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How is a psychrometric chart for other than sea level atmospheric pressure generated?

  1. Oct 4, 2009 #1
    Sorry, no thermo reference handy to try and figure it out myself. It would be nice to know, in case our company does any work up on the mountain (on a new telescope project coming up).
     
  2. jcsd
  3. Oct 12, 2009 #2
    Re: How is a psychrometric chart for other than sea level atmospheric pressure genera

    Well, the psychrometric chart is generated from experimental data, but I'm sure you could determine gas-vapor properties for air at a different pressure using the fundamentals and your thermodynamics text. However I believe ASHRAE publishes charts for a variety of elevations and you can order one through them. My HVAC design prof mentioned having to get one for his work in our state of Colorado. Hope that helps some.
     
  4. Oct 12, 2009 #3

    Mech_Engineer

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    Re: How is a psychrometric chart for other than sea level atmospheric pressure genera

    Air density and water vapor pressure play a primary role in the layout of the psychrometric chart, so when going up in altitude they must be accounted for. There are manual calculations available that enable you to calculate the values, or you can just look up a psychrometric chart at or near the altitude you're looking for.

    For example, my work is at 7000ft above sea level. As such, I have used a psychrometric chart for that altitude in the past. Similar to this one: http://www.luhow.com/client/coolerado.com/CoolTools/Psychrmtrcs/7500PsychrmtrcLetter.pdf" [Broken]

    There are also several calculation software packages available that have psychrometric calulcation abilities, and I assume they can compensate for altitude changes.
     
    Last edited by a moderator: May 4, 2017
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