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WATER. Cool, clean, chemical free, salt free, bug free, drinkable irrigable WATER. We live in an environment laden with it, but most of it is completely unsuitable for human use- or the use of our plants which give us life, or our critters. This is not good; we suffer from scarcity in the midst of plenty!

FRESH Water. There is a huge supply of it all around us in Florida (were we live and work here at Freehold Marketing), and if we deplete it, the rate of oceanic evaporation would INCREASE due to the dryer condition of the air, resulting in a resupply of it. For this ocean of fresh water I am talking about is IN THE ATMOSPHERE.

Water is in short supply here in Florida, believe it or not; DEEP down is a large supply of SALT water; floating on it is a smaller bubble of superb FRESH water, and on top of that is a thin skin of organic breakdown CRUD contaminated and smelly fresh water which is not AS good for drinking- or industry or cooking or much all anything, it's nasty stuff. Shoot, it even colors everything rust color (from organic compounds, not rust) when we pump it up to irrigate our lawns. It works, but it's nasty- and in a drought, it dwindles away to nothing rather rapidly. We look wet, but we suffer a drought every spring, SOME of them severe, and we need more and more and more every year, as WORLD + DOG move here to live, to work, to retire, to run away from problems...

Water, it does a body more good in more ways than milk ever did, and bloody near everything else needs it as well; it's sometimes called 'the universal solvent' it is so useful. Water is the most commonly used industrial chemical of ALL chemical compounds.

We live in Pinellas County, the western side of Tampa Bay Florida, which is a major population center; our county of residence owns a working desalination plant. It cost us a very pretty penny, and it take a lot of power and money to run, but it turns out a lot of water- at a steep price. Ah, how could we harvest this ocean of fresh water all around us already?

Here's a simple experiment for you; go get a BIG (intact; no cracks or holes) metal or glass water tumbler; fill it with ice. Then fill it almost full of water, and sit it on a coaster and watch it. Hmmm... it's getting wet. VERY wet in time. A pool forms around it. IS IT LEAKING? No, it's CONDENSING, for it's temperature is well below the dew point for the air coming into contact with it. therefore, water CONDENSES out of thin air, and runs down to- whatever stops it, such as a collection tank. Your air conditioner does this, and has a pipe that goes outside, or a hole or short tube out the bottom, which drips pretty steady when in use. This is water the evaporator stripped out of the air as it got cold passing through the machine, water condensing on the very cold fins of the evaporator. (We call it that because inside this is where the refrigerant is evaporating at low pressure and absorbing heat, making the metal become quite cold.) BTW, this condensate water is perfectly safe for plants, animals, and storage batteries- because it is distilled water.

Vaporators were first speculated in the book (then the movie biased on it) called Star Wars, a significant stage of which takes place on an arid (not totally waterless, just no exposed standing water) world. There farmers grew crops in underground hydroponic gardens, using water collected by condensing machines called vaporators. Gee, Florida and many other places could put that sort of tech to work right quick, if it only were cost effective. How could we do this?

First, we need basic facts about atmospheric moisture. So let's gather up some.

(Courtesy wikipedia; see 'http://en.wikipedia.org/wiki/File:Dewpoint.jpg'.

Also:

BOTH:Pressure and maximum content of water in Saturated air
from http://www.engineeringtoolbox.com/water-content-compressed-air-d_1275.html

OK, this shows us where it happens on the temperature curve for different relative humidity levels. Note the page linked also gives some pretty interesting math for them who do not shrink back from it. One can also gain a great deal of understanding or at least confusion from the math this fine page offers. As a rough stage at interpretation, it means that at 80° F, one atmosphere (sea level) pressure holds .1 lbs per 100 ft³ of air, which is 1.6 ounces. so a pint will take 1000 foot³ of air to become bone dry to fill that 1 pint water tumbler. Hmmm... Good thing Florida has LOTS of wet air... Less than perfect efficiency of the extraction process means we have to process more air to make our required volume of water- possibly also requiring more power as well. So if the process is 50% efficient, it takes 2000 foot³ to create one pint of water. We need a LOT of wet air to turn out a household's day of water- which Florida is very well provided with. Better, let's talk about the amount used by one person in one day, which is 1 man/day of water; that is about 123 gallons, or 466 liters, a stat I harvested from http://www.enotes.com/science-fact-finder/energy/how-much-water-does-an-average-person-use-each-day.

For the general audience, suffice to say that the simple way to extract water out of air is to get the air cold. This means 'destroying' heat, or moving it someplace else. Given the choice of these two games, moving it is simpler and less expensive than creating a process that absorbs heat and turns it into something else, such as a change of state. Melting ice for example, or changing a chemical mixture in an endothermic reaction (IT ABSORBS HEAT). your air conditioner let's refrigerant boil in a low pressure area, which means it is changing state, and boiling absorbs heat. It is doing this at a very low tempreture, like 38*F (10*C) so air blowing across lots of really cold fins of aluminum (which conducts heat really nice) gets cold for you- and while doing this, water condenses on the fins. But mechanical refrigeration takes a lot of power.

So our game plan is a way to make something with a large surface COLD, and pull or push air through it. We need to dispose of the heat this process hands us, and we can shove it into a large structure and let the now dry air blow through it, and reclaim it's heat- and the extra waste heat generated by the heat pumping process. However, the water in the condensing structure drips down into a collector, and we insure the wind velocity in that part is insufficient to blow that all important water UP into the heat sink structure, where it would simply evaporate again. Using one blast of wind to do both jobs is improving our system efficiency, and suggests a structural form- a chimney.

Chimneys operate on the principle that hot air is lighter than cold air, and therefore has buoyancy, and rises if surrounded by cooler air. So our heat sink has lots of air passages through it; the air within it becomes hot, and rises up- creating low pressure at the low end. This is why a chimney draws, and pulls in smoke from a fire under it. Well, this time the chimney is hot and the air in it BECOMES hot, and rises, drawing in the air under it- which is the top of the condenser structure. We could even put a black sheet metal tube on top of this part to superheat the air and help increase the air volume that is drawn through the system. Again, daddy sun is the power source of this thermal wind tunnel.

The condenser is a wide fairly short structure so that wind velocity is low (to prevent windblown water going UP instead of down), and is COLD, but not so cold as to freeze, which in time would build up enough ice to plug everything up and demand a service call; people time is EXPENSIVE. Air comes in at the bottom due to the suction of the low pressure at the bottom of the chimney. Between them is the heat pump device, to keep 'tubing' short. Notice this approach employs thermal siphoning to move air, not mechanical fans; the less mechanical equipment employed, the lower the maintenance overhead. On top we can put a passive thermal tube to help improve volume throughput; not a big puller, but CHEAP, and very reliable. It's black sheet metal, probably aluminum, and covered with weatherproof thin but dark paint. Some solutions are THAT simple.

Given the recent increases in solar photovoltaic technology, we could run this on DC generated by solar cells on panels facing Se, S, and SW, or we can just plug it in to the local mains with a suitable power control and conversion circuit. WHAT that looks like depends on what the heat pump is. If it is a classical motor/compressor/refrigerant system, we need to pull maintenance fairly frequently, as it is mechanical; if it is solid state semiconductor or the new experimental thermo-magnetic heat pump technology, nothing moves and it can stand in place a LOT longer before doing inspection and maintenance. Thermo-acoustic technology might also be a winner here, as long as we can contain the sound of operation; recently there has been considerable improvement in this field, and it is now quite reliable as well as operational at modest costs. Unless TM methods improve a lot SOON, we will probably go with TA refrigeration.

Remember, human technicians cost a LOT more than almost anything you can name, a fact which justifies a lot of slip stick sliding and head scratching- and up front investing in fancy gadgetry. We can even place a sheet metal tube on top painted black to help use solar heat to suck air up the chimney, increasing volume throughput. We even could place a wind directed cap on top on rollers which is open on the 'back' (the downwind side) and let the wind create a minor reduction on pressure on the outlet so as to further improve throughput- with the only moving part being the cap, sitting on rollers on top of the 'stovepipe' section. Maintenance is low, cost is cheap, and it's a pretty reliable tech, if the turbines on top of house roof's is any indication.

The condensing section is somewhat wider to keep velocity in that part lower, not as tall as the upper part is, and joined to the chimney part with a taper to form an airtight column. The heat pump is inside this section. This sits above the condensate drip collector below, which in turn rests on the concrete pad. The collector is probably the top of the storage tank. Up the middle we put a support stalk which lends strength and stability to the entire stack.

At the bottom we need a broad strong solid foundation so it never blows over in a storm; the stalk is BOLTED DOWN to the metal reinforcing frame embedded in the concrete, to insure this thing goes NO-PLACE, even in a vigorous thunderstorm (and is also well grounded as a side effect, which with our lightning is a Great Good Thing®). QAlso, we use something to collect the condensate, such as a covered storage tank using a sloped conical cover with a few drip hiles around the edge so water runs out and down, drains through, and is not lost to evaporation. A raised edge of the tank insure water stays inside the collection region. A small pump with a float switch powered by the solar cells with intermittent pumping forces the water into a pressurized collection pipe system. OR if it is a downhill run we could just let a solenoid open a valve and let gravity do the rest- and in proper geography, this is entirely practical. Pity so much of Florida is flat as a pancake, but parts DO have gently rolling hills. There are several ways to arrange these features, but I personally like stacking everything onto a strong central stalk. Given the height and wind-load carried by local tall power poles made entirely of galvanized steel formed into octagonal tapered poles, I wager this is not a big engineering challenge. The REAL challenge is the refrigeration technology; the solar cell tech already exists.

So we have a tall structure, wider at the bottom, with the top of it black, and the bottom shiny stainless steel, with a tank under it, sitting bolted down onto a solid concrete pad, with a pipe diving into the ground, and 3 BIG dark solar electric panels bolted onto the south facing of it- Aussi's, please turn the dang thing around to face north, ok?

So we need an efficient heat pump with very low maintenance, inexpensive solar cell panels (which is FINALLY becoming possible and practical) and a big pile of stainless steel or aluminum stacked up and welded together, possibly with heat distribution tubes running all through it. And the big bottle neck is THE HEAT PUMP, as solar power is now practical, and of course we can use local domestic power grid power if we like... but at the costs per gallon, we don't like. the trick is to make lots of water ECONOMICALLY.

We need to calculate the amount of cost per 1000 Ltrs or water produced, service life, maintenance costs, yaddayaddayadda... and there are as of now SO many imponderables, that all we can do is take a stab at making one and then measure the living Buh-Jesus out of it, and see if anyone is interested in purchasing acre-feet of water at that cost. When they get desperate enough, they will. Unless desalination beats them to it. So far, Desal is rather expensive.

Solid state refrigeration is better at grabbing and delivering heat than it is at grabbing and removing it, thereby delivering COLD so to speak, but the magnetic refrigeration effect which is still being developed looks like a BIG winner, when it becomes available outside the exotic materials lab. And then there's the ever advancing world of mechanical refrigeration; they may surprise us yet. I welcome discussion and would love to hear about any tech breakthroughs that might bear on this concept.

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