YayItGoBoom!
February 23rd, 2004, 04:42 PM
My friend came up with an interesting challenge for us to try: construct a device, similar to the ones used in commercial industry, that is capable of condensing CO2 and ultimately LOX out of air. Theoretically, it is doable.
The aparatus is set up something like this. There is a main cylinder of aluminum pipe, probably 2-3 inches diameter and 5 feet long. Both ends are sealed with endcaps and tapped. 1/4 inch thread for the air compressor (Sears tire pump 130 psi - I don't think this will cut it but its all I have for the time being. The critical pressure of oxygen is 700 psi, but I am not sure if that matters if you can get it cold enough). An exhaust valve will protrude out of the bottom to drain the liquid, and another valve at the opposite end of the pipe will exhaust air into four copper tubes (1/8-1/4 inch) that will spiral around the cylinder. Around this is an auxillary cooling system (probably going to be ripped out of an old freezer or AC unit). The whole thing will probably be submerged in some sort of coolant to retain the cold during pressurization (water would be nice because of its high specific heat, but it freezes, and freon isn't available).
The whole idea is based on PV = nRT. When the cylinder is pressurized, the temperature is increased. The latent heat is taken away by the cooling system. At first, the air will be no where near cold enough to condense the gasses we want, so it will be discharged. As it exhausts through the spiral coils, it 1) loses temperature due to the pressure drop 2) carries away even more latent heat 3) finally, I might just rout it to exhaust over the heat exchange pipes of the refrigerant system, as so to carry away heat from the high pressure coolant (if not it will provide a nice cool breeze :p ).
Once we get in the range of the pressure/temperature to condense CO2, the compressor will run, continually pressurizing as the CO2 condenses and the pressure drops, all the while the coolant keeps the whole thing cool.
Then, if we're lucky, condense the oxygen. And if we get liquid nitrogen, well, I'll just have a headstart on the patents. ;)
Before we make our trip to Home Despot (typo intentional), I would like some advice from people who have just a bit more experience with cryogenics than me. Firstly, what coolant would be suitable? I believe the boiling point of oxygen is less than 100 K.
Second, would exhausting the pressurized gas inside the cylinder do enough to actaully make a difference in getting the temperature down in the first place? Would a refridgeration coil alone be sufficient?
Thirdly, what would be the best kind of insulation to use? Something tells me that Pink Panther fiberglass isn't going to cut it.
Thanks a lot for your imput, please no flames, yes I already know its going to be difficult, but I want to try it.
The aparatus is set up something like this. There is a main cylinder of aluminum pipe, probably 2-3 inches diameter and 5 feet long. Both ends are sealed with endcaps and tapped. 1/4 inch thread for the air compressor (Sears tire pump 130 psi - I don't think this will cut it but its all I have for the time being. The critical pressure of oxygen is 700 psi, but I am not sure if that matters if you can get it cold enough). An exhaust valve will protrude out of the bottom to drain the liquid, and another valve at the opposite end of the pipe will exhaust air into four copper tubes (1/8-1/4 inch) that will spiral around the cylinder. Around this is an auxillary cooling system (probably going to be ripped out of an old freezer or AC unit). The whole thing will probably be submerged in some sort of coolant to retain the cold during pressurization (water would be nice because of its high specific heat, but it freezes, and freon isn't available).
The whole idea is based on PV = nRT. When the cylinder is pressurized, the temperature is increased. The latent heat is taken away by the cooling system. At first, the air will be no where near cold enough to condense the gasses we want, so it will be discharged. As it exhausts through the spiral coils, it 1) loses temperature due to the pressure drop 2) carries away even more latent heat 3) finally, I might just rout it to exhaust over the heat exchange pipes of the refrigerant system, as so to carry away heat from the high pressure coolant (if not it will provide a nice cool breeze :p ).
Once we get in the range of the pressure/temperature to condense CO2, the compressor will run, continually pressurizing as the CO2 condenses and the pressure drops, all the while the coolant keeps the whole thing cool.
Then, if we're lucky, condense the oxygen. And if we get liquid nitrogen, well, I'll just have a headstart on the patents. ;)
Before we make our trip to Home Despot (typo intentional), I would like some advice from people who have just a bit more experience with cryogenics than me. Firstly, what coolant would be suitable? I believe the boiling point of oxygen is less than 100 K.
Second, would exhausting the pressurized gas inside the cylinder do enough to actaully make a difference in getting the temperature down in the first place? Would a refridgeration coil alone be sufficient?
Thirdly, what would be the best kind of insulation to use? Something tells me that Pink Panther fiberglass isn't going to cut it.
Thanks a lot for your imput, please no flames, yes I already know its going to be difficult, but I want to try it.