阅读说明：本技术 风量测量装置、地铁空调系统和控制方法 (Air quantity measuring device, subway air conditioning system and control method ) 是由 李晓锋 王斌 李亮 王岩 钱振宇 李严 王春旺 于 2021-07-13 设计创作，主要内容包括：本发明实施例提供了一种风量测量装置、地铁空调系统和控制方法,其中,风量测量装置包括：静压室,设置有第一开口、第二开口和第三开口,静压室用于通过第一开口与地铁空调系统的回风室连接,且通过第二开口与地铁空调系统的排风道连接；稳压管,包括相连接的第一管段和第二管段,第一管段和第二管段的管径相同,静压箱通过第三开口与第一管段连接,第二管段用于与排风道连接；孔板压差流量计,设置于第一管段与第二管段之间,其中,在地铁空调系统的小新风模式开启时,第一开口和第三开口开启,第二开口关闭,孔板压差流量计用于测量压差,以用于测量排风道的排风量。本发明实施例能够实现对新风量较为精确的测量。(The embodiment of the invention provides an air volume measuring device, a subway air conditioning system and a control method, wherein the air volume measuring device comprises: the static pressure chamber is provided with a first opening, a second opening and a third opening, and is used for being connected with an air return chamber of the subway air conditioning system through the first opening and being connected with an air exhaust duct of the subway air conditioning system through the second opening; the pressure stabilizing pipe comprises a first pipe section and a second pipe section which are connected, the pipe diameters of the first pipe section and the second pipe section are the same, the static pressure box is connected with the first pipe section through a third opening, and the second pipe section is used for being connected with an exhaust duct; and the orifice plate differential pressure flowmeter is arranged between the first pipe section and the second pipe section, wherein when the small fresh air mode of the subway air conditioning system is started, the first opening and the third opening are opened, the second opening is closed, and the orifice plate differential pressure flowmeter is used for measuring differential pressure so as to be used for measuring the air exhaust volume of the air exhaust duct. The embodiment of the invention can realize more accurate measurement of the fresh air volume.)

1. The utility model provides an amount of wind measuring device for subway air conditioning system, its characterized in that, amount of wind measuring device includes:

the static pressure chamber is provided with a first opening, a second opening and a third opening, and is used for being connected with an air return chamber of the subway air conditioning system through the first opening and being connected with an exhaust duct of the subway air conditioning system through the second opening;

the pressure stabilizing pipe comprises a first pipe section and a second pipe section which are connected, the pipe diameters of the first pipe section and the second pipe section are the same, the static pressure box is connected with the first pipe section through the third opening, and the second pipe section is used for being connected with the exhaust duct; and

an orifice plate differential pressure flow meter disposed between the first pipe segment and the second pipe segment,

when the subway air conditioning system is started in a small fresh air mode, the first opening and the third opening are opened, the second opening is closed, part of return air in the air return chamber sequentially flows into the exhaust duct through the static pressure chamber and the pressure stabilizing pipe, and the orifice plate differential pressure flowmeter is used for measuring differential pressure and measuring the exhaust volume of the exhaust duct.

2. The air volume measuring device according to claim 1, wherein a central axis of the first duct section coincides with a central axis of the second duct section.

3. The air volume measuring device according to claim 1, wherein the length of the first duct section is greater than the length of the second duct section.

4. The air volume measuring device according to claim 1, wherein an aperture of the differential orifice plate pressure flowmeter near the static pressure chamber is smaller than an aperture of the differential orifice plate pressure flowmeter far from the static pressure chamber.

5. The air volume measuring device according to claim 1, wherein the first tube section and the second tube section are integrally formed to form the pressure stabilizing tube, and the orifice plate differential pressure flow meter is arranged in a tube of the pressure stabilizing tube.

6. The air volume measuring device according to claim 1, wherein the first opening, the second opening, and the third opening are respectively provided on different sides of the static pressure chamber.

7. A subway air conditioning system, comprising:

the air return chamber is provided with an air return inlet, a first air outlet and a second air outlet;

the air mixing chamber is provided with a brand new air inlet, a first air inlet and an air supply outlet, and the first air inlet is connected with the first air outlet;

an exhaust duct;

the fresh air duct is connected with the fresh air port;

the air volume measuring device is the air volume measuring device according to any one of claims 1 to 6, a static pressure chamber of the air volume measuring device is connected with the second air outlet through a first opening, the static pressure chamber is connected with the exhaust duct through a second opening, and a second pipe section of a pressure stabilizing pipe of the air volume measuring device is connected with the exhaust duct.

8. A subway air conditioning system as claimed in claim 7, wherein said air exhaust duct of said subway air conditioning system is provided with an air exhaust interlayer, and said air quantity measuring device is arranged in the space formed by said air exhaust interlayer.

9. A control method of a subway air-conditioning system for controlling the subway air-conditioning system as claimed in claim 7 or 8, said method comprising:

when the opening of a small fresh air mode of the subway air conditioning system is detected, controlling a first opening and a third opening of a static pressure chamber of an air volume measuring device to be opened, and controlling a second opening of the static pressure chamber to be closed;

acquiring the differential pressure measured by a pore plate differential pressure flowmeter of the air volume measuring device;

calculating the air exhaust volume of the subway air conditioning system according to the differential pressure, the aperture of the orifice plate differential pressure flowmeter and the pipe diameter of a voltage stabilizing pipe of the air volume measuring device;

and obtaining the fresh air volume of the subway air conditioning system according to the air exhaust volume.

Technical Field

The invention belongs to the technical field of subway air conditioners, and particularly relates to an air quantity measuring device, a subway air conditioner system and a control method.

Background

The subway station is generally provided with an air conditioning system, and when the air conditioning system works in a small fresh air mode, fresh air can be introduced into the subway station. Because the passenger flow of the subway station is generally large, the fresh air intake determines the air condition in the subway station, and therefore, the fresh air intake (which can be called as "fresh air volume" for short) of the subway station becomes a key parameter required to be considered for the operation of the subway air conditioning system. However, the size of a fresh air valve of the existing subway air conditioning system is generally large, a large gap exists, and the problem of fresh air leakage exists even under the condition of small pressure difference, so that the fresh air volume is difficult to measure, and the operation effect of the subway air conditioning system is poor.

Disclosure of Invention

The embodiment of the invention provides an air volume measuring device, a subway air conditioning system and a control method, which can realize more accurate measurement of fresh air volume.

In a first aspect, an embodiment of the present invention provides an air volume measuring device, which is used for a subway air conditioning system, and includes:

the static pressure chamber is provided with a first opening, a second opening and a third opening, and is used for being connected with an air return chamber of the subway air conditioning system through the first opening and being connected with an exhaust duct of the subway air conditioning system through the second opening;

the pressure stabilizing pipe comprises a first pipe section and a second pipe section which are connected, the pipe diameters of the first pipe section and the second pipe section are the same, the static pressure box is connected with the first pipe section through the third opening, and the second pipe section is used for being connected with the exhaust duct; and

an orifice plate differential pressure flow meter disposed between the first pipe segment and the second pipe segment,

when the subway air conditioning system is started in a small fresh air mode, the first opening and the third opening are opened, the second opening is closed, part of return air in the air return chamber sequentially flows into the exhaust duct through the static pressure chamber and the pressure stabilizing pipe, and the orifice plate differential pressure flowmeter is used for measuring differential pressure and measuring the exhaust volume of the exhaust duct.

In a second aspect, an embodiment of the present invention provides a subway air conditioning system, including:

the air return chamber is provided with an air return inlet, a first air outlet and a second air outlet;

the air mixing chamber is provided with a brand new air inlet, a first air inlet and an air supply outlet, and the first air inlet is connected with the first air outlet;

an exhaust duct;

the fresh air duct is connected with the fresh air port;

the air quantity measuring device is the air quantity measuring device of the first aspect, a static pressure chamber of the air quantity measuring device is connected with the second air outlet through a first opening, the static pressure chamber is connected with the exhaust duct through a second opening, and a second pipe section of a voltage stabilizing pipe of the air quantity measuring device is connected with the exhaust duct.

In a third aspect, an embodiment of the present invention provides a method for controlling a subway air conditioning system, for controlling the subway air conditioning system described in the second aspect, where the method includes:

when the opening of a small fresh air mode of the subway air conditioning system is detected, controlling a first opening and a third opening of a static pressure chamber of an air volume measuring device to be opened, and controlling a second opening of the static pressure chamber to be closed;

acquiring the differential pressure measured by a pore plate differential pressure flowmeter of the air volume measuring device;

calculating the air exhaust volume of the subway air conditioning system according to the differential pressure, the aperture of the orifice plate differential pressure flowmeter and the pipe diameter of a voltage stabilizing pipe of the air volume measuring device;

and obtaining the fresh air volume of the subway air conditioning system according to the air exhaust volume.

In the embodiment of the invention, the air volume measuring device is arranged between the air return chamber and the exhaust duct of the subway air-conditioning system, and when the small fresh air mode of the subway air-conditioning system is started, the exhaust air is firstly discharged through the pressure stabilizing pipe and then discharged through the exhaust duct, so that the exhaust air volume can be calculated according to the differential pressure measured by the orifice plate differential pressure flowmeter. Because the air exhaust volume is basically equal to the fresh air volume, the fresh air volume can be obtained from the air exhaust volume, and the fresh air volume can be accurately measured.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a subway air conditioning system in the prior art;

fig. 2 is a schematic structural diagram of a subway air conditioning system provided with a wind volume measuring device according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an orifice plate differential pressure flow meter provided with a pressure-stabilizing tube according to an embodiment of the invention;

FIG. 4 is a side and front view of an annular orifice plate provided by an embodiment of the present invention;

fig. 5 is a flowchart illustrating a control method of a subway air conditioning system according to an embodiment of the present invention;

fig. 6 is a schematic view of an air return and exhaust control flow of the subway air conditioning system provided by the embodiment of the invention.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Fig. 1 shows a schematic structural diagram of a subway air conditioning system in the prior art.

As shown in fig. 1, a subway air conditioning system generally includes main components such as an air return chamber 11, an air mixing chamber 12, an exhaust duct 13, a fresh air duct 16, a small fresh air blower 17, and an air supply blower 14, wherein the air return chamber 11 is connected with the air mixing chamber 12 and the exhaust duct 13, and a part of return air in the air return chamber 11 enters the air mixing chamber 12, and the other part of return air enters the exhaust duct 13. The fresh air duct 16 is connected to the air mixing chamber 12, and when the small fresh air blower 17 is turned on, fresh air enters the air mixing chamber 12. The air mixing chamber 12 is also connected with a blast fan 14 for supplying the introduced fresh air and part of the return air to the subway station.

At present, the fresh air volume is mainly controlled through the fresh air valve 18, and as the size of the fresh air valve is large, a large gap exists, and the problem of fresh air leakage exists even under the condition of small pressure difference, the fresh air volume is difficult to measure, so that the operation effect of the subway air conditioning system is poor.

In view of this, the embodiment of the invention provides an air volume measuring device, a subway air conditioning system and a control method, which can realize accurate measurement of fresh air volume.

Fig. 2 shows a schematic structural diagram of a subway air conditioning system provided with a wind volume measuring device according to an embodiment of the present invention.

As shown in fig. 2, the air volume measuring device 20, which is used for a subway air conditioning system, may include:

the static pressure chamber 21, the static pressure chamber 21 is provided with a first opening 211, a second opening 212 and a third opening 213, the static pressure chamber 21 is used for being connected with the air return chamber 11 of the subway air conditioning system through the first opening 211, and is connected with the exhaust duct 13 of the subway air conditioning system through the second opening 212;

the pressure stabilizing pipe 22 comprises a first pipe section 221 and a second pipe section 222 which are connected, the pipe diameters of the first pipe section 221 and the second pipe section 222 are the same, the static pressure box is connected with the first pipe section 221 through a third opening 213, and the second pipe section 222 is used for being connected with the exhaust duct 13; and

an orifice differential pressure flow meter 23, disposed between the first pipe section 221 and the second pipe section 222,

when the small fresh air mode of the subway air conditioning system is started, the first opening 211 and the third opening 213 are opened, the second opening 212 is closed, part of return air in the air return chamber 11 sequentially flows into the exhaust duct 13 through the static pressure chamber 21 and the pressure stabilizing pipe 22, and the orifice plate differential pressure flow meter 23 is used for measuring differential pressure and measuring the exhaust volume of the exhaust duct 13.

Since the static pressure chamber 21 is provided between the air return chamber 11 and the exhaust duct 13, part of the return air (which can be understood as to be exhausted) from the air return chamber 11 must pass through the static pressure chamber 21 to enter the exhaust duct 13, and the accommodation space of the static pressure chamber 21 is generally large, so that the pressure of the return air entering the static pressure chamber 21 can be primarily stabilized in the static pressure chamber 21. The purpose of the second opening 212 and the third opening 213 of the static pressure chamber 21 is to enable the air to be exhausted to enter the exhaust duct 13 through two paths, wherein one path directly enters the exhaust duct 13 from the second opening 212 of the static pressure chamber 21 and can correspond to a single-row ventilation mode, and the other path enters the pressure stabilizing tube 22 from the third opening 213 of the static pressure chamber 21 and enters the exhaust duct 13 through the pressure stabilizing tube 22 and can correspond to a small fresh air mode.

The shape of the static pressure chamber 21 may not be limited, and as an example, the static pressure chamber 21 may be a static pressure box, i.e., box-shaped. The first opening 211, the second opening 212 and the third opening 213 of the static pressure chamber 21 can each be switched between an open state and a closed state.

The tube diameters (inner diameters) of the pressure stabilizing tubes 22 at different positions are the same, the length of the pressure stabilizing tube 22 can be longer, and the pressure stabilizing tube 22 with longer length can better stabilize the flow pattern, so that the pressure in each position in the pressure stabilizing tube 22 is more uniform.

As shown in fig. 3 to 4, the orifice differential pressure flowmeter 23 may include an annular orifice plate 231, a measuring instrument (not shown), and the like, wherein the annular orifice plate 231 has a certain orifice plate thickness E (also, an orifice thickness), a hole is formed in the center of the annular orifice plate 231, the hole has an aperture D smaller than the pipe diameter D of the stabilivolt 22, a chamfer F is provided on one side of the hole, and the orifice has a thickness E. The annular orifice plate 231 can function as a throttling member, and therefore, the annular orifice plate 231 may also be referred to as a throttling member. The two sides of the annular orifice plate 231 may be respectively provided with a measuring instrument to measure the pressure difference passing through the annular orifice plate 231, the measuring instrument may be, for example, a differential pressure transducer, the pressure may be obtained by a flange, and the pressure measuring hole may be provided in the flange.

Since the chamfer F is provided on one side of the orifice, the aperture of the differential orifice pressure flowmeter 23 near the static pressure chamber 21 is not equal to the aperture of the differential orifice pressure flowmeter 23 far from the static pressure chamber 21, which causes the airflow to pass through the differential orifice pressure flowmeter 23 to generate a differential pressure. Therefore, the exhaust air volume can be calculated according to the measured differential pressure, and parameters such as the pipe diameter D of the pressure stabilizing pipe 22, the aperture D of the aperture plate differential pressure flowmeter 23, the aperture plate thickness E, the chamfer F, the orifice thickness E and the like.

When the subway air conditioning system is started in a small fresh air mode, the air volume of the subway air conditioning system relates to fresh air volume, exhaust air volume, return air volume and air volume, and the relationship among the air volumes is as follows: the exhaust air quantity is the fresh air quantity, the return air quantity is the air supply quantity. Therefore, if the air discharge quantity can be measured more accurately, the more accurate fresh air quantity can be obtained.

Therefore, when the small fresh air mode is started, the air exhaust amount can be calculated according to the pressure difference by closing the second opening 212, opening the first opening 211 and the third opening 213, enabling air to be exhausted to enter the pressure stabilizing tube 22 through the static pressure chamber 21, and measuring the pressure difference through the orifice plate pressure difference flowmeter 23 arranged at the pressure stabilizing tube 22. According to the air volume balance, the air volume is equal to the fresh air volume, so the fresh air volume is obtained simultaneously by calculating the air volume.

It should be noted that, for the subway air conditioning system provided with the air volume measuring device 20, an exhaust valve may not be provided, and the static pressure chamber 21 of the air volume measuring device 20 may function as a valve instead of the exhaust valve. Of course, an exhaust valve may be disposed between the air volume measuring device 20 and the exhaust duct 13, which is not limited in the embodiment of the present invention.

In the embodiment of the invention, the air volume measuring device 20 is arranged between the air return chamber 11 and the exhaust duct 13 of the subway air-conditioning system, when the small fresh air mode of the subway air-conditioning system is started, the exhaust air is firstly discharged through the pressure stabilizing tube 22 and then through the exhaust duct 13, and thus, the exhaust air volume can be calculated according to the differential pressure measured by the orifice plate differential pressure flowmeter 23. Because the air exhaust volume is basically equal to the fresh air volume, the fresh air volume can be obtained from the air exhaust volume, and the fresh air volume can be accurately measured.

In some embodiments, the central axis of the first tube segment 221 coincides with the central axis of the second tube segment 222.

That is to say, the stabilivolt 22 is a straight tube, and the stabilivolt 22 is longer in length, therefore, the stabilivolt 22 is a long straight tube, so that the stabilivolt effect of the stabilivolt 22 can be improved to a greater extent, and the calculation accuracy of the air exhaust amount can be further improved.

In some embodiments, the length of the first tube segment 221 is greater than the length of the second tube segment 222.

As shown in FIG. 3, the first tube segment 221 has a length L1, the second tube segment 222 has a length L2, and L1 is greater than L2.

In this embodiment, the first pipe section 221 is set to be longer, so that the distance between the static pressure chamber 21 and the orifice plate differential pressure flowmeter 23 is longer, and thus, the air to be exhausted in the static pressure chamber 21 can pass through the longer pipe section to achieve a better pressure stabilizing effect, and the differential pressure measurement result of the orifice plate differential pressure flowmeter 23 is more accurate, so that the calculation accuracy of the air exhaust amount can be further improved.

In some embodiments, the aperture of the differential orifice plate pressure flow meter 23 proximate to the static pressure chamber 21 is smaller than the aperture of the differential orifice plate pressure flow meter 23 distal from the static pressure chamber 21.

Thus, when the exhaust air flows into the exhaust duct 13 from the static pressure chamber 21 through the pressure stabilizing pipe 22, a pressure drop exists on two sides of the orifice plate differential pressure flowmeter 23, and the measured pressure difference value is a negative value.

In some embodiments, the first 221 and second 222 segments are integrally formed to form the plenum 22, and the orifice plate differential pressure flow meter 23 is disposed within the tubing of the plenum 22.

In this embodiment, the first pipe section 221 and the second pipe section 222 are integrally formed, so that the mechanical parameters of each part of the pressure stabilizing pipe 22 are uniform, the pressure stabilizing effect of the pressure stabilizing pipe 22 can be improved to a greater extent, and the calculation accuracy of the air discharge amount can be further improved.

In some embodiments, the first opening 211, the second opening 212, and the third opening 213 are each disposed on different sides of the static pressure chamber 21. For example, the first opening 211 and the third opening 213 may be disposed on two opposite sides of the static pressure chamber 21, respectively, the second opening 212 and the third opening 213 may be disposed on two adjacent sides of the static pressure chamber 21, respectively, and so on.

The embodiment of the invention also provides a subway air conditioning system.

As shown in fig. 2, the subway air conditioning system includes:

the air return chamber 11, the air return chamber 11 has air return port 111, first air outlet 112 and second air outlet 113;

the air mixing chamber 12 is provided with a fresh air port 123, a first air inlet 121 and an air supply port 122, and the first air inlet 121 is connected with the first air outlet 112;

an exhaust duct 13;

the fresh air duct 16, the fresh air duct 16 is connected with the fresh air port 123;

the static pressure chamber 21 of the air volume measuring device 20 is connected with the second air outlet 113 through the first opening 211, the static pressure chamber 21 is connected with the exhaust duct 13 through the second opening 212, and the second pipe section 222 of the pressure stabilizing pipe 22 of the air volume measuring device 20 is connected with the exhaust duct 13.

Specifically, the fresh air duct 16 may be connected to the fresh air port 123 through the fresh air valve 19.

The subway air conditioning system of the embodiment of the invention can cancel a small fresh air fan, fresh air can be directly introduced into the subway station 30 through the entrance and exit of the subway station 30, and the fresh air can also be introduced into the air mixing chamber 12 through the fresh air duct 16 and the fresh air opening 123. In the embodiment of the present invention, the fresh air amount is the return air amount, and the air supply amount is the exhaust air amount, and since the air amount measurement and control device 20 is disposed in the exhaust duct 13, the exhaust air amount can be measured by the air amount measurement and control device 20.

The air volume measuring device according to the embodiment of the present invention is any one of the air volume measuring devices provided in the above embodiments, and can achieve the same technical effect, and for avoiding repetition, the details are not described here.

In some embodiments, the air exhaust duct 13 of the subway air conditioning system is provided with an air exhaust interlayer, and the air quantity measuring device is arranged in a space formed by the air exhaust interlayer.

Therefore, on one hand, the air volume measuring device can not occupy redundant space, and on the other hand, the air exhaust interlayer can also protect the air volume measuring device to a certain extent.

In the embodiment of the invention, the air volume measuring device 20 is arranged between the air return chamber 11 and the exhaust duct 13 of the subway air-conditioning system, when the small fresh air mode of the subway air-conditioning system is started, the exhaust air is firstly discharged through the pressure stabilizing tube 22 and then through the exhaust duct 13, and thus, the exhaust air volume can be calculated according to the differential pressure measured by the orifice plate differential pressure flowmeter 23. Because the air exhaust volume is basically equal to the fresh air volume, the fresh air volume can be obtained from the air exhaust volume, and the fresh air volume can be accurately measured.

Other configurations and operations of the air conditioning system for the subway according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail herein.

Fig. 5 is a flowchart illustrating a method for controlling a subway air conditioning system according to an embodiment of the present invention.

The control method of the subway air conditioning system is used for controlling the subway air conditioning system shown in fig. 2, and as shown in fig. 5, the control method of the subway air conditioning system comprises the following steps:

step 301: when the opening of a small fresh air mode of the subway air conditioning system is detected, controlling a first opening and a third opening of a static pressure chamber of an air quantity measuring device to be opened, and controlling a second opening of the static pressure chamber to be closed;

step 302: acquiring the differential pressure measured by a pore plate differential pressure flowmeter of the air quantity measuring device;

step 303: calculating the air exhaust volume of the subway air conditioning system according to the pressure difference, the parameters of the orifice plate pressure difference flow meter and the parameters of a pressure stabilizing tube of the air measuring device;

step 304: and obtaining the fresh air volume of the subway air conditioning system according to the air exhaust volume.

In step 303, the parameters of the orifice plate differential pressure flowmeter may include parameters such as an aperture, an orifice plate thickness, a chamfer, and an orifice thickness, and the parameters of the stabilivolt may include parameters such as a tube diameter and a tube length.

Therefore, through the process, the fresh air volume can be accurately measured.

In the embodiment of the invention, after the accurate measurement of the fresh air volume is realized, the return air volume (namely the return air volume and the exhaust air volume) can be controlled, and the control logic is as follows:

as shown in fig. 6, the carbon dioxide concentration of the return air is monitored, and if the carbon dioxide concentration exceeds a limit value, such as 1500PPM, it indicates that the fresh air is insufficient at this time, the fresh air needs to be supplemented and introduced, and the return air exhaust amount needs to be increased, such as increasing the frequency of the return air exhaust fan by 1 Hz. If the pressure difference between the two ends of the air volume measuring device is positive (namely dP is more than or equal to 0), the air exhaust duct exhausts air outwards, and fresh air can be introduced from the inlet and the outlet to reduce the concentration of carbon dioxide in the subway station. When the concentration of carbon dioxide is lower than the limit value, the system is required to ensure a zero mechanical fresh air state, if the pressure difference between two ends of the air volume measuring device is positive (namely dP is larger than 0), the exhaust duct exhausts air outwards, the frequency of the exhaust fan (namely the air return fan and the exhaust fan) can be reduced, for example, the frequency of the exhaust fan is reduced by 1Hz, and the positive pressure of the air return chamber is reduced until the zero pressure state (namely dP is 0) in which air is not exhausted outwards; if the pressure difference between the two ends of the air volume measuring device is negative, the air volume measuring device indicates that the air in the air return chamber is negative pressure (namely dP is less than 0), the air in the exhaust duct is sucked inwards, and the running frequency of the air return fan can be increased at the moment, so that the full pressure of the air return chamber is increased until the air is not discharged outwards or sucked inwards, and the zero mechanical fresh air running is achieved at the moment.

In the embodiment, the fresh air volume can be adjusted by controlling the operating frequency of the return exhaust fan, so that the fresh air volume meets the operating requirement of the subway air conditioning system, and the operating effect of the subway air conditioning system can be improved.

It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.