3D Printing Heat Exchangers (Air/liquid)

[kripley]

I am working on a project this summer at the University of Wisconsin-Madison, and I am trying to design a heat exchanger that can be made with additive manufacturing methods. We think there would be many advantages, such as reduced cost, fewer limits on geometry, fitting in tight spaces, quicker iterations, and reduced weight. The URL below is an initial pitch for our idea. If you'd be willing, please watch and leave some feed back here or on YouTube. Again, this is a project that I'm really excited about, but I have no clue what the overall impression is from professionals across the country, so please let me know your thoughts or concerns. Thanks!

https://www.youtube.com/watch?v=jYfq4gmDky0

 

[IRstuff]

The models made by 3D printing do not have smooth surfaces, which would seem to be resistance problem.

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[tys90]

There seems to be some research into smoothing 3D printed parts using acetone vapor baths but I'm not sure how that would affect the integrity of a complex part like a heat exchanger.

I'd be curious to know what the temperature limits are of these 3D printed materials. A quick google makes it seem like ~180F is about the limit, about the same as other plastic HVAC/piping products, which makes sense. Limits the use of these in hot water applications.

 

[AWloo]

I have heard of using plastic heat exchangers for highly corroding fluids (especially oversea oil production which uses salt water as a cooling medium). The issues I am aware of for plastic are its lower thermal conductivity, requiring a higher surface area of the heat exchanger to compensate.

The 3D printer we use for prototyping does not produce water tight parts if there is a surface countour. For vertical and horizontal buildups we can get reasonably air tight. To accommodate this we end up coating the whole thing with marine grade epoxy. My concern is that you would have a leaky heat exchanger without any coating. Our resolution of the printer is 0.1 mm. The addition of the heat exchanger further reduces the overall heat transfer coefficient.

 

[kripley]

IRstuff: Yes, we need to study how the relative roughness affects heat transfer. Some machines create surprisingly smooth surfaces, and hydrophobic surfaces are even possible.

tys90: We were considering computer cooling and refrigeration as possible applications. Acetone vapor baths, very interesting. That might be tough to get an even distribution through many small, wavy channels, but we will look into it.

AWloo: Would printing the contoured parts at an angle allow for better air tightness? We have samples of a pressurized water device from a 3D prototyping company, using an SLA machine, and I don't think they use epoxy or any coating. I'm not entirely sure, but one of their materials exhibits characteristics similar to polycarbonate. We will see how this might be useful in marine applications. Thanks for the heads up!