Shanghai up Pa Ventilation Equipment Co., Ltd
The selection of the fan is generally carried out as follows:
1, calculate the amount of ventilation required to determine the tunnel;
Calculate the total thrust required
It = ΔP × At (N)
Where: At: tunnel cross-sectional area (m2)
△ P: the sum of the resistance (Pa); generally should be considered the following four:
1) tunnel inlet resistance and outlet resistance;
2) the resistance of the tunnel surface friction, suspension fan devices, brackets and road signs caused by the resistance;
3) traffic resistance;
4) the resistance between the inlet and the outlet due to the pressure difference between temperature, air pressure and wind speed.
3, to determine the overall arrangement of the fan
According to the length of the tunnel, the total thrust required and the range of thrust provided by the jet fan, it is tentatively determined that the m-group fan is arranged on the total length of the tunnel, and the thrust of each fan is T.
Satisfies the total thrust requirement of m × n × T ≥ Tt, taking into account the following restrictions:
1) n fan parallel, the centerline spacing should be greater than 2 times the fan diameter
2) m group (Taiwan) fan series, the vertical spacing should be greater than 10 times the diameter of the tunnel
4, a single fan to determine the parameters
The performance of the jet fan is measured by the thrust applied to the airflow. The thrust generated by the fan is theoretically equal to the momentum difference between the inlet and outlet airflow of the fan (the momentum is equal to the product of the mass flow rate and the flow rate). In the case of the fan test condition, Momentum is zero, so you can calculate the theoretical thrust of the fan under test conditions:
Theoretical thrust = p × Q × V = pQ2 / A (N)
P: Air density (kg / m3)
Q: air volume (m3 / s)
A: fan outlet area (m2)
The thrust of the test bench is usually 0.85-1.05 times the theoretical thrust, depending on the flow field distribution and the structure of the fan and the muffler. The fan performance data given in the graph are given by the test bench But the measurement thrust is not equal to the available thrust T in the tunnel, which is due to the effect of the unloading effect in the tunnel when the fan is hoisted in the tunnel (Kodak effect) , The available thrust is reduced, and the degree of influence can be expressed and calculated using the coefficients K1 and K2:
T = T1 × K1 × K2 or T1 = T (K1 × K2)
Where T: the jet fan installed in the tunnel can be used thrust (N)
T1: Test bench test thrust (N)
K1: Average airflow velocity in tunnel and influence factor of fan outlet wind speed on fan thrust
K2: Influence coefficient of the distance between the fan shaft and the tunnel wall
The following occasions the use of fan selection analysis
First of all, to see whether the storage of goods is flammable and explosive goods, such as: paint warehouses, etc., must choose explosion-proof series of fans. Second, look at the level of noise requirements, you can choose roof fan or environmentally friendly centrifugal fan, (and a roof fan is the wind start, but also can save power it
Finally, look at the size of the air required for storage air, you can choose the most conventional axial fan type fan or fan FA type.
First of all, for the indoor row of fumes in the kitchen (that is, the exhaust on the indoor wall), according to the size of fumes selected SF-type axial fan or FA-type exhaust fan.
Second, for the large smoke, and the need for long-term through the pipeline, and the pipeline has a curved handle the kitchen, it is strongly recommended to use centrifugal fan (4-72 centrifugal fan is the most common, 11-62 low noise environment-friendly centrifugal fan is also very practical) , This is because the centrifugal fan pressure is larger than the axial fan, and the fumes do not go through the motor, the motor maintenance and cleaning more easily. Finally, the proposed fumes strong kitchen selection of the above two programs and use, the effect is better.
High-end place ventilation
For the hotel, tea, coffee bar, chess room, karaoke OK and other high-end places ventilation, it is not appropriate to use a conventional fan.
First of all, for the ventilation of the room, so that the ventilation duct connected to the central ventilation duct room, can take into account the appearance and noise on the basis of choice FZY series of small axial fans, small size, plastic or aluminum appearance, low noise and high air volume coexist The
Secondly, the wind volume and noise requirements more stringent point of view, the wind box is the best choice. Inside the box has a silencer cotton, external central ventilation pipe can achieve significant effect of noise reduction.
Finally, add that for the gym indoor hair, be sure to choose the large amount of wind-type FS-type industrial fans, rather than SF-type post-axial fan. This is from the appearance and safety considerations.