A top air outlet structure of a circumferential air outlet box-type substation and a design method thereof

Abstract

The application relates to a top air outlet structure and design method of a circumferential air outlet box-type substation, which comprises a box cover, an air outlet seat is arranged on the box cover, a fan is arranged in the air outlet seat, a plurality of air outlets are arranged on the circumferential outer side of the air outlet seat, an inclined downward air guide protection cover is arranged outside the air outlets, and a filtering assembly is arranged at the end of the air outlet; a cover plate capable of being turned open is arranged on the upper side of the air outlet seat. The structure utilizes the air guide protection cover as an air exhaust channel, and the air guide protection cover is arranged along the circumferential direction of the air outlet seat to realize circumferential air outlet, which can increase the air outlet rate of the fan and ensure the air outlet area of the fan. The method fully considers factors such as allowable temperature rise, along-the-way resistance, local resistance, filtering resistance, air guide protection cover sectional area and the like, and can ensure that the finally determined number of fans meets the heat dissipation requirement.

Description

Technical Field

[0001] This invention relates to the field of prefabricated substations, specifically to a top-mounted air outlet structure and design method for a prefabricated substation with circumferential air outlet. Background Technology

[0002] The overall heat dissipation performance of prefabricated substations is a crucial factor affecting their stable operation. Currently, there are two main heat dissipation methods for prefabricated substations:

[0003] 1. Side-exhaust method. This method is prone to backflow between the fan and the louvers, causing the exhaust air from the prefabricated substation to be drawn back into the substation before it can exchange heat with the external environment. In other words, the heat exhausted by the fan will re-enter the substation through the louvers, reducing heat dissipation efficiency. Furthermore, due to the special structure of the transformer, some coils are always far from the fan and cannot dissipate heat in time, further reducing heat dissipation efficiency.

[0004] Second: Top-mounted air outlet. This method installs multiple fans on the outside of the casing, effectively avoiding the aforementioned drawbacks. However, due to the large number of fans, it occupies a lot of space and also increases equipment maintenance costs, installation costs, and failure rates. One reason for the large number of fans is that existing structures typically only allow unidirectional airflow from the top of the fans, so increasing the number of fans is necessary to ensure efficient heat dissipation. Summary of the Invention

[0005] The purpose of this invention is to provide a top-mounted air outlet structure and design method for a box-type substation with circumferential air outlet. The structure utilizes a guide shield as the exhaust channel, and the guide shield is arranged circumferentially along the air outlet base to achieve circumferential air outlet. This increases the air outlet velocity of the fan while ensuring the fan's outlet area. The method of this invention fully considers factors such as allowable temperature rise, friction loss, local resistance, filtration resistance, and the cross-sectional area of ​​the guide shield, ensuring that the final determined number of fans meets the heat dissipation requirements.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A top air outlet structure for a box-type substation with circumferential air outlet includes a box cover, an air outlet seat on the box cover, a fan inside the air outlet seat, multiple air outlets on the outer circumference of the air outlet seat, and a downwardly inclined air guide protective cover outside the air outlets. A filter assembly is provided at the end of the air outlet. A cover plate that can be flipped open is provided on the upper side of the air outlet seat.

[0008] The air guide shield is inclined downwards at an angle of 20° to 45° to the horizontal direction.

[0009] One side of the cover plate is rotatably connected to one side of the air outlet seat. Both ends of the air outlet seat are provided with a retractable cover plate driving device, and the cover plate is driven to flip by the cover plate driving device.

[0010] One end of the cover plate driving device is rotatably mounted on the hinge seat on the inner wall of the corresponding side of the air outlet seat, and the other end is rotatably connected to the cover plate through the hinge shaft.

[0011] The upper opening edge of the air outlet seat is provided with a sealing element, and the cover plate is in close contact with the sealing element when closed.

[0012] The box cover is equipped with an air guide duct, which is located below the corresponding fan. The air guide duct has a tapered structure that is narrow at the top and wide at the bottom.

[0013] The air outlet seat is divided into multiple fan chambers by fan partitions, and the fan is located in the corresponding fan chamber.

[0014] Each corner of the fan chamber is equipped with a windproof baffle.

[0015] A design method for the top air outlet structure of a box-type substation with circumferential air outlet, comprising the following steps:

[0016] Step 1: Determine the total heat loss P of the transformer inside the box-type substation according to the following formula (1). loss :

[0017] P loss =P0+P K (1);

[0018] In equation (1) above, P0 is the no-load loss of the transformer, P K For transformer load losses;

[0019] Step 2: Determine the allowable temperature rise ΔT according to the following formula (2):

[0020] ΔT = T1 - T2 (2);

[0021] In the above formula (2), T1 is the allowable operating temperature of the transformer inside the box-type substation, and T2 is the highest ambient temperature around the box-type substation.

[0022] Step 3: Determine the theoretical ventilation volume Q according to the following formula (3). V :

[0023] Q V = P loss / (ρ×c p ×ΔT) (3;

[0024] In equation (3) above, ρ is the air density, and c p The specific heat capacity of air at constant pressure;

[0025] Additionally, this step requires Q to be... V Unit conversion to m³ / h, i.e.:

[0026] Q h =3600×Q v ;

[0027] Step 4: Determine the safety factor K S And obtain the design ventilation volume Q design ,in:

[0028] Q design =K S ×Q h (4);

[0029] In equation (4) above, K S The value range is 1.2 to 1.5;

[0030] Step 5: Determine the wind speed v in the ventilation duct of the box-type substation according to the following formula (5):

[0031] v=Q design ’ / A OUT (5);

[0032] In equation (5) above, A OUT Q is the total cross-sectional area of ​​the wind deflector shield. design ’ =Q design / 3600;

[0033] Step 6: Determine the total resistance loss ΔP of the ventilation duct of the box-type substation according to the following formula (6). total :

[0034] ΔP total =ΔP f +ΔP j (6);

[0035] In equation (6) above, ΔP f The friction loss is determined according to the following formula (7):

[0036] ΔP f =λ×(L / D h )×(ρ×v 2 / 2) (7)

[0037] In equation (7) above, λ is the friction coefficient, L is the duct length, and D is the friction factor. h The hydraulic diameter of the air duct;

[0038] In equation (6) above, ΔP j The local resistance loss is determined according to the following formula (8):

[0039] ΔP j =ξ×(ρ×v 2 / 2) (8;

[0040] In equation (8) above, ξ is the local drag coefficient;

[0041] Step 7: Consider the additional resistance ΔP of the filter assembly (206) filter The final total drag loss ΔP is determined according to the following formula (9). total ’ :

[0042] ΔP total ’ =ΔP total +ΔP filter (9);

[0043] Step 8: Determine the total pressure P of the fan according to the following formula (10). fan :

[0044] P fan ≥ΔP total ’ (10);

[0045] Step 9: Determine the fan verification shaft power N according to the following formula (11):

[0046] N = (Q) design ’ ×P fan ) / (η fan ×1000) (11)

[0047] In equation (11) above, η fan For fan efficiency;

[0048] Step 10: Determine the number of fans n and verify the total power, where:

[0049] n= Q design / Q single (12);

[0050] In equation (12) above, Q single The rated air volume for a single fan;

[0051] Then check the total power according to the following formula (13):

[0052] n×N single ≥N (13);

[0053] In the above equation (13), N single This refers to the shaft power of a single fan.

[0054] In step six, the local resistance coefficient ξ includes the local resistance coefficient ξ1 formed by the 90° equivalent duct bend and the local resistance coefficient ξ2 formed by the equivalent conical air guide tube. Each air outlet on the same side is regarded as a 90° equivalent duct bend, and the cross-sectional area of ​​the equivalent duct bend is equal to the sum of the cross-sectional areas of each air outlet on the corresponding side. The lower end of the air outlet seat and the box-type substation are regarded as an equivalent conical air guide tube.

[0055] The advantages and positive effects of this invention are as follows:

[0056] 1. This invention utilizes a flow guide shield as an exhaust channel, and the flow guide shield is arranged around the circumference of the air outlet seat to achieve circumferential air outlet. This can increase the air outlet speed of the fan and ensure the air outlet area of ​​the fan, thereby reducing the number of fans. In addition, the downward inclined flow guide shield can also be consistent with the exhaust direction of the fan, thereby further reducing wind resistance.

[0057] 2. The present invention has a cover plate that can be rotated and opened at the upper end of the air outlet seat. When the cover plate is closed, the upper end of the air outlet seat is sealed. This ensures that the gas inside the box-type substation can only be discharged from the various air outlets arranged around the circumference of the air outlet seat under the action of the fan. When the cover plate is opened, equipment maintenance and other operations can be performed.

[0058] 3. The design method of the present invention is based on the heat generation of transformer losses and combines allowable temperature rise, air duct resistance, etc. to quantitatively design air volume. The method of the present invention not only calculates the theoretical air volume, but also introduces factors such as friction loss, local resistance loss (elbow, diameter change of conical air guide tube, etc.), additional resistance loss of filter components, and cross-sectional area of ​​air guide shield, so that the calculated total pressure of the fan is closer to the actual operating conditions, and can ensure that the final determined number of fans meets the heat dissipation requirements. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of the present invention.

[0060] Figure 2 for Figure 1 A schematic diagram of the structure of the center air outlet and the fan.

[0061] Figure 3 for Figure 1 Side view of the structure of the present invention.

[0062] Figure 4 This is a schematic diagram of the working state of the structure of the present invention.

[0063] Figure 5 for Figure 4 A schematic diagram of the air outlet structure inside the central airflow guide shield.

[0064] Figure 6This is a flowchart illustrating the method of the present invention.

[0065] In this configuration, 1 is the box cover, 101 is the air duct, 2 is the air outlet, 201 is the cover plate, 2011 is the handle, 202 is the cover plate drive device, 203 is the anti-wind baffle, 204 is the fan partition, 205 is the air outlet, 206 is the filter assembly, 3 is the air guide protective cover, and 4 is the fan. Detailed Implementation

[0066] The invention will now be described in further detail with reference to the accompanying drawings.

[0067] like Figures 1-5 As shown, the structure of the present invention includes a box cover 1, and the box cover 1 is provided with an air outlet seat 2. The air outlet seat 2 is provided with a fan 4 inside. The air outlet seat 2 is provided with a plurality of air outlets 205 on the outer periphery, and the air outlets 205 are provided with a wind guide protective cover 3 outside. The upper side of the air outlet seat 2 is provided with a cover plate 201 that can be flipped open.

[0068] like Figure 5 As shown, in this embodiment, the air guide shield 3 serves as the main exhaust channel, and it is inclined downwards at an angle of 20° to 45° with respect to the horizontal direction, such as... Figure 4 As shown, this allows the air guide shield 3 to be aligned with the exhaust direction of the fan 4 as much as possible, while also effectively preventing rainwater backflow.

[0069] like Figure 5 As shown, a filter assembly 206 is provided at the end of the air outlet 205 to achieve filtration and protection, thereby preventing external impurities from entering the interior of the prefabricated substation. In this embodiment, the filter assembly 206 can be made of multiple layers of filter protection, such as filter mesh or stainless steel wire mesh, as needed, thereby ensuring that the overall protection level of the invention reaches IP55.

[0070] like Figures 1-3 As shown, in this embodiment, one side of the cover plate 201 is rotatably connected to one side of the air outlet seat 2 (e.g., via a hinge). Both ends of the air outlet seat 2 are equipped with retractable cover plate driving devices 202. One end of the cover plate driving device 202 is rotatably mounted on a hinge seat on the corresponding inner wall of the air outlet seat 2, and the other end is rotatably connected to the cover plate 201 via a hinge shaft. When the cover plate driving device 202 extends, it drives the cover plate 201 to open; when it retracts, it drives the cover plate 201 to close. When the cover plate 201 is closed, the cover plate driving device 202 lies flat within the air outlet seat 2. The cover plate driving device 202 can be a hydraulic rod or similar device as needed.

[0071] In this embodiment, a sealing element is provided at the upper opening edge of the air outlet seat 2. When the cover plate 201 is closed, it is tightly attached to the sealing element to ensure a seal. In this embodiment, the sealing element can be a foam strip. After the cover plate 201 is closed, it contacts the foam strip and compresses the foam strip appropriately, thereby achieving the purpose of sealing the top of the air outlet seat 2.

[0072] like Figure 2 As shown in this embodiment, the cover plate 201 is provided with a handle 2011 to facilitate the operator to hold it according to actual needs.

[0073] like Figure 4 As shown, in this embodiment, the lower end of the air outlet seat 2 can be welded and fixed to the box cover 1, which is located above the box-type substation. Additionally, the box cover 1 is provided with an air guide duct 101, which is located below the corresponding fan 4. The air guide duct 101 has a tapered structure that is narrower at the top and wider at the bottom, which can better drive the gas flow and improve exhaust efficiency.

[0074] like Figure 2 As shown, in this embodiment, the air outlet seat 2 is divided into multiple fan chambers by fan partitions 204, and the fans 4 are located in the corresponding fan chambers. Each corner of the fan chamber is provided with a wind-blocking baffle 203, which can effectively prevent wind blockage at the corners of the fan chambers, thus preventing heat accumulation. In addition, the present invention utilizes the fan partitions 204 to form multiple independent fan chambers in the air outlet seat 2, and each fan 4 is connected to a corresponding air guide duct 101 below, which can avoid mutual interference between the fans 4 during operation, especially the formation of gas turbulence that affects the operation of the fans.

[0075] like Figures 1-2 As shown, the present invention changes the conventional top air outlet of the fan to the circumferential air outlet of the air outlet seat 2. This can increase the air outlet rate of the fan 4 and also ensure the air outlet area, thereby reducing the number of fans 4. However, due to the change in the air outlet direction, the present invention needs to adopt a new design method to rationally design the structure, especially to rationally determine the number of fans 4 in the present invention. After the number of fans 4 is determined, the air outlet seat 2 and other components are then designed in accordance with the number of fans 4.

[0076] like Figure 6 As shown, the design method of the present invention includes the following steps:

[0077] Step 1: Determine the total heat loss P of the transformer inside the box-type substation according to the following formula (1). loss (Unit: W):

[0078] P loss =P0+P K (1);

[0079] In the above formula (1), P0 is the no-load loss of the transformer (unit W), P K Transformer load loss (unit: W). P0 and P K All of these can be obtained directly from the transformer nameplate or factory test report.

[0080] Step 2: Determine the allowable temperature rise ΔT (in K) according to the following formula (2):

[0081] ΔT = T1 - T2 (2);

[0082] In the above formula (2), T1 is the allowable operating temperature of the transformer inside the box-type substation, and T2 is the highest ambient temperature around the box-type substation.

[0083] Step 3: According to the principle of heat balance, the heat carried away by the air flowing through the transformer should be equal to the total heat loss generated by the transformer. Therefore, the theoretical ventilation volume Q can be determined according to the following formula (3). V (Unit: m³ / s)

[0084] Q V = P loss / (ρ×c p ×ΔT) (3;

[0085] In equation (3) above, ρ is the air density (unit: kg / m³), which is taken as 1.205 kg / m³ under standard conditions, and c p The specific heat capacity of air at constant pressure (unit: J / (kg·K)) is taken as 1005 J / (kg·K);

[0086] Additionally, this step requires Q to be... V Unit conversion to m³ / h, i.e.:

[0087] Q h =3600×Q v ;

[0088] Step 4: Determine the safety factor and the design ventilation volume Q design .

[0089] This invention takes into account that measures such as the air guide shield 3 and filter assembly 206 will cause airflow loss (usually 10% to 30%), therefore, the theoretical ventilation volume Q needs to be reduced. V Multiply by the safety factor K S :

[0090] Q design =K S ×Q h (4);

[0091] In equation (4) above, the safety factor K S The value range is 1.2 to 1.5.

[0092] Step 5: Determine the wind speed v in the ventilation duct of the box-type substation according to the following formula (5):

[0093] v=Q design ’ / A OUT (5);

[0094] In equation (5) above, A OUT Q is the total cross-sectional area of ​​the wind guide shield 3. design ’ =Q design / 3600 is used to convert the wind speed unit from m³ / h back to m³ / s.

[0095] Step 6: Determine the total resistance loss ΔP of the ventilation duct of the box-type substation according to the following formula (6). total :

[0096] ΔP total =ΔP f +ΔP j (6);

[0097] In equation (6) above, ΔP f The friction loss is determined according to the following formula (7):

[0098] ΔP f =λ×(L / D h )×(ρ×v 2 / 2) (7)

[0099] In the above formula (7), λ is the friction coefficient, which is determined according to the specifications of the metal duct, and its acquisition is a well-known technique in this field (e.g., referring to relevant design manuals), L is the duct length (in meters), and D h ρ is the hydraulic diameter of the duct (in meters), the wind speed v in the duct is determined according to the above formula (5), and ρ is the air density.

[0100] In equation (6) above, ΔP j The local resistance loss is determined according to the following formula (8):

[0101] ΔP j =ξ×(ρ×v 2 / 2) (8;

[0102] In the above formula (8), ξ is the local resistance coefficient, including the local resistance coefficient ξ1 formed by the equivalent 90° duct bend and the local resistance coefficient ξ2 formed by the equivalent conical air guide tube;

[0103] Among them, such as Figure 5Since all air outlets 205 are horizontally arranged, the air outlets 205 on the same side can be considered as a 90° equivalent duct bend, and the cross-sectional area of ​​the equivalent duct bend is equal to the sum of the cross-sectional areas of the air outlets 205 on the corresponding side. Figure 4 As shown, the lower end of the air outlet seat 2 and the box-type substation can be regarded as an integral equivalent conical air duct.

[0104] The method of this invention is described in step eight below. First, a reasonable and reliable total pressure P of the fan needs to be determined. fan The method of this invention, through the aforementioned equivalent design, facilitates calculations. The 90° duct bend is a well-known structure in the art, and its local resistance coefficient ξ1 is a well-known and easily obtained technique (e.g., by referring to relevant design manuals). Furthermore, without determining the final number of fans 4 and the corresponding number of air ducts 101, the lower end of the outlet seat 2 and the interior of the box-type substation are approximately equivalent to an equivalent conical air duct. This has minimal impact on the final calculation results. Moreover, in step eight below, the total fan pressure P is determined... fan In addition, sufficient safety margin needs to be reserved, so that it is convenient for calculation and can also meet the design requirements. The upper and lower end areas of the equivalent conical air guide are set according to the lower end area of ​​the actual air outlet seat 2 and meet the structural requirement of being narrower at the top and wider at the bottom. The upper end area of ​​the equivalent conical air guide must be smaller than the lower end area of ​​the air outlet seat 2.

[0105] Step 7: Consider the additional resistance ΔP of filter component 206. filter The final total drag loss ΔP is determined according to the following formula (9). total ’ :

[0106] ΔP total ’ =ΔP total +ΔP filter (9);

[0107] Step 8: Determine the total pressure P of the fan according to the following formula (10). fan :

[0108] P fan ≥ΔP total ’ (10);

[0109] In equation (10) above, P fan Sufficient safety margin should be reserved according to the actual situation.

[0110] Step 9: Determine the fan verification shaft power N according to the following formula (11):

[0111] N = (Q) design’ ×P fan ) / (η fan ×1000) (11)

[0112] In equation (11) above, η fan For the efficiency of the vortex fan, η fan The value is typically 0.5 to 0.8.

[0113] Step 10: Determine the number n of fans 4 and verify the total power, where:

[0114] n= Q design / Q single (12);

[0115] In equation (12) above, Q design Q is obtained in step four. single The rated air volume (m³ / h) for a single fan 4;

[0116] Then check the total power according to the following formula (13):

[0117] n×N single ≥N (13);

[0118] In the above equation (13), N single N represents the power of a single 4-shaft fan, and N is the power of the fan verification shaft determined in step nine.

[0119] Once the number of fans (n) is determined, as follows: Figures 1-2 As shown, the present invention can determine the number of fan chambers in the fan seat 2 and carry out related structural design.

[0120] The following application example further illustrates the design method of the present invention:

[0121] Application Example 1:

[0122] The relevant known parameters of the prefabricated substation in this application example are shown in the table below:

[0123] parameter Value illustrate Transformer rated capacity 2000 kVA Single transformer inside the box-type substation <![CDATA[No-load loss P0]]> 2.5 kW Transformer nameplate acquisition <![CDATA[Load Loss P k > 6.0 kW Transformer nameplate acquisition (100% load rate) Ambient temperature 40℃ Maximum ambient temperature Allowable internal temperature of transformer substation 55℃ Transformer operating allowable temperature Duct length L 3.0 m From the internal positioning of the transformer substation to the air outlet <![CDATA[Hydraulic diameter of air duct D h > 0.3 m Calculation based on duct cross-section Equivalent number of duct bends 2 The local resistance coefficient of a single elbow is ξ = 1.0. Equivalent conical air guide 1 The local drag coefficient ξ of the tapered variable diameter is 0.3. Friction coefficient λ 0.03 Determined based on metal air duct air density ρ 1.205 kg / m³ Standard State <![CDATA[Specific heat capacity of air c p > 1005 J / (kg·K) Standard State <![CDATA[Fan efficiency η fan > 0.65 Typical values ​​of vortex blowers <![CDATA[Safety Factor K s > 1.3 Considering filter resistance and performance degradation <![CDATA[additional resistance of filtration ΔP filter > 50 Pa Obtained from filter component samples

[0124] The specific design process for this application example is as follows:

[0125] Step 1: Determine the total heat loss P of the transformer inside the prefabricated substation. loss :

[0126] P loss =P0+P K =2.5+6.0=8.5kW=8500W (1);

[0127] Step 2: Determine the allowable temperature rise ΔT:

[0128] ΔT = T1 - T2 = 55 - 40 = 15K (2);

[0129] Step 3: Determine the theoretical ventilation volume Q V :

[0130] Q V =8500 / (1.205×1005×15)=8500 / 18165≈ 0.468 m³ / s (3);

[0131] Then Q V Unit conversion to m³ / h, i.e.:

[0132] Q h =3600×0.468 m³ / s =1685 m³ / h ;

[0133] Step 4: Determine the design ventilation volume Q design .

[0134] Q design =K S ×Q h =1.3×1685=2190 m³ / h (4);

[0135] Step 5: Determine the wind speed v in the ventilation duct of the prefabricated substation, where the total cross-sectional area A of the wind guide shield 3 used in this application example is... OUT =0.16 m 2 :

[0136] v=Q design ’ / A OUT =(2190 / 3600) / 0.16=0.608 / 0.16=3.8m / s (5);

[0137] Step 6: Determine the total resistance loss ΔP of the ventilation duct in the prefabricated substation. total Specifically:

[0138] First calculate the friction loss ΔP along the friction path. f and local resistance loss ΔP j :

[0139] ΔP f =λ×(L / D h )×(ρ×v 2 / 2)=0.03 × (3.0 / 0.3) × (1.205 × 3.8² / 2) =0.3 × 8.70 ≈ 2.61 Pa (7);

[0140] ΔP j =ξ×(ρ×v 2 / 2) =2.3 × (1.205 × 3.8² / 2) = 2.3 × 8.70 ≈ 20.0 Pa (8);

[0141] In the above formula (8), the local resistance coefficient ξ includes the local resistance coefficient ξ1=1.0 formed by the equivalent 90° duct bend and the local resistance coefficient ξ2=0.3 formed by the tapered diameter change of the equivalent tapered air guide. In this application example, the air outlets 205 located on both sides of the air outlet seat 2 are equivalent to two 90° equivalent duct bends. Therefore, the total local resistance coefficient ξ in this application example is ξ1×2+ξ2=1.0×2+0.3=2.3.

[0142] Then calculate the total drag loss ΔP total :

[0143] ΔP total =ΔP f +ΔP j = 2.61 Pa +20.0 Pa =22.61 Pa (6);

[0144] Step 7: Consider the additional resistance ΔP from the filter. filter Determine the final total drag loss ΔP total ’ :

[0145] ΔP total ’ =ΔP total +ΔP filter = 22.61 +50=72.61 Pa (9);

[0146] Step 8: Determine the total pressure P of the fan according to the following formula (10). fan :

[0147] P fan ≥ΔP total ’ (10);

[0148] In this application example, to ensure sufficient safety margin, P is selected. fan =100 Pa > 72.61 Pa meets the requirements of formula (10) above.

[0149] Step 9: Determine the fan verification shaft power N:

[0150] N = (Q) design ’ ×P fan ) / (η fan ×1000)=(0.608 × 100) / (0.65 × 1000)=60.8 / 650≈0.094 kW (11);

[0151] Step 10: Determine the number of fans 4 and verify the total power. In this application example, the rated air volume Q of a single vortex fan is selected. single =550 m³ / h, single shaft power N single =0.12 kW:

[0152] n= Q design / Q single =2190 / 550=3.98 (12);

[0153] Take an integer value for n, where n = 4 units;

[0154] Then check the total power:

[0155] n×N single =4×0.12=0.48 kW≥N=0.094 kW (13);

[0156] The verification meets the requirements.

Claims

1. A top-mounted air outlet structure for a box-type substation with circumferential air outlet, characterized in that: Includes a box cover (1), and the box cover (1) is provided with an air outlet seat (2), the air outlet seat (2) is provided with a fan (4) inside, the air outlet seat (2) is provided with multiple air outlets (205) on the outer periphery, and the air outlets (205) are provided with a downwardly inclined air guide shield (3) outside, and the air outlets (205) are provided with a filter assembly (206) at the end; the upper side of the air outlet seat (2) is provided with a cover plate (201) that can be flipped open.

2. The top air outlet structure of the box-type substation with circumferential air outlet as described in claim 1, characterized in that: The air guide shield (3) is inclined downward at an angle of 20° to 45° with the horizontal direction.

3. The circumferentially ventilated box-type substation top ventilation structure according to claim 1, characterized in that: One side of the cover plate (201) is rotatably connected to one side of the air outlet seat (2). Both ends of the air outlet seat (2) are provided with a retractable cover plate driving device (202), and the cover plate (201) is driven to flip by the cover plate driving device (202).

4. The circumferentially ventilated box-type substation top ventilation structure according to claim 3, characterized in that: One end of the cover plate driving device (202) is rotatably mounted on the hinge seat on the inner wall of the corresponding side of the air outlet seat (2), and the other end is rotatably connected to the cover plate (201) through the hinge shaft.

5. The circumferentially ventilated box-type substation top ventilation structure according to claim 3, characterized in that: The upper opening edge of the air outlet seat (2) is provided with a sealing element, and the cover plate (201) is in close contact with the sealing element when closed.

6. The top air outlet structure of the box-type substation with circumferential air outlet according to claim 1, characterized in that: The cover (1) is provided with an air guide (101), and the air guide (101) is located below the corresponding fan (4). The air guide (101) is a conical structure that is narrow at the top and wide at the bottom.

7. The circumferentially ventilated box-type substation top ventilation structure according to claim 1, characterized in that: The air outlet seat (2) is divided into multiple fan chambers by a fan partition (204), and the fan (4) is located in the corresponding fan chamber.

8. The top air outlet structure of the box-type substation with circumferential air outlet according to claim 7, characterized in that: Each corner of the fan chamber is equipped with a windproof baffle (203).

9. A design method for a top-mounted air outlet structure of a box-type substation with circumferential air outlet as described in claim 6, comprising the following steps: Step 1: Determine the total heat loss P of the transformer inside the box-type substation according to the following formula (1). loss : P loss =P0+P K (1); In equation (1) above, P0 is the no-load loss of the transformer, P K For transformer load losses; Step 2: Determine the allowable temperature rise ΔT according to the following formula (2): ΔT = T1 - T2 (2); In the above formula (2), T1 is the allowable operating temperature of the transformer inside the box-type substation, and T2 is the highest ambient temperature around the box-type substation. Step 3: Determine the theoretical ventilation volume Q according to the following formula (3). V : Q V = P loss / (ρ×c p ×ΔT) (3); In equation (3) above, ρ is the air density, and c p The specific heat capacity of air at constant pressure; Additionally, this step requires Q to be... V Unit conversion to m³ / h, i.e.: Q h =3600×Q v ; Step 4: Determine the safety factor K S And obtain the design ventilation volume Q design ,in: Q design =K S ×Q h (4); In equation (4) above, K S The value range is 1.2 to 1.5; Step 5: Determine the wind speed v in the ventilation duct of the box-type substation according to the following formula (5): v=Q design ’ / A OUT (5); In equation (5) above, A OUT Q is the total cross-sectional area of ​​the wind guide shield (3). design ’ =Q design / 3600; Step 6: Determine the total resistance loss ΔP of the ventilation duct of the box-type substation according to the following formula (6). total : ΔP total =ΔP f +ΔP j (6); In equation (6) above, ΔP f The friction loss is determined according to the following formula (7): ΔP f =λ×(L / D h )×(ρ×v 2 / 2) (7); In equation (7) above, λ is the friction coefficient, L is the duct length, and D is the friction factor. h The hydraulic diameter of the air duct; In equation (6) above, ΔP j The local resistance loss is determined according to the following formula (8): ΔP j =ξ×(ρ×v 2 / 2) (8); In equation (8) above, ξ is the local drag coefficient; Step 7: Consider the additional resistance ΔP of the filter assembly (206) filter The final total drag loss ΔP is determined according to the following formula (9). total ’ : ΔP total ’ =ΔP total +ΔP filter (9); Step 8: Determine the total pressure P of the fan according to the following formula (10). fan : P fan ≥ΔP total ’ (10); Step 9: Determine the fan verification shaft power N according to the following formula (11): N=(Q design ’ ×P fan ) / (or fan ×1000) (11); In equation (11) above, η fan For fan efficiency; Step 10: Determine the number n of fans (4) and verify the total power, where: n= Q design / Q single (12); In equation (12) above, Q single The rated air volume of a single fan (4); Then check the total power according to the following formula (13): n×N single ≥N (13); In the above equation (13), N single The shaft power of a single fan (4).

10. The design method for the top air outlet structure of a box-type substation with circumferential air outlet according to claim 9, characterized in that: In step six, the local resistance coefficient ξ includes the local resistance coefficient ξ1 formed by the 90° equivalent air duct bend and the local resistance coefficient ξ2 formed by the equivalent conical air guide tube. Each air outlet (205) located on the same side is regarded as a 90° equivalent air duct bend, and the cross-sectional area of ​​the equivalent air duct bend is equal to the sum of the cross-sectional areas of each air outlet (205) on the corresponding side. The lower end of the air outlet seat (2) and the box-type substation are regarded as an equivalent conical air guide tube.

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