Water from thin air

[mildredx]

I need to come up with an idea of how to get water from the air.  Does anyone have an idea of some I can built.

Please help

[Lord Antares]

There are things like that, for example:

https://www.waterfromair.co.za/

I guess you could google and try to find information on how such a device is built. Why do you NEED to do that anyway?

[mildredx]

I need it for a science project but it cannot be a copy-cat.  I could use ideas from the internet but the design has to be my own.

[MigL]

A sheet of plastic film, horizontally sloped, a few feet off the ground, will cool down much faster at night than the ground.
Warmer, moisture bearing, air next to the ground will rise, water will condense on the cool plastic, nd run down the slope into a container.
This should give you some water for the next day, although I've never done this; Only seen it in movies/TV.

[J.C.MacSwell]

The trick is to get something cooler than the dew point of the surrounding air so that moisture in the air condenses on the surface in a manner that it can then be collected. MigL's suggestion does all that (it can be as simple as a piece of plastic stretched between, say, four rocks weighted down by four more with a small pebble sitting in the middle to get a bit of slope, and a cup underneath the lowest point to catch the accumulating water.

[mildredx]

Thank you, I will try that

[studiot]

Shouldn't this be in Homework Help if it's for a project?

 

16 minutes ago, J.C.MacSwell said:

The trick is to get something cooler than the dew point of the surrounding air so that moisture in the air condenses on the surface in a manner that it can then be collected. MigL's suggestion does all that (it can be as simple as a piece of plastic stretched between, say, four rocks weighted down by four more with a small pebble sitting in the middle to get a bit of slope, and a cup underneath the lowest point to catch the accumulating water.

It's slightly more complicated than that, because the surrounding air is often very (very) dry so your apparatus would have to be very very cold to reach dewpoint.

The purpose of the plastic tent is to evaporate some of the liquid water and concetrate it just under the tent.
This greatly raises the humidity of the air just under the tent.

So this tent does not have to be so cold, in fact you can often see condensation under polythene sheeting.

[J.C.MacSwell]

1 hour ago, studiot said:

Shouldn't this be in Homework Help if it's for a project?

 

It's slightly more complicated than that, because the surrounding air is often very (very) dry so your apparatus would have to be very very cold to reach dewpoint.

The purpose of the plastic tent is to evaporate some of the liquid water and concetrate it just under the tent.
This greatly raises the humidity of the air just under the tent.

So this tent does not have to be so cold, in fact you can often see condensation under polythene sheeting.

What I meant by surrounding air was the air immediately surrounding the cool surface...so probably a bad choice of wording. And as you suggest raising the humidity of that air can also help, especially in dry air conditions.

What MigL described is typically done overnight, taking advantage of the warmth remaining in the soil and the cooler exposed plastic. You are describing something closer to a solar still. It can be quite productive if there is a lot of moisture in the soil, even with the plastic likely to be above the ambient temperature. In this case it is best if the plastic is sealed around the perimeter.

At some point we are crossing a line of getting the water from "thin air" if that is the goal.

Edited October 2, 2017 by J.C.MacSwell

[John Cuthber]

Well, this would be a novel idea for a project

https://en.wikipedia.org/wiki/Vortex_tube

 

[studiot]

32 minutes ago, J.C.MacSwell said:

What I meant by surrounding air was the air immediately surrounding the cool surface...so probably a bad choice of wording. And as you suggest raising the humidity of that air can also help, especially in dry air conditions.

What MigL described is typically done overnight, taking advantage of the warmth remaining in the soil and the cooler exposed plastic. You are describing something closer to a solar still. It can be quite productive if there is a lot of moisture in the soil, even with the plastic likely to be above the ambient temperature. In this case it is best if the plastic is sealed around the perimeter.

At some point we are crossing a line of getting the water from "thin air" if that is the goal.

But the air doesn't usually surround the surface.

Water for instance does not condense on the top surface of the same polythene.

Take a piece of plastic that nowhere near covers or tents a region of air and see just how far you have to cool it to creat condensation on either top or undersurface..

 

So however you cause the evaporation it is also important that the resulting higher humidity is not allowed to escape.

And yes the 'desert still' (also effective in the open ocean) is the ultimate version of this.

To go to forced cooling, you would be talking about desalination plant, which I don't think is the purpose here.

[J.C.MacSwell]

3 minutes ago, studiot said:

But the air doesn't usually surround the surface.

 

It doesn't with the plastic, no. But it generally does for the most part where the cooled surface is exposed to the air. I was picturing a dehumidifier when I initially wrote that before remarking on MigL's suggestion.

[mathematic]

You could buy a dehumidifier.

[studiot]

Yes, the dehumidifier is a scaled down version of the industrial plant I mentioned.

1 minute ago, mathematic said:

You could buy a dehumidifier.

True, the device has apparently to be different from that which someone else has already made.

[MigL]

Uh guys...
I think the OP has lost interest.

[mildredx]

I want to mention that I tested Migl idea last night and the plastic sheet had a lot of water droplets on in.  Did not measure it as I didn't have it in a slope.

Studiot, I just want to mention that this is NOT HW and should not be part of Homework Help! I am doing this with my other science friends as who accomplishes the best result.

Migl and J.C. MacSwell

Thank you for the idea. 

I plan to do the following:

 

I want to experiment with digging a hole in the ground (colder temperature helps reach dew point) and using a sheet of plastic or cone shaped metal that the water will condense on and run down to drip into a container.

Please advise

[DrP]

Sounds feasible - what you propose is similar to what they have already suggested..  Secure the sheet across the hole and put a small weight/pebble in the middle to create the slope...  The water will collect in the sheet.  I guess you could puncture a small hole in the centre too and have a container underneath to collect the drops. This way you will get any condensation collecting under the plastic as well maybe.

 

Good luck.  

Edited October 3, 2017 by DrP

[iNow]

1 hour ago, mildredx said:

I want to experiment with digging a hole in the ground (colder temperature helps reach dew point) and using a sheet of plastic or cone shaped metal that the water will condense on and run down to drip into a container.

Please advise

Good survival trick:

 

Edited October 3, 2017 by iNow

[J.C.MacSwell]

Looks like it was quite effective: Note that it was pretty much as Studiot described and used the Sun to heat the very damp soil. It did not rely on night time cooling.

[MigL]

My apologies for thinking you had lost interest, Mildred.
Planning a trek through the desert ?
Or are you going on a survivor style reality show ?

Edited October 3, 2017 by MigL

[mildredx]

Hello MigL,

LOL Nothing like that, although I wish I was on a reality show to see how long one can go with little bits of water until the finish line.  I belong to a group of science females and we were just thinking if such thing was possible.  We took a look at WATERSEER and they called it a "Busted" experiment.  This forum changed that.  Thanks to everyone here.

[zapatos]

On 10/2/2017 at 0:43 PM, mildredx said:

I need to come up with an idea of how to get water from the air.  Does anyone have an idea of some I can built.

Please help

Seal a plastic bag over some leaves on a tree.

[mildredx]

Zapatos,

From thin air... NOT LEAVES

[iNow]

Will you have access to something cold? Place something cold in the air and water will condense around it.

[Raider5678]

2 hours ago, mildredx said:

Hello MigL,

LOL Nothing like that, although I wish I was on a reality show to see how long one can go with little bits of water until the finish line.  I belong to a group of science females and we were just thinking if such thing was possible.  We took a look at WATERSEER and they called it a "Busted" experiment.  This forum changed that.  Thanks to everyone here.

Actually, in the desert, I do not believe this will be very effective.

[J.C.MacSwell]

5 minutes ago, Raider5678 said:

Actually, in the desert, I do not believe this will be very effective.

Yeah. No magic involved. There has to be sufficient water in the air, and the collecting surface needs to be maintained below the dew point. Tough to do that in very dry conditions.