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Homework Help: Heat transfer from body through layers, using h, T, d, A

  1. Apr 6, 2015 #1
    1. The problem statement, all variables and given/known data
    Consider a person in a room with an air temperature of 21C. The persons core body temperature is 37C and their surface tissue thickness is 5 mm. If the total surface area of their skin is 1.5 m2, and they are wearing clothes of a thickness of 2 mm and the surface heat transfer coefficient (including conduction and radiation) is hsurf = 8.1 W m−2 K−1 then what is the net rate of heat tranfer from this persons body (in W)

    thermal conductivity of surface tissue: kst = 0.2 W m−1 K−1
    thermal conductivity of clothing: kclo = 0.05 W m−1 K−1

    2. Relevant equations
    1/h = 1/h(surf) + 1/h(clothes) + 1/h(tissue)
    ΔQ/Δt = hAΔT

    3. The attempt at a solution
    I think you need to find the h for surface, tissue and clothes, and combine using 1/h = 1/h(surf) + 1/h(clothes) + 1/h(tissue)
    We can find h for clothes and tissue using h=k/d ???
    Then can use ΔQ/Δt = hAΔT using the new h value, surface area (1.5) and temp difference (37-21=16)
    But I keep getting 103 instead of 130 as the answer says
    Can someone work it out and explain the working? Thanks in advance!
  2. jcsd
  3. Apr 6, 2015 #2
    I get 127.

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