heat transfer improvments
heat transfer improvments
(OP)
I'm a materials guy who has made thousands of tons of stainless steel for pipe and tube. My question is, would there be value in a micro surface finish on heat exchanger surfaces (one that does alter dimensions or change traditional surface appearance; not a coating) which causes low surface energy, therefore hydropohobicity? It has been widely accepted that this would cause drop-wise condensation and nucleation sites for boiling with a many-fold increase in heat transfer rates, but I would like to hear what the real practioners in the field think.
Michael McGuire
This was posted on another forum, but it was suggested I poll this group.
Michael McGuire
Michael McGuire
This was posted on another forum, but it was suggested I poll this group.
Michael McGuire





RE: heat transfer improvments
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: heat transfer improvments
Ill try to look that up. we have seen a enhanced resistance to impurity pick-up, but I see the logic in what you cite. We have found cavity size to have a critical upper limit, so if I can find the original Union Carbide patent, I'll post the comparison.
Michael McGuire
RE: heat transfer improvments
Thanks very much again. There was a lot of work done from 1980 to 2000, which used three principles:
1. Attaching fine particles to surfaces to increase area exposed and render flow more turbulent. These would be expected to foul.
2 Lining with a low surface energy material, such a PTFE, to cause droplet formation. Such liners are short-lived because of their fragility.
3. Reverse embossing protrusions onto the surface to create turbulence. This works only to alter when the flow is otherwise laminar, a small segment of for enhancement.
Our principle is making indentations sufficiently fine that pick-up of solids and wetting of the surface is much decreased. The size is proprietary for the moment, but it is enough to make a bare stainless or titanium surface behave permanently like closely to a PTFE surface, i.e. contact angle about 90 degrees. See photo below in the attachment.
Michael McGuire