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Heat transfer problem

  1. Sep 22, 2016 #1
    1. The problem statement, all variables and given/known data
    a copper pot's radius is 12 cm, the thickness is 5 mm. It is placed on the stove for boiling, if the temperature of the stove is 115 oC while the water is 100 oC. How much of water that evaporates per minute

    2. Relevant equations
    ΔQ/Δt = (A)(k)(ΔT) / (L)
    Q=mcΔT

    3. The attempt at a solution

    I 've calculated the rate of heat transferring in a minute with the first equation and I got the amount of the heat to calculate mass later with the second equation. Does my process correct?
     
  2. jcsd
  3. Sep 22, 2016 #2

    kuruman

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    The method for calculating the heat per minute going in is correct. You need to rethink the second equation. The water is already at the boiling point so any heat that goes in it cannot raise its temperature. What does it do instead?
     
  4. Sep 22, 2016 #3
    it is changed into gas - steam? I know that when then heat reach the phase change, the temperature won't change anymore. How can I apply this with the second equation? Does the change in temperature still the same at 100oC because if there is no change in the temperature the whole equation will broke down (divided by 0)
     
  5. Sep 22, 2016 #4

    kuruman

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    You should not be looking at Q=mcΔT. What equation is applicable when you have a phase transition?
     
  6. Sep 9, 2017 #5
    In evaporation all energy absorbed is going to be latent and not sensible. Use this equation q=hfg [J/kg]. hfg represents the enthalpy of evaporation, this means, the specific energy required to go from one side of the dome(saturated liq) to the other side of the dome (saturated steam).
     
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