Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: Corvettaholic on May 27, 2005, 01:37:28 PM
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I was once again thinking about how hard it would be to live in the middle of nowhere and still have power and water. As far as the water issue, I've tossed around the idea of condensing water from water vapor in the air. Being that Arizona is really arid, I won't get much water... but something is better than nothing. Found a link to a company that actually makes this device:
http://www.vapaire.com/homepage.html
My question is, how do they do it?
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in all likelihood, it has fractional distillation as its principle...
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What is fractional distillation? Put it in layman's terms for me please ;D
And... how do I do it myself in a practical, redneck sort of way? All my science experiments can be considered extremely redneck. I just like proof of concept.
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They just cool air below Dew point and make it possible to condense water humidity out of it.
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they do that by using a refrigerant
http://en.wikipedia.org/wiki/Refrigerant
so that the machine can work self sufficiently
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The principle is relatively simple. The main problem is to condense water from air by spending minimal possible energy. Our home air conditioners actually do the same job- the air is cooled there below dew point and water condensate unloaded via it's pipe out to the drain. In the other words common used air conditioners spend energy for cooling and drying of air.
As far as I can understand the invention-they built device that spends energy only (or mostly) for drying of air along with collecting of water condensate and (probably) addition of salts for obtaining water close by it's quality to the common drinking or even mineral water( humans can't drink distillted mineral water).
Simplified energy balance for the process could be represented as follows:
E=E1+E2
Where:
E- is overall energy that must be spent to condense water from air
E1-is energy that must be spent for cooling of the air up to dew-point.
E2-is energy spent for cooling of water vapor(humidity) only ,up to dew-point.
What is important is that E1>>E2
Consequently most of the energy actually applied for cooling of huge amounts of the air rather then for condensation of tiny amounts of water in it.
The same problem is exists in distillation of sea water. What you actually looking for there, that is to get rid of dissolved minerals.The energy you need to apply for rendering of dissolved NaCl (and other salts of sea water) to solid state or more concentrated solution, is nothing to be compared with energy that must be applied for evaporation of water. The solution is simple. In modern plants for distillation of sea water the energy is saved by recuperation of heat of distillate. The water distillate just transfers it's heat to inlet flow of cold sea water (that circulated in condensers etc).
Almost only lost of energy are trough heat isolation of heat transfers and pipes.
In the other words if you are going to distill water in medieval way - by heating it up to boiling point and collecting of hot distillate, you should spent, say, one kwatthour of energy for 1 Lit. of distillate. But if you should use hot distillate for preheating of cold water to be distillated, you should be able to collect,say,10 Liter of distillate per 1 kwatthour of energy.
All the described above could be applied for condensation of water from air.
Using of home air conditioners for condensation of air humidity is pretty same to medieval distillation of water, but instead of loosing of energy with hot distillate you do it with cold outlet flow of air.
All you have to do is to adjust additional powerful heat transfer to a home air conditioner, where cooled up to dew-point and water free outlet flow of air will be used for precooling of inlet flow of wet air. Such modification along with changing of power supply, volume rate of air flow and other parameters and parts of air conditioner, will cause sharp raising of amounts of water condensate per kwatt of spent electricity and dropping of it's initial effectiveness as air cooler.
In ideal case the devise should condense water from air and return it dried and almost at room temperature.
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miaskows -
What do you mean by
distillted mineral water
and
( humans can't drink distillted mineral water)
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It was mistaken typing. I meant 'distillated water" sure not "mineral distillated water", sorry. :)
Next time will be more carefull with my writing.
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miaskows -
If you meant to say
"( humans can't drink distillted water)"
You would also be incorrect with that statement as well
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This time i think i do correct with my statement. Sure that noone should get sick or even die if he drinks the distillated water couple of times or even weeks. But human body needs the minerals that common used drinking water is contents. We also get them from our meal, all right, but still you never could be able to find plastic botles of distillated water in your supermarket labeled: "New!! Pure , minerals free distillated water.Drink it and feel difference! With white winged angel giving you golden glass of distillate that should bring your soul faster to the glory and eternity " or sort of it. :)
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What interesting is that the producers of the devise have not mentioned addition of minerals to their water. But they claimed it does meet all standards. ???
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miaskows -
Read this site so you will not continue to perpetuate myths.
http://www.durastill.com/myths.html
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I never felt meself so ashamed. Then all of that staff about minerals and a taste has been myth. Probably. It was very interesting and usefull to read the articile about distillated water. In the other hand it seems like advertisizing , even very persuative and scientifically proved, but still advertisizing. I am sure a company that makes filters or sort of it can get for itself hightly professional explanation why we do must drink water contaminated with minerals and not salts free one.
But still thank you for the link.
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billnotgatez-
If you should suceed to find on net somthing so much persuasive about existence of God, as you has found about harmless of water distillate, i should turn to priest .
I will let to meself to return to the invention.
The main idea of Vapair:
"Our device Needs NO Water Source...Generated Water from the Air We Breathe"
Sounds great.
It could have been sounded much more impressive with follow banner:
"Our device Needs No Water and Electricity Sources... Generated water from the Air We Breathe and operated on the Solar Energy"
I think there is Targed Group of customers that would be interested in such device.
All that have to be done is adjusting of powerfull solar batteries and generator. Then you could be able to carry it with you to nowhere (humidy ,sunny sea coastal desert area or some other wilderness) and to enjoy your drinking.
It will be much more expensive toy, but there would always be somebody that should find it usefull.
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miaskows –
I did not want you to be ashamed, rather educated and skeptical.
The site I posted would normally make me skeptical of both sides of the issue, but my training and readings in other areas makes me side with the article I posted. You might consider the ad hominem argument against the article, but not as a debater. The only negative study I have heard about is when bicyclist and runners over hydrates themselves, which is not someone who is normally ingesting water.
It is my impression that there are systems that distills and filters pure water out of exhaust gasses of engines. I can not think of a way that there would be minerals in that water either, but they drink it. Someone correct me if I am wrong.
Regards,
Bill
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Theoreticaly there would not be minerals in all kinds of water made up by condensation of vapour.
By the way if somebody does want his drinking water to be mineralized , it should be easy to meet his demands by simple addition of previously prepared mix of unhydrous salts or their concentrated solution.
Such operation should not be expensive.
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It is my impression that there are systems that distills and filters pure water out of exhaust gasses of engines. I can not think of a way that there would be minerals in that water either, but they drink it. Someone correct me if I am wrong.
if u mean catalytic converters in cars, then i think the water produced are more used as an engine coolant or just evaporated by the hot gases.
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I think Mr. billnotgatez meant the water that formed by burning of the fuel, for example:
C7H16 + 11O2 =7CO2 + 8H2O
consequently burning of 100 gr of heptane produce 144 gr of water vapour diluted with N2.
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I'm trying to follow how to go about building one of these, and its pretty much using a normal air conditioner and scooping the water out of it instead of letting it drain out? Now how would I need to reroute the plumbing so I get more water and less cooling? Just so happens I'm getting 3 window-mount A/C units for free this week! Some nice chap has graciously decided to donate them to science, my science. Now I just need to convince a company to donate some solar panels and deep cycle batteries...
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My guess is that they have a highly insulated coolant box in the base and then tubes run up from that box into the area behind the grating. There, the moisture in the air is condensed and collected below. There must be some sort of pump mechanism to bring the water to the top of the unit for dispensing. The key would be to use a metal that won't corrode or leech into the water during use. You'd also need a filter to avoid sucking in a bunch of dust. That filter would probably need to be changed pretty often.
To add to the discussion about drinking distilled water, I have heard of studies where they compared many different waters from many different sources with a large sample size and it was found that the "best tasting" waters were those that had relatively high concentrations of magnesium and sulfates. Evian spring water, for example, has high concentrations of these ions.
Also, there is no doubt that drinking large quantities of distilled water will cause leeching of electrolytes from the body. It's a simple equilibrium problem; our bodies operate in a medium with high concentrations of ions (sodium, potassium, etc.) which are essential for life. If you add a bunch of pure water, the equilibrium requires that these ions be diluted to a greater extent than if the water you drink already has some concentration of ions in solution. You're not going to leech out the heavier metals (iron, molybdenum, etc.) because the important ones are concentrated in proteins, but the free ions like sodium and potassium (which are responsible for a host of cellular processes) are not tied up in proteins.
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There are number of possible technical solutions:
1) and simplest one, let us to call it "Cold air Mode":
Q- flow rate of inlet air (with temp t1)
W- electrical energy we need to cool Q up to t2
If you operate your A/C in the winter time you need less energy to condense water from air, because inlet temp. of air almost equal to dew point.
Let for Q=const; t2=const (built up parameters of regulators of A/C)
The only parameter we are going to change is t1:
What would happen in this case?
Your A/C has regulator that just stops it's compressors when temp.drops up to t2. If t1=t2 the A/C is in
standbay. During that time it doesn't spend energy for compressing of freon.
If you direct your outlet flow of cooled air to heat transfer device in such way that inlet flow would enter it in counter -current direction , your A/C would get the same air flow (Q) with lower then environmental temp.
Consequently it would work lesser time than usual and would spend less energy.
But , and it is very important, you are going to collect the SAME AMOUNTof water condensate that you would have been collected during usual operating of the A/C.
Conclusion:
Solution No 1 makes it possible to collect usual (relatively low) quantity of water condensate by spending lesser electricity.
The problem is-heat transfer device. It must be of air/air kind.
(We have not such one in our air conditioners- heat transfer radiators there are of freon vapour/air and liquid freon/air kinds.)
Both freon vapour and liquid freon are much more dense flows that air itself and besides have highter difference in temperature than air/air system, and consequently need pipes of smaller diameters than air.
Simplest air/air heat transfer could be built from long box , inside of it a lot of iron plates making tens of sections. It must be constructed in such way that
first section carried outlet flow of cooled air, second inlet flow of room temp. air, third outlet flow and so on.
The flows don't mixed one with another but only transfer their heat.
Other solution is a box that contain a lot of pipes. Pipes for ,say, inlet flow of air, the remaining space of box between pipes for outlet flow of air.
You probably may find different construction of such devices in net. The trick is to get one that would make the job under flow rate conditions of common A/C but would not be too big or expensive. Without calculation it would be done by simple stage by stage raising of number of sections and searching the result of it. Or you can write down flow rates and temp. of both flows and search for a device that meets the demands.
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Well the way I build things is Thomas Edison style, I just go for it and see if it works, then improve from there. So I think I'll tear apart one of the free A/C units and try to rig up a water collector. Once I get it working as well as I can, then I'll resort to calculations to find the optimal way of putting it together. Until that point, I use free/cheap stuff to keep costs way down. There's a lot of useful stuff sitting around in landfills, you'd be surprised!
As far as filtration, what about using high voltage? Have the water outlet run through a strong EM field and 'grab' metal that way? Then blast the snot out of it with UV-A light to kill the critters in there. UV LED's can be had for a reasonable price, even ones up to 20watts! Then again, blowing 20 watts on a light source IS a big expenditure of precious power...
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Not all metals are magnetic though.
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Hmmm... good point. Any recommendations for a filter system then? Suppose in a pinch I could just a coffee filter. Or use solar heat to boil off water from the collection bin, and re-condense somewhere else without all the floaties following it?
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You can use solar heater for preheating water up to ,say,60 oC and continue heating and boiling by common electrical heater. It is simplest solution (widely used in the world). In the other hand i saw article concerns investigation in that field. They claimed that by exposing to a summer sun of properly isolated box covered with 5-7 sheets of a clean glass (the sheets of the glass were adjusted to the box in such way that there was 5-10 millimeters of air between them) and black bottom, they detected inside temp. of 120-140 oC (!). But it is sort of record.
You migh condense boiling water by using of air cooler.
Even in hot summer day temp. of air raised as high as 45 oC only . It is still pretty good for condensation of boiling water.
Another way -using your cold tap water as cooling medium. Then you have to get big water tank for collecting of outlet water flow.
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Ecpecially elegant solution of recupearation of bin water by using of solar energy could be described as follows:
Distillated salts free water circulated in your closed solar heater (it is important to use such medium and not bin water itself for evoiding deposition of oily organics ,CaCO3 and other contaminants on elements of the construction). That flow heats bin water in counter curient heater up to ,say, 60oC.
The preheated bin water distillated by using of vacuum pump and cooled by air cooler or (better) by cold tap water flow.
You can use very low vacum to get water boiling at 50-60oC.
There are a lot of cheap or even free ,used small vacuum pumps everywhere (chemical plants and other outfits only happy to get rid of them)
Some of them should need some repairment.
Such pump (from my own experience) can work nonstop a lot of time, ecpecially if the vapour is not corrosive (as it is in our case with water vapour).
Small common used vacuum pumps powered by somthing like 300-500 watt and could evaporate a lot of hot water.
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Say, you suceeded by covering all of your roof with solar heaters (of common used design -no exotic parabolic reflectors or sort of it, just glass covered square boxes with pipes inside, the like one can see on every house in the warm countries). Then you would heat up a lot more water than you need for your bath.
Say, as well, that you have got for yourself a small vacuum pump. You can regulate the pump in such way that it would get constant vacum, say, 0.3 Atm. As you know every boiling point value is corresponds to some exact pressure value. Consequently, if you regulate your pump to build up vacuum of 0.3Atm, your preheated waste (bin) water would boil at 60 oC exactly. Water with lower temperature (say,45 oC) would circulate via your distillator and get out without boiling.
The whole system would regulate itself!! There is sun outside there-you collect distillate, cloudy wether- no distillation would proceeds.Properly adjusted and maintained vacuum pump almost would not spend an energy. Distillation of the water even such low temperatures and vacuum would be completely covered by solar energy.
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Water condensor to me makes me think of an A/C as was said already. Why not just make an A/C on steriods. Get some copper tubing and a compressor. I'm sure your smart. I live in NH and it gets humid. Humidity is the killer. It makes things feel so hot. In the winter it gets cold though.
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See, there is NO humidity in arizona. I was using a swamp cooler last week until I got my AC fixed, and that made the house real humid. What about dehumidifiers? Those don't have a compressor, do they? If I can avoid a compressor to condense water, that would be great because compressors eat so much power. I like miaskows idea using a vacuum pump, but I want to go more low-tech than that. The less parts involved the better. Why? Because I have to build it.
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O. I don't know how dry it can get in Arizona. I've never been out there. It can get really humid here in New Hampshire. My toilets are great water condensers. Lots of water drips of the bowl and holding tank. I have to put a towel under it to prevent water damage.
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Relatively Humidity in Arizona ,like in the most desert places ,is relatively low. It is less or around 40 per cent would be my bid.
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Checked on the humidity the other day... 9%.
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Unbelivable :9% of relative humidity! And we have discussed possibility of getting water by condensation of it from the air down in your place! What's kind of filling to live in such place? In the other hand it would be pretty good not dropping with sweat as somewhere in far eastern sity. Has anybody visited Bombey in the middle of summer? With >90% of humidity and 36 degrees in a shadow.
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We just roast, but cool off quick when sweating. And sweat you will. Its like being under a magnifying glass, if you have dark colors on you... you're done. Sunburns are very common too, paint fades on cars, the asphalt is hot enough to cook an egg. I've done it. And ate it. And with all this I want to get water out of thin air? Yup ;D