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Homework Help: Heat loss by Conductance

  1. Jan 26, 2010 #1
    1. The problem statement, all variables and given/known data
    A man of 75 kg (1.77 m^2 surface area) in weight, dressed in appropriate winter clothing stands on a winter pond. The temperature outside is -5 degrees Celsius. Assume that the surface layer of his skin is 5 mm thicker and is not perfused with blood (behaves as an insulating layer). The temperature of blood in the vasculature just below this layer is 20 degree. Compute the thickness of air layer that needs to be trapped in the clothing such that heat loss by conduction is 100 W/m^2.

    My only problem is the equation. I cannot figure out what to use. The class has no textbook and the lecture slides have the equation. I think I missed an equation when taking notes. I asked the prof but not reply yet. Any information is key! What is throwing me off is the skin layer.

    2. Relevant equations

    I do have one equation and its Watts/Area = k(T1 - T2) / d

    T1 and T2 are temperatures of the skin and ambient area, respectively.
    d is the distance from skin to the ambient temperature outside.
    k is the conductance constant

    No info is given about the jacket's material etc. The question is stated above.
  2. jcsd
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