Kender Solar Engine

[npts2020]

TomBooth; I well understand how turbines and refrigerators (even gas ones) work. The problem I have with what you are describing is that once a gas passes through a turbine, it is in a lower state of energy, cooler and less pressure. The pressure part is what will keep this from working. After going through the turbine any other gases will want to flow to the exhaust side of the turbine until it builds up pressure that is higher than somewhere it is able to flow. While a check valve would keep exhaust from flowing backwards into the turbine, you are building up pressure there, which will cause the turbine to stop turning. It might be an interesting and informative exercise to build a prototype but I would not be investing my lifes savings in this venture.

[Tom Booth]

Exactly. The temperature difference is the power source here, and the displacer is just a necessary power loss in the process.

 

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.

 

Without a temperature difference it just won't run.

 

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.

 

What I was thinking was speeding up the expansion or evaporation of a fluid, which would cool it. A gas does work expanding regardless of whether that work is used for anything, and will cool regardless. A turbine drawing power to force the gas to expand will cool it on that side, but compress it on the other so that it can release its heat on the other side.

 

Ummm.... Yes, but that is not what is happening here.

 

A heat sink is needed even if you draw power from the gas.

 

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.

 

A liquefied gas can evaporate, or a gas expand. Either way it will cool. The only way to cool it is to raise its temperature it via compression (or use something colder than it), so that it can release its heat energy.

 

There is another way, which is what is primarily being utilized here, That is, making the gas to do work.

 

Honestly, I hadn't read it; I just had taken your word for it that its purpose was to cool the gas... now I see it is not.

 

That all depends on the application.

 

It's purpose is to recover power.

 

Again, that is only one application. In actual fact it both cools the gas and "recovers" or produces power at the same time.

 

 

The gas will cool just fine without the expansion half of the turboexpander.

 

Not sure what you are getting at there.

 

The wiki says it gives an additional 6-15% efficiency though.

 

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.

 

The reason I said that it did not follow that it supplies power from the fact that it is connected to the compressor is because depending on the relative sizes of the expansion and compression parts, it could instead be an additional draw of power.

 

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 ?

 

No problem. I also used to enjoy designing perpetual motion machines of various types, and always learned something when I eventually figured out why it wouldn't work. It was great fun.

 

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

TomBooth; I well understand how turbines and refrigerators (even gas ones) work. The problem I have with what you are describing is that once a gas passes through a turbine, it is in a lower state of energy, cooler and less pressure. The pressure part is what will keep this from working. After going through the turbine any other gases will want to flow to the exhaust side of the turbine until it builds up pressure that is higher than somewhere it is able to flow. While a check valve would keep exhaust from flowing backward into the turbine, you are building up pressure there, which will cause the turbine to stop turning.

 

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.

 

It might be an interesting and informative exercise to build a prototype but I would not be investing my lifes savings in this venture.

 

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:

 

While a check valve would keep exhaust from flowing backward into the turbine, you are building up pressure there, which will cause the turbine to stop turning.

 

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.

Edited February 2, 2010 by Tom Booth
added PS and a few additional notes

[Mr Skeptic]

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.

 

Yes, if you look at the efficiency of an ideal heat engine, you will see that it depends on a significant temperature differential to have any semblance of efficiency.

 

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.

 

A heat engine powered by a heat pump then?

 

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.

 

Wrong side. The gas is allowed to expand to lower its temperature, allowing the heat source (the refrigerator's inside) to transfer heat to the gas at a low temperature. The gas is then compressed to raise its temperature, so that the heat sink (refrigerator's outside) can dump the heat into the environment.

 

There is another way, which is what is primarily being utilized here, That is, making the gas to do work.

 

A gas cannot expand without doing work. It just can't. There is no way to do it. Whether that work is utilized is a different question.

 

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.

 

No, it may not. The laws of thermodynamics forbid it.

 

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 ?

 

The little birdy runs on water evaporation. If it runs out of water it will not work, and if you put it in a box it will not work. It does not run off ambient heat or it would work when you put it in a box.

 

You can run a heat engine on icecubes too, and it will even be more efficient than the birdy.

[Tom Booth]

A heat engine powered by a heat pump then?

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.

 

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.

 

Wrong side. The gas is allowed to expand to lower its temperature, allowing the heat source (the refrigerator's inside) to transfer heat to the gas at a low temperature. The gas is then compressed to raise its temperature, so that the heat sink (refrigerator's outside) can dump the heat into the environment.

 

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.

 

A gas cannot expand without doing work. It just can't. There is no way to do it. Whether that work is utilized is a different question.

 

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.

 

Rather, it may take less power to operate the displacer than what the turbine can produce.

 

No, it may not. The laws of thermodynamics forbid it.

 

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.

 

The little birdy runs on water evaporation

.

 

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.

 

If it runs out of water it will not work

 

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.

 

, and if you put it in a box it will not work. It does not run off ambient heat or it would work when you put it in a box.

 

You can run a heat engine on icecubes too, and it will even be more efficient than the birdy.

 

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.

[Mr Skeptic]

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.

 

http://en.wikipedia.org/wiki/Turboexpander#Refrigeration_system

 

If you look at the picture, you will notice that what comes out of the turboexpander is a liquid/gas mixture. Only a portion of the fluid is allowed to expand before that.

 

The majority of the cooling occurs past the the turbine, as the liquid evaporates. However the turbine is not responsible for the majority of the cooling.

 

I'm pretty sure that this gas does work on the compressor as it evaporates.

 

http://en.wikipedia.org/wiki/Vapor-compression_refrigeration

 

Here there is just a valve where the other had a turbine. The fluid still expands into a cold liquid/gas mixture, but here the expansion energy is not utilized. It is still 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.

 

Seems reasonable.

 

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.

 

But, you need a temperature differential to maintain the load on the turbine. The turbine does not absorb all the heat energy flowing through it, so it cannot by itself maintain a temperature differential. Eventually enough heat would be transferred past it to nullify the temperature differential if it were not maintained externally.

 

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.

 

Neither of these run on ambient heat, they both run on a temperature differential. The heat flow. The birdy acquires its temperature differential by evaporating water, and if the water does not evaporate will not function. You can't replace it with a heatsink (eg metal fins), but you can replace it with an ice cube. Put a heater on the other end, it will also work. It requires a temperature differential, nothing more, nothing less.

 

Put an icecube on the other end, or warm the beak, and it will run backwards if it can. This despite it still having "ambient heat".

[Tom Booth]

Neither of these run on ambient heat, they both run on a temperature differential. The heat flow. The birdy acquires its temperature differential by evaporating water,...

 

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 that this gas does work on the compressor as it evaporates.

 

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.

 

http://en.wikipedia.org/wiki/Vapor-c..._refrigeration

 

Here there is just a valve where the other had a turbine. The fluid still expands into a cold liquid/gas mixture, but here the expansion energy is not utilized. It is still cold.

 

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.

 

But, you need a temperature differential to maintain the load on the turbine.

 

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).

Edited February 4, 2010 by Tom Booth
fixed quotes

[Mr Skeptic]

"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..."

 

The second one is actually close to the truth. By wetting the beak, the air surrounding the beak has a higher vapor pressure of water than the surrounding air. This expands outward, doing work (and increasing entropy) to move the atmosphere. The molecules of water with the highest kinetic energy are the ones that evaporate (also doing work to free themselves from the surface tension of water); this results in a lower temperature.

 

So long as the humidity is taken away by the air and supplied at the beak, this will continue to work.

 

I will repeat however many times it takes, it does not run on ambient heat. If you can't tell, just put it in an airtight box so that the humidity of the air reaches 100%, then you will notice that it no longer runs despite both the water being there and the ambient heat being there. Ergo, it cannot be running on ambient heat or it would continue to function.

 

 

 

If such gases would liquefy just do to the expansion, what is the point of adding the turbine ?

 

It also recuperates some energy, and increases the efficiency.

 

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.

 

All gasses however will liquefy given enough pressure and a cool enough temperature.

 

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.

 

What if suddenly having an extra (and expensive) moving part becomes economically feasible due to the amount of refrigeration required?

 

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.

 

Then why is not all the gas allowed to expand, so that it can do more work?

 

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.

 

With all gas-based refrigeration thermal energy is transferred away from the fluid after compressing the gas, and to the fluid while expanding.

 

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.

 

The compressor uses energy to compress the gas, which heats it. The gas under pressure can be made to do work on the turbine, recuperating part of the energy used to compress it (and as it evaporates and expands it gets cold). Then it is evaporated to draw off heat, and back to the compressor.

 

Without the compressor, you get no temperature differential.

 

Without the turbine, you still get a temperature differential.

[Tom Booth]

I will repeat however many times it takes, it does not run on ambient heat. If you can't tell, just put it in an airtight box so that the humidity of the air reaches 100%, then you will notice that it no longer runs despite both the water being there and the ambient heat being there. Ergo, it cannot be running on ambient heat or it would continue to function.

 

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.

 

 

It also recuperates some energy, and increases the efficiency.

 

Right. "recuperates" some energy.

 

All gasses however will liquefy given enough pressure and a cool enough temperature.

 

Right, "cool enough".

 

What if suddenly having an extra (and expensive) moving part becomes economically feasible due to the amount of refrigeration required?

 

I don't understand what you are trying to say here. What's your point ?

 

Then why is not all the gas allowed to expand, so that it can do more work?

 

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.

 

With all gas-based refrigeration thermal energy is transferred away from the fluid after compressing the gas, and to the fluid while expanding.

 

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.

 

The compressor uses energy to compress the gas, which heats it. The gas under pressure can be made to do work on the turbine, recuperating part of the energy used to compress it (and as it evaporates and expands it gets cold). Then it is evaporated to draw off heat, and back to the compressor.

 

Right.

 

Without the compressor, you get no temperature differential.

 

OK

 

Without the turbine, you still get a temperature differential.

 

True, but not as much of a temperature differential as with the turbine.

 

The compressor uses energy to compress the gas

 

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 ?

[Mr Skeptic]

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.

 

Nope, the compressor is turned by a motor. The turbine cannot do it. Without the motor, it will not function, even if it starts off with a temperature differential.

[Tom Booth]

Originally Posted by Tom Booth

In this case, the energy being used by the compressor to compress the gas is coming from the temperature differential ...

 

Nope, the compressor is turned by a motor.

 

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 ?

 

The turbine cannot do it. Without the motor, it will not function, even if it starts off with a temperature differential.

 

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

[Mr Skeptic]

I couldn't understand your pictures. All I know is that it won't work, and involves temperature differentials and a turbine.

[Tom Booth]

I couldn't understand your pictures. All I know is that it won't work,

 

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.

[Mr Skeptic]

LOL...

 

OK, if you don't understand it, how do you know it won't work ?

 

It violates the laws of thermodynamics.

 

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 ?

 

From the lack of humidity in the air, and the humidity on the beak. This translates to a pressure differential, which can be used to do work.

 

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.

 

Except one works and one doesn't.

 

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.

 

The dippy bird increases entropy. Yours would decrease entropy if it worked, but it can't work because of that.

[Tom Booth]

The dippy bird increases entropy. Yours would decrease entropy if it worked, but it can't work because of that.

 

How, or in what way, or at what point do you see entropy decreasing in this system ?

[Mr Skeptic]

You are wanting to transfer heat from a colder to a warmer object, without expending energy to do so (and in fact wanting to gain energy).

[Tom Booth]

You are wanting to transfer heat from a colder to a warmer object, without expending energy to do so (and in fact wanting to gain energy).

 

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 ?

[Mr Skeptic]

If what goes in is warm air, and what comes out is cold air and energy, you must have made heat flow from the warm air into your machine. No matter how cold your machine started out, the flow of heat will eventually warm it up. Then it should cease to function, as otherwise you are transferring heat from the cold air leaving to the warm machine.

[Tom Booth]

If what goes in is warm air, and what comes out is cold air and energy, you must have made heat flow from the warm air into your machine. No matter how cold your machine started out, the flow of heat will eventually warm it up. Then it should cease to function, as otherwise you are transferring heat from the cold air leaving to the warm machine.

 

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.

[Sayonara]

I like the way that this thread filled up with shill accounts operated by Kender employees within weeks of the first negative replies appearing.

 

Good effort lads, but you'd be a lot more convincing if you (a) replied to ANY other threads, (b) didn't share IP addresses, © didn't use the same phrases, and (d) knew some physics.

[Mr Skeptic]

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.

 

What I said applies equally if it is open to the atmosphere. The room has nothing to do with what I said.

 

Also, if you want the closed box example, you can just have the energy your machine supposedly draws from the air remain in the room, eg lighting some light bulbs. It still will be a perpetual motion machine.

 

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.

 

Indeed, you have caught on. There is a temperature differential between the room and outer space, and the water transfers heat from the room to outer space. This is why putting it in a box will end its function.

 

Oh, and by a box I did not mean an insulated box.

 

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.

 

Nope, not if it is in an insulated room with the energy not leaving.

 

---

 

Anyways, the problem with your idea is that the turbine does not convert thermal energy into other forms of energy.

[Tom Booth]

I like the way that this thread filled up with shill accounts operated by Kender employees within weeks of the first negative replies appearing.

 

Good effort lads, but you'd be a lot more convincing if you (a) replied to ANY other threads, (b) didn't share IP addresses, © didn't use the same phrases, and (d) knew some physics.

 

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.

[Sayonara]

Not you personally. I've got my beady eye on one or two others though.

[Tom Booth]

Sayonara; Not you personally. I've got my beady eye on one or two others though.

 

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...

 

What I said applies equally if it is open to the atmosphere. The room has nothing to do with what I said.

 

Also, if you want the closed box example, you can just have the energy your machine supposedly draws from the air remain in the room, eg lighting some light bulbs. It still will be a perpetual motion machine.

 

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.

 

Indeed, you have caught on. There is a temperature differential between the room and outer space, and the water transfers heat from the room to outer space. This is why putting it in a box will end its function.

 

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.

 

Anyways, the problem with your idea is that the turbine does not convert thermal energy into other forms of energy.

 

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.

[Mr Skeptic]

At this point, only hard numbers can help you. Compare the work needed to compress the gas, and the work that your turbine can extract from it. Numerically.

[Tom Booth]

At this point, only hard numbers can help you. Compare the work needed to compress the gas, and the work that your turbine can extract from it. Numerically.

 

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.