Is a black anodized aluminum heatsink really any better than an anodized silver colored heatsink?

Question

Wrt ability to dissipate heat.

Answer 1

no, the difference is small.  Most heat is dissipated by convection, very little by radiation.

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Answer 2

Hi

If they are both same material, construction,size then black heatsink is definitely better because:

1) black color definitely better radiates the heat;

2) paint(even silver or black) makes some additional thermal resistance.

Have you seen that heat transfer lines are coated in [metallic silver] coating to additionally reduce heat loss.  

Answer 3

i dont know of a difference, and i am pretty well educated in heat shrinks. ive never heard of a difference between silver ( ti?) and black (some type of Ni coating).

this is what lithiumdeuteride said on yahoo answers when i did a search (why didnt you?). sounds correct to me. although i remember the equation having 30+ variables...

Radiative heat transfer (heat transfer by electromagnetic radiation) is proportional to

e*(T1^4 - T2^4)

where T1 is the absolute temperature of the material, T2 is the absolute temperature of the surroundings, and e is the emissivity coefficient.

A black material has a high emissivity coefficient, while a silvery material has a low emissivity coefficient.

However, the emissivity coefficient cuts both ways, so to speak. A black material in thermodynamic equilibrium with its environment absorbs more radiation, true. But it also emits more radiation (this is necessary for equilibrium to hold). Likewise, a silvery material absorbs less radiation, and also emits less radiation.

Conductive heat transfer ensures that the black material on the surface of the heat sink remains hot. The surroundings are at a lower temperature. Therefore T1 and T2 are set, and the heat transferred from the heat sink to the surroundings is simply proportional to e, the emissivity coefficient.

Answer 4

No, silver aluminnum heat sink is better. Black paint insulate the heat and it obsolves more heat if the sun shine reaches it. Manufacture paints it black just for beauty purpose.

Answer 5

Yes. The radiant capacity is higher.

Most of the heat is dissipated by convection at lower

temperatures though, and the difference might not be

worth the expense.

Answer 6

Yes it is, but you should still consider the design and the size.