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

AI Thread Summary
To calculate the net rate of heat transfer from a person's body, the surface heat transfer coefficient must be determined for the skin, clothing, and tissue layers using the formula 1/h = 1/h(surf) + 1/h(clothes) + 1/h(tissue). The thermal conductivities for the surface tissue and clothing are provided, allowing for the calculation of their respective heat transfer coefficients (h). The temperature difference between the body and room air is 16°C, and the total surface area is 1.5 m². The user consistently arrives at a value of 127 W, while the expected answer is 130 W, indicating a potential calculation error or misunderstanding in the application of the formulas. Clarification and step-by-step guidance on the calculations are requested to resolve the discrepancy.
SunshineCat
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Homework Statement


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

Homework Equations


1/h = 1/h(surf) + 1/h(clothes) + 1/h(tissue)
h=k/d
ΔQ/Δt = hAΔT

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!
 
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I get 127.

Chet
 
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