### atmospheric water condenser (as water source)

greenspun.com : LUSENET : Countryside : One Thread

I was recently offered a very afforable piece of property located in a mountain area that noone has been successful drilling a well. A friend from South America stated that in his country people would place a bath tub filled with dark, fist size stones; add a pipe and spigot to the drain so that moisture would accumulate and give them their daily supply of drinking water. Anybody got info or know how much water would accumulate in 30 to 50 % humidity?

-- mitch hearn (moopups1@aol.com), April 09, 2001

#### Response to atmospheric water condenser

Mitch,

The moisture in the air is determined by a property called specific humidity. It can be deterimined by measuring the dry bulb and wet bulb temperature of the air and plotting it on a psychrometric chart. For example, 75 degree air at 40% Rh contains approx. 50 grains of moisture per pound of air. One pound of air is approximately 14 cubic feet. If you had a small fan, approx. 100 cfm(cubic ft per minute), and you were able to condense say half the water out of the air stream, that would be about 25 grains per minute or just a little over 2 lbs in 10 hours.(7000/grains/pound) If its a little warmer and a little more humid you can get a lot more water but at 30-50% rh you don't have a lot to work with. As air gets warmer its ability to hold moisture increases. Relative humidity is the amount of moisture in the air relative to the maximum amount of moisture the air can hold at that temperature. This means there's a lot more moisture in say 90 degree air at 50% rh than 75 degree air at 50% rh. I hope this makes sense, psychrometrics is the science of the properties of air and it can get a bit complicated. Good luck.

CQ

-- Carter Quillen (chucky@usit.net), April 09, 2001.

#### Response to atmospheric water condenser

mitch, look in the archives as this was discussed a couple of months ago. I can not recall the details, maybe someone else will recall. A similar concept is used in South Africa and Saudi Arabia; both desert regions near sea water. It sounds like with your humidity it should work for you also. It is also a function of the temperature of your condenser. Think of a cold glass of iced tea an a warm humid day and the water droplets on the outside of the glass - same concept.

-- Lynn Goltz (lynngoltz@aol.com), April 09, 2001.

Seems to me a solar condenser would work better. I have never actually tried, but have been told that the following idea works.. it could easily and cheaply be expanded upon. If you were, lets say, lost in the desert with a sheet of plastic, you could dig a hole in the ground, chuck some mushed and broken pieces of cactus in, cover the hole with plastic. The sunlight would cause the moisture to become airborne and stick to plastic. A dimple in the middle with a container beneath would allow condensation to drip into (kinda cone shape the plastic). I would image that dew would also form on the plastic at night.

-- -Kevin in NC (vantravlrs@aol.com), April 11, 2001.

As I recall, meteorologists term 60% relative humidity and less as 'dry air' I imagine it will be quite a challenge to extract useful amounts of water from 30 - 50% humidity.

-- john hill (john@cnd.co.nz), April 11, 2001.

Keven, you would die of thirst in the desert waiting for that system to work. A best you can get maybe a half pint per still. Sounds like a good idea, but in actual practice not quite like advertised. The idea is perpetuated by survival types that have not tried living on the water it produces.

-- Lynn Goltz (lynngoltz@aol.com), April 11, 2001.

Moderation questions? read the FAQ