Air volume measurement and control integrated variable air volume air supply valve and control method

Abstract

The invention discloses an air volume measurement and control integrated variable air volume air supply valve and a control method. The air supply valve comprises a torque valve, and a torque sensor and an angle sensor are installed on a valve shaft of the torque valve; an electric actuator is installed on a valve body of the torque valve, the execution output end of the electric actuator is connected with a valve shaft of the torque valve, the signal output end of the torque sensor and the signal output end of the angle sensor are connected with the signal input end of the controller, and the signal output end of the controller is connected with the signal input end of the electric actuator. The air volume measuring technology is integrated into the valve body, an additional air volume sensor does not need to be installed in the air supply pipeline, the system complexity is reduced, and equipment energy consumption is reduced; and the measurement precision can be within 4%.

Description

TECHNICAL FIELD

[0001] The present application relates to a building ventilation system debugging device, in particular to a wind volume measurement and control integrated variable air volume supply valve and a control method. BACKGROUND

[0002] Variable air volume (VAV) air conditioning system is the main means to realize the time and zone adjustment of building ventilation. Among them, VAV BOX is an important component, which usually adjusts the air supply volume according to the changes of indoor temperature and humidity. Although this method can meet the basic air conditioning demand, in practical application, the changes of temperature and humidity cannot fully reflect the changes of indoor air quality, especially the changes of particulate matter concentration related to human activities. Therefore, the traditional air supply volume adjustment method has certain limitations in effectively improving indoor air quality and ensuring a healthy and comfortable environment, and cannot fully meet the demand of modern buildings for air quality control.

[0003] The existing VAV BOX is generally composed of a box body, a wind volume flow meter, a wind volume regulating valve and an actuator. However, the traditional wind volume flow meter has some inherent limitations in application. For example, the space in the building is limited, and it is usually difficult to meet the length requirement of the straight pipe section before and after installation, which affects the wind volume measurement accuracy; the wind volume flow meter has a small range ratio, which leads to an increase in measurement error at low flow rate. In addition, the additional installation of the wind volume flow meter not only increases the system complexity, but also causes a permanent pressure loss that cannot be ignored. Therefore, the wind volume measurement and control integrated technology emerges as the times require, among which the valve "virtual flow meter" has the most potential and is widely concerned. It indirectly measures the wind volume by using the working characteristics of the valve, such as the pressure difference before and after the valve. However, the pressure difference type valve flow meter can only measure the single-point pressure in the pipeline, and cannot fully reflect the overall pressure distribution in the pipeline. Therefore, the problem of flow measurement accuracy under non-ideal installation conditions has not been effectively solved. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a wind volume measurement and control integrated variable air volume supply valve and a control method, which have simple structure, low energy consumption and high accuracy.

[0005] The technical scheme of the present application is as follows:

[0006] The present application provides a wind volume measurement and control integrated variable air volume supply valve, which comprises a torque valve, a torque sensor and an angle sensor are respectively installed on the valve shaft of the torque valve; an electric actuator is installed on the valve body of the torque valve, the execution output end of the electric actuator is connected with the valve shaft of the torque valve, the signal output end of the torque sensor and the angle sensor is connected with the signal input end of the controller, and the signal output end of the controller is connected with the signal input end of the electric actuator.

[0007] The application discloses a control method of a wind volume measurement and control integrated variable air volume air supply valve.

[0008] Step one, taking a valve opening angle value theta as the horizontal coordinate and taking a valve torque flow coefficient K(theta) as the vertical coordinate, a corresponding relation curve between the torque flow coefficient K(theta) of the torque valve and the opening angle value theta is established and is stored in the controller, and the K(theta) calculation formula is as follows;

[0009]

[0010] Wherein, K(theta) is the valve torque flow coefficient; theta is the valve opening angle value; Q s is the current air supply flow, m 3 / h; alpha is the area ratio of the valve plate projection in the vertical air flow direction to the pipeline area when the torque valve is closed; rho is the air density, kg / m 3 ; beta is the air flow flow-through area ratio of the torque valve to the pipeline area; A1 is the cross-sectional area of the pipeline where the torque valve is installed, m 2 ; N is the valve torque value of the torque valve, Nm;

[0011] Step two, the torque valve valve torque and valve opening degree are measured to measure the air volume, and the specific process is as follows: the controller reads the valve torque value N output by the torque sensor and the opening angle value theta of the torque valve output by the angle sensor, and then the current air supply flow in the room is calculated through the following formula:

[0012]

[0013] Step three, the controller receives the indoor particulate matter concentration value output by the particulate matter concentration sensor arranged in the room, and the required air supply flow Q n in the room is calculated through a mass balance equation, wherein it is assumed that the particulate matter is uniformly mixed in the room.

[0014] The mass balance equation formula is as follows:

[0015] VdC i = Q n C0·(1-e)dt+GVdt-Q e C i dt

[0016] Wherein, V is the room volume, m 3 ; C i is the indoor particulate matter concentration value, p / m 3 ; C0 is the particulate matter concentration value in the air supply, p / m 3 ; Q n is the required air supply flow, m 3 / h; Q e is the exhaust flow, m3 h; e is filter efficiency in air handling unit; dC i is dC i ifferential; dt is differential with respect to t; G is average particle generation rate in room, p / (m 3 .h);

[0017]

[0018] wherein q refers to dust emission rate of decorative material, p / (min.m 2 ); H is room height, m; q' is particle generation rate of one person, p / min; P is number of people in room; F is room area, m 2 ;

[0019] Step four, the controller compares current air supply flow Q s with required air supply flow Q n , if Q s = Q n , the valve opening degree is unchanged; if Q s > Q n , the controller outputs a valve opening degree decreasing instruction to the electric actuator, the electric actuator receives the valve opening degree decreasing signal and adjusts the valve opening degree, in the process, the torque sensor outputs the valve torque signal to the controller in real time and the angle sensor outputs the valve opening degree signal to the controller in real time, the controller obtains the current K(θ) by looking up the corresponding relation curve in step one according to the received valve opening degree signal, and then calculates the current air supply flow Q s according to the air supply flow formula, when Q s = Q n , the controller outputs a valve opening degree stopping adjusting signal to the electric actuator, and the electric actuator stops acting;

[0020] if Q s < Q n , the controller outputs a valve opening degree increasing instruction to the electric actuator, the electric actuator receives the valve opening degree increasing signal and adjusts the valve opening degree; in the process, the torque sensor outputs the valve torque signal to the controller in real time and the angle sensor outputs the valve opening degree signal to the controller in real time, the controller obtains the current K(θ) by looking up the corresponding relation curve in step one according to the received valve opening degree signal, and then calculates the current air supply flow Q s according to the air supply flow formula, when Q s = Q n , the controller outputs a valve opening degree stopping adjusting signal to the electric actuator, and the electric actuator stops acting.

[0021] Compared with the prior art, the application has the beneficial effects that:

[0022] (1) The existing VAV BOX generally takes the temperature, humidity and the like in the room as the calculation standard of the air supply volume. The application accurately adjusts the air supply volume of each room according to the number of personnel and the activity intensity in the room, and effectively improves the indoor air quality.

[0023] (2) The air volume measurement technology is integrated into the valve body, and no additional air volume flow meter needs to be installed inside the air supply pipeline, thereby reducing the system complexity and saving the equipment energy consumption.

[0024] (3) The existing VAV BOX is generally equipped with a pitot tube type air speed sensor, and the air volume is measured based on the single-point dynamic pressure. The application measures the air volume by the valve torque, which is obtained by area integration of the valve plate surface pressure, and the measurement accuracy can reach within 4%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the working principle diagram of the air volume measurement and control integrated variable air volume air supply valve and control method of the application;

[0026] Figure 2 is the structural schematic diagram of the air volume measurement and control integrated variable air volume air supply valve integrated into the variable air volume air conditioning system of the application;

[0027] Figure 3 is the principle schematic diagram of the air volume measurement and control integrated variable air volume air supply valve based on the valve torque measurement of the application. DETAILED DESCRIPTION

[0028] The technical solutions of the application will be described clearly and completely below with reference to the drawings. It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concept of the application, and the diagrams do not show the number, shape and size of the components in the actual implementation, but the type, number and proportion of the components in the actual implementation can be randomly changed, and the component layout type can be more complex.

[0029] The air volume measurement and control integrated variable air volume air supply valve of the application comprises a torque valve, and the torque valve can be an existing torque valve. A torque sensor 1 and an angle sensor 2 are respectively installed on the valve shaft of the torque valve. An electric actuator 4 is installed on the valve body of the torque valve, the execution output end of the electric actuator 4 is connected with the valve shaft of the torque valve, the electric actuator can adopt an existing structure and is commercially available. The signal output end of the torque sensor 1 and the angle sensor 2 is connected with the signal input end of a controller 3, and the signal output end of the controller 3 is connected with the signal input end of the electric actuator 4.

[0030] The application provides a control method of the air volume measurement and control integrated variable air volume air supply valve, comprising the following steps:

[0031] Step 1: Using the valve opening angle θ as the abscissa and the valve torque flow coefficient K(θ) as the ordinate, establish the corresponding curve between the torque flow coefficient K(θ) of the torque valve and the opening angle θ, and store it in the controller. The specific process is as follows: Through valve experiments or CFD numerical simulations, given any inlet wind speed, measure the valve torque N and the ratio β of the airflow area to the pipe area at different valve opening angles, and substitute them into formula (4) to establish the relationship curve between the valve opening angle θ and the valve torque flow coefficient K(θ). The torque flow coefficient K(θ) is only related to the opening angle of the torque valve. This correspondence needs to be obtained indirectly through the valve torque and the ratio of the airflow area to the pipe area, but it is not related to the wind speed in the pipe.

[0032]

[0033] Where K(θ) is the valve torque-flow coefficient; θ is the valve opening angle; Q s This is the current air supply flow rate, in meters (m). 3 / h; α is the ratio of the projected area of ​​the valve plate in the vertical airflow direction to the area of ​​the pipe when the torque valve is closed; ρ is the air density, kg / m³ 3 β is the ratio of the airflow area of ​​the torque valve to the pipe area; A1 is the cross-sectional area of ​​the pipe where the torque valve is installed, in meters. 2 N is the valve torque value of the torque valve, Nm;

[0034] Step 2: Measuring airflow based on valve torque and valve opening angle of the torque valve. The specific process is as follows: Controller 3 reads the valve torque value N output by torque sensor 1 and the opening angle value θ of the torque valve output by angle sensor 2, and then calculates the current airflow in the room using the following formula:

[0035]

[0036] The derivation of formulas (4) and (5) is as follows:

[0037] Taking a standard flat-plate vane non-eccentric torque valve as an example, at a certain opening angle, the pressure distribution on the front and rear surfaces of the torque valve plate is as follows: Figure 3 As shown.

[0038] For incompressible fluids, according to Bernoulli's equation, we have

[0039]

[0040] Among them, P m It is hydrostatic pressure, Pa; v mρ is the fluid velocity, in m / s, where m = 1 or 2. When m = 1, it represents the location of any cross-section of the fluid pipeline upstream of the torque valve; when m = 2, it represents the location of any cross-section of the fluid pipeline downstream of the torque valve. ρ is the fluid density, in kg / m³. 3 ξ f The friction coefficient is related to factors such as the fluid flow state (e.g., laminar or turbulent), Reynolds number, and pipe roughness. Under turbulent conditions, the friction coefficient is usually calculated using empirical formulas (e.g., the Colebrook equation) or graphs (e.g., the Moody diagram), while under laminar conditions, it is mainly related to the fluid viscosity and the pipe diameter. This coefficient is used to modify the Bernoulli equation and reflects the energy loss caused by friction during fluid flow.

[0041] According to formula (6), the air volume flow rate through the torque valve can be expressed as:

[0042]

[0043] Where A1 is the cross-sectional area of ​​the pipe on which the torque valve is installed, m 2 A2 is the cross-sectional area of ​​the fluid pipeline downstream of the torque valve, in meters. 2 .

[0044] A2=A1-α·cosθ·A1 (8)

[0045] Where α is the ratio of the projected area of ​​the valve plate in the vertical airflow direction to the area of ​​the pipe when the torque valve is closed, and α is usually < 1; θ is the opening angle of the torque valve, in °.

[0046] There are two fluid pipeline sections before and after the torque valve, and their average pressure is equal to the average pressure on the front and rear surfaces of the torque valve plate. Therefore, according to formula (7), we can obtain that...

[0047]

[0048] Where A1' is the area of ​​the fluid pipeline cross-section where the average pressure on the front surface of the torque valve plate is equal to that of the average pressure on the front surface of the torque valve plate, m 2 A2' is the area of ​​the fluid pipeline cross-section where the average pressure on the rear surface of the torque valve plate is equal to that of the average pressure on the rear surface of the torque valve plate, in meters. 2 ; It is the average pressure on the front surface of the torque valve plate, in Pa; It is the average pressure on the rear surface of the torque valve plate, in Pa.

[0049] Dividing equation (7) by equation (9) yields

[0050]

[0051] Wherein, k(θ) is defined as (P1-P2) and The ratio,

[0052]

[0053] Since the cross-sectional position cannot be accurately obtained, k(θ) cannot be theoretically obtained. Changes in geometric features at different torque valve opening angles result in different k(θ).

[0054] Substitute formula (10) into formula (7) and let get

[0055]

[0056] When the valve shaft of the torque valve is located at the center of the valve plate, the valve torque is caused by the uneven pressure distribution on the valve surface, as shown in formulas (13) and (14).

[0057]

[0058] N = M1 + M2 (14)

[0059] Where x is the coordinate value perpendicular to the valve axis of the torque valve, and m; A(x) is the coordinate value of the pressure center point of the torque valve plate, in meters; A(x) is the area of ​​the torque valve plate on one side, with the valve shaft as the boundary, in meters. 2 P(x) is the pressure at the x-coordinate of the torque valve plate surface, Pa; D is the length of the torque valve plate perpendicular to the valve shaft, m; M1 is the average pressure on the surface of the torque valve plate, Pa; M2 is the torque generated by the uneven pressure distribution on the front surface of the torque valve plate, Nm; M3 is the torque generated by the uneven pressure distribution on the rear surface of the torque valve plate, Nm; dx is the differential calculation of x.

[0060] The force acting on the torque valve is equal to the valve plate area multiplied by the average pressure difference between the front and rear surfaces of the valve disc, i.e.

[0061]

[0062] Define an equivalent torque distance ΔB:

[0063]

[0064] From formulas (15) and (16), the conversion formula between the average pressure difference between the front and rear surfaces of the torque valve plate and the total torque of the torque valve can be obtained as follows:

[0065]

[0066] Define valve torque-flow coefficient The air volume Q can be obtained. s The expression relating the torque valve torque N and the opening angle θ is shown in Equation (18);

[0067]

[0068] K(θ) needs to be determined in advance through valve experiments or CFD numerical simulations. It is only related to the opening angle of the torque valve and is independent of the air velocity in the pipe. According to formula (18), the formula for calculating K(θ) is shown in formula (19).

[0069]

[0070] Since ordinary non-eccentric torque valves have relatively small torque, this invention preferably uses a torque valve with an irregularly shaped valve plate, such as... Figure 1 As shown, its torque can be increased by 4-5 times compared to ordinary non-eccentric torque valves.

[0071] Step 3: Controller 3 receives the indoor particulate matter concentration value output by the particulate matter concentration sensor installed in the room, and calculates the required air supply flow rate Q in the room through the mass balance equation. n In this context, it is assumed that the particulate matter is uniformly mixed within the room.

[0072] The mass balance equation is as follows:

[0073] VdC i =Q n C0·(1-e)dt+GVdt-Q e C i dt (20)

[0074] Where V is the room volume, m 3 C i This is the indoor particulate matter concentration value, p / m³. 3 C0 is the particulate matter concentration in the supply air, p / m³. 3 Q n It is the required air supply flow rate, m 3 / h;Q e It is the exhaust airflow, m 3 / h; e is the filter efficiency in the air handling unit, with a value of 99.9985%; dC i It is for C i Differential; dt is the differential with respect to t; G is the indoor average particle generation rate, p / (m 3 .h); can be calculated according to formula (21):

[0075]

[0076] Where q refers to the dust emission rate of the decorative materials, p / (min.m2 ), which can usually be ignored; H is the room height, m; q' is the particle generation rate of a person, which has different definitions depending on the number of people and their activity intensity in different application scenarios. You can find relevant literature and refer to relevant experimental results. For example, in a biological cleanroom, each person generates 50,000-180,000 particles per minute (Ref: Zhang et al. Dynamic emission rates of human activity in biological cleanrooms. Building and Environment, 226(2022), Article 109777, p / min; P is the number of people in the room; F is the room area, m. 2 .

[0077] In this step, the required air volume in the room is determined based on the number of people and the concentration of particulate matter generated by their activity intensity.

[0078] Step 4: The controller 3 compares the current air supply flow rate Q. s air supply flow rate Q n If Q s =Q n The valve opening remains unchanged; if Q s >Q n This indicates that the air supply volume is redundant and the valve opening needs to be reduced. Controller 3 outputs a command to reduce the valve opening to electric actuator 4. Electric actuator 4 receives the "reduce valve opening" signal and adjusts the valve opening. During this process, torque sensor 1 outputs a valve torque signal to controller 3 in real time, and angle sensor 2 outputs a valve opening signal to controller 3 in real time. Controller 3 obtains the current K(θ) based on the received valve opening signal by looking up the corresponding relationship curve in step one, and then calculates the current air supply flow rate Q according to the air supply flow rate formula. s When Q s =Q n The controller 3 outputs a stop adjustment valve opening signal to the electric actuator 4, and the electric actuator 4 stops operating;

[0079] If Q s <Q nThis indicates insufficient air supply, requiring a larger valve opening. Controller 3 outputs a command to increase valve opening to electric actuator 4. Electric actuator 4 receives the "increase valve opening" signal and adjusts the valve opening. During this process, torque sensor 1 outputs a valve torque signal to controller 3 in real time, and angle sensor 2 outputs a valve opening signal to controller 3 in real time. Controller 3 obtains the current K(θ) based on the received valve opening signal by referring to the corresponding curve in step one, and then calculates the current air supply flow rate Q according to the air supply flow rate formula. s When Q s =Q n The controller 3 outputs a stop adjustment valve opening signal to the electric actuator 4, and the electric actuator 4 stops operating.

[0080] For installation instructions on this device in specific applications, please refer to [link / reference]. Figure 2 Taking a variable air volume (VAV) air conditioning system with n terminals as an example, this invention can be installed at the end of each branch line to replace the traditional VAV box. It can precisely adjust the air supply volume of each room according to the number of people in the room and their activity intensity, effectively improving indoor air quality.

[0081] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A variable air volume supply valve integrating air volume measurement and control, comprising a torque valve, characterized in that: A torque sensor (1) and an angle sensor (2) are respectively installed on the valve shaft of the torque valve; an electric actuator (4) is installed on the valve body of the torque valve. The execution output end of the electric actuator is connected to the valve shaft of the torque valve. The signal output ends of the torque sensor and the angle sensor are connected to the signal input end of the controller (3). The signal output end of the controller is connected to the signal input end of the electric actuator.

2. The integrated variable air volume valve for air volume measurement and control according to claim 1, characterized in that: The valve plate of the torque valve has an irregular structure.

3. A control method for an integrated variable air volume (VAV) air supply valve with integrated air volume measurement and control, used in the integrated VAV air supply valve with integrated air volume measurement and control as described in claim 1 or 2, characterized in that... Includes the following steps: Step 1: Using the valve opening angle value θ as the abscissa and the valve torque flow coefficient K(θ) as the ordinate, establish the corresponding relationship curve between the torque flow coefficient K(θ) of the torque valve and the opening angle value θ, and store it in the controller. The calculation formula for K(θ) is as follows; Where K(θ) is the valve torque-flow coefficient; θ is the valve opening angle; Q s This is the current air supply flow rate, in meters (m). 3 / h; α is the ratio of the projected area of ​​the valve plate in the vertical airflow direction to the area of ​​the pipe when the torque valve is closed; ρ is the air density, kg / m³ 3 β is the ratio of the airflow area of ​​the torque valve to the pipe area; A1 is the cross-sectional area of ​​the pipe where the torque valve is installed, in meters. 2 N is the valve torque value of the torque valve, Nm; Step 2: Measuring airflow based on valve torque and valve opening angle of the torque valve. The specific process is as follows: The controller reads the valve torque value N output by the torque sensor and the valve opening angle value θ output by the angle sensor, and then calculates the current airflow in the room using the following formula: Step 3: The controller receives the indoor particulate matter concentration value output by the particulate matter concentration sensor installed in the room, and calculates the required air supply flow rate Q in the room using the mass balance equation. n In this case, it is assumed that the particulate matter is uniformly mixed within the room. The mass balance equation is as follows: VdC i =Q n C0·(1-e)dt+GVdt-Q e C i dt Where V is the room volume, m 3 C i This is the indoor particulate matter concentration value, p / m³. 3 C0 is the particulate matter concentration in the supply air, p / m³. 3 Q n It is the required air supply flow rate, m 3 / h;Q e It is the exhaust airflow, m 3 / h; e is the filter efficiency in the air handling unit; dC i It is for C i Differential; dt is the differential with respect to t; G is the indoor average particle generation rate, p / (m 3 .h); Where q refers to the dust emission rate of the decorative materials, p / (min.m 2 H is the room height (m); q' is the particle generation rate per person (p / min); P is the number of people in the room; F is the room area (m²). 2 ; Step 4: The controller compares the current air supply flow rate Q. s air supply flow rate Q n If Q s =Q n The valve opening remains unchanged; if Q s >Q n The controller outputs a command to the electric actuator to reduce the valve opening. The electric actuator receives the signal and adjusts the valve opening. During this process, the torque sensor outputs a valve torque signal to the controller in real time, and the angle sensor outputs a valve opening signal to the controller in real time. The controller obtains the current K(θ) based on the received valve opening signal by looking up the corresponding curve in step one, and then calculates the current airflow rate Q according to the airflow rate formula. s When Q s =Q n The controller outputs a stop signal to the electric actuator to adjust the opening of the damper, and the electric actuator stops operating. If Q s <Q n The controller outputs a command to the electric actuator to increase the valve opening. The electric actuator receives the signal to increase the valve opening and adjusts the valve opening. During this process, the torque sensor outputs a valve torque signal to the controller in real time, and the angle sensor outputs a valve opening signal to the controller in real time. The controller obtains the current K(θ) based on the received valve opening signal by looking up the corresponding curve in step one, and then calculates the current airflow Q according to the airflow formula. s When Q s =Q n The controller outputs a stop signal to the electric actuator to adjust the opening of the damper, and the electric actuator stops operating.

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