Lets say I built a tower 500 feet tall (more or less a pipe) with an inner radius of Y (Y being an area that could represent an area of air mass as needed or as a volume of airmass.

Allowing that it is open at the top and the bottom for the movement of air (circulation of fresh and old air out of the system) to movement of any air can be either up or down the shaft.

Running a cooling system at the top to reduce the temperature of the air at the top cooling air either to X temperature or X temperature per time, how fast would the air "drop" from cooling and what would be its energy/wind speed?


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In case you need to know. I recently heard of a system whereby colder deep seawater is pumped up. The temperature difference between that cold water and air would cause condensation along any pipe and would cool the air (much like a glass of ice water on a warm summer day). I am theorizing of a system where that water would be pumped up to a height (say 500 feet) into a collection of smaller pipes in a dome shape, moving through those pipes to cause condensation for fresh water which would run down the framework of the dome into a collection tray which would then run to a holding tank. It should cool the air a bit causing it to fall. The desire to collect fresh water at a height is so it could be stored in a gravity system without extra pumping.

I'm assuming that the process of cooling the air would cause air to move about, namely down and that moving air could be utilized in other ways, such as cooling a space or even turning fans on a windmill generator set up. However I do not know how to calculate how much cooling of a mass of air must take place to result in wind speed.

Nobody, any body, somebody???

I can't give you any figures, David, but the cost of pumping water up 500 feet alone might be more than the cost of running an air conditioner.

Another way to cool the air, one that is much cheaper than what you suggest, is simply a long duct running under the ground at about a 5' depth. Drawing air in near ground level (under trees or bushes), and then allowing the ground temperature to cool the air along the length of the duct would give you an unlimited supply of air near 65°F. You could draw the air into a basement and circulate it throughout the house, or, by insulating ductwork, bring it into the house at the top, and allow gravity to circulate the air downward. Your only continuing cost would be the cost or running a good sized intake fan. (Naturally, there are more details than I mention here, but I'm sure you understand the basic idea.) Your initial cost for this would also be significantly less than what you are suggesting.

If I remember correctly, Thomas Jefferson built his house over a cave and used the cool air from the cave to cool his house.

The earth duct could also help out in the winter if it was deep enough. The cold air would be warmed as it travels through the duct, and the burden of warming the air would be less on a furnace.

Both for heating and cooling, this method also also fresh air to be brought into the house.

I am no mechanical engineer but here are the problems to look at first:

You need to consider the delta of temperatures involved and The heat gain or cooling loss of the space and it is critical to examine the actual dimensions rather than theoreticals.

The idea that a tower 500' tall could be cooled by a coil at the top of the tower alone is flawed. "Stack effect" is the natural tendency for air to flow up a shaft or tall space. You need to distribute the cooling evenly to achieve the best results.

You are looking at evaporative cooling systems. Using a mechanism similar to a glass sweating or the human body sweating is how many passive cooling systems work.

I think the issue is that it is generally difficult and expensive to cool but cheap to blow. Cooling is made more efficient by increasing air exchanges. You have to consider heat gain of a space and then consider than you'd have to increase the delta of your cold air considerably to get the desired results without mechanical fans (passive or electric) and you could easily reduce the delta between your cold source and the volume to be cooled by introducing mechanical venting to assist the flow.

Check out the chimney effect or stack effect... cold air does sink but sometimes natural convection fights this. A tall space would not behave as you might expect just thinking in terms of simple physics - convection complicates it all a bit.

Hope something here helps... this is not my strongest suit but since I work on high rises I do see how air flows and we most assuredly could never cool from top down without very powerful blowers.

Cooling towers used in the southwest are a good thing to google - deep shafts allow cold air from the bottom to flow up and in general openings off the shaft will assist in passively cooling spaces around.

Thanks

You have seen my page: [URL=http://wraithwynd.googlepages.com/oceanicprojectentry ]Oceanic Project[/URL]

The power and fresh water supply will be from Ocean Thermal Energy Conversion. Now I know that in Hawaii they have had great success in "sweating" fresh water out of the air - using condensation off of pipes of cold sea water. From what I have read the pipe is a loop - meaning it goes from the deep sea, up to the land then dumps back into the sea. Any pumping energy is reduced due to the siphon effect.

I'm thinking along the lines of a stack with about three corridors radiating on the horizontal at the bottom with open ends - air comes in through the top, cools as it descends, flowing horizontally at the bottom coming out away from the stack. I assumed that the cooler air would remain close to the ground as it moved away "cooling" the local area a bit before heating back up and rising. In this way moving "fresh" humid warm air in through the top and pushing the cooler - "drier" air away.

I was hoping to find some numbers or math or examples out there which would help me to flesh out the idea and figure out the details. 500' is just a number I tossed out there. If shorter means more down draft then shorter it would be. If a 'dome' of pipes at the top would not work and pipes down the length would work better, so be it. I'm trying to figure out if the idea would work or what steps would need to be taken to make the idea work.