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  1. #1
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    Jul 2009
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    new york
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    what is the water temperature through a cooling tower expected to be

    Is it suppose to increase by 20 or decrease by 20 degrees

  2. #2
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
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    1,090
    Hmmm.... Cooling tower....

    Wonder what that could mean?

  3. #3
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    Quote Originally Posted by syndicated View Post
    Hmmm.... Cooling tower....

    Wonder what that could mean?
    I don't do cooling towers. If you don't know cool

  4. #4
    Join Date
    Jan 2011
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    1,114
    decrease. The delta T will vary depending on environmental conditions.

  5. #5
    Depending on the ambient conditions.

  6. #6
    Join Date
    Mar 2011
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    Malaysia
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    Well it all depends on the ambient wetbulb and your entering temperature.

    In the tropics - where I am located - it always decreases (in temperate,, say winter - it should also decrease as the wetbulb will be lower than summer period). The decrease depends on the ambient wetbulb. I will use the crossflow cooling tower as an example... water enters the cooling tower at the top which is called the hot basin (reminder: I am in the tropics). Air is forced upwards by the rotating fan. both air and water interact and the air picks up the heat from the water through forced evaporation. The forced evaporation cools the water as it falls through the infill. But the final water temperature at the cold basin (at the bottom of the cooling tower) is limited by the ambient wetbulb. Wetbulb is basically the temperature of the air that is already saturated with water. Imagine a closed box and you have a nozzle that sprays fine particles of water inside the box..everything is sealed. The air in the box absorbs all fine water mist until it cannot hold anymore water - it begins to rain inside the box! - the temperature at point when the air is "full" (just before it starts raining) is called the wetbulb.

    Usually for good heat transfer rate (but with standard losses) we expect the final (cold basin) water temperature to be 2.2 to 2.5 Deg C above the ambient wetbulb. if the cooling tower was in a perfectly adiabatic room, the final temperature will be equal to the wetbulb. The difference between the water temperature at the cold basin and the ambient is called approach temperature.

    So the answer to your question : Ideally it should be as close as the wetbulb. Practically about 2.2 to 2.5 Deg C + ambient wetbulb is good. Higher approach temperature could mean messed up infills, bad airflow, undersized cooling tower.....

    Hope the above helps.. and I don't mind being corrected if I am wrong

  7. #7
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    Jul 2009
    Location
    new york
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    599
    Standard was 20 at a min

  8. #8
    Join Date
    May 2010
    Location
    TO, Canada
    Posts
    104
    Quote Originally Posted by HVAC_MY View Post
    Well it all depends on the ambient wetbulb and your entering temperature.

    In the tropics - where I am located - it always decreases (in temperate,, say winter - it should also decrease as the wetbulb will be lower than summer period). The decrease depends on the ambient wetbulb. I will use the crossflow cooling tower as an example... water enters the cooling tower at the top which is called the hot basin (reminder: I am in the tropics). Air is forced upwards by the rotating fan. both air and water interact and the air picks up the heat from the water through forced evaporation. The forced evaporation cools the water as it falls through the infill. But the final water temperature at the cold basin (at the bottom of the cooling tower) is limited by the ambient wetbulb. Wetbulb is basically the temperature of the air that is already saturated with water. Imagine a closed box and you have a nozzle that sprays fine particles of water inside the box..everything is sealed. The air in the box absorbs all fine water mist until it cannot hold anymore water - it begins to rain inside the box! - the temperature at point when the air is "full" (just before it starts raining) is called the wetbulb.

    Usually for good heat transfer rate (but with standard losses) we expect the final (cold basin) water temperature to be 2.2 to 2.5 Deg C above the ambient wetbulb. if the cooling tower was in a perfectly adiabatic room, the final temperature will be equal to the wetbulb. The difference between the water temperature at the cold basin and the ambient is called approach temperature.

    So the answer to your question : Ideally it should be as close as the wetbulb. Practically about 2.2 to 2.5 Deg C + ambient wetbulb is good. Higher approach temperature could mean messed up infills, bad airflow, undersized cooling tower.....

    Hope the above helps.. and I don't mind being corrected if I am wrong
    Excellent explanation my friend!

  9. #9
    Join Date
    Mar 2011
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    Malaysia
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    Quote Originally Posted by rupa104 View Post
    Excellent explanation my friend!
    Thank you

  10. #10
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    May 2013
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    near knoxville tenessee
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    168
    that was a hell of a reply to such a simple question. You a teacher? Teachers have all the patience. I have none.

  11. #11
    Join Date
    Mar 2011
    Location
    Malaysia
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    Quote Originally Posted by johnqpublic View Post
    that was a hell of a reply to such a simple question. You a teacher? Teachers have all the patience. I have none.
    I am consultant / contractor on ACMV (HVAC) and compressed air systems. All my jobs are performance based - no savings or performance as promised (sometimes its humidity control for example and not energy), I dont get paid until it is achieved. Hence the need to be precise with my terms and conditions and what i can and cannot achieve - and yes, I do teach in technical workshops

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