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Vapor-collection technology saves water while clearing the air

news.mit.edu

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Re: Vapor-collection technology saves water while clearing the air

#3
post #2

This seems like a roundabout way to achieve a closed-loop cooling cycle. Why do this vs a water-to-air heat exchanger and never evaporate the water in the first place?

It does still evaporate, it just condenses back to liquid shortly after. I don't understand the thermodynamics very well, but isn't the point of steam to carry heat _away_ from the plant? I'm wondering if the catch is that the plant would then have to deal with hot water removal instead of just venting straight up and out.

Also,

> What’s more, in many arid coastal areas power plants are cooled directly with seawater. This system would essentially add a water desalination capability to the plant, at a fraction of the cost of building a new standalone desalination plant, and at an even smaller fraction of its operating costs since the heat would essentially be provided for free.

This seems like a no-brainer and it's surprising to me that it doesn't already work this way.

Re: Vapor-collection technology saves water while clearing the air

#4
post #3
post #2

This seems like a roundabout way to achieve a closed-loop cooling cycle. Why do this vs a water-to-air heat exchanger and never evaporate the water in the first place?

It does still evaporate, it just condenses back to liquid shortly after. I don't understand the thermodynamics very well, but isn't the point of steam to carry heat _away_ from the plant? I'm wondering if the catch is that the plant would then have to deal with hot water removal instead of just venting straight up and out. Also, > What’s more, in many arid coastal areas power plants are cooled directly with seawater.…

> isn't the point of steam to carry heat _away_ from the plant?

The point of steam is to turn a generator, these plants are basically steam engines using heat to produce steam for driving a turbine.

Edit: I think I'm wrong in that the steam loop for driving the turbines is isolated from the loop including the cooling towers which is strictly for cooling the closed generation circuit via heat exchangers to condense the steam... you're right.

Re: Vapor-collection technology saves water while clearing the air

#5
post #3
post #2

This seems like a roundabout way to achieve a closed-loop cooling cycle. Why do this vs a water-to-air heat exchanger and never evaporate the water in the first place?

It does still evaporate, it just condenses back to liquid shortly after. I don't understand the thermodynamics very well, but isn't the point of steam to carry heat _away_ from the plant? I'm wondering if the catch is that the plant would then have to deal with hot water removal instead of just venting straight up and out. Also, > What’s more, in many arid coastal areas power plants are cooled directly with seawater.…

Oh sure, there's cases where the output is more valuable than the input. I agree that desalination is possibly quite worthwhile. Though I'd imagine that in the ocean water case that the flow rate is high enough that little water is heated to the point of evaporating. Probably don't want to produce brine or salt residue.

But much of the article talks about how 40% of lake, river, and well water goes into evaporative power plant cooling. Recovering that already-salt-free water via condensation vs just not evaporating it in the first place seems silly. Your car doesn't use evaporative cooling, it uses a heat exchanger. So too could a power plant.

Though if the working fluid is steam I guess we'd call it a condenser rather than a radiator. That said, if you have steam to exhaust you have energy left to extract. My home water heater condenses the steam out of combustion exhaust to achieve good efficiency.

Re: Vapor-collection technology saves water while clearing the air

#7

I wonder if this tech could be applied to evaporative cooling systems for data centers in hot regions to capture the water that is otherwise lost. I know many of the big data centers use a ton of water in areas that don’t exactly have water to spare.

What hot regions use evap systems in data centers? Seems the humidity wouldn’t be worth it and once you dehumidify you might as well use an a/c in the first place.

Re: Vapor-collection technology saves water while clearing the air

#8
> ...vapor collection could be made much more efficient by first zapping the tiny droplets of water with a beam of electrically charged particles, or ions, to give each droplet a slight electric charge. Then, the stream of droplets passes through a wire mesh, like a window screen, that has an opposite electrical charge. This causes the droplets to be strongly attracted to the mesh

Woah, this seems really simple and possibly applicable to other situations where you're trying to condense a vapor.

Re: Vapor-collection technology saves water while clearing the air

#9
> About two-fifths of all the water that gets withdrawn from lakes, rivers, and wells in the U.S. is used not for agriculture, drinking, or sanitation, but to cool the power plants that provide electricity from fossil fuels or nuclear power.

This is fucking stupid. What the fuck are they talking about outside of the environment industrial complex cult HN loves?

Does anyone know?

Is it Thermoelectric power? Or is it as usual MIT outright, day in, day out lying?

Is there any source? I'm not sure what to even check?

This implies it disappears - "leading to huge white plumes that billow from their cooling towers"

40 motherfucking % of supply? Or is the lie "lakes, rivers, and wells" is not a dam? Which is still fake. HN sugar for the mice I guess?

[] The ratio between net consumption and withdrawal is estimatedat less than 5%. It includes water for the cooling of thermoelectric and nuclear power plants, but it does not include hydropower. https://ourworldindata.org/water-use-stress

Re: Vapor-collection technology saves water while clearing the air

#10
post #7

I wonder if this tech could be applied to evaporative cooling systems for data centers in hot regions to capture the water that is otherwise lost. I know many of the big data centers use a ton of water in areas that don’t exactly have water to spare.

What hot regions use evap systems in data centers? Seems the humidity wouldn’t be worth it and once you dehumidify you might as well use an a/c in the first place.

Does a compressor use more energy than a dehumidifier? Seems like there might still be some savings by avoiding the compressor
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