High Thermal Conductivity Metal Alloy

[hgjor]

I need a metal (alloy) with the highest possible thermal conductivity to use as heat exchanger. I have tried pure copper, but I noticed severe temperature corrosion at 450°C. I have also tried nickel plated copper, but the nickel comes loose at sharp edges.
Does anyone have a recommendation for a metal alloy with excellent thermal conductivity (preferably the same as copper) and high temperature corrosion resistance ? The metal (alloy) will be used as heat exchanger and should not be excessively expensive.
Many thanks for your help.
Herman

 

[btrueblood]

Presumably "temperature corrosion" means oxidation in air? Or can you be more specific about what fluids are going thru your HX. At 850 deg. F (450 C) you don't have a lot of choices, and no alloys that will survive long at that temp. will approach copper's conductivity (silver is the only metal with better conductivity than copper). Stainless steels can work (I would suggest stabilized grades like 347 or 321, or duplex alloys), as will superalloys (Inconels, Haynes alloys).

 

[hgjor]

Yes, you're right, I mean oxidation in air. If there are no alternatives, would copper surface treatment help ? Or replacing the copper by bronze ?

 

[moltenmetal]

Have you analyzed the heat transfer resistances in your exchanger to know that the resistance of the metal itself is so significant as to dominate? If the metal itself is not a significant fraction of the resistance, you have lots of other options which are only modestly less thermally conductive.

 

[EdStainless]

I suggest that you look at high Cr steels, 9% Cr or 13% Cr grades. They will be a lot stronger and stiffer than Cu so you should be able to use 1/2 the wall thickness of your Cu or even less.

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Plymouth Tube

 

[hgjor]

I selected copper because the exchanger temperature uniformity has to be very good. What other options would you suggest ?

 

[EdStainless]

You will have good uniformity with THIN wall steels.
You need to look at the CDA web site and see if there are any Cu alloys that are usable in your temp range. My guess is that they will have Ni and Cr in them and their TC will be less than 1/4 of pure Cu.

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Plymouth Tube

 

[unclesyd]

We used Cu and Cu alloys, mainly Silicon Bronze at your temperatures but we always used a thermally sprayed aluminum on the OD. I don't know if you can get an Al coating on small tubes.
Here are a couple of ideas if you have to get away from Cu and go to a Cu alloy.

Wolverine Tube has various Cu alloy finned tubes available that might work. Using fins will mediagate some of the loss in thermal conductivity from the Cu tubes.

http://www.wlv.com/products/products/Enhanced/enhanced.htm

Ener-Fin makes a Al finned Cu tube that might work and again I don't think you will loose much heat transfer.

http://www.enerfin-inc.com/Fins.html

If you have to get away from Cu or Cu alloys altogather Fin-Fin is another approach to enhance the heat transfer of other metals.

http://www.highperformancetube.com/benefits.htm

 

[metman]

You might want to consider Monel, Nickel-Copper alloy(s).

The heat transfer will be considerably less than Cu but the heat resistance much better and as has been pointed out, geometry can be a large factor in heat transfer. Thinner tube walls plus fins can be used to take advantage of the strength & heat resistance to heat transfer ratio.

 

[GBSC]

Hi,

I found an interesting content regarding quotation on metal injection molding parts on

http://omnexus.com/rd/?rd=213&lr=postengtips

You might be able to find someone there who can quote/advise on the best material/alloy to use.