"new" aircooling system

Hey guys,

just found a real humdinger of a cooling device. I was reading through an old Popular Science magazine, July 1969 and came across an article entitled "Hot and Cold running air" that had some drawings and description of a sort of separator turbine that splits a stream of air into hot and cold components, broad differentials of 40C or more are claimed. It is claimed to be more efficient than a Ranque Hilsch vortex tube and looks to me like it could possibly be run off something like a furnace blower or centrifugal compressor rather than needing a high volume, high pressure compressor.

The inventor was/is Prof. J. V. Foa, the patent number is 3,361,336 and is viewable as a tiff image (browser plugin required) at www.uspto.gov The patent of course is damn hard to read and calls the device an "energy seperator" but I figure the more technically minded guys here might get something out of it. The Popular Science article is a hell of a lot clearer. Don't know if the patent is still good, it was granted in 1968, no expiration data online, you have to phone for it. Anyway, the inventor built a model in his home workshop and got some pretty promising results from it, so it's probably not beyond a skilled amateur to "knock one together"

Not sure it's mentioned in the patent clearly, but the key to understanding the operation of the device is a phenomenon whereby a jet of air at an oblique angle to a surface, will separate into warmer and colder streams.

Anyway, I don't figure it's some kooky patent because this Foa guy has a heck of a lot of patents pertaining to airflow, turbines, jet engines and was/is an aeronautical engineer.
I have a feeling that this principle will work well with water also and may actually have been simultaneously invented in a slightly different form as a high efficiency energy exchanger for water heating, that hasn't had it's cold end tapped. This form has been the subject of debate over the last decade or so, not many people want anything to do with it because it apparently demonstrates over unity efficiency (Which it would do if no-one realised it was working as a seperator) There are similarities that strike me in the design of examples of this device that I have seen and the one patented by Foa.
So, hope someone finds this interesting info, I sure did, and I'm going to be collecting up some coffee cans and blowers etc to experiment with. I figure a 2lb coffee can sized unit driven by a blower about half the size of a furnace unit would be capable of delivering 10C air in sufficient quantity to cool a regular sized case down to an internal ambient of just a degree or so above that. Of course you might want to exhaust the hot output outside.

have fun,

Road Warrior

wow, if this device is used, we can have pure hot air coming out of the case and cold air being recirculted around the case, if there is any more info on it i would like to know

I remember years ago Edmund Scientific used to have an item in their catalogue that did this. It was a glass tube in the shape of a T. You would blow into one end and you'd get cold air out one end and hot air out the other. I didn't get any, but wish I had.

Since I started ocing, I've been looking for this device (for obvious reasons ) with no luck. Edmund doesn't carry it anymore, which leads me to believe that it didn't really work as advertised. But if it does, it would be great for cooling your case. Just attach a whold bunch of these together, put a nice big fan blowing in and put the cold end into your comp. Instant AC for the PC

Okay, I picked up the web by it's ankles, shook it silly, and nothing fell out. Can't find any further info on professor Foa or his device. It's only because I thought of looking for the patent I could find anything at all. There's a hell of a lot of stuff around on Ranque Hilsch vortex tubes now though, heh, there's about half a dozen eastern european "scientists" claiming to have invented them and have patents in their respective countries, which they say should be internationally recognised. I was researching these tubes in '95 at university and had references from 1936 to the 50s and 60s, so I really doubt they have anything fundamentally different enough for a patent to really stick.

Anyhoo. It's real tough to find anything on this out there.

there has been discussion of a device like this _HERE_ during the past month or so, somebody said they are used in some industry halls&etc where noise obviously doesnt matter.

they do need tho continious air pressure and are noisy. (and compressors are noisy too generally, some expensive one's dont make much noise tho)

and i'd also bet that it could end up being much cheaper to use 'regular' cold devices.

Yeah the Ranque Hilsch type vortex tube has been discussed here, however as far as I am aware this Foa device is significantly different and has not been discussed.

Points that separate the Foa device from the Ranque Hilsch tubes.

*claimed greater efficiency
*different principle
*lower pressure air required.
*moving parts in the device instead of a static vortex chamber.
*Could be run off a centrifugal blower/compressor (Basically a blower with longer impeller blades/larger disk and a more resticted output)
*more suited to high volume applications
*no high pressure whistle, probably some turbine or fan whine but should still be better than the screaching demon vortex tube.
*Ranque Hilsch tube known to be used in industry, however I know no application of the Foa device.

Possibly the patent rights were taken up by the military from Foa, which is why there is little discussion of the device online today. It is also possible that the device has found a specialised niche in aircraft airconditioning systems an application which Foa himself supported and is little known outside that field.

Road Warrior