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  1. #1
    Join Date
    Jul 2018
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    Texas
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    1 2 and 3 Pass Chillers?

    Hello,
    I am new to HVAC-Central Plant Operations.Still trying to learn as much as I can.

    Can someone please explain why (In layman's terms) Chiller evaporators are either 1 2 and 3 pass? Why the difference? Is their a benefit to more passes?

    Any help would be much appreciated!
    Thank you

  2. #2
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    the lower the number of passes, the less water pressure drop there is. generally, the fewer the number of passes, the higher the allowed water flow rate is.

    the higher the number of water passes, the greater the heat transfer efficiency.

    as with most things, there is a balance that needs to be struck between heat transfer efficiency, flow rate and cost of pump operation.
    Don't step on my favorite part of the Constitution just to point out your favorite part.

    Political Correctness is forced on you because you have forgotten decency.

    Technically speaking, they are all heat pumps.

  3. Likes manny238 liked this post
  4. #3
    Join Date
    Feb 2004
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    Kentucky
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    post an email address and you will learn more!

  5. #4
    Join Date
    Jul 2007
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    Quote Originally Posted by mathias View Post
    post an email address and you will learn more!
    If he does that he will be breaking the forum rules.

  6. #5
    Join Date
    May 2012
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    Some general info:
    (If you have an overview of your specific central plant maybe we could provide some more specific info. Constant Flow, Variable Primary, Chiller Type, Configuration, Etc.):

    Typically it is beneficial for a variable evaporator flow central plant to have chiller(s) capable of handling an evaporator water flow 50% of the design flow. This extends the chillers ability to operate at low loads without bypassing flow (wasted energy).

    There is a lot that goes into central plant design, but in laymen's terms the more passes a chiller has the lower the minimum flow limit is. At the same time more passes equate to increased pressure drop and pumping power.

    In my opinion; the majority of applications water-cooled chiller evaporators have Two Passes. Single pass chillers are the least common design.

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