipe set away from the heat exchange fan, one side of the first heat exchange pipe set is connected with a first throttling valve, and the other side of the first heat exchange pipe set is connected with the C end of a four-way valve; one side of the second heat exchange tube set is connected with one side of the first heat exchange tube set, and the other side of the second heat exchange tube set is connected with the E end of the four-way valve through a bypass pipeline capable of being opened and closed. During heating operation, the bypass pipeline can be communicated, high-temperature and high-pressure refrigerant gas exhausted by the compressor can partially enter the second heat exchange pipe set (namely, the fin area prone to freezing) through the bypass pipeline, the ice layer is rapidly melted through heat of the high-temperature gas, the defrosting function is achieved, and therefore the operation time of the heating mode is prolonged, and the heating efficiency is improved. Defrosting cleanness of the fins is guaranteed, refrigeration oil diluted by liquid refrigerants is reduced, and therefore the service life of the compressor is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and particularly to an air conditioning system and a control method thereof. Background Art

[0002] In the after-sales application, there are problems of incomplete defrosting and ice accumulation at the bottom of the fins in the unit equipment. Such problems have a significant negative impact on the product reliability and brand reputation. Through in-factory simulation test analysis, it is found that during the switching process from the heating mode to the defrosting mode, there is a phenomenon of heat exchange efficiency attenuation in the flow path area at the end of the fins: specifically, the frost layer in the upper area of the fins melts earlier than that in the bottom area. When the defrosting water flows downward under the action of gravity to the bottom of the fins, since the temperature of the bottom flow path has not reached the threshold required for the ice phase change, the liquid water undergoes secondary condensation on the low-temperature surface. Due to the preset time limit in the defrosting process, when the temperature of the bottom area of the fins rises to the threshold required for defrosting, more than 50% of the defrosting cycle time has been consumed, and the remaining time is not enough to complete the complete phase change process of the ice accumulation at the bottom. Through the verification of the multi-cycle cumulative effect, the remaining ice layer that has not completely melted forms an ice blockage structure at the bottom of the fins, which may ultimately lead to the risk of copper pipe stress concentration and frost heaving rupture. Summary of the Invention

[0003] In order to solve the technical problem of low defrosting efficiency at the bottom of the heat exchanger in the above-mentioned prior art, the present invention provides an air conditioning system and a control method thereof.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention provides an air conditioning system, including a compressor, a first heat exchanger, a second heat exchanger, a first throttle valve, and a four-way valve. The exhaust end and the suction end of the compressor are respectively connected to the D end and the S end of the four-way valve through pipelines. The C end of the four-way valve is connected to the first heat exchanger, the first throttle valve, the second heat exchanger, and the E end of the four-way valve in sequence through pipelines.

[0006] The heat exchange pipelines of the first heat exchanger are divided into a first heat exchange tube group close to the heat exchange fan and a second heat exchange tube group far from the heat exchange fan. One side of the first heat exchange tube group is connected to the first throttle valve, and the other side is connected to the C end of the four-way valve. One side of the second heat exchange tube group is connected to one side of the first heat exchange tube group, and the other side is connected to the E end of the four-way valve through an openable and breakable bypass pipeline.

[0007] Further, a second throttle valve is also provided on the side where the second heat exchange tube group is connected to the first heat exchange tube group.

[0008] Furthermore, the heat exchange fan is arranged on the top of the first heat exchanger, and the second heat exchange tube group is at least one layer of heat exchange pipelines at the bottom of the first heat exchanger.

[0009] Furthermore, the heat exchange pipes of the second heat exchange tube group are arranged in a staggered manner with the heat exchange pipes at the bottom of the first heat exchange tube group.

[0010] The present invention also provides a control method for an air conditioning system, using the above air conditioning system; including the steps:

[0011] When the air conditioner operates in the heating mode, it is judged whether the temperature difference △Tc between the first heat exchanger and the ambient temperature is greater than the first set value A;

[0012] If so, the bypass pipe is connected to make the pipes of the second heat exchange tube group connected; if not, the bypass pipe is closed or remains in the closed state.

[0013] Furthermore, it further includes the step: after the bypass pipe is connected, when the temperature difference △Tc between the first heat exchanger and the ambient temperature is less than or equal to the first set value A, the bypass pipe is closed.

[0014] When the air conditioner operates in the cooling mode, it is judged whether the temperature difference △Te between the first heat exchanger and the ambient temperature is less than the second set value B;

[0015] If so, the bypass pipe is connected to make the pipes of the second heat exchange tube group connected; if not, the bypass pipe is closed or remains in the closed state.

[0016] Furthermore, it further includes the step: after the bypass pipe is connected, when the temperature difference △Te between the first heat exchanger and the ambient temperature is greater than or equal to the second set value B, the bypass pipe is closed.

[0017] Furthermore, after the bypass pipe is connected, the opening degree of the second throttle valve is controlled to make the temperature of the refrigerant after throttling in the second heat exchange tube group consistent with the temperature on one side of the first heat exchange tube group.

[0018] The present invention also provides a computer-readable storage medium for storing a computer program, and when the computer program runs, it executes the above control method.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] During heating operation, the bypass pipe can be connected, so that the high-temperature and high-pressure refrigerant gas discharged by the compressor can partially enter the second heat exchange tube group (i.e., the fin area prone to icing) through the bypass pipe, and the heat of the high-temperature gas is used to quickly melt the ice layer, realizing the defrosting function, thereby extending the operation time of the heating mode, ensuring that the fins are defrosted cleanly, reducing the dilution of the liquid refrigerant to the refrigerating oil, and thus improving the service life of the compressor. During cooling operation, after the refrigerant passes through the first throttle valve and throttles to a low-temperature and low-pressure state, the bypass pipe is also connected at this time, and part of the low-temperature refrigerant directly enters the second heat exchange tube group, further reducing the fin temperature in this area and improving the overall heat exchange efficiency. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 is the system diagram of the embodiment of the present invention;

[0023] Figure 2 is the system diagram of the heating mode in the embodiment of the present invention;

[0024] Figure 3 is the system diagram of the cooling mode in the embodiment of the present invention;

[0025] Figure 4 is the front view of the first heat exchanger in the embodiment of the present invention;

[0026] Figure 5 is the side view of the first heat exchanger in the embodiment of the present invention;

[0027] Figure 6 is the top view of the first heat exchanger in the embodiment of the present invention;

[0028] Figure 7 is the flowchart in the embodiment of the present invention;

[0029] 1. Compressor;

[0030] 2. First heat exchanger;

[0031] 3. Heat exchange fan;

[0032] 4. Second heat exchanger;

[0033] 5. Four-way valve;

[0034] 6. Gas-liquid separator;

[0035] 71. First throttle valve; 72. Second throttle valve;

[0036] 8. Bypass pipeline; 81. Solenoid valve;

[0037] 9. Filter. Detailed implementation manners

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the following further details the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] The principles and structure of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0040] In the prior art, during the switching process from the heating mode to the defrosting mode, there is a phenomenon of attenuation of heat exchange efficiency in the fin end flow path area: specifically, the frost layer in the upper area of the fin melts earlier than that in the bottom area. When the defrosting water flows downward under the action of gravity to the bottom of the fin, since the temperature of the bottom flow path has not reached the threshold required for the phase change of the ice layer, the liquid water undergoes secondary condensation on the low-temperature surface. Since the defrosting process has a preset time limit, when the temperature of the bottom area of the fin rises to the threshold required for defrosting, more than 50% of the defrosting cycle time has been consumed, and the remaining time is not enough to complete the complete phase change process of the ice accumulation at the bottom.

[0041] In response to this, as Figures 1 to 3 shown, the present invention proposes an air-conditioning system, which includes a compressor 1, a first heat exchanger 2 (fin heat exchanger), a second heat exchanger 4 (specifically, it can be a water-side heat exchanger), a first throttle valve 71, and a four-way valve 5. Among them: the exhaust end and the suction end of the compressor 1 are respectively connected to the D end and the S end of the four-way valve 5 through pipelines, and the C end of the four-way valve 5 is connected to the first heat exchanger 2, the first throttle valve 71, the second heat exchanger 4, and the E end of the four-way valve 5 in sequence through pipelines.

[0042] The heat exchange pipes of the first heat exchanger 2 are divided into a first heat exchange pipe group 21 close to the heat exchange fan 3 and a second heat exchange pipe group 22 far from the heat exchange fan 3. One side of the first heat exchange pipe group is connected to the first throttle valve 71, and the other side is connected to the C end of the four-way valve 5; one side of the second heat exchange pipe group is connected to the pipeline between the first throttle valve 71 and the first heat exchange pipe group, and the other side is directly connected to the E end of the four-way valve 5 through a bypass pipeline 8, and a solenoid valve 81 is provided on the bypass pipeline 8 for opening and closing the bypass pipeline 8.

[0043] During the heating operation, when the fins are frozen due to the low ambient temperature, the bypass pipeline can be connected, so that part of the high-temperature and high-pressure refrigerant gas discharged from the compressor can enter the second heat exchange pipe group (i.e., the fin area prone to icing) through the bypass pipeline, and the ice layer can be quickly melted by using the heat of the high-temperature gas, realizing the defrosting function, thereby prolonging the operation time of the heating mode. During the cooling operation, the refrigerant becomes a low-temperature and low-pressure state after throttling through the first throttle valve. At this time, the bypass pipeline is also connected, and part of the low-temperature refrigerant directly enters the second heat exchange pipe group, further reducing the fin temperature in this area and improving the overall heat exchange efficiency.

[0044] By dividing the heat exchange pipe group of the first heat exchanger into two groups close to and far from the heat exchange fan, and arranging a bypass pipeline between the second heat exchange pipe group and the E end of the four-way valve, the system can dynamically adjust the refrigerant flow path under different operating modes. During heating, defrosting is realized by bypassing high-temperature refrigerant; during cooling, heat exchange is enhanced by bypassing low-temperature refrigerant, reducing energy loss.

[0045] In a specific embodiment, Figure 3 , 4 As shown, the air conditioning system is provided with a second throttle valve 72 in the connecting pipeline between the second heat exchange tube group 22 and the first heat exchange tube group 21. The valve body independently adjusts the flow rate and pressure of the refrigerant in the second heat exchange tube group so that the temperature of the refrigerant after throttling is balanced with the temperature of the refrigerant on the corresponding side of the first heat exchange tube group.

[0046] In heating mode, when the bypass pipe is opened, the high-temperature refrigerant flows through the second heat exchange tube group, and the second throttle valve can adjust the throttling area to ensure that its temperature drop rate matches that of the refrigerant in the first heat exchange tube group; in cooling mode, when the low-temperature refrigerant is diverted to the second heat exchange tube group, the second throttle valve adjusts the throttling area to avoid overcooling caused by excessive accumulation of cold, so that the two refrigerants reach temperature equilibrium before merging.

[0047] This design solves the problems of low refrigerant mixing efficiency and high flow resistance caused by temperature differences in traditional systems by forcibly balancing the temperatures of the two refrigerants. Refrigerants with the same temperature can enter the subsequent pipelines more stably after merging, reducing heat transfer attenuation caused by phase differences and reducing energy loss in the refrigerant circulation system.

[0048] Specifically, the heat exchange fan of the outdoor unit is arranged on the top of the first heat exchanger, and its air outlet direction is upward, forming an air circulation path from bottom to top. At least one layer of heat exchange pipes in the bottom area of ​​the first heat exchanger constitutes a second heat exchange pipe group, and part of the heat exchange pipes at the bottom of the first heat exchange pipe group may overlap with the heat exchange pipes of the second heat exchange pipe group, or may not overlap.

[0049] In a preferred embodiment, Figures 4 to 6 As shown, part of the heat exchange pipes at the bottom of the first heat exchange tube group 21 overlap and intersect with the heat exchange pipes of the second heat exchange tube group 22 to improve the heat exchange efficiency at the bottom of the heat exchanger.

[0050] The top installation position of the heat exchange fan allows the airflow to flow upward from the bottom of the heat exchanger, and preferentially passes through the second heat exchange area (i.e., the bottom pipe that is prone to frost or condensation): in the heating mode, when the high-temperature refrigerant enters the second heat exchange tube group through the bypass pipe, the fins of the bottom pipe that are prone to frost can be heated and defrosted, thereby improving the defrosting efficiency and extending the heating time. In the cooling mode, after the low-temperature refrigerant releases coldness in the second heat exchange area, the rising airflow first passes through the refrigerant to cool down before reaching the first heat exchange tube group, thereby improving the actual heat exchange effect of the first heat exchanger.

[0051] In a specific embodiment, a filter 9 is arranged on the connecting pipeline of the first heat exchanger 2 and the second heat exchanger 4. Specifically, a filter 9 can be provided between the first throttle valve 71 and the first heat exchanger 2, a filter 9 can be provided between the first throttle valve 71 and the second heat exchanger 4, and a filter 9 can be provided between the second heat exchanger 4 and the E end of the four-way valve 5. The filter can intercept impurity particles and wear debris in the refrigerant, ensuring that the refrigerant remains clean during the pipeline circulation process.

[0052] Preferably, the filter adopts a replaceable filter element structure, and its installation position is on the main pipeline where the refrigerant flows from the first heat exchanger to the second heat exchanger, so as to reduce the additional influence on the flow resistance of the refrigerant. During the operation of the system, the filter continuously intercepts impurities such as metal debris and oxides, preventing them from entering the inside of the heat exchange tube group to block the microchannels or damage the valve seals.

[0053] In addition, it should be noted that two main pipes are respectively converged on both sides of the first heat exchange tube group, namely the total liquid pipe and the total gas pipe. During refrigeration, the refrigerant flows from the total gas pipe → the total liquid pipe; during heating, due to the switching of the four-way valve, the flow direction of the flow path becomes the total liquid pipe → the total gas pipe. Specifically, a total liquid pipe inlet is provided corresponding to the first heat exchange tube group.

[0054] The convergence form of the second heat exchange tube group is the same as that of the first heat exchange tube group, specifically the branch liquid pipe and the branch gas pipe.

[0055] In a specific embodiment, a gas-liquid separator is also provided on the suction side of the compressor to reduce energy loss and pressure fluctuation.

[0056] As Figure 7 shown, the present invention also proposes a control method for an air conditioning system; specifically including:

[0057] During the heating operation, by continuously monitoring the temperature difference △Tc between the first heat exchanger (specifically, the temperature of the total liquid pipe can be detected, or the fin temperature, or the conventional defrost detection position, etc.) and the environment, and comparing it with the preset threshold A, this is used as the determination basis for opening and closing the bypass pipeline.

[0058] The specific execution process is as follows: The system continuously collects the real-time data of the temperature of the first heat exchanger and the environment temperature, and calculates the temperature difference △Tc between the two. When this temperature difference exceeds the preset value A, it indicates that there may be a risk of frosting on the heat transfer surface or local subcooling phenomenon of the first heat exchanger due to low ambient temperature or high load. At this time, the control system immediately starts the bypass pipeline, so that the high-temperature refrigerant is diverted to the second heat exchange tube group area. The high-temperature refrigerant releases heat in the second heat exchange area, directly increasing the fin surface temperature in this area, melting the formed frost layer or inhibiting the formation of new frost.

[0059] If it is detected that △Tc does not exceed the threshold A, the bypass pipeline remains closed, and the refrigerant runs along the main circulation path to maintain the basic heating efficiency. This segmented control strategy can accurately match the requirements of different working conditions: in the low-temperature and high-load scenario, the opening of the bypass pipeline avoids the decrease in heat exchange efficiency caused by frosting on the surface of the heat exchanger through heat redistribution; while in a mild environment, unnecessary refrigerant diversion is avoided to reduce energy loss.

[0060] This method realizes preventive management of heat exchanger frosting by directly associating temperature difference monitoring with bypass control. The area of the second heat exchange tube group defrosts by continuously receiving the heat of the high-temperature refrigerant; at the same time, the on-demand opening and closing of the bypass pipeline can dynamically balance the refrigerant distribution between the main heat exchange area and the area of the second heat exchange tube group, ensuring the optimal combination of overall heating capacity and energy efficiency. Compared with the traditional timed defrosting method, this method reduces the ineffective heating energy consumption and avoids the room temperature fluctuation caused by excessive defrosting, improving the system operation stability and user comfort.

[0061] In a further embodiment, during heating, when it is monitored that the temperature difference △Tc between the first heat exchanger and the ambient temperature returns to be less than or equal to the set threshold A, the system will close the solenoid valve and the second throttle valve associated with the bypass pipeline.

[0062] When the ambient temperature rises or the heating load decreases, causing △Tc to return to the normal range, the control system determines that the frosting risk of the first heat exchanger is lifted, then cuts off the power supply of the solenoid valve and closes the second throttle valve. Terminate the refrigerant diversion path to the second heat exchange tube group, so that the refrigerant flow is re-concentrated in the main heat exchange area. The air-conditioning system realizes the dynamic balance of heat distribution and energy consumption in the heating mode, ensuring the anti-frosting ability in extreme environments and avoiding resource waste, ultimately improving the overall energy efficiency ratio and the service life of the equipment.

[0063] In a specific embodiment, the control method of the air-conditioning system further includes the steps:

[0064] During refrigeration operation, by monitoring the temperature difference △Te between the first heat exchanger and the ambient temperature and using the set threshold B as the trigger condition, the opening and closing of the bypass pipeline and the dynamic adjustment of the heat dissipation capacity are realized.

[0065] The specific execution process is as follows: when it is detected that △Te is lower than the set value B, it indicates that the ambient temperature is relatively high and the heat exchange load of the current fin is relatively high. When it exceeds the load of the fin, the burden on the fan will be increased synchronously, which will increase the electric power of the fan and the power consumption of the whole machine will increase sharply. At this time, the control system connects the bypass pipeline to divert part of the low-temperature refrigerant to the second heat exchange tube group, reducing the temperature of the fin, and thus the power consumption of the whole machine will also be reduced. If △Te is not lower than the threshold B, the bypass pipeline is closed, and the refrigerant circulates along the main path to maintain efficient refrigeration. If △Te is not lower than the threshold B, the bypass pipeline is closed, and the refrigerant runs along the main path to maintain an efficient refrigeration cycle.

[0066] This control achieves heat dissipation redundancy by diverting low-temperature refrigerant: in high-temperature environmental conditions, the second heat exchange area serves as a supplementary heat dissipation module, using low-temperature refrigerant to preferentially exchange heat with the environment, reducing the load on the first heat exchanger. Additionally, it can prevent the abnormal increase in the compressor discharge temperature caused by refrigerant overheating.

[0067] In a further embodiment, when it is monitored that the temperature difference △Te between the first heat exchanger and the ambient temperature rises back to be greater than or equal to the set threshold B, the system will close the solenoid valve and the second throttle valve associated with the bypass pipe.

[0068] During specific implementation, when the ambient temperature drops or the refrigeration load decreases, causing △Te to reach or exceed the threshold B again, the control system determines that the heat dissipation capacity of the main heat exchange area has been restored, and then cuts off the power supply of the solenoid valve and closes the second throttle valve. The diversion path of the low-temperature refrigerant to the second heat exchange tube group is terminated, causing the refrigerant flow rate to be re-concentrated in the main heat exchange area. That is, when the ambient temperature returns to a reasonable range, the diversion operation of the low-temperature refrigerant is stopped in a timely manner, reducing the additional pressure drop loss caused by the bypass path, and at the same time ensuring that the refrigerant flow rate in the main heat exchange area is restored to the optimal state, maintaining an efficient condensation process.

[0069] In a specific embodiment, after the bypass pipe is opened, the temperature of the refrigerant after throttling in the second heat exchange tube group is synchronized with the temperature on the side of the first throttle valve connected to the first heat exchange tube group by dynamically adjusting the opening degree of the second throttle valve.

[0070] During specific implementation, the system real-time collects the temperature at the liquid outlet side of the second heat exchange tube group (i.e., the branch liquid pipe) and the temperature of the total liquid pipe of the first heat exchange tube group (the side connected to the first throttle valve), and based on the temperature difference △Tevb, feedback adjusts the opening degree of the second throttle valve. The control system increases the opening degree of the second throttle valve to increase the refrigerant flow rate, and vice versa to reduce the opening degree to limit the refrigerant flow rate, ultimately making the two temperatures tend to be the same. This closed-loop control mechanism ensures the balanced heat exchange efficiency of the refrigerant in the diversion path, avoiding local overcooling or overheating phenomena caused by temperature differences.

[0071] Through temperature consistency control, the system achieves collaborative heat dissipation in multiple heat exchange areas: eliminating the temperature difference between the first heat exchange tube group and the second heat exchange tube group for the refrigerant can reduce the uneven phase change of the refrigerant or local pressure fluctuations caused by the temperature difference, and reduce the risk of abnormal vibration of the compressor caused by refrigerant overheating or overcooling.

[0072] The present invention also proposes a computer-readable storage medium for storing a computer program, and when the computer program runs, it executes the above control method.

[0073] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0074] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof in subsequent drawings is not necessary.

[0075] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the outline of each component itself.

[0076] In addition, it should be noted that the use of words such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without additional statements, the above words have no special meanings, and thus should not be construed as limiting the protection scope of the present invention.

[0077] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An air conditioning system, comprising a compressor, a first heat exchanger, a second heat exchanger, a first throttle valve and a four-way valve. The exhaust end and the suction end of the compressor are respectively connected to the D end and the S end of the four-way valve through pipelines. The C end of the four-way valve is connected to the E end of the four-way valve through the first heat exchanger, the first throttle valve, the second heat exchanger and a pipeline in sequence. It is characterized in that the heat exchange pipelines of the first heat exchanger are divided into a first heat exchange tube group close to the heat exchange fan and a second heat exchange tube group far from the heat exchange fan. One side of the first heat exchange tube group is connected to the first throttle valve and the other side is connected to the C end of the four-way valve. One side of the second heat exchange tube group is connected to one side of the first heat exchange tube group, and the other side is connected to the E end of the four-way valve through an openable and breakable bypass pipeline; when the air conditioner operates in the heating mode, it is judged whether the temperature difference △Tc between the first heat exchanger and the ambient temperature is greater than a first set value A; if so, the bypass pipeline is connected to make the pipelines of the second heat exchange tube group communicate; if not, the bypass pipeline is closed or remains in the closed state.

2. The air conditioning system according to claim 1, characterized in that, A second throttle valve is further provided on one side of the second heat exchange tube group connected to the first heat exchange tube group.

3. The air-conditioning system according to claim 1, wherein The heat exchange fan is arranged on the top of the first heat exchanger, and the second heat exchange tube group is at least one layer of heat exchange pipelines arranged at the bottom of the first heat exchanger.

4. The air conditioning system according to claim 3, characterized in that, The heat exchange pipelines of the second heat exchange tube group are arranged in a staggered manner with the heat exchange pipelines at the bottom of the first heat exchange tube group.

5. A control method for an air conditioning system, characterized in that, Using the air conditioning system according to any one of claims 1 to 4; including steps: when the air conditioner operates in the cooling mode, it is judged whether the temperature difference △Te between the first heat exchanger and the ambient temperature is less than a second set value B; if so, the bypass pipeline is connected to make the pipelines of the second heat exchange tube group communicate; if not, the bypass pipeline is closed or remains in the closed state.

6. The control method of the air conditioning system according to claim 5 further includes the step: after the bypass pipeline is connected in the heating mode, when the temperature difference △Tc between the first heat exchanger and the ambient temperature is less than or equal to the first set value A, the bypass pipeline is closed.

7. The control method of the air conditioning system according to claim 5 further includes the step: after the bypass pipeline is connected in the cooling mode, when the temperature difference △Te between the first heat exchanger and the ambient temperature is greater than or equal to the second set value B, the bypass pipeline is closed.

8. In the control method of the air conditioning system according to claim 5, when the bypass pipeline is opened, the opening degree of the second throttle valve is controlled to make the temperature after throttling of the second heat exchange tube group consistent with the temperature on one side of the first heat exchange tube group.

9. A computer-readable storage medium for storing a computer program, and when the computer program runs, it executes the control method according to any one of claims 5 to 8.

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