Hi,

Several years ago I accidentally, while trying to devise a more efficient Stirling Engine (heat engine) stumbled upon a design that appeared, as far as I could figure - running the engine in my head - to maintain a "cold hole" or sink so as to create a temperature differential  between the sink and the solar heat trapped in the air, to run the engine.

The basic concept is to combine a Stirling type displacer / heat-pump unit with an air-cycle cooling system. The result is a relatively simple low-tech device with few moving parts that uses air as a medium throughout the entire system.

What I found particularly interesting is that Tesla described the theory behind just such an engine in some detail in one of his articles and for some time actually worked on building such an engine until his workshop burned down. He apparently never finished building his engine but it also seems he never abandoned the idea. In other words, he believed it to be a real possibility.

As far as I know, nobody knows exactly what Tesla's prototype, if he ever finished it, would have consisted of. So I cannot say that this is THE SAME engine, but the basic operating principle is identical to what Tesla described IN THEORY in his article, that is, an engine that takes in heat from the air to generate power by maintaining a "cold hole". i.e. it takes less energy to throw off the "waste" heat as some of the heat is being converted into another form of energy so that little heat ever actually reaches the sink. The energy thus converted, however great or little, is clear gain.

A Stirling Engine type displacer unit can be modified so as to work like a hydraulic air compressor. The compressed air can be channeled through an air-cycle heat pump which produces very high and very low temperatures. The heat-pump heat exchangers can then be channeled through the displacer chamber which would probably be best made of some kind of ceramic to ensure that the heat flows through the air inside the chamber rather than through the walls of a metal cylinder.

This should be relatively cheap and easy to build. The only way to find out if it will work. I cannot figure out any reason why it shouldn't work.

If anyone is interested I have posted more information / diagrams and animated images on other forums over the years as well as some videos of one of the components I managed to build: A very crude "tin-can" Stirling-Air-Pump,... but it worked!

This is more of a concept drawing rather than what the engine might actually look like:

And here is Tesla's article: The relevant chapters begin with the title: "A DEPARTURE FROM KNOWN METHODS—POSSIBILITY OF A "SELF-ACTING" ENGINE OR MACHINE, INANIMATE, YET CAPABLE, LIKE A LIVING BEING, OF DERIVING ENERGY FROM THE MEDIUM—THE IDEAL WAY OF OBTAINING MOTIVE POWER." about 2/3rds of the way down the page:

http://www.tfcbooks.com/tesla/1900-06-00.htm

Some exstracts from the article:

" This would be an inanimate engine which, to all evidence, would be cooling a portion of the medium below the temperature of the surrounding, and operating by the heat abstracted.

"...Conceive, for the sake of illustration, [a cylindrical] enclosure T, as illustrated in diagram b, such that energy could not be transferred across it except through a channel or path O, and that, by some means or other, in this enclosure a medium were maintained which would have little energy, and that on the outer side of the same there would be the ordinary ambient medium with much energy.  Under these assumptions the energy would flow through the path O, as indicated by the arrow, and might then be converted on its passage into some other form of energy.  The question was, Could such a condition be attained?  Could we produce artificially such a "sink" for the energy of the ambient medium to flow in?  Suppose that an extremely low temperature could be maintained by some process in a given space; the surrounding medium would then be compelled to give off heat, which could be converted into mechanical or other form of energy, and utilized.  By realizing such a plan, we should be enabled to get at any point of the globe a continuous supply of energy, day and night.  More than this, reasoning in the abstract, it would seem possible to cause a quick circulation of the medium, and thus draw the energy at a very rapid rate.

"Here, then, was an idea which, if realizable, afforded a happy solution of the problem of getting energy from the medium.  But was it realizable?  I convinced myself that it was so in a number of ways,... Heat, like water, can perform work in flowing down, ... But can we produce cold in a given portion of the space and cause the heat to flow in continually?  ...Heat, though following certain general laws of mechanics, like a fluid, is not such; it is energy which may be converted into other forms of energy as it passes from a high to a low level....  If the process of heat transformation were absolutely perfect, no heat at all would arrive at the low level, since all of it would be converted into other forms of energy.... We would thus produce, by expending initially a certain amount of work to create a sink for the heat  to flow in, a condition enabling us to get any amount of energy without further effort.  This would be an ideal way of obtaining motive power.  We do not know of any such absolutely perfect process of heat-conversion, and consequently some heat will generally reach the low level, ...But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium.  What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow.

"... I was just beginning work on the third element, which together with the first two would give a refrigerating machine of exceptional efficiency and simplicity, when a misfortune befell me in the burning of my laboratory, which crippled my labors and delayed me..."

So, when I first stumbled upon this, by running various alternative engine configurations in my head. Studying all I could learn about heat engines, the Stirling principle, air conditioning systems,heat exchangers, thermodynamics, etc. - probably 100 different "thought experiments", this engine kept running. That is, the visualization of it. It ran and kept running in my head for several weeks while I tried to find some conceptual flaw. Something I overlooked. Some reason why it shouldn't or couldn't work. At what point in the illustrated cycle would it break down. I could find no such flaw that would be fatal. A minor adjustment here or there might INCREASE EFFICIENCY, but that is all. Even a "Tin Can" model might work. A "Toy" model that could fit in your hand could work. Just like any engine THAT WORKS, it could be miniaturized. Or it could be made large. A relatively cheap model engine or prototype could be built to test the theory. See if it works.

So to "protect" the idea I began immediately disclosing the entire concept, drawing models and animations so it was "out there" and could not be "burried" somehow in some way.

I had contact with some potential investors, but in the end, investors are interested in something that is patentable, and due to releasing the details publicly and immediately there is no longer a possibility of obtaining a patent. It is "public domain". And we still do not know if it could work because a prototype has not been built yet.

So, due to the actions taken years ago (public disclosure) this is about as "open source" as you could get,I think.I hope this is OK. Reading through another thread I noticed this quoted:

"(04-27-2011 02:16 AM)admin Wrote:  And you are right, the main problem, I feel, with most everyones research is that they are not willing to share all the details. This makes any single person with all the details an easy target to remove from the equation"

These were my thoughts. i.e. there was certainly a real possibility that my own greed, if nothing else, might provoke me to refrain from disclosure in the hope of one day obtaining a patent or if obtained, or not, a patent might be "buried" somehow. Or perhaps "I" could be buried. So, if anyone is interested I AM willing to share all the details, if it is not already clear enough. If you (anyone) would like to help "tinker" with building a prototype, you may have resources I do not have. Feel Free.

I'm not looking for donations, but possibly some collaborative research would help move this along, if that is what the game is here.

At the heart of this thing is a modified Stirling type "displacer". Normally such a displacer in a Stirling Engine simply takes up or "displaces" space so that as it moves up and down the air in the chamber moves from the Hot to Cold end of the chamber and back over and over causing expansion and contraction of the air which usually powers a piston.

I thought that by adding check valves to capture the expanded air and keep it moving in one direction the piston could be replaced with a more efficient turbine. But could this work.

Here is a drawing of the "core" component:



And here is my effort at building a very crude and inefficient "tin can" (literally) test model:



Here is a video I made of this component deriving some power to "pump" some air into a balloon using a "cold hole" (ice) and ambient heat in the air to produce the temperature differential.

http://calypso53.com/stirling/Stirling_Ice_Pump_2.MPG (6.5 MB mpg)

It should be noted that although this looks like I am manually pumping air like a bicycle pump, this is not the case. The "displacer" inside the can is simply moving air from the top to the bottom of the can, There is virtually no resistance to this movement. In other words, I am not powering the "pump" or manually compressing air the air is compressing or pumping itself by its own expansion due to the resulting temperature change when the air moves from cold to hot. When moved in the opposite direction, hot to cold, the air in the can contracts and draws in additional ambient air to recharge the system.

It should also be noted that in a "real" engine - made to actually run on its own this cycling would be very rapid, like 10 cycles per second or whatever it is set to run at, like a regular Stirling engine. The previous animation posted earlier is, of course, in slow motion so as to get a view of the whole process in detail.

My little test model had "check valves" put together from old skate board ballbearing balanced on the end of some copper tubing. The metal of the can conducts heat. It should be of a non-heat conducting material. Probably ceramic. You want the heat to go through the air inside the can or canister not through the can itself. The air seal at the top was offering some resistance (friction) that potentially could be eliminated. The use of solenoids to "levitate" the displacer electromagnetically could eliminate friction and air leaks at the seal.

In other words, this very crude test model is as about as leaky and inefficient as you could possibly get. Wrong materials, worn out ball-bearings and cut off tubing for very leaky inefficient check valves, not a very great temperature differential, unwanted heat dissipation through the metal. Too little surface area for heat transfer, avoidable friction points, possible air leak points - lots of room for improvement. But as can be seen in the video - it does move air in the way intended - linearly to potentially power an air-cycle heat exchanger.

Compressed air gives up heat. Compressed air expanded through a turbine powers the turbine and gives up additional heat. The air, as a result, becoming extremely cold in the process of expansion and energy conversion as it passes through the turbine. The resulting cold air is then used to maintain the "cold hole" or "sink" which makes ambient heat available as an energy source.

Getting the thing started, somehow creating the initial "cold hole" or temperature differential to set things into motion is a question.

There would be various ways of accomplishing that. An electrical pre-heater, auxiliary compressor perhaps or simply putting a few chunks of dry ice down the exhaust shoot to cool down the pipes.

I have had some suggest that even if this worked to some degree you would need more energy to keep the displacer moving than you would ever get out of the turbine.

To me, this is equivalent to saying that a Stirling engine can't work. If the action of a displacer in a stirling engine can drive a piston why not a turbine? If Stirling engines work, why not apply the same principle but drive a turbine insted of a piston. The only difference is a Turbine is more efficient than a piston. You have reduced losses due to friction and changes in momentum which occur in a reciprocating engine.

There are a few elements in the previously posted animated drawing that might need some clarification. First of all, someone pointed out a long time ago that "insulation" is misspelled (o instead of u) sorry but I didn't feel like going through all those individual Gif frames to fix that.

The thing going up and down in the chamber, the "displacer" is also intended to serve as a heat "regenerator".

What this does is reclaim quite a bit of heat that would otherwise travel directly to the "sink". This would probably consist of a stainless steel mesh. This is a rather standard component in a regular Stirling Engine. The heat is repeatedly absorbed and then released by the regenerator/displacer. Some incoming Ambient heat may also be absorbed during "recharging", when Ambient air is flowing in.

The coils in the intake are intended, also to reclaim some heat not otherwise utilized for compression. This coil allows heat to re-enters the system while simultaneously pre-cooling the compressed air before it is released through the turbine.

This may be confusing or difficult to understand. The compressed air is pre-cooled so that when it is released through the turbine it will expand / some heat energy will be converted to electricity as it drives the turbine and the air will, as a result, drop in temperature well below ambient. It is the LATENT HEAT in the air BELOW AMBIENT that we want to extract and utilize to power the turbine. Not Hot compressed air but cool compressed air - so that the resultant VERY COLD air leaving the turbine can be utilized as our "on the fly" heat sink.

For this to work the compressed air needs to be pre-cooled back down to ambient so that when it expands through the turbine it both simultaneously releases LATENT INTERNAL HEAT ENERGY while becoming extremely cold. This is, I think, fairly standard and well known, or at least, commercially utilized expansion turbine operation.

The Sun has heated up Earth's atmosphere hundreds of degrees above the near absolute zero or interstellar space. It is that LATENT HEAT below ambient that we want to utilize which gives us a "cold hole" for the Ambient heat to flow into.

Compressed air, when released through a nozzle to drive a turbine escapes at great velocity. This high velocity air is what drives the turbine. In the process Latent Heat Energy is converted to power whatever load is put on the turbine. The Load is necessary. Without it the turbine would just free-wheel, the air would pass through and the Latent Heat would not be utilized.

So this is the reason for pre-cooling the compressed air. To get our very cold "cold hole" to create a sink for the ambient to flow into to power the "compressor" or Stirling type displacer-regenerator portion which draws in and compresses more WARM air.

Basically we have a "cold hole" protected by insulation from ambient heat. This Ambient heat is introduced into this controlled environment in metered doses and converted first into compressed air then into high velocity air then into electricity or whatever the turbine is driving. The additional coil in the "exhaust" pipe is to throw off any excess heat which is not converted.

Heat does not drive the turbine. It is the VELOCITY of the escaping COOL compressed air that drives the turbine. Heat only drives the compressor. Any excess heat should be thrown off before it reaches the turbine so that what drives the turbine is COOL compressed air that with expansion through the turbine becomes VERY COLD providing us with our "on-the-fly-" heat sink which maintains the temperature differential to keep the compressor running on the incoming and somewhat concentrated ambient heat.

 It may be, that the amount of energy that can be utilized from the latent heat in COOL compressed air is negligible. Enough to power a light or charge a battery perhaps, but if ANY energy can be utilized, that is FREE energy and running day and night continuously could be accumulated and could be enough to power an alternative energy system.

For example, charge the batteries in an electric car or batteries to run an inverter intermittently to power an alternative energy system.

On the other hand, the amount of energy put out could be considerable.

Here is a rather good description of a conventional LTD type Stirling Engine which describes the function of the displacer and "economizer" or regenerator. This is the basic Stirling Engine displacer chamber design I decided to start with being the simplest and one of the most efficient.

http://www.scimods.com/LTDStirlingEngines/aboutstirlingengines.html

Edit: That site is gone, but the page has been archived:

https://web.archive.org/web/20131126141857/http://www.scimods.com/LTDStirlingEngines/aboutstirlingengines.html

I am actually wondering; It has been said, or actually calculated that a Stirling Engine runs more efficiently on cold than it does on heat.

Probably everyone has seen a YouTube video of an LTD type Stirling engine running on ice or snow.

Well, if not, here's an example: https://www.youtube.com/watch?v=YCnTMNTL1yw

What I am wondering is, if the engine is converting a portion of the Ambient heat into mechanical energy so that the heat never actually reaches the ice (or snow), as Tesla surmised, (assuming I understand him correctly) then if the ice or snow were kept insulated, say in a thick Styrofoam pan so that the only way heat could reach it would be through the engine, the ice should melt or absorb heat from the engine at a slower rate than if it were exposed directly to the open air (or to an engine that was inoperative), since the engine is converting the heat to another form of energy before it gets to the "sink".

This should be a relatively easy experiment. Just need two Styrofoam pans full of ice, one with a Stirling engine running on top of it and one with an identical engine but not running. See which stays cold or frozen the longest.
 
Theoretically, the one with the engine running on top of it should stay cold or frozen longer since much of the heat trying to reach it is being converted into mechanical energy by the running heat engine before it gets to the ice.

If that does not happen then I would have to say that there is something wrong with Tesla's theory.

Anyone have a couple LTD engines they could try this with?

The more I think about this, the more I think that this "Ambient Heat Engine" could probably be built using "off the shelf" components. Here is how, and why.

I've worked in a lot of engine shops with air compressors. The compressor head on a regular shop air compressor gets hot enough to cook an egg despite having cooling fins and being exposed to the open air. All that heat is not coming from the compressor itself, from friction, but rather from the air that is being compressed and giving off heat (solar/ambient heat stored in the air).

After the compressed air sits in a tank and returns to room temperature, an ordinary air tool, like an air motor or impact wrench when running will emit bitter cold exhaust air. I know this because someone I worked with went to the hospital and had to go out on disability because he was taking some head bolts out of an engine with an air powered impact wrench and his finger got frozen solid and actually broke off because he had his finger over the exhaust port.

Ice formation on an air tool is a common and well known problem. They sell antifreeze for the purpose of preventing these tools from becoming clogged with ice at the exhaust port.

So here we have, in spite of precautions taken to prevent it, an enormously large temperature differential that has been created with nothing more than an ordinary shop compressor and shop air tool.

Now imagine we lubricate the compressor with something like PTFE (Teflon or "Slick 50") and INSULATE the compressor head and pipe. Take the pipe off of the tank and extend it. Wrap this extremely hot pipe around the hot side of a Stirling engine. Allow the pipe to continue from there through some cooling coils with fins exposed to the air to cool it back down to ambient, or even send it through a tub of water or radiator or both.

Now release the cool compressed air through an air motor coupled to an electric generator for power output. Now insulate the air motor and its cold air exhaust to prevent it warming up to ambient. Run that pipe back to the cold side of the Stirling Engine.

Now have the Stirling engine coupled to the compressor so that the Stirling engine can run the compressor.

First we can run the compressor with its electric motor until it gets hot. Then we turn on the air motor and let it run until it gets cold. We now have the temperature differential to run the Stirling Engine. Start up the Stirling Engine and shut off the electric motor.

Now the whole apparatus is running on heat extracted from the air. It is also delivering power via the air motor to the generator. At the same time it is continually drawing in more warm ambient air as "fuel".

This would not be "perpetual motion". It would be running on solar energy. The heat trapped in the air.

The only real problem I see with this is that a conventional compressor is not designed to operate at extremely hot temperatures. To operate for an extended period of time the compressor would probably have to be made out of some high tech ceramic or something, but an ordinary shop compressor should probably run long enough to prove the concept before it overheats. Another problem would be water vapor in the air condensing and freezing at the air motor and clogging up the lines. But again, it should probably run long enough to prove the concept before that happens. It could also probably be run in a closed loop using DRY air with the addition of a heat exchanger between the cold exhaust and the compressor intake.

Quote from Tom Booth on April 12th, 2012, 08:24 AM

The more I think about this, the more I think that this "Ambient Heat Engine" could probably be built using "off the shelf" components. Here is how, and why.

I've worked in a lot of engine shops with air compressors. The compressor head on a regular shop air compressor gets hot enough to cook an egg despite having cooling fins and being exposed to the open air. All that heat is not coming from the compressor itself, from friction, but rather from the air that is being compressed and giving off heat (solar/ambient heat stored in the air).

After the compressed air sits in a tank and returns to room temperature, an ordinary air tool, like an air motor or impact wrench when running will emit bitter cold exhaust air. I know this because someone I worked with went to the hospital and had to go out on disability because he was taking some head bolts out of an engine with an air powered impact wrench and his finger got frozen solid and actually broke off because he had his finger over the exhaust port.

Ice formation on an air tool is a common and well known problem. They sell antifreeze for the purpose of preventing these tools from becoming clogged with ice at the exhaust port.

So here we have, in spite of precautions taken to prevent it, an enormously large temperature differential that has been created with nothing more than an ordinary shop compressor and shop air tool.

Now imagine we lubricate the compressor with something like PTFE (Teflon or "Slick 50") and INSULATE the compressor head and pipe. Take the pipe off of the tank and extend it. Wrap this extremely hot pipe around the hot side of a Stirling engine. Allow the pipe to continue from there through some cooling coils with fins exposed to the air to cool it back down to ambient, or even send it through a tub of water or radiator or both.

Now release the cool compressed air through an air motor coupled to an electric generator for power output. Now insulate the air motor and its cold air exhaust to prevent it warming up to ambient. Run that pipe back to the cold side of the Stirling Engine.

Now have the Stirling engine coupled to the compressor so that the Stirling engine can run the compressor.

First we can run the compressor with its electric motor until it gets hot. Then we turn on the air motor and let it run until it gets cold. We now have the temperature differential to run the Stirling Engine. Start up the Stirling Engine and shut off the electric motor.

Now the whole apparatus is running on heat extracted from the air. It is also delivering power via the air motor to the generator. At the same time it is continually drawing in more warm ambient air as "fuel".

This would not be "perpetual motion". It would be running on solar energy. The heat trapped in the air.

The only real problem I see with this is that a conventional compressor is not designed to operate at extremely hot temperatures. To operate for an extended period of time the compressor would probably have to be made out of some high tech ceramic or something, but an ordinary shop compressor should probably run long enough to prove the concept before it overheats. Another problem would be water vapor in the air condensing and freezing at the air motor and clogging up the lines. But again, it should probably run long enough to prove the concept before that happens. It could also probably be run in a closed loop using DRY air with the addition of a heat exchanger between the cold exhaust and the compressor intake.

Tom you are absolutely right on using temperature differential to do work, and the way you explained it is correct. I use to work as an aircraft mechanic, working with jet engines. Jet aircraft manufactures tap hot compressed air off the compressor turbine part of the engine, run it through an orifice of sorts, which drops the temperature drastically to about freezing, then pipe this cold air into the cabin and seating area for the passengers, as air-conditioning, no Freon involved. I do think PTFE would be to soft, what I think would work would be siliconized aluminum. Good post Tom.:D

Siliconized Aluminum. Could be, though the idea of very high temperatures and aluminum... I've had to tear down a lot of lawnmower engines where the aluminum cylinders were scored badly from overheating. I was thinking more along the lines of a really old cast iron compressor. I've seen a cast iron engine lubricated with PTFE get glowing red hot and keep running beautifully, but whatever works.

One thing I think needs to be emphasized is that the expansion turbine or air-moter or whatever kind of air powered device is used for the power output would need to have a heavy load on it to achieve really cold temperatures.

The load is needed in order to convert the heat into work, thus forcing a drop in temperature. For example my co-worker who was removing long head bolts in an engine and got his finger frozen was using the air-wrench under a very heavy load unscrewing a lot of long bolts. It never would have gotten that cold under ordinary light use. Also an air-cycle cooling system that uses a turbine requires a load on the turbine. Without the load drawing off power you don't get the really cold temperatures.

So, in other words, for an "ambient heat engine" to work it has to be actively powering something external to it, like an electric generator with a load on it, like a heating element or something. The heat coming out of the remote load represents the heat being removed so as to achieve the cold "sink" that is creating the temperature differential to make ambient heat available for use.

I did some checking around and called a few places that deal in "high temperature air compressors" for "harsh environments" and so forth, but apparently, regardless of how much money you may have to spend, nobody is currently manufacturing any air compressors intended to run without some sort of cooling system, never mind insulated so as to retain the heat.

Quote from Tom Booth on April 13th, 2012, 06:13 AM

I did some checking around and called a few places that deal in "high temperature air compressors" for "harsh environments" and so forth, but apparently, regardless of how much money you may have to spend, nobody is currently manufacturing any air compressors intended to run without some sort of cooling system, never mind insulated so as to retain the heat.

Yes, it's going to be something you will have to invent, what temperatures are you talking about.

I've been looking into just what "siliconized aluminum" is, what it's used for etc:

"The typical reason people (and OEM’s) choose Al-Si (siliconized aluminum) bearings over conventional Cu-Sn-Pb (tri-metal) bearings is for seizure resistance and temperature resiliency (as well as cheaper cost)."

"Temperature resiliency" - sounds good.

That it is used for bearings in itself says something. "stronger and lighter than regular aluminum". I din't know this. Thanks!

"The ability of siliconized aluminum to pass off piston heat is far greater than a steel liner. With the ability to get more heat out of the motor faster, they were able to increase the power output without significantly decreasing piston life"

I'm still wondering though, it can conduct or throw off heat more quickly and so stay cooler, but can it actually withstand very high temperatures compared with other metals if the heat were intentionally concentrated and retained? I'm guessing, probably not but I don't really know. What is the actual melting point compared with other metals or alloys?

Quote from Tom Booth on April 13th, 2012, 06:48 AM

I've been looking into just what "siliconized aluminum" is, what it's used for etc:

"The typical reason people (and OEM’s) choose Al-Si (siliconized aluminum) bearings over conventional Cu-Sn-Pb (tri-metal) bearings is for seizure resistance and temperature resiliency (as well as cheaper cost)."

"Temperature resiliency" - sounds good.

That it is used for bearings in itself says something. "stronger and lighter than regular aluminum". I din't know this. Thanks!

"The ability of siliconized aluminum to pass off piston heat is far greater than a steel liner. With the ability to get more heat out of the motor faster, they were able to increase the power output without significantly decreasing piston life"

I'm still wondering though, it can conduct or throw off heat more quickly and so stay cooler, but can it actually withstand very high temperatures compared with other metals if the heat were intentionally concentrated and retained? I'm guessing, probably not but I don't really know. What is the actual melting point compared with other metals or alloys?

Well Tom I cast aluminum, see my YT video.:D

https://www.youtube.com/watch?v=S_18UHdlfM4&list=UU5MWkMsbXeqTSQGihR0is1Q&index=13&feature=plcp
Aluminum is in a totally molten state @ about 1400 degress F, I know the old time heat engines never went that high, but I don't know what temp they operated at, have never done any research on this subject.:D It would be of interest to find out.:D

Wow! Milling machine, Plasma cutter, welding equipment... you won't get any arguments from me.

If you can cast and mill aluminum  - well, lets make it aluminum.  If it runs and melts down from the heat -  congratulations! We just solved the worlds energy problems.

Quote from Jeff Nading on April 13th, 2012, 06:25 AM

Quote from Tom Booth on April 13th, 2012, 06:13 AM

I did some checking around and called a few places that deal in "high temperature air compressors" for "harsh environments" and so forth, but apparently, regardless of how much money you may have to spend, nobody is currently manufacturing any air compressors intended to run without some sort of cooling system, never mind insulated so as to retain the heat.

Yes, it's going to be something you will have to invent, what temperatures are you talking about.

Don't really know.

However hot a compressor would get running with the cooling fins ground off and the cylinder head completely insulated to retain heat.

Presumably this would void the warranty.

Quote from Jeff Nading on April 13th, 2012, 10:15 AM

...I know the old time heat engines never went that high, but I don't know what temp they operated at, have never done any research on this subject.:D It would be of interest to find out.:D

Some LTD Stirlings can run on as little as 1 degree temperature difference. The greater the difference between the hot and cold side though the more efficient. So extremely high or low temperatures are not absolutely necessary just better. You could run a Stirling cold with ice on one side and dry ice on the other.

But if we compress air for heat, we don't want to go to the trouble of compressing the ambient to concentrate the heat with a compressor designed with cooling fins to dissipate heat. That would defeat the purpose, but compressors aren't designed to do that.

I don't think that there are any real worries as far as overheating the compressor in a test. Just if it worked and a unit were built to run continuously the compressor would most likely need to be able to take alot more heat than normal.

All I know right now is that air compressors I've used tend to get really really really hot even with cooling fins and a fan. Not sure how long one would last without them. Especially insulated with the "Waste heat" recycled so that the air intake to the compressor may get  hotter and hotter and hotter the longer it runs.

But if it works, of course, then all that could be regulated with sensors and controls and baffles or whatever to keep temperatures, air flow etc. within some practical limits but at the sacrifice of efficiency.

I'm just anxious to get something put togehter to see if it works in the first place.

I mentioned ceramics because a major automaker built a prototype Stirling powered car years ago. (An old Popular Mechanics article I read. Don't remember which automaker, but they ended up using PTFE lined ceramic. The hotter it got the more efficient it ran. A ceramic Stirling engine could be up to 45% more efficient than any kind of metal engine just because it could get a whole lot hotter without melting down.

Jeff Nading,

I have a design for a modified LTD engine that acts as its own little pneumatic compressor. The main problem I've been having is finding a machine shop that could fabricate the parts.

What this would involve is taking a common LTD type Stirling. The kind you can see on YouTube running on the heat from someones hand or a cup of coffee or ice and replacing the top plate with one of a special design with a little compressor and hot air coils built right into the top plate. Instead of tubing to deliver the hot air through the displacer chamber the plate itself would have the channels cut right into it - like a maze.

I talked to a local machinist that makes precision parts, has computerized milling machines and such, but he didn't seem too confident about being able to make such a thing. It would probably have to be cast. I think aluminum would be just perfect as the heat would be generated by the compressor which would be built right into the top plate of the displacer chamber and dissipate quickly - directly into the displacer chamber.

Likewise, a bottom plate with a (Tesla) turbine built right into it could also be fabricated. This way the hot and cold are actually generated IN-PLACE and the heat exchanger "tubing" is actually just grooves in the plates themselves. (These plates would each probably have to be made in two pieces and sandwhiched together.)

If the concept works, this should run at a low temperature differential the same as any regulat LTD engine. In fact I think casting these special plates out of aluminum would be the best answer.

It could be started by setting it on some ice and running it until it begins to develop its own temperature differential from the heat of air compression on top and the cold of expansion through the turbine on bottom.

Since the compressor and turbine would be built right in and delivering the heat and cold right where needed there wouldn't be any need for so much external piping and insulation.

I have to leave for work, but I can provide more specific details and drawings later if you think you would be interested in actually casting the plates. Probably they could be 3D printed and then cast. I don't really know of any other way it could be done.

It could be a "kit" for modifying a regular model LTD engine to run on Ambient heat.

Quote from Tom Booth on April 14th, 2012, 07:19 AM

Jeff Nading,

I have a design for a modified LTD engine that acts as its own little pneumatic compressor. The main problem I've been having is finding a machine shop that could fabricate the parts.

What this would involve is taking a common LTD type Stirling. The kind you can see on YouTube running on the heat from someones hand or a cup of coffee or ice and replacing the top plate with one of a special design with a little compressor and hot air coils built right into the top plate. Instead of tubing to deliver the hot air through the displacer chamber the plate itself would have the channels cut right into it - like a maze.

I talked to a local machinist that makes precision parts, has computerized milling machines and such, but he didn't seem too confident about being able to make such a thing. It would probably have to be cast. I think aluminum would be just perfect as the heat would be generated by the compressor which would be built right into the top plate of the displacer chamber and dissipate quickly - directly into the displacer chamber.

Likewise, a bottom plate with a (Tesla) turbine built right into it could also be fabricated. This way the hot and cold are actually generated IN-PLACE and the heat exchanger "tubing" is actually just grooves in the plates themselves. (These plates would each probably have to be made in two pieces and sandwhiched together.)

If the concept works, this should run at a low temperature differential the same as any regulat LTD engine. In fact I think casting these special plates out of aluminum would be the best answer.

It could be started by setting it on some ice and running it until it begins to develop its own temperature differential from the heat of air compression on top and the cold of expansion through the turbine on bottom.

Since the compressor and turbine would be built right in and delivering the heat and cold right where needed there wouldn't be any need for so much external piping and insulation.

I have to leave for work, but I can provide more specific details and drawings later if you think you would be interested in actually casting the plates. Probably they could be 3D printed and then cast. I don't really know of any other way it could be done.

It could be a "kit" for modifying a regular model LTD engine to run on Ambient heat.

Hi Tom PM me and we'll see what we can do, Jeff.

The problem, or the reason rather, that I came up with the idea of cutting groves in a plate rather than using tubing is the difficulty of finding suitable tubing for what amounts to a "mini-refrigerator" or heat exchanger and the problem of having to bend it around into a coil with aharp bends to fit into the top of a displacer chamber without it kinking. Such a design would also eliminate the dead air spaces between and behind or around the tubes. Such dead air spaces will lower efficiency. Also any heat generated from friction in either the power piston (if used, I think a diaphragm might be preferable) and the compressor piston would also dissipate right into the top plate making that heat available almost immediately rather than having to somehow or other "reclaim" it and pipe it back in or something later.

In other words I think such a one piece (or two piece, fused or cemented together) top plate with everything built right into it would be IDEAL.

Hi, for some reason my PM thing doesn't seem to be working. I can't see if it was sent or not, though I used "save sent messages". Oh well.

Anyway, I was sending this sketch to give a general idea. Not very good at drawing freehand.

Is there some sort of CAD program that would be compatable with the 3D printer so I could make a proper 3D drawing maybe?



The squiggly line is intended to represent the channel cut or cast in the plate used instead of tubing for the HOT "condenser" pipe. There would be a similar plate for the bottom with the COLD expansion or "evaporator" pipe with larger groves.

The idea is to use pneumatics to increase the pressure. The power piston working a lever like a hydraulic jack to work the smaller air "pumps" or compressor cylinder(s). (1 or 2 could be tried) Not sure how well this would work or if it would be necessary. I'm still not sure how much pressure could be developed by the displacer chamber alone. I need to get some good check valves and run another test. The higher pressure might not be necessary so the displacer chamber could actually pump or compress the air through a check valve into the "condenser" plate directly (no power piston or lever or pumps).

I've also been looking at Tesla's "Fluid Diodes" that it might be possible to use in place of check valves (even fewer moving parts to wear out). This seems to be the sort of thing they were desgned for.

This is not exactly a Tesla "fluid diode" but rather one of my own design:



A blog about Tesla's Fluid diode or "Valvular Conduit": (A "check valve" with no moving parts)

 http://blog.makezine.com/2012/01/05/the-tesla-valve-one-way-flow-with-no-moving-parts/

I think my design might be an improvement - creating 3D toroidal (doughnut shaped) vortexes (plural of vortex ?) giving a straight run through the middle instead of Tesla's 2D back and forth loops. (What looks like ocean waves are actualy circular or funnel shaped not flat)

Actually a lot of Tesla's inventions were spin-offs from his work on the Ambient Engine, including the Tesla Turbine from what I understand. Tesla wrote that this "Valvular conduit" or fluid diode works best where there is a rapid back and forth change of pressure, which would be exactly the case in this application.

Edit: I imagine this might work (The "toroidal vortex fluid diode") as once the air got moving and the "smoke ring" type vortices were formed, getting air to flow backwards or the wrong way might be something like trying to go through revolving wringer washer rollers the wrong way.

I actually came up with this independent of Tesla. Before I ever heard of a Fluid Diode, but the original intent was to lower air resistance between moving air and any surface. I came up with the idea by studying how waves form by wind across water or sand. My reasoning being that Nature would follow "the path of least resistance". It seemed the vortexs between the waves was acting like air roller bearings reducing resistance. When I saw Tesla's "valvular conduit" I noted the similarity in design. Originally I imagined this being used to decrease drag by incorporating a wave shape into the surfaces of cars, trucks, airoplanes etc. It would be interesting to see if it works.

Quote from Tom Booth on April 14th, 2012, 06:30 PM

Hi, for some reason my PM thing doesn't seem to be working. I can't see if it was sent or not, though I used "save sent messages". Oh well.

Anyway, I was sending this sketch to give a general idea. Not very good at drawing freehand.

Is there some sort of CAD program that would be compatable with the 3D printer so I could make a proper 3D drawing maybe?



The squiggly line is intended to represent the channel cut or cast in the plate used instead of tubing for the HOT "condenser" pipe. There would be a similar plate for the bottom with the COLD expansion or "evaporator" pipe with larger groves.

The idea is to use pneumatics to increase the pressure. The power piston working a lever like a hydraulic jack to work the smaller air "pumps" or compressor cylinder(s). (1 or 2 could be tried) Not sure how well this would work or if it would be necessary. I'm still not sure how much pressure could be developed by the displacer chamber alone. I need to get some good check valves and run another test. The higher pressure might not be necessary so the displacer chamber could actually pump or compress the air through a check valve into the "condenser" plate directly (no power piston or lever or pumps).

I've also been looking at Tesla's "Fluid Diodes" that it might be possible to use in place of check valves (even fewer moving parts to wear out). This seems to be the sort of thing they were desgned for.

This is not exactly a Tesla "fluid diode" but rather one of my own design:



A blog about Tesla's Fluid diode or "Valvular Conduit": (A "check valve" with no moving parts)

 http://blog.makezine.com/2012/01/05/the-tesla-valve-one-way-flow-with-no-moving-parts/

I think my design might be an improvement - creating 3D toroidal (doughnut shaped) vortexes (plural of vortex ?) giving a straight run through the middle instead of Tesla's 2D back and forth loops. (What looks like ocean waves are actualy circular or funnel shaped not flat)

Actually a lot of Tesla's inventions were spin-offs from his work on the Ambient Engine, including the Tesla Turbine from what I understand. Tesla wrote that this "Valvular conduit" or fluid diode works best where there is a rapid back and forth change of pressure, which would be exactly the case in this application.

Edit: I imagine this might work (The "toroidal vortex fluid diode") as once the air got moving and the "smoke ring" type vortices were formed, getting air to flow backwards or the wrong way might be something like trying to go through revolving wringer washer rollers the wrong way.

I actually came up with this independent of Tesla. Before I ever heard of a Fluid Diode, but the original intent was to lower air resistance between moving air and any surface. I came up with the idea by studying how waves form by wind across water or sand. My reasoning being that Nature would follow "the path of least resistance". It seemed the vortexs between the waves was acting like air roller bearings reducing resistance. When I saw Tesla's "valvular conduit" I noted the similarity in design. Originally I imagined this being used to decrease drag by incorporating a wave shape into the surfaces of cars, trucks, airoplanes etc. It would be interesting to see if it works.

You can get 3D modeling programs like Blender or Google Sketchup for free.  I started by using Google Sketchup which is easy to learn, but has quirks in my opinion.  I kind of wish I started by learning Blender now, but I'm to far into Sketchup to turn back lol.  Maybe some day I'll give blender a go.  Would be nice to use it since it is open source.  

Nate

Quote from firepinto on April 15th, 2012, 09:34 AM

Quote from Tom Booth on April 14th, 2012, 06:30 PM

Hi, for some reason my PM thing doesn't seem to be working. I can't see if it was sent or not, though I used "save sent messages". Oh well.

Anyway, I was sending this sketch to give a general idea. Not very good at drawing freehand.

Is there some sort of CAD program that would be compatable with the 3D printer so I could make a proper 3D drawing maybe?



The squiggly line is intended to represent the channel cut or cast in the plate used instead of tubing for the HOT "condenser" pipe. There would be a similar plate for the bottom with the COLD expansion or "evaporator" pipe with larger groves.

The idea is to use pneumatics to increase the pressure. The power piston working a lever like a hydraulic jack to work the smaller air "pumps" or compressor cylinder(s). (1 or 2 could be tried) Not sure how well this would work or if it would be necessary. I'm still not sure how much pressure could be developed by the displacer chamber alone. I need to get some good check valves and run another test. The higher pressure might not be necessary so the displacer chamber could actually pump or compress the air through a check valve into the "condenser" plate directly (no power piston or lever or pumps).

I've also been looking at Tesla's "Fluid Diodes" that it might be possible to use in place of check valves (even fewer moving parts to wear out). This seems to be the sort of thing they were desgned for.

This is not exactly a Tesla "fluid diode" but rather one of my own design:



A blog about Tesla's Fluid diode or "Valvular Conduit": (A "check valve" with no moving parts)

 http://blog.makezine.com/2012/01/05/the-tesla-valve-one-way-flow-with-no-moving-parts/

I think my design might be an improvement - creating 3D toroidal (doughnut shaped) vortexes (plural of vortex ?) giving a straight run through the middle instead of Tesla's 2D back and forth loops. (What looks like ocean waves are actualy circular or funnel shaped not flat)

Actually a lot of Tesla's inventions were spin-offs from his work on the Ambient Engine, including the Tesla Turbine from what I understand. Tesla wrote that this "Valvular conduit" or fluid diode works best where there is a rapid back and forth change of pressure, which would be exactly the case in this application.

Edit: I imagine this might work (The "toroidal vortex fluid diode") as once the air got moving and the "smoke ring" type vortices were formed, getting air to flow backwards or the wrong way might be something like trying to go through revolving wringer washer rollers the wrong way.

I actually came up with this independent of Tesla. Before I ever heard of a Fluid Diode, but the original intent was to lower air resistance between moving air and any surface. I came up with the idea by studying how waves form by wind across water or sand. My reasoning being that Nature would follow "the path of least resistance". It seemed the vortexs between the waves was acting like air roller bearings reducing resistance. When I saw Tesla's "valvular conduit" I noted the similarity in design. Originally I imagined this being used to decrease drag by incorporating a wave shape into the surfaces of cars, trucks, airoplanes etc. It would be interesting to see if it works.

You can get 3D modeling programs like Blender or Google Sketchup for free.  I started by using Google Sketchup which is easy to learn, but has quirks in my opinion.  I kind of wish I started by learning Blender now, but I'm to far into Sketchup to turn back lol.  Maybe some day I'll give blender a go.  Would be nice to use it since it is open source.  

Nate

Got the PM 's Tom, thanks.

Last night my neighbor asked me to see if I could do something with his computer. I got it working. On the way out to go home he gave me an old IBM Thinkpad 770 laptop with a cracked monitor. Apparently it had been dropped and the screen was fractured.

Not knowing what else to do with it, I took out the hard drive this morning and dissassembled it with the idea of using it for a Tesla Turbine for this project. 4 GB IBM model DTCA-24090 E182115 HG. Rated 5V 500mA.

I never had one of these things apart before, but this looks good and solid. Nice metal platters (Some HD platters are plastic).

The drive motor is built right into or around the bearing in some way. I wondered if it were used as a Tesla turbine, could the motor be used as a generator ?

I found this video - so I guess the answer is yes:

https://www.youtube.com/watch?v=h48XYdJGfKs

Though I think the spacing between the platters will need to be reduced. It seems that less than 30 thousandth of an inch (0.016 - 0.030) is generally recomended depending on disk diameter, air velocity etc. Since this is a small laptop hard drive closer is no doubt better.

As is, the platters look to be spaced about 1/8 inch apart or about 6X more space than recomended.

Here is something else I found that looks like an interesting idea:

Towards the end of the page under "Optimizations:". Using an "Air Amplifier" nozzle.

http://www.stanford.edu/~hydrobay/lookat/tt.html

Would this boost power to the Tesla Turbine?

Unfortunately the writer's conclussion is: "efficiencies: YTBD..." That was in 2008.

Interesting idea though as these nozzles are supposed to increase air flow by up to 25 times over input. Some sort of vortex phenomenon.