Emissivity, radiation and heat transfer

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SUMMARY

The discussion focuses on calculating the temperature of the inner wall of a space station with a total surface area of 580 m², an emissivity of 0.62, and an outer surface temperature of 156 K. The relevant equations include P = σA(T^4 - To^4) for radiative heat transfer and P = kA((Th-Tc)/L) for conductive heat transfer. The outer surface loses heat to the cold environment at 0 K, and the heat generated within the station flows through the wall. The key insight is that the power lost through conduction equals the power emitted into space.

PREREQUISITES
  • Understanding of thermal conductivity (k) and its units (Wm^-1K^-1)
  • Familiarity with the Stefan-Boltzmann law for radiation (σ)
  • Knowledge of emissivity and its impact on heat transfer
  • Basic principles of heat transfer, including conduction and radiation
NEXT STEPS
  • Study the Stefan-Boltzmann law in detail to understand its application in thermal radiation.
  • Learn about heat transfer calculations in multi-layer walls, focusing on conduction and radiation interactions.
  • Explore the concept of emissivity and how it affects thermal performance in engineering applications.
  • Investigate thermal insulation materials and their properties in space environments.
USEFUL FOR

Engineers, physicists, and students involved in thermal management, particularly in aerospace applications, will benefit from this discussion.

CeeCoops
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Homework Statement


A space station in outer space (far from the sun) has a total surface area of 580 m^2 with emissivity of .62. The temperature of the outside surface is 156 K. the walls are .25 m thick with an average thermal conductivity of .038 Wm^-1K^-1. Find the temperature of the inner wall of the space station, assuming that the outside surface radiates into an environment that is very cold - essentially at 0.0 K.

Homework Equations



P= σA(T^4 - To^4) and P= kA ((Th-Tc)/L)

The Attempt at a Solution

Just not too sure where to start...does the outer surface of the wall lose some of its heat to the surroundings and then we try to determine how much heat will be transferred to the inner wall? thanks for any help :)
 
Last edited by a moderator:
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CeeCoops said:

Homework Statement


A space station in outer space (far from the sun) has a total surface area of 580 m^2 with emissivity of .62. The temperature of the outside surface is 156 K. the walls are .25 m thick with an average thermal conductivity of .038 Wm^-1K^-1. Find the temperature of the inner wall of the space station, assuming that the outside surface radiates into an environment that is very cold - essentially at 0.0 K.


Homework Equations



P= σA(T^4 - To^4) and P= kA ((Th-Tc)/L)



The Attempt at a Solution

Just not too sure where to start...does the outer surface of the wall lose some of its' heat to the surroundings and then we try to determine how much heat will be transferred to the inner wall? thanks for any help :)

Heat obviously travels from the inside to the outside wall. The space station is generating heat which flows thru the wall to deep space at 0K.

Your emissivity equation is for a black body (α=1). If α < 1 how should that equation go?

So all that's left is to realize that power flowing out of the platform by conduction = power dispersed by emission to cold, cold space!
 
Last edited:

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