Tom Booth

Are you suggesting then that the bottom intake valve is stronger to compensate for the poor seal around the connecting rod, and that the top has no connecting rod so can make use of a weaker spring. If so, I would say that makes no sense. A stronger spring on the bottom chambers intake would only create more vacuum aggravating the problem of air leakage through the connecting rod packing. I've work as an engine mechanic most of my life. In my experience, check valves using a little ball have very weak springs that can be easily compressed between the fingers. The valve at the top looks exactly like a typical automotive type or internal combustion type valve. Typically these valve springs are so strong a special valve spring compressor tool is required and they can be rather dangerous if they slip out of the valve spring compressor. One could put a hole in the ceiling or put out an eye. If you are saying that a stronger spring is needed at top because this is the main compressor and a better seal is needed to prevent leakage back through the valve. That would make more sense. What I'm generally looking at is references such as: "The throttling of the gas at this stage produces a forced expansion of the gases and condensable vapors, and simultaneously lowers the temperature in proportion thereof. The fall in temperature and pressure causes the entrained vapors to condense to liquid, and collect this condensable matter, the gases are caused to discharge into the separator b through nozzle c." From "Industrial fuels" by Joseph Stephenson pg 33. Or this extract from Wiki: " Helium and hydrogen are two gases whose Joule–Thomson inversion temperatures at a pressure of one atmosphere are very low (e.g., about 51 K (−222 °C) for helium). Thus, helium and hydrogen warm up when expanded at constant enthalpy at typical room temperatures. On the other hand nitrogen and oxygen, the two most abundant gases in air, have inversion temperatures of 621 K (348 °C) and 764 K (491 °C) respectively: these gases can be cooled from room temperature by the Joule–Thomson effect.[1] For an ideal gas, is always equal to zero: ideal gases neither warm nor cool upon being expanded at constant enthalpy." In other words, for an "ideal gas" which is what pv=nrt applies to, there would be no change in temperature from such "throttling" or forced expansion through a valve. Some gases, like helium would actually heat up but regular air being mostly nitrogen and oxygen would be cooled down. I was hoping there might be some way to get an idea how much cooling would be possible, or how much cooling could reasonably be expected, but it seems pv=nrt isn't going to be of any help as air is not an ideal gas. Perhaps there is some other formula or equation that would be applicable from some HVAC manual but I'm guessing that any equation relating strictly to an "Ideal Gas" is going to show no change in temperature.

"Nobody said it was a two stage pump." OK, my mistake. I thought that was what you were implying. Because the valve on the lower left of the bottom part of the cylinder is also a (fresh air) inlet valve. "It may look that way to you, but it doesn't to me." No problem. you may very well be right. I appreciate your input. Thanks! OK, thank you all very much. I'll accept your judgements. What I don't get though is then why this elaborate description of adiabatic cooling on expansion from this website: http://hwstock.org/adiabat.htm And I think I've read other references similar to this over the years. Could it be because Air is not an "Ideal Gas" ?

Really ? I was actually getting that result at one point using an online calculator, but I thought, that couldn't possibly be right. Increasing pressure raises temperature right ? So doing the opposite should result in cooling. Then I was reading how if you have a balloon with air in it and you carry it up a mountain, the balloon will expand and the air inside will cool. Bring it down and the opposite happens. Somehow this just doesn't seem like it could be right. Like a violation of the first law of thermodynamics not right. If I expand a gas to twice the original volume and its stays the same temperature, then what happens when I compress it back down again ? It would get hot right. If I just kept expanding and compressing the same air I could make it as hot as I wanted. BTW, I'm not doubling the volume by adding more air. Just to be absolutely clear on this and make sure we are both thinking in the same terms. What I'm talking about is this. Words can be tricky sometimes. Like by "pressure" I could mean inside pressure or outside. "Volume" could mean amount or size etc. so just to be clear. these are the conditions: The cylinder contains a piston with an air tight seal. No air can get in or out. There is a fixed amount of air in the cylinder. Press down on the handle to raise the piston. If the starting conditions are known, is it impossible to determine the result ? The gas inside the cylinder is 1 atmosphere, (about 14.5 Psig) and 60 F. call it one pint. That is before pushing down on the handle to expand the air to twice the volume. There is no air being added. Just mechanically expanded to increase the volume. Does it really stay the same temperature ? Just double checking. Well, none has been compressed yet in the other half of the cylinder either. There, just check valves are used. The compressor is double acting NOT two stage. That is it compresses air on both the up and down stroke. but always new air. Anyway, this one valve is accessible, The check valves are not. So, it could be made adjustable, or could be replaced. Perhaps the inventor built it that way so he could experiment with different spring strengths or make adjustments while the engine was running.

By "doubling the volume" I'm just adapting an arbitrary scenario. The cylinder holds X volume of air. It admits only 1/2 that potential due to the spring being "medium" strength. Yes that depends on the strength of the spring for sure. However, this is purely hypothetical so I could make the spring tension adjustable and turn the tension wing nut or whatever until that's the way it is. I could increase the tension and then say tripling the volume and work it out from there. In that case the even stronger or tighter valve would only allow 1/3 X into the cylinder. I'm treating this AS - IF the amount of air entering the chamber were controllable and the action of the valves opening and closing were controllable. In that case, you open the valve fully. Draw the piston down 1/2 way then close the valve completely and draw the piston down the rest of the way. Now you have expanded the air to twice the volume. I think it can be assumed that under such hypothetical controlled circumstances, doubling the volume of a gas would halve the pressure. By looking at it. (in the patent drawings above) By comparison, the spring on the inlet valve (#44) is at least 4 times bigger than the springs on the other valves (#43). Bigger does not necessarily mean stronger but I think it's a fairly safe assumption. This is a double acting compressor. The other three valves are all regular "check valves". Check valves are generally designed to offer as little resistance as possible so have very weak springs, just enough to hold the valve closed. In a normal compressor, there would be no need for anything else. The one valve on top however is obviously different. Much bigger with a much larger spring. I think it can be assumed that this one valve serves some special purpose. Of course I can't take it out of the patent drawing and test it to see if it is stronger than the other springs but it sure looks stronger to me judging by what I can see in the drawings. Don't you agree ?

Well, using various online sources / calculators / charts etc. I've come to the conclusion that for Air, there would be a 10 degree F drop in temperature (approximately) for every loss of 1 psi due to expansion (or pressure reduction). Starting at 14.5 psi at sea level (14.6488 - 14.6950 actually, according to different sources). Would not expanding that to twice the volume (whatever the original volume) result in also cutting the pressure in half ? i.e. to about 7 psi ? So expanding air to twice its volume would result in a drop in temperature of about 7 X 10 or 70 degrees F. So starting at 60 degrees Fahrenheit, in the above example, (60 F 1 atm expanded 2X) the resulting temperature would be about -10 Fahrenheit after expansion to double the volume. I'm not arriving at any of this from pv=nrt directly, though some of the sources used it. Rather this is based on pressure changes due to elevation in the atmosphere. As you climb a mountain the pressure drops. About .5 psi per 1000 ft of elevation. (or 1psi per 2000 ft) and according to the sources, a corresponding temperature drop of about 5 F per 1000 ft. Primary source: http://hwstock.org/adiabat.htm also: http://www.unitarium.com/pressure The thing at this point I'm not really sure about is, am I correct in assuming that doubling the volume of a fixed amount of air would halve the pressure ? Seems to follow from basic logic but... Is it necessary to use "absolute pressure" rather than psi ? Is there a difference ? I'm a little fuzzy there. I'm also assuming that pressure and temperature drop due to elevation would correspond to temperature and pressure drop due to mechanical expansion, which may be wrong but I have little else to go by at this point. Anyway, if anyone can come up with a refutation, correction or improvement in regard to these basic conclusions of rough estimates I would certainly appreciate any additional help or insight. Thanks!

Well, that's a good start. It would be nice if it were possible to get some rough idea how much lower the temperature could go. Can we just plug in some arbitrary values? For example, the maximum volume is whatever the cylinder can hold with the piston fully expanded. I'm guessing 1 pint. Start out with 1/2 pint of air in the cylinder (60 F 1 ATM) expand that to double the initial volume.

The piston is being driven by an air motor (external force). No, the piston does not move because of anything that happens in the cylinder. I'm going to say that the pressure before it moves is 1 atm. This is necessarily fudging things but I don't see any other way to proceed. Reasonably, as the piston moves down the pressure drops along with the temperature. No additional air is admitted.

OK, great! What I imagine happens is the piston is at top. No air is in the cylinder. As the piston moves down it creates a vacuum. When the vacuum is strong enough the valve is forced open slightly by atmospheric pressure outside the cylinder and a little air enters providing some relief, then the valve closes again while the piston continues to the bottom. (or the valve remains slightly open till the piston reaches the bottom then closes). I think, effectively, this would be more or less the same as if there was a little air in the cylinder initially, and this small amount of air was then expanded. So I'm going to say 1/2 pint of air is in the cylinder initially, then the piston moves down expanding this 1/2 pint to twice the volume. The 1/2 pint of air is at 60 degrees Fahrenheit temperature and 1 atmosphere pressure. It is then expanded to twice its initial volume.

The patent for the compressor does not say that this valve or cylinder is for cooling. That's just my theory. The patent does say that air in the tank is below freezing. Heaters are used to bring the temperature back up above freezing to drive a compressed air engine. It seems reasonable to assume then that the compressor is delivering below freezing cold air to the tank. Somehow the air is being cooled. It looks to me like this valve that may be restricting air intake may be the source of the extreme cooling. I'm just trying to figure out if I might be on the right track or not with this theory. Could ordinary ambient air be cooled significantly below freezing by drawing it through a tightly closed valve into a cylinder? That's the basic question. Then, if so, how much cooling might actually be possible ? -10, -100, liquefaction ? It seems some similar process is commonly used for liquefaction of gases, refrigeration, cryogenics etc. In other words, looking at this picture: Could the top cylinder be for cooling by "pulling a vacuum", expanding rather than compressing the air. Does this seem like a reasonable hypothesis given the apparent strong spring on the inlet valve? If so, how much cooling might be possible at various different spring strengths? I thought it might be possible to get some idea using the ideal gas law formula but I don't really know how to use it.

Sorry, as I tried to explain, the patent does not provide enough information to give any exact values. Other than; all I know for sure is that there is plain old ambient temperature atmospheric air being drawn into the cylinder, the rest is mostly guesswork or assigning some reasonable arbitrary values. I can say what doesn't change. Assuming 1/2 pint of air enters the chamber (arbitrary), This "amount" (number of air molecules in 1/2 pint of air - moles?) does not change, at least not for the purposes of calculation. Is it at least possible to calculate, or is it already generally known what "amount" of air (moles?) there would be in 1/2 pint of air at ambient temperature (arbitrarily set at 60 degrees F) at ordinary atmospheric pressure ? Since air is being "throttled" or drawn in and expanded simultaneously it is practically impossible to give an actual starting and finishing value as far as "amount". !/2 pint is not really in the cylinder and then expanded to twice the volume. Initially there is nothing in the cylinder. The air is actually drawn in and expanded simultaneously, but to simplify matters it could be said that X amount of air is drawn in and then expanded to twice or three times or whatever the volume, though in a running "compressor" both would be happening simultaneously. Everything else changes. Volume is increased. Pressure and temperature presumably decrease.

I have been looking over a patent for an air compressor (Bob Neal Compressor). Looking at the illustrations and reading the patent it seems apparent that this "compressor" is not so much compressing air as it is cooling it. Theoretically, by cooling the air significantly it will condense or contract, thereby reducing the volume and in this way effecting "compression". At least that is the theory I'm working with at this point. There is, what seems to me, a rather strange valve arrangement for a compressor. Here is a clip of an image from the relevant illustration from the patent itself: The main valve in question (#44 in the illustration at the top of the "compression" cylinder) has no rocker arms or valve lifters to mechanically open the valve. On the contrary it is held closed by, what looks like a rather strong valve spring. This is the air intake. There is also a check valve (#43) for exhaust but this can largely be ignored along with the check valves at the bottom. When the piston (#25) is moving down, it appears that the only way the valve (#44) can open would be by the piston "pulling a vacuum". How much of a vacuum would depend on how strong the spring is (which, unfortunately, is not specified in the patent). The question became, why this apparently strong spring when another simple check valve as on the bottom would due? It appears that the function of this top cylinder chamber is probably cooling by expansion. The piston moves down but the air intake is restricted by the valve spring. The result being, presumably, a certain degree of mechanical expansion of the air that does get through the valve. It can be assumed that the piston is pulling in atmospheric pressure air at ambient temperature. The volume of the chamber into which the air is admitted through the valve is not specified in the patent but we could assign some reasonable arbitrary value. Say, if the valve were missing or "wide open" the piston would draw in 1 pint of air (at one atm ambient temperature) with no resistance. Let's say ambient temperature is 60 degrees Fahrenheit. The air intake is, however, restricted, so I think it can be assumed that something less than 1 pint of air is actually drawn in. The piston however, continues downward, expanding whatever amount of air is admitted to the full 1 pint volume. The actual percentage of the potential 1 pint actually drawn in would depend upon the spring tension. We don't know the spring tension but I think it should be possible to get some rough idea how much COOLING by expansion might be possible with such an arrangement. For example, if just 3/4 pint of 1 atm 60 F air is drawn in and expanded to the full 1pint volume. Or with a stronger spring, if 1/2 pint is drawn in and expanded to the full volume. What would be the resulting temperature if these values are plugged in to pv=nrt ? That is, for the second "strong spring" example, If 1/2 pint of 60 degree ambient atmospheric air is drawn in and expanded to twice its initial volume, what will be the temperature of the gas when the piston reaches the bottom of the cylinder? Do we have enough information? What would be the resulting temperatures for various arbitrary ratios of expansion? (spring strengths or tensions). What would be the temperature reduction ? I've tried to do some calculations using online calculators and am coming up with what seem like ridiculously low temperatures, like -300 degrees F and such, but I find the formula rather confusing and have no confidence that I'm doing it right. Given the above rough figures, starting with ambient air at 1 atm and a potential volume of 1 pint can anyone help me figure out what the resulting temperatures might be after expansion for various arbitrary expansion ratios ? I hope I have made it clear what I'm trying to figure out here. If anyone can help, feel free to use whatever values seem reasonable that will produce some round numbers, I'm just looking to find out what degree of cooling might be possible. Someone is planning to actually reproduce this compressor, but at this point I'm just trying to figure out how much cooling of the air might be possible with such an arrangement.

Introducing the All-In-One Handy-Dandy Vortex Tube: It makes Hot, it makes Cold, it runs a propeller, it even vacuums the floor, Get yours now! Video : Vortex Tube spinning propeller and vacuuming talc (7.06 MB mpg)

Wow, thanks for that article. Why did I not see your post earlier ? Anyway, I found the part about "There was an ear-piercing scream like that of a jet priming for takeoff". I've read of the same thing before in other articles or accounts about the vortex tube - that it makes a horrific noise. My tube seems to be working a little, just warm and cold rather than very hot and very cold, but it wasn't working at all before I shortened the length of the hot tube some. But it really isn't making any sound at all, just the rather quiet hiss of air. I also appreciated the cut-away view of the inside. I read elsewhere that some tubes are tapered inside. I wouldn't think so, but I didn't seem to be getting any response from the thing at all until I shortened the length of the Hot tube, though, it is hard to say with just one or two trials. The capillary tubing might have been plugged with something and then it blew out later, I can't really be sure without building another one. I'm going to try making some out of PVC pipe as some have said it works better than metal and it is also cheaper and easier to work with, unfortunately it is also bigger in diameter and will require more air. There is only a vacuum at the cold end when the plug is taken out of the hot end. I read a forum recently where someone else reported the same thing when the plug was off the hot tube. Well, actually to quote: and another: So, can't really be sure but this doesn't seem to be at all unique to the one I made. The hot end is supposed to have a valve of one sort or another to control the air flow. Usually a tapered plug like a cork in a bottle that just lets (Hot) air escape around the edges and is supposed to cause the cold air in the center to return back in the other direction. I'm skeptical that that is the exact mechanism of operation, especially since seeing some thermal images of one in operation. In the thermal imagery I see no signs of any center COLD core inside the Hot tube. The heat seems to be emanating directly from the center orifice, which would seem to lend some support to my theory that this is where the actual hot/cold separation is happening: Scroll down a way on this page for the thermal image: http://ottobelden.blogspot.com/2011/06/homemade-ranque-hilsch-vortex-cooling.html It just looks Hot on the hot side, getting hotter towards the end and cold on the cold side, divided right at the "diaphragm" or orifice in the center. There doesn't seem to be any indication of a reverse cold vortex as far as I can see in the thermal images. (There are more thermal images in his YouTube video but they look just the same.) Usually the thing is said to have "no moving parts" though one guy on that other forum reported that some old vortex tubes did have something spinning at the end of the hot tube, though I have never seen this. I noticed that the tubing I used from the air-conditioner (after I cut some open) has a kind of stamped pattern of some sort on the inner surface that looks like a cloth weave. What the purpose of that might be I'm not sure, perhaps to increase turbulence for heat exchange. Probably not a good thing in this particular application. Since this tube isn't making any dangerous levels of heat or cold I was able to test it out by putting one end against my lip. In fact I let the cold end suction my lower lip into it, then I adjusted the valve at the hot end. At the point where the suction began to let go and the cold air began flowing out the cold end I could definitely feel a kind of pulsation or vibration like a vibrating reed. With further adjustment of the valve and a greater flow of cold it was more difficult to detect but I suspect it was still present to some degree, It faded out gradually as I adjusted the valve further. Nothing except for the "diaphragm" or orifice between the hot and cold sides. Otherwise it is just a straight tube It is a small copper washer that I ground down around the edges to fit inside the tube and soldered in place. Nothing other than the Hot end has the air jets going into it, just to the side of the diaphragm from the capillary tubing and the hot tube is longer, otherwise it is just one long tube divided into two by a "washer" with a hole in the middle. And also the hot end is plugged by a "valve". I just used a bolt with the end ground down to a taper, though I tried a number of other things. One thing I noticed that makes me suspect of the predominant theory is that it seemed to work just as well if the hot end was just plugged up with something porous like a wad of steel wool or even a fish tank aerator (or just my finger) or practically anything. In other words, as far as I could tell it did not seem to be a matter of letting the Hot air escape around the perimeter of the tube but rather just a matter of restricting the air flow out of the hot tube irregardless of how that was accomplished, which seems to contradict the conventional theory of operation. But then, this tube isn't exactly working up to par either. Apparently the size of the hole in the "washer" or "diaphragm" needs to be in proportion with the other dimensions Pipe ID, length, and the ID of the capillary tubes I'm using for "injectors" instead of just drilling holes as is usually the case. I'm thinking though that material is a consideration. Old diagrams seem to illustrate the use of what looks like steel pipe. I'm not sure copper tubing was available when this thing was invented. Copper pipe had different thermal characteristics. It conducts heat much better than steel so there may need to be some compensation for that, though its difficult to guess what modifications might be necessary without really knowing how the thing works. I'm guessing that the copper tube would need to be shortened from the length specified for steel pipe. I'll be doing some additional experimenting and hopefully have more definite information soon. An interesting note about the Popular Science instructions: A plastic, "fiber" or even a wooden diaphragm, washer or "throttle" is specified, though the rest of the thing can be built from brass. This seems to be further confirmation, IMO, that the critical point of heat separation is taking place at the "throttle" or central orifice or "diaphragm" or "washer" as it is variously called. What other reason could there be for this specification other than to prevent heat conduction at that particular point where the heat separation is actually taking place. It doesn't make sense to me that hot and cold air are separated in the Hot tube by the vortex. IMO this would just tend to push ALL the air to the walls of the tube and leave a partial vacuum in the middle which I think is the reason for the suction when the hot tube is not partially blocked with a valve. I think the conflict between the sucking action of the "venturi effect" and the back pressure from the hot end being plugged causes some kind of rapid fluctuation or back and forth impulse through the "throttle" in the middle setting up compression/heat waves that due to the precise "acoustic" dimensions of the tube become "standing waves". But, that is just my pet theory at this point, mostly, though I think the thermal images and some other evidence like the necessity for a plastic or wooden, non-heat conducting washer and general principles. I don't know as there is any evidence to support the idea that a vortex of any sort can separate hot and cold air molecules whereas it is commonly available knowledge that "sound" waves cause compression which causes bands of hot compressed air. Perhaps these bands are separated due to the above described oscillation at the "throttle". This would put this in the same category as a thermal acoustic engine I think. BTW. If you are interested in seeing what's inside the tube, I have some photos I posted earlier in the other thread where I got interested in the Vortex Tube here: http://www.scienceforums.net/topic/46143-stirling-turbine/page__view__findpost__p__623450 As can be seen here, there is nothing particularly interesting inside the tube other than light coming in through the other end: Oh, another BTW. I'm still not sure what caused the drill bit I dropped into the vortex tube to start spinning faster. (judging by the sound it made) when I held some steel wool around the hot tube attempting to dissipate heat. When I wraped the same steel wool around the tube and held it in place with tape (instead of my hand) I could not get any such effect. I'm thinking that if anything, the steel wool was making the tube warmer or preventing it from getting colder as the shop was rather cool. In other words I was holding the steel wool in my hand which was of course at my body temperature more or less (probably a little less) but this would have been warmer than the air in the shop at the time so in effect, I was not dissipating heat with the steel wool but more than likely adding heat or preventing heat loss by applying the steel wool which was warmed by holding it in my hand. So now I'm thinking that the vortex was strengthened by REDUCING heat dissipation rather than by increasing it. This would make more sense as some say it is easier to get a working vortex tube by making it out of non-heat dissipating material like PVC pipe instead of metal. When I was holding the steel wool to the pipe with my hand it was effectively adding my body heat, but when I just taped it in place this was not the case and it had no effect. Perhaps I should try applying the heat from a candle flame or a torch and see what effect that has. I made a kind of wooden pinwheel I could insert down into the tube to experiment with that shouldn't cause any damage. It is a wooden dowel with a propeller on the end to more easily see it spinning and there is an adjustable stop to keep it from going too far down into the tube.

Cool, and very interesting, I'd like to see one of these things and maybe see if it is made in a similar way or what exactly. This sounds kind of like what Airplanes still use for cabin cooling using ram air through an "air-cycle" cooling system while in flight, but those systems are huge. Something you can clip on your car window ? I'd like to see that. Anyway, I came here today to mention that I did the modifications on the tube mentioned previously. Removed and pinched off the top of the handle, added stainless steel padding to the hot tube and whatnot. I also made a "stop-cock" that could be very finely adjusted. None of these changes made much if any real difference. I think I just found out why in reviewing some additional online information last night: ----------------clip: Now you tell me! (The above link is very informative by the way, with some interesting thermal images of the vortex tube.) Of all metals; copper is one of the best heat conductors, aside from silver and gold. By thermometer reading I was only able to get a temperature drop of about 15 degrees Fahrenheit at best. By comparison, I got about 5 degrees or so LOWER than that just blowing air onto the thermometer straight out of the compressor hose nozzle! But, on the other hand, that was a very large VOLUME of air that does not produce heat and cold simultaneously. I have noticed that it seems like all the commercial models have some sort of plastic or Bakelite type inserts for the diaphragm section with the spinner groves and orifice, even if the rest, the tubes themselves and the housing are metal. This again seems to suggest that the critical heat separation is taking place at the central orifice and not in the tubes or these commercial units with metal tubes with a plastic central insert would probably work no better than my metal model. My central orifice is made out of a solid copper washer in a copper housing soldered to copper tubing - no wonder it is barely working. Well, live and learn. I will still make some videos when I get the chance as this tube IS CREATING A VORTEX, though apparently the heat/cold generated is being lost or re-equalized as quickly as it is produced due to the high rate of conduction through the copper. And thanks for the information about the Vortex car air-conditioner. I will be seeing if I can find out any more about it. Tom

I was about to head out to the shop this morning (with a cup of coffee to make some modifications to the small vortex tube as discussed earlier. Probably start by cutting off the top of the "handle" and replacing it with something non-heat conducting, like wood,) when a new theory occurred to me that I thought I would share. I got a clue from the vacuum effect on the cold tube when the stop was off the end of the hot tube. It appears that there is something like a "venturi effect" going on. Air gets thrown to the perimeter of the tube and due to its high speed of rotation cannot exit through the orifice in the diaphragm but goes the other way towards the exit at the other end (Hot or long end) of the tube leaving a vacuum in the middle. The vacuum is sucking air through the orifice from the cold end of the tube (or at least trying to). This is not particularly unusual. Many IC engine carburetors utilize the venturi effect to deliver fuel to the carburetor. But when the end of the Hot tube is blocked the air trying to rush out is bounced back creating a kind of concussion wave that travels back towards the diaphragm. The "Back Pressure" or reverse wave collides with the air being drawn in through the orifice due to the venturi effect. This sets up a kind of back and forth reverberation at the orifice between the two tubes So I'm guessing that there is some sort of "standing wave" situation which accounts for the acoustical-like dimensionality requirements but this is, strictly speaking, I think, more on the order of a concussion wave, shock wave or pressure wave rather than a "sound" wave. By adjusting the valve at the end of the Hot tube it is possible to cause a kind of conflict of interests at the diaphragm orifice where the air is alternately sucked through one way due to the venturi effect and then pushed back due to the rebounding concussion wave from the stop or plug at the other "Hot" end. This sets up a reverberation which is amplified due to the tubes precise acoustical dimensions which creates a kind of pressure or concussive standing wave. I'm thinking that the usual vortex theory is somewhat incomplete, or at least, I'm speculating that the temperature difference is not a result of heat transfer between an internal and external vortex. Maybe it is, I don't know, but my new theory is that the real action is all taking place at the diaphragm orifice. Lets say that there is a standing wave due to the reverberation. The air is traveling through the diaphragm orifice, first one way then the other. If this reversal were in step with the standing wave, say the direction reverses every 1/2 cycle of the wave the pressure/temperature would reverse as well. In other words, each time the air flows one way through the orifice a small pocket of cold air would be delivered through the orifice then there would be a reversal and a small pocket of compressed hot air would be delivered through the orifice in the opposite direction. With every reversal of direction in air flow there would be a corresponding reversal in temperature on one side or the other of the diaphragm opening. In other words there would be a kind of Doppler effect or something where there would be a tendency for the air going left through the orifice to be compressed/heated and to the right expanded/cooled repeatedly in rapid succession but with relatively little actual air flow in either direction so that that the difference in temperature would tend to be cumulative. As left to itself, the air would be suctioned in through the "cold" end and ejected out the "Hot" end, there only need be a valve at the hot end to regulate the flow so that the flow through the diaphragm orifice in either direction can be adjusted more to the left (venturi effect) or more to the right (back flow). - but I still think it is the standing waves set up due to this reverberation that accounts for the heat separation at the diaphragm opening more so, or rather than, the heat separation taking place due to the rapid spinning of the air in the vortex(s) in the hot tube. Of course, this is just another "guess". I'll probably have an entirely new theory by tomorrow, but I think it should be possible to discover something one way or the other through additional experimentation.

I'm splitting this off from the Stirling Turbine thread. I made a modification to the vortex tube and it is finally showing some action. I knew that the capillary tubing from the old air-conditioner that I was using for the "injector" or whatever it's called had a slightly smaller orifice than than recommended, by something like 1/2 mm. I thought if I added another, the two combined would be slightly over specs. (too much air input ?) but I figured that it was worth a try anyway: I looped another piece of capillary tubing around to the top and opposite side as shown, drilled the holes and soldered it into place. I plugged it into the compressor hose and tested it again. There didn't seem to be any change. Still just blowing luke warm air out both ends. I checked the measurements for the "Hot" tube length and carefully measured it out again and discovered that I had miscalculated slightly somehow. It was about 1 inch too long. I cut this off and tried again. Still nothing. I tried a few things. First I stuck some stainless steel wool into the end of the Hot tube again, as I had done before the modifications. This time the hot side started to feel nice and warm. The cold side felt cold, but not noticeably colder than the copper tubing normally feels, but the hot side most definitely began to warm up. I would guess it was just slightly above my own body temperature as it felt quite warm to the touch. Nothing dramatic but most definitely nice and warm. I should mention that I had not added a "stop cock" to the end of the Hot Tube side as I wanted to be able to experiment with it so I had nothing permanently affixed to the Hot end, so both ends of the Vortex Tube were open unless I was intentionally doing something to close them. So I stuffed some more of the stainless steel scrubbing pad in the tube. As I did so It got, perhaps just a little warmer up to a point but I could get no more out of it by adding more tan about 1/4 to 1/2 inch or so. Just enough to stop up the end. Then I tried various plugs to stop up the hot end with the steel wool inside. It seemed like this created some additional warmth and the cold side really started to feel cold. To see if the steel-wool was helping just because it was blocking the pipe like a rather porous "stop cock" I took it out and just plugged the end of the pipe with a Phillips screw-gun bit that fit snugly in the end of the pipe but which allowed some air to escape around it. This had about the same effect. But when I pushed the screw bit in tighter with my finger against the air pressure until the opening was almost completely closed there was a quite noticeable swing in temperature. The "hot" side got quite warm and the cold side got quite cold. Nothing that would fry an egg or cryogenically freeze anything yet but the thing was definitely showing signs of life. I could vary the temperatures by pushing the bit in tighter or looser. I took the bit out and was trying to see what kind of temperatures were coming out of the tubes without it by blowing the air on the back of my hand when I noticed something that seemed rather strange. I could not feel any air coming out the cold side. I put my finger over the hole and surprisingly, there was SUCTION ! My finger got sucked up tight against the hole like it was a vacuum. To test this more objectively I clamped the thing in a vice and tore a strip of paper out of a notebook and gradually brought the paper closer and closer to the tube. When close enough, within about two inches of the tube, the paper strip got sucked towards the tube and stuck to the end. There was most definitely a vacuum on the cold side of the tube, EVEN THOUGH I WAS BLOWING COMPRESSED AIR INTO THE TUBE AT 125 PSI !!! Becoming more and more amazed I noticed that the tube was STILL not making any noise. At least nothing in the audible range. It didn't sound any different than before the modifications, just a slight hiss of compressed air through the capillary tubes. In one You-Tube video I had seen a guy was apparently trying to take a temperature reading and his long thermometer probe got caught in the vortex and caused the thermometer to spin. I had tried doing the same before making the most recent modifications and got no effect. Now I tried it again using a round chain saw file that fit loosely in the tube. It started spinning !! There was definitely a vortex in there. I got carried away dropping various objects into the tube, or rather PUSHING them in against the air pressure. They did not spin until they got down to within about 2 inches of the diaphragm. The further in they went the faster they would spin reaching the greatest RPM when just about AT the air jets from the capillary tubes. At one point I wanted to see if the cold air side would get colder by wrapping some steel wool around the hot side to dissipate the heat. I did this at one point more or less absentmindedly WHILE I HAD A DRILL BIT SPINNING INSIDE THE VORTEX. As soon as I applied the steel wool to the tube, holding a steel wool pad around the tube with my hand, the RPM of the drill-bit inside the tube rose very sharply and dramatically. Apparently the vortex received quite a boost due to the more rapid dissipation of heat. Wow, this was getting to be fun. But the drill bit spun so incredibly fast inside the tube I was afraid it would fly out or do damage to the tube or the diaphragm, but I thought this would definitely be an area for some further experimentation down the road. Out of curiosity, to see what the effect on the temperatures would be while the Vortex Tube was doing "Work" spinning an object, I put the chainsaw file back into the tube and held the tube up on end so the weight of the file would hold it in the tube without me having to push it in with my finger while I checked the temperature of the tubes with the back of my other hand. This seemed almost as strange as anything. The temperature differential was now reversed ! The Hot Tube was now cold and the cold tube was Warm ! I took some of the aluminum fins off of the Air conditioners heat exchanger tubes and slipped them over the hot side of the vortex tube. I now found that with this additional heat dissipation, when I put the chain saw file back into the tube, it was possible to get it spinning even though barely inserted into the end of the tube if I had it balanced on end on the table. The tube was 8 inches long - so it seemed that the vortex had grown from about 2 inches from the diaphragm to the full length of the tube with the addition of the heat dissipating aluminum fins from the air conditioner. When I get to fooling around with this some more another day I think I will try making a stainless steel wool sleeve to go around the hot tube. I also noticed that during these experiments whenever the cold end of the vortex tube got cold the handle got cold also. The handle is soldered to the tube just for support. There is no air flow through this tube. It is only used to feed air to the capillary tubes, above that it is pinched off and soldered closed at the end but still attached to the cold tube for support. I think this handle is conducting a lot of heat to the cold end and perhaps the cold end could get much colder if it were removed. I will try both of these additional modifications next time. I might also mention that I made this small unit using the smallest possible tubing I could find (refrigeration capillary tubing) because I wanted to keep compressed air use to a minimum for all this testing. As a result, the compressor did not have to run continually or even very often to maintain a tank of compressed air. Still, the air volume or air flow was above what was specified. One was too little. Two capillary tubes was a little too much I think, but it was close enough to work to some degree. There were moments when the temperature of the cold end really seemed to drop down to what I would call "dangerously cold" temperature. Not really, but I would guess at least "ice cold". One other thing I tried. I cut a Styrofoam sleeve to put around the cold tube to see if insulating it would allow it to produce colder air. This did not seem to make any difference. Getting the cold tube down as cold as I could get it and then adding the insulation didn't seem to make a difference. There were some definite surprises in fooling with this thing. Phenomenon I had not seen mentioned previously. Most notably the vacuum at the cold end when the hot end was left open, the increase in the vortex size, velocity and strength with greater heat dissipation using aluminum fins or steel wool and the apparent temperature reversal when the vortex was doing "work" spinning an object. A very strange device gets even stranger. I'm having a little difficulty wrapping my brain around this things rather oddball behavior. Any ideas ? Strange to say, my acoustic theory seems to have fallen flat. At least this test model did not make hardly a sound. Not within any audible range of my hearing anyway. There was, most definitely a vortex after-all, and a surprisingly powerful one I thought for the size of the thing - able to spin rather heavy screwdrivers and what not that I was putting in there. Also the strength of the vortex, it seems, could be greatly increased by rapid heat dissipation so that it became stronger than what it was as just a "forced vortex" from the compressed air. I did not test this aspect of the thing very thoroughly as the objects were spinning incredibly fast without having them spin any faster. I would first like to make some sort of rod that can be controlled and prevented from lashing around inside the tube and doing damage to the diaphragm or something (like me) I was not very comfortable with the idea of drill bits and such spinning around at incredibly high RPM with nothing but some swirling air to hold them in place, especially when I had to hold them in the tube with my finger. It was real interesting but probably not real smart. I will make some videos of some of this strange phenomenon when I get the chance and the equipment to show temperature readings and such.

Well I went ahead and made another "Vortex Tube" from scratch being as careful as possible to stick with the specifications given. I used the smallest of the three configurations which involved using some tubing from a scrap air conditioner as it had the right size tubing. Here are some photos of the finished product: I hooked it up to the air line and cautiously started cranking up the pressure. There seemed to be a good steady flow of air. No leaks. I tried allowing some of the air to blow across my hand from a distance, But there seemed no difference in temperature. The air from either end seemed perfectly even. About the same as room temperature. I got the pressure all the way up to 125 PSI. As high as the compressor could go. I ended up actually putting the jets of air on my tongue to see if any difference in temperature at all could be detected. Not a thing. I did various experiments like using objects to block or partially block one end or the other. Insulating the pipes on one side or the other. I even put some stainless steel turnings in the end of the Hot Pipe as a "regenerator". This made no change. The tube made no particularly unusual sound. Just the sound of air flow. Reportedly these things create some sort of loud sound when working properly. I think this tends to rule out the idea that the vortex tube works by the air expansion alone. I think the air was certainly expanding through the tubes. One thing I thought I might have done "wrong" is when I drilled the hole for the air inlet I was a little afraid of getting too close to the "diaphragm" and may have drilled the hole a hair or two further away from the diaphragm than I might have done otherwise. So what difference would that make ? My thought is, If I did everything to exact specifications, as far as possible with materials at hand, I think I kept very very close to specifications, within 1/2 a mm or so, and it still isn't performing in the slightest little bit My best guess at this point is: There is some kind of necessity for some sound production. I'm thinking that the orifice between the Hot and Cold chambers or "diaphragm" with the hole in it with the jet of air swirling around it is what is supposed to generate sound. Kind of like blowing across the top of a pop bottle. If you have ever tried to do that it might be understood that this takes some finesse to get the air stream to cut across the bottle opening "just so" at just the right angle with the right pressure at just the right distance and so forth, It can be exceedingly difficult at times. It is easier to generate a tone with some bottles more than others, or, the effect may be something akin to rubbing a finger around the edge of a wine glass to cause it to sing. Or whistling. Some people just cant whistle for some reason. One of the names for this thing means "whistle" so perhaps that is accurate and perhaps the "diaphragm" is called a diaphragm as it is intended to be - like a loudspeaker, an actual sound producing, vibrating diaphragm and not just an orifice. If this is the case than quite possibly the reason for the failure is that the jet of air is just not hitting or not spinning around the diaphragm opening at the right angle or distance of something, so no sound is being produced. I imagine the diaphragm acting similar to a speaker in a thermalacoustic engine. One thing seems certain. There is some "trick" to this thing and it seems it is necessary to get it just right to get any effect at all. I was fairly certain when I decided to make a vortex tube that even if It was not perfect there would still be some detectable temperature difference. So far with these first two vortex tubes, I cannot detect any temperature difference whatsoever at all. Just regular plain old lukewarm - normal compressor air from either end. But so far neither one has produced any unusual sound either. Everyone who has ever had one of these things working has made mention of the loud sound produced. This seems a bit of additional confirmation that with no sound, there is no cooling effect, on the other hand, it doesn't seem there is much of any "vortex" being generated either. I'm thinking that this may require sound as well. A kind of acoustically driven vortex - if such a thing is possible.

Here is what looks to me like some additional confirmation of the acoustic theory: I reviewed the various information available again paying closer attention to size and proportions. An old graph gives a proportion of 1:32 Yes the newer working commercial model disassembled in one of the videos was measured to have an inside diameter of 10 millimeters and a length of only 80 millimeters. A ratio of 1:8 There is a common denominator here. These are octaves. Do Re Me Fa So La Te Do 1 2 3 4 5 6 7 8 8 16 32 etc. With this information I drew a graph with various possible waveforms thus: It can be seen how a full octave, that is, a 1:8 ratio between ID and length creates what might be called "Supernodes". That is, "standing waves" have nodal points but with a 1:8 ratio between inside diameter and length a resonant chamber is formed where all possible wavelength converge at the ends forming "supernodes". My theory at this point is that these "supernodes" create points where air molecules are forced to gather along the lines of the Chhaladni figures. One of these supernodes is located directly at the convergence point of the air inlet, the vortex "spinner" device which is supposed to create a vortex and the "diaphragm" that separates the Hot from the Cold chambers. By controlling the flow of compressed air with the valve/regulator at the end of the Hot tube the flow of compressed air can be, in a sense, "tuned" to the same frequency. That is as the molecules oscillate a corresponding volume of air is made to draw the accumulated molecules at the node through the hole in the diaphragm. Since the nodal accumulation, that is, since the wave form reverses continually, Once one accumulation of molecules passes through the diaphragm another node forms. I suspect that the speed of the air passing through the orifice in the diaphragm should be "tuned" so as to be proportionately the same as the volume of one unit of air per oscillation for maximum efficiency. By unit I mean the air volume contained within one segment of the pipe or resonant chamber. By segment I mean a length of pipe with a 1:1 ratio to the ID of the pipe as illustrated above. I may not be correct as to detail but I'm fairly certain that I'm on the right track. I will make some modifications to my model based on this acoustic theory and let you know what happens. BTW I measured the ID of my existing Hot Pipe and used this to mark off the length of the pipe using the ID of the pipe as a unit of measure. It turned out to have a length of about 11 and 1/4 "units". This is perhaps the worst possible ratio in terms of acoustics. Putting this into a graph similar to the one above, no wavelengths converged anywhere at all so that there was no possibility of any nodal points forming, except at the point that corresponded with the point where I was holding the tube and tapping it with a knife handle and it rang out, but very little. A few waves converged at that particular point when marked out graphically. I double checked this by marking the pipe according to the graph or measurements, that is, using the ID of the pipe as a unit of measure. Holding the pipe at that point it would make a ringing sound when struck. Otherwise it was a total dud. If I simply cut off the equivalent of about 3 and 1/4 units of measure off the pipe that would give it a 1:8 ratio.

After reviewing the available information about the Vortex Tube; sketches, diagrams etc. there is one theory (among many others) that the tube acts as an acoustic device. I also notice in some of the old sketches, such as on this page: http://www.visi.com/~darus/hilsch/ very precise dimensions are given and the length of the "Hot Pipe" in particular must be exactly 32 times the inside diameter. From my recollection of the news broadcast I saw years ago, it seemed that the guys being interviewed were just some plumbers working in their garage who had put some pieces of pipe together after cutting it to length with a hack saw of something and were just using the air hose to blow out the metal filings or something. They, along with the newscaster appeared genuinely perplexed by the mysterious phenomenon. The pipe appeared to be nothing special, just ordinary copper tubing put together in the usual way with a T shaped connection. If my recollection is correct, then these guys accidentally stumbled on some phenomenon by chance. They just happened to cut a length of pipe that turned out to be acoustically "Tuned" to the right pitch. If this is true, then possibly the action of the so-called "Vortex Tube" has little or nothing at all to do with any alleged "tornado" inside the tube making a reversal upon itself. At any rate, my modifications based on that theory led to complete failure. I picked up the length of my "Hot Pipe" and held it vertically between two fingers and taped on it with the handle of a jackknife as if it were a kind of wind chime. It was a dud. It apparently had no acoustic quality to it whatsoever. I tried again, holding the tube very gently between my fingers and tapping the tube with the knife handle while letting it slide down between my fingers slowly, like finding the right point on a guitar string by gently resting a finger on the middle of the string while plucking it to set up an acoustic standing wave. (The sound produced by this technique can be heard in the Led Zeppelin tune "Stairway to heaven". Sure enough, when I hit just the right point the tube rang out like a bell or a wind chime, but as soon as it slid down a bit further it turned back into a "Dud" and striking it with a knife handle just let out a dull thud. I've done a little guitar playing and I knew that if you find just the right point on the string and rest your finger on it gently it is possible to create a rather unique sounding resonance due to the standing wave formed. Note the proportional dimensions in this chart for the vortex tube: (lower right corner) It appears that the reason that the length of the "Hot Tube" must be in exact proportion to the inside diameter of the tube is that it is necessary in order to create a resonant cavity - like a musical instrument - drum, violin, guitar, bell, wind chime etc. In other words, the thing has to be precisely tuned. I'm thinking that the "Maxwell's Demon" effect of sorting molecules has nothing to do with any vortex, or at least not any vortex artificially created by some swirling device inside the tube, because, as far as I know or as far as I can recall, the guys in the garage on the newscast had not made nor had they inserted any such device at all. The phenomenon was a complete mystery, or so was the story. So my current idea or theory is that by creating a resonant chamber "Standing waves" are created inside the chamber which serve to "sort" the air molecules just like sand particles are sorted at the nodal points in a Chiladni figure when a violin string is drawn across a metal plate with sand scattered across it. Chladni Figure (Photo by Marek Chmielewski, http://www.mif.pg.gda.pl/index.php?node=stareinstrumenty&jezyk=en Gdansk University of Technology website) If this is all true then it should be possible, perhaps, at just the right pitch to easily sort hot and cold molecules with nothing more than a resonant chamber tuned to the right pitch, the rest of the elements going into the contraption being completely or almost completely redundant. The molecules thus sorted into "nodal points" in a resonant chamber could then perhaps be easily separated with little or nothing beyond a bit of compressed air. Perhaps nothing more than a simple throttling device, such as a washer with a hole in the middle. If there is a "node" formed through the center of the tube for example. Then one would only need to provide an escape route one way or the other for the sorted molecules to pass out of the tube in a more or less orderly way along with a bit of compressed air to send them on their way through the opening. It might also be noted that in my experiment as far as finding the right "nodal point" at which to hold my piece of pipe while tapping it with a knife handle, it may have been my imagination, I'm not quite sure, but it seemed that at the moment at which I found the right spot to hold the pipe between my fingers and the pipe began to ring out it suddenly and quite unexpectedly grew cold in my hand. As this was not at all expected I did not take any temperature readings or anything of that sort this would have to be verified but the sudden chilling of the pipe while it rang out seemed to me to be quite unmistakable, though, of course, this was my subjective impression and would have to be verified by further experiment. Theoretically though, if simply by hitting the right pitch or tone with the pipe at the right length the "hot" and "cold" air molecules could be effectively "sorted" into nodal points with the "Hot" molecules perhaps forming a node or LINE through the center of the tube, this would tend towards leaving the shell of the tube rather cold I should think. A different pitch or tone or length or diameter of pipe with a different Chiladni type formation might produce the opposite effect. P.S. Part of the reason I think this might be the case, i.e. the resonant theory rather than the vortex theory, is that in researching this I have found nothing to verify that any such vortex is actually formed. I would think that the formation of such a vortex would not require any particular length of tubing and I suppose, neither would it depend on an exact geometric relationship between length and diameter of tube. It would be a "forced vortex" created by the inrush of compressed air. Also, some of these models appear to have no real means of controlling such a vortex if it did exist, such as precisely crafted nozzles and so forth. Of course some DO HAVE, but other don't, and yet they still work without it so long as the dimensions are correct and in proper ratio even though using some crude valve from Home Depot as a control nozzle, which in my mind could not possibly effect a separation of different temperature molecules in the way described unless they had already been separated by some other means before reaching the end of the tube and the valve. As far as I know, no one has ever seen, analyzed, detected or otherwise provided any evidence that there is any kind of vortex at all involved. This seems to be nothing more than conjecture or theory, in spite of some elaborate drawings that have been presented to illustrate the theory, as far as I'm aware it remains a theory. On the other hand, there have been actual studies of the acoustics and it has been found that when certain sounds produced by the "vortex tube" are dampened or muffled or otherwise eliminated in some way the separating effect disappears, regardless or even in spite of any other conditions that might be involved. This information seems applicable: http://hyperphysics.phy-astr.gsu.edu/hbase/waves/opecol.html And this: http://hyperphysics.phy-astr.gsu.edu/hbase/waves/cavity.html#c1

Yes, that is Tesla describing his theory. But this is IMO at least, identical to saying; (if we applied it to the "drinking bird"): "by expending initially a certain amount of work to create a sink for the heat... to flow in" (He is only using water as a metaphore for heat i.e. If we first dunk the drinking birds head into the glass of water to create a heat sink for ambient heat to flow towards) "We would thus produce... a condition enabling us to get any amount of energy without further effort" (i.e. the bird will continue drinking so as to maintain the sink while also producing some energy). I realize Tesla was being, perhaps, a bit over-optimistic and envisioned something more than a toy bird generating a micro-amp but what he is suggesting IMO is no different in principle than the toy bird which does function as Tesla described. Once set in motion by getting its head wet and initiating a "heat sink" it keeps going on its own without any further effort on our part. Tesla was describing a heat engine and this bird is a heat engine that functions in the way he described, except perhaps in regard to the amount of useable energy produced. Could this principle be scaled up to produce some usable energy for practical purposes ? I'm not going to conclude its "impossible". At least not until somebody actually tries it. If the principle is sound, there are other more efficient ways of creating a "cold hole" than wetting 1/2 sqare inch or so of felt on a toy birds beak and much more efficient heat engines I should think.

Well, I couldn't resist. I had some extra time today so I tried my hand at knocking together a Vortex Tube. I didn't follow any specific directions. They seem so simple and I've seen so many examples online I thought I'd have no trouble making one. I even made some modifications I thought might make the thing work better at lower pressures (added an extra set of groves in a metal slug to generate the vortex). I hooked it up to the compressor and, forgot I only had it held together with duck tape for low pressure testing and the compressor was at 125 PSI or so and it blew all apart. I found the pieces and put it back together and started out at very low presure and gradually increased the pressure. Nothing much happened. The air came out both sides of the tube but otherwise there was no difference in temperature though the lower portion of the T that I was using for a handle did seem to get a little bit cold. Well, I did not follow any specific directions or make any accurate measurements as far as lengths of tubing and such, and it didn't work. I guess I should try making one to specifications to start out with. Apparently it does matter because I got no temperature difference whatsoever up to about 50 PSI when the thing came apart again. Disassembled: I might mention that as usual, after turning on the compressor the pipes leading from the compressor to the compressor tank got blistering hot.

Maybe, I'm not entirely sure. It seems like a gray area. Some things can look like, or in being described, sound like perpetual motion but aren't. The difference between one and the other can be rather subtle sometimes, especially if only going by a description. For example, If I say that I'm going to use a siphon to extract energy. I'm going to take the siphon and put it in some water and then put a turbine in the siphon tube and in this way get "free energy" indefinitely without having to do any additional work. Is that "perpetual motion" or isn't it ? Sounds like it and it could be, but maybe not. I didn't say that I was going to use the energy produced by the turbine to pump the water back to its source to start the process all over again making it a closed system. Also I didn't mention that by "some water" I meant a lake at a high elevation in an area of adequate rainfall to keep the lake filled. The difference is one is an open system the other isn't. I don't think Tesla was proposing a closed system. You can put Tesla's proposed engine in a sealed room and say "see, if you put it in a closed room it would be perpetual motion". But that is taking an open system and changing the conditions to make it a closed system and is not what Tesla proposed at all. But, I'm guessing you are right anyway. Probably couldn't work, but I still see it as a gray area. As far as I know, nobody has ever tried it, although in some respects I think the principle has already been demonstrated on a small scale, though even this is debatable I suppose. For example, there is no stable "heat sink" for the heat engine (in the following video) to run on. If this heat engine were to stop running for some reason the "Heat Sink" in the form of effective evaporative cooling would disappear. The cooling or "Heat Sink" is created "on the fly" through the engines own mechanical output. The engine uses its own power to maintain its own cooling system and so run on a combination of ambient heat and evaporative cooling but it is not "perpetual motion" because it is an open system. It is, in effect, a very small and inefficient ambient heat engine. Theoretically you could build a giant version of this thing and set it next to a lake and it would run and perhaps generate power "indefinitely". Looks like perpetual motion but isn't. But again, I'm afraid this is getting off topic here, even if it is "heat" related.

Here is a website about the Vortex Tube that includes a couple videos demonstrating a small commercial unit freezing water in a test tube and also recording the temperature differential produced. Also in the second video one is disassembled to show (close up and in detail), the inner workings. Vortex Tube Videos at http://www.machine-history.com/ One thought regarding the efficiency of the Vortex Tube. Some sites I have been reading suggest that the efficiency (For Refrigeration Purposes Alone) is Low compared to a conventional refrigerator. I am wondering though, how much of that "inefficiency" is due to the bulky compressors that would normally supply air to the unit. In a conventional compressor a tremendous amount of energy is wasted. In fact a typical shop compressor has cooling fins to help dissipate the "waste heat". Some say that ALL the energy used to compress the air by a conventional compressor is lost and that the only reason you can extract any energy from compressed air is due to the latent "internal energy" not due to any energy added by the compressor. This is all lost as "waste heat". I think if there were a "compressor" that ran on heat so that all of this "waste heat" could be utilized the overall efficiency of this, or any air-cycle type heat exchange system utilizing compressed air as a refrigerant would be greatly increased.

As far as the heat engine is concerned, I could really care less about entropy & the second law. I just want to know if there is any chance in Hades of the thing actually working. If the second law doesn't apply because it is not a closed system then I can stop worrying about finding loopholes in the second law.

But how can you really gauge complexity / order ? I used to have this problem with my X-Girlfriend. I had some manuscripts I'd be working on and would have the chapters all organized so I could look everything over at a glance - spread out on a long table. Very complicated but well organized, slips of paper inserted between pages with notes, cross references, footnotes etc. Whenever I went out though my girlfriend, in the process of straightening up the house would get things neat and organized by picking up my mess on the table and putting it all into a box in the back of the closet.