Reflecting Mirrors and Solar Evaporation

While this idea is quite basic, it might also be quite efficient. The link is to a basic diagram.

What has been left out of the diagram is an expansion chamber where the heated water would be in an area with about 26 inches of vacuum. This would allow water that is 122 degrees Fahrenheit or about 50 degrees Celsius to boil.

Reflecting mirrors are used on most deep space telescopes because of their ability to effectively focus light. And by having water flowing in a "stream" that has a black matte finish (absorbs heat, doesn't reflect light well)with a glass covering made from safety glass, the water would essentially be in an oven.

To cool the purified or treated water, a condenser using copper tubes could be used. This would help to preheat untreated water at the same time.

And with reflecting mirrors, they can be tilted towards the sun for maximum reflection. With current parabolic mirrors, copper pipes are heated which have to conduct heat and also have some refraction lessening the efficiency of the system.

Also, by having a glass covering to focus all of the light possible on the water while trapping as much heat as possible, there is virtually no refraction.

And if anyone has any thoughts or suggestions, please feel free to comment on this.

http://i979.photobucket.com/albums/ae278/bessler_supporter/reflectingmirrors_zpsf7117982.jpg

6 Answers

1. Dear James thank you for your illustration, what i like is the ides of converting bike pump into a vacuum pump it's easy,useful, and applicable. so the concept is to heat the water with the help of reflecting surface and when the water been converted to steam pumped and let it condensate into pure water. did i get you correct?

   1 Comment

   1. Tarig, I just thought of something. To keep things simple, have everything sealed air tight except for filling the water to be heated and the water to be drained. As the dirty water evaporates, then condenses as clean water, the amount of water will not change. The pump would be to maintain vacuum (remove air as needed). And when the purified water is to be drained, the vacuum pump could be disconnected, or open the inlet (fill valve). Allowing air into the purifier will allow for the clean water to drain. A tube may need to be placed through the purifier where you want steam to condense. The tube could allow air or other water if you want to help cool the steam. With that thought in mind, putting something over the area where steam will condense might work better or at least help.

2. Tarig, I thought I would mention that if you made one 1.2 meters long with a reflective mirror 1.2 meters long by 1.5 meters wide, you should be able to purify about 3 liters per hour. And it would also let you know how polycarbonate or acrylic plastic works in such a design. I think with using condensed steam to assist in heating the water, you would see some increased efficiency. And if something like this works for you, then I wouldn't be surprised if you have friends who might wish to help you. :-)

3. It's Christmas here so hope everyone is enjoying their day. Tarig, to evaporate about 30 liters per/hr., takes a reflective surface of 36 square meters. This assumes the water is 10 C and solar radiation is 700 watts. This does not consider using condensed steam to assist heating untreated water. Also, the effects of vacuum are not considered. A float actuated valve for flow control would be needed. For something like this, if space is available, length simplifies this concept. If it is 12 meters long, then the reflective mirror on each side only needs to be 1.5 meters wide. Also with length, if condensed steam could flow under the water being heated, then this would increase efficiency. If you want to try this, you can scale it down and then could consider with those results if it is something you think would be helpful to you. 20 inches of vacuum lowers the boiling temperature of water to 70 C. As such, efficiency should increase by 30%. There is a cost versus effort that might or might not make it worth your time. The link is to a basic diagram showing untreated water's flow path to becoming steam then condensing and flowing underneath untreated water. Most construction could be plywood with Plexiglas (plastic sheet) separating the treated and untreated water. The enclosure exposed to reflective mirrors could be plastic sheet but it would need to with stand the effects of steam. It's thickness would have to be considered. acrylic may be necessary as it requires from what I found, 130 C. to bend. http://i979.photobucket.com/albums/ae278/bessler_supporter/Untitled_zps359ab215.jpg

4. Tarig, If you could give me some information like geographic area and if you have any idea of the water temperature, I could probably come up with some estimates for you on reflector size and liters per day. They would not be taking a condenser/heat exchanger into consideration. For something like that, having the condensed steam flow under the water reservoir might be a simple way of saving some energy. Then after that, maybe we could work on a specific design.

5. Dear James you're continuing impressing me with your talented ideas, if you give me more about this theory i can apply it in small scale and try to find out more about it's efficiency thanks for sharing this, I'm really interested in all simple cheap technique of water purification.

   1 Comment

   1. Thank You Tarig. One thing I am aware of is what might help people might not work for a city. There are a couple of different ways this might work. I'll post some specific configurations and see what you think of them. With a reservoir for heating water in, a wood box sealed with a rubber type paint might work. Then it could have a plastic covering on it. The reflecting mirrors could be curved wood with a metalized reflective coating. What would be important is what would be the evaporation chamber. With the heating reservoir, greenhouse material could be placed over it to create a heated air pocket. But when converting hot water to steam, direct reflection would probably be best. The reservoir for heating water could be filled full but it might help to keep the water shallow. It would heat a little quicker. I'll give some thought to what might be a good way to try an evaporation chamber. It would need a pump to remove water from it unless the vacuum is released. If so, then purified water could drain out and then a hand pump could be used to restore the vacuum. One way to modify a hand pump to become a vacuum pump; http://lifehacker.com/5618718/convert-a-bike-pump-into-a-manual-vacuum-pump By the way Tarig, with an evaporation chamber, the reflective area might need to be 2 1/2 times the surface area of what is used to heat the water. And because it is for evaporation, water would need to fill only about 1/2 of it or less. The reflective coating can be found at a gardening supply store or hydroponic shop. I saw it online for use inside greenhouses. Maybe you could ask for a sample if you try it. Then you'll know how reflective it really is. Tarig, This is a basic diagram of how flat surfaces can reflect as curved surfaces. The specific anfgles and dimensions would need to be worked out if you try it. Would need to know what your needs are. http://i979.photobucket.com/albums/ae278/bessler_supporter/ReflectiveAngles_zpsa5a40db9.jpg

6. will it be useful for a bigger capacity? I doubt

   1 Comment

   1. Robert, one of the reasons why I advocate humanitarian aid before commercialism is that idea's can be field tested. Then the potential something has would be better known. What is often missed is around Northern Africa and the Middle East, there are many places where there is more than sufficient solar energy. It could be a matter of logistics, moving the water. Still, around places like Iran and Egypt, it might be viable. What you seem to miss is that if the heat in condensed steam is used to heat water back to temperature (there would be some loss), then about the only heat needed would be the 540 calories per gram of water being converted into steam. And with an efficient heat exchanger, once the system is up and running, most of the solar energy would be used for converting hot water into steam. And if the rate of entropy is known for heating water to be treated with condensed steam, then the operational parameters would pretty much be known. And for something like this, it might even be possible to have it stand in the upright position. It would then only be replacing a glass enclosure for copper pipes. Still, did not read where vacuum is used in such a set up to lower the boiling point of water. Who knows, that might be something that's been over looked as pressure or force/power is usually the norm when work is performed. Myself, I haven't seen many instances where vacuum is incorporated into the design of something. Even the PX Pressure Exchanger uses vacuum to save energy, up to 60% they say for a typical R.O. facility. So I guess with their success, there might be an upside worth pursuing in a design like this.