Leaching considerations with reactive heat sink materials... 1

[shane21]

I need to cool a slow moving small flow of hydroponic plant water, at most 1000 ppm nutrients, with a pH of typically around 6.

I'd like to use aluminum or copper heat sink directly in that fluid stream to drop temp 10 or 20 degrees F down to 50-60F neighborhood.

My concern is I don't want to contaminate my fluids with copper or aluminum reacting to and leaching off into the fluid.

Is that likely an issue and if so, is there any spray coating or other such treatment onto the surface of the heat sink to minimize that happening that does not greatly degrade the materials thermal conductivity?

Thank you for any thoughts.

- Shane

 

[EdStainless]

Don't use Cu, at least not pure Cu.
IF the flow is slow then your heat transfer will be very low.
Any Al should work fine.
Are there any other metals in the system, in contact with the water?

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P.E. Metallurgy, Plymouth Tube

 

[shane21]

EdStainless,

Thanks for comments.

No other metals, other than perhaps some micro nutrients in that nutrient solution.

- Shane

 

[IRstuff]

Aluminum is susceptible to phosphoric acid.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[georgeverghese]

Aluminum leaches out easily into solution over a wide range of pH, and is a potent biological poison. However, there are some aluminum grades good for seawater application - check if these marine grades are compatible with the nutrient slate at these low concentrations you've got, in what appears to be a fully aerated solution stream.

 

[shane21]

IRStuff & georgeverghese, thanks both for comments.

Elsewhere I'd also read that there are conformal coatings with good thermal conductivity
and that a coated aluminum part is probably a good balance between cost and performance.

- Shane

 

[chicopee]

Bronze is used for marine application and may be an answer.

 

[John2025]

Of course, make sure you use lead-free grade of bronze.