nisey79

Mon, 28 Nov 2005 11:18:38 -0500

Steam can be used for air conditioning with a steam jet cooler, which uses water as a refrigerant. The water is vaporized at a low temp. in a vacuum induced by a jet of superheated steam.

scott

Mon, 28 Nov 2005 11:04:19 -0500

I may be able to offer some infor about steam for airconditioning. I studied Mechanical Engineering as an undergrad before I fled to art school in Britain, and spent some time working the HVAC field. So, I hope what I say makes sense, I am a bit rusty. The refridgeration/air conditioning cycle usually consists of 4 devices: compressor, heating coils (and fan), turbine or expansion valve, and a coiling coil (with fan). The process is pretty simple, a reridgerant like R134a, or R14 or R12 (Freon, which is no longer used) is used, in gas form. The gas is compressed, then heats up dramatically as the pressure drops, then undergoes further expansion or a drop in entropy - causing a drastic drop in heat, and the cycle repeats with the cool, and low pressured gas returning to the compressor. Power plants and heat pumps work on this same process, only they work in reverse. Power plants usually use a boiler to heat water and then use steam. Here, pumps are used instead of compressors because compressors imply gas only, and pumps are used for liquid only. In the case of steam, I imagine that Con Ed could be used in place of a local compressor and radiator fan components, so an air-conditioning system could be set up using steam as refridgerant and most likely a thermo-expansion valve (TXV) and whatever type of cooling fan to distribute the air. Does that make sense? I have to say, a good source of info for this would be howstuffworks.com, although they only speak about air conditioning and not so much about thermodynamics, power plants. To learn more about thermodynamics relevant to this issue, try to look up: Canot Cycle, Diesel Cycle, Otto Cycle, Rankine Cycle. I found a simplified diagram that shows the case well. http://static.howstuffworks.com/gif/ac-cycle.gif Here, the red heating coils and the compressor would be Con Ed's responsibility, with the expansion valve and blue cooling coils being installed locally. Also, I don't know if the loop would 'complete' itself because most likely the steam is discharged into the water supply as opposed to being piped back to Con Ed. Then again, the steam comes from the city water supply so I guess the cycle does complete. Someone feel free to correct me. Like I said, I am no longer a practicing engineer. Hope this helps.

dan

Mon, 28 Nov 2005 10:59:19 -0500

it's like magic...but a more scientific explanation of ABSORBTIVE REFRIGERATION can be found here: http://geoheat.oit.edu/pdf/tp51.pdf

Gothamist: Superhot Steam!

nisey79

scott

dan