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Thermodynamics Heat Engine

  1. Feb 11, 2014 #1
    1. The problem statement, all variables and given/known data
    A haet engine works based on the difference of the temperature at the top and bottom of the ocean. The machine is solar powered and the average solar irradiance is 240W/m^2 and the temperature at the surface of the water is 25ºC. Calculate the temperature at the bottom of the ocean so that the machine debits a power of 0.1MW to a surface area of 10^4 m^2.

    2. Relevant equations
    Q=σ*A*T^4(surface)


    3. The attempt at a solution
    I am stuck in this one... I don't know if it is possible for you to give me some hint. I'm not sure if I need to find the efficiency here, but I'll probably will need it to get the heat at the bottom and maybe trough there get the temperature.
     
  2. jcsd
  3. Feb 11, 2014 #2

    jim hardy

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    Science Advisor
    Gold Member
    2016 Award

    is sure a roundabout way to phrase what i take to be power balance....

    Do you suppose he means "delivers useful work of 10 watts/m2 at Carnot efficiency?

    If so, it seems to me he's given you both efficiency and Thot .
     
  4. Feb 11, 2014 #3

    Borek

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    Staff: Mentor

    My bet is that is about efficiency only - you are given energy input and energy output. See if you can follow from here.

    Edit: Jim was slightly faster, and we definitely said the same thing.
     
  5. Feb 11, 2014 #4
    First I want to thank you both for the answer. Yes, I concluded that it was supposed to use the efficiency and I was given Th being Tc the temperature at the bottom. It's done!
     
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