Heat Transfer - Conduction and Radiation

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Homework Statement


An animal has a core body temperature of 37oC and a skin temperature of 34oC while in surrounding of an air temperature of 25oC. If the skin temperature fell, what would happen to:
(i) the rate of heat transfer via conduction through body tissue?
(ii) the rate of heat loss via radiation


Homework Equations



Q = h * A * [change in temp]

Qnet = e * (boltzsman) * (Tsurface4 - Tenvironment4)

The Attempt at a Solution



(i) the rate of transfer due to conduction will increase because the change in temperature has increased. e.g. (37 - 30) > (37 -34)

(ii) the rate of transfer due to radiation will decrease because the Tsurface4 has decreased.

Whilst my solution seems ok, doesn't the heat transfer need to be conserved?

ie. my textbook says the following:
" Heat must be transferred away from the outer surface at the same rate as it arrives there"

So I take this to mean, if one increases the other must increase and vice versa, If one decreases, the other must decrease.

With my solution, I have conduction increasing but radiation decreasing...
 
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Answers and Replies

  • #2
Mapes
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Solution looks good to me. And I agree with your argument about energy conservation; in fact, that's why skin temperature is maintained at an equilibrium level that remains stable unless one of the other parameters changes also.
 

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