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  1. #1
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    How calculate AHU performance?



    How can I manually from the known values of Return or Supply Air Volume, Return Air Supply Air readings and Readings
    calculate "AHU Performance Calculated "values (Total kW, kW Sensible, Latent kW, SHR, Condensate l / hr)

    As a here fridgetech.com/calculators/ahucalc.html

    Beginner in the world of air conditioners. Thank you all for your help.



  2. #2
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    Re: How calculate AHU performance?

    if you have flash player, they have some simulators to play whit.

    have fun,
    http://www.techno-froid.com http://www.techno-froid.com/index.ph...d=31&Itemid=32

    Ice
    Last edited by icecube51; 26-08-2010 at 01:38 PM.

  3. #3
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    Re: How calculate AHU performance?

    Thanks for your help, the best simulation yet on this topic. But how to calculate without a computer, only numbers, graphs, paper and pencil?

  4. #4
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    Re: How calculate AHU performance?

    yep, just like in the good old days.

    Ice

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    Re: How calculate AHU performance?

    Every air conditioning unit is different, and has unique values of output for the inputs you list. You therefore need to go to a manufacturer’s web site – Carrier, Trane, and York among others give free access to their performance data. Given a particular size and type of unit, say 5 ton, split air cooled air conditioner (as opposed to heat pump) you use the manufacturer’s performance tables to look up the total and sensible capacities, and total input KW.

    My book HVAC From Clean Sheet to Blueprint – A Mechanical Designer’s Guide to Design of Small Commercial and Institutional HVAC Systems describes how to use this data to select the air conditioner that matches your loads, and how to plot the data on a psychrometric chart. Once this is done, you can read the difference in specific humidity off the chart at the coil inlet and leaving conditions and compute the condensate removal rate.

    My book is currently available for free download at my HVAC design web site www.nettally.com/doughert.
    Last edited by dougheret0; 30-08-2010 at 04:54 PM. Reason: repair formatting

  6. #6
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    Re: How calculate AHU performance?

    Quote Originally Posted by jjosip View Post
    How can I manually from the known values of Return or Supply Air Volume, Return Air Supply Air readings and Readings
    calculate "AHU Performance Calculated "values (Total kW, kW Sensible, Latent kW, SHR, Condensate l / hr)

    As a here fridgetech.com/calculators/ahucalc.html

    Beginner in the world of air conditioners. Thank you all for your help.
    Measure the AHU inlet volumetric flow rate.
    Air inlet temperature and humidity
    Air outlet temperature and humidity
    Find out the barometric pressure.
    Using inlet temperature and barometric pressure calculate air density (kg/m^3).
    Multiply density by vol flow rate to get mass flow.
    Sensible (kW) duty is mass flow (kg/s) x temperature difference (K) x 1.006
    For latent, plot the inlet and outlet air conditions on a psychrometric chart and read the change in water content inlet to outlet (kg/kg), multiply this by air mass flow to get condensate rate (kg/s). To convert this to a latent duty you can read it from the psych chart or just multiply condensation rate by the latent heat of vaporisation (4.2 KJ/KgK)

  7. #7
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    Re: How calculate AHU performance?

    Quote Originally Posted by Rich_J View Post
    Measure the AHU inlet volumetric flow rate.
    Air inlet temperature and humidity
    Air outlet temperature and humidity
    Find out the barometric pressure.
    Using inlet temperature and barometric pressure calculate air density (kg/m^3).
    Multiply density by vol flow rate to get mass flow.
    Sensible (kW) duty is mass flow (kg/s) x temperature difference (K) x 1.006
    For latent, plot the inlet and outlet air conditions on a psychrometric chart and read the change in water content inlet to outlet (kg/kg), multiply this by air mass flow to get condensate rate (kg/s). To convert this to a latent duty you can read it from the psych chart or just multiply condensation rate by the latent heat of vaporisation (4.2 KJ/KgK)
    Sorry, slight slip, 4.2 should be 2250KJ/KgK

    Is ther an edit function?

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    Re: How calculate AHU performance?

    One of the Mods with Priviledges for the section can edit it for you.( Andy, Peter_1, Mark, chillin out, Brian_UK, WebRam )


    When you post a reply you normally get 15 minutes to carry out any editing - although since the forum upgrade this may have changed.
    Last edited by frank; 06-09-2010 at 08:05 PM.
    I'm back on the Pale

  9. #9
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    Re: How calculate AHU performance?


  10. #10
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    Re: How calculate AHU performance?

    really valuable animations

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