Heat and Mass Transfer - finding surface temp

AI Thread Summary
The discussion focuses on calculating the surface temperature (Ts) of a wire conducting electricity, given specific parameters such as resistance, diameter, and heat transfer coefficients. The user attempts to derive Ts using heat transfer equations but encounters unreasonably high temperature values when substituting current values. Suggestions include solving the equation numerically and analyzing the magnitudes of convective versus radiative heat transfer to determine which is more significant. The approach of breaking the equation into two separate equations is questioned, as it may not logically apply in this context. Overall, the conversation emphasizes the complexities of heat transfer calculations in electrical systems.
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Homework Statement


A wire is conducting electricity, given values of :

R' = .4 ohms/m D = .002 m Tinf=300k Tsur=300k k=380W/m*C

emissivity = 1 h=10W/m^2*C Ts = Find this sigma=Stefan boltzmann

Plot the Temperature of the wire versus the current I for 0<I<10 amps.


Homework Equations



P = I^2*R' = q'

Convective heat = h(Ts-Tinf) + sigma(Ts^4-Tsur^4) = I^2*R' / pi*D = q'/pi*D = q''

The Attempt at a Solution



Ok So my attempt as essentially to break down the equation I have set to convective heat. After breaking things up and solving for Ts, I found :

"(I^2*R' / pi*D) + (h*Tinf) + (sigma*(Tsur)^4)" = Ts(h+sigma*(Ts)^3)

**Ill use " ... " for the left hand side of the equation

So my attempt was to break into into two equations:

"..." = Ts and Ts = Cubed Root ( ("..." - h)/sigma)

For some reason whenever I go to solve for Ts, I get pretty absurd numbers.

Using Kelvin I get 3932 K for I=0
I don't even think I can use celsius here because of the stefan boltzman constant (My equations are not temperature differences).

Where am I going wrong and is this approach even possible?
 
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Where are you getting the approach of "break[ing it] into...two equations"? Like if A = BC, then A = B and A = C? That doesn't make sense to me.

How about solving the equation numerically, or calculating the magnitudes of the convective and radiative heat transfer and seeing if one dominates over the other?
 
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