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Thread: Multiple fans

  1. #1
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    Multiple fans



    Hi Guys

    I am pretty new to this, and I am in an process in which I have to design an complete aircon unit.
    In regard to this, I was wondering how you read static pressure drop when you use multiple fans, ex. 2 fans with the following fan performance curve.

    Fan.PNG

    Best regards
    Michell



  2. #2
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    Re: Multiple fans

    By the way, it should be the same type of fan as well, ex. 2x B60 or 2xB70

  3. #3
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    Re: Multiple fans

    I assume you propose to operate these two fans in parallel, the first thing to understand is that the external pressure the equipment will operate against is pretty much set at the design stage ( I am assuming this system is to be connected to ductwork).
    With the anticipated external system resistance established by the configuration of the distribution system the only parameter that will change will be the air volume delivered by the fan.
    Two fans in parallel running at the same speed and connected to the same distribution system will operate as if they were one fan so read the fan curve as for one fan but compensate for the air volume via each fan.
    Refer to standard fan laws. Google "Woods Guide to Fan Engineering" look at page 138
    Location, United Kingdom

  4. #4
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    Re: Multiple fans

    Actually it is not to be connected to ductwork, it is for telecom cooling, and it just have to connect to a cabinet where it has to cool what is inside.
    What about the pressure static pressure, will the two fans be be supplementing each other or will they just be as if they where 1 fan?
    The problem is that I need to use the aircon for, as mentioned earlier, telecom cooling and I havent got much space, so meet the volumeflow demand I need to use two 92x92 fans and then I am unsure if they will be able to meet the other demand which is that there need to be an pressure drop between return air and supply air.

    Best regards
    Michell

  5. #5
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    Re: Multiple fans

    an pressure drop of 30 Pa !

  6. #6
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    Re: Multiple fans

    Let us have the details of the cabinet, if the air is to be supplied into the cabinet and returned to the cooling coil via the cabinet then to establish an estimate of the external resistance that the fans will operate against then this will in effect be just like a duct.
    I am sure one could make some assumptions regarding the resistance, it will not be accurate however.
    The best solution to your problem is to make an estimate of the resistance oversize the fans and provide some form of speed regulation to allow fine tuning of the the system post installation.
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