The question of whether fans can be used in series
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As shown in the diagram, the gas flows from the branch lines into the main line. Fan 2 is an existing fan with an air volume of 10,000 and an air pressure of 10 kPa. It is now desired to add another fan at the location of Fan 1. The requirements are as follows: 1. The new fan must be able to draw air out of the pipes, with the air pressure meeting the specified requirements. 2. It must not prevent the gas from branch 2 from flowing into the main pipeline (the high pressure in the pipe between the two fans must not prevent the gas from branch 2 from being discharged). In such a case, how should the parameters of fan 1 be selected?
If fan 1 is an exhaust fan, then the pressure between fan 1 and fan 2 should not be high, right? Is it still necessary to calculate the relationship between the wind pressure in that intermediate section and the wind pressure in branch 2?
You cannot achieve this, as the ventilation cross-sectional area of the existing channel at the fan outlet is limited. The pressure at the outlet of Fan 1 restricts the pressure in Branch 2; at this point, the gas has to flow towards Branch 2 (in reverse), or the gas coming out of Branch 2 cannot merge with the flow exiting from there. Fans should be installed at the exits of Branch 1 and Branch 2, respectively, and then connected to a main duct for exhaust; moreover, a duct with an appropriate cross-sectional area (circular or rectangular) should be chosen to accommodate the flow rate from the outlets of both fans.
Fan 2 is located at the very end of the pipeline; it does not require high air pressure – as long as the air can be expelled, that’s sufficient. Therefore, the airflow volume and air pressure can be kept low
Moreover, both fans are exhaust fans; in that case, the outlet pressure of the exhaust fans shouldn’t be very high, right?
Actually, they are all called centrifugal fans; their principle is the same, and they definitely generate a large amount of force. Each fan must have one suitable for its operating conditions.
A dedicated check valve for the fan should be added to branch 2~~~
Can fan 1 be installed at the junction of branch line 1 and the main pipeline? In that case, it is sufficient to calculate the parameters of branch line 1 only. The static pressure must be lower than that of fan 2; theoretically, by connecting fans in series to increase pressure and in parallel to increase flow, the requirements can be met.
The pipelines on site cannot be moved at the moment; there is only this one reserved port. Branch 2 is located relatively close to the last fan. Is it sufficient to ensure that the pressure of the gas sent from Branch 1 to Branch 2 by Fan 1 remains at atmospheric pressure?