Control method of an evaporator and air conditioner

Abstract

The application discloses a control method of an evaporator and an air conditioner, and the control method comprises the following steps: detecting the refrigerant temperature at the outlet of each branch of the evaporator and the temperature at the inlet of the compressor; if the absolute value of the difference between the refrigerant temperatures at the outlets of two branches is greater than a first temperature difference threshold, determining whether the refrigerant at the outlet of the evaporator branch is in a supercooling state or a superheating state according to the refrigerant temperature at the outlet of the evaporator branch and the temperature at the inlet of the compressor; if yes, adjusting the operating parameters of the evaporator until the supercooling state or the superheating state is eliminated, so that the technical problems of liquid entrainment in the suction of the compressor, low heat exchange efficiency of the evaporator and easy condensation caused by uneven distribution of liquid among the branches of the evaporator in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of evaporator control technology, and in particular to a control method for an evaporator and an air conditioner. Background Technology

[0002] Currently, most air conditioning refrigeration systems use finned heat exchangers as evaporators. However, in actual operation, issues such as varying evaporator branch lengths, high local resistance in some branches, uneven evaporator face velocity, and poor compressor oil return lead to inconsistent oil levels in each branch. Furthermore, the use of bends after throttling generates centrifugal force, disrupting the uniformity of two-phase fluid flow. These issues result in uneven liquid distribution within the evaporator. Uneven distribution causes some branches to have excessive refrigerant, leading to incomplete evaporation and liquid-laden compressor operation. Conversely, some branches have insufficient refrigerant, failing to fully utilize the evaporator's heat exchange area and resulting in cooling capacity below design value. Additionally, temperature differences between evaporator pipes create secondary heat conduction, further reducing evaporator heat exchange efficiency. Moreover, the temperature differences between evaporator branches create temperature differences with the airflow after heat exchange with the evaporator. The convergence of these temperature-differentiated airflows easily leads to condensation in the ductwork, negatively impacting user experience.

[0003] There is currently no effective solution to the technical problems in the above-mentioned technologies, such as liquid carryover in compressor suction, low heat exchange efficiency of evaporator, and easy condensation caused by uneven liquid distribution between the branches of the evaporator. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a control method for an evaporator and an air conditioner to solve the technical problems in the related art, such as liquid carry-in of the compressor air, low heat exchange efficiency of the evaporator, and easy condensation caused by uneven liquid distribution between the branches of the evaporator.

[0005] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0006] According to one aspect of the present invention, a method for controlling an evaporator is provided, comprising:

[0007] Detect the refrigerant temperature at the outlet of each branch of the evaporator and the inlet temperature of the compressor;

[0008] If the absolute value of the temperature difference between the refrigerant outlets of two branches is greater than the first temperature difference threshold, then the refrigerant in the evaporator branch is determined to be in an undercooled or overheated state based on the refrigerant temperature at the outlet of the evaporator branch and the compressor inlet temperature.

[0009] If so, adjust the operating parameters of the evaporator until the subcooling or overheating state is relieved.

[0010] Optionally, adjusting the operating parameters of the evaporator specifically includes:

[0011] If the refrigerant in the evaporator branch is in the subcooled state, the speed of the fan corresponding to that branch is increased.

[0012] Optionally, the number of evaporator branches in the subcooled state is negatively correlated with the increase in fan speed.

[0013] Optionally, adjusting the operating parameters of the evaporator specifically includes:

[0014] If the refrigerant in the evaporator branch is in the superheated state, the refrigerant flow rate in that branch is increased.

[0015] Optionally, determining whether the refrigerant in the evaporator branch is in a subcooled or superheated state based on the refrigerant temperature at the evaporator branch outlet and the compressor inlet temperature specifically includes:

[0016] If the refrigerant temperature at the outlet of the evaporator branch is greater than or equal to the compressor inlet temperature, the refrigerant in that branch is determined to be in a superheated state.

[0017] Optionally, determining whether the refrigerant in the evaporator branch is in a subcooled or superheated state based on the refrigerant temperature at the evaporator branch outlet and the compressor inlet temperature specifically includes:

[0018] If the refrigerant temperature at the outlet of each branch of the evaporator is lower than the inlet temperature of the compressor, the difference between the inlet temperature of the compressor and the outlet temperature of the evaporator branch is calculated. If the difference is greater than the second temperature difference threshold, the refrigerant in the evaporator branch is determined to be in the subcooled state.

[0019] Optionally, if the difference between the compressor inlet temperature and the refrigerant temperature at the outlet of each branch of the evaporator is less than or equal to the second temperature difference threshold, the current operating state of the evaporator is maintained.

[0020] Optionally, if the absolute value of the difference between the refrigerant temperatures at any two branch outlets in each evaporator is less than or equal to the first temperature difference threshold, then the current operating state of the evaporator is maintained.

[0021] According to another aspect of the present invention, an air conditioner is provided, comprising an evaporator, a compressor, and a control unit, wherein the evaporator includes at least two branches:

[0022] The air conditioner also includes:

[0023] The first temperature sensing device is used to detect the refrigerant temperature at the outlet of each branch of the evaporator;

[0024] The second temperature sensing device is used to detect the compressor inlet temperature;

[0025] The first temperature sensing device and the second temperature sensing device are respectively connected to the control unit via signal connection;

[0026] The control unit is used to: if the absolute value of the difference between the refrigerant temperatures at the outlets of two branches is greater than a first temperature difference threshold, determine whether the refrigerant in the evaporator branch is in a subcooled or overheated state based on the refrigerant temperature at the outlet of the evaporator branch and the compressor inlet temperature.

[0027] If so, adjust the operating parameters of the evaporator until the subcooling or overheating state is relieved.

[0028] Optionally, each branch of the evaporator is equipped with a set of fans, and the air ducts corresponding to the fans of each branch are separated by partitions.

[0029] This invention provides a control method for an evaporator and an air conditioner. The method detects the refrigerant temperature at the outlet of each branch of the evaporator and the compressor inlet temperature. If the absolute value of the temperature difference between two branches exceeds a first temperature difference threshold, it further determines whether the refrigerant in the branch is in a subcooled or overheated state based on the refrigerant temperature at the branch outlet and the compressor inlet temperature. If so, the operating parameters of the evaporator are adjusted until the subcooled or overheated state is resolved, making the refrigerant temperature at the outlet of each branch more uniform. This ensures uniform liquid distribution in each branch, solving the technical problems in related technologies such as liquid carryover in compressor suction, low evaporator heat exchange efficiency, and easy condensation caused by uneven liquid distribution between evaporator branches. Attached Figure Description

[0030] Figure 1 A flowchart illustrating an evaporator control method provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of an evaporator in an air conditioner provided by an embodiment of the present invention;

[0032] Figure 3 for Figure 2 AA view;

[0033] Figure 4 for Figure 2 BB view;

[0034] Figure 5 A flowchart illustrating an evaporator control method according to another embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of the topology of a control system in an air conditioner provided for an embodiment of the present invention. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0037] In related technologies, uneven liquid distribution between different branches of the evaporator can lead to problems such as liquid carryover in the compressor suction, low evaporator heat exchange efficiency, and easy condensation. Currently, there is no satisfactory solution.

[0038] To address the aforementioned problems, this invention proposes a control method for an evaporator, thereby resolving these technical issues in related technologies. A detailed description follows.

[0039] According to embodiments of the present invention, a control method for an evaporator is provided, combined with Figure 1 The method includes:

[0040] Step S101: Detect the refrigerant temperature at the outlet of each branch of the evaporator and the compressor inlet temperature.

[0041] In this embodiment, the evaporator includes at least two branches, each corresponding to a set of fans. That is, the heat exchange tubes of each branch are aligned with the fan ducts. The fans drive the airflow around the branch to exchange heat with the refrigerant in that branch, evaporating the liquid refrigerant in the evaporator and sending it to the compressor. Figure 2-4 Taking the evaporator 1 in the air conditioner 3 as an example, it includes an evaporator side 5 and three branches, namely the first branch, the second branch, and the third branch. Each branch is equipped with a set of fans 2, namely the first fan, the second fan, and the third fan. In some preferred embodiments, the air ducts corresponding to each set of fans are also separated by partitions 4 to prevent the lower-speed fans from reversing when the speed of some of the fans is increased (as described in the embodiments below).

[0042] A first temperature sensing device, such as a temperature sensing bulb, is installed on the outlet pipe of each branch of the evaporator to detect the refrigerant temperature at the outlet of the evaporator branch. Taking three branches as an example, their outlet refrigerant temperatures are denoted as T1, T2, and T3, respectively. In addition, a second temperature sensing device, such as a temperature sensing bulb, is installed on the pipe at the compressor inlet to detect the temperature value at the compressor inlet, i.e., the suction temperature, which is denoted as suction temperature T in this embodiment. s In addition, a return air temperature sensor can be installed at the evaporator return air inlet to detect the return air temperature T. 回风 .

[0043] Step S103: If the absolute value of the temperature difference between the refrigerant outlets of two branches is greater than the first temperature difference threshold, then determine whether the refrigerant in the evaporator branch is in a subcooled or overheated state based on the refrigerant temperature at the outlet of the evaporator branch and the compressor inlet temperature.

[0044] As an example, let the first temperature difference threshold be ΔT1. In the three evaporator branches described in the above embodiment, calculate the absolute value of every two temperature differences in the refrigerant temperature at the outlet of each of the three branches, i.e., |T1-T2|, |T1-T3|, |T2-T3|. Then compare this value with ΔT1. If each difference is ≤ ΔT1, it is determined that the liquid distribution in the evaporator is relatively uniform, and the evaporator of the air conditioner continues to operate in the current state. Otherwise, it is determined that the liquid distribution between the branches of the evaporator is uneven. In this embodiment, the reference value for ΔT1 is 2℃.

[0045] Under normal operating conditions, the refrigerant temperature at the outlet of each branch of the evaporator should be approximately the same. However, as mentioned earlier, issues such as varying branch lengths, high local resistance in some branches, uneven evaporator frontal air velocity, and poor compressor oil return lead to inconsistent oil levels in each branch. Furthermore, the use of bends after throttling generates centrifugal force, disrupting the uniformity of the two-phase fluid flow. These factors result in uneven liquid distribution in the evaporator. This uneven distribution manifests as an excessively large temperature difference between the outlets of the branches, exceeding a reasonable range. Step S103 compares the absolute value of the temperature difference between each branch with a preset first temperature difference threshold of ΔT1. Once this threshold is exceeded, the problem of uneven liquid distribution between the evaporator branches can be detected promptly, allowing for further adjustments to the evaporator branch operation control strategy to restore a more uniform liquid distribution.

[0046] In step S103, if it is determined that each evaporator branch is in a state of uneven liquid distribution, it is necessary to further determine which branch is in a state of undercooling or overheating, that is, which branch is causing the uneven liquid distribution due to undercooling or overheating.

[0047] After determining that the branch is in an overcooled or overheated state, the overcooled or overheated state is further relieved by adjusting the operating parameters of the evaporator, that is: execute step S105, if so, adjust the operating parameters of the evaporator until the overcooled or overheated state is relieved.

[0048] Under normal conditions, since there is still a certain distance of pipeline between the evaporator branch outlet and the compressor inlet, this pipeline will exchange heat with the external environment. Therefore, the refrigerant temperature at the evaporator branch outlet is allowed to be slightly lower than the compressor inlet temperature, and the two should be kept within a reasonable temperature difference range. Otherwise, it can be determined that the temperature at the evaporator branch outlet is too low or too high, that is, the refrigerant is in an overcooled or overheated state.

[0049] For example, if the outlet temperature of a certain branch of the evaporator is too low, it indicates that the refrigerant in that branch is in a subcooled state and has not been able to completely evaporate and exchange heat in the heat exchange tubes of the evaporator branch, meaning that the refrigerant flow rate is too high relative to the heat exchange area. Accordingly, in step S105, the heat exchange efficiency of that branch can be improved by increasing the air velocity flowing through it, so that it can completely evaporate and exchange heat, making full use of the evaporator heat exchange area.

[0050] Conversely, when the outlet temperature of a certain branch of the evaporator is too high, it indicates that the refrigerant in that branch is already in a superheated state, that is, the refrigerant flow rate is too low relative to the heat exchange area. In this case, in step S105, the refrigerant flow rate of that branch can be increased by opening the refrigerant throttling mechanism, such as the opening of the expansion valve.

[0051] Below, we will use more specific examples to introduce the judgment logic of the branch outlet undercooling or overheating state in step S103, and the specific adjustment strategy of the evaporator operating parameters in step S105.

[0052] As an example, in step S103, if the refrigerant temperature at the outlet of the evaporator branch is greater than or equal to the compressor inlet temperature, it is determined that the refrigerant in that branch is in a superheated state.

[0053] For example, after confirming the uneven liquid distribution between the branches of the evaporator in step S103, the refrigerant temperature at the outlet of each branch is compared with the compressor inlet temperature. As mentioned earlier, under normal conditions, the refrigerant temperature at the evaporator outlet should be slightly lower than the compressor inlet temperature. Therefore, if the refrigerant temperature at the outlet of a certain evaporator branch is greater than or equal to the compressor inlet temperature, it is determined that the refrigerant in that branch is in a superheated state. In step S105, adjusting the operating parameters of the evaporator specifically involves increasing the refrigerant flow rate of that branch. For example, the opening of the electronic expansion valve of that branch can be increased to increase the flow rate of refrigerant into that branch, allowing the refrigerant to make fuller use of the heat exchange area in the evaporator branch, carrying away more heat and lowering the refrigerant temperature at the outlet of that branch. Then, the refrigerant temperature at the outlet of each branch of the evaporator is continuously monitored until it is lower than the compressor inlet temperature.

[0054] Next, as an example, in step S103, if the refrigerant temperature at the outlet of each branch of the evaporator is lower than the compressor inlet temperature, the difference between the compressor inlet temperature and the refrigerant temperature at the outlet of the evaporator branch is calculated. If this difference is greater than the second temperature difference threshold, the refrigerant in the evaporator branch is determined to be in the subcooled state. In this embodiment, the second temperature difference threshold is denoted as ΔT2, and the reference value is 3℃.

[0055] As mentioned earlier, under normal conditions, the refrigerant temperature at the evaporator outlet should be slightly lower than the compressor inlet temperature, but the two still need to be kept within a reasonable temperature difference range. Therefore, in step S103, the difference between the compressor inlet temperature and the refrigerant temperature at the outlet of each branch of the evaporator is calculated. If a certain difference is detected to be greater than the preset second temperature difference threshold ΔT2, it is determined that the refrigerant in that branch is in a subcooled state. At this time, the refrigerant may not have completely evaporated and is still in a liquid state. If it is sent into the compressor, it may cause compressor liquid slugging. Therefore, accordingly, in step S105, the fan speed corresponding to that branch can be increased to improve the heat exchange efficiency of the refrigerant, so that it can be fully evaporated into a gaseous state before being sent into the compressor.

[0056] Adjusting the fan speed can be achieved by adjusting the fan's operating voltage or frequency. For example, since the fan control voltage is linearly related to the speed, the fan speed can be increased by increasing the fan control voltage.

[0057] Conversely, if the difference between the compressor inlet temperature and the refrigerant temperature at each branch outlet of the evaporator is less than or equal to the second temperature difference threshold, the current operating state of the evaporator is maintained.

[0058] After completing step S105, you can return to step S101 to monitor the temperature of each branch of the evaporator in real time or periodically, so as to gradually adjust the refrigerant temperature at the outlet of each branch to be consistent and keep the temperature difference between the outlet and the compressor inlet within the second temperature difference threshold range.

[0059] Optionally, the number of evaporator branches in the subcooled state is negatively correlated with the increase in fan speed; that is, the more evaporator branches in the subcooled state, the lower the increase in fan speed. This control strategy is adopted because when there are many evaporator branches in the subcooled state, more fans need to increase their speed simultaneously. In this case, the lower-speed fans may be disturbed by the instantaneous speed increase of other high-speed fans, resulting in reverse rotation. The more fans that increase their speed simultaneously, the more significant this effect becomes. Therefore, for cases with a large number of evaporator branches in the subcooled state, the speed of the corresponding fans can be fine-tuned first to prevent the instantaneous speed increase of multiple fans from being too large, causing other lower-speed fans to reverse.

[0060] Since after step S105 is completed, it is necessary to return to step S101 to re-execute the evaporator branch subcooling state judgment process, if the above fine-tuning is insufficient to relieve the subcooling state of all branches, for example, some branches return to normal refrigerant temperature after fine-tuning, while the rest are still in a subcooling state, the fan speed of the remaining branches can be further adjusted after the re-judgment process. This step-by-step adjustment strategy ensures that many subcooled branches of the evaporator can return to normal state, while also preventing multiple fan speeds from increasing too much instantaneously, causing other fans with lower speeds to reverse.

[0061] In addition to preventing some fans from reversing by controlling the increase in fan speed in the above embodiments, in other embodiments, baffles can be set between the air ducts corresponding to the fans of each branch of the evaporator. In this way, the heat exchange pipeline of the evaporator is divided into several independent small heat exchange units. Since the air ducts are isolated from each other, when the speed of individual fans is too high, it can prevent the fans with lower speeds from reversing.

[0062] After the refrigerant is de-cooled or de-heated in each branch, the refrigerant temperature at the outlet of each branch tends to be consistent and remains within the first temperature difference threshold range. This ensures that the liquid distribution in the evaporator is relatively uniform and that it can fully evaporate and exchange heat, preventing various problems caused by uneven liquid distribution in the evaporator.

[0063] Taking an evaporator with three branch circuits as an example, this embodiment of the invention provides a control method for an evaporator, combined with... Figure 5 ,include:

[0064] After the air conditioner is turned on, the three fans run with the same initial control voltage V0. After the air conditioner has been running stably for 60 seconds, the refrigerant temperature T1, T2, and T3 at each outlet of the evaporator are detected. It is then determined whether |T1-T2|, |T1-T3|, and |T2-T3| are all less than or equal to ΔT1.

[0065] If so, that is, the absolute value of each difference is ≤ ΔT1, then the liquid distribution in the evaporator is relatively uniform, and the air conditioner continues to operate in the current state.

[0066] If not, that is, if the absolute value of any of the differences is greater than ΔT1, then first determine the relationship between T1, T2, T3 and T... s The size, i.e., whether at least one outlet temperature is greater than T. s If so, that is, any one of T1, T2, or T3 is greater than T. s If the refrigerant flow rate of that branch is considered low relative to the heat exchange area, the electronic expansion valve opening B1 is increased, and then T1, T2, T3 and T are continuously monitored. s The size, until T1, T2, and T3 are all less than T. s When T1, T2, and T3 are all less than Ts Then calculate T respectively s -T1、T s -T2、T s -T3. If T s -T1、T s -T2、T s If the difference between T1 and T2 is less than or equal to ΔT2, then the evaporator is kept in its current state. If any one of the differences is greater than ΔT2, then the refrigerant flow rate in that branch is considered too high, failing to complete evaporation and heat exchange. The fan voltage of that branch is increased by ΔV1 to improve the heat exchange efficiency of that branch and ensure sufficient heat exchange of the refrigerant. Then, the process returns to step one, continuously monitoring |T1-T2|, |T1-T3|, and |T2-T3| and further adjusting the fan control voltage. If the difference between two of the differences is greater than ΔT2, then the fan voltage of those two branches is increased by ΔV2. Then, the process continues to monitor |T1-T2|, |T1-T3|, and |T2-T3| and further adjust the fan control voltage. If the difference between all three branches is greater than ΔT2, then the fan voltage of all branches is increased by ΔV3. Then, the process continues to monitor |T1-T2|, |T1-T3|, and |T2-T3| and further adjust the fan control voltage.

[0067] Optionally, ΔV1 ≥ ΔV2 ≥ ΔV3. Especially when ΔV1 > ΔV2 > ΔV3, as mentioned earlier, this has the advantage of preventing excessive instantaneous increases in the speed of multiple fans from causing other fans with lower speeds to reverse. Of course, in some other embodiments, ΔV3 is less than ΔV1 and ΔV2, and there is no fixed relationship between ΔV1 and ΔV2. This is because after adjusting all three fans together, it is still necessary to determine whether to adjust the speed of one or two more fans. Therefore, each time all three fans are adjusted together, a fine-tuning is performed first, i.e., ΔV3 is minimized.

[0068] By using the above control methods, the temperature differences between each outlet of the evaporator (T1, T2, T3) can be controlled within ΔT1, and the temperature difference with the compressor inlet can be controlled within ΔT2, thereby ensuring that the liquid distribution in the evaporator is relatively uniform and that it can fully evaporate and exchange heat.

[0069] This invention also provides an air conditioner, including an evaporator, a compressor, and a control unit, wherein the evaporator includes at least two branches:

[0070] The air conditioner further includes: a first temperature sensing device for detecting the refrigerant temperature at the outlet of each branch of the evaporator; a second temperature sensing device for detecting the compressor inlet temperature; the first and second temperature sensing devices are respectively connected to the control unit; the control unit is configured to: if the absolute value of the difference between the refrigerant temperatures at the outlets of two branches is greater than a first temperature difference threshold, determine whether the refrigerant in the evaporator branch is in a subcooled or overheated state based on the refrigerant temperature at the outlet of the evaporator branch and the compressor inlet temperature; if so, adjust the operating parameters of the evaporator until the subcooled or overheated state is resolved.

[0071] Combination Figure 6 As described above, as an example, the control system of this air conditioner includes a control unit. The output terminals of the first temperature sensor and the second temperature sensor are respectively connected to the signal input terminal of the control unit. The output terminal of the control unit signal is respectively connected to the expansion valve and the fan. The overheating state described in the previous embodiment is relieved by adjusting the opening of the expansion valve, and the overcooling state described in the previous embodiment is relieved by increasing the fan speed.

[0072] The specific judgment logic and control strategy of the control unit in the above embodiments can be referred to the description in the method embodiments, and will not be repeated here.

[0073] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0074] In the embodiments provided in this application, the described device embodiments are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces, indirect couplings, or communication connections between units or modules, and may be electrical or other forms.

[0075] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0076] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0077] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for controlling an evaporator, characterized in that, include: Detect the refrigerant temperature at the outlet of each branch of the evaporator and the inlet temperature of the compressor; If the absolute value of the temperature difference between the refrigerant outlets of two branches is greater than the first temperature difference threshold, then the refrigerant in the evaporator branch is determined to be in an undercooled or overheated state based on the refrigerant temperature at the outlet of the evaporator branch and the compressor inlet temperature. If so, adjust the operating parameters of the evaporator until the subcooling or overheating state is relieved; The method of determining whether the refrigerant in the evaporator branch is in a subcooled or superheated state based on the refrigerant temperature at the evaporator branch outlet and the compressor inlet temperature specifically includes: If the refrigerant temperature at the outlet of the evaporator branch is greater than or equal to the compressor inlet temperature, the refrigerant in that branch is determined to be in a superheated state. If the refrigerant temperature at the outlet of each branch of the evaporator is lower than the inlet temperature of the compressor, then the difference between the inlet temperature of the compressor and the outlet temperature of the evaporator branch is calculated. If the difference is greater than the second temperature difference threshold, then the refrigerant in the evaporator branch is determined to be in the subcooled state. If the difference between the compressor inlet temperature and the refrigerant temperature at the outlet of each branch of the evaporator is less than or equal to the second temperature difference threshold, then the current operating state of the evaporator is maintained. If the absolute value of the difference between the refrigerant temperatures at any two branch outlets in each evaporator is less than or equal to the first temperature difference threshold, then the current operating state of the evaporator is maintained. The reference value for the first temperature difference threshold is 2℃; The reference value for the second temperature difference threshold is 3℃.

2. The evaporator control method according to claim 1, characterized in that, The adjustment of the evaporator's operating parameters specifically includes: If the refrigerant in the evaporator branch is in the subcooled state, the speed of the fan corresponding to that branch is increased.

3. The evaporator control method according to claim 2, characterized in that, The number of evaporator branches in the subcooled state is negatively correlated with the increase in fan speed.

4. The evaporator control method according to claim 1, characterized in that, The adjustment of the evaporator's operating parameters specifically includes: If the refrigerant in the evaporator branch is in the superheated state, the refrigerant flow rate in that branch is increased.

5. An air conditioner, comprising an evaporator, a compressor, and a control unit, characterized in that, The control unit is used to execute the control method of the evaporator as described in any one of claims 1 to 4; The evaporator includes at least two branches; The air conditioner also includes: The first temperature sensing device is used to detect the refrigerant temperature at the outlet of each branch of the evaporator; The second temperature sensing device is used to detect the compressor inlet temperature; The first temperature sensing device and the second temperature sensing device are respectively connected to the control unit via signal connection.

6. The air conditioner according to claim 5, characterized in that, Each branch of the evaporator is equipped with a set of fans, and the air ducts corresponding to the fans of each branch are separated by partitions.

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