Method for determining on-way air supply quantity and fan parameters on air leakage pipeline under condition that fans are connected in series at intervals

Abstract

The invention relates to the technical field of construction tunnel ventilation systems, in particular to a method for determining the on-way air supply amount and fan parameters under the condition that fans on an air leakage pipeline are connected in series at intervals, and the method comprises the following steps that a first fan, a first air leakage pipeline and a second fan are sequentially connected in series to form a combined air supply device; and calculating a rising pressure and air volume change curve of the combined air supply device and a combined flow resistance and air volume change curve of the second air leakage pipeline and the tunnel, and determining a working point of the combined air supply device through an intersection point of the two curves. And further determining the operation parameters of the first fan and the second fan, the on-way air supply amount of the air leakage pipeline and the tail end air supply amount of the second air leakage pipeline. By accurately calculating the air supply amount and the fan operation parameters, efficient optimization of the construction tunnel ventilation system is achieved, energy consumption is remarkably reduced, the tail end air supply effect is improved, and the ventilation requirement in the complex tunnel construction environment is met.

Description

Technical Field

[0001] The invention relates to the technical field of construction tunnel ventilation systems, and in particular to a method for determining the air supply volume and fan parameters along a leaky duct when fans are connected in series at intervals. Background Art

[0002] In construction tunnels, due to the complex construction environment and long-distance ventilation requirements, duct leakage becomes a key issue affecting the air supply at the end of the forced ventilation duct. Insufficient air supply at the end has an adverse effect on the air quality of the construction environment. By setting fans in series at a certain distance on the leaking duct, the air supply capacity and coverage of the forced ventilation system can be significantly improved. Accurate determination of the air supply at the end of the duct and the fan operating parameters is crucial to evaluating and improving the quality of the construction environment and reducing fan energy consumption.

[0003] In the prior art, a single fan or two fans are often installed in series at the beginning of the air duct to achieve air supply, which is different from the installation position of the first and second fans in this patent. The prior art fails to fully consider the comprehensive performance of multiple fans connected in series at a certain distance and under the influence of pipeline leakage. The calculation method of the air supply volume at the end of the air duct and the fan operating parameters is not suitable for the situation of this patent, resulting in the following defects:

[0004] It is impossible to accurately calculate the air supply volume at the end of the second leaky duct according to the progress of construction, resulting in the inability to assess whether the air supply volume meets the air volume requirements of tunnel construction; it is impossible to accurately assess the operating parameters of the first and second fans according to the progress of construction, resulting in low fan operating efficiency and excessively high operating energy consumption; it is impossible to optimize the fan settings and fan spacing distances according to the progress of construction to meet the terminal air supply volume requirements and reduce the fan operating energy consumption. Summary of the invention

[0005] In view of the many problems existing in the above-mentioned prior art, the present invention provides a method for determining the air supply volume and fan parameters along the way when fans are connected in series at intervals on a leaky duct. The present invention connects a correction fan formed by a first fan and a first leaky duct and a second fan in series to form a combined air supply device, dynamically calculates the pressure rise and air volume change curve of the combined air supply device, and the intersection with the joint flow resistance and air volume change curve of the second leaky duct and the tunnel, determines the working point of the combined air supply device, and further accurately calculates the air supply volume along the leaky duct and the operating parameters of the first fan and the second fan, evaluates whether the air supply volume at the end of the air duct meets the required air volume of the tunnel, and evaluates the operating energy consumption of the fan at the same time; based on this, the fan setting and the spacing between fans are further optimized to reduce the fan operating energy consumption and improve the terminal air supply effect.

[0006] A method for determining the air supply volume and fan parameters along the way when fans are connected in series at intervals on a leaky duct comprises the following steps:

[0007] A combined air supply device is provided for air supply, wherein the combined air supply device is composed of a first fan, a first air leakage duct and a second fan connected in series in sequence, wherein the first fan is combined with the first air leakage duct to form a correction fan;

[0008] Calculate the variation curve of the pressure rise and air volume of the combined air supply device, and calculate the variation curve of the combined flow resistance and air volume of the second air leakage duct and the tunnel;

[0009] The working point of the combined air supply device is determined by the intersection of the change curve of the pressure rise and air volume of the combined air supply device and the change curve of the combined flow resistance air volume of the second air leakage duct and the tunnel;

[0010] According to the working point of the combined air supply device, the operating parameters of the first fan and the second fan, the air supply volume along all the leaky air ducts and the air supply volume at the end of the second leaky air duct are determined.

[0011] Preferably, a leakage point is set at a fixed distance along the length direction of the first leaky air duct and the second leaky air duct to simulate the leakage characteristics of the air supply duct, and the fixed distance of the leakage point is dynamically adjusted according to the construction environment.

[0012] Preferably, the number, distribution and leakage amount of the leakage points of the first leaky air duct and the second leaky air duct are determined by analyzing the air circulation requirements of the construction tunnel and the fluid mechanics parameters of the leaky air duct and the tunnel.

[0013] Preferably, the pressure rise and air volume variation curve of the combined air supply device is calculated by superimposing the pressure rise and air volume variation curve of the correction fan and the pressure rise and air volume variation curve of the second fan.

[0014] Preferably, the variation curve of the boost pressure and air volume of the modified fan is determined by the following steps:

[0015] Calculating the relationship between the flow resistance and the air volume of the first air leakage duct;

[0016] Determining the lift pressure of the correction fan according to the lift pressure of the first fan minus the flow resistance of the first leaky duct;

[0017] Determining the air volume of the correction fan according to the air volume of the first fan minus the total air leakage volume of the first air leakage duct;

[0018] The air volume of the first fan is changed, and the calculation is repeated to obtain a variation curve of the boost pressure and air volume of the modified fan.

[0019] Preferably, the variation curve of the combined flow resistance and air volume of the second air-leaking duct and the tunnel is determined by adding the flow resistance of the second air-leaking duct and the flow resistance of the tunnel.

[0020] Preferably, the flow resistance of the first leaky air duct and the second leaky air duct is obtained by comprehensively calculating the air leakage at each leakage point along the way and the air volume, air density, duct diameter, duct roughness and local resistance coefficient changes along the duct.

[0021] Preferably, the operating parameters of the first fan and the second fan include air volume, boost pressure, power and efficiency, and the operating parameters are determined by the performance curves of the first fan and the second fan and the air volume of the first fan and the second fan; the air volume of the first fan and the second fan is determined by the correspondence with the working point of the combined air supply device.

[0022] Preferably, the distance between the first fan and the second fan and the settings of the first fan and the second fan are dynamically adjusted according to the progress of construction, and the dynamic adjustment is optimized based on the operating parameters of the first fan and the second fan and the air supply volume at the end of the second leaky duct.

[0023] Preferably, the air volume along all leaky ducts is determined by subtracting the air volume of the first fan from the air volume of the leaky points along the way. The air volume at the end of the second leaky duct is determined by subtracting the sum of the air volume of each leaky point along all leaky ducts from the air volume of the first fan.

[0024] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0025] The present invention realizes accurate determination of the working point of the combined air supply device, the working point of the first fan, and the working point of the second fan by dynamically calculating the change curve of the boost pressure and the air volume of the combined air supply device, and the change curve of the combined flow resistance and the air volume of the second air leakage duct and the tunnel, thereby solving the problem that the prior art cannot accurately predict.

[0026] The present invention dynamically adjusts the settings of the first fan and the second fan and the spacing between the fans according to the progress of the construction, thereby reducing the operating cost of the fans.

[0027] The present invention achieves an evaluation of the effectiveness of long-distance air supply by accurately calculating the air supply volume at the end of the second air leakage duct and comparing it with the air volume required for the construction tunnel;

[0028] The present invention simulates the air circulation characteristics in a complex construction environment and improves the adaptability and stability of the air supply system;

[0029] The calculation method adopted in the present invention can be extended to the case where three or more fans are connected in series on a leaky duct at intervals, and the leaky duct can be divided into a first leaky duct, a second leaky duct, a third leaky duct, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of the present invention;

[0031] Figure 2 This is a schematic diagram of the calculation of ventilation of fans in series with intervals in the present invention;

[0032] Figure 3 A diagram for determining the pressure rise and air volume change curve of the combined air supply device in the present invention;

[0033] Figure 4 This is a diagram for determining the working point of the combined air supply device, the working point of the first fan and the working point of the second fan in the present invention.

[0034] Figure 5 A diagram showing changes in air volume along the leaky air duct in the present invention. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0036] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0037] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0038] like Figure 1 As shown, a method for determining the air supply volume and fan parameters along the leaky duct under the condition that fans are connected in series at intervals, comprises the following steps:

[0039] (1) Division of calculation segments

[0040] In the construction tunnel pressure ventilation system, the first fan and the second fan are connected in series at a certain distance to supply air; draw a calculation diagram ( Figure 2 ) to determine the location of the air leakage point of the pipeline; along the air supply direction, according to the location of the air leakage point, all the air leakage pipelines are numbered as (1), ..., (I), ..., (N) calculation sections in sequence, where the first fan is located outside the (1) section, and the second fan is located between the (J) and (J+1) sections; along the direction from the working face to the tunnel entrance, the tunnels are numbered as (0), (1), ..., (N) calculation sections in sequence.

[0041] (2) Calculation of air volume in the calculation section

[0042] The air volume leaked through each leakage point along the first and second air leakage ducts is expressed as q l The air volume along the first leaky duct and the second leaky duct is expressed as q d , the wind volume along the tunnel is expressed as q t ; They are respectively expressed as follows:

[0043] q l =(q l,1 ,…,q l,I ,…q l,N-1 )

[0044] q d =(q d,1 ,…,q d,I ,…q d,N )

[0045] q t =(q t,0 ,…,q t,N-I+1 ,…q t,N )

[0046] In the formula, q l,I is the air leakage volume of any section of the leaky duct (expressed as section (I)), q d,I is the air supply volume of any section of the leaky duct (represented by section (I)), q t,N-I+1 It is the air volume of the tunnel section (expressed as (N-I+1) section) corresponding to any section of the above-mentioned air leakage duct.

[0047] Assume that the air duct leakage coefficient is k d , determine the air supply volume and air leakage volume of any section of the leaking duct (represented by section (I)):

[0048] q d,I =q f,1 (1-k d ) I

[0049] q l,I =q f,1 k d (1-k d ) I

[0050] where q f,1 It is the air volume of the first fan installed at the entrance of the ventilation duct.

[0051] Assuming that the leaked air is fully mixed with the air in the tunnel and flows to the tunnel exit, the air volume in the (N-I+1) section of the tunnel is determined according to the law of conservation of mass:

[0052] q t,N-I+1 =q f,1 (1-k d ) I

[0053] According to the air supply volume of the leaky duct (N) section, determine the air supply volume q at the end of the second leaky duct d,w :

[0054] q d,w =q d,N =q f,1 (1-k d ) N

[0055] (3) Determination of the flow resistance-air volume curve of the first air leakage duct

[0056] Given the air volume of the first fan q f,1 , considering the flow resistance along the way and the local resistance, the flow resistance of the first leaky duct is calculated as follows:

[0057]

[0058] Among them, ⊿P d1 S is the flow resistance of the first air leakage duct. d1 is the flow impedance of the first leaky duct. d is the equivalent diameter of the first leaky duct. ρ is the air density. d is the length of each calculated section of the leaky duct. in is the local resistance coefficient at the inlet of the first air leakage duct. d is the local resistance coefficient of the local resistance places such as the diameter change and the bend in the first air leakage duct (located in the (O1) section). d is the resistance coefficient along the leaky duct.

[0059] Change the air volume q of the first fan f,1 Repeat the above calculation to get the flow resistance-air volume curve of the first air leakage duct, see Figure 3 .

[0060] (4) Determination of the combined flow resistance-air volume change curve of the second air leakage duct and tunnel

[0061] The combined flow resistance of the second leaky duct and tunnel is:

[0062]

[0063] Among them, ⊿P d2 is the flow resistance of the second air leakage duct. ⊿P t is the flow resistance of the tunnel. d2+t It is the combined flow resistance of the second air leakage duct and tunnel. d and D t are the equivalent diameters of the second air leakage duct and the tunnel respectively. ρ is the air density. d is the length of each calculation section of the air leakage duct and tunnel (except section (0)). l0 is the length of section (0) of the tunnel, i.e., the distance between the working face and the outlet of the second air leakage duct. out is the local resistance coefficient of the second air leakage duct outlet or tunnel outlet. d ζ is the local resistance coefficient of the local resistance places such as the diameter change and the bend in the second air leakage duct (located in the (O2) section). t is the local resistance coefficient at the local resistance point in the tunnel (located in the (S) section). d and λ t is the resistance coefficient along the second air leakage duct and tunnel. f,2 is the air volume of the second fan, calculated as follows:

[0064] q f,2 =q f,1 (1-k d ) J

[0065] Change the air volume q of the first fan f,1 , repeating the above calculation, we can get the combined flow resistance-air volume curve of the second air leakage duct and tunnel, see Figure 3 .

[0066] (5) Determination of the pressure-air volume change curve of the combined air supply device

[0067] like Figure 2 As shown, the combined air supply device is to install the first fan outside the inlet of the first air leakage duct, and the second fan is separated by a certain air duct section (length L d1 =Jl d ) is connected in series with the first fan, so the first fan and the first leaky air duct can be connected in series as a whole to form a correction fan; the correction fan and the second fan are connected in series as a whole to form a combined air supply device.

[0068] In a specific embodiment, according to the technical parameters of the fan manufacturer, the following relationship is regressed to obtain the pressure-air volume change curves of the first fan and the second fan, see Figure 3 .

[0069] ΔP f,1 =f1(q f,1 )

[0070] ΔP f,2 =f2(q f,2 )

[0071] like Figure 3 As shown, assuming that the working point of the first fan is point A and the air volume is q f,1 , then the corresponding first fan boost pressure can be determined to be ΔP A =ΔP f,1 =f1(q f,1 ).

[0072] According to the flow resistance-air volume curve of the first air leakage duct, and the air volume of the first fan is q f,1 , the flow resistance of the first leaky duct can be determined as

[0073] According to the following formula, the total air leakage of the first air leakage duct q can be obtained: l,d1 :

[0074]

[0075] Corrected fan outlet ( Figure 3 The air volume (q) at point C C ) and pressure rise (ΔP C ) can be calculated as:

[0076] q C =q f,1 -q l,d1

[0077] ΔP C =ΔP f,1 -ΔP d1

[0078] There is no air leakage between the correction fan and the second fan, and the two are connected in series to form a combined air supply device. According to the air volume of the correction fan, the working point of the second fan is determined as Figure 3 Point D, the air volume of the second fan (q f,2 )for:

[0079] q f,2 =q D =q C =q f,1 -q l,d1

[0080] According to the air volume of the second fan and the pressure-air volume curve, the pressure rise of the second fan (ΔP f,2 ):

[0081] ΔP f,2 =ΔP D =f2(q f,2 )

[0082] Combined air supply device outlet ( Figure 3 The air volume at point E) is equal to the air volume of the correction fan and the second fan, so:

[0083] q E =q C =q D =q f,1 -q l,d1

[0084] The boost pressure of the combined air supply device is:

[0085] ΔP E =ΔP C +ΔP D =ΔP f,1 -ΔP d1 +ΔP f,2

[0086] Change the air volume (q f,1 ), repeat the above calculation steps to get the corresponding q C and ΔP C The corresponding q E and ΔP E Value. ΔP C -q C The change curve of is the modified fan pressure-air volume change curve, see Figure 3 . ΔP E -q E The change curve of is the pressure rise-air volume change curve of the combined air supply device, see Figure 3 .

[0087] (6) Determination of the working point of the combined air supply device

[0088] The pressure-air volume variation curves of the first fan, the second fan, and the combined air supply device, as well as the combined flow resistance-air volume variation curves of the second air leakage duct and the tunnel are plotted on Figure 4 The intersection of the two curves ( Figure 4 Point F) is the working point of the combined air supply device.

[0089] (7) Determination of the operating parameters of the second fan

[0090] Because the air volume of the second fan is equal to that of the combined air supply device, Figure 4 The intersection of the vertical line through point F and the pressure-air volume curve of the second fan is the working point of the second fan (F2). The intersection of the vertical line through point F2 and the horizontal axis determines the air volume of the second fan to be q f,2 According to the performance curve of the second fan and the air volume of the second fan, the boost pressure, power and efficiency of the second fan can be obtained.

[0091] (8) Determination of the operating parameters of the first fan

[0092] According to the air volume of the second fan (q f,2 ) and the total air leakage of the first air leakage duct (q l,d1 ), we can get the air volume of the first fan (q f,1 ):

[0093] q f,1 =q f,2 +q l,d1

[0094] like Figure 4 As shown, according to the air volume (q f,1 ), the working point of the first fan can be determined ( Figure 4 Click F1).

[0095] The boost pressure, power and efficiency of the first fan can be obtained according to the performance curve of the first fan and the air volume of the first fan.

[0096] (9) Determination of air volume along the leaky duct

[0097] According to the air volume of the first fan (q f,1 ), and the duct leakage coefficient k d , calculate the air supply volume of any calculated section of the leaky duct in sequence:

[0098] q d,I =q f,1 (1-k d ) I

[0099] The air volume along the leaking duct is further obtained:

[0100] q d =(q d,1 ,…,q d,I ,…q d,N )

[0101] The change of air volume along the leaky duct is shown in Figure 5 .

[0102] (10) Determination of air supply volume at the end of the second leaky duct

[0103] According to the air supply volume of the leaky duct (N) section, determine the air supply volume q at the end of the second leaky duct d,w

[0104] q d,w =q d,N =q f,1 (1-k d ) N

[0105] (11) Evaluation of air supply effectiveness during construction

[0106] During the construction period, as the construction progresses, the length of the air supply duct increases continuously. According to different air supply duct lengths, the above calculations (1)-(10) are repeated to obtain the operating parameters of the first fan and the second fan, and the air supply volume at the end of the second leaky air duct.

[0107] Based on the fan operating parameters, the fan operating energy consumption level can be judged.

[0108] By comparing the air volume at the end of the second leaky duct with the required air volume of the tunnel, it can be determined whether the forced ventilation can meet the ventilation needs of the tunnel construction:

[0109] When the air volume at the end of the second air leakage duct is greater than the required air volume of the tunnel, forced ventilation can meet the ventilation needs of the tunnel. When the air volume at the end of the second air leakage duct is less than the required air volume of the tunnel, forced ventilation does not meet the ventilation needs of the tunnel. When forced ventilation does not meet the ventilation needs of the tunnel, or the energy consumption of the fan is too high, the following adjustments can be made: Change the configuration of the first fan and the second fan, such as the fan speed, fan blade installation angle, fan capacity, etc. Change the spacing between the first fan and the second fan.

[0110] Repeat the above calculations (1)-(10) to determine the operating parameters of the first fan and the second fan and the air supply volume at the end of the second leaky duct. Continue to evaluate until the ventilation demand is met while controlling the fan energy consumption.

[0111] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0112] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for determining the air volume and fan parameters along the way when fans are connected in series at intervals on a leaky duct, characterized in that: The following steps are involved: A combined air supply device is provided for air supply, wherein the combined air supply device is composed of a first fan, a first air leakage duct and a second fan connected in series in sequence, wherein the first fan is combined with the first air leakage duct to form a correction fan; Calculate the variation curve of the pressure rise and air volume of the combined air supply device, and calculate the variation curve of the combined flow resistance and air volume of the second air leakage duct and the tunnel; The working point of the combined air supply device is determined by the intersection of the change curve of the pressure rise and air volume of the combined air supply device and the change curve of the combined flow resistance air volume of the second air leakage duct and the tunnel; According to the working point of the combined air supply device, the operating parameters of the first fan and the second fan, the air supply volume along all the leaky air ducts and the air supply volume at the end of the second leaky air duct are determined.

2. The method according to claim 1, characterized in that: The first air-leaking duct and the second air-leaking duct are provided with a leakage point at fixed intervals along the length direction to simulate the air leakage characteristics of the air supply duct, and the fixed distances of the leakage points are dynamically adjusted according to the construction environment.

3. The method according to claim 2, characterized in that The number, distribution and leakage amount of the leakage points of the first leaky air duct and the second leaky air duct are determined by analyzing the air circulation requirements of the construction tunnel and the fluid mechanics parameters of the leaky air duct and the tunnel.

4. The method according to claim 1, characterized in that: The pressure rise and air volume variation curve of the combined air supply device is obtained by superimposing the pressure rise and air volume variation curve of the correction fan and the pressure rise and air volume variation curve of the second fan.

5. The method according to claim 4, characterized in that The variation curve of the boost pressure and air volume of the modified fan is determined by the following steps: Calculating the relationship between the flow resistance and the air volume of the first air leakage duct; Determining the lift pressure of the correction fan according to the lift pressure of the first fan minus the flow resistance of the first leaky duct; Determining the air volume of the correction fan according to the air volume of the first fan minus the total air leakage volume of the first air leakage duct; The air volume of the first fan is changed, and the calculation is repeated to obtain a variation curve of the boost pressure and air volume of the modified fan.

6. The method according to claim 1, characterized in that The variation curve of the combined flow resistance and air volume of the second air-leaking duct and the tunnel is determined by adding the flow resistance of the second air-leaking duct to the flow resistance of the tunnel.

7. The method according to claim 1, characterized in that The flow resistance of the first leaky air duct and the second leaky air duct is obtained by comprehensively calculating the air leakage at each leakage point along the way and the air volume, air density, duct diameter, duct roughness and local resistance coefficient changes along the duct.

8. The method according to claim 1, characterized in that: The operating parameters of the first fan and the second fan include air volume, boost pressure, power and efficiency, and the operating parameters are determined by the performance curves of the first fan and the second fan and the air volume of the first fan and the second fan; the air volume of the first fan and the second fan is determined by the correspondence with the working point of the combined air supply device.

9. The method according to claim 8, characterized in that The distance between the first fan and the second fan and the settings of the first fan and the second fan are dynamically adjusted according to the progress of the construction, and the dynamic adjustment is optimized based on the operating parameters of the first fan and the second fan and the air supply volume at the end of the second leaky duct.

10. The method according to claim 1, characterized in that The air volume along the way of all leaky ducts is determined by deducting the air volume of the first fan from the air volume of the leaky points along the way. The air volume at the end of the second leaky duct is determined by deducting the sum of the air volume of each leaky point along the way of all leaky ducts from the air volume of the first fan.

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