I've never had any experience with the things.
I reckon they're not wide-spread because they're probably not very efficient for larger applications. (Probably quite noisy too?)
I suspect they need too much energy consumed to produce a reasonable return on coolth gained.~
CO2 collects down in mine shafts from weight? I really don't know, to be honest. I don't think it's so much a case of CO2 getting into mines from the top as it is from it coming in from the deep. There's a lot of CO2 in the bowels of the earth.
The interesting thing is that if you put a CO2 generator into an aquarium half -which is just simply sticking a dish of baking soda in the bottom and adding vinegar, the CO2 gas coming off it .......
WILL displace all of the air in the compartment! So, like, it DOESN'T shoot up and out while the air stays inside; it spreads out laterally and rests on the bottom and rises upward, pushing lighter air out of the top ... until the volume is as much as the tank holding it. (You can check to find out if the compartment is filled right to the top with CO2 by lowering a lit match into the tank. Once it goes out as soon as it's below the edge of the aquarium walls, you know the tank has no more air inside of that compartment.)
To me, this is rather puzzling because on one hand, CO2 and air mix homogeneously if the divider wall is taken out between 2 halves of the aquarium, when one half contains air and the other half contains pure CO2 gas. They will NEVER separate into layers after mixing together, if left alone.
Yet, on the OTHER hand, if you "pour" CO2 gas into the tank containing air, the CO2 WILL push all of the air out of the tank upwards because it's heavier than air and it won't "evaporate" from the tank compartment either ... because it's HEAVIER than air! I'm not really sure why there's that difference.
As per using straight air for air conditioning; yes, it's possible to do that all right but it's not very practical. As you've probably noticed, if you release air from a compressor tank through a nozzle (as in a shop, blowing dust off of stuff), the air coming out is very cold. That's because it's decompressing. On the other hand, a compressor working to
fill the tank ... gets really hot.
So, if you were to use a very large compressor and run the air straight from the compressor through a radiator core outside of your house (to cool it back to ambient or outside air temperature before it goes into the tank), and compress the air in the tank to about 150 ppsi (making 10 atmospheres) .... and then let the air from the tank gradually escape into your house ... the air coming out of the tank would COOL DOWN from expanding and provide you with air conditioning! However, you would need a very BIG compressor and the air escaping would be very annoyingly loud with its hiss.
That's how a refrigeration or air conditioning unit works though, except that a gas is compressed to a certain point and then it "folds" itself (or converts) into a liquid. Since liquid is so EXTREMELY reduced in size from its gas counterpart, such a liquid will hold an enormous amount of heat and save a lot of energy you would otherwise have to expend on reducing the volume of a straight gas by compressing the heck out of it.
There's a really interesting way of using water for air conditioning too. Water, as you know, won't boil unless it's around 200 degrees F. But that's at sea level with 14.7 ppsi. (equating to 0 inches of mercury). If you put water into a closed loop and then suck out all the air so that the pressure is reduced, you can make the water boil at a very low temperature.
http://www.engineersedge.com/h2o_boil_pressure.htm
Looking at the chart above, you can see that if you reduce the pressure to 29.74 inches of mercury, vacuum, water WILL boil at 32 degrees F! That's right around the freezing mark! (Ever hear of "freeze drying"?)
Well, you don't want to go quite that low in temp or you'll have icing problems but ...... you CAN run at around 40 degrees or so at about 29.7 hg vacuum.
Ok, so what you would do then, is have a "compressor" in this closed loop which would create vacuum on one side and "pressure" on the other side. The pressure side would simply bring it up to 0 in. of mercury (or 14.7 ppsi) .... same as the outside air. This side would turn water vapor into water ....... making it very hot by reduction of volume. This hot water would be passed through a radiator OUTside of the house to cool it down to ambient outside air temperature and then fall into a holding tank out there.
You have a small valve and a capillary tube from this holding tank which squirts this same water into ANOTHER radiator INSIDE of your house and rapidly evaporates it into water vapor inside of the core of this inside-house radiator (because it's under high vacuum, being on the suction side of the compressor). In doing so, the volume of the water expands dramatically inside of the "evaporator" chamber (the inside radiator) and ................. DROPS TEMPERATURE instantly to about 40 degrees as it "boils" from liquid into "steam" (water vapor). You extract the "coolth" from the radiator with the aid of a fan. Once the evaporated water has passed through the inside-house radiator, the compressor turns it back into water (which is really hot) and the hot water goes back through the outside radiator and cools down ........ and repeats the loop.
This is exactly what is done in a regular refrigeration unit. The coolant is simply a liquid/gas that changes state somewhere around the freezing point. Freon was super for that but freon has been outlawed.
I'm not sure why water fridges aren't used much. Maybe it's a problem of keeping everything sealed under very high vacuum or maybe it's icing problems or rust. I do know that they are sometimes used in boiler systems ...... with the boiler turned off for the summer (of course). That way the system works double duty: heat in winter/cooling in summer.
-Vince
