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Heat transfer - generator losses and dissipation

  1. Jul 22, 2011 #1
    I am currently working on a small personal project.

    It is a small under-water generator/ motor so the setup is as follows. The generator and gearbox are mounted on steel struts within an air-tight nacelle of sorts which is cylindrical and made of steel. The nacelle is submerged in cold water which will be flowing past. I am trying to calculate the heat within the nacelle and what natural cooling will occur knowing only material properties, dimensions and generator and gearbox losses. I am struggling to generally work out how to go forward and work out the temperatures over time. Any help would be great.
  2. jcsd
  3. Jul 22, 2011 #2
    Your heat loss from the surface of the nacelle is:

    q loss = h A (Ts - Twater)

    q loss = heat loss
    h = convenctive heat transfer coefficient (more on this below)
    A = surface area of nacelle
    Ts = temperature on surface of nacelle
    Twater = average water temperature

    Try figuring h from a natural circulation correlation for a vertical cylinder. You can attack this with the Chruchhill and Chu, LeFevre and Ede, or Yovanovish correlation.

    If you figure your q-loss from gearbox data, you find find out how hot your nacell will get by figuring Ts.
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