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  1. #1
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    Air flow and cooling capacity



    Does cooling capacity increase with increased air flow?
    Last edited by jamo1989; 17-12-2014 at 06:49 PM.



  2. #2
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    Re: Air flow and cooling capacity

    Short answer is no.

  3. #3
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    Re: Air flow and cooling capacity

    Hi, room sensible heat = 1.08 x cfm x delta t.
    So if all parameters are kept constant then increase in cfm will increase the cooling capacity.
    Vijay Kumar
    HVAC Design Engineer

    BMCPL

    "The more you sweat in peace less you bleed in war"

  4. #4
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    Re: Air flow and cooling capacity

    Sorry Vijay,

    If the energy input and efficiency is constant wouldn't the delta T change depending on airflow?


  5. #5
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    Re: Air flow and cooling capacity

    Hi,

    Rsh = 1.08 x 1000 cfm x 10 delta t
    Rsh = 10800Btu/he

    Rsh = 1.08 x 2000cfm x 10 delta t
    Rsh = 21600 But/hr.

    So if we increase cfm, cooling capacity increases.

    Vijay
    Vijay Kumar
    HVAC Design Engineer

    BMCPL

    "The more you sweat in peace less you bleed in war"

  6. #6
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    Re: Air flow and cooling capacity

    OK,
    But what if you only got a 10800Btu unit feeding the indoor coil?

    Similary, what happens to the delta T if you got 21600 Btu unit feeding a 10800 Btu coil?

    Surely the delta T can't be seen as a constant???


  7. #7
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    Re: Air flow and cooling capacity

    Quote Originally Posted by vijay_study View Post
    Hi,

    Rsh = 1.08 x 1000 cfm x 10 delta t
    Rsh = 10800Btu/he

    Rsh = 1.08 x 2000cfm x 10 delta t
    Rsh = 21600 But/hr.

    So if we increase cfm, cooling capacity increases.

    Vijay
    Not a chance. Dt changes and cooling capacity remains the same.
    If you were right with your assumption, you could have cool a 10m by 10m cold room only by increasing air flow with a 1 btu unit output.
    Please go back to the drawing board and try again.

  8. #8
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    Re: Air flow and cooling capacity

    Oh Chemi,

    You never let me have any fun...

  9. #9
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    Re: Air flow and cooling capacity

    Hi, the question here is that, does the cooling capacity increase with an increase in airflow. My point here is that if I supply 1000cfm of air I can remove 10800 But/hr of heat if room temperature is 74degF and supply air temperature is 64degF.

    Similarly if I increase the supply cfm to 2000cfm having supply air temperature of 64degF then I can remove 21600Btu/hr of heat if room temperature is 74deg F.

    Vijay
    Vijay Kumar
    HVAC Design Engineer

    BMCPL

    "The more you sweat in peace less you bleed in war"

  10. #10
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    Re: Air flow and cooling capacity

    Does a 18k btu rated split give the full 18k btu's of cooling on lo, med and hi or just hi?

  11. #11
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    Re: Air flow and cooling capacity

    Quote Originally Posted by The Viking View Post
    Oh Chemi,

    You never let me have any fun...
    Isn't fun depends on airflow?

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