Heat Transfer: Heat from junction box to surface

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SUMMARY

The discussion focuses on calculating the surface temperature of a stainless steel junction box in a 35°C ambient environment, which contains electrical boxes generating 30W of heat. The relevant equations include heat transfer by convection and radiation, specifically Q_dot_total = Q_dot_conv + Q_dot_rad, Q_dot_conv = hA(Ts-T∞), and Q_rad = εσ(Ts^4 - Tsurr^4). The user encountered a 4th order equation when solving for Ts, resulting in unreasonably high temperatures, indicating potential arithmetic or conceptual errors in their calculations.

PREREQUISITES
  • Understanding of heat transfer principles, specifically convection and radiation.
  • Familiarity with the equations of heat transfer, including Q_dot equations.
  • Proficiency in solving polynomial equations, particularly 4th order equations.
  • Knowledge of thermal properties of materials, such as emissivity and thermal conductivity.
NEXT STEPS
  • Review the derivation and application of the heat transfer equations Q_dot_conv and Q_dot_rad.
  • Learn how to calculate the heat transfer coefficient (h) for different surfaces.
  • Explore methods for solving higher-order polynomial equations effectively.
  • Investigate the thermal properties of stainless steel and its impact on heat dissipation.
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Students and professionals in mechanical engineering, thermal management specialists, and anyone involved in heat transfer analysis and thermal system design.

Paosy27
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Homework Statement


Calculate the surface temperature of a stainless steel junction box that is in a 35C ambient temperature environment. There are electrical "boxes" that generate 30W of heat inside of this box.


Homework Equations


(1) Q_dot_total = Q_dot_conv + Q_dot_rad
(2) Q_dot_conv = hA(Ts-T)
(3) Q_rad = εσ(Ts4 - Tsurr4)


The Attempt at a Solution


After combining equations 2 and 3 into 1 and solving for Ts, I get a 4th order equation. When entering this equation into a solver, it gives me ridiculously high numbers (like 21000 degrees C). Any help would be appreciated.
 
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It would help anyone commenting if you could show your work. It might be something like a mistake in arithmetic, or it might be something conceptual.
 

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