The following is the relevant content about underground garage ventilation and smoke prevention and exhaust design brought to you by Zhongda Consulting for your reference.
1. Types and hazards of harmful substances in underground parking lots
The harmful substances emitted by cars in underground parking lots are mainly carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOX) and other harmful substances. They originate from the crankcase and exhaust system. The pollutants in fuel tanks and carburetors are mainly hydrocarbons (HC), which are formed from fuel gas. If not well controlled, the pollutants will account for 15% to 20% of the total pollutants; the pollutants leaked from the crankcase have similar composition to automobile exhaust, and the main harmful substances are CO, HC, (NOX), etc. Some gasoline contains tetraethyl lead as an antiknock agent, causing the exhaust gas to contain a large amount of lead, which is 100 times more toxic than organic lead and is very harmful to human health and safety. Its manifestations are as follows: p>
(1) Carbon monoxide is the gas that is most easily poisoned and has the most poisoning cases. It is the product of incomplete combustion of carbon. When a person inhales carbon monoxide, it is absorbed through the lungs and enters the bloodstream. Because the affinity between carbon monoxide and hemoglobin is 210 times greater than that of oxygen, carbon monoxide quickly forms carboxyhemoglobin, which hinders the ability of hemoglobin to transport oxygen, leading to severe hypoxia and poisoning.
(2) A large amount of nitrogen oxide compounds (NOX) discharged into the air can also cause people to be poisoned, causing damage to mucous membranes, absorption tracts, nervous systems, and hematopoietic systems.
(3) The most toxic aromatic hydrocarbons in gasoline hot gas are aromatic hydrocarbons. The content of aromatic hydrocarbons in various brands of gasoline is generally 2% to 16%. When people inhale gasoline vapor, it can cause special irritation (such as anesthesia). When the poisoning is severe, it can cause people to lose consciousness and cause convulsions.
(4) There is a danger of flammability and explosion. The explosion limit of gasoline is 2.5% as the lower limit and 4.8% as the upper limit. When the carbon monoxide content in the air is 15% to 75%, carbon monoxide will also explode.
At idle speed, the ratio of the emission of three harmful substances, CO, HC, and NOX, is approximately 7:1.5:0.2. It can be seen that CO is the main one. According to TT36-79 "Hygienic Standards for Design of Industrial Enterprises", as long as sufficient fresh air is provided and the CO concentration in the air is diluted below the range specified in the "Standards", both HC and NOX can meet the requirements of the "Standards".
2. Calculation of garage area
Minus first floor: left half
Garage area (81800-8100)x(43204000)+3900x8100x2=3541.82 m2
Total construction area 81800x(43204000)+(8108106900)x4200-8100x5100
=3916.67m2
Right half
Garage area (6600x2+8104800)x(79700-8100)+(6000x2+8100)x6000-8100x4800=1950.48m2
Total building area (43208100)x(8100x5+ 6800)+(8100x4)x(4806600x2+51008106000)+(1505100)x(6600x2+8104800)
=3804.03m2
Negative The total construction area on the first floor is 3916.67+3804.03=7720.7m2
The second floor below: left half
The total construction area is 81800x43200-(5104203900)x5100-(6908100) x5100
=3389.94m2
Garage area (43200-8100-3000) x (81800-5100-4200-3900)+8100x3900
=2233.65m2< /p>
Right half
The total construction area is the same as the first floor below
The garage area (6608106604800)x79705100x(8106800)+( 6000x2+8100)x(8100x3)-(4000x43204000x5100)
=2451.39m2
The total construction area of ??the negative second floor is the same as that of the negative first floor.
3. Determination of air supply volume and exhaust volume
Underground garages are considered based on comprehensive ventilation design, and the required ventilation volume can be calculated according to the formula. The ventilation volume required for comprehensive ventilation is:
L0=LM (m3/h) L=Q/C-CO (m3/h)
In the formula: L0-garage exhaust Amount (m3/h); L-garage exhaust volume per unit floor area (m3/h); M-car storage area (m2); Q-car CO emissions per unit floor area (mg/h-m2); C- The allowable concentration of CO in the parking lot, C=100mg/m3; CO-CO content in the outdoor atmosphere, CO=3.0mg/m3;
Car CO emissions per unit ground area (mg/h-m2 ): Q=ABCD/E
In the formula: A-the number of parking spaces per unit of the garage; B-the frequency of car entry and exit (the ratio of the number of entries and exits per hour to the design capacity), which can be 50~100% ; C-The engine running time of each car in the garage is 3 minutes; D-Car CO emissions per unit time, g/s. The CO emission of the domestically produced Santa Claus is 0.577g/s, and the CO emission of the imported Ford automobile is 0.319g/s; E----The percentage of CO emissions in the total emissions is 0.89.
1. Car exhaust emissions in underground parking lots
The total rear emissions of cars parked in underground parking lots are not only related to the car model, number of parking spaces, parking space utilization coefficient, and displacement per unit time It is related to the working time of the car engine in the garage and to the exhaust temperature. The data in Table 1 are data when the exhaust temperature is 550°C (domestic cars) and 500°C (imported cars). When detecting the concentration of harmful gases emitted by cars, the rear temperature is around 20°C at normal temperature. A temperature correction should be made for this purpose.
The calculation formula is
Qi=T2WSBiDit10-3/T1,m3/hQ=ΣQi,m3/hi=1
where Q---car exhaust in the underground parking lot Total amount, m3/h
Qi---The total exhaust amount of category i cars in the parking lot is usually selected according to the 4 categories in Table 1 (domestic cars and vans, imported cars and vans ), m3/h;
S---The parking space utilization coefficient of the garage, that is, the ratio of the number of parking vehicles to the number of parking spaces per unit time, its value is given by
W- --The total number of parking spaces in the Diyi parking lot, units;
Bi---The exhaust volume per unit time of class i cars, 1/min per unit, can be found in Table 1;
Di---the percentage of category i to the total parking volume;
t---the working time of each vehicle in the underground parking lot, generally the average value is t=6min;
p>T1---Car exhaust temperature, K,
Domestic car T1=825K
Imported car T1=773K;
T2 ---The air temperature in the underground parking lot is generally taken as T2 = 293K.
2. The CO emissions in the underground parking lot can be calculated by the following formula
G=ΣQiCi,m3/hi=1
Where G--- The amount of CO produced in the underground parking lot, mg/h;
The average concentration of CO emitted by Gi---i class vehicles, mg/m3, is found in Table 1.
3. CO concentration in the atmosphere above the underground parking lot
When calculating the exhaust volume of the underground parking lot, the CO concentration in the atmosphere above the underground parking lot, the actual measured value is 2.71～3.23mg/m3, 2.5～3.5mg/m3 is preferable in design.
4. Calculation of air supply volume
In order to prevent the escape of harmful gases in underground parking lots, it is required to maintain a certain negative pressure in the parking lot. Therefore, the air supply volume of the underground parking lot is smaller than the exhaust air volume. According to experience, the general supply air volume is 85% to 95% of the exhaust air volume. The other 5% to 15% of the make-up air is supplemented by penetration into gaps in doors, windows, driveways, etc.
According to the exhaust volume calculation formula, the exhaust volume of each parking space is calculated according to the underground parking space and listed in Table 2. Therefore, as long as you know the number of parking spaces and car types in the underground parking lot, and then determine an S, you can easily and simply calculate the exhaust volume of the underground parking lot based on Table 2.
Note: Calculation conditions C-CO=100-3=97 (mg/m3)
Calculation of exhaust air volume and air supply volume on the negative floor:
Assume that the domestic car is the total 40% of the parking spaces, 20% for domestic vans, 20% for imported cars, 20% for imported vans, take S=1.00
The exhaust volume of domestic cars L1=741.62x191x40%=56660m3/h< /p>
Domestic van exhaust volume L2=666.12x191x20%=25445.78m3/h
Imported car exhaust volume L3=448.16x191x20%=17119.7m3/h
Imported van exhaust volume L4=534.51x191x20%=20418.3m3/h
Then the total exhaust volume L=L1+L2+L3+L4=119643.78m3/h
The air supply volume is 85% to 95% of the exhaust air volume, so the air supply volume L=119643.78x90%=107679.4m3/h
Calculation of the exhaust air volume and air supply volume of the negative second floor:
The exhaust volume of domestic cars L1=741.62x176x40%=52210.05m3/h
The exhaust volume of domestic vans L2=666.12x176x20%=23447.42m3/h
Imported small cars Car exhaust air volume L3=448.16x176x20%=15775.22m3/h
Imported van exhaust air volume L4=534.51x176x20%=18814.77m3/h
Then the total exhaust air volume L =L1+L2+L3+L4=110247.68m3/h
Air supply volume L=110247.68x90%=99222.9m3/h
IV. Air flow distribution in underground garage
When considering the air flow distribution in an underground garage, preventing local stagnation in the site is the most important issue. Because CO is lighter than air, and the engine heats up, the air flow tends to stagnate in the upper part of the garage, so it is beneficial to exhaust the air at the ceiling, and the exhaust position of the car is at the lower part of the garage. It would be better if it could be drained directly from the bottom before it spreads. In addition, gasoline vapor is heavier than air, and it is also desirable to exhaust air from the bottom, so the exhaust air should be discharged from the top to the bottom. General technical manuals require 1/3 of the upper row and 2/3 of the lower row. The exhaust outlets should be arranged evenly and as close to the car body as possible. If the fresh air can be sent from the lower part of the garage, it will be very beneficial to reduce the CO concentration, but it is structurally difficult to achieve. Therefore, the air supply outlets can be concentrated in the upper part, using the middle supply and return on both sides, or both sides. Back.
5. Ventilation system design
The design of the underground garage ventilation system must not only consider ventilation, but also consider fire prevention and smoke exhaust issues. If the ventilation and fire and smoke prevention of the garage are arranged separately, the system design is simple due to their single functions. If combined with the arrangement, the system design becomes complicated, but this complex system is technically feasible and economically reasonable, so it is commonly used.
There are two forms of ventilation and smoke exhaust systems:
(1) A system main pipe is installed at the upper part of the multi-branch system garage, and the downward risers are evenly connected from the main pipe. The lower part of the standpipe is equipped with an exhaust outlet. The exhaust outlet on the main pipe also serves as a smoke exhaust outlet. An ordinary exhaust outlet is provided. The exhaust outlet on the branch pipe is only used as an exhaust outlet. A smoke and fire damper is installed. As shown in the picture. Normally, the upper and lower exhaust vents exhaust air at the same time; in the event of a fire, the smoke and fire dampers in the lower exhaust vents automatically close, and the upper exhaust vents serve as smoke exhaust vents to remove smoke. If multiple risers are connected to the main pipe, each riser will be small in size and therefore occupy a small space. However, each riser is equipped with a smoke and fire damper, which not only requires a large initial investment, but also tends to cause loss of control and miscontrol due to the large number of valves, affecting the effectiveness of system operation.
1. Single-speed exhaust/smoke exhaust fan 2. Smoke exhaust fire damper 3. Smoke prevention fire damper 4. Air exhaust/smoke exhaust outlet 5. Exhaust outlet
（ 2) Single branch pipe system
The upper part of the garage is equipped with a system main pipe, and a branch pipe is connected from the main pipe. The branch pipe forms a horizontal pipe at the lower part. The main pipe and the riser pipe are evenly equipped with ordinary exhaust outlets. Install fire and smoke dampers near the main pipe. The layout is as shown below.
Normally, the upper and lower exhaust vents exhaust air at the same time; in the event of a fire, the smoke and fire dampers on the branch pipes automatically close, and the upper exhaust vent serves as a smoke exhaust port. If only one riser is connected to the main pipe, only one smoke prevention and fire damper can meet the smoke exhaust needs in case of fire. The control is simpler than the previous solution, and the initial investment is low, but it takes up a lot of space.
1.Single-speed exhaust/smoke exhaust fan 2.Smoke exhaust fire damper 3.Smoke fire damper 4.Air/smoke exhaust outlet 5.Exhaust outlet
Passed In comparison, it is more reasonable to choose the second option. Because the garage area is large, this option is economical and convenient.
6. Hydraulic calculation of exhaust duct
(1) The layout of the left half pipe section on the negative floor and the pipe number and length labeling are as shown in the figure. The most unfavorable loop is determined to be:
Because the two parts AB are basically symmetrical and can be arranged in the same way, only the fan A and its pipeline are calculated.
Part A: The most unfavorable loop is 1-2-3-4-5-6-7-8-9-10-11.
(2) Based on the air volume of each pipe section and the selected flow rate, determine the cross-sectional dimensions of each pipe section of the most unfavorable loop and the resistance and local resistance along the way as follows:
Take the flow velocity in the pipe V1-2=4.0m/s, the design total exhaust volume P=119643.78m3/h, so the air outlet area S=P/V=119643.78/(4X3600)=8.31m2 The design number of air outlets is n=49, and the air volume of each air outlet P1=119643.78/49=2441.7m3/h=0.678m3/sS1=S/n=8.31/49=0.17m2
The size of the rectangular air outlet is 400X400mm2
Pipe section 1-2: The end air duct is 400X400mm2. The actual area S1=0.16m2
So the actual flow velocity V=4.24m/s
The equivalent diameter D=2x400x400/(40400)=400mm actual flow velocity It is 4.24m/s
Check "Civil Building Air Conditioning Design" P208 Figure 7-1 and get Rm1-2=0.5Pa/m
ΔPm1-2=0.5x8.1=4.05 Pa
Calculation of local resistance: (Check the "Practical Ventilation and Air Conditioning Duct Calculation Method" P279)
① If the average wind speed of the movable louver air outlet is 3.0m/s, then the air outlet area f =2441.7/(3600x3)=0.226m2 and the actual air duct size is 500X450mm2, so the actual flow velocity is 3.014m/s. Check Appendix 5 of "Ventilation Engineering" to find that when the local resistance coefficient ξ=2.0, V=3.0m/s, corresponding to the flow velocity in the pipe V=3.014/0.8=3.768m/s (assuming the effective area is 80%)
② Gradually expanding pipe F1/F0=500X450/400X400=1.41 Take the gradually expanding angle of 30° to interpolate and check the appendix of "Ventilation Engineering" 5
It is found that ξ=0.108 corresponds to the flow velocity V=3.014m/s
③When the multi-leaf split air volume regulating valve is pressed at 0°, it is found that ξ=0.52
④Rectangular air duct round elbow: b/h=1R/b=1, get ξ=0.29
⑤Rectangular air duct confluence four-way (θ=90°) after the confluence, the flow rate of the pipe section is 2441.7X3=7325.1 m3/h
The preliminary flow rate V=6m/sS=0.34m2 The pipe size is 630x500mm2. The actual flow rate is 6.46m/s
Check from A3/A1=400x400/630x500=0.51 The table shows that ξ=0.2 corresponds to the flow velocity V=6.46m/s
(3) The calculation method for other pipe sections is the same as above
(4) Calculation results
(5) Calculation of total system resistance and fan selection
The total system resistance is the sum of the resistances of the most unfavorable loops 1-2-3-4-5-6-7-8-9-10-11, which is 24.85+ 16.95+19.54+18.02+17.572+17.085+29.18+33.52+34.54+3.2=214.46Pa
Fan air volume: Lf=1.15L=1.15x2441.7x17=47735.235m3/h
Fan pressure: Pf=1.15xP=1.15x214.46=246.63Pa
Optional XPZ-I fire smoke exhaust fan model 11 impeller diameter 11100MM recommended working condition air volume 48500m3/h
Recommended operating conditions: Full pressure 690Pa, rotation speed 960r/min, installed capacity 15KW
A sound level <=92dB weight 380KG
Two units are arranged on the left side of each floor, symmetrically arranged. ***Requires four units.
(6) The layout of the right half of the pipe section on the negative floor and the pipe numbers and lengths are shown in the figure. The most unfavorable loop is determined to be:
Part C: The most unfavorable loop is 1-2-3-4-5-6-7-8-9-10.
(7) Based on the air volume of each pipe section and the selected flow rate, determine the cross-sectional size of each pipe section of the most unfavorable loop and the resistance along the way and the local resistance as follows:
Take the flow velocity in the pipe V1-2=4.0m/s
Pipe section 1-2: The end duct is 400X400mm2. The actual area S1=0.16m2
So the actual flow velocity V=4.24m/s
p>Equivalent diameter D=2x400x400/(40400)=400mm. The actual flow velocity is 4.24m/s
Check "Civil Building Air Conditioning Design" P208 Figure 7-1 and get Rm1-2=0.47 Pa/m
ΔPm1-2=0.47x12.15=5.71Pa
Local resistance calculation: (Check the "Practical Ventilation and Air Conditioning Air Duct Calculation Method" P279)
① If the average wind speed of the movable louver air outlet is 3.0m/s, then the air outlet area f=2441.7/(3600x3)=0.226m2 and the actual air duct size is 500X400mm2, so the actual flow speed is 3.39m/s. Check "Ventilation Engineering" Appendix 5 shows that when the local resistance coefficient ξ=2.0, V=3.39m/s, corresponding to the flow velocity in the pipe V=3.39/0.8=4.24m/s (assuming the effective area is 80%)
② Gradually expanding pipe F1/ F0 = 500 When the split air volume control valve is pressed at 0°, the result is ξ=0.52
④Rectangular air duct round elbow: b/h=1R/b=1, the result is ξ=0.21
⑤ The combined flow rate of the rectangular air duct four-way (θ=90°) is 2441.7 /s
Looking up the table from A3/A1=400x400/630x500=0.51, we get that ξ=0.05 corresponds to the flow velocity V=6.46m/s
(8) The calculation method for other pipe sections is the same as above
p>(9) Calculation results
(10) Calculation of total system resistance and fan selection
The total system resistance is the most unfavorable loop 1-2-3-4 -The sum of 5-6-7-8-9-10 resistance, that is, 221.12Pa fan air volume: Lf=1.15L=1.15x2441.7x16=44927.28m3/h
Fan air pressure: Pf=1.15 xP=1.15x221.12=254.3Pa
Optional XPZ-I fire smoke exhaust fan model 10 impeller diameter 10000MM recommended working condition air volume 45679m3/h
recommended working condition full pressure 630Pa rotation speed 1450r/min installed capacity 11KW
A sound level <=90dB weight 300KG
One unit is arranged on the left side of each floor, two units are required.
7. Garage air supply and air supply and exhaust in other rooms outside the garage
1. Garage induction fan selection
The jet induction ventilation system uses the induction of jets Features, fresh air is introduced at the air supply outlet, and an ultra-thin jet is used to eject the mainstream air at high speed to induce and stir a large amount of surrounding air. On the one hand, it dilutes the harmful gases in the garage space, and on the other hand, it drives the air along the preset process. To the set direction, new air can be introduced at the air inlet and exhaust gas can be smoothly discharged at the exhaust outlet, ensuring a good ventilation effect in the garage space. This form is selected for the garage part, and the selection results are as follows:
Model: TOPVENT (JET/JDY) Air volume (m3/h): 600~750
Nozzle form: IⅡⅢ Range (m ): 151210
Boundary layer width (m): 6812 Induction ratio: 1:20
Power (W): 60 Voltage (V): 220
Noise dB(A): ≤45 Weight (kg): 30
Compared with traditional ventilation systems, the jet-induced ventilation system has a simple system without air ducts, low system cost, and low operating cost.
The exhaust gas is diluted by a large amount of fresh air, and the average concentration of the exhaust gas is reduced. It can effectively control the direction of air flow, the air is smooth, there are no stagnant corners, and the ambient air quality is good. Even if the main supply and exhaust fan stops running, the ejector can still make the air flow. Utilizing the space between floor slabs and beams, it is easy to cooperate with other pipelines, saving space, simple construction, and beautiful appearance. It can reduce floor height and civil construction costs. The air volume of the ejector is small, the static pressure of the main supply and exhaust fan is low, and the noise is greatly reduced. There are 15 units on each floor, evenly arranged.
2. Selection of induction fans in other rooms outside the garage:
YDF series induction fans
This series of fans uses aerodynamic principles to The disturbance characteristics of high-speed jet gas can effectively induce the surrounding still air, thereby driving the air flow; achieving high efficiency and energy saving, improving ventilation quality, saving space, and convenient installation and maintenance.
This series of fans is divided into two types: YDF-A type duct type and YDF-B type multi-blade type. Usage: Used in electric power, chemical industry, electronics, automobiles, papermaking, airports, hotels, restaurants, hospitals, office buildings, shopping malls, theaters, auditoriums, supermarkets, warehouses, industrial workshops, gymnasiums, exhibition halls, conference rooms, office buildings, High-end civil buildings and other occasions.
Model: YDF-A type
Machine number: 2.5#, 2.8#
Air volume: 3600, 6000m3/h
Full Voltage: 1736, 1760Pa
Noise: 87dB(A)
Power supply: 380V/50Hz
Model: YDF-B type
Machine number: 2.5#, 3#
Air volume: 680/850～985/1350m3/h
Range: 12～18Pa
Noise: 58～60dB (A)
Power supply: 220V/50Hz
The air supply in the power distribution room is 15 times/H and the exhaust air is 17.5 times/H. The air volume is large, so YDF-A is configured Type, one on the negative floor.
The water pump room supplies and exhausts air 5 times/H; the air conditioning machine room and fan room supply and exhaust air 3~5 times/H; the refrigeration machine room supplies air 5 times/H and exhausts 6 times/H; 4~6 times in non-air-conditioned rooms
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