Is there any advantage over a stainless steele wort chiller opposed to the trusty ol copper?
Price is about the only one I can think of…
price - and stainless is a little easier to clean and will hold up better in an acidic solution such as beer over time.
Copper has a much higher thermal conductivity than stainless steel - about 400 W/(mK) versus 15 or 20.
I’d assume that means that a copper chiller will cool the wort more quickly than a stainless steel one, all other factors being equal. But I haven’t done any calculations, so I’m not sure how great the difference would actually be. Probably fairly small, since your average immersion chiller as a wall thickness of much less than a meter. That and copper and stainless steel pipes probably don’t need the same wall thickness, perhaps steel pipe ends up being enough thinner to mitigate a lot of what difference there is. So maybe it’s not really an issue in practice.
I Googled a bit and I couldn’t find any stainless tubing that had a wall thickness anywhere close to its counterpart in copper, e.g., 28 mils for copper and 65 mils for stainless for 1/2" tubing. Thinking about it purely from a heat flow standpoint, heat transfers to the flowing water 20 times better through a resistance 2.5 times less in copper compared to stainless, so I would think there would be quite a noticeable difference. It would be fun to see an experimental test of this.
Might be fun do do a back-of-the-envelope calculation for starters. Was that 1/2" ID or OD?
Copper vs. SS again. The big resistors in the ciruit are the liquid to metal conduction coefficient, especially if you are not stirring the wort. If you run numbers through the equation, you find that the SS is about 89% as efficient as the copper for an imersion chiller.
Copper adds ions that are beneficial for yeast health.
SS will be more durable - and shiny!