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Determine the thermal effieincy of a heat transfer process

  1. May 28, 2012 #1
    1. The problem statement, all variables and given/known data
    determine the thermal effieincy of a heat transfer process where the following data has been used
    Input=3kW
    1.7 litres of water have been heated from 313K to 375K in 2.5 minutes
    specific heat capacity of water= 4.19kj/kgK

    2. Relevant equations
    Thermal efficiency= network done (W)
    total heat supplied (Q)
    



    3. The attempt at a solution
    am struggling where to start only done simple tasks
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 28, 2012 #2

    rock.freak667

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    Homework Helper

    Well you have 1.7 L of water being heated from 313 K to 375 K. So how much heat does this require? (look at the units of specific heat capacity). This will be your work done W.

    In order to convert this to Watts, you will need to use the formula Power = work done/time.
     
  4. May 29, 2012 #3
    output=1.7*4.19*(375-313)/(2.5*60)=2.914473Kw. 2.9174473/3= 0.981 or 98.1%. Thanks alot for help could you confirm this
     
  5. May 29, 2012 #4

    rock.freak667

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    Homework Helper

    That should be correct.
     
  6. May 29, 2012 #5
    thanks
     
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