from a previous post from usenet of Nick's
Nothing very quantitative or comprehensive, but Jim Mitchell and I just
traded some email about that. His "Solar Handbook" (ref?) lists
oxidized
galvanized steel with an approximate alpha = 0.8 and epsilon = 0.3.
Duffie and Beckman list Tabor's 1964 "Nickel black on galvanized steel"
with alpha = 0.81 and epsilon = 0.17, which makes me wonder that the
treatment may not be worth the trouble in some applications, vs just
letting galvanized steel rust...
Nick
The reason I ask is because I want to build a low cost, large area,
unglazed collector and I am toying with some different concepts.
This might be much cheaper than large amount of copper sheets (~$4,000)
that I am thinking of building it out of and letting the copper
oxidize.
>This might be much cheaper than large amount of copper sheets (~$4,000)
>that I am thinking of building it out of and letting the copper oxidize.
The copper can be quite thin, eg 0.005 inch foil.
Nick
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>that I am thinking of building it out of and letting the copper oxidize.