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Tom Booth

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  1. No, it doesn't make sense. The process, if it can or could work at all, would have to be given an initial boost, like most anything. A regular Stirling engine for example has to be given a push to get it started. Your car needs a starter motor etc. This thing would also have a bit of difficulty getting started I think. At least some external source of compressed air to get it charged up and get air flowing through it. This "charging" would have to continue for some time until the turbine started putting out some cold air to establish a temperature differential in the displacer chamber. Once the turbine starts, it would need to be put under a load. The energy drain should, theoretically, make the air coming from the turbine extra cold. Once the turbine starts generating some cold and electricity then the electric power output from the turbine can start delivering the current to the solenoids and the controller motor to actuate the displacer movement. So now everything has come full circle and you should be able to remove the external source of compressed air. I've been working on that animation today and finally got something done with it. It doesn't show every detail. Like I didn't bother showing the cold air exhaust or the turbine turning - but there is not much action to see there anyway. I made some captions, but they probably go by too fast for anybody to read. I also don't show the full cycling... mostly just the air being driven down to cause the air to contract the cooling coils is sort of missing - the displacer just kind of snaps back - but I think it is pretty good to illustrate what is supposed to happen. http://prc_projects.tripod.com/stirling_air_turbine_anim.html This shows the engine running after it has been started. Admittedly, it might take some doing to get it going, but once the full cycle has been initiated, it looks to me like it might just continue on its own - as long as the load is maintained on the turbine, i.e. IT HAS TO DO WORK TO OPERATE. The turbine doing work is where you get that little bit of extra cold to compensate for any inadvertent heat infiltration. Originally this thing had about a 15 foot diameter parabolic solar dish focusing heat on it... Originally I was just trying to use the Air Cycle to keep the Stirling Engine from overheating... But once I came up with this configuration it seemed like adding any additional heat would be TOO MUCH HEAT. It seemed to be running fine without the direct solar input. It seemed to be getting enough indirect solar heat right from the air... Of course, a little extra solar heat on a cold day probably wouldn't hurt. Here it is again: Stirling Turbine Animation
  2. Thanks for the tips. I'll see if I can wrap my brain around this and figure something out. Merged post follows: Consecutive posts merged Hi, There is a diagram I posted earlier: http://prc_projects.tripod.com/stirling_air_turbine_2.html There are a few details missing. For example: the displacer (What I've labeled "inturbulator") would probably also need to be a "regenerator". That is, it would be comprised of a top and bottom plate with slots or fins to help swirl the air as it passes through the thing with some stainless steel-wool or mesh sandwiched in between. The regenerator is a common component in many Stirling Engine displacers, but I've heard from some Stirling Engine model builders that they found that their engines run just as well or even better without it. For this engine though, after trying to visualize the heat flow in this thing, I think the displacer would need to have some regenerative capacity. Here is a You Tube video animation illustrating how the displacer's movement creates alternating pressure and vacuum to drive the piston in a conventional "Gamma" type Stirling Engine (without a regenerator), which is the same basic design I've used except that I'm using check valves so that the expanding gas escapes rather than pushing a piston and the vacuum draws in fresh air through a second check valve rather than sucking a piston back in: http://www.youtube.com/watch?v=CDntL4GZh0E I've been trying to find the time to make this simple diagram into a gif animation showing air and heat flows, pressure changes etc. but I still haven't had the time. I'd have to draw the images by hand frame by frame. For now, I can say that the air goes in the intake and pretty much keeps going the same way (flowing through the tubes) until it exits through the exhaust. I've tried to illustrate heat changes in the gas with color (red=hot, orange=warm, blue=cold). I have also neglected to show insulation. There would need to be a lot of it. Basically you can assume that anywhere the gas traveling through the system where the pipes or other things the gas is passing through are not intentionally exposed to ambient air for heat exchange would need to be well insulated. I can add some arrows and insulation to the diagram.... Maybe it won't be too difficult to make this animated, as there are not too many moving parts. Merged post follows: Consecutive posts merged I think that if this were true, a Stirling Engine wouldn't work either, the theory and operation of which is based in part on the principle that it takes less energy to move the displacer than what can be recovered from the force of the resulting expanding and contracting volume of air. I don't see how converting the expansion and contracting force into a linear flow making it possible to use a more efficient turbine instead of a piston would alter that equation. In a conventional Stirling Engine, ultimately everything (all the moving parts of the engine) is driven by the temperature differential. The temperature differential can be above or below ambient. If above ambient, then ambient is used as the heat sink and heat has to be added. If below ambient then ambient is used as a heat source so heat has to be subtracted. The problem is how to subtract enough heat from the system to maintain the cold side of your temperature differential. This thing is basically a long condenser coil throwing off heat. By keeping the turbine insulated, more heat is extracted to do work rather than added in the expansion phase. Theoretically, an enormous amount of heat/energy is being extracted from the air creating a huge temperature differential. The displacer is relatively light weight and encounters very little resistance as it does not expend much energy in moving the air. It is not directly expanding or compressing the air, the air just goes right around it or through it. The turbine should be able to extract more energy than would be needed to move the displacer, just as the piston in a conventional Stirling Engine can extract more energy than needed to move the displacer.
  3. I think we've covered that. As far as I can see, any heat transfer that is going on is always from warmer to colder. But just for clarification, the "compressor" isn't really a compressor exactly, and it isn't doing any work on the gas directly. By utilizing the temperature differential, the gas is being made to do work against itself. By being heated inside a closed chamber the gas expands and escapes through a check valve - something like steam escaping from a pressure cooker. Then, (continuing with the pressure cooker metaphor), the gas in the "pressure cooker" is then cooled, creating a partial vacuum inside the "pressure cooker" that draws more fresh air in. This fresh air is then heated and made to expand and escape... etc. etc. The check valves keep the air that has already escaped from being drawn back in when the "pressure cooker" cools. There is no "work" as such, being done by the "compressor". The "compressor" is just a closed chamber like an empty pressure cooker with some check valves added on to it. It functions LIKE a pump or a compressor but it doesn't actually do any "work", any more than a pressure cooker does "work". What is doing the work to expand the air and keep it moving is HEAT. Ultimately the "ambient" heat of the air itself which has been concentrated in one area by the air cycle "heat exchanger" into which the "pressure cooker" is "pumping" the air. Let me try to continue with the pressure cooker idea so as to hopefully make this clear. The "displacer chamber" is just that. a CHAMBER. Lets call it a pressure cooker just for illustrative purposes. There is a volume of air inside the "pressure cooker". If we heat up the pressure cooker, the air inside will try to expand creating "pressure" if it has nowhere to go. We give it a place to go by drilling a hole in the side of the pressure cooker and installing a check valve so that the air can escape but not get back in. After heating the pressure cooker and allowing the gas to escape, we now plunge the pressure cooker into some ice water. The air inside cools rapidly and contracts creating a vacuum inside the pressure cooker. To utilize that vacuum we drill another hole and install another check valve that allows the air in but won't let it back out - So the pressure cooker sucks in some fresh air. Now we heat it up again - again the air escapes through the first check valve. Then cool it down - more fresh air being drawn in through the second check valve. In other words, the "pressure cooker" doesn't do any "work". The temperature differential is doing the work of pumping the air through the pressure cooker. There really is no compressor, but the "pressure cooker" for all practical purposes is functioning as an air pump or compressor without doing any work. The temperature differential is doing the work. Thanks, I'll check those out. I'm pretty sure I could figure out the math if I just knew what variables to insert into the equations. The main question is, to begin with, can a "pressure cooker" work as a "compressor" or air pump as I've just tried to describe ? If it can, how many CFM at what initial temperature differential ? I'm imagining that if the outlet to this "pressure cooker" were connected to a tank rather than the open air it would be able to build up pressure in the tank which would be limited to some point below the pressure that could be developed within the pressure cooker itself if it had no outlet. We start out with the "pressure cooker" full of air at ambient temperature and normal atmospheric pressure. We alternately heat and cool it (or just the air inside it) with the temperature differential provided by the air cycle heat exchanger system. The air being "pumped" by the "pressure cooker" is being used to provide the air flow for the air cycle heat exchanger which is in turn providing the temperature differential needed for the operation of the "pressure cooker". There are a few additional tricks being played on the air along the way to increase the temperature differential. The air being "pumped" out of the "pressure cooker" is being redirected back through some tubes inside the "pressure cooker" so that the heat is recirculated and concentrated inside the "pressure cooker" then when it leaves the coils inside the "pressure cooker" it is cooled by sending it through another set of coils which are exposed to ambient air temperature. This second set of coils is used to drive of any excess heat and get the temperature of the air back down to ambient. It is then, possibly, cooled some more in another set of coils utilizing the cold exhaust from the turbine, bringing the air temperature down below ambient while it is still somewhat compressed. Finally it is released into a well insulated turbine where it expands and does some work turning the turbine against some load on the turbine, upon which its temperature drops precipitously well below ambient temperatures. As the cold gas leaves the turbine it is directed back to the "pressure cooker" to be utilized for cooling the pressure cooker to draw in a new supply of air. The only thing I've left out here, in this "pressure cooker" explanation is how do you apply the heating and cooling to the "pressure cooker". Well, you don't actually heat and then cool the "pressure cooker" at different times. You heat and cool it simultaneously. Heat the top and cool the bottom. Here is where the "displacer" comes in. All the displacer does is move up and down inside the "pressure cooker" displacing the air. As the displacer moves up, the air is displaced and moves down against the cold side of the "pressure cooker" causing the air to contract and creating a vacuum inside the "pressure cooker" that sucks air in through one of the check valves. Then when the displacer moves down it displaces the cold air forcing it up against the hot top of the "pressure cooker" where it expands and escapes out the other check valve. The resulting flow of pressurized air out of the "pressure cooker" is sent through your air-cycle heat exchanger. The only power input needed for this entire system (other than the heat in ambient air) is whatever energy it takes to move the displacer up and down inside the "pressure cooker".) The "pressure cooker" acts as a compressor for your air-cycle heat exchanger.
  4. Yes, I kind of figured there might be something in the math that would thwart all this. I did finally find a paper online that appears to contain some equations that might be applicable: Experimental and Computational Studies on Cryogenic Turboexpander This is a PDF Document (3.37 Megabytes): http://ethesis.nitrkl.ac.in/7/1/sghosh-sarangi.pdf I have found this to be essentially true: clip---------------- "The expansion turbine constitutes the most critical component of a large number of cryogenic process plants – air separation units, helium and hydrogen liquefiers, and low temperature refrigerators... "A basic component which is essential for these processes is the turboexpander. "The theory of small turboexpanders and their design method are not fully standardized. Although several companies around the world manufacture and sell turboexpanders, the technology is not available in open literature... "...this technology has largely remained proprietary in nature and is not available in open literature. "Small turboexpanders have found extensive application particularly in cryogenic refrigeration and liquefaction systems, small liquid oxygen and nitrogen generators, helium liquefiers and emergency power packs. While the basic technological principles are well established, finer aspects of technology still remain proprietary information in the hands of a handful of international companies. --------------------- The majority of the information I've gleaned about the various uses of these turbines has come from the trade literature. However, any grease monkey with his hat on backward can tell you that an air tool produces both power output and extremely cold air. Years ago, when I first started working in an engine repair shop, the first thing I was instructed on was to watch out for certain air tools and to keep my hands away from the air discharge port as a former employee had gotten his fingers frozen to one of the tools. I did some of my own experiments with these common tools. While under a load, they emit extremely cold air, but not otherwise, only when being used to do work. I've seen pictures of these turbo-expanders disassembled in some of the trade literature. They don't look like anything special, just regular turbines. It seems to me that any turbine would produce this effect to one degree of another, and could be used to produce both a power output and cold air, without diminishing the power output. The cold air is a bonus. If this Stirling Turbine runs at all, it would have to have some kind of power output at the turbine. It would also have to have some cold air output as a consequence. The driving mechanism for the compressor in this engine is a Stirling Engine type displacer which has virtually no friction. The displacer is virtually suspended in mid air by electromagnets (solenoids) which control its movement. I don't know if you have ever made an electromagnet, but I used to play around with them as a kid - powering them with a small flashlight battery, and as I recall, one flashlight battery would power an electromagnet for hours of fun lifting heavy metal objects. Other than the heat in the ambient air. The only power consuming element in this engine is the two electromagnets (solenoids) controlling the movement of a very light weight displacer with almost no friction involved in its movement - that could conceivably run for hours on a flashlight battery. If this does function as an air compressor, as it seems it would, given a temperature differential, it looks like it's all down hill from there. The only other loss would be the friction of the turbine bearings and air to air friction or air producing friction against the pipe walls etc. But in this configuration, even much of this heat/friction is put to good use. My main concern is that this Stirling type compressor operating on a temperature differential simply will not work for some unknown reason, though I can't see any immediate reason why it shouldn't work. The same basic displacer set up works to power a piston in a heat engine, why not a turbine ? The only difference, as far as I can see with that is that the check valves are converting the reciprocating expansion and contraction of the air in the displacer chamber into a linear flow so as to power a turbine instead of a piston. The power output should be comparable to that of a regular Stirling Engine. If what it comes down to is the math, I'm afraid that for me at the moment, it would be easier to just go ahead and build a small model engine and see if it works. That seems a lot less complicated and should be relatively easy to do. If the concept works at all, it should work on any scale... Then I can post the video on You Tube.
  5. That's good. I wouldn't be opposed to moving the discussion to a new thread though, it is somewhat off the topic of the Kender thing, and... well, if it does turn out to be bogus,... I'm not sure how much I'd want to be associated with it. (and maybe vice versa) I can think of a few reasons why it might have less chance of working than my own hair brained idea. Like using a regular energy consuming electrically driven compressor, I'm not sure I understand the rationale behind using helium, I have no real idea what mechanism they intend to use to extract any energy (I'm assuming the turbine, but they show no load connected to it)... It seems the energy input might be more restricted by using a closed system. I would think that the "solar" panel, on a calm windless day would develop a halo of cold around it... All I can think is that if it did work, the extreme cold that the helium could theoretically reach might create a wide enough temperature differential to compensate for all that somehow... I can't really figure any way around that one at the moment. All I could figure is, no insulation is 100% perfect and you would still have some loses and the room would still lose or gain some heat energy to the walls, floor etc. by conduction, and the thing would quit running eventually - or keep running. There are some people though who say perpetual motion is the rule rather than the exception. clip-------------- "Notes on the properties of matter and heat "We hear much of the impossibility of perpetual motion. As a matter of fact, perpetual motion is the rule of nature. It is impossible only in the limited sense that a body cannot overcome resisting forces, thus doing work, without being supplied with energy from some external source, or in other words having its motion replenished at the expense of other moving bodies. " http://www.archive.org/stream/notesonpropertie00lewirich/notesonpropertie00lewirich_djvu.txt ------------------ But this is a rather compelling argument against this thing working I think. Hmmm... Well, if this thing (The Stirling Turbine) is sending energy to the electric grid, there is also some energy being transfered to outer space. Street lights, infrared radiation of various sorts. The only problem ? What about the negative entropy thing ? And you have pretty much proven that if it worked, it WOULD be (virtually at least) perpetual motion... But if making a gas do work against a turbine as it expands reduces its temperature, more than it would be reduced by expansion alone, where is the extra "heat" going if it is not being converted into the kinetic energy of the turbine, and if the heat is not being converted into kinetic energy, why bother with making it do work against a turbine ? As I understand it, (or not) The gas has quite a reserve of internal "heat" energy, and by allowing it to expand into an environment where there is no external heat available, it will draw on its own reserve of internal heat/energy. Initially, if the gas were allowed to expand through an insulated turbine it would draw heat from the turbine to do the expanding - until the turbine itself grew cold. When the turbine is as cold or colder than the gas then the entropy thing would seem to allow that heat/energy could be transfered from the gas to the turbine as it is doing work against it - causing the temperature of the gas to drop as a result of this internal energy being transfered to the turbine to do work. As the temperature of the gas and the turbine are the same the gas has to eventually draw on some of its own internal kinetic heat/energy to do the work. In other words, the pre-cooled compressed gas shooting out of the nozzle under pressure wants to expand - like a spring being released, but it needs energy to do so. But since it is expanding into an environment that is already cold, it has to draw on its own internal heat/energy. I hope you will forgive my blurring of the gas molecules kinetic and heat energies, but from how the theory of how the turbo-expander works, the "heat" of a gas IS the kinetic energy of the gas. If I'm wrong, then my sources are wrong, though I've read this explanation and watched explanatory videos about it and they all say the same thing. i.e.: By keeping the turbine insulated, this forces the gas to draw on its own internal kinetic/heat energy to do the work against the load on the turbine. So, you are right, in a way. The heat energy in the gas is actually the kinetic energy of the gas molecules, so the insulated turbine isn't exactly "converting"thermal energy into kinetic energy, it is just causing the gas to give up more of its kinetic energy than it would otherwise use for relatively uninhibited expansion. But again, that's just semantics. The expanding gas, upon giving up its reserve of kinetic energy to do extra work against the load on the turbine gets extra cold. More so than from expansion alone. But we need some way of putting this in simple terms so I still think it can legitimately be stated that in effect the turbine coverts its heat energy into kinetic energy resulting in a drop in temperature. Without the turbine, the gas will still get cold when it expands, but not cold enough for some of these extremely low temperature processes. That is the explanation I've read as far as what is going on anyway. If it is wrong, then my references are wrong. But I don't think it is wrong or the expansion turbines would not be in use for this purpose. Now of course they are used in other applications - like energy reclamation where they are not insulated and the extra cooling isn't needed, but I'm talking specifically about things like the liquefaction of gases, cryogenics and other very cold temperature processes where the turbine is kept insulated to force the gas to give up its own internal energy (heat) to do work so as to reach the colder temperatures.
  6. LOL... You don't think I'm a Kender employee do you ? I first found out about this Kender engine here. It sounded rather similar to my engine, which is why I posted in this thread, but perhaps that was a bad idea.
  7. This is true, and makes perfect sense if you are talking about a closed system where there is no input of energy. Say for example that the thing is running in a sealed up room. Once it has extracted as much of the heat in the air in the room as it can, the room will be at least as cold or colder than the machine itself. There isn't anything external to the system to warm up the room so as to continue providing heat to run the engine. I think it is a different story though, if your source of hot air is the open atmosphere, the heat of which is continually being renewed by the input of solar energy. I've had a hard time finding any mathematical formulas that might apply to this, as it seems all the formulas assume a closed system. Maybe if the sun and the earths atmosphere are considered part of "the system" this might work out mathematically. Somehow this dippy bird contraption manages to sidestep the scenario you portrayed above. It also draws in heat at its base and outputs cold at the head and kinetic energy, yet, starting out, the bird is at ambient temperature and so is the water. But it wont start dipping on its own. Some outside force has to get it started. Somebody has to dunk its head in the water to get it going, but once initiated, it manages to throw off the excess heat fast enough so that its temperature never quite equalizes... and so it keeps going. Same idea with this "Stirling Turbine". Of course, It is not "perpetual motion". Even if the parts never wore out it would still come to a stop eventually - when the sun finally burns out or something. The reason the warm air doesn't eventually warm up the dippy bird is that due to its mechanical action, it is always throwing off the excess heat by absorbing more water to evaporate. Theoretically, this engine would also throw off the excess heat. Not through evaporation, but by pre-cooling the compressed air being delivered to the turbine using more or less conventional refrigeration methods and then forcing the air to give up some ADDITIONAL heat by making it do work at the turbine - in effect - dumping the excess heat by converting it into the electromechanical energy leaving the system. I'm wondering though... In the closed room scinario... What would happen if you used the output energy from the Stirling Turbine to run an electric heater inside the same room ? I suppose there would still be some loss somewhere due to sound waves or vibration and such leaving the room. I don't know, the whole thing is probably impossible due to one thing or another. On the other hand, supposedly Einstein couldn't figure out how that little dippy bird thing worked. I think it basically works, overcoming what you stated above, by throwing off as much or more heat through evaporative cooling than what it absorbs... and by ultimately converting a portion of that heat into kinetic energy, managing to keep one step ahead of the heat by using the kinetic energy derived from the heat to keep renewing its cooling mechanism - like a donkey chasing a carrot - the heat can never catch up and in the process, useful work can be extracted. The turbo-expander can simultaneously cool the air in two ways, the air cools as it expands naturally, but cools a little extra due to being made to do work. It is that little extra - ultimately exiting the system as electricity that keeps the system one step ahead of the heat. Without that electromechanical load on the turbine, providing that extra degree of cooling, what you said above would certainly be true.
  8. I am wanting ? No I'm not. From what colder object to what warmer object ? Could you please be more specific. Maybe I'm missing something, I don't know, but you are making an assertion or generalization without applying it to anything specific. If you don't understand what is supposed to be going on at any point in this system, how can you make such a generalization ? Where is heat supposedly being transfered from a colder to a warmer object at any point in this system without expending energy ?
  9. How, or in what way, or at what point do you see entropy decreasing in this system ?
  10. LOL... OK, if you don't understand it, how do you know it won't work ? It uses the same principle as the dippy bird but on a larger scale. BTW... The dippy bird, as you say, runs on evaporative cooling yes ? Where does the energy come from to do the evaporating then ? This is a change of state, and to evaporate, the water has to absorb heat/energy. Where does that heat/energy come from if not from the air ? So you have two processes going on, both of which utilize the ambient heat in the air. A heat engine and evaporative cooling. The evaporation causes the birds head to loose heat because the water requires energy to evaporate and absorbs that heat/energy from the air, which provides the temperature differential for the heat engine to convert the temperature differential into a pressure differential which then allows the pressure differential to be converted into kinetic energy. The same process is going on in this engine except that it is using the turbo-expander to extract the heat instead of evaporative cooling. It is the same principle. So why doesn't the dippy bird work ? If there is some flaw in the principle that makes it "impossible" then the dippy bird shouldn't work either.
  11. What motor ? There is no motor in my engine. By "in this case" I was referring to my Stirling Turbine in case that wasn't clear. It has no motor to turn the compressor. The "compressor" pumps air by means of a temperature differential. Have you by any chance taken a look at the sketch I posted of this thing ? So, I guess what you are saying is that in a conventional... whatever we are talking about... the motor turns the compressor which supplies the compressed air to the turbine, so without the motor turning the compressor, the compressor won't compress and the turbine wont turn and so there will be no temperature differential.... Granted, I think I follow all that and it is quite obviously true, but not for the engine, or whatever you want to call it - Stirlingish Turbine thing that I'm proposing. The compressor in this case compresses the air by using the temperature differential. There is no motor. There is a metal box or can that is made hot on one side and cold on the other and the air inside is shunted back and forth. As the air hits the hot end of the box it expands and some of it escapes through a port with a check valve then when whatever air is left in the box is shunted back to the cold side the remaining air contracts and the resulting vacuum produced inside the box draws fresh air in through another check valve. This fresh air is then shunted back to the hot side where it again is heated and made to expand and escape through the check valve. This continues on and on back and forth expanding and contracting, drawing in fresh air, heating it up so it expands under pressure and escapes into a coil. There is no motor. If the air is being compressed, the turbine doesn't care what is doing the compressing. A motor driving a compressor or a Stirling type displacer chamber with check valves. It is the same compressed air either way. If the displacer moving back and forth and using very little energy just to move the air from one end of the box to the other - and in the process using an existing temperature differential to expand and contract air to push and pull a piston that turns a crankshaft and does work, deriving more energy to do work from the expanding and contracting air than what it takes, with the help of the temperature differential to expand and contract the air - then the same displacer, moving air back and forth and using very little energy should also, by converting the expanding and contracting air into a steady flow of air with check valves - delivering a steady stream of compressed air to the turbine, should be able to get more power from the turbine than what it takes to move the displacer, which only shunts a volume of air from one end of a box to the other, taking advantage of the temperature differential to expand and contract the air and converting this alternating expansion and contraction into a steady flow of air to the turbine... With a few other thermal operations performed on the compressed gas along the way... Have you looked at either of these drawings I posted previously ? http://prc_projects.tripod.com/stirling_air_turbine.html http://prc_projects.tripod.com/stirling_air_turbine_2.html
  12. And a fire will go out in an air tight box and a car will quit running in an air tight box and living things will suffocate in an air tight box So what ? We aren't talking about perpetual motion here. Right. "recuperates" some energy. Right, "cool enough". I don't understand what you are trying to say here. What's your point ? I think what you are talking about here is liquefaction of gasses. The application there is to liquefy the gas, not produce power. In my engine the gas is ALL allowed to expand. Right. Same thing here. The air is compressed and the heat transfered to the hot end of the displacer chamber. Then the air is allowed to expand and heat is transfered to the gas from the other cold end of the displacer chamber. Right. OK True, but not as much of a temperature differential as with the turbine. In this case, the energy being used by the compressor to compress the gas is coming from the temperature differential that results from the compression of the gas and expansion of the gas through a turbine. This compressor runs on a temperature differential. Ultimately, the ENERGY to run it is coming from the heat derived from the same gas that it is compressing, which heat is coming from the ambient air, just amplified by compression. The turbine is also running on whatever heat energy is left in the air molecules as they expand. Ultimately this energy to run the turbine is also coming from the ambient air. First the compressor uses some of the heat in the air, then the turbine uses more. What you have left is cold air at the turbine which gives you your heat sink and temperature differential to run the compressor. Without the turbine extracting some extra heat and converting it into another form of energy, there would not be enough temperature differential as the total energy of the system would remain the same. By exporting some of the heat energy as electricity it should be possible to maintain the temperature differential. Just expansion and contraction of the air by itself would not maintain a temperature differential for very long. That would be like the dippy bird in a box. No energy would be leaving the system. But this thing is not a perpetual motion machine and it is not in a box. It is drawing in and expelling air all the time. So what if it wouldn't run if enclosed in a box. It isn't supposed to run enclosed in a box, it is supposed to run in the open air. It has an energy source, the solar heat energy trapped in the air. Of course it wouldn't run if it didn't have a hot air supply. Relatively speaking, ambient air at whatever temperature is "Hot" compared with the bitter cold produced by the air-cycle system. This combination of an efficient heat driven air compressor and air-cycle system is where you get your temperature differential. Everything is running on heat. The turbine is extracting some of that heat and exporting it as electricity leaving "cold" for your temperature differential to run the compressor to convert the temperature differential into a pressure differential to run your turbine to produce a temperature differential to run your compressor. As far as the internal workings of this thing are concerned, the electricity being generated by the turbine is a "waste product" or excess heat that needs to be gotten rid of in order to maintain the temperature differential. The bird works on the same principle: "The drinking bird is a heat engine that exploits a temperature differential to convert heat energy to a pressure differential within the device, and perform mechanical work." http://en.wikipedia.org/wiki/Drinking_bird "The drinking bird is a heat engine, using temperature differential to convert heat energy to a pressure differential with the bird. Heat engines operate through a thermodynamic cycle. It is not a perpetual motion device." http://www.helium.com/items/1651468-how-a-drinking-bird-works Who cares if it won't work in an air tight box so long as it works ?
  13. That is merely semantics IMO. Yes, you can say that these "run on" a temperature differential, but I don't believe that that is entirely accurate in terms of where is the energy coming from ?. You could say that a gasoline engine runs on a "pressure differential". But what, ultimately is the cause or source of the energy ? --------------------- "The dipping bird obtains its energy from ambient heat..." http://www.vectorsite.net/tpecp_10.html "...where does the bird get its energy? As you may have guessed, it gets it from the surrounding air..." http://morningcoffeephysics.wordpress.com/2008/11/09/physics-explained-through-a-drinking-dippy-bird/ ---------------------- I'm pretty sure it doesn't. The turbine - driven by the expanding gas transfers that energy to the compressor through a shaft helping to take some of the load off the compressor. True, and that depends on the application. i.e. what type of gas is being liquefied. Some gases are easier to liquefy than others, i.e they liquefy at higher temperatures. With gasses that are harder to liquefy, a turbo-expander is used to make the gas do additional work thus drawing away more energy and making the gas that much colder as it will not liquefy due to mere expansion alone. If such gases would liquefy just do to the expansion, what is the point of adding the turbine ? The turbine is used to make the gas do additional work so as to draw off additional energy and thus obtain the colder temperatures needed to cause the gas to liquefy as some gases will not liquefy from the cold produced from mere expansion alone. If the turbine wasn't taking energy out of the gas to make it extra cold what would be the point - if it got just as cold anyway from expansion alone ? Turbo-expanders are used where extremely cold temperatures are needed - like in cryogenics as the usual refrigeration methods using expansion and/or "evaporation" alone can not do the job. In such cases a turbine is added to make the gas do extra work - removing energy - making the gas get that much colder. That lost energy is transfered to the turbine which can either be coupled to a redundant load or it can be used for energy recovery i.e. coupled to the compressor. The load on the turbine is often external to the system. In an air cycle system, generally, the turbine is coupled to a generator (i.e. a turbo-generator) and the electricity produced is used to power something, often just a redundant load, anything - just to draw off the excess energy - or it may just be coupled directly to a fan of something where the fan uses up the excess energy by transferring that energy to the air. None of this has anything whatsoever to do with the temperature differential "maintaining a load on the turbine". The temperature differential has nothing to do with "maintaining the load on the turbine". It is just the opposite of that. The load on the turbine is what helps maintain the temperature differential by drawing off excess heat/energy in order to provide the additional cold to maintain the heat sink. Normal cooling from expansion alone wouldn't maintain any temperature differential for long - as the total energy level in the system would remain the same and would eventually equalize - but with the turbo-generator the heat/energy is being transfered out of the system as electricity. With the heat being taken out, cold is left behind maintaining the temperature differential between ambient (hot) and the resulting cold due to extracting heat/energy at the turbine and converting it into electricity. Ultimately your load on the turbo-expander-generator is maintaining your temperature differential, the temperature differential doesn't "maintain the load", it indirectly supplies power to the load. The temperature differential is used to compress gas, the compressed gas is used to drive the turbine, the turbine drives the generator the generator delivers electricity to the remote load somewhere. As the compressed gas drives the turbine the gas gets cold as the energy from the gas is being converted into electricity. This cold is a kind of by-product of generating electricity with a turbo-expander powered generator. This cold is then available to supply the necessary heat sink to run the compressor utilizing the temperature differential between the cold air produced by the turbine and the warm ambient air of the environment (which has been made hotter than ambient temperature by compressing it through some narrow tubing).
  14. Sort of. Except in this design, the displacer unit (which is the heart of a heat engine) also doubles as the compressor for the heat pump. Probably 95% of the mechanical inertia, drag and friction of the heat engine has been eliminated and 100% of the power drain from the heat pump's compressor has been eliminated by combining the two functions into one efficient unit. True, but you are here describing a conventional refrigeration system not an Air-Cycle System where additional heat is extracted from the expanding air by making it do work against a turbine. You seem to be under the misconception that the turbine is being powered by a motor or something and that it is pulling or drawing out the gas, causing a partial vacuum and a lowering of the temperature of the gas, and at the same time you are under the misconception that I am under the misconception that the expanding gas is actually driving or pushing the turbine when it isn't. I think I can assure you that I am not the one under a misconception. If you read the literature and look at the illustrations regarding the use of expansion turbines or turbo expanders for cooling (refrigeration/air-conditioning,freezing), power recovery, liquefaction of gases etc. It is very clear that the expanding gas is driving the turbine and that power is being extracted from the gas by the turbine and that as a result of this energy expenditure of the gas working against the turbine the gas gets cold. True. And the energy to do that work of expanding has to come from somewhere. If, due to being insulated in some way, there is no external source of heat the air molecules have to draw upon their own internal energy (Joule-Thomson-Effect) to do the expanding, as a result of this energy expenditure, the gas gets cold. But if the gas is made to do additional work as it expands (such as turning a turbine), and there is still no external source of heat, it will get even colder than it would from expansion alone. I don't think there is any violation of the laws of thermodynamics. The displacer is not "creating" heat. Just moving it to where it can do some useful work. Further, the turbine is converting some of the heat energy into mechanical/electrical energy. That portion of the heat - leaving the system as electricity creates an imbalance or a flow of energy out of the system - a kind of heat sink as far as a gas is concerned, but that heat energy leaving the system has not been "destroyed". It will re-emerge as the electrical energy is expended at some remote location, such as to light a light bulb or heat up a heating element somewhere. Eventually that heat energy leaving the system will make a complete circuit and be drawn back in. In other words, as long as there is a load on the turbine, you can maintain a temperature differential and it does not violate anything. If you removed the load, then the system could not continue to operate. . Not really. With the evaporation energy is being taken away. The bird does not run on the energy being taken away at its beak, it runs on the ambient heat energy warming its bottom. True. The evaporative cooling on the beak drawing off heat/energy is the equivalent of the load on the turbine drawing off heat/energy. That external energy expenditure is necessary so as to create an imbalance that starts a flow of energy from ambient heat towards the cold spot. Once the flow is started you can extract some energy from it but you have to maintain the "load" or heat/energy sink by continuing to throw off more energy than is actually being extracted from the resulting flow of energy. The heat engine apparently running on ice cubes is not really running on ice cubes either. It is running by interrupting the flow between the ambient temperature (relative hot) and the colder ice. Heat flows from relative warm to relative cold. The energy is coming from the heat source not the heat sink. The heat source is ambient heat. --------------- I've been wanting to mention also that you guys have got me thinking, Mr Skeptic about the fact that expanding air would expand faster if it could also absorb some heat while doing so, and npts2020 that the heat being extracted from the displacer chamber might indeed expand the air creating some back pressure. I thought the solution might be to sandwich the turbine and the displacer chamber together, back to back or actually put the turbine INSIDE the displacer chamber down at the cold end. In this way your heat-sink would be where you want it, doing the job of extracting heat, and this heat being extracted would actually ADD POWER TO THE TURBINE by providing the air in the turbine with a heat source allowing the air to expand with even more force - not to mention eliminating a lot of unnecessary material - (i.e. the piping from the turbine to the bottom of the displacer chamber), as well as reclaiming some heat/energy that might otherwise be wasted.
  15. Right, so we are in agreement there. But this should be a very small power loss. I'm imagining that the displacer will take such little power that it could easily run on the power output from the turbine with power to spare. Are you familiar with the novelty item called "The Dippy Bird" ? It, in effect, uses a small evaporative cooling system to throw off heat resulting in a temperature differential which then makes it possible for this bird to operate as a little heat engine - running on ambient temperature air. What allows it to operate - indefinitely, I believe, is the fact that it continues to dissipate heat so as to maintain the temperature differential needed to keep it running. So long as it continues to rapidly throw off heat, it can continue to run. It must however throw off much more heat than the little amount of heat it manages to convert into kinetic energy. The poor bird's little wet beak, though, is a very poor refrigeration system which produces only a slight temperature differential. Nevertheless, it works - and keeps on working, converting ambient heat into kinetic energy. One has even been equipped with a small generator so that it could produce a few micro-amps of electricity. This engine utilizes the same principle. Find a way to throw off enough heat with some sort of refrigeration system, one that consumes very little power for its own operation, and it is possible to extract power from the resulting temperature differential with a heat engine. The "Dippy-Bird" is a kind of Hybrid, cooling system and heat engine in one unit. So is this. The only difference, really, is that this "Stirling Turbine" uses a much more powerful and efficient cooling system which creates a much greater temperature differential suggesting the possibility that a great deal more power might be generated than what could be had by evaporating water from a dime size piece of felt on a toy birds nose. In other words, there IS a temperature differential. Ummm.... Yes, but that is not what is happening here. I'm not sure what you mean here. In this case, after drawing energy from the gas via expansion through a turbo-expander, the resulting cold gas is utilized as the heat sink for your temperature differential in your compressor. There is another way, which is what is primarily being utilized here, That is, making the gas to do work. That all depends on the application. Again, that is only one application. In actual fact it both cools the gas and "recovers" or produces power at the same time. Not sure what you are getting at there. Yes, to a compressor. Generally a compressor is an enormous power hog. Lets say my little home compressor draws 3,000 watts. I'm guessing at that, only because it is always tripping a 30 Amp breaker. Freed from acting as a slave to the compressor, a turbine capable of running on the output air pressure of this compressor should then be able to produce about 300 watts. For me, that would be significant, as right now I am posting this message from a laptop being powered by a 45 watt solar panel, and this is adequate for most of my needs. (wireless laptop, lighting, radio, etc. for my camper). And it is a cloudy winter day that only lasts till nightfall. 300 watts, continuous 24/7 would spoil me rotten. Probably true. But whatever, that is hopefully not the case for this system. Rather, it may take less power to operate the displacer than what the turbine can produce. As for small things, so also for larger things. The little "Dippy Bird" works. It extracts ambient heat from the air to do work. Why not something using the same principle but more efficient at maintaining a temperature differential and capable of producing more than a milliamp of power ? LOL... You should have seen what happened to my buoyancy motor when I plunged it into a tank of water. Merged post follows: Consecutive posts merged I understand what you are saying here, but two things. 1. the cold air is running out through an insulated pipe to atmospheric pressure. The nozzle within the turbine contains compressed air at a higher pressure. I don't believe that there will be any problem with back pressure there. The problem as I see it is that the cold air, as it is being exhausted, will tend to cool and contract the air in front of it - drawing hot air back in through the system, but this will not result in back pressure. It will result in a vacuum, which if anything should cause the turbine to run faster as it would create a vacuum condition in front of the cold gas. The problem is that hot air being drawn in through the exhaust will "contaminate" the cold air with too much heat - loosing the temperature differential. The solution to this, I think, is to simply continue charging the system with an external source of compressed air until all of this indrawn hot air is completely evacuated. Since the exhaust pipe goes up and hot air rises and cold air falls, a condition should eventually be reached where the cold air has filled the entire exhaust pipe from top to bottom. In other words, this may require a very long time to "charge" the system and evacuate all of that hot air that will tend to draw backward into the system through the exhaust, but once all of that hot air is completely evacuated and there is a steady stream of cold dense air coming out the top of the exhaust, this should no longer be a problem. The cold air will tend to remain "pooled" in the pipe like water. As you mention, some sort of check valve may help, but I don't really think it will be necessary once the system is fully charged. If a check valve were used at startup, I'm afraid that the vacuum created in the exhaust tube would begin sucking too much air out of the turbine nozzle too quickly. On the other hand, such a vacuum condition might actually help, as if anything it might draw gas through the coils more quickly resulting in faster heating. Hard to say without trying it and seeing what happens. Perhaps some cold liquefied gas could be poured into the exhaust pipe at start up to get things in order. The greatest difficulty with this concept is, I think, getting it going. It will theoretically run on a temperature differential, but it may take some doing to get that temperature differential properly established. Once established, it shouldn't be difficult to maintain. The main problem for me, as far as designing this thing is... I don't know the math. Exactly what size pipes to use where to get the right temperatures... how much contraction or expansion is possible at what temperature differntials... How to balance the size of the displacer to the turbine size, how long and how many loops to put in the coils etc. I'm sure refrigerator manufacturers have engineers and mathematicians and such to figure all that out. I don't. Except by trial and error. If it seems worth pursuing, I suppose I could learn. I'm good at math, as far as algebra and trigonometry, but I've seen some of these thermodynamic equations and wouldn't no where to begin as far as trying to understand them. I imagine that these things would have to be established mathematically, or by a great deal of trial and error. Certainly not. If anything, my plan would be to build a conventional Stirling type displacer set up out of some old tin cans. Solder on a few short pieces of copper tubing with some old bicycle ball bearings for check valves. Put a balloon over the exhaust pipe and move the displacer up and down by hand with just a candle under the thing to start out with and see if such an arrangement can actually pump any air whatsoever. If a tin can "Stirling Compressor" can blow up a balloon... Maybe I'll try a bicycle tire next and see if it can blow that up... If such a "tin can" compressor can work, It might be worth putting a tank on the exhaust with a pressure gage and see what kind of pressure such a thing might be capable of building up. If things look good, I might then move on to building a little model Tesla "CD" type turbine... If the tin can displacer can't even blow up a balloon, well... The rest of the idea can be scraped, as everything is dependent upon this "much more efficient compressor" that can operate on a temperature differential. The temperature differential from a candle or some ice would serve as well as anything for testing purposes. And a tin can displacer is a simple enough thing to build. I used to do experiments though, as a kid, in my parents kitchen. Heating up a can on the stove and then putting the cap on and plunging it into some ice and watching if implode - as if a truck had just run over it. The expansion and contraction of air from a simple temperature change can be a powerful force. So I am not underestimating the potential of a small "tin can" model. Not until I actually build one and see what it can do anyway. P.S. I forgot to mention in regard to the following: The portion of the system being referred to here is only the cold air outlet of an "air-cycle" cooling system. The only difference it has from any open air-cycle refrigeration or air conditioning system currently in operation is the type of compressor that is delivering compressed air to the turbine, which has no bearing on the exhaust from the turbine as far as I can see. My point being, there are currently thousands upon thousands of such air cycle systems in operation as we speak, delivering cold air to jet airliner cabins, cold storage warehouses etc. In all the literature I've been able to locate and read regarding the operation of such systems, none have ever mentioned anything whatsoever about back pressure on the turbine bringing it to a halt or even slowing it down. Such systems DO WORK and currently ARE WORKING, so if this is any kind of problem it seems that air-cycle system manufacturers have found some means to overcome it. The only major problem often mentioned is ICE forming on the turbine blades due to the extremely low temperatures produced. These expansion turbines tend to ice up, especially during very humid weather. But as far as back pressure on the turbine,... as far as I'm aware this has never been a problem with any of these air-cycle systems, or expansion turbines in general, regardless of the application. I'm hoping that by using a bladeless turbine (or Tesla turbine) this ice problem might not be such a problem either. Ice can't get hung up on turbine blades if there are no turbine blades. I've seen some You Tube videos of Homemade model size Tesla turbines and they also seem to be very quiet. Almost silent in their operation, which in my mind, was one of the main drawbacks of this idea. The noise from a conventional Turbine would be intolerable. Tesla turbines seem to run as smooth as silk.
  16. It doesn't follow ? Maybe I'm reading it wrong somehow, but that seems to me to be what the references say. But if a Stirling engine's displacer is able to deliver more power to a piston than it takes for the piston to drive a crankshaft which in turn drives the displacer as well as producing work in the process, What do you mean it doesn't ? O.K. maybe it doesn't exactly "deliver" the power directly. It just controls the heat flow that makes the power available to drive the piston, itself and some external load... The power comes from the heat, but it only takes the displacer a minuscule amount of power to direct the flow of heat as compared with the resulting power output. Granted, I suppose. But I don't know what your point is there. If the turbine had a power input it would be driving the gas or compressing the gas. Either way the gas would heat up as the energy would be transfered to the gas. When the gas is driving the turbine the energy is being transfered to the turbine. It has to have an output, otherwise the gas wouldn't be doing any work and it wouldn't get cold. Not very cold anyway. The energy has to go somewhere. That is if you have a gas in a confined space or cylinder and you are drawing back the piston to lower the vacuum, or I suppose a turbine could also be used... if the turbine is sucking the gas up a tube or something. But if the turbine were sucking the gas up it would also be driving it out once the gas reached the turbine and then heat it back up in the process. What kind of "evaporation" are you talking about anyway ? How does a gas "evaporate" ? It's already a gas ! Right. and it gets even colder when it is made to do work at the same time. Well, I provided you with the one example you requested. Several examples and additional references actually. But maybe it won't work, who knows ? I just don't think it won't work for any of the reasons you have mentioned so far. An expansion turbine is driven or powered by the expanding gas. The gas is being shot through a nozzle into the turbine, sometimes at sonic or supersonic speed causing it to rotate at tens of thousands of RPMs in some cases. The turbo-expander is not creating any kind of vacuum to speed up any sort of "evaporation". Did you read the reference ? quote: "As the cooled gas pushes against the turbine blades, it makes the rod rotate" It says "The gas pushes against the turbine blades" not that the turbine blades push the gas" Every other reference says the same thing. The gas drives the turbine not vice versa and the turbine driven by the expanding gas outputs power. There is no reason to connect that power to the grid or anything when the power generated by the turbine can be used right on the spot to take the load off the compressor - usually coupled right to the same shaft as the compressor. But if you no longer wish to discuss this, I'll just thank you for the time and attention you have given to this. It is most appreciated. Thanks. Tom Merged post follows: Consecutive posts merged Who says it wouldn't ? I suppose it would, if encased in asbestos. This thing is basically a refrigeration system. You may be aware that some refrigerators operate on a heat source. Gas refrigerators for example. It took me a long time for me to understand that myself - how does a hot gas flame make ice in an ice box ???? It makes no sense. Add heat and get cold ??? impossible ! Well, you use the heat to compress a gas. Under pressure, the gas heats up ABOVE AMBIENT TEMPERATURE. You can now use ambient temperature air to cool the pressurized gas. The gas is trapped in a narrow hollow tubular coil and you just allow convection to cool the coil. Now when you allow the gas to expand into a larger tube, after having all that heat driven off, upon expanding to its former pressure and volume the gas tries to get the heat back, but now it is in a different area, now instead of being out in ambient temperature air it is in some pipe in a little insulated freezer box, but it draws as much heat out of the box as it can before moving along to another tube where it is re-heated by the flame. Why doesn't the air inside a Gas freezer eventually return to ambient temperature? Especially when its input source of energy is a blue hot flame ? Well, here your "sink" for your displacer chamber is the constant supply of air from the turbine which has had the heat removed from it by being compressed, cooled, allowed to expand and made to do work. This cold air constantly flows through the tubing in the displacer chamber which constitutes your heat sink. Any heat that this cold air picks up is then evacuated from the system back to the atmosphere where it heats up again. I've just described how it does. at least in theory. The "pumping" of "great volumes of water, air or some other coolant through the sink." is accomplished by channeling the flow of cold air coming out from the turbine through your heat sink. which in this case is the tubing in the bottom of the displacer chamber. But it isn't being "pumped" exactly. More like just being pushed along by the additional cold air coming out of the turbine behind it. There is no additional energy requirement for this "pumping", in fact, the turbine itself is being driven. The only real energy input into this system other than the hot air coming from the atmosphere is whatever it takes to move the displacer, which is insignificant compared with the power output from the turbine. Theoretically anyway.
  17. I've read about many different applications. Generally speaking though, in most applications the turbo-expander is coupled to the compressor on the same shaft so that the power output from the turbine is used to reduce the load on the compressor. Like I said previously, all this is contingent upon the efficiency of the compressor. Could a Stirling type displacer chamber actually compress air at all ? I don't really know. And at what kind of pressure and volume. I don't know that either. And at what efficiency... But if a Stirling engine's displacer is able to deliver more power to a piston than it takes for the piston to drive a crankshaft which in turn drives the displacer as well as producing work in the process, I don't see why the same would not hold true for the same displacer being used to drive a turbine and having some of the power produced by the turbine in turn operating the displacer as well as doing work. You have eliminated a lot of the friction by eliminating the piston and crankshaft and rocker arms and what not and the turbine is supposed to be more efficient than a piston... We are just moving heat around with this system and from what I understand about heat-pumps, it requires less energy input for the heat pump to simply transport heat to where it is needed than what it would take to provide the same amount of heat by some other method. But all that is beside the point regarding the Turbo-expander. Given a supply of compressed air a turbo-expander does produce a power output. It has to, as that is its function and the reason why the things are being used: To cool gases - to draw off the energy to get the gas cold enough for refrigeration or cold enough to liquefy. To do that it has to have a load of some kind, it has to be producing power so as to convert the heat energy in the gas into another form so that the gas gets cold. In most cases the gas is not pre-cooled, but in other cases it is, so as to get even lower temperatures, like in cryogenics or liquefaction of gases. In most other applications pre-cooling is not necessary. Whether it could produce enough cold to supply sufficient amounts of cold air to the displacer while still producing a surplus power output at the generator is a different issue. Bottom line in regard to the turbo-expander is, it can and does produce both a power output and remove heat. It has to have a power output in order to remove heat. That is its usual function. This is particularly true in refrigeration and in the liquefaction of gases or other applications where extremely cold temperatures are needed where excess heat constitutes an unwanted "waste" product. In such applications the turbine is used to get rid of the unwanted heat very rapidly and efficiently by converting it into electricity and operating some redundant load just to carry away the excess heat. That is what is needed here as well. As you say,... if you are going to try to run something on ambient air temperatures, you might as well just toss it in a furnace... Well, as I said earlier. This might be possible if you can find some way of getting rid of all the excess heat. Get rid of the heat, dump it somewhere far away. Create a cold spot and then keep that cold spot well insulated against any kind of unnecessary heat intrusion. If you can do that, and keep doing it fast enough and efficiently enough then you have a temperature differential to run your engine - drawing its energy from the surrounding heat of the "furnace" just a little at a time, and using just some of that heat to export the excess heat that might inadvertently find its way into the system. This is what the expansion turbine does. It is an efficient means of exporting excess heat. The Stirling displacer set up is an efficient means of utilizing the resulting temperature differential. Both the Stirling compressor unit AND the turbine are utilizing heat. The displacer uses some of the heat from the little bit of air that is let in to compress more air to run the turbine. The turbine uses what heat is left in the cooled air coming from the displacer to produce electricity, any additional excess heat can be removed by exposing some of the heating coils to cooler ambient temperatures at some point or by passing the coils through the cold exhaust. Once you use up all that heat energy you are left with very cold air, which is just the absence of heat. Can the two working together get rid of the excess heat fast enough to keep each other operating ? I'm not sure about that, but if they can, then much of the resulting "waste product" is usable electricity from the turbo-generator. Naturally all this stuff would have to be balanced out and well insulated to maintain constant specified temperatures. Personally, I'm thinking that all that is really needed to make this work is a lot of good insulation to prevent heat from infiltrating the system, Then your intake pipe coming from the outside hot air "furnace" is like a fuel line. By converting the heat into electricity you can dump it far away somewhere through the electric lines powering some load - like the utility grid. You use the cold produced by the turbo-generator to keep your space air conditioned. You can also dump some of the excess heat by exposing a portion of the heating coils (still above ambient temperature) to ambient temperature air and to the cold air exhaust after you have used as much heat as you need to operate the displacer/compressor. You don't want to leave any excess heat lying around as this would eventually reduce your temperature differential - you need to get rid of all the excess heat you don't use. As far as the way the Turboexpander operates, just put "Turboexpander" into a search engine. or "liquefaction of gasses" or "air cycle refrigeration" or "air cycle machine" or "ACM" or "expansion turbine" Here is a website that explains it fairly simply: http://www.scienceclarified.com/Ga-He/Gases-Liquefaction-of.html Regarding the use of the turbine for cooling the gas to temperatures cold enough for liquefaction: ---------------- "Methods of liquefaction Making a gas work against an external force. ...The liquefaction of a true gas, therefore, requires two steps. First, the gas is cooled. Next, the cool gas is forced to do work against some external system. It might, for example, be driven through a small turbine... As the cooled gas pushes against the turbine blades, it makes the rod rotate. At the same time, the gas loses energy, and its temperature drops even further. Eventually the gas loses enough energy for it to change to a liquid." http://www.scienceclarified.com/Ga-He/Gases-Liquefaction-of.html ------------------------- This particular article doesn't mention that there has to be a load on the turbine, but I've read elsewhere that this is necessary. The turbine can't just freewheel. Here is a You Tube video about the Air cycle system that talks about reducing the temperature of a gas by "making the gas to do work in an isentropic process". I don't think I could provide you with any existing scenario that exactly matches what I'm trying to do here because as far as I'm aware nobody has ever considered this particular application mainly because there has never been any such thing as an efficient compressor, or any compressor for that matter that runs on a temperature differential. Most compressors draw so much power that the output of the turbine is not used for anything more than to reduce the load on the compressor. The situation is the same for the expansion turbines used by industry. Generally, whatever process is going on usually requires a compressor of some sort and the power output from the turbine is used for nothing more than to reduce the load on the compressor, but there is a power output from the turbine - but with this system the energy needed to move the displacer is probably only a fraction of the energy that the turbine has to expend in overcoming the friction of its own bearings, no less helping to power a compressor. I mean, maybe it can't work because there is too much back pressure or the turbine cant produce enough cold air or some other reason, like the "Stirling compressor" just won't work the way I imagine it might, but I don't think that there is any problem as far as the turbine simultaneously removing heat and doing work at the same time... that is what it does. That is why it is being used in countless applications right now, and has been for many years already. That is a given. This Wiki article gives many examples: http://en.wikipedia.org/wiki/Turboexpander
  18. Not exactly. I'm not sure what you are talking about. In the turbine ? It is not being allowed to warm to expand. The expansion takes place without any transfer of heat. The gas expands on its own becoming more diffused. As the molecules are using their own energy to carry out the expansion the gas gets colder not warmer. No, actually, the little buggers have a lot more heat energy to give up than you might imagine. All the way down to near absolute zero. If anything you are actually gaining energy as the expanding molecules impact the turbine. I don't mean to be disagreeable, but I believe you are very mistaken. The use of expansion turbines to cool gases is a fairly obscure topic. If the turbine is insulated against heat intrusion from the environment the gas expands anyway drawing upon its own internal energy to do so and gets colder in the process. If there is any heating up by friction it is minuscule as compared with the internal energy given up by the gas molecules to do the work of turning the turbine against the load on the turbine load. In giving up this energy the Gas gets extremely cold. In this case you isolate the turbine from external heat sources so that the gas is forced to use its own internal energy to Carry out the expansion through the turbine - doing work in the process. The reason being that you want the gas to get very cold so as to be able to utilize that cold for your temperature differential when the air makes its way back through the displacer chamber as well as to further pre-cool the air before entering the turbine. If you powered the turbine, rather than drawing power from it, the gas, if anything would have less work to do - since it no longer has to do any work to move the turbine out of its way to expand and therefor you would draw less energy from the gas and you would get less cooling of the gas. I don't believe I have anything backward, but I think that you may need to brush up on how an expansion turbine is used to cool various gasses. This has innumerable applications for refining of natural gas, liquefaction of gases, cryogenics, refrigeration, etc. Turbines are used in this manner to cool gases every day, to liquefy oxygen to fill oxygen tanks, cool aircraft cabins, to liquefy propane so it can be put into tanks to heat peoples homes etc. etc. I've read dozens of articles on the subject, watched educational videos, read dozens of websites and looked in numerous books and encyclopedias about the use of turbines for cooling in refrigeration, the refinement of petroleum, and various other low temperature processes. I don't think I'm wrong about how this works. It sounds unbelievable, like the heat just "disappears" as the gas passes through the turbine, but it doesn't just disappear, it is CONVERTED into another form of energy to do work. The energy to do the work of turning the turbine comes from the expansion of the gas itself and and this causes the gas to become cold. Apparently it wants to expand so badly that it is willing to give up its own internal energy to do so even if it has to loose energy and push a turbine out of the way in the process.
  19. Hmmm... I am aware of these points. No problem there, except that I'm beginning to wonder if you have looked at the diagrams of my theoretical "Stirling Turbine" idea. Two different versions here: http://prc_projects.tripod.com/stirling_air_turbine.html http://prc_projects.tripod.com/stirling_air_turbine_2.html This is a kind of hybrid heat engine AND air-cycle heat pump combined with all redundant moving parts eliminated. As you say: "A heat pump creates a temperature differential via input of energy. A heat engine uses a temperature differential to output energy. They are opposites in a sense" This is correct. But this engine is BOTH. However the "Heat Engine" has been stripped down to the bare essential element. It's "displacer chamber" with only one moving part that bears no load and encounters very little friction in its operation. It also doubles as the "compressor" for your air-cycle cooling system. A "compressor" which still, bears no load and encounters no friction. The only other moving part is the turbine for your air-cycle heat pump which also operates with relatively little friction. By combining these "opposites" at least two major sources of energy drain on both systems have been virtually eliminated in their entirety. The compressor for your heat exchanger and the entire mechanical apparatus of your heat engine - no piston, crankshaft, gears etc. I'm not certain how much you know about the Stirling engine,... but I'm assuming that you know that what allows it to operate and produce power is the fact that it takes LESS power to move the displacer than it takes to drive the piston with the resulting pressure changes. By eliminating the piston and replacing it with a more efficient turbine and using check valves to convert the alternating pressure changes into a steady flow, the same principle should hold true i.e. it takes less energy to move the displacer than what we can gain back at the turbine. Your turbine is now a replacement for the piston in your heat engine and has therefore become your power producing unit which theoretically, like the piston in a Stirling Engine can produce more power than it took to compress the air to run it... and it is MORE EFFICIENT than a piston. It also doubles as the primary element in your air-cycle refrigeration system... Which in a normal air-cycle system would be an energy drain on the air-cycle system. This former "energy drain" that normally would have also needed a compressor to run it, has now, with this configuration, become a power producing element of the system, replacing your former power producing piston in your heat engine. So, given an initial temperature differential you can now theoretically get more power from the turbine than what would be needed to move your displacer to keep compressing air to keep powering the turbine. As long as a temperature differential can be maintained, you are now getting more power out than what you put in. Incidentally, an air-cycle system heat pump produces an extreme temperature differential. A temperature differential more extreme than what would probably be needed to get the system started... and that, without any additional energy input. By combining functions, no other elements are needed - other then a steady supply of heat. These points are well understood, but they do not apply to this particular configuration. In this case, the turbine does not compress the gas, the gas is decompressed through it. The turbine is your power producing element not a power consuming element. The gas is compressed by the action of the displacer. I'm sure you are aware that any air conditioner, refrigerator, freezer, and any other heat exchanger including the air-cycle system with a turbine function quite normally while immersed in this "furnace" we call an atmosphere. Theoretically, they could all be run on the energy output from a Stirling Engine running on the same ambient temperature air if the Stirling engine were made to run on ice to provide it with a temperature differential.... and the air-cycle system not only produces temperatures potentially much colder than ice, it also produces heat much hotter than ambient temperatures. Initially, to get things started you would have to "charge" the system with compressed air from an outside energy source - like an air compressor. This air would be pumped into the pipes at some point near where the pressure gage in the second illustration is located. The compressed air, as it begins to travel through the system would first encounter the narrow "heating element" in the top of the displacer chamber and begin giving up some heat, initiating some temperature differential within the displacer chamber. The air would then continue traveling through some additional coils until it reached the turbine. The compressed air would exit the nozzle into the turbine and begin turning the turbine rotor. When the turbine got up to speed, you could then apply a load to the turbine. The air expanding through the turbine would be colder than it was upon entering the turbine. This colder air would be piped (The pipes insulated against the heat of the ambient air) back to the displacer chamber to begin providing the cold element of your temperature differential. The cold air would then continue traveling - exiting the pipes at the bottom of the displacer chamber and the cold air would be passed across the previously mentioned "additional coils". This would begin cooling the compressed air inside these coils before the compressed air could reach the turbine - pre-cooling the air before it enters the turbine and thus making the air exiting the turbine that much colder. The cool air then exits the system back to atmosphere. This would continue until a substantial temperature differential is established within the displacer chamber and we can begin running the displacer off of a fraction of the electrical energy being produced by the turbo-generator. An additional remote load would also have to be maintained on the turbine. Once the displacer begins its motion - converting the established temperature differential into a pressure differential the external source of compressed air can be removed. As the turbine is putting out more energy than it take to provide action to the displacer the system should now be able to maintain its own temperature differential and keep running. In fact, the temperature differential should INCREASE as it begins to run on its own as the heat used by the displacer unit to compress the incoming air is being recirculated and there is a continuous supply of heat provided by the fresh incoming air being supplied to it. So rather than loosing the pressure and temperature differentials provided by the initial "charging" of the system the temperature and pressure differentials should increase incrementally as the system operates. Theoretically, some regulating mechanisms would need to be introduced to prevent a run away condition and keep the pressure and temperature differentials at some specified levels. As I understand it. For a gas, heat energy and kinetic energy are essentially the same thing. When heat is added to a gas, the molecules become more active and therefore need more room to move around, i.e. the gas tries to expand. If the gas is forced into a small confined area where it cannot move around as freely it is forced to give up heat. etc. With a gas, heat energy and kinetic energy are closely related if not identical. I don't think this has any relevance to this system except perhaps within the "displacer" unit where the temperature differential between the heating and cooling coils is used along with the action of the check valves to convert the alternating expansion and contraction of the air into a direct flow for your "compressor". I do not "think that the turbine or piston will get cold in and of itself". Are you at all familiar with the air-cycle system cooling process ? As I understand it, the air passing through the turbine gets extremely cold due to the expanding air being made to do work. There is no "flow" of "heat" to a "heat sink". There is, however a flow of energy out of the system. As this energy is being taken from the "kinetic" energy of the gas which is driving the turbine - the gas becomes less energetic and its expansion is reversed. The gas gives up much of its energy but has no way of getting it back immediately, assuming that the turbine is insulated from external heat sources. It is therefore ready to absorb more energy i.e. it is extremely cold, but it is unable to do so until it reaches the displacer chamber, where it is used to provide your temperature differential but will not ultimately gain back the energy lost until it is evacuated from the system back into the atmosphere where it can heat up again. Eventually, after it makes a few trips around the world it may reenter the system with a fresh supply of heat to be utilized by the system. Of course, which is why I made the distinction. No, it is not a "heat sink". Not in the conventional sense anyway. But in this system it IS an ENERGY SINK and for a gas, that amounts to the same thing. Technically, I would say that the heat is CONVERTED into another form of energy - ultimately, it is converted into electricity by the turbo-generator and exits the system. If this were connected to the grid, the heat might re-emerge as radiant heat in a toaster or electric range somewhere to help cook somebody's breakfast - be released back into the atmosphere and eventually find its way back in the vicinity of the "Stirling Turbine" and be sucked in where its heat energy could once again be utilized. If you include the atmosphere as part of the system this is really a "closed" system with the atmosphere acting as your heat exchanger where the gas is expanded and allowed to recapture some heat before being drawn back in - maybe, someday, if the system is in operation long enough. I'm not sure what you are describing in the above, but it does not sound like the action of any Stirling Engine that I'm aware of and certainly does not apply to this system in every particular. Taking it step by step as it applies or otherwise to this system: 1) Heat source heats up fluid maintaining constant volume, which pressurizes it. This applies, the hot end of the displacer chamber heats up the air inside it when the displacer moves down forcing the air up against the "heating" coils. 2) Pressure differential is used to drive a piston or turbine. In this system, this does not happen immediately. Rather, the air is allowed to expand through a port with a check valve as it reaches maximum pressure. Once it exits it is trapped under pressure behind the check valve. Only a fraction of the energy is transferred to the the turbine; the rest is waste heat. In this system, much of this "waste heat" in the gas is recirculated through a narrow coil within the displacer chamber where under pressure and passing through a confined space it is made to give back much of this "waste heat" so as to help maintain your temperature differential - before it ever reaches the turbine. By the time the compressed air reaches the turbine it should be below ambient temperatures while still under pressure. This is much like a gas liquefaction process where gas is simultaneously compressed and cooled until it becomes so dense that it liquefies. This system does not go to that extreme of liquefying the air but it is going in that direction long before the gas reached the turbine. What powers the turbine is NOT the heat of the compressed gas, which has already been removed but its violent expansion once it is injected into the turbine through a very narrow nozzle (like a propane torch nozzle) where it escapes its confinement compressed and cooled within a narrow tube. This is not quite a change of state, but the principle is similar,... like the liquid propane escaping the bottle through the torch nozzle where it can now expand back into a gas. Temperature and pressure have little of nothing to do with this expansion, it is more like a change of state where the cooled and compressed gas is liberated and expands simply because it now has room to do so. In the process it now is looking to absorb heat but it is not able to do so until it returns to the displacer chamber. i.e. there is no, or very little "waste heat". 3) The gas is allowed to cool at the heat sink at constant pressure, which reduces its volume. The cold gas leaving the turbine has already expanded to atmospheric pressure. There is no "Heat Sink" where the gas is "allowed to cool" it is already cold. This cold gas itself is used as your heat sink as it is piped through the displacer chamber to provide the cold side of your temperature differential to the displacer chamber which operates like a "heat engine" but functions as your "compressor" for the Air-Cycle System. The volume of the gas is not "reduced". If anything it is still expanding after leaving the turbine and still trying to reclaim its lost heat until it is evacuated back to the atmosphere. 4) The cooled, reduced volume fluid is introduced into the heat source. Sort of. But the "fluid" (Air) is not reduced in volume, except perhaps on a molecular level, but has been exposed to atmospheric pressures. The "heat source" is the atmosphere into which the air is eventually released and can reclaim the heat it lost while passing through the system. If a pump is needed to force it in, No pump is needed. The air escapes to the atmosphere quite willingly I should think. this will require less work than gained in step 2, because the pressure is the same but the volume smaller. It will require no, or very little "work" whatsoever, other than perhaps a bit of back pressure against the air exiting the turbine behind it... which is helping to push it along. But again, the turbine is not a power consuming unit, it is a power producing unit. It does not "pump" the gas. It simply provides an escape route back to atmosphere through the orifice in the turbine nozzle and extracts energy from the gas in the process as it is attempting to escape and expand and return back to the atmosphere. That this will require "less work" is something of an understatement. Rather than needing a pump to force the gas to the heat source the gas quite willingly escapes to the "heat source" and energy is extracted from it in the process by only allowing it to escape back to the atmosphere if it first does some work for us at the turbine. How whatever kind of heat engine you are describing operates, this applies very little to this hybrid air-cycle system/heat engine hybrid thing that for want of a better name I'm calling a "Stirling Turbine" for the moment. I believe that it can very well operate within this "furnace" if you can initiate a temperature differential and then insulate and maintain it against unwanted heat gains and losses to or from the atmosphere. A Stirling Engine could "run on ice" inside a furnace if your block of ice is kept well insulated and if you can eject unwanted excess heat by converting it into electricity where it can be dissipated at some remote location. Especially if you can find a way to make your "Stirling Engine" double as an "ice maker". My illustrations do not depict any insulation around this thing, but certainly it would have to be well insulated against various unwanted heat gains and losses at various junctures throughout the system. I have my own doubts about all this working as intended, but as far as I can see your criticisms don't seem to apply or are irrelevant to this particular system. This is not just a heat engine nor is it just an air-cycle cooling system it is a hybrid combination of both which has allowed for the elimination of all the "energy hog" components generally present in such systems. All redundant moving parts have been eliminated, there is very little friction anywhere within the system. The only energy drain on the system is minuscule (the operation of the displacer) and the potential energy output is virtually unlimited. If a block of ice were well insulated, I imagine that a well built Stirling Engine could use it for it's temperature differential almost indefinitely as the heat passing through the engine on its way to the ice is interrupted and energy is extracted and the heat itself is "regenerated" so very little of it ever actually completes its path towards the ice. If the engine can double as an "ice-maker", with no additional energy input, why could it not maintain this temperature differential indefinitely while continuing to output energy which it has drawn from the atmosphere and converted from heat energy into kinetic energy ? Merged post follows: Consecutive posts merged This point regarding the air getting cold as it passes into and is made to do work through the turbine seems to be the main point of contention. There is another way that a turbine can be turned which is commonly used in refrigeration and gas liquefaction processes, especially where very low temperatures are required. Technically the gas being "injected" into the turbine in this engine is not really being injected under any tremendous amount of pressure. First it has been compressed in the displacer chamber, then it goes through several stages of cooling. This cooling helps to contract the air reducing its volume so that more and more air can be compressed into the same narrow tube. By the time this gas reaches the turbine it has cooled and contracted so much that it still is not under all that great a pressure. When it is released into the turbine, it is NOT the little pressure behind it that turns the turbine. The gas virtually drips out of the nozzle as a liquid so-to-speak. Though it is very unlikely that the gas will actually be liquefied at this point it is theoretically possible. My point is that there is not a lot of pressure behind it. Not enough to actually turn the turbine. The energy to turn the turbine comes mostly from the gas itself. The gas expands on its own. This is the reverse of what took place earlier when the gas was compressed and forced to give up heat. Just as air got hot under compression it gets cold during decompression. The ENERGY for this violent expansion has to come from the air molecules themselves. As a result, the pre-cooled air entering the turbine cools down even more as it expands. But as it expands through the turbine it is also made to do work. As the pre-cooled gas, now even colder due to using its own INTERNAL molecular energy to expand itself works against the turbine blades, it loses even more energy and its temperature drops further. This process of turbo-expansion can result in such extremely cold temperatures it is commonly used in the liquefaction of gases or in cryogenic freezers. If this process were repeated the gas could loose enough energy to cause it to liquefy. I don't think that this little engine would get anywhere near producing that kind of cold but it is not only theoretically possible, this is how gasses are presently being liquefied by industries all over the world. i.e. by turbo-expansion of a pre-cooled compressed gas. Your insistence that no change of temperature takes place inside a turbine is only applicable to - say, something like a water driven turbine or a wind turbine not a turbo-expander where a gas is giving up its own internal molecular energy to do the work of expanding and turning the turbine.
  20. I see your point: i.e. the atmosphere is like a giant furnace heated by the sun. However, in this case, the turbine is not running on ambient heat exactly. At least not directly. As you say "A heat engine creates a pressure differential by using a temperature differential" The displacer chamber (basically a modified heat engine, at least in principle) uses a temperature differential to create the pressure differential which runs the turbine. (theoretically of course) I think you just answered your own question. The next question I suppose would be, where does the "heat engine" get the temperature differential ? (so as to create the pressure differential to run the turbine) This is true in the majority of cases where a turbine is used, yes, but I believe the situation is a little different when a turbine is used in an air-cycle refrigeration system. In an air cycle system, the pressurized air is injected into the turbine while the turbine is under a load. Before entering the turbine the air is not just compressed but it is also cooled by compressing it through a narrow duct or tube where it gives up heat prior to entering the turbine. When it (reatively cold air) is injected under pressure into the turbine it expands violently and is simultaneously made to do work since the turbine is under a load - turning a generator to power something else remote from the system. In many air cycle systems the turbine is just given some redundant work to do, like powering a big electric fan that serves no other purpose other than to draw energy off the turbine so that it is under a load as the air is expanded through it to draw more energy out of the air so as to furter cool the air for refrigeration or air conditioning purposes. Where does this energy to run this remote fan (or other load) come from ? The only place it can come from is from the expanding air that is driving the turbine and the only kind of energy the air has to give up is its heat energy. This only works when the turbine is under a load (made to do work). if the air is expanded trough a turbine which is simply freewheeling without a load (not doing any work) then yes, there would be no significant energy or heat loss, though the air would become a little colder due to being allowed to expand, but the cold produced due to simple expansion is relatively insignificant as the actual energy contained in the air would not change, it would just be more diffuse. Put the turbine under a load however and the energy level in the air has to drop as this energy is ultimately leaving the system and therefore the temperature of the air passing through the turbine must also drop significantly over and above the temperature drop due to simple expansion alone. You do not get frost forming on an air tool if you just run the air tool without a load. The simple expansion of the air through the turbine in the air tool does not produce enough cold to form frost. You only get frost on an air tool when it is actually doing work as the heat energy in the expanding air while expanding through a turbine under a load is being converted into kinetic energy to do the work - such as removing lug nuts or tightening down some head bolts. Except a load and something to supply the working fluid (in this case, compressed air). The energetic air molecules expanding through a turbine while under a load, impact the turbine blades and transfer their energy to the turbine (to power the load) becoming less energetic. This translates into heat loss. Why? because heat is the only form of energy that a gas has to give up. Normally I would agree. But what I am using to compress the air is not a conventional air compressor. The air is compressed using the Stirling principle utilizing the temperature differential that results from the ice cold air leaving the turbine which has become very cold as a result of being made to do work while it is trying to expand. That very cold air from the turbine under a load and ambient air alone could provide some temperature differential. but I'm also (theoretically) removing some heat from the compressed air before it reaches the turbine and adding that heat to the hot end of the displacer chamber to increase the temperature differential in the displacer chamber where the air is being compressed. In this case, the heat source is the atmosphere. That furnace you were talking about. Once the air exits the system it is returned to the atmosphere where it can reabsorb more heat. Fresh warm air is drawn back in. If it expands in the atmosphere, this is irrelevant. The atmosphere is the low end of your pressure differential. Right. Sort of. As the air is trying to expand through the turbine (under a load) it impacts the turbine blades gives up some of its energy - gets colder and contracts before leaving the turbine housing. Normally, or in most applications. In this case I think that the heat energy is being taken from the air to do work, this heat energy in the air is being converted into kinetic energy to do work, your "heat sink" is the point at which the air molecules impact the turbine blades transferring their energy to the turbine, which is what turns the turbine and allows it to do work. The air molecules become less energetic at that point. For a gas, "less energetic" translates into "colder". So the turbine, in this scenario, is not "between" the heat source and the heat sink. It IS between high pressure compressed air and relatively low pressure atmospheric air, but the transfer of "heat" energy into kinetic energy is taking place on a molecular level at the point where the air molecules impact the turbine blades - molecule by molecule. Actually the "heat" in the air IS kinetic energy on a molecular level, so as the air molecules give up their kinetic energy to the turbine this translates into a drop in air temperature. As these same air molecules are leaving the turbine they are "hungry" to get back that energy that they lost, i.e. the air is now "cold" - able to draw in heat. I think there is some confusion here between pressure differential and temperature differential. The air under pressure enters the turbine through a nozzle where it is expanded to atmospheric pressure as it passes through and leaves the turbine. Hmmm... Makes no difference really. When air or other gas is made to do work it's temperature drops in proportion to how much work it does. Doesn't matter if that work is transfered by means of a piston or a turbine - the air gets colder either way. The only difference is that a turbine is generally much more efficient resulting in colder temperatures. The temperature of the expanding hot air pushing a piston in a heat engine also drops as a result of being made to do work (not just due to expansion) which helps to maintain the temperature differential. In an efficient (I mean ideal) Stirling engine, the heat from the hot side of the displacer chamber would never really reach the cold side of the chamber as the heat in the expanding air is converted into kinetic energy to do work as the expanding air pushes the piston. A Stirling engine actually runs cooler under a load. Without a load the temperature differential would tend to equalize and the engine would loose power or "overheat". Without doing work to convert the heat into another form of energy the heat would eventually creep to the cold end and the temperature differential would be lost. Same principle. The turbine is just potentially more efficient at converting the kinetic/heat energy in the air into practical work, therefore the turbine is better for making the cold air which is needed for this application to run the "air compressor" to compress more air to run the turbine to make more cold to keep the "compressor" running. All of this is contingent on the theory that a Stirling type "displacer chamber" can be converted into an "air compressor" by eliminating the piston and replacing it with a couple of check valves. In other words, the big question is - can you run an air compressor on a temperature differential with virtually no additional energy input other than heat ? Will the air actually expand out through one check valve and be drawn into the chamber through the other check valve with nothing more than a feather weight displacer bobbing up and down inside the chamber, its movement consuming a relatively insignificant amount of energy. Is a "Stirling compressor" possible ? Which is the heart of this system. If that is possible, then the pressure differential produced should be able to run the turbine (or at least try for a while) which could then produce the temperature differential (theoretically) needed to continue compressing air to continue running the turbine etc.. The "waste" product of this system would then be the energy used to power the load on the turbine... i.e. usable energy exiting the system. This is not energy from nothing or "perpetual motion". The solar heat energy in this "furnace" we call an atmosphere would be so-to-speak "wrung out" of the air and converted into a usable form leaving behind it a cold spot for your temperature differential. This will only continue (if it ever gets started) so long as the excess energy is being drawn off by the attached load on the turbine. In effect, the remote load on the turbine is your "heat" sink.
  21. Right What kind of "differential" are you referring to here ? Pressure differential or temperature differential ? A "vacuum" ? The air isn't drawn through the turbine exactly. It is pressurized above atmospheric pressure and injected into the turbine through a nozzle. In a sense, I guess you could say that the atmosphere is your "vacuum". At least a partial one as compared to the air under pressure. Same as with an air tool. The air is drawn in from the atmosphere and compressed and then decompressed or expanded through the turbine back to the atmosphere. My idea does not use a motor to compress the air. It uses the temperature differential created by the "air cycle system" heat exchanger. When air is heated it expands and the same air contracts when it is cooled. A Stirling engine uses this principle to drive a piston. The "displacer" in a Stirling engine drives air back and forth against the top and bottom of the displacer chamber, one end of the chamber is hotter than the other so the air alternately expands - creating pressure, then it is driven to the other end where it cools and contracts - creating a partial vacuum. This expansion and contraction drives the piston in a Stirling engine. At first I was working on having a Stirling engine drive a compressor, but I figured, why use the pressure differential in a Stirling engine to drive a piston to turn a crankshaft to turn a pulley to drive a belt to turn another pulley to drive another crankshaft in the compressor to drive a piston to compress air and trap it behind a check valve to get pressurized air to have a pressure differential to drive the turbine ? I just eliminated all those redundant moving parts and put some check valves in the displacer chamber to make a kind of direct "Stirling compressor" out of a Stirling type displacer chamber. You get the same, (or possibly greater) pressure differential with just one moving part and very little friction. It takes very little energy to move a displacer, much much less energy than what you would theoretically get back by using this principle to convert some of the available heat in the atmosphere into pressurized air. In this concept, as the air is driven back and forth by the displacer - causing it to alternately heat and expand then cool and contract, first the expanding air, instead of driving a piston some of the air is allowed to simply escape through a port where it is trapped behind a check valve. Then as the displacer moves causing the remaining air to impact the cold end of the chamber and lose heat and contract a vacuum is created which draws in more air which is trapped in the displacer chamber behind another check valve. In other words, you have an air pump which operates on a temperature differential to create a pressure differential. You could think of the check valves as acting like a set of diodes in an electrical circuit used to convert alternating current into direct current. The check valves convert the alternating pressure in the displacer chamber into direct pressure to run the turbine. (theoretically). This is difficult to visualize because the air is invisible. It would appear that the "displacer" is just moving up and down in an empty chamber, not doing anything, however, when the air hits the hot end of a displacer chamber it expands explosively in a Stirling engine driving a piston with enough force to drive the engine. Instead of using this expanding air to drive a piston I'm just letting some of the air escape through a port where it is trapped behind a check valve. It's only escape route back to atmosphere is then through the turbine. Before it reaches the turbine, however, it must pass through a narrow tube in the displacer chamber where it gives off some heat - similar to how electricity gives off heat when passed through a thin wire - due to the resistance. With a gas passing through a narrow tube your resistance comes from the tendency of the air to cling to the inner wall of the tube converting the kinetic energy of the moving pressurized air into heat to heat the top of your displacer chamber and increase the temperature differential within the displacer chamber. The remaining heat is extracted by the turbine to do work (run an electrical generator) causing the air to become very cold. This cold air is then sent through another set of coils in the bottom of the displacer chamber before being evacuated back to the atmosphere. Merged post follows: Consecutive posts merged Ummm... I don't think you would get it to do much work that way. That's like saying, why not throw a car engine into a furnace. Now you're getting the idea! That's like saying why not just run a car engine without gasoline. "The rest of the contraption" as you say, is your "fuel" delivery system. It is what compresses the air to run the turbine. I think you thunk correctly. If you consider compressed air to be a "fluid". More like a gas I think. Technically, this is an "expansion turbine" as it uses expanding gas (in this case, compressed air released through a nozzle) to drive it. The turbine, in this case, is not driven by a temperature differential, it is driven by a pressure differential. Compressed air in, expanded air out. In this case, the air is compressed by the expanding air in the displacer chamber where it is then trapped behind a check valve. Since the air is working against itself, instead of the heat/kinetic energy in the air being lost to work against a piston the energy in the air used to compress more air is conserved (transfered air to air) until it reaches the turbine. (except for some that is used to heat the hot end of your displacer chamber, but this heat/energy too is recirculated back into the system)
  22. In an Air-Cycle system the turbine doesn't get hot, it gets cold. One of the problems encountered with an air-cycle system is ICE forming on the turbine blades. Usually this means that moisture must be removed from the system prior to entering the turbine, but I'm hoping that by using a Tesla Turbine (bladeless turbine) this will not be a problem as ice would have a difficult time sticking to smooth disks (hopefully). The turbine doesn't get hot. The Heat energy in the compressed air powering the turbine is CONVERTED into "pure" kinetic energy. As I'm sure you are aware, virtually the only energy available to a gas is in the form of "heat" (actually the kinetic energy of the air molecules) so when the gas is made to do work, such as turning a turbine or pushing a piston in a hot air engine, the heat energy is converted into kinetic energy (the motion of the turbine or piston) and the air expanding through and then exiting the turbine then tries to recapture that lost heat energy (i.e. the air gets extremely "cold"), similar to how a gas in the expansion phase of a refrigeration system seeks to recapture lost heat i.e. gets "cold". "Heat" is partly potential energy and partly kinetic energy. In a gas it consist almost entirely of the kinetic energy of the gas molecules. A gas, expanding through a turbine loses its kinetic/heat energy to the turbine and gets very cold - potentially it can drop to near cryogenic temperatures, but this does not make the turbine hot as the "Heat" has been converted to another form. If the turbine is turning a generator, then the "heat" has ultimately been converted into electricity. If I'm mistaken, then I'm afraid that guy that had his brain cryogenically preserved so he could be reanimated some day is going to be out of luck, because that is how a cryogenic freezer works, from what I understand.
  23. Hi, I just happened upon this thread while doing some research for a "Stirling Turbine" of my own design. Doing research, because I haven't built it yet, and I was trying to figure out if it could really work or not. Maybe you folks would like to help me out. I was not at all aware of this "Kender" engine until just arriving here now, but it appears to be based on the same theory as my "Stirling Turbine" idea. Originally I was just trying to maximize the efficiency of a solar powered Stirling Engine I was working on. As I refined the design and had this machine running in my head... Well, I envisioned the sun going down... but it (The Stirling Turbine) just kept on running drawing indirect solar heat energy from the air. (Note, this was just ~in my mind~ and I don't know if it could actually work or not but I'm having a difficult time trying to figure out why it wouldn't) BTW.. in response to the "where is the heat sink ?" question... I would respond that the "heat sink" is the power turbine. The turbine works (in part) by converting heat in the air into kinetic energy, thus your "heat sink". That is, the heat in the air is not traveling to a conventional heat sink, rather, the heat is being CONVERTED into kinetic energy. This is how an "air cycle" refrigeration or "air cycle" air conditioning system works. Relatively warm or hot air goes into the turbine... The air molecules impact the turbine blades (Or disks - in a Tesla Turbine) giving up some of their energy. The only energy that a gas has to give up is in the form of heat, so the air temperature drops,... not only due to expansion but ALSO due to the heat energy being converted to kinetic energy. This is easy to see if you have ever used an air tool for any length of time. When an air tool is under a load, you will see frost forming around the air outlet as the air exiting the turbine is very very cold, not just due to expansion but also due to having given up some of its HEAT energy, even though the air entering the turbine may be quite warm - it exits ice cold (or colder). This type of refrigeration system is used on cryogenic freezers due to the extreem cold that can be produced using a turbine air cycle refrigeration system. Unlike the Kender engine there is nothing secret about my design... It has been posted on this Stirling Engine Forum where the theory is explained in detail: http://stirlingengineforum.com/viewtopic.php?f=1&t=461 And here are a few illustrations I made recently of different designs: http://prc_projects.tripod.com/stirling_air_turbine.html http://prc_projects.tripod.com/stirling_air_turbine_2.html In short, you are creating your "cold spot" for your temperature differential by converting the heat into kinetic energy through the turbine. This can be accomplished only if the turbine is actually doing some work. While under a load, such as turning a generator, the heat in the air or gas passing through the turbine is converted into kinetic energy then the kinetic energy is converted into electricity by the generator. In effect, this is your heat sink where the excess energy to maintain your temperature differential is being "dumped". But, in this case, instead of just being dumped as "waste" heat it is being CONVERTED into a usable form of energy. I would be happy to hear your comments and criticisms in regard to the theory and design of this "Stirling Turbine". BTW. I am using an open air cycle system rather than a closed system, though this could also be a closed system with the addition of another heat exchanger between the intake and the exhaust, but I thought, if you consider the atmosphere itself as part of the system... this becomes your "heat exchanger" - i.e. cold air is exhausted where it is re-heated by the sun and ambient air is drawn into the intake. So the air itself acts as both your heat/energy source and your "refrigerant". This should be relatively simple to build I think. Just to see if it works...
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