KR20080041365A - System and method for measuring quantity of air in ventilation duct - Google Patents

Abstract

A system and a method for measuring air flux in a ventilation duct are provided to increase accuracy of the air flux in low velocity by removing back pressure. A system for measuring air flux in a ventilation duct(10) includes a nozzle(27), third and forth tubes(25c,25d), a differential pressure sensor(28), a suction fan(12), a level meter(17), and a leveling unit. The ventilation duct is coupled to a fixing unit(14) with a hinge, having an inlet and an outlet on both sides for allowing air to flow in and out. The nozzle is attached inside the duct and has a central part protruding for narrowing air passing area. The third and forth ring tubes are installed on the nozzle for measuring pressure of air flux. The differential pressure sensor calculates the difference between pressures measured by the ring tubes. The suction fan is installed in the rear of the nozzle and sucks air. The level meter and the leveling unit are attached to the ventilation duct for controlling horizontality of the ventilation duct.

Description

System and method for measuring quantity of air in ventilation duct}

1 is a block diagram showing an embodiment of the air flow rate measuring apparatus according to the present invention,

2a and 2b is a state diagram showing the operating state of the level gauge according to the invention,

3 is a flow chart showing the air flow rate measuring method according to the present invention,

Figure 4 is a block diagram showing an embodiment of a conventional air flow rate measuring device.

<Description of the symbols for the main parts of the drawings>

10: duct 11: flexible tube

12: suction fan 12a: blade

13: drive motor 14: fixed end

15 Bracket 16: Hinge pin

17: level 18: electrolyte liquid

19: air bubble 20: ammeter

21: rack gear 22: pinion

23 screen member 24 honeycomb member

25a to 25d: first to fourth ring tubes

26: connection tube 27: nozzle

28: differential pressure sensor 29: shutter

The present invention relates to a flow rate measuring device and method of the natural ventilation duct, and more particularly, the flexible tube is connected to the end of the natural ventilation duct, the screen member and the honeycomb member can be installed at the flexible tube end to maintain the flow uniformly The air volume is measured using the pressure difference between the front of the nozzle and the neck inside the duct, and by measuring several points using the ring tube, the average value can be measured, and the level gauge, the driving motor and the gear means The present invention relates to a flow rate measuring device and a method of a natural ventilation duct to improve the measurement accuracy in the low speed region by adjusting the horizontal.

Generally, the air flow measurement of the blower or the duct uses a pitot pressure pipe or an anemometer. At this time, insert the measuring instrument into the duct so that it is perpendicular to the direction of air flow.

However, it is difficult to maintain more than 1 minute for each measuring hole without changing the position of up, down, left and right, and it is not possible to visually check in which direction or which position when the sensor part of the measuring instrument is inserted into the duct. Since it is difficult to follow, the precision of a measured value falls.

In particular, as shown in FIG. 4, there is a problem in that a back pressure formed in the pressure measuring nozzle unit 100 is transferred to the ultra low speed flow to generate a pressure loss.

The present invention has been made in view of the above point, including the flexible tube installed at the end of the natural ventilation duct, the screen member and the honeycomb member mounted on the flexible tube end to maintain a uniform flow, and then inside the duct The air volume is measured using the pressure difference between the front of the nozzle and the neck, but by measuring several points by using the ring tube, the average value can be measured, and the level of the duct is adjusted by using a level gauge, a driving motor, and a gear means. It is an object of the present invention to provide a device and a method for measuring the airflow of natural ventilation ducts to improve measurement accuracy in the field.

In the present invention for achieving the above object, in the air flow measurement device of the natural ventilation duct,

A natural ventilation duct having a lower end hinged to the fixed end and having inlets and outlets formed at both ends thereof to allow air to flow therein; A nozzle attached to the inside of the duct and having a central portion protruding from the air so as to narrow a cross-sectional area of air; Third and fourth ring tubes circumferentially installed at the center and the front of the nozzle for pressure measurement; A differential pressure sensor for calculating a difference in pressure measured in the ring tube; A suction fan installed at the rear of the nozzle to suck air; And a level gauge and a horizontal adjusting means attached to the duct to adjust the level of the duct.

In a preferred embodiment, a flexible tube is introduced through the inlet and the other end is attached to the front end of the duct; And first and second ring tubes installed in the circumferential direction for pressure measurement at the inlet and the other end of the flexible tube.

In a more preferred embodiment, the screen member is installed at the front end of the duct or the rear end of the flexible tube, and a plurality of mesh holes formed therein, and a honeycomb member installed at the rear of the screen member and formed with a plurality of hexagonal holes therein. Characterized in that configured.

In addition, the first to fourth ring tube has a body formed in the circumferential direction, a plurality of connection tubes are formed in the radial direction from the body, the pressure measurement is that the average value by measuring the pressure in a plurality of directions in the connection tube It features.

In addition, a plurality of rotating shafts are installed in parallel on the cross-section of the duct and attached to both sides about the rotating shaft to adjust the amount of air flowing in the duct in the low speed region at the rear of the suction fan, and the rotary blades. It characterized in that the shutter consisting of a rotary wing control means for adjusting the opening and closing amount is installed.

In addition, the level gauge is filled with an electrolyte liquid therein, the air bubble is formed on the upper portion to determine whether the duct is horizontal, the electrode is disposed in the center of the level meter, the ammeter is applied to the electrode and the level meter It is characterized in that it is electrically connected.

In addition, the horizontal adjustment means is a rack gear attached to the lower portion of the duct so that the front end portion of the duct is rotatable, and the pinion for engaging the rack gear to move the rack gear in the vertical direction, and the pinion is connected It characterized in that it comprises a drive motor for driving the pinion.

In addition, the step of measuring the pressure (P1, P2) through the first and second ring tubes installed in the inlet and the other end of the flexible tube; Calculating a pressure difference between P1 and P2 measured in the step by a differential pressure sensor; Determining whether the pressure difference is close to zero, and adjusting a flow rate by driving a suction fan until the pressure difference is close to zero; Measuring the voltage V through a level meter; Maintaining the level of the duct using the level gauge; Calculating pressure differences between P3 and P4 by measuring pressures P3 and P4 through third and fourth ring tubes provided at the front and center of the nozzle when the duct is in a horizontal state; And measuring the flow rate v and the air volume Q by using the calculated pressure difference using the following equation.

, Q=(단면적)×(유속), 상기 α는 베르누이방정식에서 계산하여 적용하기 위한 교정계수이고, ρ는 공기밀도이다.

, Q = (cross-sectional area) × (flow rate), α is a calibration coefficient for calculation and application in the Bernoulli equation, and ρ is the air density.

In addition, it is determined whether the pressure difference is close to zero, and the suction fan is driven until the pressure difference is close to zero, but at a low speed (1-2 m / sec), the flow rate is controlled by reducing the aperture ratio of the shutter. do.

In addition, the horizontal maintenance step is filled with the electrolyte liquid therein, the level gauge with an air bubble formed on top to determine whether the duct is horizontal, the ammeter installed in the level meter, the front end of the duct in the vertical direction The rack gear is attached to the lower portion of the duct so as to be rotatable, a pinion which meshes with the rack gear to move the rack gear in the up and down direction, and a driving motor connected to the pinion to drive the pinion. It is characterized in that for driving the drive motor until the air bubbles of the system is located in the center.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing an embodiment of the air flow rate measuring apparatus according to the present invention.

The present invention has a main point in that the amount of air flow in the duct 10 can be more accurately measured.

The present invention provides a natural ventilation duct 10, a flexible tube 11 installed at the end of the natural ventilation duct 10 to suck air, a suction fan 12 installed inside the natural ventilation duct 10 and natural Installed in the lower portion of the ventilation duct 10 is configured to include a horizontal holding means for maintaining the duct in the horizontal direction and the drive motor (13).

The natural ventilation duct 10 (hereinafter, referred to as a duct) has a space through which air flows, and a lower end of one side of the duct 10 has a bracket 15 and a hinge pin (installed at the fixed end 14). 16 is coupled by the front end of the duct 10 is rotatable in the vertical direction.

The upper part of the duct 10 is provided with a level gauge 17 in the longitudinal direction, and the level meter 17 is filled with an electrolyte liquid 18 so that the duct 10 cannot be leveled. Air bubbles 19 formed on the upper part of 17) are biased in one direction and can be viewed horizontally.

An electrode is attached to the center upper portion of the level gauge 17, and an ammeter 20 is electrically connected to one side of the electrode and the level meter 17.

In addition, the drive motor 13 is installed on the fixed end 14 at regular intervals from the bracket, the rack gear 21 is attached to the lower portion of the duct 10 in the vertical direction to keep the duct 10 horizontal. And a pinion 22 which is engaged with the rack gear 21 and rotated by the rotational force of the drive motor 13.

At this time, the pinion 22 is installed on the drive motor shaft.

Flexible tube 11 is installed at the front end of the duct 10, the flexible tube 11 has a certain amount of air flows inside the tube body that can move the direction freely, and the air in the front end of the tube body It consists of an inlet part surrounded by a solid material to keep the inflow direction.

At the rear end of the flexible tube 11, a screen member 23 having a plurality of mesh balls formed therein, and a honeycomb formed at a rear of the screen member and having a plurality of hexagonal holes formed therein. It is configured to include a member. At this time, the screen member 23 and the honeycomb member 24 are installed in a direction perpendicular to the air flow.

In addition, first and second ring tubes 25a and 25b for static pressure measurement are installed at the front and rear ends of the flexible tube 11, and the first and second ring tubes 25a and 25b are flowed. The connection tube 26 is connected through eight through holes formed in the tube inlet to remove the directivity of the tube.

The average pressures P1 and P2 are measured by averaging eight measured values measured through the connection tube 26.

A nozzle 27 is installed inside the duct 10, and the nozzle 27 is attached to the upper and lower inner wall surfaces of the middle of the duct 10, respectively, and the middle of the nozzle 27 faces each other inside. The cross-sectional area through which the air passes through the direction is wider in front of the nozzle 27, and narrows toward the middle, and widens again toward the rear.

In this case, third and fourth ring tubes 25c and 25d are installed at the front and middle portions of the nozzle 27, respectively, and P3 and P4 are measured using the nozzles 27, and the pressure difference in the flexible tube 11 is measured. The differential pressure sensor 28 is provided at the fixed end 14 to determine the pressure difference P3-P4 at the P1-P2 and the nozzle 27.

A suction fan 12 for sucking air is installed at the rear of the nozzle 27, and the suction fan 12 has a plurality of blades 12a installed in a radial direction about a central axis to smoothly flow air. Let's do it.

The suction fan 12 is configured to include a fan motor for rotating the central axis, and a support for supporting the fan motor in the upper and lower parts.

In addition, the rear of the suction fan 12 is difficult to adjust the flow rate of the air only by adjusting the rotational speed of the suction fan 12 in the low speed section, so that the shutter 29 is installed to improve this, the shutter 29 is air A plurality of rotating shafts are installed in parallel on the flowing cross-section and attached to both sides around the rotating shaft, and rotating wing adjusting means for rotating the rotating shaft to adjust the blades by a motor or the like.

Referring to the operation state and the air flow measurement method of the air flow rate measuring device of the natural ventilation duct 10 according to the present invention as described above are as follows.

Figure 2a and Figure 2b is a state diagram showing the operating state of the level gauge according to the present invention, Figure 3 is a flow chart showing the air flow measurement method according to the invention.

First, air is introduced through the inlet of the flexible tube 11, and the air introduced into the flexible tube 11 passes through the mesh hole of the screen member 23 and the hexagonal hole of the honeycomb member 24. It becomes uniform.

Here, the average pressure P1 is measured using the first ring tube 25a provided at the inlet of the flexible tube 11, and the average is measured using the second ring tube 25b provided at the rear end of the flexible tube 11. Measure the pressure P2.

In addition, using the differential pressure sensor 28 to calculate the front and rear pressure difference (P1-P2 = ΔP1) of the flexible tube (11).

The axial suction fan 12 is rotated to generate flow until ΔP1 is zero.

On the other hand, at an extremely low flow rate of 1 to 2 m / s, it is difficult to adjust the flow rate only by adjusting the rotational speed of the suction fan 12, thereby adjusting the flow rate while adjusting the opening rate of the shutter 29.

After that, when the flow of air is stabilized, the level of the duct 10 is adjusted using the level gauge 17. That is, the air bubbles 19 are collected at the electrode (center) position to drive the driving motor 13 until the voltage V of the ammeter 20 approaches zero (0).

As the drive motor 13 is driven, the pinion 22 is rotated so that the rack gear 21 moves in the vertical direction, and the rack gear 21 moves the front end of the duct 10 in the vertical direction. (10) can be kept horizontal.

After the horizontal flow of the duct 10 and the flow rate inside the duct 10 is stabilized, the pressures P3 and P4 of the front of the nozzle 27 and the neck (center) of the nozzle 27 are measured and the differential pressure sensor 28 is measured. Calculate ΔP2 (= P3-P4) using.

Using the pressure difference in the nozzle 27, the flow velocity v inside the duct 10 can be obtained by the following equation.

In this case, α is a correction factor for calculating and applying the Bernoulli equation, ρ is the air density.

The air flow rate can be obtained by substituting v value obtained in Equation 1 into general engineering formula of 'flow rate = cross-sectional area (A) x flow rate (v)'.

By the operation state and the air flow measurement method of the air flow measurement device as described above, the present invention can improve the accuracy when measuring the air flow in the low speed region because the back pressure does not work, and measure the flow on the wall surface of the duct 10 by using a ring tube Since several points are measured, the average value can be measured.

By employing the screen member 23 and the honeycomb member 24, the oil quality becomes uniform, and the adoption of the nozzle 27 improves the measurement accuracy in the low speed region.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

As described above, according to the air flow rate measuring apparatus and method of the natural ventilation duct according to the present invention, since the back pressure does not work, it is possible to improve the accuracy when measuring the air flow in the low speed region, the flow is measured on the duct wall and ring tube By measuring several points, the average value can be measured.

By adopting the screen member and the honeycomb member, the oil quality becomes uniform, and the adoption of the nozzle improves the measurement accuracy in the low speed region.

Claims (10)

In the air flow rate measuring device of the natural ventilation duct, A natural ventilation duct 10 having a lower end hinged to the fixed end 14 and having inlets and outlets at both ends thereof so as to allow air to flow therein; A nozzle (27) attached to the inside of the duct (10) and protruding from the center portion to narrow the passage cross-sectional area of air; Third and fourth ring tubes (25c, 25d) installed in the circumferential direction for pressure measurement at the center and the front of the nozzle (27); A differential pressure sensor 28 for calculating a difference in pressure measured in the ring tube; A suction fan 12 installed at the rear of the nozzle 27 to suck air; A level gauge 17 and horizontal adjusting means attached to the duct 10 to adjust the level of the duct 10; Air flow rate measuring device of the natural ventilation duct, characterized in that configured to include. The method according to claim 1, Air is introduced through the inlet, and a flexible tube 11 whose other end is attached to the front end of the duct 10; First and second ring tubes (25a, 25b) installed in the circumferential direction for pressure measurement at the inlet and the other end of the flexible tube (11); Air flow rate measuring device of the natural ventilation duct, characterized in that configured to include. The method according to claim 1 or 2, Honeycomb, which is installed at the front end of the duct 10 or the rear end of the flexible tube 11, the screen member 23 formed with a plurality of mesh holes therein, and the hexagonal holes formed inside the screen member with a plurality of hexagonal holes formed therein. Air flow measurement device of the natural ventilation duct, characterized in that configured to include a member (24). The method according to claim 2, The first to fourth ring tubes are formed in the circumferential direction, and a plurality of connecting tubes 26 are formed in the radial direction from the body, and the pressure measurement is to measure the pressure in a plurality of directions in the connecting tube 26 Air flow rate measuring device of the natural ventilation duct, characterized in that the average value. The method according to claim 4, In the rear of the suction fan 12, in order to control the amount of air flowing in the duct 10 in the low speed region, a plurality of rotating shafts are installed in parallel on the cross section of the duct 10 and attached to both sides about the rotating shaft. Air flow measuring device of the natural ventilation duct, characterized in that the shutter and a shutter 29 consisting of a rotary wing control means for adjusting the opening and closing of the rotary blades. The method according to claim 1 or 2, The level gauge 17 is filled with an electrolyte liquid 18 therein, and an air bubble 19 is formed at an upper portion to determine whether the duct 10 is in a horizontal state, and a central portion of the level gauge 17 is provided. The electrode is disposed in, the ammeter (20) is the air flow rate measuring apparatus of the natural ventilation duct, characterized in that electrically connected to the electrode and the level meter (17). The method according to claim 1 or 2, The horizontal adjustment means is a rack gear 21 attached to the lower portion of the duct 10 so that the front end portion of the duct 10 can rotate in the up and down direction, the rack gear 21 in engagement with the rack gear 21 It characterized in that it comprises a pinion (22) for moving in the vertical direction, and a drive motor (13) connected to the pinion (22) to drive the pinion (22). In the air flow rate measuring method using the apparatus of claim 2, Measuring pressure (P1, P2) through first and second ring tubes (25a, 25b) provided at the inlet and the other end of the flexible tube (11); Calculating the pressure difference between P1 and P2 measured in the above step by the differential pressure sensor 28; Determining whether the pressure difference is close to zero, and adjusting the flow rate by driving the suction fan 12 until the pressure difference is close to zero; Measuring the voltage V through a level meter 17; Maintaining the level of the duct (10) using the level gauge (17); In the above step, when the duct 10 is in a horizontal state, the pressures P3 and P4 are measured by measuring the pressures P3 and P4 through the third and fourth ring tubes 25c and 25d provided at the front and center of the nozzle 27. Calculating a difference; Measuring the flow rate v and the air volume Q using the calculated pressure difference using the following equation; Air flow measurement method of the natural ventilation duct, characterized in that comprises a.

, Q = (cross-sectional area) × (flow rate), α is a calibration coefficient for calculation and application in the Bernoulli equation, and ρ is the air density. The method according to claim 8, It is determined whether the pressure difference is close to zero, and the suction fan 12 is driven until the pressure difference is close to zero, but at a low speed (1-2 m / sec), the opening ratio of the shutter 29 is reduced to adjust the flow rate. Air flow measurement method of the natural ventilation duct, characterized in that. The method according to claim 8 or 9, The leveling step is filled with an electrolyte liquid 18 therein, a level gauge 17 having an air bubble 19 formed thereon to determine whether the duct 10 is in a horizontal state, and the level gauge 17 And a rack gear 21 attached to the lower portion of the duct 10 so that the front end portion of the duct 10 is rotatable in the vertical direction, and the rack gear 21 is engaged with the Air of the level gauge 17 using a pinion 22 that moves the rack gear 21 in the up and down direction, and a drive motor 13 connected to the pinion 22 to drive the pinion 22. Air flow measurement device of the natural ventilation duct, characterized in that for driving the drive motor 13 until the drop (19) is located in the center.

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