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Electric cable in a Vertical Tube: Estimate the Conductor Temperature

  1. Sep 9, 2010 #1

    I have an electric cable in a vertical steel Tube. I estimated the temperature that will reach the JTube exposed to sun radiation.

    I came with these equations

    QCable+ Qsun - Qradiated = mc( Tfinal - TAmbient)

    where QRadiated= k.A.(Tfinal^4-TAmbient^4), QSun=234 [W/m^2] * A
    A=Area of the Tube
    K=Radiation constant= 4E-8
    m=Mass of the tube
    c=473 for steel

    I finally find for a day the maximum Temp that will reach the Tube ( Resolved a quartic Equation with Tfinal as an unknown knowing that Tambient=34 for instance )

    However I want to know what temperature will reach the conductor ( after a day =86400 Secs)

    What I thought was

    For each t ( from 0 to 86400 secs)

    QCable = mc( Tfinal - TAmbient) - Qsun + Qradiated

    For each t, I know the right side. I Find QCable and then Divide it by the Thermal Mass to find the Temperature :/

    However I find extremely large Results so I think it might be wrong ( it shouldnt be bigger that 90 Degrees)

    Hope someone will be able to help me because I am really losing Hope...

    Thank you very much Guys

  2. jcsd
  3. Sep 10, 2010 #2
    Ooooooook I found it :)
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