Reflectivity of ALuminium Foils

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Discussion Overview

The discussion revolves around the thermal reflectivity of aluminum foils, particularly in the context of using them as solar reflectors in a parabolic dish application. Participants explore the properties of aluminum foil and its effectiveness in reflecting thermal radiation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the exact thermal reflectivity of aluminum foils used at home.
  • Another participant suggests performing a Google search for the information.
  • A participant expresses their intention to use aluminum foil for a solar reflector and cites a Wikipedia source indicating a reflectivity of about 80-88%.
  • It is noted that the reflection spectrum of aluminum varies with wavelength, particularly for thermal wavelengths greater than 800 nm.
  • Concerns are raised about the impact of crumbling on the foil, which can reduce specular reflection and lead to diffuse reflection, affecting the directionality of the reflected light.
  • A participant shares their practical experience with aluminum foil, stating it works decently for their application despite some scattering due to crumbling.

Areas of Agreement / Disagreement

Participants express varying levels of certainty regarding the thermal reflectivity values and the effects of crumbling on performance. No consensus is reached on the exact reflectivity or the best practices for maintaining the foil's reflective properties.

Contextual Notes

The discussion includes assumptions about the definitions of thermal reflectivity and the conditions under which aluminum foil is used. The impact of surface condition on reflectivity is also noted but not quantitatively resolved.

RKD89
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Can Anyone tell me the exact THERMAL reflectivity if aluminium foils used at home?
 
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Have you tried a google search?
 
Why do you want to know?
 
i am thinking abt using them for a solar reflector ( parabolic dish)
n I Tried googling....wiki says it's abt 80-88%
 
RKD89 said:
i am thinking abt using them for a solar reflector ( parabolic dish)
n I Tried googling....wiki says it's abt 80-88%

That sounds about right. I doubt you can do better better for the cost. What you seem to be looking for is the "reflection spectrum" of aluminium, because the value depends on wavelength. By "thermal", you are practically referring to wavelengths that are greater than 800 nm (near to mid infrared).

The slighest crumble in the foil however will reduce the specular reflection. So if you want to direct the reflected light, you want to reduce crumbling to a minimum. Crumbling of foil turns it from a specular (mirror) reflecting surface to a diffuse (white) reflecting surface.
 
Dr Lots-o'watts said:
That sounds about right. I doubt you can do better better for the cost. What you seem to be looking for is the "reflection spectrum" of aluminium, because the value depends on wavelength. By "thermal", you are practically referring to wavelengths that are greater than 800 nm (near to mid infrared).

The slighest crumble in the foil however will reduce the specular reflection. So if you want to direct the reflected light, you want to reduce crumbling to a minimum. Crumbling of foil turns it from a specular (mirror) reflecting surface to a diffuse (white) reflecting surface.


I have already tried d foil...works quite decent...
Of course the crumbling does result in some scattering...but in all it serves my applicaition
Thanx anyways
 

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