Blackbody Heat Shields/Metal Sheets

[sweetdreams12]

A “blackbody heat shield” is used to reduce radiant heat loss in situations where standard low conductivity insulation (i.e. normal insulation) cannot be used. The shield is constructed using a set of parallel metal sheets, each with emissivity 1.0.

Explain how/why this “heat shield” works and determine how many sheets of metal are
required to reduce the heat loss to less than 20% of the unshielded value. (Hint: think
about the radiation absorbed by each sheet and how this energy will be re-radiated.)

Diagram:

I really need help with this xD I don't even know where to begin.

 

[mfb]

Here are some ideas:
- assume that the whole problem is 1-dimensional
- begin with 1 heat shield: Where does it receive/emit radiation?
- assuming that the environment has a temperature of ~0, calculate the temperature of that heat shield in equilibrium

 

[sweetdreams12]

ummmm I still don't get it xD

do I use the equation:

Q = mC deltaT?

 

[mfb]

No, that looks like regular conduction.
$P_{emitted}=\sigma A T^4$ (Stefan-Boltzmann)