Outdoor heat exchanger, air conditioning system and defrosting delay control method

Abstract

The invention relates to the technical field of air conditioners, in particular to an outdoor heat exchanger, an air conditioning system and a defrosting delay control method. The problems that an existing large-cooling-capacity air conditioning unit is frequent in defrosting, and the heating effect is affected are solved. In order to achieve the purpose, the outdoor heat exchanger, the air conditioning system and the delayed defrosting control method are provided, the outdoor heat exchanger comprises heat exchange flow paths and supercooling flow paths, heat exchange can be achieved between the heat exchange flow paths and the supercooling flow paths, and the number of the heat exchange flow paths and the number of the supercooling flow paths are both multiple; the multiple heat exchange flow paths are arranged in parallel, two confluence ports are formed in the two ends of each heat exchange flow path, the multiple supercooling flow paths are arranged in parallel, and two confluence ports are formed in the two ends of each supercooling flow path. According to the scheme, during heating, the multiple supercooling pipelines can melt frost formed on the surfaces of the multiple heat exchange flow paths, and then the effect of delaying defrosting is achieved.

Description

Technical Field

[0001] The present invention and the technical field of air conditioning particularly relate to an outdoor heat exchanger, an air conditioning system and a delayed defrost control method. Background Art

[0002] High-cooling-capacity air conditioners offer advantages such as high load handling capacity and high integration, making them a growing research focus for major manufacturers. During winter heating operation, condensers can frost. This increases the heat exchange resistance between the refrigerant and the environment, reducing the unit's heating efficiency. Therefore, when frost reaches a certain level, the unit enters a defrost process.

[0003] High-capacity air conditioners frost faster than conventional units, leading to more rapid capacity degradation. Furthermore, the four-way valve reversing defrost causes more frequent compressor frequency increases and decreases, making the defrost cycle longer. Furthermore, during the defrost process, the indoor unit stops blowing warm air, which can reduce the user's indoor heating performance. The longer defrost time of high-capacity air conditioners significantly impacts heating performance.

[0004] Accordingly, this field requires a new technical solution to solve the above problems. Summary of the Invention

[0005] In order to solve at least one of the above problems in the prior art, that is, to solve the problem of frequent defrosting and affecting the heating effect of the existing large-capacity air-conditioning units, the present application provides an outdoor heat exchanger, wherein the outdoor heat exchanger includes a heat exchange flow path and a subcooling flow path, the heat exchange flow path and the subcooling flow path are capable of exchanging heat, and the heat exchange flow path and the subcooling flow path are each provided with a plurality of heat exchange flow paths, the plurality of heat exchange flow paths are provided in parallel, and the two ends of the plurality of heat exchange flow paths have two confluence ports, and the plurality of subcooling flow paths are provided in parallel, and the two ends of the plurality of subcooling flow paths have two confluence ports;

[0006] The two confluence ports of the plurality of heat exchange paths are respectively used to connect to the compressor and the throttling device, and the two confluence ports of the plurality of subcooling paths are respectively used to connect to the indoor heat exchanger and the throttling device.

[0007] When the above technical solution is adopted, during heating, multiple subcooling pipes can melt frost formed on the surfaces of multiple heat exchange flow paths, thereby achieving the effect of delayed defrosting.

[0008] In the preferred technical solution of the above-mentioned outdoor heat exchanger, the number of the heat exchange flow paths is equal to the number of the subcooling flow paths, and the heat exchange flow paths correspond to the subcooling flow paths one by one, and each heat exchange flow path is arranged adjacent to the corresponding subcooling flow path.

[0009] In a preferred technical solution of the above-mentioned outdoor heat exchanger, the length of the heat exchange flow path is greater than the length of the subcooling flow path.

[0010] In the preferred technical solution of the outdoor heat exchanger, the outdoor heat exchanger further includes a plurality of defrost sensors, the number of the heat exchange flow paths is equal to the number of the defrost sensors, and each of the heat exchange flow paths is provided with one defrost sensor; and / or

[0011] The outdoor heat exchanger further includes a plurality of control valves. The number of the heat exchange flow paths is equal to the number of the control valves. One control valve is provided on each heat exchange flow path so that each heat exchange flow path can be opened and closed independently.

[0012] The present application also provides an air-conditioning system, which includes the outdoor heat exchanger as described in any one of the above items.

[0013] When using the above-mentioned outdoor heat exchanger, multiple heat exchange paths in the outdoor heat exchanger can exchange heat with multiple subcooling pipes. When the air-conditioning system is in heating mode, multiple subcooling pipes can melt the frost on the surfaces of multiple heat exchange paths, making the outdoor heat exchanger frost slower, thereby achieving the effect of delayed defrosting.

[0014] The present application also provides a delayed defrost control method for an air conditioning system, wherein the air conditioning system includes an outdoor heat exchanger and multiple indoor heat exchangers, wherein the outdoor heat exchanger includes multiple heat exchange flow paths arranged in parallel, and each of the heat exchange flow paths can be independently switched on and off;

[0015] The delayed defrost control method comprises:

[0016] When the air conditioning system is in heating mode, obtaining the load of the indoor unit;

[0017] determining the number of heat exchange paths to be used based on the internal machine load;

[0018] Based on the usage quantity, controlling the on / off state of each of the heat exchange flow paths so that a corresponding number of the heat exchange flow paths are in an on state;

[0019] There is a corresponding relationship between the internal machine load and the number of heat exchange paths in use.

[0020] When the above technical solution is adopted, it is beneficial to ensure that the outdoor heat exchanger can be evenly frosted while ensuring the heating capacity of the air-conditioning system, so that the outdoor heat exchanger can be fully utilized, thereby achieving the effect of delayed defrosting.

[0021] In the preferred technical solution of the above-mentioned delayed defrost control method, the controlling of the on / off state of each of the heat exchange flow paths based on the usage quantity further includes:

[0022] Based on the usage quantity and the frosting condition of each of the heat exchange flow paths, the on-off state of each of the heat exchange flow paths is controlled.

[0023] In the preferred technical solution of the above-mentioned delayed defrost control method, a defrost sensor is provided on each of the heat exchange flow paths, and controlling the on / off state of each of the heat exchange flow paths based on the usage quantity and the frosting condition of each of the heat exchange flow paths further includes:

[0024] obtaining the defrost temperature of each of the defrost sensors;

[0025] Based on the defrost temperature, the on / off state of each of the heat exchange channels is controlled so that the heat exchange channels with a high defrost temperature are preferentially in an on state.

[0026] In the preferred technical solution of the above-mentioned delayed defrost control method, the delayed defrost control method further includes:

[0027] When the number of heat exchange flow paths in use is less than the number of heat exchange flow paths, determining whether the heat exchange flow paths currently in the passage state meet the defrosting condition;

[0028] If so, the heat exchange flow path is controlled to enter an off-circuit state, and the unused heat exchange flow path is controlled to enter an on-circuit state;

[0029] and / or

[0030] The delayed defrost control method further includes:

[0031] When all the heat exchange flow paths meet the defrosting conditions, all the heat exchange flow paths are controlled to enter the passage state and the defrosting mode is turned on.

[0032] In the preferred technical solution of the above-mentioned delayed defrost control method, the outdoor heat exchanger further includes a plurality of subcooling flow paths arranged in parallel. When the air-conditioning system is in heating mode, the plurality of subcooling flow paths can exchange heat with the plurality of heat exchange flow paths.

[0033] When the above technical solution is adopted, when the air-conditioning system is in heating mode, multiple supercooling pipes can melt the frost on the surfaces of multiple heat exchange flow paths, making the outdoor heat exchanger frost slower, thereby achieving the effect of delayed defrosting. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The outdoor heat exchanger of the present application is described below with reference to the accompanying drawings. In the drawings:

[0035] Figure 1 A schematic diagram of the air conditioning system of this application;

[0036] Figure 2This is a flow chart of the main steps of a delayed defrost control method according to an embodiment of the present application.

[0037] Reference Signs List

[0038] 1. Compressor; 2. Four-way reversing valve; a. First interface; b. Second interface; c. Third interface; d. Fourth interface; 3. Outdoor heat exchanger; 31. Heat exchange flow path; 311. Defrost sensor; 32. Subcooling flow path; 4. Throttling device; 5. Indoor heat exchanger; 6. Control valve. DETAILED DESCRIPTION

[0039] The following describes preferred embodiments of the present application with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to illustrate the technical principles of the present application and are not intended to limit the scope of protection of the present application. For example, the accompanying drawings only illustrate one possible air-conditioning system, but this is not intended to limit the scope of protection of the present application. Those skilled in the art may modify the specific configuration of the air-conditioning system as needed without departing from the principles of the present application.

[0040] It should be noted that, in the description of this application, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of this application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, "multiple" refers to at least two.

[0041] Furthermore, it should be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0042] Refer to the following Figure 1 To describe the outdoor heat exchanger and air conditioning system of this application, Figure 1 This is a schematic diagram of the air conditioning system of this application.

[0043] like Figure 1As shown, in a preferred embodiment, the air conditioning system includes a compressor 1, a four-way reversing valve 2, an outdoor heat exchanger 3, a throttling device 4, an indoor heat exchanger 5, and a control valve 6. There are multiple indoor heat exchangers 5, and the multiple indoor heat exchangers 5 are arranged in parallel and have two confluence ports at both ends of the multiple indoor heat exchangers 5. The outdoor heat exchanger 3 includes multiple heat exchange flow paths 31 arranged in parallel and multiple subcooling flow paths 32 arranged in parallel. The length of the heat exchange flow path 31 is greater than the length of the subcooling flow path 32, and the number of the heat exchange flow paths 31 is equal to the number of the subcooling flow paths 32. Specifically, in this embodiment, there are four heat exchange flow paths 31 and four subcooling flow paths 32, and the four heat exchange flow paths 31 and four subcooling flow paths 32 have two confluence ports at both ends. The heat exchange flow path 31 corresponds to the subcooling flow path 32 one by one, and each heat exchange flow path 31 is arranged adjacent to the corresponding subcooling flow path 32, so that heat exchange can be carried out between the heat exchange flow path 31 and the subcooling flow path 32, and a defrost sensor 311 is provided on each heat exchange flow path 31.

[0044] The exhaust port of compressor 1 is connected to the first port a of four-way reversing valve 2. The second port b of four-way reversing valve 2 is connected to the first confluence port (the upper port in the diagram) of multiple indoor heat exchangers 5. The second confluence ports (the lower port in the diagram) of multiple indoor heat exchangers 5 are connected to the first confluence port of four subcooling flow paths 32. The second confluence ports of the four subcooling flow paths 32 are connected to the first port (the right port in the diagram) of throttling device 4. The second port (the left port in the diagram) of throttling device 4 is connected to the first confluence port of four heat exchange flow paths 31. The second confluence ports of the four heat exchange flow paths 31 are connected to the third port c of four-way reversing valve 2. The fourth port d of four-way reversing valve 2 is connected to the return air port of compressor 1. Each heat exchange flow path 31 is provided with a control valve 6, which allows each heat exchange flow path 31 to be independently opened and closed.

[0045] In this embodiment, if the air conditioning system is in heating mode, the first port a of the four-way reversing valve 2 is connected to the second port b, and the third port c is connected to the fourth port d. The compressor 1 discharges high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant passes through the four-way reversing valve 2 and enters the indoor heat exchanger 5 to release heat. The refrigerant then enters the subcooling flow path 32 to achieve subcooling. Since the heat exchange flow path 31 and the subcooling flow path 32 are adjacent, frost on the surface of the heat exchange flow path 31 can be melted at this time. The refrigerant then passes through the throttling device 4 to reduce pressure, then enters the heat exchange flow path 31 to absorb heat and achieve superheating with the subcooling flow path 32. Finally, the refrigerant returns to the compressor through the four-way reversing valve 2, thereby completing the heating cycle. The provision of the subcooling flow path 22 allows frost on the surface of the heat exchange flow path 31 to be melted during heating operation, thereby achieving a delayed defrosting effect.

[0046] It should be explained that in this embodiment, the "parallel" in the indoor heat exchangers 5 being arranged in parallel, the multiple heat exchange paths 31 being arranged in parallel, or the multiple subcooling paths 32 being arranged in parallel only refers to the fact that they share a refrigerant inlet and a refrigerant outlet, and does not mean a circuit. In addition, although in this embodiment, the number of heat exchange paths 31 is equal to the number of subcooling paths 32, their arrangement is not fixed. In an alternative embodiment, the number of heat exchange paths 31 can be greater than or less than the number of subcooling paths 32. For example, four heat exchange paths 31 and three subcooling paths 32 are arranged, and in this case, the three subcooling paths 32 are arranged in the intervals between the four heat exchange paths 31. Conversely, three heat exchange paths 31 and four subcooling paths 32 can also be arranged, and in this case, the three heat exchange paths 31 are arranged in the intervals between the four subcooling paths 32. In addition, in this embodiment, the setting that the length of the heat exchange flow path 31 is greater than the length of the subcooling flow path 32 can ensure the heating capacity of the air-conditioning system, but its setting is not static. Those skilled in the art can change it according to needs. In an alternative embodiment, when the number of heat exchange flow paths 31 is greater than the number of subcooling flow paths 32, the length of the subcooling flow path 32 can also be greater than the length of the heat exchange flow path 31.

[0047] It should also be explained that, in this embodiment, each heat exchange flow path 31 is provided with a defrost sensor 311. The defrost sensor 311 can be used to determine the frosting condition of each heat exchange flow path 31. However, its setting is not fixed. In an alternative embodiment, only one defrost sensor 311 can be provided, that is, the overall frosting condition of the four heat exchange flow paths 31 is determined after the flow paths 31 merge. In addition, in this embodiment, the control valve 6 is configured as a solenoid valve, and each heat exchange flow path 31 can be independently switched on and off by the corresponding control valve 6. However, the setting of multiple control valves 6 is not fixed. In an alternative embodiment, those skilled in the art can change the specific setting of the control valve 6 as needed. In another alternative embodiment, the setting of multiple control valves 6 can be omitted, and this does not hinder the realization of the delayed defrosting effect of the subcooling flow path 32.

[0048] It will be understood by those skilled in the art that this embodiment only illustrates one possible air-conditioning system, but this is not intended to limit the scope of protection of this application. Without departing from the principles of this application, those skilled in the art can change the specific settings of the air-conditioning system as needed, and those skilled in the art can apply this application to other application scenarios. In an alternative embodiment, the components in the air-conditioning system can be added or reduced, and the settings of the refrigerant flow path can be changed. For example, a throttling device can be added between the second confluence ports of the multiple indoor heat exchangers 5 and the first confluence ports of the multiple subcooling flow paths 32. For another example, the number of indoor heat exchangers 5, heat exchange flow paths 31 or subcooling flow paths 32 can be changed, as long as it does not affect the normal function of the outdoor heat exchanger.

[0049] The present application also provides a delayed defrost control method for an air-conditioning system, the air-conditioning system including an outdoor heat exchanger and multiple indoor heat exchangers, the outdoor heat exchanger including multiple heat exchange paths arranged in parallel and multiple subcooling paths arranged in parallel, and each heat exchange path can be independently turned on and off, when the air-conditioning system is in heating mode, the multiple subcooling paths can exchange heat with the multiple heat exchange paths.

[0050] See below Figure 2 To describe the delayed defrost control method of the present application, Figure 2 This is a flow chart of the main steps of a delayed defrost control method according to an embodiment of the present application.

[0051] like Figure 2 As shown, in one possible implementation, the delayed defrost control method includes the following steps:

[0052] S201, when the air conditioning system is in heating mode, obtain the indoor unit load;

[0053] S202, determining the number of heat exchange paths to be used based on the internal unit load;

[0054] S203, based on the usage quantity, controlling the on-off state of each heat exchange flow path, so that a corresponding number of heat exchange flow paths are in an on state.

[0055] There is a corresponding relationship between the load of the internal unit and the number of heat exchange paths used.

[0056] It should be explained that in real life, one outdoor heat exchanger will be connected to multiple indoor heat exchangers, and in most cases, multiple indoor heat exchangers will not be turned on at the same time. Figure 1 The delayed defrost control method is described using the air conditioning system in [1]. Taking a 12HP outdoor heat exchanger 3 as an example, four heat exchange paths 31 and four subcooling paths 32 can be provided. Furthermore, the indoor unit load, i.e., the total load of the multiple indoor heat exchangers 5, can be divided into four load ranges, such as 0-3HP, 3-6HP, 6-9HP, and 9-12HP. For an indoor unit load of 0-3HP, the number of heat exchange paths 31 used is 1; for an indoor unit load of 3-6HP, the number of heat exchange paths 31 used is 2, and so on. Furthermore, variable-frequency air conditioning units adjust parameters such as the compressor operating frequency based on the indoor unit load. Therefore, obtaining the indoor unit load is a prior art and will not be further described here.

[0057] In this embodiment, when the air-conditioning system is turned on in heating mode, the indoor unit load can be obtained, and the number of heat exchange paths in use can be determined based on the corresponding relationship between the indoor unit load and the number of heat exchange paths in use. After determining the number of uses, the corresponding number of heat exchange paths can be placed in a passage state. That is to say, if the indoor unit load is between 3-6HP, the number of heat exchange paths in use at this time is 2, then only two of the four heat exchange paths are in a passage state and enter the heating cycle. When these two heat exchange paths are frosted, the other two unused heat exchange paths are switched to enter the heating cycle.

[0058] It should also be explained that in the prior art, the outdoor heat exchanger absorbs heat as a whole. However, due to factors such as varying humidity, frost may form unevenly on the surface of the outdoor heat exchanger. This means that defrost mode may be activated even when some pipes are not frosted. This results in frequent defrosting of the air conditioning system, reducing the air conditioning's heating efficiency and impacting the user's heating experience. In this embodiment, the number of heat exchange paths used is determined by the load of the internal units. This ensures uniform frost formation on the outdoor heat exchanger while ensuring heating capacity, thereby achieving a delayed defrost effect. Furthermore, the provision of a subcooling path allows frost on the surface of the heat exchange path to melt during the heating process, further achieving a delayed defrost effect.

[0059] Those skilled in the art will appreciate that, although the delayed defrost control method in this embodiment is described in conjunction with the outdoor heat exchanger and air conditioning system in the above-described embodiment, such configuration is not required. In an alternative embodiment, the subcooling flow path in the outdoor heat exchanger can be omitted. In this case, the above-described steps can also be used to achieve uniform frosting of the outdoor heat exchanger, thereby fully utilizing the outdoor heat exchanger and achieving the effect of delayed defrosting. In another alternative embodiment, those skilled in the art can modify the specific configuration of the air conditioning system as needed, as long as it does not affect the normal implementation of the delayed defrost control method of this application.

[0060] In some embodiments, the step S203 of “controlling the on / off state of each heat exchange flow path based on the usage quantity” further includes:

[0061] Based on the usage quantity and the frosting condition of each heat exchange flow path, the on-off state of each heat exchange flow path is controlled.

[0062] Furthermore, each heat exchange flow path is provided with a defrost sensor. Based on the usage amount and the frosting condition of each heat exchange flow path, controlling the on / off state of each heat exchange flow path further includes:

[0063] Get the defrost temperature of each defrost sensor;

[0064] Based on the defrost temperature, the on / off states of the various heat exchange paths are controlled so that the heat exchange paths with higher defrost temperatures are placed in an on state first.

[0065] In this embodiment, continue with Figure 1 The delayed defrost control method is described using the air conditioning system in FIG. When the air conditioner is turned on for heating, four defrost temperatures can be obtained from four defrost sensors 6. Based on these four defrost temperatures, i.e., the frost conditions of the four heat exchange paths 31, the on / off states of each heat exchange path 31 are controlled. For example, if the number of heat exchange paths 31 in use is determined to be two, the control valve 6 corresponding to each heat exchange path 31 can be adjusted to open the two heat exchange paths 31 with the highest defrost temperatures, while the other two heat exchange paths 31 are closed. In other words, when the air conditioner is turned on for heating, the heat exchange path 31 with the least frost is first put into the heating cycle, thereby ensuring the heating capacity of the air conditioning system and allowing users to heat up as quickly as possible.

[0066] It should be explained that the above steps are not fixed. In an alternative embodiment, the judgment of the frosting condition of each heat exchange flow path can be omitted. Figure 1 Taking the direction shown as an example, the heat exchange paths 31 can be ordered from left to right. If the number of heat exchange paths 31 in use is determined to be 2, the heat exchange paths 31 numbered 1 and 2 are first controlled to enter the heating cycle. In another alternative embodiment, the heat exchange paths with lower defrost temperatures can be prioritized. However, if the user is to heat up as quickly as possible, prioritizing the heat exchange paths with higher defrost temperatures is a more preferred option.

[0067] In some embodiments, the delayed defrost control method further comprises:

[0068] When the number of heat exchange flow paths in use is less than the number of heat exchange flow paths, determining whether the heat exchange flow paths currently in the passage state meet the defrosting conditions;

[0069] If so, the heat exchange flow path is controlled to enter an off-circuit state, and the unused heat exchange flow path is controlled to enter an on-circuit state.

[0070] In this embodiment, there is a situation where the number of heat exchange channels in use equals the total number of heat exchange channels. In this case, all heat exchange channels will enter the heating cycle, and the heat exchange channels do not need to be switched. However, if the number of heat exchange channels in use is less than the total number of heat exchange channels, there will be unused heat exchange channels. If an active heat exchange channel has frosted, that is, a heat exchange channel currently in the open state has reached the defrost condition, then it is necessary to close that heat exchange channel and open the unused heat exchange channel. When all heat exchange channels reach the defrost condition, all heat exchange channels are controlled to enter the open state, and the defrost mode is activated.

[0071] It should be explained that when judging whether the heat exchange flow path has reached the defrost condition, the defrost logic in the prior art can be used. For example, by comparing the defrost temperature with the preset temperature threshold to judge whether the heat exchange flow path has reached the defrost condition, which will not be described in detail here. In addition, in actual use, in order to ensure that the heating capacity of the air-conditioning system is attenuated below a certain level, the preset temperature threshold in this embodiment can be higher than the preset temperature threshold in the prior art. In addition, the above-mentioned switching method is not static. In an alternative embodiment, taking the determined number of heat exchange flow paths to be used as 2 as an example, it is possible to switch to the other two heat exchange flow paths after both heat exchange flow paths have reached the defrost condition.

[0072] Those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of this application and to form different embodiments. For example, in the claims of this application, any of the claimed embodiments may be used in any combination.

[0073] Thus far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present application.

Claims

1. An outdoor heat exchanger, characterized in that: The outdoor heat exchanger includes a heat exchange flow path and a subcooling flow path, and the heat exchange flow path and the subcooling flow path are capable of exchanging heat. The heat exchange flow path and the subcooling flow path are both provided in plurality, the plurality of heat exchange flow paths are provided in parallel, and two ends of the plurality of heat exchange flow paths have two confluence ports, and the plurality of subcooling flow paths are provided in parallel, and two ends of the plurality of subcooling flow paths have two confluence ports; The two confluence ports of the plurality of heat exchange paths are respectively used to connect to the compressor and the throttling device, and the two confluence ports of the plurality of subcooling paths are respectively used to connect to the indoor heat exchanger and the throttling device.

2. The outdoor heat exchanger according to claim 1, characterized in that The number of the heat exchange flow paths is equal to the number of the subcooling flow paths, and the heat exchange flow paths correspond to the subcooling flow paths one by one, and each heat exchange flow path is arranged adjacent to the corresponding subcooling flow path.

3. The outdoor heat exchanger according to claim 1, characterized in that The length of the heat exchange flow path is greater than the length of the subcooling flow path.

4. The outdoor heat exchanger according to claim 1, characterized in that The outdoor heat exchanger further includes a plurality of defrost sensors, the number of the heat exchange flow paths is equal to the number of the defrost sensors, and each of the heat exchange flow paths is provided with a defrost sensor; and / or The outdoor heat exchanger further includes a plurality of control valves. The number of the heat exchange flow paths is equal to the number of the control valves. One control valve is provided on each heat exchange flow path so that each heat exchange flow path can be independently opened and closed.

5. An air conditioning system, characterized in that: The air conditioning system includes the outdoor heat exchanger according to any one of claims 1 to 4.

6. A delayed defrost control method for an air conditioning system, characterized in that: The air conditioning system includes an outdoor heat exchanger and multiple indoor heat exchangers, the outdoor heat exchanger includes multiple heat exchange flow paths arranged in parallel, and each of the heat exchange flow paths can be independently opened and closed; The delayed defrost control method comprises: When the air conditioning system is in heating mode, obtaining the load of the indoor unit; determining the number of heat exchange paths to be used based on the internal machine load; Based on the usage quantity, controlling the on / off state of each of the heat exchange flow paths so that a corresponding number of the heat exchange flow paths are in an on state; There is a corresponding relationship between the internal machine load and the number of heat exchange paths in use.

7. The delayed defrost control method according to claim 6, characterized in that: The controlling of the on / off state of each heat exchange flow path based on the usage quantity further includes: Based on the usage quantity and the frosting condition of each of the heat exchange flow paths, the on-off state of each of the heat exchange flow paths is controlled.

8. The delayed defrost control method according to claim 7, characterized in that: Each of the heat exchange flow paths is provided with a defrost sensor, and the controlling of the on / off state of each of the heat exchange flow paths based on the usage quantity and the frosting condition of each of the heat exchange flow paths further comprises: obtaining the defrost temperature of each of the defrost sensors; Based on the defrost temperature, the on / off state of each of the heat exchange channels is controlled so that the heat exchange channels with a high defrost temperature are preferentially in an on state.

9. The delayed defrost control method according to claim 8, characterized in that: The delayed defrost control method further includes: When the number of heat exchange flow paths in use is less than the number of heat exchange flow paths, determining whether the heat exchange flow paths currently in the passage state meet the defrosting condition; If so, the heat exchange flow path is controlled to enter an off-circuit state, and the unused heat exchange flow path is controlled to enter an on-circuit state; and / or The delayed defrost control method further includes: When all the heat exchange flow paths meet the defrosting conditions, all the heat exchange flow paths are controlled to enter the passage state and the defrosting mode is turned on.

10. The delayed defrost control method according to any one of claims 6 to 9, characterized in that: The outdoor heat exchanger further includes a plurality of subcooling flow paths arranged in parallel. When the air-conditioning system is in a heating mode, the plurality of subcooling flow paths can exchange heat with the plurality of heat exchange flow paths.

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