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Forum Index : Solar : Solar Evaporation Desalination
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I think you would be able to use the clear platic water bottles. As a small personal distiller. Just thinking out loud, what if you cut the top off, so you end up with a funnel and a bucket. In the bottom of the bucket put an inch of water, and a heavy cup or bowl in the middle, heavy so it doesn't float ( a rock may help ). Then flip the top over so its a funnel and fit it on top of the bucket. Leave it in the sun and it should distill enough water to drink. 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
That should work Glenn. It requires an airtight seal at the top where the two parts join so it may be difficult to take the 'funnel' off (if its siliconed in) to get at the cup of distilled water. Perhaps siphoning the fresh water out with a hose? To reuse this thing some means to refill the evaporation well needs to be figured out (another hose?) and the collecting cup ought to be fixed to the center before the 'funnel' is sealed in - it'll be hard to reposition if it gets knocked sideways. Klaus |
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Everard Newbie  Joined: 30/08/2011 Location: TanzaniaPosts: 3 |
I am amazed at your creativity1! Yesterday I was playing around with 6x 12 litre [not 9 litre as I thought] plastic containers and had developed an idea with 2 of them one on top of the other, the top one with a 6inch hole bored out of the bottom and the remaining floor bent up as a drain with the bottom one to be painted black and inserted in the top one... but your idea is just plain clever... I shall try and put it together after today's Idd Mubarak has passed, the shops open and I can get more containers. I would think that the cup could be glued in place and then bored from beneath with a small hole to insert a drain pipe, the whole thing being placed on a decapitated container to act as a reservoir. You may be interested to hear that a friend of mine [has to remain nameless for security reasons] wrote to me this morning: "The "watercone" was in fact invented by a close friend of mine, the late Dr. James Fitzgerald, at the Institute of Aviation Medicine at Farnborough in the late 60's. At that time part of the survival kit in aircraft life rafts was an inflatable " beach ball" type of evaporator which floated on the sea . Jim realised that a cone would be more efficient in capturing the incident energy from sunlight than an equivalent sphere and so the prototypes were built. ( He also experimented with Solar heating systems on the roof of the building - but that another story.) I am sure that one could use big plastic water containers as a basis for a locally made system. They would not be so efficient ; however with tropical sun angles arguably they wouldn't need to be. Being cheap you just use more of them. The theory is quite simple. You put brackish (or salt ) water in via the top to the bottom of the device which is then sealed ( i.e. put the top back on the bottle). Immediately of course the water starts to evaporate and the atmosphere becomes saturated within the container , then supersaturated. This causes droplets to form on the inside of the container which then run down the inside to be collected in an annular channel from which a separate drain pipe can be opened allowing the pure water to run out. I would imagine that at night , as the atmosphere cools this would give the best flow ." East African coastal farmer |
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| grub Senior Member  Joined: 27/11/2007 Location: AustraliaPosts: 169 |
There is a book called The Ten Bushcrafts or something similar that showed how to make a solar still. Dig a hole in damp ground, place a cup in the centre of the damp hole. Cover the hole with clear plastic sheet and hold it down with stones and dirt around the edge. Place a small stone in the centre of the plastic sheet over the cup so the plastic forms a closed funnel over the cup. As the day progresses, water evaporates out of the damp soil, condenses on the plastic and runs down and drops into the cup. All you need to carry is a cup and plastic sheet. |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew I wish there were a way to keep track of posts. I haven't looked at this one for months as I've been busy doing other fun projects. Suffice to say, I will eventually get around to building another oil-filled flat-plate collector and when I do, I'll post the build. Since using a vacuum pump set-up is sounding evermore complicated, my idea is to use a transmission oil cooler mounted in a horizontal position such that water will run through it by gravity. It will be fed with vaporized water (low pressure "steam") from the solar collector's top-most end or maybe even a flat area atop the collector (similar to a hot plate). The oil-filled solar collector will function passively using thermosyphoning, by the way. Again, the only reason I'm using oil is to up the specific heat value of the working fluid and allow me to use a smaller-area collector panel. The water vapor will be forced by its own partial pressure to run through a pipe which allows it to condense inside the oil cooler using ambient wind as a resource for removing heat, turning the water vapor back into water. That's about as close as I can get to anything that will approach any substantial output increase without using a partial vacuum. Don't hold your breath waiting for me to do this, but rest assured, I'll tackle it sooner or later. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1344 |
G'day Guy's, After trawling thru my backup files I came across a PDF I got from the All About Solar website. The pdf is from the mother earth magazine that ended up like every other and charge for downloads so Gary in his wisdom put a watermark on each page showing his website and made it open source but trying to find the same file on his website would be a nightmare.It is an old file but a very good read with a heap of tips and plenty of guides for building one at home using limited materials. ( Gizmo please delete the below comments when you get the file please) The only problem it is a 9 meg file and I have contacted Gizmo and he is happy to put it up for me due to the lower allowed limited on the forum which is very understandable. My problem is trying to email a 9 meg file these days is proving fun but I will get around it (or square it) and get the file to Gizmo. Regards Bryan |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Bryan http://www.cc-file-transfer.com/download.htm Try this one\\ Bob Foolin Around |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
This whole fresh potable water thing is vexatious. Rain that falls straight from the sky is not always pure, industrial pollution, dust, acid rain, even before it hits your roof. Then it picks up more dirt, dead insects, bird crap, pollen and bacteria from your roof before it goes into the big tank to further brew and breed. Desalination is not without it's problems either, but solar is about as close to something for nothing as you will get. But be aware of bugs and flora growing in warm water, and on your condensing surface. Legionnaires disease is now pretty well known to sometimes occur naturally in cooling towers with warm water exposed to air. Desalination is perfectly o/k most of the time, but be aware of the problems of having warm exposed water in sunlight, it makes a perfect breeding ground for many nasty things. Cheers, Tony. |
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| Everard Newbie Joined: 30/08/2011 Location: TanzaniaPosts: 3 |
Well, I tried the inverted top on the 12 litre container and regrettably it didn't work in any productive way. I think the problem was the heavy blue dye concentration in the plastic and the overall lack of light penetration. I painted the bottom matt black and later tried other configurations but no dice. It may be that ordinary litre bottles in series and on their side may be a better bet - I am trying to collect a lot to try another experiment. With the big ones I even tried a tower 6 feet high but not real production. In the meantime to deal with my agricultural saline problem via distillation I have put two Chromagen panels in series and run brackish water through that and it reached boiling point with sun overhead - so next I plan to run the output into a boiler with a copper pipe coming out and going into a car radiator [just got that] immersed in a barrel of cool brackish water newly pumped from the depths. Weather now dull overcast - unusually for th.eis part of the world. As to the cautious comments on rainwater, it may be area dependent but here we drink our rainwater off the roof without problems. I filter out the bugs, some droppings and lizards with mosquito mesh on three downpipes on two buildings and then store 15000 litres in a tank extension. The water is, of course, not pure but providing you are used to it there are no problems. Better for all purposes than any water I have ever had in the developed world. [Bread making is much superior with rainwater.] I have a large network of tanks on the farm and collect over 30,000 litres in the rainy season. Funnily enough I built my house to automatically collect rainwater and the local builder built the house slanting towards the sea so I was unable to run all of my collected water directly into my inhouse tanks on the landward side and so now I have to in addition pump from a ground tank on the sea side back up to the inhouse tanks. The perils of building in Africa... East African coastal farmer |
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