What Makes Aluminium an Effective Thermal Radiation Shield?

[sriram123]

Hi all

I'm doing a project for energy efficient buildings with thermal insulation.(Just a leisure project and I am not technically that strong!)

This is about thermal radiation shielding.

My understanding is that Aluminium has higher reflectivity (Hence lower emissivity ) so that it will reflect all the heat due to radiation to the source itself.

Is there any other property for aluminium that makes it a radiation shield?

Or can I use a steel sheet with aluminium painting to achieve the same effect.(Though Weight will be more but cost will be less).

 

[Redbelly98]

You pretty much want a shiny, mirror-like surface. I doubt that the aluminum paint would be as good as a polished steel sheet, but you could buy a can of the paint and see for yourself how it looks.

Even then, you'd only be seeing how it reflects visible light. What is important is how it reflects the infrared radiation emitted by objects at or near room temperature. For that, polished metal surfaces are generally really good at reflecting.

 

[AJ Bentley]

Paint would be useless. You need a specular reflection to avoid absorption of energy.

You really want pure metallic silver sheet...

 

[sriram123]

I will get a clearer picture if you could tell me the best scenario for thermal radiation shielding

(Sorry cannot afford silver foils or coatings)

1.A single Aluminium sheet (I assume E=0.09)

2.A polished steel sheet or steel sheet with aluminium painting (The paint part, you can see many suppliers are already offering such paints)

3. A series of thin aluminium foils

Please tell me the reason why any of these is a good shield in terms of absorptivity or so.


I would also be thankful if u could provide me links to some material for this matter.

Please don't get me wrong as I learned everything only through experience and I have now only started to learn these through books.

Thanks in advance

 

[sriram123]

Is my Question unclear ?