Control method of fresh air air conditioning and fresh air air conditioning system

Abstract

The present invention relates to a control method for a fresh air air conditioner and a fresh air air conditioner system, wherein the method is applied to a fresh air air conditioner system, which includes a fresh air unit, an air conditioning box and a main control component. The air outlet of the fresh air unit is transported to the surface cooler of the air conditioning box; when the external fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and transports the dehumidified fresh air to the surface cooler of the air conditioning box; when the primary return air needs to be dehumidified, the main control component controls the air conditioning box to perform a dehumidification operation on the primary return air. Since the dehumidification mode of the fresh air unit and the air conditioning box in the fresh air air conditioner is single-point controlled, the temperature and humidity control of the fresh air unit and the air conditioning box are independent. After the fresh air processed by the fresh air unit is transported to the surface cooler of the air conditioning box, such a structural design and control method can reflect the best energy-saving effect regardless of whether the fresh air needs to be dehumidified, effectively improving energy saving and having a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the field of heating and ventilation, and in particular to a control method for a fresh air air conditioner and a fresh air air conditioner system. Background Art

[0002] In areas requiring cleanliness, air conditioning units (AHUs) are often used to maintain stable temperature and humidity control. However, outdoor fresh air is a significant source of interference, representing the primary source of fluctuations in the AHU's temperature. This led to the concept of fresh air handling units (MAUs). Many electronics and pharmaceutical manufacturing plants are equipped with dedicated MAUs for pre-conditioning.

[0003] In the prior art, after the fresh air handling unit (MAU) is configured, considering the energy-saving and emission-reduction effects of the air-conditioning system, the dehumidification of the fresh air is designed to be undertaken by the surface cooler of the fresh air handling unit (MAU). Before the fresh air treated by the MAU is delivered to the surface cooler of the air-conditioning unit (AHU), the fresh air treated by the MAU is mixed with the primary return air at the inlet of the air-conditioning unit (AHU). This design method allows the primary return air to be used to heat the fresh air when the fresh air needs to be dehumidified but the primary return air does not need to be dehumidified, saving energy consumption for the reheat coil. When both the fresh air and the primary return air need to be dehumidified, the heat exchange contact time is affected due to the large air volume passing through the surface cooler of the air-conditioning unit (AHU), which affects the heat exchange effect.

[0004] However, when the fresh air does not need to be dehumidified but the return air needs to be dehumidified, not only does the large air volume of the AHU surface cooler of the air-conditioning box affect the heat exchange effect, but that part of the fresh air is also needlessly cooled and heated, consuming energy. This results in an unsatisfactory energy-saving effect when the fresh air does not need to be dehumidified but the return air needs to be dehumidified. Summary of the Invention

[0005] In view of the above-mentioned defects in the prior art, the present invention provides a control method and a fresh air air conditioning system with better energy-saving effect, good performance and good adaptability.

[0006] In order to achieve the above-mentioned object, the control method of the fresh air air conditioner and the fresh air air conditioner system of the present invention have the following structures:

[0007] The control method of the fresh air air conditioner is mainly characterized by being applied to a fresh air air conditioner system, wherein the fresh air air conditioner system includes a fresh air unit, an air conditioning box, and a main control component, wherein the main control component is connected to the fresh air unit and the air conditioning box, respectively, and the air output of the fresh air unit is delivered to the surface cooler of the air conditioning box; the control method of the fresh air air conditioner comprises:

[0008] When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box;

[0009] When the primary return air needs to be dehumidified, the main control component controls the air-conditioning box to perform a dehumidification operation on the primary return air.

[0010] The above-mentioned control method of the fresh air air conditioner, wherein, when it is detected that the dew point temperature of the external fresh air is greater than or equal to the machine dew point temperature of the air-conditioning box, it is determined that the external fresh air needs to be dehumidified; when it is detected that the dew point temperature of the external fresh air is less than the machine dew point temperature of the air-conditioning box, it is determined that the external fresh air does not need to be dehumidified, wherein, when multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

[0011] The above-mentioned control method of the fresh air air conditioner, wherein, when the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, the air outlet temperature of the fresh air unit is the machine dew point temperature of the air-conditioning box, wherein, when multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

[0012] The above-mentioned control method of the fresh air air conditioner, wherein the control method of the fresh air air conditioner further includes:

[0013] When the outside fresh air does not need to be dehumidified, the temperature of the outside fresh air is compared with the supply air temperature of the air conditioning box;

[0014] If the temperature of the outside fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled to be below the supply air temperature of the air-conditioning box; if the temperature of the outside fresh air is lower than the supply air temperature of the air-conditioning box, the surface cooler of the fresh air unit is controlled to stop working, and only the fan of the fresh air unit is controlled to continue running.

[0015] The above-mentioned control method of the fresh air air conditioner, wherein if the temperature of the outside fresh air is greater than or equal to the supply air temperature of the air conditioning box, the outlet air temperature of the fresh air unit is controlled to be below the supply air temperature of the air conditioning box, specifically:

[0016] If the temperature of the external fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled within a temperature range of 1 to 2°C lower than the supply air temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the supply air temperature of the air-conditioning box is the supply air temperature of the air-conditioning box with the lowest supply air temperature among the air-conditioning boxes.

[0017] The above-mentioned control method of the fresh air air conditioner, wherein the control method of the fresh air air conditioner further includes:

[0018] When the temperature of the external fresh air is lower than 4° C., the heating disk of the fresh air unit is controlled to heat the fresh air unit to prevent the surface cooler in the fresh air unit from being frozen and cracked.

[0019] The main features of the fresh air air conditioning system are as follows: it includes a fresh air unit, an air conditioning box and a main control component. The main control component is connected to the fresh air unit and the air conditioning box respectively. The air output of the fresh air unit is delivered to the surface cooler of the air conditioning box.

[0020] When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box;

[0021] When the primary return air needs to be dehumidified, the main control component controls the air-conditioning box to perform a dehumidification operation on the primary return air.

[0022] The above-mentioned fresh air air conditioning system, wherein the fresh air air conditioning system further includes:

[0023] A first temperature detection component is used to detect the dew point temperature of the external fresh air;

[0024] The first temperature comparator is respectively connected to the machine dew point temperature of the air-conditioning box and the dew point temperature of the outside fresh air detected by the first temperature detection component, and transmits the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air-conditioning box to the main control component to determine whether to drive the main control component to control the fresh air unit to perform dehumidification operation on the fresh air based on the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air-conditioning box.

[0025] The above-mentioned fresh air air conditioning system, wherein the first temperature detection component is also used to detect the temperature of the external fresh air, and the fresh air air conditioning system further includes:

[0026] The second temperature comparator is respectively connected to the temperature of the outside fresh air and the supply air temperature of the air-conditioning box, and transmits the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box to the main control component. The main control component is connected to the surface cooler in the fresh air unit to adjust the outlet air temperature of the fresh air unit and control the start and stop of the surface cooler in the fresh air unit according to the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box.

[0027] The above-mentioned fresh air air conditioning system, wherein the fresh air unit also includes:

[0028] A heating disk is connected to the first temperature detection component and the main control component respectively. The heating disk is used to heat the fresh air unit through the heating disk when the temperature of the external fresh air is lower than 4°C.

[0029] Beneficial effects of the control method for fresh air air conditioning and the fresh air air conditioning system of the present invention:

[0030] The control method and fresh air air conditioning system of the fresh air air conditioner are adopted to control the fresh air unit to dehumidify the external fresh air, control the air-conditioning box to dehumidify the primary return air, and deliver the outlet air of the fresh air unit to the surface cooler of the air-conditioning box. Since the dehumidification mode of the fresh air unit and the air-conditioning box in the fresh air air conditioner is single-point control, the temperature and humidity control of the fresh air unit and the air-conditioning box are independent. After the fresh air processed by the fresh air unit is delivered to the surface cooler of the air-conditioning box, such structural design and control method can reflect the best energy-saving effect regardless of whether the fresh air needs to be dehumidified, effectively improve the energy saving performance, and have a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention.

[0032] Figure 1 It is a schematic diagram of the connection structure between the fresh air unit and the air conditioning box in the fresh air air conditioning system.

[0033] Figure 2 It is a control logic diagram of the fresh air unit in the control method of the fresh air air conditioner.

[0034] Reference numerals

[0035] 1 Fresh air unit

[0036] 11. Fresh air unit primary filter

[0037] 12 Fresh air unit heat plate

[0038] 13Fresh air unit cold plate

[0039] 14 Fresh air unit water baffle

[0040] 15Fresh air unit fan

[0041] 16 Medium efficiency filter of fresh air unit

[0042] 2 air conditioning box

[0043] 21 Primary return air point

[0044] 22 air conditioning box cold plate

[0045] 23 air conditioning box water baffle

[0046] 24 air conditioning box fan

[0047] 25 air conditioning box heat plate

[0048] 26 Air conditioning box humidifier

[0049] 27 air conditioning box medium efficiency filter

[0050] 28 Secondary return air point

[0051] 29 air outlet

[0052] 3 Fresh air DETAILED DESCRIPTION

[0053] In order to make the technical means, creative features, objectives and effects of the invention easier to understand, the invention is further described below with reference to specific diagrams. However, the invention is not limited to the following implementation cases.

[0054] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0055] The fresh air air conditioning system in this embodiment includes a fresh air unit, an air conditioning box and a main control component. The main control component is connected to the fresh air unit and the air conditioning box respectively. The air output of the fresh air unit is delivered to the surface cooler of the air conditioning box.

[0056] When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box;

[0057] When the primary return air needs to be dehumidified, the main control component controls the air-conditioning box to perform a dehumidification operation on the primary return air.

[0058] This structure allows the fresh air processed by the fresh air unit (MAU, Make-up Air Unit, an air conditioning equipment that provides fresh air) to be directly sent to the surface cooler of the air-conditioning box (AHU, Air Handle Unit). It is not directly mixed with the primary return air of the air-conditioning box, but is mixed with the secondary return air of the air-conditioning box (if there is a secondary return air), and the primary return air of the air-conditioning box returns before the surface cooler.

[0059] Among them, the side of the air conditioner close to the air inlet is called the front of the air conditioner, and the side close to the air outlet is called the back of the air conditioner.

[0060] When there is a need for fresh air dehumidification or primary return air dehumidification:

[0061] The fresh air unit is used to dehumidify the fresh air; the air-conditioning box is used to dehumidify the return air. The wet load of the return air includes the inherent wet load generated by the clean area and the wet load generated when cleaning the clean area. The air-conditioning box does not need to consider the wet load of the external fresh air treatment.

[0062] This design can achieve the best energy-saving effect regardless of whether the external fresh air needs to be dehumidified.

[0063] In this embodiment, the fresh air air conditioning system further includes:

[0064] A first temperature detection component is used to detect the dew point temperature of the external fresh air;

[0065] The first temperature comparator is respectively connected to the machine dew point temperature of the air-conditioning box and the dew point temperature of the outside fresh air detected by the first temperature detection component, and transmits the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air-conditioning box to the main control component to determine whether to drive the main control component to control the fresh air unit to perform dehumidification operation on the fresh air based on the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air-conditioning box.

[0066] When the dew point temperature of the outside fresh air is higher than the machine dew point temperature of the air conditioning box, it is necessary to perform a dehumidification operation on the fresh air.

[0067] In this embodiment, the first temperature detection component is further used to detect the temperature of the external fresh air, and the fresh air air conditioning system further includes:

[0068] The second temperature comparator is respectively connected to the temperature of the outside fresh air and the supply air temperature of the air-conditioning box, and transmits the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box to the main control component. The main control component is connected to the surface cooler in the fresh air unit to adjust the outlet air temperature of the fresh air unit and control the start and stop of the surface cooler in the fresh air unit according to the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box.

[0069] That is, if the dew point of the outside fresh air is lower than the dew point of all AC units, the fresh air unit does not need to perform a dehumidification cycle; only its outlet air temperature needs to be adjusted. If the fresh air unit does not require dehumidification, but the dry-bulb temperature of the outside fresh air is higher than the AC unit's supply air temperature, the fresh air unit must cool the fresh air down to a dry-bulb temperature 1-2°C lower than the AC unit's supply air temperature. This temperature setting effectively accounts for the heat generated by the AC unit's fan and the heat load of the secondary return air, preventing the terminal outlet air temperature of the fresh air unit from being too high. If the dry-bulb temperature of the outside fresh air is already 1-2°C lower than the AC unit's supply air temperature, even if the fresh air unit does not require dehumidification, it is necessary to determine whether the outside fresh air temperature is close to 4°C. If so, the fresh air unit must perform a temperature increase to prevent the air from approaching 4°C and prevent the fresh air unit's surface cooler from freezing. If the temperature is not close to 4℃ at this time, the fresh air unit only needs to run the fan, and there is no need to adjust the cooling and heating loads, and the surface cooler of the fresh air unit can be turned off.

[0070] The fresh air unit in this embodiment is responsible for processing the wet load of the external fresh air and adjusting the temperature of the fresh air. When the dew point temperature of the external fresh air reaches the machine dew point temperature of the air-conditioning box, it is determined that the fresh air needs to be dehumidified. When the temperature adjustment function is executed, the output fresh air temperature needs to be controlled at 1 to 2°C lower than the supply air temperature of the air-conditioning box.

[0071] In this embodiment, the fresh air unit further includes:

[0072] A heating disk is connected to the first temperature detection component and the main control component respectively. The heating disk is used to heat the fresh air unit through the heating disk when the temperature of the external fresh air is lower than 4°C.

[0073] The main control component in the above embodiment can be composed of a PLC control system, the first temperature comparator and the second temperature comparator can also be composed of a PLC control system, and the first temperature detection component can be composed of a temperature probe connected to the PLC control system. When in use, the PLC control system collects detection data of the external fresh air, and determines whether it is necessary to perform a dehumidification operation on the external fresh air based on the control standard set by the fresh air unit. If the dew point temperature of the external fresh air is greater than the machine dew point temperature of the air-conditioning box, the fresh air unit executes a dehumidification program, controls its outlet air temperature to reach the machine dew point temperature of the air-conditioning box, and sends it to the surface cooler of the air-conditioning box, that is, when the air-conditioning box includes a water baffle, the outlet air of the fresh air unit is sent to the downstream of the water baffle.

[0074] In this embodiment, if the primary return air of the AC unit requires dehumidification, which is primarily due to the inherent heat and humidity load within the clean area (such as the heat and humidity load generated by the operation of equipment within the clean area) or the humidity load generated by water used for cleaning and sanitation within the area, the AC unit's surface cooler will need to be activated in dehumidification mode. The air outlet temperature of the surface cooler can be controlled to the machine dew point temperature of the AC unit to implement primary return air dehumidification.

[0075] like Figure 1 As shown, in the fresh air air conditioning system of this embodiment, the fresh air unit 1 is provided with a fresh air unit primary filter 11, a fresh air unit hot plate 12, a fresh air unit cold plate 13, a fresh air unit water baffle 14, a fresh air unit fan 15 and a fresh air unit medium efficiency filter 16 in sequence along the fresh air inlet to the fresh air outlet direction, that is, the fresh air 3 from the outside is Figure 1 The fresh air enters the fresh air unit 1 from the leftmost direction, and the air-conditioning box 2 is provided with an air-conditioning box cold plate 22, an air-conditioning box water baffle 23, an air-conditioning box fan 24, an air-conditioning box hot plate 25, an air-conditioning box humidifier 26 and an air-conditioning box medium efficiency filter 27 in sequence along the primary return air point 21 to the air supply outlet 29. The secondary return air point 28 is located between the air-conditioning box water baffle 23 and the air-conditioning box fan 24. The fresh air output by the fresh air unit is transported to the surface cooler of the air-conditioning box, that is, behind the air-conditioning box water baffle 23 of the air-conditioning box.

[0076] The fresh air air conditioning system in the above embodiment can be used to execute the following fresh air air conditioning control method, which includes:

[0077] When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box;

[0078] Among them, when it is detected that the dew point temperature of the external fresh air is greater than or equal to the machine dew point temperature of the air-conditioning box, it is determined that the external fresh air needs to be dehumidified; when it is detected that the dew point temperature of the external fresh air is less than the machine dew point temperature of the air-conditioning box, it is determined that the external fresh air does not need to be dehumidified. Among them, when multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

[0079] When the main control component controls the fresh air unit to perform dehumidification operation on the fresh air, the air outlet temperature of the fresh air unit is the machine dew point temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

[0080] When the outside fresh air does not need to be dehumidified, the temperature of the outside fresh air is compared with the supply air temperature of the air conditioning box;

[0081] If the temperature of the external fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled to be below the supply air temperature of the air-conditioning box. Specifically, if the temperature of the external fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled to be within a temperature range that is 1 to 2°C lower than the supply air temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the supply air temperature of the air-conditioning box is the supply air temperature of the air-conditioning box with the lowest supply air temperature among the air-conditioning boxes. If the temperature of the external fresh air is lower than the supply air temperature of the air-conditioning box, the surface cooler of the fresh air unit is controlled to stop working, and only the fan of the fresh air unit is controlled to continue running.

[0082] When the temperature of the external fresh air is lower than 4° C., the heating disk of the fresh air unit is controlled to heat the fresh air unit to prevent the surface cooler in the fresh air unit from being frozen and cracked.

[0083] When the primary return air needs to be dehumidified, the main control component controls the air-conditioning box to perform a dehumidification operation on the primary return air.

[0084] The above-mentioned control method of fresh air air conditioning and fresh air air conditioning system send the fresh air processed by the fresh air unit directly to the surface cooler of the air-conditioning box, and respectively control the fresh air unit and the air-conditioning box to perform fresh air dehumidification and primary return air dehumidification, thereby achieving the best energy-saving effect regardless of whether the fresh air needs to be dehumidified, and effectively achieving the purpose of energy saving and emission reduction.

[0085] The following combination Figure 2 The operation process of the fresh air unit in the fresh air air conditioning system is further explained:

[0086] like Figure 2 As shown, when the system is running, the dew point temperature of the fresh air outside is first detected, and the detected dew point temperature is compared with the machine dew point temperature of the air conditioning box;

[0087] When the PLC system detects that the dew point temperature of the fresh air is greater than or equal to the dew point temperature of the air conditioner, the fresh air unit will execute the dehumidification process. The outlet air temperature is controlled to reach the dew point temperature of the air conditioner and sent to the surface cooler of the air conditioner, which is actually downstream of the water baffle.

[0088] If the PLC system finds that the dew point temperature of the outside fresh air is lower than the dew point temperature of the air conditioning box, the fresh air unit does not need to perform the dehumidification process, and only needs to adjust its outlet air temperature.

[0089] When the fresh air unit does not need dehumidification, but the dry bulb temperature of the outside fresh air is higher than the supply air temperature of the air-conditioning box, the fresh air unit also needs to cool the fresh air so that its dry bulb temperature is 1 to 2°C lower than the supply air temperature of the air-conditioning box. This setting is mainly based on the heating of the fan of the air-conditioning box and the heat load of the secondary return air.

[0090] If the dry-bulb temperature of the outside fresh air is already 1-2°C lower than the supply air temperature of the air conditioner when the fresh air unit does not require dehumidification, it is necessary to determine whether the outside fresh air temperature is close to 4°C. If so, the fresh air unit needs to perform a temperature increase procedure to break the trend of approaching 4°C to ensure that the surface cooler of the fresh air unit does not freeze. If it is not close to 4°C, the fresh air unit only needs to run the fan and does not need to adjust the cooling and heating loads.

[0091] If the air conditioner's primary return air needs dehumidification, this is likely due to heat and humidity loads within the system or water use for cleaning and sanitation within the area. The air conditioner's surface cooler should then be dehumidified, controlling its outlet air temperature to its dew point. The air conditioner can be controlled using either supply or return air parameters. When using supply air parameters, a dew point monitoring point should be set at the primary return air to determine in advance whether the air conditioner requires dehumidification.

[0092] The control method and fresh air air conditioning system of the fresh air air conditioner are adopted to control the fresh air unit to dehumidify the external fresh air, control the air-conditioning box to dehumidify the primary return air, and deliver the outlet air of the fresh air unit to the surface cooler of the air-conditioning box. Since the dehumidification mode of the fresh air unit and the air-conditioning box in the fresh air air conditioner is single-point control, the temperature and humidity control of the fresh air unit and the air-conditioning box are independent. After the fresh air processed by the fresh air unit is delivered to the surface cooler of the air-conditioning box, such structural design and control method can reflect the best energy-saving effect regardless of whether the fresh air needs to be dehumidified, effectively improve the energy saving performance, and have a wide range of applications.

[0093] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A control method for a fresh air air conditioner, characterized in that: Applied to a fresh air air conditioning system, the fresh air air conditioning system includes a fresh air unit, an air conditioning box and a main control component, the main control component is connected to the fresh air unit and the air conditioning box respectively, the air output of the fresh air unit is delivered to the surface cooler of the air conditioning box; the control method of the fresh air air conditioning includes: When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box; When the primary return air needs to be dehumidified, the main control component controls the air conditioning box to perform a dehumidification operation on the primary return air; When it is detected that the dew point temperature of the outside fresh air is greater than or equal to the machine dew point temperature of the air-conditioning box, it is determined that the outside fresh air needs to be dehumidified; when it is detected that the dew point temperature of the outside fresh air is less than the machine dew point temperature of the air-conditioning box, it is determined that the outside fresh air does not need to be dehumidified, wherein, when multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes; When the main control component controls the fresh air unit to perform dehumidification operation on the fresh air, the air outlet temperature of the fresh air unit is the machine dew point temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

2. The control method of the fresh air air conditioner according to claim 1, characterized in that: The control method of the fresh air air conditioner further includes: When the outside fresh air does not need to be dehumidified, the temperature of the outside fresh air is compared with the supply air temperature of the air conditioning box; If the temperature of the outside fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled to be below the supply air temperature of the air-conditioning box; if the temperature of the outside fresh air is lower than the supply air temperature of the air-conditioning box, the surface cooler of the fresh air unit is controlled to stop working, and only the fan of the fresh air unit is controlled to continue running.

3. The control method of the fresh air air conditioner according to claim 2, characterized in that: If the temperature of the outside fresh air is greater than or equal to the supply air temperature of the air conditioning box, the outlet air temperature of the fresh air unit is controlled to be lower than the supply air temperature of the air conditioning box, specifically: If the temperature of the external fresh air is greater than or equal to the supply air temperature of the air-conditioning box, the outlet air temperature of the fresh air unit is controlled within a temperature range of 1 to 2°C lower than the supply air temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the supply air temperature of the air-conditioning box is the supply air temperature of the air-conditioning box with the lowest supply air temperature among the air-conditioning boxes.

4. The control method of the fresh air air conditioner according to claim 1, characterized in that: The control method of the fresh air air conditioner further includes: When the temperature of the external fresh air is lower than 4° C., the heating disk of the fresh air unit is controlled to heat the fresh air unit to prevent the surface cooler in the fresh air unit from being frozen and cracked.

5. A fresh air air conditioning system, characterized in that: It includes a fresh air unit, an air conditioning box and a main control component. The main control component is connected to the fresh air unit and the air conditioning box respectively. The air output of the fresh air unit is transported to the surface cooler of the air conditioning box. When the outside fresh air needs to be dehumidified, the main control component controls the fresh air unit to perform a dehumidification operation on the fresh air, and delivers the dehumidified fresh air to the surface cooler of the air conditioning box; When the primary return air needs to be dehumidified, the main control component controls the air conditioning box to perform a dehumidification operation on the primary return air; The fresh air air conditioning system also includes: A first temperature detection component is used to detect the dew point temperature of the external fresh air; a first temperature comparator, connected to the machine dew point temperature of the air conditioning box and the dew point temperature of the outside fresh air detected by the first temperature detection component, respectively, and transmitting the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air conditioning box to the main control component, so as to determine whether to drive the main control component to control the fresh air unit to perform a dehumidification operation on the fresh air according to the comparison result of the dew point temperature of the outside fresh air and the machine dew point temperature of the air conditioning box; When the main control component controls the fresh air unit to perform dehumidification operation on the fresh air, the air outlet temperature of the fresh air unit is the machine dew point temperature of the air-conditioning box. When multiple air-conditioning boxes are included, the machine dew point temperature of the air-conditioning box is the machine dew point temperature of the air-conditioning box with the lowest machine dew point temperature among the air-conditioning boxes.

6. The fresh air air conditioning system according to claim 5, characterized in that: The first temperature detection component is further used to detect the temperature of the external fresh air, and the fresh air air conditioning system further includes: The second temperature comparator is respectively connected to the temperature of the outside fresh air and the supply air temperature of the air-conditioning box, and transmits the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box to the main control component. The main control component is connected to the surface cooler in the fresh air unit to adjust the outlet air temperature of the fresh air unit and control the start and stop of the surface cooler in the fresh air unit according to the comparison result of the temperature of the outside fresh air and the supply air temperature of the air-conditioning box.

7. The fresh air air conditioning system according to claim 6, characterized in that: The fresh air unit also includes: A heating disk is connected to the first temperature detection component and the main control component respectively. The heating disk is used to heat the fresh air unit through the heating disk when the temperature of the external fresh air is lower than 4°C.

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