increased condensation/evaporation rates
increased condensation/evaporation rates
(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





RE: increased condensation/evaporation rates
RE: increased condensation/evaporation rates
Michael McGuire
RE: increased condensation/evaporation rates
RE: increased condensation/evaporation rates
The OD of steam condenser tubes is one big application.
I have tested many coating that do this. The latest are CVD and appear quite durable, but application to long length tubing is a pain.
The question is would the surface texture survive the tube making process (forming, welding, sizing, annealing, straightening)?
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P.E. Metallurgy, Plymouth Tube
RE: increased condensation/evaporation rates
Thanks for your observation. Perhaps we could discuss this. I think I can reach you through Plymouth Tube, yes?
Michael McGuire
RE: increased condensation/evaporation rates
RE: increased condensation/evaporation rates
By the way, internal surface area enhancement IS helpful, as is making the flow turbulent (although it may be that already), but this effect is much larger, as much as a twenty-fold increase in cases of condensation, theoretically.
Michael McGuire
RE: increased condensation/evaporation rates
The problem with enhancements to the ID to generate turbulent cooling water flow is that they are generally not compatible with cleaning and NDT methods. Besides the OD film is the limiting heat transfer component.
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P.E. Metallurgy, Plymouth Tube
RE: increased condensation/evaporation rates
Regrettably it does not exist any more, and back in the day it cost about $200k to build...
The other method is to heavily instrument an few tubes in a real condenser.
If it works then the cooling water exiting enhanced tubes should be hotter than the water leaving regular tubes.
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P.E. Metallurgy, Plymouth Tube
RE: increased condensation/evaporation rates
RE: increased condensation/evaporation rates
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P.E. Metallurgy, Plymouth Tube
RE: increased condensation/evaporation rates
Michael McGuire
RE: increased condensation/evaporation rates
RE: increased condensation/evaporation rates
And today very few utilities have enough technical people to even look at things like this.
While you would think that doing a trial with a few dozen tubes in a condenser at a small combined cycle plant would be easy, it turns out that there is no one to evaluate the potential, design the test, monitor the data, and write the report.
The ranks are very thin today.
Some of us keep plugging away.....
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P.E. Metallurgy, Plymouth Tube
RE: increased condensation/evaporation rates
You might post a link to this post over in the Boiler & Pressure Vessel forum, there are some hx types in there that might have an interest, and I don't know how many cross over into this forum.
Ed, that is scary, but likely true. I know our local utilities contract most everything engineering-ish out to contractors/consultants...