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Air Handling Unit Test - Air Heating Problem

  1. Aug 14, 2009 #1


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    Gold Member

    We are testing an Air Handling Unit, we need to raise the internal temperature by 30 degrees to pass the test, but cannot exceed an energy input of 500W.

    It is a completely sealed unit.

    We have four fans constantly running, consuming 384W. Firstly, how can I work out what temperature they will raise the unit to? The fan manufacturer says that all energy input becomes heat (due to it being a closed system, but please lets not debate this, just accept it for the purpose of this question and use the full 384W).

    Secondly (if part 1 doesn't raise the temperature by 30 degrees), what size heater would we need to achieve the increase?

    Box Dimensions: 1.2x1.2x3.0m
    Fan Input: 384W
    Must not exceed: 500W (but I would like some answers even if they do exceed it to show me what we would need to do to achieve the required temperature increase)

    Also, is there a way to work out how many Watts are required to raise the temperature of air by 1 degree celsius in one hour?
  2. jcsd
  3. Aug 14, 2009 #2


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    Staff: Mentor

    Nothing to debate - it's true!
    Air volume times specific heat times power = temperature rise.
  4. Aug 15, 2009 #3


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    Gold Member

    I know it's true, but I put that because with someone in work who didn't understand it I had to spend an hour explaining the concept to him and didn't fancy having to go through the same thing again.

    Thank you for this.
  5. Aug 15, 2009 #4


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    Hi, that gives me 4.23cubic metres of air, specific heat of 1.005kg/kg K and a power of 384W. Which is over 1600 when multiplied together, which is one hell of a temperature rise.

    Is the formula correct or am I making a mistake somewhere?
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