CN115854533A

CN115854533A - Air outlet pipeline and air outlet uniformity adjusting method thereof

Info

Publication number: CN115854533A
Application number: CN202211056449.0A
Authority: CN
Inventors: 黄荣芳
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-08-31
Filing date: 2022-08-31
Publication date: 2023-03-28
Also published as: TWI814319B; CN115854457A; TW202312001A; TWI785928B; TW202311678A

Abstract

The application relates to a ventilation and heat dissipation method, and provides an air outlet pipeline for being installed in a factory building, wherein the air outlet pipeline is divided into a plurality of gradually-reduced sections from an upstream end to a downstream end, and the sections are respectively provided with at least one air outlet so as to provide a plurality of downward blowing air flows. The method for adjusting the air outlet uniformity of the air outlet pipeline mainly comprises the following steps: the method comprises the steps of designing at least one air outlet pipeline in height and air outlet geometry, designing at least one air outlet pipeline in geometry, and configuring and designing at least one air outlet pipeline position of a factory building so as to reduce the temperature and the concentration of pollutants in the factory building.

Description

Air outlet pipeline and air outlet uniformity adjusting method thereof

Technical Field

The present application relates to an air outlet duct and a method for adjusting an air outlet uniformity thereof, and more particularly to an air outlet duct and a method for adjusting an air outlet uniformity thereof capable of effectively reducing a temperature and a concentration of pollutants in a factory.

Background

For a general factory building, if the number of operators in the building is large, the machine generates heat and the exhausted hot air cannot be removed outside the building, and the heat will cause the temperature in the building to rise. When low dust needs to be kept in a factory building, if a common air suction and ventilation method is used, the dust can be easily sucked into a room from an open window and a door.

For example: for the factory building for manufacturing the plastic bags, a heating machine is arranged in the factory building, and because the low-dust state is required to be kept so as not to be adhered to the plastic bags, all windows are closed, and only louvers are arranged above the walls, so that high temperature in the factory building is caused, individual plastic bags are not easy to separate, and dust is difficult to avoid. In a factory building for manufacturing the sneakers and the belts, a heating machine is arranged in the workshop, and the heating machine needs to be kept in a low-dust state so as to avoid being stuck on the sneakers and the belts during gluing and pressing. All windows of left and right side walls are closed in the factory, but in order to ventilate and avoid high temperature in the factory, can install many suction fans at the rear end window, and open the door and window of front end wall, but except near the door and window of front end wall is windy, most regional nearly calm in the factory, so more can install many "relay fans" in the factory above, the intuition is so that can make the smooth and easy suction fan that flows toward the rear end window from the door and window of front end wall of air current, in a large amount of dusts can be followed the door and window of front end wall and is inhaled the factory building in the result, still high temperature in the factory building. If the filter screen is installed on the window or the door to filter the dust, the pressure loss caused by the blockage of the filter screen can greatly reduce the flow of the axial fan and increase the energy consumption, thereby not only consuming time and labor in cleaning the filter screen and maintaining, but also not effectively blocking the dust from entering the plant. Therefore, a filter screen is arranged on each open window and door, and a choke point is really difficult in practice.

In addition, to deal with the above problems of "hot" and "dust", a "dilution pressurization method" is often used, in which a fan supplies filtered "cold", "warm" or "normal temperature" clean air into the plant, the clean air is mixed (diluted) with the original air in the room, and the opening of the window is adjusted, so that when the air flows over the opening of the window, sufficient pressure loss (resistance) is caused to prevent the dust from flowing into the plant, and the temperature in the plant, even the concentration of pollutants, can be reduced. However, the basic principle of the dilution method in the traditional ventilated textbook and handbook is basically assumed as follows: the spatial distribution of the stain concentration of the dirt in the room at any instant in time is "uniform". But cannot be applied in the complex situation of the actual factory.

Disclosure of Invention

In view of the above, the present inventors have made many years of experience and continuous research and development to provide a structure different from the prior art and to improve the above-mentioned disadvantages.

An object of this application is solving current ventilation cooling technique in the actual application, still can't effectively reduce the problem of temperature, pollutant concentration in the factory building, and can provide an air-out pipeline and air-out degree of consistency adjustment method thereof to reduce the temperature and the pollutant concentration in the factory building.

To achieve the above object, the air outlet duct of the present application is installed in a factory building, the air outlet duct has an upstream end and a downstream end, the air outlet duct is divided into a plurality of gradually-reduced sections from the upstream end to the downstream end, and each of the plurality of sections has at least one air outlet for outputting a downward blowing airflow.

The utility model provides an air-out degree of consistency adjustment method of air-out pipeline, air-out pipeline wherein supplies to install in a factory building, and the factory building includes a roof and locates the roof below and the several side wall that sets up in proper order in succession, and a room space is enclosed to common frame of roof and several side wall, and room space top has at least one air-out pipeline in order to provide several blow down and flows, has at least one window that supplies the exhaust on at least one side wall. The method for adjusting the air outlet uniformity of the air outlet pipeline comprises the following steps: A. at least one air outlet pipeline height and air outlet geometric design step, which uses a database to select and adjust the minimum pipeline installation height h and air outlet length d of the at least one air outlet pipeline _j Width w _j S pitch ratio of _j /d _j And the number N of air outlets _j Average wind speed u of air outlet _j (ii) a B. At least one air outlet pipeline geometric design step, which firstly uses the fluid mechanics basic principle to make preliminary design, then uses CFD computer program to calculate and design at least one air outlet pipeline geometric dimension (long Lduct, wide Wduct and high Hduct) so as to make the maximum wind speed or flow unevenness of several air outlets reach satisfactory low value; c, at least one air outlet pipeline position configuration design step of the factory building, wherein a CFD computer program is used for estimating and adjusting a flow field, a temperature field and a concentration field in the factory building so as to adjust the installation horizontal position and height of at least one air outlet pipeline and the height of at least one windowAnd the wind speed, the temperature and the concentration in the factory building can reach the required values.

When the method is implemented, the plurality of side walls comprise a first side wall, a third side wall, a second side wall and a fourth side wall which are sequentially and continuously arranged, and the first side wall is parallel to the second side wall.

When the exhaust device is implemented, the first side wall and the second side wall are respectively provided with at least one window for exhausting air outwards.

During implementation, one end of the at least one air outlet pipeline is connected with the first side wall, and the other end of the at least one air outlet pipeline is connected with the second side wall, so that the at least one air outlet pipeline is perpendicular to the first side wall and the second side wall respectively.

In practice, the present application further provides at least one partition plate, wherein the at least one partition plate and the at least one pipe are located at the same height and horizontal position.

In practice, at least one of the partitions is a flat plate with a high thermal insulation coefficient for blocking radiant heat emitted downward from the roof.

For further understanding of the present application, the following preferred embodiments are provided to explain the detailed composition and the efficacy of the present application in conjunction with the drawings and figures.

Drawings

Fig. 1 is a schematic perspective view of an air outlet duct installed in a factory building according to a preferred embodiment of the present invention.

Fig. 2 is a side view of fig. 1.

FIG. 3 is a flow chart of the overall parameter design of the plant according to the present application.

Fig. 4 is a schematic diagram of the height of the air outlet duct and the geometric and configuration design parameters of the air outlet in the factory building in step a.

Fig. 5 to 7 are flow charts of geometric design of the height of the air outlet duct and the air outlet of the factory building in step a of the present application.

FIG. 8 is a plot of the 50% non-uniformity definition at step A of the present application.

FIGS. 9 and 10 are partial databases of step A of the present application.

FIG. 11 is a schematic view of the blowing duct with jet direction control according to step B of the present application.

Fig. 12 is a flow chart of the design of the air outlet duct of the method (a) in step B of the present application.

Fig. 13 is a schematic side view of the air outlet duct divided into several sections from upstream to downstream in step B of the present application.

Fig. 14 is an original design diagram of an air outlet duct in step B of the present application.

Fig. 15 is a field diagram of the velocity inside the air outlet duct and the velocity outside the air outlet in step B of the present application.

Fig. 16 is a static pressure distribution diagram of the inside of the air outlet duct after adjustment in step B of the present application.

FIG. 17 shows the maximum wind speed u at each outlet before and after the adjustment in step B of the present application _jm,i And (5) a statistical table.

FIG. 18 shows the flow Q of each outlet before and after the adjustment in step B of the present application _j,i And (5) statistics table.

Fig. 19 shows the percentage of improvement in the total unevenness t of the maximum wind speed of the outlet before and after the adjustment in step B of the present application.

FIG. 20 shows sectional areas A of the air outlet duct sections before and after adjustment in step B of the present application _duct,i And (5) statistics table.

Fig. 21 is a table of design parameters of the original air-out duct before adjustment in step B of the present application.

Fig. 22 is a table of design parameters of the air outlet duct adjusted in step B of the present application.

Fig. 23 is a table of design parameters of the outlet regulator before and after the adjustment in step B of the present application.

FIG. 24 is a flowchart illustrating the design of step C of the present application.

FIG. 25 is a trace gas distribution plot of step C of the present application.

Fig. 26 and 27 are tables of factory design parameters of the case in step C of the present application.

Fig. 28 is a diagram of four different air outlet duct configurations in step C of the present application.

FIG. 29 is a table showing the statistical velocity, temperature, concentration and pressure of the plant operating area analyzed and calculated by CFD computer program in the step C of the present application.

Fig. 30 is a schematic view of another example of the present invention with a partition.

Fig. 31 is a side view of fig. 30.

Fig. 32 and 33 are tables of factory design parameters of another example of the step C of the present application.

Fig. 34 is a velocity vector and streamline distribution diagram of another case of step C of the present application in a cross section of side elevation y =3 m.

Fig. 35 is a temperature field profile of another example of step C of the present application in a cross section of side elevation y =3 m.

Fig. 36 is a concentration field profile of another example of step C of the present application in a cross-section of side elevation y =3 m.

Fig. 37 is a velocity vector and streamline distribution diagram of another case of the present application step C in a cross section of end elevation y =3 m.

Fig. 38 is a temperature field profile of another example of step C of the present application in a cross section of end elevation y =3 m.

Fig. 39 is a concentration field profile of another example of step C of the present application in a cross section of end elevation y =3 m.

Fig. 40 is a velocity vector and streamline distribution diagram of another case of the present application step C in the cross section of the top horizontal plane z =1.8 m.

Fig. 41 is a temperature field profile of another case of step C of the present application in a cross section of z =1.8m in a top view horizontal plane.

Fig. 42 is a concentration field profile of another example of step C of the present application in a cross section at a top view horizontal plane z =1.8 m.

FIG. 43 is a table showing the velocity, temperature, concentration and pressure statistics of the factory building in another example of step C of the present application.

FIG. 44 is a graph comparing the average speed of the two cases without and with diaphragms of step C of the present application with the original plant.

FIG. 45 is a graph comparing the temperature of the two cases without and with the partition in step C of the present application with the original plant.

FIG. 46 is a graph comparing the concentration of the two cases without and with the diaphragm in step C of the present application with the original plant.

FIG. 47 is a graph comparing the pressure of the two cases without and with the diaphragm in step C of the present application with the original plant.

Wherein,

10, air outlet pipeline; 101, an upstream end;

102, a downstream end; 103, a section;

104, an air outlet; 1, factory building;

11, a roof; 12, a first side wall;

13, a third side wall; 14, a second side wall;

15, a fourth side wall; 16, indoor space;

17, a window; 18, a partition plate.

Detailed Description

Referring to fig. 1 and 2, an air outlet duct 10 of the present application is installed in a factory building 1, the factory building 1 mainly includes a roof 11, and a first side wall 12, a third side wall 13, a second side wall 14 and a fourth side wall 15, which are disposed below the roof 11 and continuously and circumferentially arranged in sequence, wherein the first side wall 12 and the second side wall 14 are parallel to each other. The four side walls are enclosed into a rectangle and enclose an indoor space 16 together with the roof 11, and at least one air outlet pipeline 10 is arranged above the indoor space 16. In this embodiment, the four air outlet ducts 10 are spaced and parallel to the third side wall 13 and the fourth side wall 15. Any air outlet pipe 10 has an upstream end 101 and a downstream end 102 according to the air flow direction, any air outlet pipe 10 is divided into a plurality of tapered sections 103 from the upstream end 101 to the downstream end 102, and the lower half of each section 103 of each air outlet pipe 10 has at least one air outlet 104 arranged at intervals for outputting downward blowing air respectively; the first side wall 12 and the second side wall 14 respectively have a plurality of windows 17 horizontally spaced apart for exhausting air.

The method for adjusting the air outlet uniformity of the air outlet pipeline comprises the following steps:

A. a geometric design step for the height of the at least one air-out duct 10 and the air outlet 104, which uses a Data Bank to select and adjust the minimum height h of the duct installation of the at least one air-out duct 10 and the length d of the air outlet 104 _j Width w _j S pitch ratio of _j /d _j 104 of air outlets _j Average wind speed u of air outlet 104 _j 。

B. At least one air outlet duct 10 is designed by first designing a geometric dimension (length L) of the air outlet duct 10 based on the Fluid mechanics basic principle and then calculating the geometric dimension by using a computer program of Computational Fluid Dynamics (CFD) _duct Width W _duct High H _duct) So that the maximum wind speed or flow unevenness of each wind outlet 104 can reach a satisfactory low value.

C. The position configuration design step of at least one air outlet pipeline 10 of the factory building 1 estimates and adjusts a flow field, a temperature field and a concentration field in the factory building 1 by using a CFD computer program so as to adjust the installation horizontal position and the height of the air outlet pipeline 10 and the height of a window 17, so that the air speed, the temperature and the concentration in the factory building 1 reach required values.

Before the step A, the implementation further provides a step of designing the overall parameters of the plant, which is a method for preliminarily estimating the required air volume by the overall parameters based on the thermodynamic principle; the overall parameter design flow chart of the plant 1 is shown in fig. 3. The overall parameters are designed to supply filtered air or cold air from the outside into the plant 1, dilute the high temperature and contaminant concentration in the plant 1, and make the interior of the plant 1 positive. Thus, the temperature and the pollutant concentration in the factory building 1 can be reduced and diluted, and the opportunity that dust outside the factory building 1 enters the factory building 1 from doors, windows, openings and gaps can be reduced

When designing the air intake amount, the overall parameter design method of the factory building 1 needs to consider the influence caused by the 'heating rate' of human bodies and machines. If the surface of the machine is subjected to heat insulation measures, the machine discharges hot air and emitted pollutants are removed through a local ventilation facility, only the heat of a human body is considered, but the air suction volume of the local ventilation facility is added into the calculated air intake volume required below).

The "demanded air volumetric flow rate" estimation comprises:

1. thermodynamic estimation method: if the plant has overheating problem, assuming that the air in the plant maintains the conditions of Homogeneous and Equilibrium during the air supply process, the principle of thermodynamics is usedEstimating the theoretical required air volume flow rate Q _theory . If the total heating rate of human body and machine in the factory building is q, the specific heat of air at normal temperature is c _p Where ρ is the density, Δ T is the temperature at which the air absorbs heat in the plant, m is the theoretical required air mass flow rate, and Q is the theoretical required air volume flow rate _theory . The relationship between the above parameters can be written as:

q＝mc _p ΔT＝(ρQ _theory )c _p ΔT，

thus Q _theory ＝q/(ρc _p ΔT)

If the allowable temperature rise is set, the theoretical required air volume flow rate Q can be calculated according to the above formula _theory . [ note: setting the temperature delta T (such as 0.1 ℃, 0.2 ℃ or 0.3 ℃) allowed to rise by indoor air, and if a 'cooler' is arranged at the upstream of the air supply fan, the temperature in the factory building can reach lower than the temperature of the outside air; if no cooler is installed, the lowest temperature in the factory building can only be as much as the outside air temperature]. Typically "actual required air volume flow rate" Q _total Will convert the theoretical required air volume flow rate Q _theory Multiplying a safety factor k (more than or equal to 1):

Q _total ＝kQ _theory

if the allowable temperature rise is set to be Δ T, the actual required air volume flow rate Q can be calculated according to the above-mentioned formula _total . And if Q _total If the value of (2) is too large and exceeds a reasonable range, the following three ways can be selected for adjustment to reduce Q _total The required amount of (c):

(a) Increasing Δ T to an acceptable value to decrease Q _total ；

(b) A "cooler" is provided upstream of the air supply fan. If the cooler is air conditioner cold air, a small amount of the cooler can be mixed into the supply air by using a bypass mode, and the temperature of the supply air is only reduced a little, so that the delta T has enough margin to adjust Q _total . The same effect can be obtained if the cooler is in other types;

(c) In the hairHeat machines incorporating "local ventilation" to reduce Q _total The value (but must be remembered to add the "local ventilation" air intake to the last calculated "demanded intake" Q _total In (1).

2. An upper limit estimation method for pollutant mass concentration demand: if there is a problem of "excessive pollutant concentration" in the plant, the pollutant mass concentration [ mass fraction (mass fraction) ] is used under the assumption that the air in the plant is maintained in a Homogeneous (Homogeneous) and Equilibrium (Equilibrium) state during the air supply process]Upper limit of demand f _p And mass production rate m of contaminants _p Estimating a theoretical required air mass flow rate m:

f _p ＝m _p /(m+m _p )，

thus m = m _p (1-f _p )/f _p

Dividing the theoretical demand air mass flow rate m by the supply air density rho to obtain the theoretical demand air volume flow rate Q _theory ：

Q _theory ＝m/ρ

Then use the equation Q _total ＝kQ _theory Calculating the actual required air volume flow rate Q _total 。

3. By adjusting the total window opening area A of the factory building _win To change the "wind speed out of the room from the window" V _win And the 'positive pressure' (the value of the pressure in the plant is higher than the pressure of the outside air) delta P in the plant _win Size. Air velocity V flowing out of factory building from window _win ：

V _win ＝Q _total /A _win

"Positive pressure" Δ P in a plant _win : suppose the pressure loss coefficient C of the window ₀ ≈0.5～0.6，

ΔP _win ＝C ₀ (ρV _win ² )/2

4. Repeatedly trying to calculate the total area A of the window opening of the factory building for a plurality of times _win Even adjusting Δ T to make Q _total With positive pressure Δ P indoors _win With wind speed V _win To a suitably feasible value.

Steps A, B and C are techniques for guiding and distributing airflow, and require the details of "hydromechanics", wherein step A is a step of designing the geometry of at least one air outlet duct and air outlet, and the design of the geometry of at least one duct and air outlet aims to:

1. after the airflow is sprayed out from the air outlet pipelines and reaches the head of a person, the airflow needs to be derived at a certain distance so as to reduce the average speed of the airflow when the airflow reaches the head of the person

The 'and' air flow speed is not uniformly distributed in space>

To the target value, so as not to make the person feel uncomfortable: />

(1) The head is blown by high-speed airflow (especially cold air) for a long time, and the average speed of the airflow at the head height is controlled as much as possible

(2) If "the air velocity is spatially non-uniformly distributed

If the air outlet is too large, the jet flow speed is too high below the air outlet; in the area below the offset outlet, the air flow velocity is too low. The spatial distribution of the air velocity at the height of the human head should be as inhomogeneous as possible>

(unevenness tolerance values can also be customized).

2. At least one air outlet pipeline [ average air outlet speed u _j Outlet geometry (length d) _j Width w _j S pitch ratio of _j /d _j )]Will affect' multipleJet derivation distance ". Therefore, it is necessary to establish a Data Bank (Data Bank) using CFD computational analysis to design the average velocity ratio of the air flow to be achieved at a selected head height

And an acceptable spatial distribution unevenness>

The derivation distance (i.e., the minimum distance y from the outlet to the top of the head). The height h of at least one air outlet pipeline is equal to or greater than the height h of a person _p Minimum distance y from the air charging and discharging opening to the top of the human head, namely: h is more than or equal to h _p +y*。

3. According to the basic principle [ step A]Obtaining the number N of air outlet pipelines _duct Minimum height h for mounting air outlet pipeline and long air outlet d _j Width w _j S pitch ratio of _j /d _j Average speed u of air outlet _j Then, go to [ step B ]]Design of outlet pipe geometry (L) _duct ,W _duct ,H _duct ) So as to make the wind speed uniformity of the air outlet meet the requirement.

As shown in fig. 4, it is a schematic diagram of the height of at least one air outlet duct of the factory building, and the geometric and configuration design parameters of the air outlet.

Fig. 5-7 are flow charts of geometric design of the height of the air outlet duct and the air outlet of the factory building.

Fig. 8 is a 50% non-uniformity definition.

Fig. 9 and 10 show part of the database (Data Bank).

The geometric design example of at least one air outlet pipeline height and air outlet of the factory building: in the design example of step a, the Q required for obtaining (length L × width W × height H) = (15m, 12m, 15m) plastic bag plant to reach Δ T =0.2 ℃. (product of step a and product of step b) _total =1536CMM. Please use dilution pressurization method [ step A ]]The design method comprises the following steps: minimum height h for mounting air outlet pipeline and length d of air outlet _j Width w _j S pitch ratio of _j /d _j And the number N of air outlets _j Total area A of air outlet _j Average wind speed u of air outlet _j To average speed of air flow at head height

Air velocity spatial distribution unevenness->

The calculation procedure was as follows:

1. according to [ step A ]]Estimated required air quantity Q _total Selecting a proper number N of air outlet pipelines _duct Calculating the flow Q of a single air outlet pipeline _duct ＝Q _total /N _duct ：

From [ step A ]]To obtain Q _total =1536CMM, assuming "number of outlet ducts" N _duct =4, obtained

Q _duct ＝1536/4＝384CMM。

2. Selecting the height h of the head _p ＝1.8m：

Selecting the minimum height h =7m of the air outlet pipeline with preset erection, and then y = h-h _p ＝7-1.8＝5.2m。

3. Selecting "air outlet length" d _j =0.3m, calculating y x/d _j ：

y*/d _j ＝5.2/0.3＝17.33。

4. Defining a map by 50% non-uniformity, finding s _j /d _j Available range of (c):

to obtain s _j /d _j ≤5.84。

5. Selecting an s _j /d _j Value according to d _j 、y*/d _j 、h/d _j The number of (2) is determined in the database (Data Bank) A

Selecting "air outlet spacing ratio" s _j /d _j =5, according to d _j 、y*/d _j 、s _j /d _j In database A, to identify the spatial non-uniformity of the air flow velocity distribution

Is acceptable. />

6. Calculating s _j ：

s _j ＝(s _j /d _j )×d _j ＝5×0.3＝1.5m。

7. Calculating the number N of air outlets of the air outlet pipeline _j ：

Length L of air outlet pipeline _duct And (5) setting the distance between the air outlets close to the two side wall surfaces of the air outlet pipeline and the wall to be 2m (the distance is the same as the length of the plant). Calculating N _j ＝[(15-2×2-0.3)/1.5]+1=8.13. Selection of N _j =9 → acceptable.

8. By selected N _j Recalculate s is calculated _j ：

With N _j =9 calculating s _j ＝[(15-2×2-0.3)/(9-1)]=1.338m, so s _j /d _j ＝1.338/0.3＝4.46。

With d _j 、y*/d _j 、s _j /d _j Confirming the corresponding air flow speed space distribution unevenness on the Data bank again

9. According to s _j /d _j 、d _j 、y*/d _j 、h/d _j Finding the corresponding average gas flow rate ratio in the database (Data Bank) B

Obtain->

10. Set to be obtained at the head

Calculate->

Setting the average speed of the air flow to be obtained at the head

Computing

Recalculating

11. Calculation of A _j ＝d _j ×w _j ＝0.3×0.5＝0.15m ² 。

12. Calculation of A _j,total ＝N _j ×A _j ＝9×0.15＝1.35m ² 。

13. Calculating u _j ＝Q _duct /A _j,total =384/60/1.35=4.74m/s → acceptable.

14. The minimum height h =7m and the length d of the air outlet are obtained by using the obtained air outlet pipeline _j =0.3m, width w _j =0.5m, pitch ratio s _j /d _j =4.46, outlet number N _j =9, average wind speed u of air outlet _j =4.74m/s in [ step B ]]And designing the geometric dimension of the air outlet pipeline.

Step B is a geometric design step of an air outlet pipeline, and the geometric design of the air outlet pipeline aims at: when air is sent into the air outlet pipeline and then is sprayed out from the air outlets arranged at different positions along the length direction of the air outlet pipeline (for example, the application in heating ventilation air conditioners: air supply pipelines of ventilation systems, pipelines for sending cold air or hot air to various positions, and the like), if the flow rate of the air outlet pipeline, the size of the air outlet pipeline, the speed of the air outlet or the uniformity of the flow rate is not properly designed, in most application examples for delivering enough air volume, because the static pressure distribution in the air outlet pipeline is uneven and increases progressively from upstream to downstream, the jet flow ejection speed of the air outlet increases progressively from upstream to downstream, namely, the uniformly distributed blowing air flow is not easy to obtain, and the jet flow direction is not easy to control. Therefore, a need exists for a methodology to achieve acceptable "airflow distribution" and "directional adjustment".

The speed and direction adjusting method of the air outlet pipeline air outlet comprises the following steps: as shown in fig. 11, the direction of the jet flow from the outlet is controlled by a hollow tube or a guide vane. The CFD calculation is used for adjusting the length of the guide vane and the gap between the adjacent guide vanes so that the jet flow direction reaches a target value. The method for regulating speed or flow uniformity of air outlet pipeline is characterized by that the sectional area A of air outlet pipeline _duct Tapering from upstream to downstream. The method leads the sectional area A of the air outlet pipeline _duct The flow rate is gradually reduced from the upstream to the downstream so as to adjust the static pressure distribution in the pipe, thereby adjusting the speed or the flow uniformity of the air outlet.

As shown in fig. 12, it is the sectional area A of the air outlet pipe _duct A flow chart for designing an air outlet pipeline by a tapering method from upstream to downstream. As shown in fig. 13, in the initial design, the outlet duct 10 is divided into several sections 103 from the upstream end 101 to the downstream end 102, assuming that the velocity of each outlet 104 is u _j ＝Q _duct /A _j,total And the speed of each section 103 of the air outlet pipeline 10 is equal to the inlet speed u of the air outlet pipeline _duct Then, according to the law of mass conservation, the initial sectional area A of each segment 103 is determined _duct,i 。

Assuming that the airflow is an ideal fluid and there is no pressure loss when flowing in the air outlet pipeline, bernoulli's principle (anhydrous hydrostatic pressure P) _hs Dynamic pressure P when changing = gamma h _v + static pressure P _s = constant), if the speed of each segment of the air outlet pipeline is u _duct Then dynamic pressure P _v All the sections of the air outlet pipeline are equal, so the static pressure P is _s All sections in the pipe are equal (namely, all sections of the air outlet pipeline are equal in full pressure); consider again bernoulli's law at the air outlet: when each section of static pressure in the pipe or the static pressure P near each air outlet of the air outlet pipeline _s When the velocities are equal, the velocities u of the air outlets _j The same is true. Therefore, the initial design is based on the mass conservation law and Bernoulli's law to make the speed of each segment of the air outlet pipeline be u _duct And each air outlet speed is u _j ＝Q _duct /A _j,total From this, the initial cross-sectional area of the wind pipe sections can be determined.

It is appropriate to arrange an air outlet in an air outlet pipeline with the same cross section. If the air outlet pipeline is too long or the air outlets are too many, a plurality of air outlets can be arranged in one section of air outlet pipeline with the same sectional area; however, when the arrangement is adopted, in the air outlet pipes with the same section and the same cross-sectional area, the air outlet speed of the air outlet at the upstream side is lower than that of the air outlet at the downstream side.

Moreover, since the actual fluid must have viscosity, the pressure loss must be corrected for each segment in the air outlet duct. Calculating the flow field distribution by CFD, and adjusting the sectional area A of each air outlet pipeline according to the calculation result of the flow field _duct,i So that the speed u of each air outlet _j And (4) uniformity. The initial cross-sectional area A is generally used _duct,i The flow field distribution obtained by calculation has a certain degree of uniformity at the air outlets on the upstream and the midstream of the air outlet pipeline, but the jet flow speeds of the air outlets on the downstream are lower than those of the air outlets on the upstream and the midstream. If adjusted, A _duct,i (while shrinking upstream A _duct,i And increasing A downstream _duct,i ) The uniformity of the air outlet of the whole air outlet pipeline can be improved.

If the air outlets are arranged in a section of air outlet pipeline with the same cross-sectional area, the air outlet speed of the air outlet at the upstream side is lower than that of the air outlet at the downstream side in the air outlet pipeline with the same cross-sectional area. To correct this problem, the air outlet duct with the same sectional area can be changed to be gradually reduced downstream. In addition, use a certain Q _duct Value, according to design, completing configuration and geometry of air outlet pipeline and air outlet, obtaining satisfactory speed uniformity of air outlet, if changing Q in a range _duct The velocity non-uniformity of the air outlet is slightly changed. For example: the following case A, in original Q _duct Within 0.4 to 5 times the value, the variation in the unevenness is approximately negligible.

Respective maximum speed u of air outlet pipeline _jm,i Is of non-uniformity η _t Defining:

u _jm,i : respective maximum speed of the air outlets

u _jm,ave : average of maximum speeds of all outlets

Respective flow Q of air outlet pipeline _j,i Is of non-uniformity η _t Defining:

Q _j,i : respective flow rate of air outlet

Q _j,ave : average flow of all outlets

For example: 18m air outlet pipeline (total 9 air outlets, with Q) _duct ＝5.4m ³ S) the non-uniformity η if the flow is changed while maintaining the same design after the design is improved _t,u The change in (c) is not significant, as shown in the following two tables.

Maximum degree of difference (%): the difference between the maximum value and the minimum value of the air outlet speed of all air outlets of the air outlet pipeline is divided by the average value. Wherein, the sectional area A of each section of the air outlet pipeline _duct,i The adjustment principle is as follows:

1. increase A _duct,i Can increase the maximum speed u of the air outlet _jm,i (ii) a Decrease A _duct,i Can reduce the maximum speed u of the air outlet _jm,i 。

2. Comparing the maximum speed u of each outlet _jm,i And the average value u of the maximum speeds of all the air outlets _jm,ave ，

If u _jm,i <u _jm,ave → increase of A _duct,i ；

If u is _jm,i >u _jm,ave → decrease of A _duct,i 。

And adjusted back and forth until an acceptable speed profile is obtained.

Case a: an air outlet pipeline is originally designed as the list in fig. 14, and after CFD analysis of velocity fields inside and outside the original pipeline and the air outlet, the air outlet velocity of each air outlet is very uneven. Please design to increase the uniformity of the air outlet speed of each air outlet.

The adjustment design process is as follows:

1.Lduct =18m, divide into 9 sections, 1 air outlet in each section.

2. After 4 times of adjustment and design, the speed fields inside the air outlet pipeline and outside the air outlet are as shown in fig. 15, and the speed distribution of each air outlet is uniform; the static pressure distribution inside the air outlet pipeline is shown in figure 16, and the static pressure in the area above the air outlet is uniform.

3. FIG. 17 and FIG. 18 are statistical tables of the adjustment process, in which FIG. 17 shows the maximum wind speed u of each outlet _jm,i The statistical table, according to the initial design of mass conservation and Bernoulli's law, has already improved the "serious nonuniform velocity of each air outlet" problem of the "straight pipe" by a wide margin, but the distribution of the air outlet velocity becomes: the speed of the air outlet at the upstream is higher than that of the air outlet at the downstream, and the speeds of the air outlets at the tail of the pipe are too low. And the size of the air outlet pipeline is continuously adjusted back and forth according to the initial design (the size of the upstream air outlet pipeline is reduced, and the size of the middle and downstream air outlet pipelines is increased), so that the defects of the initial design can be effectively corrected, and the comparison eta of the defects is _t,u0 ＝40.0％。

4. FIG. 18 shows the flow Q of each outlet _j,i Statistical table of u _jm,i And Q _j,i The uniformity of (A) may not be compatible, and it is preferable to select u before the design according to the actual requirement _jm,i Or Q _jm,i As a criterion for the uniformity, a design procedure for adjusting the sectional area of each cut-off duct is performed, and comparison η is made _t,Q0 ＝61.4％。

5. FIG. 19 shows the total unevenness η of the maximum wind speed at the outlet _t The percentage of improvement.

6. FIG. 20 is a sectional area A of each segment of the air outlet pipeline _duct,i Statistical tables, wherein A _duct,1 ～A _duct,3 Than initial design A _duct,i (# 0) Small; and A is _duct,4 ～A _duct,9 Than initial design A _duct,i (# 0) is large.

7. Fig. 21 to 23 are tables for arranging design parameters of the air outlet duct. Wherein, fig. 21 is the original design parameters of the air outlet duct, fig. 22 is the adjusted design parameters of the air outlet duct, and fig. 23 is the design parameters of the air outlet adjuster.

Step C is a design step for configuring the position of the air outlet pipeline of the factory building, and the design flow chart is shown in fig. 24. Factory building air-out pipeline position design aim at: after the steps B and C are completed, the required total air quantity Q is obtained _total Total window area A _win Air quantity Q of single air outlet pipeline _duct Number N of air outlet pipelines _duct Outlet duct geometry (L) _duct ,W _duct ,H _duct ) Length of air outlet d _j Width w _j S pitch ratio of _j /d _j And the number N of air outlets _j And the minimum height h for installing the air outlet pipeline. And step C, adjusting the installation horizontal position and height of the air outlet pipeline and the configuration/height of the window. The horizontal position, height and window arrangement/height of the pipeline installation affect the airflow pattern in the factory building, and also affect the distribution of temperature and concentration. If not properly designed, the velocity, temperature, and concentration distribution within the plant may be very uneven. In the step, a flow field, a temperature field and a concentration field in the plant are calculated and adjusted by CFD, so that the wind speed, the temperature and the concentration in the plant can reach required distribution and values.

The design principle of the factory outlet pipeline configuration is as follows:

1. the configuration method of intensively distributing the air outlet pipelines on one side of the factory building can generate large backflow bubbles in the factory building, and compared with the operation method of averagely distributing the air outlet pipelines on the factory building or intensively distributing the air outlet pipelines in a central area, the air flow in an operation area has higher average speed but has higher and more uneven pollutant concentration distribution.

2. The air outlet pipes are evenly distributed in the factory building or are intensively distributed in the central area, so that a plurality of small backflow bubbles are generated in the factory building, and compared with the air outlet pipes which are intensively distributed on one side of the factory building, the air flow in the operation area has a slightly lower average speed but has a lower and more uniform average concentration of pollutants.

3. The configuration method for distributing the air outlet pipelines evenly in the factory building is similar to the configuration method for distributing the air outlet pipelines intensively in one side or the central area of the factory building in the average temperature of the operation area, but the configuration method for distributing the air outlet pipelines evenly in the factory building and intensively in the central area is slightly more uniform than the configuration method for distributing the air outlet pipelines intensively in the operation area at one side of the factory building in the temperature field.

4. Comparing the distribution and the numerical value of the flow field, the temperature field and the concentration field in the operation area, wherein the quality sequence of the air outlet pipeline distribution mode is as follows:

<1> is distributed centrally in the central area.

And <2> the distribution is evenly distributed in the factory building.

And <3> is intensively distributed at one side of the factory building.

5. The average temperature of the working area can be reduced by reducing the air outlet temperature of the air outlet pipeline near the heating source, and the temperature of the heating machine can also be reduced.

6. The relative orientation arrangement of the air outlet pipeline and the window can affect the types of a flow field, a temperature field and a concentration field. The average speed, temperature and concentration of the operation area of the 'window installation wall surface is axially vertical to the air outlet pipeline' and the 'window installation wall surface is axially parallel to the air outlet pipeline' are all close to the theoretical values of the whole parameter design; but the local concentration field and the temperature field distribution of the 'wall surface for installing the window and the axial direction vertical to the air outlet pipeline' are better than that of 'the wall surface for installing the window and the axial direction parallel to the air outlet pipeline'.

7. When the height of the window is adjusted from below to above the wall surface, the flow field, temperature field, and concentration field in the working area are slightly deteriorated (not greatly different).

Factory building air outlet pipeline position configuration design example: a plant for manufacturing plastic bags, (length L × width W × height H) = (15m, 12m, 15m). There are 4 heating machines (total heating value q =5 kW), which should keep low dust state to avoid sticking on the plastic bag. It is desirable that the difference Δ T between the inside and outside temperatures be less than 0.5 ℃ to maintain product quality.

Wherein (Q) _duct 、A _win 、V _win 、ΔP _win )＝(1536CMM、6m ² 4.27m/s, 5.31 Pa); there are 12 windows, each window (0.625 m wide by 0.8m high).

The method is obtained by a design method of steps A and B of a dilution pressurization method:

step A: number of air ducts N _duct =4, flow per air pipe Q _duct =384CMM, minimum height h =7m of air duct installation, length d of air outlet _j =0.3m, width w _j =0.5m, pitch ratio s _j /d _j =4.46, outlet number N _j =9, average wind speed u of air outlet _j ＝4.74m/s。

And B, step B: sectional area A of air outlet pipeline _duct Designing by a taper method from upstream to downstream, so that the maximum speed of each air outlet is not uniform by 3.4%; the air output of each air outlet is not uniform by 11.8 percent.

Tracking gas release mode:

1. tracing gas: as shown in FIG. 25, in calculating the concentration field, 105 grid points (5 rows in the x direction, 7 rows in the y direction, and 3 rows in the z direction) were arranged on average in the working field (z.ltoreq.3 m), and carbon monoxide (CO) was generated as a trace gas at 2.85mg/s per grid point for m _p ＝300mg/s。

2. Supply of air: q _total ＝1536CMM＝25.6m ³ /s，

P＝101325Pa，T＝29℃，ρ＝1.159kg/m ³ ，

rH＝55％

→m＝Q _total ×ρ＝29.67kg/s，

3. Expected average mass concentration f _p Estimating:

formula designed according to [ step A ] overall parameters of factory building

f _p ＝m _p /(m+m _p )

→f _CO ＝10.111ppm

Referring to fig. 1 and 2, the window of this case has no partition on the wall surfaces of the first side wall 12 and the second side wall 14, and the horizontal position arrangement of the air outlet duct is changed, the design parameter table of the plant 1 of this case is shown in fig. 26 and 27, and the configuration modes (a), (b), (c) and (d) of the air outlet duct 10 are shown in fig. 28. Based on the structure of the above embodiment, the present application performs simulation test with the above parameters, and analyzes the calculation results with a computer program of Computer Fluid Dynamics (CFD), and the statistical table of the speed, temperature, concentration, and pressure of the factory work area is shown in fig. 29.

Please refer to fig. 30 and 31, which illustrate another embodiment of the partition 18. Wherein, a plurality of partition boards 18 are arranged in parallel at intervals under the roof 11, the partition boards 18 and the air outlet pipeline 10 are positioned on the same level at the same height, and the partition boards 18 are flat plate type ceilings with high heat insulation coefficient to block the radiation heat downwards emitted by the roof 11. The factory design parameter table is shown in FIG. 32 and FIG. 33, and the air outlet duct configuration methods (a), (b), (c) and (d) are the same as the previous case.

The results of the analysis and calculation with CFD computer program are shown in fig. 34 for the velocity vector and streamline distribution diagram in the cross section of side elevation y =3 m; the temperature field profile is shown in fig. 35; the concentration field profile is shown in fig. 36. In the cross section of the end elevation x =3m, the velocity vector and streamline distribution diagram is shown in fig. 37; the temperature field profile is shown in fig. 38; the concentration field profile is shown in fig. 39. In a section of the top horizontal plane z =1.8m, the velocity vector and streamline distribution diagram is shown in fig. 40; the temperature field profile is shown in FIG. 41; the concentration field profile is shown in fig. 42. The results of the tests show the statistical table of the speed, temperature, concentration and pressure of the factory building operation area in this example is shown in fig. 43. Wherein the arrow represents the velocity vector and the black area line along the tangential direction of the velocity vector represents the streamline; the colored portion represents the temperature, the roof is assigned a temperature of 60 deg.C, the red is the highest temperature (the temperature on the inner side of the roof is assigned 60 deg.C), and the color is brown, yellow, light green, bright green, light blue to dark blue (the temperature of dark blue is the temperature of the atmosphere and is assigned 29 deg.C). In addition, as shown in fig. 44-47, the two cases without the partition 18 and with the partition 18 are compared with the original plant in terms of average speed, temperature, concentration and pressure, respectively, and show that the cases without the partition 18 or with the partition 18 are superior to the original plant in terms of average speed, temperature, concentration and pressure.

In summary, according to the above disclosure, the present application can achieve the expected purpose, and provide a ventilation and heat dissipation method for a factory building, which can achieve a positive pressure effect in the factory building, so that the pressure in the factory building is higher than the atmospheric pressure outside the factory building, thereby effectively blocking dusts from flowing into the factory building, and reducing the temperature in the factory building, even the concentration of pollutants, and has a great industrial application value.

Claims

1. An air outlet pipeline is characterized in that the air outlet pipeline is arranged in a factory building and is provided with an upstream end and a downstream end, the air outlet pipeline is divided into a plurality of gradually-reduced sections from the upstream end to the downstream end, and the sections are respectively provided with at least one air outlet for respectively outputting downward blowing air.

2. The method according to claim 1, wherein the factory building includes a roof and a plurality of side walls disposed below the roof and sequentially and continuously, the roof and the plurality of side walls together frame an indoor space, the at least one air outlet duct is disposed above the indoor space to provide a plurality of downdraft air flows, and the at least one side wall has at least one window for exhausting air; the method for adjusting the air outlet uniformity of the air outlet pipeline comprises the following steps:

A. at least one air outlet pipeline height and air outlet geometric design step, which uses a database to select and adjust the minimum pipeline installation height h and air outlet length d of the at least one air outlet pipeline _j Width w _j S pitch ratio of _j /d _j And the number N of air outlets _j Average wind speed u of air outlet _j ；

B. The geometric design step of the at least one air outlet pipeline firstly makes a preliminary design by the fluid mechanics basic principle, and then designs the geometric dimension of the at least one air outlet pipeline by the calculation of a CFD computer program so as to ensure that the maximum wind speed or the flow unevenness of a plurality of air outlets reaches a satisfactory low value; and

C. the position configuration design step of the at least one air outlet pipeline of the factory building estimates and adjusts a flow field, a temperature field and a concentration field in the factory building by a CFD computer program so as to adjust the installation horizontal position and the height of the at least one air outlet pipeline and the height of the at least one window, so that the air speed, the temperature and the concentration in the factory building reach required values.

3. The method of claim 2, wherein the plurality of side walls includes a first side wall, a third side wall, a second side wall and a fourth side wall sequentially disposed in series, and the first side wall is parallel to the second side wall.

4. The method of claim 3, wherein the first side wall and the second side wall have at least one window respectively for exhausting air outwards.

5. The method of claim 4, wherein one end of the at least one air outlet duct is connected to the first sidewall, and the other end of the at least one air outlet duct is connected to the second sidewall, so that the at least one air outlet duct is perpendicular to the first sidewall and the second sidewall, respectively.

6. The method of claim 2, further comprising providing at least one partition plate, wherein the at least one partition plate and the at least one duct are located at a same height and horizontal position.

7. The method of claim 6, wherein the at least one partition is a flat plate with high thermal insulation coefficient for blocking the downward radiation heat emitted from the roof.