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Homework Help: Find BTU Required for Water Cooling ?

  1. Aug 24, 2016 #1
    1. The problem statement, all variables and given/known data

    Calculate the BTU/hr required for water to lower its temperature to find the compressor capacity required

    - Cool 30 Liters of water from 50 degree Celsius(T1) to 25 Degree Celsius(T2) – ( 122 to 77 Fahrenheit )
    -Water in a closed vessel, Static, not flowing.
    -Max Time Available to cool the water - 10 to 15 mins (not sure if time is relevant for finding the BTU, But it will be ideal to find the compressor which can do the job in the above time)

    2. Relevant equations

    Specific heat equation
    Heat added = specific heat x mass x (tfinal - tinitial)

    3. The attempt at a solution

    Specific heat of water = 4.184
    Mass = 30 litres = 30,000 grams(approx)
    Tfinal - Tinitial = 25 Degree C

    bit confused with the units used so I guess I am getting wrong answer
    Kindly help to fix this

  2. jcsd
  3. Aug 24, 2016 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Google "British thermal unit."
  4. Aug 24, 2016 #3
    1 liter = 1kg = 2.205 lbm

    1 C = 1.8 F

    Heat capacity of water = ##1 \frac{BTU}{lbm\ F}##
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