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Thread: CVHF surging

  1. #14
    Join Date
    Sep 2008
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    Delaware
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    243
    I agree that the "stall occures first. What happens next? If I tell guys my chiller is "stalling" it may not mean much. If it is "surging" I think more people will relate to that term. Undrestanding surge and its causes is the main idea.

  2. #15
    Join Date
    Jan 2008
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    windy city
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    turbo - if you don't mind, i'll be glad to have a copy

  3. #16
    Join Date
    Oct 2004
    Location
    ca
    Posts
    69

    Smile

    HI TURBOMASTER,HEY I WOULD BE INTERESTED IN READING THAT ABOUT WHAT YORK HAS TO SAY ABOUT IT.MY EMAIL IS IN MY PROFILE---THANKS PAT

  4. #17
    Join Date
    Sep 2004
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    Kansas City, Kansas, United States
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    13,833
    I too would like that?
    thanx

    st65

    hello Heavy!


    Quote Originally Posted by heavymetaldad View Post
    turbo - if you don't mind, i'll be glad to have a copy
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  5. #18
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,833
    I always liked this from Mcquay
    Centrifugal compressors differ from positive displacement compressors (such as scroll,
    reciprocating and screw). Centrifugals are aerodynamic or turbine type. They move gas by
    converting kinetic energy to pressure energy. Positive displacement compressors encase a
    quantity of refrigerant in a decreasing volume during the compression process. They provide
    excellent lift characteristics. The advantage of centrifugal compressors is their high flow
    rates capability and good efficiency characteristics.
    The simple way to understand the principle is to imagine a ball on the end of a string. One
    person swings the ball on the string. A second person is standing the second floor balcony.
    If the person swinging the ball releases ball with enough angular momentum, the ball will fly
    up to the person on the second floor balcony. The weight of the ball (molecular weight), the
    length of the string (wheel diameter) and the rotational speed (rpm) affect the angular
    momentum.
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  6. #19
    Join Date
    Dec 2008
    Location
    Dixiana, AL
    Posts
    2,611
    Rotating stall is the condition that occurs when there's not enough mass flow of refrigerant through the impeller to displace the refgt that's already in the diffuser gap, so instead of having a nice, smooth flow on into the condenser, rotating "eddies" of gas set up in the diffuser gap. A lot of folks call this "low load surge", but actually it's just a very unstable gas flow off of the impeller and through the compressor. Mass flow rate drops due to a lot of things. The most prevalent time to see this condition is when the machine unloads (vanes, not VSD), and the cooling tower is not allowed to unload with it (condenser water temp is held towards design at the same time). Stall is the condition that occurs right before surge, but if you're in a condition that will cause a full-blown surge, you have to be real quick to hear it.

    Surge is when the delta p (lift, measured in degrees) across the impeller becomes greater than the impeller can overcome, and there is a momentary reversal of gas flow through the impeller. That reversal is what creates the severe swing in current during a surge condition. Stall and surge are definitely related, but are two different things from an operational standpoint.

  7. #20
    Join Date
    Mar 2008
    Location
    philadelphia
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    373
    i wouldn't mind seeing the york info also i think my e-mail is in my profile thanks

  8. #21
    Join Date
    Sep 2007
    Location
    Somewhere in the world.
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    1,618
    Here is Yorks discription of stall detection on YK with VGD variable geometry diffuser
    Attached Images Attached Images  
    Arguing with your Boss is like wrestling with a pig in
    mud.
    After a while you realize that while you are getting
    dirty, the pig is actually enjoying it.

    It is not exactly cheating, I prefer to consider it
    creative problem solving.

    25 years ago we had Bob Hope , Steve Jobs , and Johnny Cash today we have no Hope no Jobs and no Cash !
    I can fix broke but i can't fix stupid !

  9. #22
    Join Date
    Feb 2004
    Location
    Georgia
    Posts
    374
    Ya'll got mail, hope that works OK. I'm not the brightest tool when it comes to sending stuff. My 19 year old son had to school me on the scanner.

  10. #23
    Join Date
    Feb 2004
    Location
    Georgia
    Posts
    374
    Ditaw, my email program ain't liking your email for some reason.

  11. #24
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    Jan 2008
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    windy city
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    thanks turbo. haven't had a chance to read it. worked late tonite (again)

  12. #25
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    Jan 2008
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    windy city
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    klove - great way of putting the explanation to words

  13. #26
    Join Date
    Jan 2008
    Location
    windy city
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    hey st (weed)

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