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Thread: DOAS issue

  1. #1
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    Question DOAS issue



    we have failures in some application engineering in DOAS application. The system is consisted of metal cooling panel(manufactured by our own) and DOAS unit. The cooling panel occur condensate in the hottest days in summer. our boss said the DOAS unit is without enough dehumidifying capacity. i think there maybe the possibility as follows:
    # cooling panel actual capacity is low than designed value
    # the hottest days beyond the design consideration
    # system match is not good
    # control method cannot prevent the condensate happen

    i'm new in this field ,pls advice.
    thx



  2. #2
    shogun7's Avatar
    shogun7 Guest

    Re: DOAS issue

    Quote Originally Posted by lc_shi
    we have failures in some application engineering in DOAS application. The system is consisted of metal cooling panel(manufactured by our own) and DOAS unit. The cooling panel occur condensate in the hottest days in summer. our boss said the DOAS unit is without enough dehumidifying capacity. i think there maybe the possibility as follows:
    # cooling panel actual capacity is low than designed value
    # the hottest days beyond the design consideration
    # system match is not good
    # control method cannot prevent the condensate happen

    i'm new in this field ,pls advice.
    thx
    Condensation can only occur if you go below the dew point of atmosphere you are working with( it is the temperature below which water vapor in the air will start to condense and it is also 100%humidity point) and the hotter the air the higher the dew point will be because the hot air can hold more moisture then cold air. If you know the dry bulb and the wet bulb you can determine, with a psychrometric chart, the relitave humidity, the dew point and many other psychrometric properties of air. If you only want to remove sensible heat then you must keep the panel temperature above the dew point of the surrounding atmosphere.

  3. #3
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    Re: DOAS issue

    What is a DOAS unit?
    After editing I found via Google: Dedicated Outdoor Air System.
    So an air handling unit? Am I correct?

    In that case, are the metal cooling panels in the ceiling, a ceiling cooling with tubes mounted on it, mounted horizontally?

    Have a look here then, great paper I got on my computer and it's still working.
    http://www.zent-frenger.de/download/...ng_systems.pdf

    and also
    http://www.personal.psu.edu/users/j/...is_2003_AJ.pdf
    Last edited by Peter_1; 28-12-2004 at 08:35 AM.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  4. #4
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    Re: DOAS issue

    thanks for your help.

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