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Charged Superhydrophobic Condenser Surface May Make Power Plants More Efficient
New submitter _0xd0ad sends this news from the CS Monitor:
"The activities of bantam water droplets in just one region of a power plant could make a significant difference in the output of power plants, scientists say. ... When a water droplet forms on a sheet of metal coated with a superhydrophobe, the droplet can camp there only so long as it does not merge with another droplet. As soon as it weds with another droplet, the energy produced is so great that the two will 'jump' away from that surface, as if in urgent deference to the surface's severe water phobia. Scientists have proposed that this 'jumping' could be incorporated into power plant design. ... 'To have the most efficient condensing surface, you want to remove the droplets as early as possible,' says Dr. Nenad Miljkovic, [postdoctoral associate at MIT and co-author on 'Electrostatic charging of jumping droplets']. But, in prototypes, this 'jumping' design is not as efficient as engineers believe it could be. Some of the droplets will just fall back to the condenser's surface, recoating it and slowing the process down. ... But a newly discovered component to the 'jumping' process might allow scientists to eliminate this fall back. In an accidental find, the MIT team found that droplets don't just spring from the surface — they also rebound from each other ... because an electrical charge forms on the droplets as they flee the hydrophobic surface. So, if a charge is applied to the condenser system, the water droplets can be electrically prevented from returning to the surface, he said.
This allows condensers to have a smaller area.
FINALLY!
Sounds like Star Trek technobabble.
The efficiency that is mentioned is water recovery/usage efficiency, not electrical efficiency. In this case a power plant would use more electrical energy to produce the condensation. This is still good news in that it could reduce water usage which is a big issue with power plants in the water starved west.
No, sorry OP, you're gonna need to spell out exactly why it'll make things more efficient. Start from the assumption I don't know what a 'bantam' water droplet is, cos, as far as I understand it, powerplants make electricity by heating up water into steam (via coal/gas/nuclear/whatever) then expanding it through turbines to spin generators. Where, in that process, does this efficiency gain come in? Where is this 'sheet of metal' that drops are forming on? What drops? Why are they forming there? How is stopping them gonna improve this? What sort of efficiency gain are we talking about here?
There's more to Christianity than faith-based belief in intangible entities, you know. For example, the whole "peace, love, and brotherhood" thing that the religion is based on.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
You must be new here if you're going to attack the CS Monitor on its name.
If the droplet leaves with a charge, the opposite charge remains and counters the condenser charge, so you need to replenish the condenser charge. At some other point, the surplus charges of the droplets need to be siphoned off. If the movement is supposed to be effective, you will have to maintain a voltage difference, and a current corresponding to the number of droplets. That means that you need to invest power to keep the process running, with a resulting higher temperature of the condensed water. Will it be worth it?
AC with an EE?
That is one of my questions also. In microbiology this type of effect is everywhere. The nature of polar and non-polar molecules is the key to the cell bi-layer and is self assembling in the fact that polar loves polar. The natural process of body cooling incorporates hydrophobic elements in the cooling ducts. I don't see how this is big news. I would like to see some more information on Dr Sadoway's work at MIT on the liquid metal battery. If he is correct it would help more than this by many orders of magnitude.
Conversely it would be better if the outside of beer glasses were more hydrophilic, because the longer every drop of water can be delayed from rolling off the surface and leaving more room for condensation to take place, the more time we would have to drink the beer at a suitably low temperature.
I just got to tour a power plant - very interesting! The running units were all combined cycle (close to 60% thermal efficiency), and the volume difference on steam in/steam out is really tremendous! The steam was vacuumed out of the LP turbine. And they were complaining about their cooling/condensing system not being efficient enough in the summer to run the plant at full power. Interesting too that the vast majority of the plant was about steam generation/handling/reheating/processing. The turbines and generators are a tiny, albeit critical, piece of the plant.
Also interesting is the sheer quantity of backup and emergency systems. And the generators being cooled with hydrogen and therefore hydrogen lines running all over the plant.
The Monitor is actually a pretty good news source, for the most part. They typically run a single CS article per issue, and are otherwise pretty non-religious. You should take a look before being too critical. IANACS
No. Just flogging a well flogged horse.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Super-hydrophobic coatings are now easily available. They work very well when new, but customers complain about the coating wearing off rapidly. Something with a more durable bond will be needed.
This is yet another of those materials science articles which jumps from "minor discovery in materials science" to "huge commercial breakthrough Real Soon Now." It's bad for MIT's reputation that they put out so much hype.
You know what kills heat transfer? Scale. This system will die (i.e. drop to not so fancy smancy levels) as soon as the scale builds up.
- a chem. eng.
I come here for the love
No, it's your interpretation of the term that's chock full of whatever. The term itself is generic and innocuous.
An enigma, wrapped in a riddle, shrouded in bacon and cheese
For any particular pressure (or vacuum) there is an associated dewpoint temperature. In this case, it is where the liquid water condenses from the steam. Condensers use cooling water to remove the heat of condensation and subcooling. Cooling water is often cooled by evaporating some of the cooling water in cooling towers, so that fresh makeup water is needed. The steam condensate is recycled to the boiler to be heated and vaporized back to steam to power the generator turbine.
However, the condensed water adhering to the condenser tubes is further sub-cooled below its dewpoint. This means that more cooling water is needed, more condenser surface area, and more energy to reheat and vaporize condensate back to steam.
I speculate that the technology described reduces the amount of condensate subcooling, leading to less cooling and heating duty, improving overall efficiency.
Prove anything by multiplying Huge Number times Tiny Number
I don't discriminate. All religion is nutcase. The difference is just a matter of degree.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Would a coating like this help lower the weight of water clinging to the inside of an insulated steam balloon?
They ARE out to get you simply because They are in it for themselves and they don't care about you.
In power stations a vast amount of work and expense is already devoted to removing minerals from the boiler water, since they are not very good for the turbines. Dissolved minerals may be an issue elsewhere but not in the situation described in the article.
The chemistry is very simple because there's not much in the water - normally just an additive to scavenge oxygen. All the difficult stuff is taking care of at the "polishing" water treatment plant before it goes anywhere near the boilers.
No it isn't. Those words have meaning. That's what words are for. To convey meaning.
People have differing interpretations of the same words, based on their individual preconceptions and prejudices. That's what people do - understand the meaning they want to understand.
If things were as simple as your post makes them out to be, there would be no debate as to the meaning of Constitutional Amendments.
An enigma, wrapped in a riddle, shrouded in bacon and cheese