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  1. #1
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    30C to 20C in one hour?



    Hi all, greetings from Indonesia again...
    I need to calculate how much compressor power needed for this:

    I need to cool 10.000 liter (roughly 2,641 gallon) of water from 30C (86F) down to 20C (68F) within one hour.

    I found this formula:

    BTU = gallons x temperature change x 8.33

    The result for my numbers would be... 395,991 BTU or 155 HP.
    Is that number seems realistic? It seems so high, or is there a mistake?

    Thank you for all your input, really appreciate it.

    Regards,
    Yahya.



  2. #2
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    Re: 30C to 20C in one hour?

    10000l/hour = 2.8l/sec
    30deg - 20deg = 10deg
    specific heat capacity of water = 4.2

    2.8 x 10 x 4.2 = 117.6kW of refrigerating capacity.

    I don't really know what BTU's and Gallons are?

  3. #3
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    Re: 30C to 20C in one hour?

    For getting 120 kW cooling considering 10 C evaporating and 40 condensing temperature refrigeration compressor will need around 20 to 25 kW power input depending upon which refrigerant is used.

  4. #4
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    Re: 30C to 20C in one hour?

    Thank you so much for all the replies, really helps.

  5. #5
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    Re: 30C to 20C in one hour?

    Quote Originally Posted by sandybapat View Post
    For getting 120 kW cooling considering 10 C evaporating and 40 condensing temperature refrigeration compressor will need around 20 to 25 kW power input depending upon which refrigerant is used.
    May I know how did you came up with the number 20 to 25 kW power input? Thanks.

  6. #6
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    Re: 30C to 20C in one hour?

    also
    Q= MC (t2-t1)
    M=10000 Kg/ h
    C=1 for water

    Q= 10000 * 1(30-20)
    Q= 100000 cal/h

    1 Kw = 860 cal

    to get that you need to add %10 for safety and then you have to choose your Comp.

    your evaporator temp. about 10 c ( out let temp. - delta T )

    your condenser temp. about (ambient temp. + 10)

  7. #7
    Join Date
    Sep 2012
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    Re: 30C to 20C in one hour?

    As mbc has explained I tried to select compressor 120 kW capacity with 10 deg C evaporation temp and 40 deg C condensing temperature and I got the power consumed by compressor.

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