If the Fan's Air Flow is Doubled, Does That Mean the Cooling Effect is Doubled as Well?

Teach Me Please! Ms. Ori
Teach Me Please! Ms. Ori
  • Mr. Vex

    I wonder if using 2 fans would double the air flow...?

  • Ms. Ori

    What is it, Vex? Staring at the materials.

Ms. Ori and Mr. Vex
  • Mr. Vex

    Ms. Ori. Actually, a customer asked me about axial flow fans. They want another fan installation because the cooling effect is not enough, but they want to know how the characteristics will change.

  • Ms. Ori

    Oh, and what did you say?

  • Mr. Vex

    I thought that putting 2 fans together would double the air flow. If the air flow is doubled, then the cooling effect is also doubled? Right?

  • Ms. Ori

    Yes, if you install 2 of them side by side, you will approximately double the maximum air flow. But even doubling the maximum air flow will not simply double the cooling effect. It depends on the conditions inside the enclosure to be cooled.

  • Mr. Vex

    Really?

  • Ms. Ori

    There was something important when considering the characteristics of fans. Do you remember what "pressure loss" is?

  • Mr. Vex

    It stands for "wind resistance," right?

  • Ms. Ori

    That's right. When sending air inside an enclosure, if the devices inside the enclosure are clustered together, the resistance increases, and it becomes difficult for the air to flow. In this case, static pressure, which is the force that pushes (or pulls) air into the enclosure, is important. In other words, in order to get a sufficient cooling effect, you have to choose a fan that can provide static pressure that exceeds the pressure loss inside the enclosure.

  • Mr. Vex

    I see. You have to choose a fan by considering not only air flow but also pressure loss.

  • Ms. Ori

    That’s right. The figure below is a typical characteristics diagram of a fan. For example, let's say the required air flow is Q1, and the pressure loss inside the enclosure is P1. So, for this fan, the static pressure value is P2, which is higher than the required static pressure, P1. This means that you can get enough air flow.

    Air flow and static pressure characteristics
    Air flow and static pressure characteristics

    With that in mind, let's look at the differences in characteristics depending on how the fans are arranged.
    First of all, if the space is large and the pressure loss is low, multi-fan control, which can increase the air flow, is more suitable.

    When pressure loss is low

    • Parallel
      Parallel

      Installation Method for 2 Parallel Fans

    • Relationship Between Air Flow-Static Pressure Characteristic Curve and Pressure Loss
      Relationship Between Air Flow-Static Pressure Characteristic Curve and Pressure Loss

    And if the devices in the equipment are clustered together and the pressure loss is high, series operation, which increases static pressure, is the best choice.
    If you want to increase the static pressure even more, a push-pull method, which allows wind flow from the intake to the exhaust outlet, is also effective.

    When pressure loss is high

    • Series
      Series

      How to install 2 fans in series
      -

    • Push-pull
      Push-pull

      Fan on intake side and exhaust side
      How to install

    • Relationship Between Air Flow-Static Pressure Characteristic Curve and Pressure Loss
      Relationship Between Air Flow-Static Pressure Characteristic Curve and Pressure Loss
  • Mr. Vex

    I see! I’ll explain this to the customer as soon as possible! Also, a type like the MRS Series, with its high air flow and static pressure, can provide a significant cooling effect from the start. I'll introduce that as well.

  • Ms. Ori

    You've come a long way! Good for you! Good luck introducing the products.

  • February 19, 2018  Updated with the latest information.

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