Vertical fresh air handling unit and operation control method thereof

Abstract

The invention provides a vertical fresh air handling unit and an operation control method thereof.The fresh air handling unit comprises a unit body, a surface air cooler and a draught fan are sequentially arranged in the unit body in the height direction, and the surface air cooler can heat or cool air passing through the surface air cooler; the fan is used for sucking outdoor air into the unit main body through the air inlet and discharging the outdoor air from the air supply outlet; the number of the air inlets is multiple, the air inlets are formed in the upstream portion and the downstream portion of the surface air cooler, and each air inlet is provided with a filter and an air valve used for controlling on-off of airflow at the corresponding air inlet. The fresh air handling unit is of a vertical structure, the installation occupied area of the fresh air handling unit is reduced, and the fresh air handling unit can be suitable for more application scenes, especially places with limited length; and air valves of different air inlets are opened and closed according to different outdoor fresh air treatment requirements, so that air entering the unit main body passes through or bypasses the surface air cooler, multi-channel change is realized to change the internal resistance of the unit main body, and the energy consumption of a fan is saved.

Description

Technical Field

[0001] The present invention belongs to the field of air treatment, and in particular relates to a vertical fresh air unit and an operation control method thereof. Background Art

[0002] Fresh air units can provide fresh air indoors, effectively regulating indoor air quality and ensuring breathing safety and thermal comfort for indoor occupants. They do this by filtering, cooling, heating, humidifying and dehumidifying outdoor air before delivering it indoors. Their internal components typically include a filtration section, a cooling and heating section, and a humidification section. However, during transitional seasons, when the outdoor air temperature and humidity are more suitable, fresh air can be introduced directly into the room without undergoing heat and humidity treatment. However, existing conventional fresh air units require the fresh air to flow through a surface cooler during the air treatment process, resulting in high internal resistance within the unit, a high pressure head required by the system, and the fan operating at high power for extended periods, resulting in high overall energy consumption.

[0003] To address the aforementioned technical issues, CN201220020284.7 discloses a bypass-type intelligent energy-saving fresh air unit. This unit features a second air inlet on the side wall between the surface cooler and the fan. This second inlet can be switched to bypass the surface cooler, allowing fresh air to be directly fed into the air supply duct through the fan, reducing system resistance and saving energy. However, the fresh air unit in the aforementioned patent is horizontal, occupying a large area and limiting its application scenarios. Summary of the Invention

[0004] The present invention aims to solve the technical problems existing in the prior art. The first purpose of the present invention is to provide a vertical fresh air unit. The second purpose of the present invention is to provide an operation control method of the vertical fresh air unit based on the present application.

[0005] In order to achieve the first purpose mentioned above, the present invention adopts the following technical solution: a vertical fresh air unit, including a unit body with an air inlet and an air outlet, and a surface cooler and a fan are arranged in sequence inside the unit body along the height direction. The surface cooler can heat or cool the air passing through it, and the fan is used to suck outdoor air into the unit body through the air inlet and discharge it from the air supply port; there are multiple air inlets, and air inlets are provided upstream and downstream of the surface cooler, and each air inlet is provided with a filter and a wind valve for controlling the air flow at the air inlet.

[0006] In the above technical solution, the surface cooler and the fan are arranged at intervals along the height direction inside the unit body, and the fresh air unit is a vertical structure, which reduces the installation area of the fresh air unit and can be applied to more application scenarios, especially places with limited length. Compared with the horizontal structure, the vertical structure of this application provides an additional option; and according to different outdoor fresh air treatment requirements, the air valves of different air inlets are switched on and off to allow the air entering the unit body to pass through or bypass the surface cooler, realizing multi-channel changes to change the internal resistance of the unit body, thereby achieving the effect of saving fan energy consumption.

[0007] In a preferred embodiment of the present invention, multiple air inlets are located on the same side outside the unit body and are spaced apart along the height direction of the unit body; and / or the air outlet is located at the top of the unit body, and the surface cooler and the fan are arranged in sequence from bottom to top.

[0008] The above technical solution places the air inlet, filter and air valve outside the unit body, optimizes the internal structural space of the unit body, and minimizes the volume and footprint of the fresh air unit; the air outlet is set at the top, and the air flows from bottom to top in the unit body, which is more conducive to connection with the air supply duct than setting the air outlet at the bottom.

[0009] In another preferred embodiment of the present invention, there are two surface coolers, which are a first surface cooler and a second surface cooler spaced apart in the height direction, and air inlets are provided upstream of the first surface cooler, upstream of the second surface cooler, and downstream of the second surface cooler.

[0010] The above technical solution divides the surface cooler into two. When cooling, dehumidifying and heating the air, the second surface cooler will work first. Only when the second surface cooler cannot meet the requirements, the first and second surface coolers will work at the same time. When only the second surface cooler is working, the air can bypass the first surface cooler, further reducing the internal resistance of the unit body and further reducing the energy consumption of the fan. Moreover, dividing the surface cooler into two also reduces the working time of the first surface cooler and extends its service life.

[0011] In another preferred embodiment of the present invention, the surface cooler is connected to a water circulation pipeline, and cold water is passed into the surface cooler through the water circulation pipeline to cool and dehumidify the air flowing through it, and hot water is passed into the surface cooler through the water circulation pipeline to heat and increase the temperature of the air flowing through it.

[0012] The above technical solution introduces cold water / hot water into the surface cooler through the water circulation pipeline to exchange heat with the air to reduce / increase the fresh air temperature. It has a simple structure, the circulating water can be reused, and it is energy-saving and environmentally friendly.

[0013] In another preferred embodiment of the present invention, a reheater located between the second cooler and the fan is further provided inside the unit body along the height direction, and an air inlet is also provided upstream of the reheater downstream of the second cooler; the air inlet provided upstream of the first cooler is a first air inlet, and the air valve at the first air inlet is a first air valve; the air inlet provided downstream of the first cooler and upstream of the second cooler is a second air inlet, and the air valve at the second air inlet is a second air valve; the air inlet provided downstream of the second cooler is a third air inlet, and the air valve at the third air inlet is a third air valve.

[0014] In the above technical solution, when the temperature of the air after cooling and dehumidification by the surface cooler is too low, it can be heated by the reheater to increase the air temperature.

[0015] In another preferred embodiment of the present invention, the reheater is connected to a water circulation pipeline, and hot water is introduced into the reheater through the water circulation pipeline to heat and increase the temperature of the air flowing through the reheater.

[0016] The above technical solution introduces hot water into the reheater through a water circulation pipeline to exchange heat with the air to increase the air temperature. It has a simple structure, and the circulating water can be reused, which is energy-saving and environmentally friendly.

[0017] In another preferred embodiment of the present invention, the fresh air unit also includes an outdoor temperature and humidity sensor for measuring the outdoor air temperature and humidity, and a supply air temperature and humidity sensor for measuring the temperature and humidity of the air supplied to the room. The signal output ends of the outdoor temperature and humidity sensor and the supply air temperature and humidity sensor are connected to the input end of the controller, and the control output end of the controller is connected to the enable end of each air valve, surface cooler and reheater.

[0018] The above technical solution facilitates real-time monitoring of the temperature and humidity of indoor and outdoor air by setting up outdoor temperature and humidity sensors and supply air temperature and humidity sensors 4. Moreover, the controller can also adjust the opening and closing of each air valve, surface cooler and reheater according to the temperature and humidity of the outdoor air to make the supply air temperature and supply air humidity of the fresh air sent into the room appropriate.

[0019] To achieve the second objective, the present invention employs the following technical solution: a method for controlling the operation of a vertical fresh air unit, wherein an outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits the information to a controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater based on the outdoor air temperature Tw and humidity dw to ensure that the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor are appropriate. The specific process is as follows:

[0020] When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first and second air valves are closed, and the third air valve is opened. Outdoor fresh air enters through the third air inlet, and the fresh air unit operates in ventilation mode;

[0021] When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1, dw1≤dw≤dw2, the first air valve and the third air valve are closed, and the second air valve is opened. Outdoor fresh air enters through the second air inlet, and hot water is introduced into the second surface cooler. The fresh air unit operates in heating mode. The controller first regulates the hot water flow of the second surface cooler according to the supply air temperature Ts: when the supply air temperature Ts1≤Ts≤Ts2, the hot water flow of the second surface cooler is kept unchanged; when Ts<Ts1, the hot water flow of the second surface cooler is increased; when Ts>Ts2, the hot water flow of the second surface cooler is reduced; when the second surface cooler reaches the maximum hot water flow, it is still Ts<Ts1, the second air valve and the third air valve are closed, and the first air valve is opened. Outdoor fresh air enters through the first air inlet, and hot water is introduced into both the first and second surface coolers. The second surface cooler maintains the maximum hot water flow, and the controller adjusts the supply air temperature by adjusting the hot water flow of the first surface cooler.

[0022] When the outdoor air temperature Tw is appropriate and the humidity dw is too high, that is, Tw1<Tw≤Tw2, dw>dw2, close the first air valve and the third air valve, open the second air valve, and outdoor fresh air enters through the second air inlet. Cold water is introduced into the second surface cooler. The fresh air unit operates in dehumidification mode. The air entering the main body of the unit is cooled and dehumidified by the second surface cooler and then sent into the room. When the supply air humidity ds1<ds<ds2, keep the cold water flow of the second surface cooler unchanged; when the supply air humidity ds<ds1, reduce the cold water flow of the second surface cooler; when the supply air humidity ds>ds2, Increase the cold water flow rate of the second surface cooler; when the second surface cooler reaches the maximum cold water flow rate, and ds is still greater than ds2, close the second and third air valves, open the first air valve, and allow outdoor fresh air to enter through the first air inlet. Cold water is then introduced into both the first and second surface coolers, and the second surface cooler maintains the maximum cold water flow rate. The controller adjusts the supply air humidity ds by adjusting the cold water flow rate of the first surface cooler. The controller then determines whether to open the reheater based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, open the reheater and introduce hot water into it.

[0023] When the outdoor air temperature Tw is too high and the humidity dw is too large, that is, Tw>Tw2, dw>dw2, close the first air valve and the third air valve, open the second air valve, and outdoor fresh air enters through the second air inlet. Cold water is introduced into the second surface cooler, and the fresh air unit operates in cooling mode; the controller adjusts the cold water flow of the second surface cooler according to the supply air temperature Ts and the supply air humidity ds: when the supply air temperature Ts1≤Ts≤Ts2 and the supply air humidity ds1<ds<ds2, keep the cold water flow of the second surface cooler unchanged; when Ts>Ts2 or ds>ds2, increase the cold water flow of the second surface cooler; when Ts<Ts1 and ds When s is less than ds1, the cold water flow of the second cooler is reduced; when the second cooler reaches the maximum cold water flow, Ts>Ts2 or ds>ds2, the second air valve and the third air valve are closed, and the first air valve is opened. Outdoor fresh air enters through the first air inlet, and cold water is passed into the first and second coolers. The second cooler maintains the maximum cold water flow. The controller adjusts the supply air humidity ds by adjusting the cold water flow of the first cooler, and then determines whether the reheater is turned on according to the supply air temperature TsTs: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater and pass hot water into it. To achieve the second objective, the present invention may also employ the following technical solution: a method for controlling the operation of a vertical fresh air unit, wherein the unit body is further provided with a return air inlet located downstream of a second surface cooler, the return air inlet being used to introduce indoor air into the unit body, the return air inlet being provided with a fourth air valve, the first air valve, the second air valve, the third air valve, and the fourth air valve being variable air volume valves capable of adjusting air volume;

[0024] The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows:

[0025] When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first air valve, the second air valve and the fourth air valve are closed, the third air valve is opened, and outdoor fresh air enters through the third air inlet. The fresh air unit operates in ventilation mode;

[0026] When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1,dw1≤dw≤dw2, the fresh air unit operates in heating mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity, and then calculates the heat Qh required to process the fresh air to the air state point corresponding to the enthalpy h1 at Tw1,dw based on the user-set fresh air volume Ws. Qh=(h1-hw)*Ws;

[0027] If the calculated required heat Qh is greater than the rated heat capacity Qr of the second surface cooler, the supply air parameters are first adjusted by return air. The amount of outdoor fresh air that the second surface cooler can handle to the air state point Tw1,dw at the rated heat capacity Qr is calculated. Assuming that the fresh air volume that can be handled is set to W1 and the indoor return air volume is set to W2, W1 = Qr / (h1-hw), W2 = Ws-W1, then the ratio of the fresh air volume to the total supply air volume k1 is: k1 = W1 / Ws, and the ratio of the return air volume to the total supply air volume k2 is: k2 = W2 / Ws;

[0028] When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. The supply air parameters are adjusted by return air, the second air valve and the fourth air valve are opened, the first air valve and the third air valve are closed, the air volume of the second air valve is adjusted to W1, the air volume of the fourth air valve is adjusted to W2, and the second surface cooler maintains the maximum hot water flow, so as to meet the supply air parameter requirements; when K2>Kmax, the supply air parameters are not adjusted by return air, at this time the first air valve is opened, the second air valve, the third air valve and the fourth air valve are closed, hot water is passed into the first surface cooler and the second surface cooler, the second surface cooler maintains the maximum hot water flow, and the supply air temperature Ts is controlled by adjusting the hot water flow of the first surface cooler;

[0029] If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler, the second air valve is opened, the first air valve, the third air valve and the fourth air valve are closed, hot water is introduced into the second surface cooler, and the supply air temperature Ts is controlled by adjusting the hot water flow of the second surface cooler;

[0030] When the outdoor air temperature Tw is too high or the humidity dw is too high, that is, Tw>Tw2 or dw>dw2, the fresh air unit operates in cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity, and then calculates the cooling capacity Qc required for the fresh air to be processed to the cooling and dehumidification state point L1 corresponding to the air enthalpy h2 based on the user-set fresh air volume Ws. Qc=(hw-h2)*Ws;

[0031] If the required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler, the supply air parameters are first adjusted by return air to calculate how much outdoor fresh air the second surface cooler can handle to the cooling and dehumidification state point L1 at the rated cooling capacity Ql. Assuming that the fresh air volume that can be handled is set to W3 and the indoor return air volume is set to W4, W3 = Ql / (hw-h2), W4 = Ws-W3, then the ratio of the fresh air volume to the total supply air volume k3 is: k3 = W3 / Ws, and the ratio of the return air volume to the total supply air volume K4 is: k4 = W4 / Ws;

[0032] When k4≤Kmax, the supply air parameters are adjusted by returning air, the second air valve and the fourth air valve are opened, the first air valve and the third air valve are closed, the air volume of the second air valve is adjusted to W3, the air volume of the fourth air valve is adjusted to W4, and the second surface cooler maintains the maximum cold water flow, so as to meet the supply air parameter requirements; when K4>Kmax, the supply air parameters are not adjusted by returning air, at this time the first air valve is opened, the second air valve, the third air valve and the fourth air valve are closed, cold water is passed into the first surface cooler and the second surface cooler, the second surface cooler maintains the maximum cold water flow, and the supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler, and then the reheater is judged whether to open according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater is kept closed; when Ts<Ts1, the reheater is opened;

[0033] If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler, the second air valve is opened, the first air valve, the third air valve and the fourth air valve are closed, cold water is introduced into the second surface cooler, and the supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler. Then, whether the reheater is turned on is determined based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater is kept closed; when Ts<Ts1, the reheater is turned on.

[0034] The above technical solution, by setting the return air inlet and the fourth air valve, first calculates the heat / cold capacity required for fresh air processing through the indoor and outdoor air enthalpy values and the user-set fresh air volume when the fresh air unit is heating, cooling, and dehumidifying. When the calculated required heat / cold capacity is greater than the rated cooling capacity of the second surface cooler, the supply air parameters are first adjusted by the return air method (the second surface cooler is also working at this time) to reduce the load of the second surface cooler. When the return air ratio is too large and the supply air parameters cannot be adjusted by the return air method, the two surface coolers are turned on at the same time to reduce the energy consumption of the entire fresh air unit and save energy.

[0035] To achieve the second objective, the present invention may further employ the following technical solution: an operation control method for a vertical fresh air unit, wherein the unit body is further provided with a return air inlet located between the downstream of a first surface cooler and the upstream of a second surface cooler, the return air inlet being used to introduce indoor air into the unit body, a fourth air valve being provided at the return air inlet, the first air valve, the second air valve, the third air valve, and the fourth air valve being variable air volume valves capable of adjusting air volume;

[0036] The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows:

[0037] When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first air valve, the second air valve and the fourth air valve are closed, the third air valve is opened, and outdoor fresh air enters through the third air inlet. The fresh air unit operates in ventilation mode;

[0038] When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1,dw1≤dw≤dw2, the fresh air unit operates in heating mode. The controller first calculates the outdoor air enthalpy hw according to the outdoor temperature and humidity, and then calculates the heat Qh required for the fresh air to be processed to the air state point where Tw1, dw is located, corresponding to the enthalpy h1, according to the user-set fresh air volume Ws. Qh=(h1-hw)*Ws,

[0039] If the calculated required heat Qh is greater than the rated heat capacity Qr of the second surface cooler, the air supply parameters are adjusted first by the return air method. Assuming that the temperature of the indoor return air is Tb, the humidity is db, the corresponding air enthalpy value is hb, the indoor return air volume is W2, and the outdoor fresh air volume is W1, then when the rated heat capacity Qr and the set fresh air volume Ws are used, the second surface cooler can process the mixed air with the maximum air enthalpy value hm at the state point after the fresh air and return air are mixed to the air at Tw1,dm. Gas state point, where dm represents the mixed air humidity after the fresh air and return air are mixed, dm = (dw*W1+db*W2) / (W1+W2), hm = h1-(Qr / Ws), W1 = Ws*((hm-hb) / (hw-hb)), W2 = Ws-W1, then the ratio of the fresh air volume to the total supply air volume k1 is: k1=W1 / Ws, and the ratio of the return air volume to the total supply air volume k2 is: k2=W2 / Ws;

[0040] When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. The second and fourth air valves are opened, and the first and third air valves are closed. The air volume of the second air valve is adjusted to W1, and the air volume of the fourth air valve is adjusted to W2. The second surface cooler maintains the maximum hot water flow rate to meet the supply air parameter requirements. When k2>Kmax, the supply air parameters are not adjusted by return air. At this time, the first air valve is opened and the air volume is set to Ws. The second, third and fourth air valves are closed. Hot water is introduced into the first and second surface coolers. The second surface cooler maintains the maximum hot water flow rate. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the first surface cooler.

[0041] If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler, then open the second air valve and set the air volume to Ws. The first, third, and fourth air valves are closed, and hot water is supplied to the second surface cooler. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the second surface cooler.

[0042] When the outdoor air temperature Tw is too high or the humidity dw is too high, that is, Tw>Tw2 or dw>dw2, the fresh air unit operates in the cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy value hw according to the outdoor temperature and humidity, and then calculates the cooling capacity Qc required for the fresh air to be processed to the cooling and dehumidification state point L2 according to the user-set fresh air volume Ws. Qc=(hw-h2)*Ws. If the calculated required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler, the air supply parameters are first adjusted by return air. Assuming that the temperature of the indoor return air is Tb and the humidity is db, the corresponding The air enthalpy value is hb, the indoor return air volume is W4, and the outdoor fresh air volume is W3. Then, when the single-stage surface cooler has the rated cooling capacity Ql and the set fresh air volume Ws, it can process the mixed air with the maximum air enthalpy value of hm at the state point after the fresh air and return air are mixed to the cooling and dehumidification state point L2. hm=h2+(Ql / Ws), W3=Ws*((hm-hb) / (hw-hb)), W4=Ws-W3, then the ratio of fresh air volume to total supply air volume k3 is: k3=W3 / Ws, and the ratio of return air volume to total supply air volume k4 is: k4=W4 / Ws

[0043] When k4≤Kmax, open the second air valve and the fourth air valve, close the first air valve and the third air valve, adjust the air volume of the second air valve to W3, and the air volume of the fourth air valve to W4, and maintain the maximum cold water flow of the second surface cooler to meet the requirements of the air supply parameters; when k2>Kmax, the air supply parameters are not adjusted by returning the air. At this time, open the first air valve and set the air volume to Ws, and close the second air valve, the third air valve and the fourth air valve. Cold water is passed through the first and second surface coolers, and the second surface cooler maintains the maximum cold water flow. The supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler, and then judge whether the reheater is turned on according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater;

[0044] If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler, open the second air valve and set the air volume to Ws. The first air valve, the third air valve and the fourth air valve are closed. Cold water is introduced into the second surface cooler. The supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler. Then, whether the reheater is turned on is determined based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater.

[0045] The above technical solution provides an implementation method of arranging the return air outlet upstream of the second surface cooler. The difference from arranging the return air outlet downstream of the second surface cooler is that the return air introduced by this solution will be processed through the second surface cooler. When calculating the cooling capacity and heating capacity of the second surface cooler, the air enthalpy value of the mixed state of fresh air and return air is used for calculation, so as to achieve the purpose of accurately controlling the supply air temperature and humidity.

[0046] Compared with the existing technology, the preferred technical solution of the present invention has the following beneficial effects:

[0047] 1) The fresh air unit of the present invention has a vertical structure. By placing the air inlet, filter and air valve outside the unit body, the internal structural space of the unit body is optimized, the volume and floor space of the fresh air unit are minimized, and it can be applied to more application scenarios.

[0048] 2) In response to different outdoor fresh air processing needs, fresh air is allowed to enter from different air inlets by opening and closing different air valves, achieving multi-channel changes to change the internal resistance of the unit body, thereby saving fan energy consumption, reducing fresh air load and energy consumption while ensuring demand.

[0049] 3) The present invention provides a return air port and a fourth air valve to introduce indoor return air into the unit body according to the situation, thereby reducing the situation where two surface coolers are opened at the same time, thereby reducing the internal resistance of the unit, achieving the effect of reducing the energy consumption of the entire fresh air unit and saving energy.

[0050] 4) The present invention sets a return air port and a fourth air valve. When the fresh air unit is heating, cooling, or dehumidifying, the heat / cooling capacity required for fresh air processing is first calculated based on the indoor and outdoor air enthalpy values and the user-set fresh air volume. When the calculated required heat / cooling capacity is greater than the rated cooling capacity of the second surface cooler, the supply air parameters are first adjusted by return air. When the return air ratio is too large and the supply air parameters cannot be adjusted by return air, the two surface coolers are opened at the same time to reduce the energy consumption of the entire fresh air unit and save energy.

[0051] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0053] Figure 1 This is a schematic diagram of the main structure of a vertical fresh air unit in Example 1.

[0054] Figure 2 This is a side structural schematic diagram of a vertical fresh air unit in Example 1.

[0055] Figure 3 This is a side structural diagram of a vertical fresh air unit in Example 2.

[0056] Figure 4 This is a side structural schematic diagram of a vertical fresh air unit in Example 3.

[0057] The figure marks in the drawings of the specification include: unit body 1, air inlet 2, first air inlet 21, second air inlet 22, third air inlet 23, air outlet 3, surface cooler 4, first surface cooler 41, second surface cooler 42, reheater 5, fan 6, filter 7, air valve 8, first air valve 81, second air valve 82, third air valve 83, fourth air valve 84, return air outlet 9. DETAILED DESCRIPTION

[0058] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0059] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "vertical", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0060] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0061] Example 1

[0062] This embodiment provides a vertical fresh air unit and an operation control method thereof.

[0063] like Figure 1As shown in the figure, in a preferred embodiment, the vertical fresh air unit (hereinafter referred to as the fresh air unit) includes a unit body 1 having an air inlet 2 and an air outlet 3. A surface cooler 4 and a fan 6 are sequentially arranged inside the unit body 1 along the height direction. The fan 6 is used to draw outdoor air into the unit body 1 through the air inlet 2 and discharge it from the air outlet. The surface cooler 4 can heat or cool the air passing through it to adjust the temperature of the fresh air. Among them, the number of air inlets 2 is multiple, and air inlets 2 are provided upstream and downstream of the surface cooler 4. Each air inlet 2 is provided with a filter 7 and a damper 8 for controlling the air flow at the air inlet 2. The structure and principle of the filter 7 are existing technologies, such as an air filter with multi-stage filtration.

[0064] The unit body 1 of the present invention adopts a vertical structure, a vertical fresh air unit. Compared with the horizontal structure, the vertical structure reduces the floor space occupied by the installation of the fresh air unit; and by setting multiple air inlets 2, the air valves 8 of different air inlets 2 are selected to be switched. For example, when the outside air temperature is suitable, the fresh air entering the unit body 1 can bypass the surface cooler 4, reducing the internal resistance of the unit body 1, reducing the pressure head required for the system, and saving energy consumption of the fan 6.

[0065] In the present invention, multiple air inlets 2 are located on the same side outside the unit body 1, such as Figure 1 As shown on the left side, multiple air inlets 2 are spaced apart along the height direction of the unit body 1. There is one air outlet 3 located at the top of the unit body 1, and a surface cooler 4 and a fan 6 are arranged in sequence from bottom to top.

[0066] In another preferred embodiment, there are two coolers 4, namely a first cooler 41 and a second cooler 42, spaced apart in the height direction. The first cooler 41 and the second cooler 42 can operate independently, and air inlets 2 are provided upstream of the first cooler 41, upstream of the second cooler 42, and downstream of the second cooler 42. The air inlet 2 provided upstream of the first cooler 41 is a first air inlet 21, and the air valve 8 at the first air inlet 21 is a first air valve 81; the air inlet 2 provided downstream of the first cooler 41 and upstream of the second cooler 42 is a second air inlet 22, and the air valve 8 at the second air inlet 22 is a second air valve 82; the air inlet 2 provided downstream of the second cooler 42 is a third air inlet 23, and the air valve 8 at the third air inlet 23 is a third air valve 83.

[0067] The surface cooler 4 is divided into a first surface cooler 41 and a second surface cooler 42. When cooling, dehumidifying, or heating the air, the second surface cooler 42 works first. Only when the second surface cooler 42 cannot meet the requirements, the first surface cooler 41 and the second surface cooler 42 work simultaneously, which is more energy-efficient.

[0068] In the present invention, the cooler 4 (including the first cooler 41 and the second cooler 42) is connected to a water circulation pipeline. Two water circulation pipelines (not shown) are provided within the unit body 1, one for transporting hot water and the other for transporting cold water. The connection between the cooler 4 and the water circulation pipeline is conventional and will not be described in detail here. Cold water is passed through the water circulation pipeline to the cooler 4 to cool and dehumidify the air passing through it, while hot water is passed through the water circulation pipeline to heat the air passing through it.

[0069] In another preferred embodiment, a reheater 5 is further positioned within the unit body 1, located vertically between the cooler 4 and the fan 6. The reheater 5 is positioned between the second cooler 42 and the fan 6. The third air inlet 23 is positioned between the second cooler 42 and the reheater 5, upstream of the reheater 5. In this embodiment, the reheater 5 is connected to a water circulation line, through which hot water is passed to the reheater 5 to heat the air passing through it. The connection between the reheater 5 and the water circulation line is conventional and will not be described in detail here. If the air temperature after cooling and dehumidification by the cooler 4 is too low, it can be heated by the reheater 5 to raise the air temperature.

[0070] In actual use, the fresh air unit is usually equipped with an outdoor temperature and humidity sensor for measuring the outdoor air temperature and humidity (specifically, it can be installed in the air inlet box or the air inlet duct), and a supply air temperature and humidity sensor for measuring the supply air temperature and humidity of the indoor air (specifically, it can be installed in the air supply box or the air supply duct). The signal output ends of the outdoor temperature and humidity sensor and the supply air temperature and humidity sensor are connected to the input end of the controller, and the control output end of the controller is connected to the enable end of each air valve 8, the surface cooler 4 and the reheater 5 to control the operation of the fresh air unit.

[0071] When the fresh air unit is operating, the controller can control the opening and closing of different air valves 8 corresponding to different seasons and time periods, thereby reducing the internal resistance of the unit body 1 and achieving the effect of saving energy consumption of the fan 6. Specifically, the controller can control the opening and closing of the surface cooler 4 (including the first surface cooler 41 and the second surface cooler 42) and the reheater 5 based on the outdoor air temperature Tw and humidity dw measured by the outdoor temperature and humidity sensor to ensure that the supply air temperature Ts and supply air humidity ds are both appropriate. Specifically, the operation control method of the fresh air unit of the present invention is as follows:

[0072] When the outdoor air temperature Tw and humidity dw both meet indoor comfort requirements (i.e., Tw1 < Tw ≤ Tw2, dw1 ≤ dw ≤ dw2), the first and second condensers 41, 42, and reheater 5 are closed. The first and second air valves 81, 82 are closed, and the third air valve 83 is opened. Outdoor fresh air enters through the third air inlet 23, and the fresh air unit operates in ventilation mode. Fan 6 filters the outdoor fresh air and delivers it directly to the room. Recommended temperatures are: Tw1 = 18°C, Tw2 = 26°C, dw1 = 8 g / kg, and dw2 = 13.8 g / kg.

[0073] When the outdoor air is cold (the outdoor air temperature Tw is too low and the humidity dw is appropriate), that is, Tw≤Tw1, dw1≤dw≤dw2, close the first air valve 81 and the third air valve 83, open the second air valve 82, and allow outdoor fresh air to enter through the second air inlet 22. Hot water is introduced into the second surface cooler 42, and the fresh air unit operates in heating mode. The controller first regulates the hot water flow rate to the second condenser 42 based on the supply air temperature Ts. When the supply air temperature Ts1 ≤ Ts ≤ Ts2, the hot water flow rate to the second condenser 42 remains unchanged. When Ts < Ts1, the hot water flow rate to the second condenser 42 is increased. When Ts > Ts2, the hot water flow rate to the second condenser 42 is reduced. When the second condenser 42 reaches its maximum hot water flow rate, while Ts < Ts1, the second and third air valves 82 and 83 are closed, and the first air valve 81 is opened. Outdoor fresh air enters through the first air inlet 21, and hot water flows into both the first and second condensers 41 and 42. The second condenser 42 maintains its maximum hot water flow rate. The controller adjusts the supply air temperature Ts by adjusting the hot water flow rate to the first condenser 41. Under the action of the fan 6, the outdoor fresh air is filtered, heated, and then delivered to the room. Recommended temperatures are: Ts1 = 18°C, Ts2 = 26°C.

[0074] When the outdoor air is in a warm and humid state (the outdoor air temperature Tw is appropriate and the humidity dw is too high), that is, Tw1<Tw≤Tw2, dw>dw2, close the first air valve 81 and the third air valve 83, open the second air valve 82, and allow outdoor fresh air to enter through the second air inlet 22. Cold water is introduced into the second surface cooler 42, and the fresh air unit operates in dehumidification mode. The air entering the unit body 1 is cooled and dehumidified by the second surface cooler 42 and then sent into the room. When the supply air humidity ds1 < ds < ds2, the cold water flow rate to the second condenser 42 remains unchanged. When the supply air humidity ds < ds1, the cold water flow rate to the second condenser 42 is reduced. When the supply air humidity ds > ds2, the cold water flow rate to the second condenser 42 is increased. When the second condenser 42 reaches its maximum cold water flow rate, and ds still exceeds ds2, the second and third air valves 82 and 83 are closed, and the first air valve 81 is opened. Outdoor fresh air enters through the first air inlet 21, and cold water flows into both the first and second condensers 41 and 42. The second condenser 42 maintains its maximum cold water flow rate. The controller adjusts the supply air humidity ds by adjusting the cold water flow rate to the first condenser 41. The controller then determines whether to open the reheater 5 based on the supply air temperature Ts. When Ts1 ≤ Ts ≤ Ts2, the reheater 5 remains closed. When Ts < Ts1, the reheater 5 is opened and hot water is introduced to increase the supply air temperature. It is recommended that: ds1=8g / kg, ds2=13.8g / kg.

[0075] When the outdoor air is in a high-temperature, hot and humid state (the outdoor air temperature Tw is too high and the humidity dw is too large), that is, Tw>Tw2, dw>dw2, close the first air valve 81 and the third air valve 83, open the second air valve 82, and allow outdoor fresh air to enter through the second air inlet 22. Cold water is introduced into the second surface cooler 42, and the fresh air unit operates in cooling mode. The controller regulates the cold water flow of the second surface cooler 42 according to the supply air temperature Ts and the supply air humidity ds: when the supply air temperature Ts1≤Ts≤Ts2 and the supply air humidity ds1<ds<ds2, the cold water flow of the second surface cooler 42 is kept unchanged; when Ts>Ts2 or ds>ds2, the cold water flow of the second surface cooler 42 is increased; when Ts<Ts1 and ds<ds1, the cold water flow of the second surface cooler 42 is reduced; when the second surface cooler 42 reaches the maximum cold water flow, still Ts>Ts2 or ds>ds2, the second air valve 82 and the third air valve 83 are closed, the first air valve 81 is opened, and outdoor fresh air enters through the first air inlet 21, and cold water is introduced into both the first surface cooler 41 and the second surface cooler 42. The second surface cooler 42 maintains the maximum cold water flow, and the controller adjusts the supply air humidity ds by adjusting the cold water flow of the first surface cooler 41. The controller then determines whether the reheater 5 is turned on based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater 5 is kept closed; when Ts<Ts1, the reheater 5 is turned on, hot water is introduced into it, and the supply air temperature Ts is increased.

[0076] The aforementioned dehumidification mode and cooling mode both dehumidify while cooling or dehumidify while cooling, which can be collectively referred to as cooling and dehumidification mode. The air humidity is preferentially adjusted by passing cold water into the surface cooler 4 (including the first surface cooler 41 and the second surface cooler 42), and the air temperature will also drop at the same time. After adjusting the air humidity to an appropriate range, check whether the air temperature is too low. If the air temperature is too low, it is necessary to heat the air by passing hot water into the reheater 5.

[0077] Example 2

[0078] The structure and principle of this embodiment are basically the same as those of the first embodiment, except that Figure 3 As shown, in this embodiment, the unit body 1 is further provided with a return air inlet 9 located downstream of the second surface cooler 42 and upstream of the reheater 5. The return air inlet 9 is used to introduce indoor air into the unit body 1. A fourth air valve 84 is provided at the return air inlet 9. For example, the return air inlet 9 is located near the third air inlet 23. The air entering through the return air inlet 9 and the third air inlet 23 passes through the same filter 7 before entering the unit body 1. The first air valve 81, the second air valve 82, the third air valve 83, and the fourth air valve 84 are all variable air volume valves with adjustable air volume. Specifically, the air volume can be adjusted by adjusting the opening of each air valve 8. This is prior art and will not be described in detail here.

[0079] In this embodiment, a return air port 9 and a fourth air valve 84 are added. The operation control method of the fresh air unit is different from that of the first embodiment, as follows:

[0080] The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve 8, the surface cooler 4, and the reheater 5 according to the temperature Tw and humidity dw of the outdoor air to ensure that the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor are appropriate. The specific process is as follows:

[0081] When the temperature Tw and humidity dw of the outdoor air meet the comfort requirements of indoor personnel, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler 41, the second surface cooler 42 and the reheater 5 are all closed, the first air valve 81, the second air valve 82 and the fourth air valve 84 are closed, and the third air valve 83 is opened. Outdoor fresh air enters through the third air inlet 23, and the fresh air unit operates in ventilation mode.

[0082] It is recommended to take Tw1=18℃, Tw1=26℃, dw1=8g / kg, and dw2=13.8g / kg.

[0083] When the outdoor air temperature Tw is too low and the humidity dw is appropriate (i.e., Tw ≤ Tw1, dw1 ≤ dw ≤ dw2), the fresh air unit must operate in heating mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity. Then, based on the user-set fresh air volume Ws, it calculates the heat Qh required to process the fresh air to the corresponding enthalpy h1 at the air state point Tw1, dw: Qh = (h1 - hw) * Ws.

[0084] If the required heat Qh is greater than the rated heat capacity Qr of the second condenser 42 (the rated heat capacity of the first condenser 41 and the second condenser 42 are equal), the supply air parameters are first adjusted by return air to calculate how much outdoor fresh air the second condenser 42 can handle at the rated heat capacity Qr to the air state point Tw1,dw. Assuming that the fresh air volume that can be handled is W1 and the indoor return air volume is W2,

[0085] W1=Qr / (h1-hw),

[0086] W2=Ws-W1,

[0087] At this time, the ratio of fresh air volume to total air supply volume k1 is: k1=W1 / Ws,

[0088] The ratio of return air volume to total supply air volume k2 is: k2 = W2 / Ws.

[0089] When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. Under normal circumstances, the indoor return air volume does not exceed 70% of the supply air volume, so Kmax takes a value of 0.7. At this time, the supply air parameters are adjusted by return air, the second air valve 82 and the fourth air valve 84 are opened, the first air valve 81 and the third air valve 83 are closed, and the outdoor fresh air enters the second surface cooler 42 upstream of the unit body 1 from the second air inlet 22, and the outdoor fresh air enters the second surface cooler 42 downstream of the unit body 1 from the return air port 9; the air volume of the second air valve 82 is adjusted to W1, the air volume of the fourth air valve 84 is adjusted to W2, and the second surface cooler 42 maintains the maximum hot water flow rate, so as to meet the supply air parameters and meet the requirements. When K2>0.7, the return air ratio is too large, and the supply air parameters are not adjusted by return air. At this time, the first air valve 81 is opened, and the second air valve 82, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the first surface cooler 41 in the unit body 1 through the first air inlet 21. Hot water is introduced into both the first surface cooler 41 and the second surface cooler 42. The second surface cooler 42 maintains the maximum hot water flow rate, and the supply air temperature Ts is controlled by adjusting the hot water flow rate of the first surface cooler 41.

[0090] If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler 42, the second air valve 82 is opened, the first air valve 81, the third air valve 83 and the fourth air valve 84 are closed, and the outdoor fresh air enters the upstream of the second surface cooler 42 in the unit body 1 through the second air inlet 22. Hot water is introduced into the second surface cooler 42, and the supply air temperature Ts is controlled by adjusting the hot water flow rate of the second surface cooler 42.

[0091] When the outdoor air temperature Tw is too high or the outdoor air humidity dw is too high (i.e., Tw > Tw2 or dw > dw2), the fresh air unit must operate in cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity. Then, based on the user-set fresh air volume Ws, it calculates the cooling capacity Qc required to cool the fresh air to the corresponding air enthalpy h2 at the cooling and dehumidification state point L1 (which can be 16°C, 90%, and 10.21g / kg). Qc = (hw - h2) * Ws.

[0092] If the required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler 42 (the rated cooling capacities of the first surface cooler 41 and the second surface cooler 42 are equal), the supply air parameters are first adjusted by return air to calculate how much outdoor fresh air the second surface cooler 42 can handle to the cooling and dehumidification state point L1 at the rated cooling capacity Ql. Assuming that the fresh air volume that can be handled is set to W3 and the indoor return air volume is set to W4,

[0093] W3=Q1 / (hw-h2),

[0094] W4=Ws-W3,

[0095] At this time, the ratio of fresh air volume to total air supply volume k3 is: k3=W3 / Ws,

[0096] The ratio of return air volume to total supply air volume K4 is: k4 = W4 / Ws.

[0097] Under normal circumstances, the indoor return air volume does not exceed 70% of the supply air volume. Therefore, when k4≤0.7, the supply air parameters are adjusted by return air, the second air valve 82 and the fourth air valve 84 are opened, the first air valve 81 and the third air valve 83 are closed, and the outdoor fresh air enters the second surface cooler 42 upstream of the unit body 1 from the second air inlet 22, and the outdoor fresh air enters the second surface cooler 42 downstream of the unit body 1 from the return air port 9; the air volume of the second air valve 82 is adjusted to W3, the air volume of the fourth air valve 84 is adjusted to W4, and the second surface cooler 42 maintains the maximum cold water flow rate, so as to meet the supply air parameters and meet the requirements. When K4>0.7, the return air ratio is too large, and the supply air parameters are not adjusted by return air. At this time, the first air valve 81 is opened, and the second air valve 82, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the first surface cooler 41 in the unit body 1 through the first air inlet 21. Cold water is passed through the first surface cooler 41 and the second surface cooler 42. The second surface cooler 42 maintains the maximum cold water flow. The supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler 41, and then the reheater 5 is judged whether to be turned on according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater 5 is kept closed; when Ts<Ts1, the reheater 5 is turned on.

[0098] If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler 42, the second air valve 82 is opened, and the first air valve 81, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the second surface cooler 42 in the unit body 1 through the second air inlet 22, and cold water is introduced into the second surface cooler 42. The supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler 42, and then the supply air temperature Ts is used to determine whether the reheater 5 is turned on: when Ts1≤Ts≤Ts2, keep the reheater 5 closed; when Ts<Ts1, turn on the reheater 5.

[0099] Example 3

[0100] The structure and principle of this embodiment are basically the same as those of the second embodiment, except that the position of the return air outlet 9 is different. Figure 4 As shown, in this embodiment, the return air inlet 9 is arranged between the downstream of the first surface cooler 41 and the upstream of the second surface cooler 42. For example, the return air inlet 9 is arranged close to the second air inlet 22. The air entering through the return air inlet 9 and the second air inlet 22 enters the unit body 1 after passing through the same filter 7.

[0101] The position of the return air outlet 9 of this embodiment is different from that of the second embodiment, and the operation control method of the fresh air unit is different from that of the second embodiment, as follows:

[0102] The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve 8, the surface cooler 4, and the reheater 5 according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows:

[0103] When the temperature Tw and humidity dw of the outdoor air meet the comfort requirements of indoor personnel, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler 41, the second surface cooler 42 and the reheater 5 are all closed, the first air valve 81, the second air valve 82 and the fourth air valve 84 are closed, and the third air valve 83 is opened. Outdoor fresh air enters through the third air inlet 23, and the fresh air unit operates in ventilation mode.

[0104] When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1,dw1≤dw≤dw2, the fresh air unit operates in heating mode. The controller first calculates the outdoor air enthalpy hw based on the outdoor temperature and humidity, and then calculates the heat Qh required to process the fresh air to the air state point corresponding to the enthalpy h1 at Tw1,dw based on the user-set fresh air volume Ws. Qh=(h1-hw)*Ws.

[0105] If the calculated required heat Qh is greater than the rated heat capacity Qr of the second surface cooler 42, the supply air parameters are first adjusted by return air. Assuming that the indoor return air temperature is Tb, the humidity is db, the corresponding air enthalpy value is hb, the indoor return air volume is W2, and the outdoor fresh air volume is W1, then when the rated heat capacity Qr and the set fresh air volume Ws are used, the second surface cooler 42 can process the mixed air with the maximum air enthalpy value hm at the state point after the fresh air and return air are mixed to the air state point Tw1,dm, where dm represents the mixed air humidity after the fresh air and return air are mixed.

[0106] dm=(dw*W1+db*W2) / (W1+W2),

[0107] hm=h1-(Qr / Ws),

[0108] W1=Ws*(hm-hb) / (hw-hb),

[0109] W2=Ws-W1,

[0110] At this time, the ratio of fresh air volume to total air volume k1 is: k1 = W1 / Ws,

[0111] The ratio of return air volume to total supply air volume k2 is: k2 = W2 / Ws;

[0112] When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. Under normal circumstances, the indoor return air volume does not exceed 70% of the supply air volume, so Kmax is set to 0.7. At this time, the supply air parameters are adjusted by return air, the second air valve 82 and the fourth air valve 84 are opened, the first air valve 81 and the third air valve 83 are closed, and the outdoor fresh air and return air enter the upstream of the second surface cooler 42 in the unit body 1 from the second air inlet 22 and the return air port 9 respectively; the air volume of the second air valve 82 is adjusted to W1, and the air volume of the fourth air valve 84 is adjusted to W2, and the second surface cooler 42 maintains the maximum hot water flow rate, so as to meet the supply air parameters and meet the requirements. When k2>0.7, the return air ratio is too large, and the supply air parameters are not adjusted by return air. At this time, the first air valve 81 is opened and the air volume is set to Ws. The second air valve 82, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the first surface cooler 41 in the unit body 1 through the first air inlet 21. Hot water is introduced into both the first surface cooler 41 and the second surface cooler 42. The second surface cooler 42 maintains the maximum hot water flow rate. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the first surface cooler 41.

[0113] If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler 42, the second air valve 82 is opened and the air volume is set to Ws. The first air valve 81, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the second surface cooler 42 in the unit body 1 through the second air inlet 22. Hot water is introduced into the second surface cooler 42. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the second surface cooler 42.

[0114] When the outdoor air temperature Tw or humidity dw is too high (i.e., Tw > Tw2 or dw > dw2), the fresh air unit operates in cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity. Then, based on the user-set fresh air volume Ws, it calculates the cooling capacity Qc required to process the fresh air to the cooling and dehumidification state point L2 (which can be 19°C, 90%, and 12.38g / kg) corresponding to the enthalpy h2. Qc = (hw - h2) * Ws. The air temperature and humidity corresponding to the cooling and dehumidification state point L2 are greater than those at the cooling and dehumidification state point L1.

[0115] If the calculated required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler 42 (the rated cooling capacities of the first and second surface coolers 41 and 42 are equal), the supply air parameters are first adjusted by return air. Assuming that the indoor return air temperature is Tb, the humidity is db, the corresponding air enthalpy is hb, the indoor return air volume is W4, and the outdoor fresh air volume is W3, then the single-stage surface cooler 4 can process the mixed air with the fresh air and return air at the state point where the air enthalpy value is the maximum hm to the cooling and dehumidification state point L2 at the rated cooling capacity Ql and the set fresh air volume Ws.

[0116] hm=h2+(Ql / Ws),

[0117] W3=Ws*(hm-hb) / (hw-hb),

[0118] W4=Ws-W3,

[0119] At this time, the ratio of fresh air volume to total air volume k3 is: k3 = W3 / Ws,

[0120] The ratio of return air volume to total supply air volume k4 is: k4 = W4 / Ws

[0121] Generally, the indoor return air volume does not exceed 70% of the supply air volume. Therefore, when k4≤0.7, the supply air parameters are adjusted by return air, the second air valve 82 and the fourth air valve 84 are opened, the first air valve 81 and the third air valve 83 are closed, and the outdoor fresh air and return air enter the upstream of the second surface cooler 42 in the unit body 1 from the second air inlet 22 and the return air port 9 respectively; the air volume of the second air valve 82 is adjusted to W3, and the air volume of the fourth air valve 84 is adjusted to W4, and the second surface cooler 42 maintains the maximum cold water flow rate, so as to meet the supply air parameters and meet the requirements. When k2>0.7, the return air accounts for too large a proportion, and the supply air parameters are not adjusted by return air. At this time, the first air valve 81 is opened and the air volume is set to Ws. The second air valve 82, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the first surface cooler 41 in the unit body 1 through the first air inlet 21. Cold water is introduced into the first surface cooler 41 and the second surface cooler 42. The second surface cooler 42 maintains the maximum cold water flow. The supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler 41, and then the reheater 5 is judged whether to open according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater 5 is kept closed; when Ts<Ts1, the reheater 5 is opened.

[0122] If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler 42, the supply air parameters are not adjusted by return air. The second air valve 82 is opened and the air volume is set to Ws. The first air valve 81, the third air valve 83 and the fourth air valve 84 are closed. The outdoor fresh air enters the upstream of the second surface cooler 42 in the unit body 1 through the second air inlet 22. Cold water is introduced into the second surface cooler 42. The supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler 42. Then, whether the reheater 5 is turned on is determined based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater 5 is kept closed; when Ts<Ts1, the reheater 5 is turned on.

[0123] Throughout this specification, reference to terms such as "preferred embodiment," "one embodiment," "some embodiments," "example," "specific example," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0124] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A vertical fresh air unit, characterized in that: The unit comprises a unit body having an air inlet and an air outlet, wherein a surface cooler and a fan are sequentially arranged inside the unit body along the height direction, wherein the surface cooler can heat or cool the air passing therethrough, and the fan is used to draw outdoor air into the unit body through the air inlet and discharge it from the air outlet; There are multiple air inlets, which are provided upstream and downstream of the surface cooler. Each air inlet is provided with a filter and an air valve for controlling the air flow at the air inlet.

2. A vertical fresh air unit according to claim 1, characterized in that: The plurality of air inlets are located on the same side of the outside of the unit body and are spaced apart along the height direction of the unit body; And / or the air outlet is located at the top of the unit body, and the surface cooler and the fan are arranged in sequence from bottom to top.

3. A vertical fresh air unit according to claim 1, characterized in that: There are two surface coolers, which are a first surface cooler and a second surface cooler spaced apart in the height direction. The air inlets are provided upstream of the first surface cooler, upstream of the second surface cooler, and downstream of the second surface cooler.

4. A vertical fresh air unit according to claim 1, characterized in that: The surface cooler is connected to a water circulation pipeline, and cold water is passed into the surface cooler through the water circulation pipeline to cool and dehumidify the air flowing through it. Hot water is passed into the surface cooler through the water circulation pipeline to heat and increase the temperature of the air flowing through it.

5. A vertical fresh air unit according to claim 6, characterized in that: A reheater is further provided in the unit body along the height direction between the second surface cooler and the fan, and the air inlet is also provided upstream of the reheater downstream of the second surface cooler; The air inlet arranged upstream of the first cooler is the first air inlet, and the air valve at the first air inlet is the first air valve. The air inlet arranged downstream of the first cooler and upstream of the second cooler is the second air inlet, and the air valve at the second air inlet is the second air valve. The air inlet arranged downstream of the second cooler is the third air inlet, and the air valve at the third air inlet is the third air valve.

6. A vertical fresh air unit according to claim 5, characterized in that: The reheater is connected to a water circulation pipeline, and hot water is introduced into the reheater through the water circulation pipeline to heat the air flowing through the reheater.

7. A vertical fresh air unit according to claim 5, characterized in that: It also includes an outdoor temperature and humidity sensor for measuring the outdoor air temperature and humidity, and a supply air temperature and humidity sensor for measuring the temperature and humidity of the air supplied to the room. The signal output ends of the outdoor temperature and humidity sensor and the supply air temperature and humidity sensor are connected to the input end of the controller, and the control output end of the controller is connected to the enable end of each air valve, surface cooler and reheater.

8. An operation control method of the vertical fresh air unit according to claim 7, characterized in that: The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows: When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first and second air valves are closed, and the third air valve is opened. Outdoor fresh air enters through the third air inlet, and the fresh air unit operates in ventilation mode; When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1, dw1≤dw≤dw2, the first and third air valves are closed, and the second air valve is opened. Outdoor fresh air enters through the second air inlet, and hot water is supplied to the second surface cooler. The fresh air unit operates in heating mode. The controller first adjusts the hot water flow of the second surface cooler according to the supply air temperature Ts: when the supply air temperature Ts1≤Ts≤Ts2, the hot water flow of the second surface cooler is kept unchanged; When Ts<Ts1, the hot water flow of the second cooler is increased; when Ts>Ts2, the hot water flow of the second cooler is reduced; when the second cooler reaches the maximum hot water flow, and Ts<Ts1 is still reached, the second air valve and the third air valve are closed, and the first air valve is opened. Outdoor fresh air enters through the first air inlet, and hot water is introduced into both the first and second coolers. The second cooler maintains the maximum hot water flow, and the controller adjusts the supply air temperature by adjusting the hot water flow of the first cooler. When the outdoor air temperature Tw is appropriate and the humidity dw is too high, that is, Tw1<Tw≤Tw2, dw>dw2, the first air valve and the third air valve are closed, and the second air valve is opened. Outdoor fresh air enters through the second air inlet, and cold water is passed into the second surface cooler. The fresh air unit operates in dehumidification mode, and the air entering the unit body is cooled and dehumidified by the second surface cooler before being sent into the room; When the supply air humidity ds1 < ds < ds2, the cold water flow of the second cooler is kept unchanged; when the supply air humidity ds < ds1, the cold water flow of the second cooler is reduced; when the supply air humidity ds > ds2, the cold water flow of the second cooler is increased; when the second cooler reaches the maximum cold water flow, and ds > ds2, the second air valve and the third air valve are closed, and the first air valve is opened. Outdoor fresh air enters through the first air inlet, and cold water is passed into the first and second coolers. The second cooler maintains the maximum cold water flow, and the controller adjusts the supply air humidity ds by adjusting the cold water flow of the first cooler; the controller then determines whether the reheater is turned on according to the supply air temperature Ts: when Ts1 ≤ Ts ≤ Ts2, the reheater is kept closed; when Ts < Ts1, the reheater is turned on and hot water is passed into it; When the outdoor air temperature Tw is too high and the humidity dw is too large, that is, Tw>Tw2, dw>dw2, close the first air valve and the third air valve, open the second air valve, and outdoor fresh air enters through the second air inlet. Cold water is introduced into the second surface cooler, and the fresh air unit operates in cooling mode; the controller adjusts the cold water flow of the second surface cooler according to the supply air temperature Ts and the supply air humidity ds: when the supply air temperature Ts1≤Ts≤Ts2 and the supply air humidity ds1<ds<ds2, keep the cold water flow of the second surface cooler unchanged; when Ts>Ts2 or ds>ds2, increase the cold water flow of the second surface cooler; when Ts<Ts1 and When ds<ds1, reduce the cold water flow of the second cooler; when the second cooler reaches the maximum cold water flow, Ts>Ts2 or ds>ds2, close the second air valve and the third air valve, open the first air valve, and allow outdoor fresh air to enter through the first air inlet. Cold water is passed into both the first cooler and the second cooler, and the second cooler maintains the maximum cold water flow. The controller adjusts the supply air humidity ds by adjusting the cold water flow of the first cooler, and then determines whether the reheater is turned on based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater and pass hot water into it.

9. An operation control method of the vertical fresh air unit according to claim 7, characterized in that: The unit body is further provided with a return air inlet located downstream of the second surface cooler, the return air inlet being used to introduce indoor air into the unit body, and a fourth air valve being provided at the return air inlet, wherein the first air valve, the second air valve, the third air valve and the fourth air valve are all variable air volume valves capable of adjusting the air volume; The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows: When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first air valve, the second air valve and the fourth air valve are closed, the third air valve is opened, and outdoor fresh air enters through the third air inlet. The fresh air unit operates in ventilation mode; When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1,dw1≤dw≤dw2, the fresh air unit operates in heating mode. The controller first calculates the current outdoor air enthalpy hw based on the outdoor temperature and humidity, and then calculates the heat Qh required for the fresh air to be processed to the air state point where Tw1,dw is located, corresponding to the enthalpy h1, based on the fresh air volume Ws set by the user. Qh=(h1-hw)*Ws, If the required heat Qh is greater than the rated heat Qr of the second surface cooler 42, the supply air parameters are first adjusted by return air. The amount of outdoor fresh air that the second surface cooler can handle to the air state point Tw1,dw at the rated heat Qr is calculated. Assuming that the amount of fresh air that can be handled is W1 and the amount of indoor return air is W2, W1=Qr / (h1-hw), W2=Ws-W1, At this time, the ratio of fresh air volume to total air supply volume k1 is: k1=W1 / Ws, The ratio of return air volume to total supply air volume k2 is: k2 = W2 / Ws; When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. The supply air parameters are adjusted by return air, the second air valve and the fourth air valve are opened, the first air valve and the third air valve are closed, the air volume of the second air valve is adjusted to W1, the air volume of the fourth air valve is adjusted to W2, and the second surface cooler maintains the maximum hot water flow, so as to meet the supply air parameter requirements; when k2>Kmax, the supply air parameters are not adjusted by return air, at this time the first air valve is opened, the second air valve, the third air valve and the fourth air valve are closed, hot water is passed into the first surface cooler and the second surface cooler, the second surface cooler maintains the maximum hot water flow, and the supply air temperature Ts is controlled by adjusting the hot water flow of the first surface cooler; If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler, the second air valve is opened, the first air valve, the third air valve and the fourth air valve are closed, hot water is introduced into the second surface cooler, and the supply air temperature Ts is controlled by adjusting the hot water flow of the second surface cooler; When the outdoor air temperature Tw is too high or the outdoor air humidity dw is too high, that is, Tw>Tw2 or dw>dw2, the fresh air unit operates in cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy value hw according to the outdoor temperature and humidity, and then calculates the cooling capacity Qc required for the fresh air to be processed to the cooling and dehumidification state point L1 corresponding to the enthalpy value h2 according to the user-set fresh air volume Ws. Qc=(hw-h2)*Ws, If the required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler, the supply air parameters are first adjusted by return air. The amount of outdoor fresh air that the second surface cooler can handle to the cooling and dehumidification state point L1 at the rated cooling capacity Ql is calculated. Assuming that the fresh air volume that can be handled is set to W3 and the indoor return air volume is set to W4, W3=Q1 / (hw-h2), W4=Ws-W3, At this time, the ratio of fresh air volume to total air supply volume k3 is: k3=W3 / Ws, The ratio of return air volume to total supply air volume k4 is: k4 = W4 / Ws; When k4≤Kmax, the supply air parameters are adjusted by returning air, the second air valve and the fourth air valve are opened, the first air valve and the third air valve are closed, the air volume of the second air valve is adjusted to W3, the air volume of the fourth air valve is adjusted to W4, and the second surface cooler maintains the maximum cold water flow, so as to meet the supply air parameter requirements; when k4>Kmax, the supply air parameters are not adjusted by returning air, at this time the first air valve is opened, the second air valve, the third air valve and the fourth air valve are closed, cold water is passed into the first surface cooler and the second surface cooler, the second surface cooler maintains the maximum cold water flow, and the supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler, and then the reheater is judged whether to open according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, the reheater is kept closed; when Ts<Ts1, the reheater is opened; If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler, the second air valve is opened, the first air valve, the third air valve and the fourth air valve are closed, cold water is introduced into the second surface cooler, and the supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler. Then, whether the reheater is turned on is determined based on the supply air temperature Ts: when TS1≤Ts≤TS2, the reheater is kept closed; when Ts<TS1, the reheater is turned on.

10. An operation control method of the vertical fresh air unit according to claim 7, characterized in that: The unit body is further provided with a return air inlet located between the downstream of the first surface cooler and the upstream of the second surface cooler, the return air inlet being used to introduce indoor air into the unit body, and a fourth air valve being provided at the return air inlet, the first air valve, the second air valve, the third air valve and the fourth air valve being variable air volume valves capable of adjusting the air volume; The outdoor temperature and humidity sensor detects the temperature and humidity of the outdoor air in real time and transmits them to the controller. The controller controls the opening and closing of each air valve, surface cooler, and reheater according to the temperature Tw and humidity dw of the outdoor air to make the supply air temperature Ts and supply air humidity ds detected by the supply air temperature and humidity sensor appropriate. The specific process is as follows: When the outdoor air temperature Tw and humidity dw both meet the indoor occupant comfort requirements, that is, Tw1<Tw≤Tw2, dw1≤dw≤dw2, the first surface cooler, the second surface cooler and the reheater are all closed, the first air valve, the second air valve and the fourth air valve are closed, the third air valve is opened, and outdoor fresh air enters through the third air inlet. The fresh air unit operates in ventilation mode; When the outdoor air temperature Tw is too low and the humidity dw is appropriate, that is, Tw≤Tw1,dw1≤dw≤dw2, the fresh air unit operates in heating mode. The controller first calculates the outdoor air enthalpy hw based on the outdoor temperature and humidity, and then calculates the heat Qh required for the fresh air to be processed to the air state point where Tw1,dw is located, corresponding to the air enthalpy h1, based on the fresh air volume Ws set by the user. Qh=(h1-hw)*Ws, If the calculated required heat Qh is greater than the rated heat capacity Qr of the second surface cooler, the supply air parameters are first adjusted by return air. Assuming that the indoor return air temperature is Tb, the humidity is db, the corresponding air enthalpy is hb, the indoor return air volume is W2, and the outdoor fresh air volume is W1, then when the second surface cooler has the rated heat capacity Qr and the set fresh air volume Ws, it can process the mixed air with the maximum air enthalpy value hm at the state point after the fresh air and return air are mixed to the air state point Tw1,dm, where dm represents the mixed air humidity after the fresh air and return air are mixed. dm=(dw*W1+db*W2) / (W1+W2), hm=h1-(Qr / Ws), W1=Ws*((hm-hb) / (hw-hb)), W2=Ws-W1, At this time, the ratio of fresh air volume to total air volume k1 is: k1 = W1 / Ws, The ratio of return air volume to total supply air volume k2 is: k2 = W2 / Ws; When k2≤Kmax, Kmax is a constant, which is the maximum value of the ratio of return air to total supply air volume. The second and fourth air valves are opened, and the first and third air valves are closed. The air volume of the second air valve is adjusted to W1, and the air volume of the fourth air valve is adjusted to W2. The second surface cooler maintains the maximum hot water flow rate to meet the supply air parameter requirements. When k2>Kmax, the supply air parameters are not adjusted by return air. At this time, the first air valve is opened and the air volume is set to Ws. The second, third and fourth air valves are closed. Hot water is introduced into the first and second surface coolers. The second surface cooler maintains the maximum hot water flow rate. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the first surface cooler. If the calculated required heat Qh is less than the rated heat Qr of the second surface cooler, then open the second air valve and set the air volume to Ws. The first, third, and fourth air valves are closed, and hot water is supplied to the second surface cooler. The supply air temperature Ts is controlled by adjusting the hot water flow rate of the second surface cooler. When the outdoor air temperature Tw is too high or the humidity dw is too high, that is, Tw>Tw2 or dw>dw2, the fresh air unit operates in cooling and dehumidification mode. The controller first calculates the current outdoor air enthalpy value hw according to the outdoor temperature and humidity, and then calculates the cooling capacity Qc required for the fresh air to be processed to the cooling and dehumidification state point L2 corresponding to the air enthalpy value h2 according to the user-set fresh air volume Ws. Qc=(hw-h2)*Ws, If the calculated required cooling capacity Qc is greater than the rated cooling capacity Ql of the second surface cooler, the supply air parameters are first adjusted by return air. Assuming that the indoor return air temperature is Tb, the humidity is db, the corresponding air enthalpy is hb, the indoor return air volume is W4, and the outdoor fresh air volume is W3, then the single-stage surface cooler can process the mixed air with the maximum air enthalpy value hm after the fresh air and return air are mixed to the cooling and dehumidification state point L2 when the rated cooling capacity Ql and the set fresh air volume Ws are hm=h2+(Ql / Ws), W3=Ws*((hm-hb) / (hw-hb)), W4=Ws-W3, At this time, the ratio of fresh air volume to total air volume k3 is: k3 = W3 / Ws, The ratio of return air volume to total supply air volume k4 is: k4 = W4 / Ws When k4≤Kmax, open the second air valve and the fourth air valve, close the first air valve and the third air valve, adjust the air volume of the second air valve to W3, and the air volume of the fourth air valve to W4, and maintain the maximum cold water flow of the second surface cooler to meet the requirements of the air supply parameters; when k2>Kmax, the air supply parameters are not adjusted by returning the air. At this time, open the first air valve and set the air volume to Ws, and close the second air valve, the third air valve and the fourth air valve. Cold water is passed through the first and second surface coolers, and the second surface cooler maintains the maximum cold water flow. The supply air humidity ds is controlled by adjusting the cold water flow of the first surface cooler, and then judge whether the reheater is turned on according to the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater; If the calculated required cooling capacity Qc is less than the rated cooling capacity Ql of the second surface cooler, open the second air valve and set the air volume to Ws. The first air valve, the third air valve and the fourth air valve are closed. Cold water is introduced into the second surface cooler. The supply air humidity ds is controlled by adjusting the cold water flow of the second surface cooler. Then, whether the reheater is turned on is determined based on the supply air temperature Ts: when Ts1≤Ts≤Ts2, keep the reheater closed; when Ts<Ts1, turn on the reheater.

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