# Electricity from ambient heat

Discussion in 'Physics & Math' started by Frencheneesz, Oct 3, 2008.

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1. ### Tom BoothRegistered Member

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61
I think this refrigeration system is particularly ingenious and interesting as it is very reliable, has no moving parts to wear out, there is virtually nothing that can go wrong with it, completely silent, no motor, compressor, pump.

Perhaps the confusion arises from the role of the hydrogen gas.

If you have what amounts to a continuous loop of pipe with a reservoir of ammonia and water at the bottom and if the boiler is releasing ammonia gas which is building up pressure on one side of the loop, then why doesn't the back-pressure push the water/ammonia solution backwards out of the boiler ?

Because the other side of the loop is filled with hydrogen gas to equalize the pressure.

Well then, if the pressure is equalized then what am I talking about as far as the ammonia boiling and building up pressure. It doesn't seem to make any sense right ?

Well, here is the ingenious part IMO.

As far as atmospheric pressure is concerned, if you put a pressure gauge anywhere on the system the pressure would read the same. There does not seem to be any pressure differential, so how can it possibly work ?

The answer is that the hydrogen molecules and the ammonia molecules are different in size. The hydrogen completely fills the space on one side to equalize the over-all pressure, but the ammonia molecules still have plenty of room to expand and move around between the hydrogen molecules as if nothing were there.

So if the pressure builds up throughout the system to 10 atmospheres and the hydrogen is at ten and the ammonia is at ten, when the ammonia is released into the hydrogen as far as the ammonia is concerned, there is no pressure there at all, it is free to move around BETWEEN the hydrogen molecules, like pouring sand from an hour-glass into a box tightly packed with bowling balls. The box is filled with bowling balls packed so tight that no more could fit, but as far as the sand is concerned the box is practically empty.

The hydrogen is an inert gas that does nothing but prevent back pressure and provide space between its molecules for the pressurized ammonia to expand and depressurize.

If you follow the actual refrigerant, the ammonia, the cycle is actually the same as any other refrigerating cycle. Basically: Compress a fluid, drive off the heat then decompress the fluid so it can re-absorb heat.

There are many different ways of accomplishing that, some simple, some very complicated but fundamentally all based on the same principle.

3. ### Tom BoothRegistered Member

Messages:
61
Returning to the above.

There are a few false assumptions here.

1) "In simple easy to follow logical steps the text there PROVES heat pumped out of the cold source is ALWAYS less than even the most perfect possible engine (a Carnot engine with zero friction) MUST deposit into the cold sink..."

Correct me if I'm wrong, but the assumption here seems to be that the reason this is a problem is due to the fact that since less heat reaches the sink than what you started out with, if you pump that heat out of the sink back to the hot reservoir the amount of available heat to run the engine would continually diminish until no heat was left to run the engine. All the heat would sooner or later be deposited in the sink so that in effect, the engine would run out of "fuel".

This is however, assuming a finite source of heat.

Ambient heat is not a finite source. You do not have to pump the heat out of the sink to replenish the heat source.

2) "... I.e. a closed cycle"

Who says that an Ambient Heat Engine has to operate on a closed cycle ?

The topic is "Electricity from ambient heat". The kind of cycle is not specified.

If we are limiting ourselves to a closed system with a finite source of heat than I would certainly have to agree. But we are not necessarily so limited are we ?

Utilizing Ambient heat in an open system we do not have to worry about returning the heat to a finite source. The heat source (Atmospheric Ambient Heat) is being continually renewed by the Sun all day long every day it cannot run out because we do not have enough heat at the sink left over to pump back into it.

5. ### Tom BoothRegistered Member

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61
I believe these statements are just plain wrong.

i.e. "Not true..." in reply to "In a Gas, the only kind of energy available is heat so in expanding and pushing the piston the gas/air gives up heat."

and "When the piston tops out, it does so because the air is hot and "full of energy", not depleted."

Sorry but this is wrong. I don't mean to be obstinate or whatever but it is just plain wrong.

"Heat" is a human interpretation. "Ouch ! That's Hot !"

What we are really talking about is kinetic energy.

"Pressure" represents latent "heat" i.e. kinetic energy.

If a gas does work it gives up kinetic energy. This translates into: If a gas does work it gives up heat.

If a gas does work to push a piston, turbine or whatever it gives up its kinetic/heat energy regardless of if that kinetic/heat energy is represented by pressure, velocity, or whatever.

To say "When the piston tops out, it does so because the air is hot and "full of energy", not depleted." is just plain ridiculous. Not true, False.

For the life of me, where do you come up with this stuff ?

7. ### Tom BoothRegistered Member

Messages:
61
I think we are thinking in different terms.

i.e. If a gas is gradually heated so that it gradually expands and pushes a piston out gradually, OK.

But in a real heat engine, "gradually" is not part of the equation, (usually), unless it is a very very sluggishly moving inefficient engine.

More realistically, the displacer moves rapidly from one end of the chamber to the other and the air in the chamber heats and pressurizes very very quickly and THEN when it has reached a high enough pressure and temperature it does work on the piston, pushes the piston out, gives up energy and cools.

If you get the gas to heat up very quickly and expand explosively then the gas has already reached its maximum temperature before doing the work and can only cool as it does work pushing the piston and transferring energy.

What you describe would only hold true where there is a slow incremental addition of heat along with a slow incremental expansion IMO, but that does not describe a real engine. Or we can settle on saying that it is somewhere in between depending on the efficiency of the actual engine.

At any rate, I think if the expanded pressurized air were held for later use and its temperature was stable by the time it was used as a power source (instead of immediately driving a piston) there would certainly be a sharp drop in temperature of the gas as it both expands and does work to power the load.

8. ### Aqueous Idflat Earth skepticValued Senior Member

Messages:
6,152
Tom,

The problem with your analysis of the ammonia absorption refrigerator is that is has no applicability to your device. You brought it up as a retort to my statement that you needed compression or suction to cool air directly. We can talk about the ammonia absorption cycle if you like, but it's a wild goose chase, since it will not lead to discovery of where your errors are.

Throughout your remarks you have been mixing the concepts of energy and work, among other things. You've managed to convince yourself that you have free energy from the ambient, merely by calling it heat. Of course, it's just ambient air, nothing more. It's only a heat source to a cold sink. But you don't have a cold sink. So you have to manufacture one. To do this requires energy. You seem to think you can make a temporary cold sink and then, using the potential difference between the ambient and this temporary manufactured cold sink, you can turn an engine which will continue to manufacture more cold air to keep the sink cold, to turn a turbine, and to produce cool waste air. You infer that this costs nothing once you get the device to cycle.

Your device is impossible for several reasons. First, it describes an over-unity device. There is a caveat here, because you are adding energy through the reciprocating solenoid motor, you just haven't specified how much. When we get to the bottom of that, you may be able to absolve yourself of the over-unity issue, but it won't matter. In order for the turbine to spin, you will have to supply more electricity to the motor than the turbine produces. A lot more. In this case you go from being over-unity to creating a device which does nothing but waste electricity. At this point your device is similar to connecting a motor to a generator, both at the shaft and at the power terminals, which is one of the more common errors among folks who believe over-unity devices are possible.

Your main obstacle to understanding why it's impossible is that you haven't put any numbers to the design concept. Without them, you are overlooking how large or small quantities are in relation to each other. This has led you into various false inferences, believing that your knowledge is sufficient to interpret how your device works. Thus, you look at it, and you see success.

I look at it and I recognize a device that has no placeholders for the numbers that I would begin estimating if you had showed me a plausible design. It runs on a cold air supply, which is ludicrous to begin with. Let me just address that point by itself quantitatively.

Let's start with the amount of energy that you're calling heat. For sake of argument, let's assume your ambient is at 25 °C and that you are furnishing a frigid supply at freezing, 0 °C, to initialize your device. First let's look at how much energy it takes to lower 1 L of air from ambient to freezing. For the moment let's ignore freezing condensate by imagining you are in a perfectly dry ambient.

Energy equals pressure times volume. Standard air pressure, 1 atm = 101.325 Pa. Multiply by 1 L and you get 101.325 J of energy. That's how much more energetic 1 L of ambient air is than 1 L of air at absolute zero.

Freezing cold air is 273 Kelvins above absolute zero. Your ambient is at 298 K. Energy is directly proportional to temp., so freezing air has 273/298 as many Joules per liter as ambient air, which is a factor of 0.9161. Multiply, and this tells you that you have about 92.8 J of energy in 1 L of freezing air. That is, freezing air has 92.8 J more energy than air at absolute zero.

Now solve for how much energy is available to a Stirling engine that's 100% efficient, from 1 L of freezing air: 101.325-92.8=8.5 J. This tells you right away that the most perfect device conceivable can develop at most 8.5 W of power as long as you continue furnish it with freezing air at the rate of 1 L/s.

You will immediately be confronted with an air conditioning problem concerning the rate of heat exchange. You might look at your sketch and ask yourself how you're going to accomplish that. When you go looking for actual A/C system specs you'll get a taste of how the Carnot cycle is the least of the constraints against a designer, and how expensive it will be to run this A/C unit.

Now let's start with 1 L of freezing air inside your device, ignoring the hurdle above. It's unclear how you plan to initialize your cycle, but presumably the air just gets very cold on one side of the displacer. Let's assume this has happened, that the air below the displacer has dropped very quickly and so far no mechanism has moved.

This 1 L of air was at 1 atm, but has now dropped to 273/298 = 0.9161 atm. It's unclear if that pulls the displacer down or sucks on the turbine or both. You would need to specify that and then we could develop this further.

I have no idea what you plan for your device at this initial condition. The amount of air that would bleed throughout the turbine, or, if a miracle occurred, actually caused it to spin, would be (1-0.9161) L = 84 mL. Remember, this is under perfectly ideal conditions, so that's an upper limit. At that point, your internal air reaches 1 atm and nothing else happens. I suppose you want to do something with the displacer to move the cold air around, but that's not clear either. At this point however, in the best of circumstances you can indirectly push the turbine the other way by using your displacer as a power piston (a point you've never made clear) in which case you dispel 1 L of freezing air through the turbine and push it back the other way.

At this point I can't proceed because it's not clear what your device does next. But so far all it's done is to consume a huge amount of electricity for a very negligible output. Assuming perfect conditions, you will generate only 8.4 watt seconds, which is about 0.15% the energy capacity of a NiCd AA battery, or about half that much compared to a typical AA alkaline battery. Which ever number you use, you would have to derate by about a factor of 10 to account for actual losses. Of course, I doubt seriously you can develop any electrical power at all with 84 mL of air at 0.92 atm.

So what's the next state of your device? Are you going to dump the cold air and reload it with ambient air which you continue to freeze with your external refrigeration unit? As you see, there's very little energy (8.5 J/L) to work with. And that's before losses.

9. ### Tom BoothRegistered Member

Messages:
61
Actually I brought it up as a retort to your repeated assertion: "Without a power cylinder, you have no way of converting energy. You have no way of compressing or expanding air. Thus you have no way of generating a cold side." and similar statements to the effect that it is impossible to generate cold without a "power cylinder", "power stroke" or "power piston". and that a gas cannot compress itself using a source of heat alone etc.

The ammonia refrigerator demonstrates that such a thing is certainly quite possible and this refrigerator is a demonstration of the fact.

In regards to the general topic of discussion: "Electricity from ambient heat", to do that, you need an imbalance. Some space relatively void of energy for the heat to flow into. As far as I'm concerned any means of accomplishing that is open for discussion. But feel free to move on, I think I've made my point that a "piston" or "power stroke" or "power cylinder" is not an essential feature of a refrigeration system. Heat can be used to cause a gas to compress itself directly without a "power stroke", piston, cylinder or any mechanical contrivance whatsoever.

Not entirely accurate but a relatively fair assessment. i.e. "turn an engine... ...to turn a turbine" is not quite accurate but aside from the details more or less an accurate portrayal of Tesla's proposal I think.

Personally, I believe the power requirements to actuate the displacer are negligible. This is true in a conventional Stirling Engine. Ultimately the displacer in a Stirling Engine is powered by heat, the same as the engine itself. If it makes things easier we can eliminate the energy requirements of the displacer. Lets say that the displacer is powered by a battery, the charge in the battery being maintained by a photovoltaic array. Not to say that you might not be right or that the power consumed by the displacer may not be significant but it would allow us to examine the rest of the proposed system in isolation.

Fair enough.

It does not "run on a cold air supply" IMO. That would be ludicrous if it were true.

Let's consider the ammonia refrigerator again for just a moment.

It utilizes a temperature differential. A heat source on one side, such as a gas flame and ambient as a sink. It uses this temperature differential to produce cold within a confined insulated space. Cold far below that of the available ambient "sink". We could periodically evacuate the cold from the cold space by opening the fridge. The device would remove the heat added.

It would be a mistake to assert that the ammonia refrigerator "runs on cold air". It is just as ludicrous to assert that the proposed "Ambient Heat Engine" runs on cold air. It is IMO, a straw man argument.

Any calculations based on such a false premise with no comprehension of the actual proposed mode of operation would be irrelevant at best.

It would have no effect on the displacer. It would not effect the turbine either and it would certainly not do both.

Correct me if I'm wrong but your calculations appear to be based on the false assumption that "freezing air" or the temperature of the "sink" somehow constitutes some kind of energy source for the proposed "Ambient Heat Engine".

I don't think that you have accurately described the "initial condition".

I have tried to explain the function of the displacer in a previous post > HERE I don't know how I could possibly make it any planer.

See the link above or again here > http://www.sciforums.com/showpost.php?p=2952617&postcount=159

For the last time, the displacer is NOT a "power piston" !!!!

Wow!

The engine is not going to "dispel 1 L of freezing air through the turbine" nor "push it back the other way". The whole premise on which you begin is false. You still, apparently, have no clue how a Stirling Engine converts heat into mechanical energy or what the function of a "displacer" is and some basic misconceptions regarding basic refrigeration principles.

Your only objective seems to be to muddle and confuse things in order to dismiss the whole idea without ever taking the time to understand anything whatsoever about it.

No I am not going to "dump the cold air and reload it with ambient air which you continue to freeze with your external refrigeration unit?"

Aside from your numerous misconceptions and misunderstandings so far, and your inaccurate assessment or description of the initial state of the system and so forth, No.

There is not, technically speaking, any "external refrigeration unit" if the system has already been initiated.

The cold air in the displacer chamber is not "dumped" at any point.

If you want to start at the point where the air in the displacer chamber cools and contracts, first of all you would need to know the starting temperature of the air prior to that, which is not ambient any more than the condenser coils on the back of your refrigerator dissipating heat are at ambient.

Nevertheless, to hopefully make things a little more understandable:

When the air in the chamber is cooled there is, of course, a reduction in pressure within the chamber.

It might be easier to conceive of a diaphragm pump attached to the side of the displacer chamber. In such a case when the pressure in the chamber drops the diaphragm would be drawn inward. This inward drawing of the diaphragm would draw Ambient air into the pump.

Next the displacer would shunt the cold air in the chamber to the hot end where the air would heat and expand, the result being that the diaphragm would be pushed out and the air in the pump previously drawn into the pump from Ambient would be pushed out of the pump and into the "condenser" coil or tube.

This might make things easier to think about or calculate on as no air or gas is moving in or out of the displacer chamber but instead the pressure changes in the displacer chamber are used to actuate a diaphragm pump or compressor attached to its side thus isolating the two functions making calculations easier.

It might help to think of this as an "air cycle system" bootstrapping its own compressor with the exception that the compressor runs on ambient heat or a temperature differential and so does not require the energy from the expansion turbine so the turbine could power something external to the system.

10. ### Aqueous Idflat Earth skepticValued Senior Member

Messages:
6,152
Ammonia can be exploited as a refrigerant in any of the ways I mentioned. You can compress it, suction it, or raise or lower its temperature. "A source of heat alone", the subject of this thread, is futile, because without heat flow there is no work and with no work, no refrigeration, and no engine cycle. The typical ammonia absorption system relies on fuel energy to heat the aqueous ammonia, to drive off the anhydrous gas, which is where the phase change comes in. On the flip side, it reverts to liquid automatically, due to the ammonia-water affinity, a chemical exploitation. But it's moot since you're not using ammonia in the water-affinity mode. So, as far as you're concerned, the need for compression (or vacuum) is a must. You can't get around it, since you're trying to chill ambient air. You will say no, then you will say yes when you describe how the air cools down. You're just confused and I'm trying to help you understand.
FYI, the mode of heat transmission in outer space is by radiation, which is a different topic altogether.
There is no reason to think that sinking energy into outer space has any practical application, or that wasting energy is the same as harnessing it, such as in a piston which converts volume changes into work.
More to the point, there has to be power spent. In your case, it's pneumatic power. That leaves you no alternative but to provide a power stroke. You haven't done so, and you're firm on that, which is a flaw, but you will also change horses and admit to creating suction as soon as you explain how you dropped the air temp later in the cycle.
Not any device, only one that constrains the volume. And this is of course moot since your trying to lower air temp, which invariably will require you to develop suction. Remember, volume change (at constant pressure) alters temperature. Somewhere in this arena is where the dogs got out.
I wouldn't hang my hat on what you think Tesla had to say until you can at least get past the technical hurdles you're facing. Until you grasp the volume issue, you're dead in the water.
It depends on whether you are using it to do compression, in which case we're back to calling it a power piston. And unless you do that, you have no engine. (So far.) Here, you only need to decide whether the displacer reacts to the 0.91 atm pressure in the chamber, which is 9% lower than the pressure above it, at the initial cool-down. Then, you need to apply the same analysis to the turbo. Then, you need to decide if either device bleeds air into the chamber, to equalize the pressure. Again: what's happening with volume? This is where the Carnot cycle diagram cures all ills.
If it were only a displacer we could ignore it. You haven't made that clear. It will all depend on how you answer the point I made immediately above.
It's ludicrous from an efficiency standpoint, nothing more, and only exists only because you proposed it. Your inability to realize that lowering the potential is no different from raising it, for purposes of conveying energy or harnessing it to do work, is your stumbling block. I thought you reconciled this in your mind a while back. As I said before, energy can be neither created nor destroyed. Any energy medium that contains a potential difference from ambient can be used against the ambient to do work, since that energy will move from high to low potential. This was the purpose of my initial post. As you can use compressed air to drive a ratchet, you can redesign the tool to run on suction. That's "running on suction". Following what you're proposing here, I can devise a way to ice down a Stirling engine, but just to develop vacuum in the power cylinder, then use that to drive my backwards ratchet. So then I'm "running on a cold air supply".

No, the only thing that we've discussed that runs on cold air is your device. There is actually a very old ammonia absorption device that shifts the average temp down a little by using a cool water bath as one temperature reference, and then heat from any source as the other. It was a household device to use in an ice box when ice was not available, in the early days of refrigeration.

As for modern ammonia refrigeration: first of all there are two common ways it's done. One is with a compressor. The one we are talking about here is the absorption cycle. It exploits the affinity anhydrous ammonia has for water. The ammonia gas will be sucked up into solution like a vacuum cleaner. This gives you a free change of phase from gas to liquid. On the opposite end of the cycle, you have to evaporate the ammonia from aqueous form to get it back into vapor. Normally this is done by heating. However, if for some reason the designed called for it, you could use suction instead to lower the boiling point to whatever temperature the design required.

Of course this has nothing to do with what you have proposed, which is why I noted that you need a power stroke. Again: check your volumes.
Let's clear up the premise. We've been talking about an engine that supposedly runs from ambient energy. It was already shown to be infeasible. You then proposed to do what I mentioned in my first post, which is to furnish a second potential, a cold source. All of that can be calculated, and it would behoove you to do so. Without at least some ballpark numbers, you're falling into the pit of over-optimism, which is a very bad place for a designer to be.
Based on what you are saying, I am left to assume that this chamber is not contained in its volume. Otherwise it would drop to 0.9181 atm and a slight vacuum would be available to do work. Again: what's happening with volume?

No, it's a truism. I thought you figured that out several pages back. Refer back to the discussion in blue above.
You left me no choice but to make assumptions. I'm assuming everything's at ambient, and then you kick on your refrigerator, and the air in the chamber drops to freezing. After that, it's up to you to say what happens next. What happens to the volume of cold air?
In a Stirling engine, that's true. You don't have a Stirling engine. As long as you continue to insist that there's no power stroke, you don't have an engine. The question is: what happens at the displacer, and/or turbine, when 0.9181 atm presents itself inside the chamber. Based on what you've said so far, I'm left to assume that it somehow bleeds out. But you would need to specify that. I'm just giving you the analysis to show you how to do it.

You're just in a quandary because you've never taken thermodynamics. I'm offering you free advice. Take it or leave it. But if you actually try to process what I'm telling you, you stand to benefit by learning. Don't sweat what seems like a tug of war. It goes on in the classroom, and it goes on in the real world. To have a viable design, you have to be able to articulate the fundamental principles of operation. I understand this is not where you are in your own personal development because you were honest to say so at the get go. So I'm giving it my best shot, thinking that at some point you're going to have a breakthrough. That's where the learning occurs. In the meantime you will tend to be suspicious because you're being given information that doesn't comport with your knowledge of the world. And that's just because you haven't taken thermo. What I'm telling you here is what any 2nd or 3rd year student in physics or engineering would tell you. You had several experts come in and tell you very concisely what principles are in play in your proposal. One was rpenner and another was Billy T. Other experts I've noticed, who you can learn from, include James R, Prometheus, AlphaNumeric, Origin, Trippy and a dozen others that I've encountered so far. These folks come from academia and industry with knowledge that mows you down. Since you expressed that you didn't understand the math, and you disputed the Carnot cycle, I reasoned that I could talk you into understanding those principles.
Most folks who studied science went through a similar rebellious period, or at least a period of astonishment and confusion, until the reasons behind the principles, and how the relate to one another, become clear. For some, it only comes through lots of long nights working actual problems. There's nothing like a good dose of reality, which comes from having to apply the principles, in order to break the mind out of its deadlock. Once you get there you can get past this concern. Ironically, you are resisting the laws of thermodynamics, mistakenly believing that these are artificial constraints of some kind. You simply haven't understood that they are reporting to you the laws of nature, from tons of people over centuries who did all the hard work for you. It's been chewed and spit out into a pap for you and me and the rest of the world to digest free of charge, since it would break our banks trying to recreate all the hard work that was done. But of course you can revisit any theorem and fiddle with it and you'll come up with the same results. Or, you get medal from discovering something someone overlooked. Here, you can rest assured that this idea you are toying with is so elementary it hasn't been overlooked. In fact, it's the type of problem mechanical engineers will see in their freshman class, probably on the first homework assignment. It's among the most fundamental type of issue scientists and engineers deal with every day.
Then there is no cycle after the initial startup with your external refrigerator.
In any case, it would help you to see your flaw by recognizing that you have no cycle. Again: what happens to volume?
I'm repeating back to you what will happen in the device (nothing) based on your diagram, and some of the explanations you've tried to give about how you think it works. I'm just reversing those into numbers to help you see how it's done.
This begs the question "what happens next" and how soon the external service can be shut down. If we get around to talking about latency, you'll see that you have to account for rates of heat exchange as well as the theoretical best case scenarios I formulated which was to help you get started with analysis. In any case, there is no cycle, so it's all moot.
This is why, in specifying or designing any device like this, you would want to show the states of the cycle, as the Carnot cycle diagram does. If you like, you can state back to me what happens at Phase 1 (where I tried to imagine your engine starting up), then, after some change occurs, call it Phase 2, describe what's going on, and so forth. In order to cycle, it must have states.
That's up to you to specify. I'm assuming the engine has been sitting out in the ambient for a week, and all internal temps and pressures are at ambient. If that's not your design idea, then maybe you can explain that.
Suppose there was a valve on the chamber wall where I could attach a suction hose. What will happen at the displacer and/or at the turbo if I went to 0.5 atm? Or 0.1? Until you make that clear, it's premature to say what will happen by cooling the chamber air. Volume is your stumbling block.
I can't get there from here. I'm stuck looking for and reaction at the displacer (does it move?) or the turbo (does it move?) in response to a 10% pressure drop from introducing freezing air. That's all a blur. The pressure drop you refer to will only last as long as the volume is constrained. This is where the Carnot cycle diagram comes in handy. I'm primarily looking for changes in volume as defining your state changes.
Do you understand that what you are describing is an over unity device which is impossible? And that, if over-unity were possible, we would all live like kings, never having to do any work, because we'd have an endless supply of free energy? This is a major stumbling block, one that we can get past as soon as you describe the states of your cycle in terms of volume changes.
So far you show it driving a turbo, but you've got the cold air going out with an explanation of what is powering that. There is no power input, so there can be no power output. Of course, you're relying on over-unity and just declaring it to have power. Unfortunately--for all of us who would live like kings--the universe trumps the best laid plans of mice and men. Energy flows across a gradient, from high potential to low potential, but it never creates itself (i.e. creates the difference) in the process.

No, what you are describing is a motor connected to a generator that keeps running after some small expenditure of energy to get it started. It's over-unity, so it's impossible. Since you obviously didn't understand that, I set out to get you started thinking in numbers, so you could discover for yourself that there's no source of cooling in your device without compression or suction (and this is where you diverged in the ammonia absorption cycle).

At this point, I'm still stuck wondering what you think happens next in your device--in the scenario I gave--where freezing air at 9% below standard air pressure (0.91 atm) starts the ball rolling. At 14.7 psi std air pressure, that presents 13.47 psi in the chamber, or a difference of 1.23 psi to work with. You say it contracts. What happens at the boundary where it contracts? Either something moves, reducing the volume, under the slight force presented by the 1.23 psi drop, or ambient air bleeds in to fill the void, or it remains constrained to 1 L volume because nothing moves and nothing bleeds, in which case no contraction takes places as you say. This is separate from the over-unity problem, but addressing one or the other of these will start to get you on the right track.

This is why you'll want to look into what's happening with your volume changes.

A Carnot diagram would have been so much simpler.

Last edited: Jul 2, 2012
11. ### Tom BoothRegistered Member

Messages:
61
Your jumping ahead to where the ammonia is reabsorbed by the water leaves out a very important part of the cycle.

You boil it to drive off the ammonia.

Now you suppose that the ammonia is reabsorbed by the water "automatically" with nothing in between ???

Somehow this addition of heat to boil the ammonia results in ice cubes in the ice box ????

How does hot steam and hot ammonia gas cool my food before being re-absorbed ???

Can you put some numbers on that ?

Hmmm....

Start out with ambient, add some heat, ice cubes... because????

Is it the evaporation due to heating that freezes the food or is it the "automatic" re-absorption of the hot gas into the water that freezes the food ??

I see you edited out the part where you can get boiling at any temperature you want by reducing the pressure. Did you recognize the fallacy of your own "over-unity device"???

I'm sorry, don't take it personally, but you have completely muddled the working principle of my proposed "engine" (OK, so it's not an engine exactly, call it what you will.) In the same way you have muddled basic refrigeration.

If you can't understand the basic refrigeration cycle then there isn't any chance of understanding my proposal as the refrigeration cycle is only one element, The Stirling displacer is another element I'm at a loss to explain any more clearly, How cooling is effected by turbo-expansion, well,... The Air-cycle-system... I don't have much hope of making those clear either and putting it all together ?

I'm afraid it just isn't gonna happen.

And we haven't even touched upon boundary layer effects in the tubing, the regenerator in the displacer, etc. etc.

I can't even seem to get across that the displacer is not a piston.

Maybe if you heard it from someone else:

Need more ?

Yet you continue to say things like: "It depends on whether you are using it to do compression, in which case we're back to calling it a power piston...."

Over and over again.

Use some of those links to read up on what a displacer is, what it does, how it works, etc. then maybe we can get somewhere.

12. ### Tom BoothRegistered Member

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Ummm... Sorry but, I did not say "outer space". I had made some reference to outer space earlier as the eventual or ultimate heat sink but that is not what I mean here by "Some space relatively void of energy for the heat to flow into."

Refer back to Tesla's article for the context. What he described as a "cold hole". Put more simply or directly, any heat sink artificially generated for the sake of establishing a temperature differential to run a heat engine on ambient heat.

13. ### Tom BoothRegistered Member

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I don't know what you mean by "not any device". You seem to be misreading what I wrote. What I wrote should be read "Heat can be used to cause a gas to compress itself directly without (cut: a "power stroke", piston, cylinder or) any mechanical contrivance whatsoever."

That is, you don't need any "mechanical contrivance" to compress air, not any device will do the job.

A refrigeration system "constrains the volume" of the refrigerating fluid being compressed with a throttle, valve, turbine, choke point in the tube or some such thing to restrict the flow of fluid through the system.

Before the choke point the fluid is pressurized or compressed. Not 100%. some of the fluid gets through the choke point but it is still pressurized within a confined space or tube.

Temperature is lowered by driving off heat while the fluid is still pressurized. The energy to pressurize the fluid is driven off, and then some. When the fluid passes the choke point into a larger space it is "hungry" to get back the energy it lost while pressurized.

If you want to you can say that in an "open" Air-Cycle-System that atmosphere "sucks" the pressurized air through the choke point if you want to, if you just have to have "suction" in the loop somewhere.

You can say that atmosphere "sucks" the air out of a tank of compressed air, if it is easier for you to conceptualize it that way. But,... personally, I think that for most people it is easier and plainer to say that the compression pushes the gas through the choke point rather than that the relative absence of pressure "sucks" the fluid or gas out of the pressurized system.

If you must,... Atmosphere (1 bar) relatively low pressure "sucks" the air from the nozzle in the turbine, but that is IMO a rather convoluted way of looking at things.

You do not have to "suck" the air through the choke point to cool it. In refrigeration you pressurize the gas, air, or whatever is being used as a refrigerant, at which point while still under pressure you can drive off heat.

Then when it is released from pressure it expands and cools. There is no necessity for any "sucking", just a release from pressure or compression.

14. ### Tom BoothRegistered Member

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If you have a sealed canister with a small piece of balsa-wood inside, increasing or decreasing the pressure by heating or cooling the canister has no appreciable effect on the balsa-wood. So long as the balsa-wood, or whatever material its made of displacer has room for air to pass around it or through it, temperature and pressure changes will have no effect on it or influence it in any way. Heat one end and cool the other, shake the can so the balsa-wood rattles around, the balsa-wood doesn't do anything but take up some space inside the canister. Its movement inside the can may cause the air to heat and pressurize or cool and depressurize depending on which direction it goes if the temperature of the ends of the can is unequal but temperature and pressure changes have no effect on the displacer.

Whatever happens the pressure on the displacer is equal on all sides. It is not pushed or pulled or otherwise effected. If the pressure changes in the can it rattles around inside just as easy. Pressure changes do not restrict the movement of the displacer in any way.

I have, I think, made that abundantly clear. It is a displacer. Always was, always will be. Nothing is ever going to change it into a "power piston". You keep insisting it has to be a power piston. It has to drive a crankshaft or something. No. All it does is "displace". It shifts air from one end of a chamber to another. The pressure changes are equal inside the chamber, above, below and all around the displacer. If the pressure goes up, it goes up on all sides, top, bottom, middle, above the displacer and below it and around it.

Since the displacer is rattling around loose in the chamber, pressure changes have no effect on the displacer. The pressure can change however it will, this does not push or pull the displacer or make it more difficult to move. There is nothing to restrict the movement of the displacer whether the pressure goes up or down.

There is no such thing as "the 0.91 atm pressure in the chamber, which is 9% lower than the pressure above it"

The displacer cannot react to something that does not exist!!!!

The pressure above the displacer is the same as the pressure below it. If the pressure changes it changes on all sides of the displacer.

Do you understand that the pressure of a gas is equal everywhere within a container ? Basic stuff.

You keep insisting I need to listen and be enlightened by your wise words or something but if you had any clue what you were talking about you would not be asking me uninformed questions and insisting that I must solve nonexistent problems.

15. ### Tom BoothRegistered Member

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First of all, let me explain why I even bother.

I think that this subject of "Electricity from Ambient Heat" is rather important. I think Tesla was on to something. I think everybody agrees that if "Electricity from Ambient Heat" could actually be realized it would revolutionize everything. No ?

So when some self proclaimed expert comes along pretending to know what he or she is talking about and proceeds to dismiss the idea on bogus grounds for whatever reason I feel it is of some importance to set the record straight for anyone who might actually be interested in the subject and who might be mislead into believing it has no merit based on some nonsense presented by a supposed know it all.

Anyway, just to set the record straight:

This is all nonsense. Nothing personal, but it appears you simply just don't have any idea what you're talking about.

The fact that ammonia combines easily or is absorbed easily by water or that the application of heat can drive the ammonia out of the water really has nothing whatsoever to do with the "phase change" in refrigeration. Not in refrigeration in general, not in the ammonia system.

You describe the absorption and release of the ammonia from water, which is really just a convenient way of "storing" the ammonia in water and mistake this for the "phase change" in the ammonia system which has nothing to do with ammonia's affinity for water.

Salt reacts with water also. Leave salt out on a humid day and it absorbs water from the air. If you combine water and salt you get "salt water" not a "phase change".

Salt is soluble in water. Ammonia is VERY extremely soluble in water.

Ammonia combined with water forms "ammonium hydroxide". Basically hydrated ammonia or ammonia and water.

"Anhydrous ammonia is just ammonia. "Anhydrous" simply means "without water" in Greek. So anhydrous ammonia is just plain ammonia without any water. A distinction is made because ammonia and water are so often found in combination that there has to be a special name for it as the common name "ammonia" is mostly water.

What does any of this have to do with "phase change" in refrigeration. NOTHING.

Do you know at what temperature pure ammonia liquifies at 1 atmosphere ?

Liquifying ammonia is not the same thing as ammonia being absorbed and chemically combined with water.

To actually liquify ammonia at any temperature above minus 27 degrees (-27.4 degree Fahrenheit to be exact) you need pressure.

Ammonia liquefies rather easily under pressure. Otherwise you have to cool it down below its boiling point (-28° F or -33.4°C)

You can't get any "phase change" out of ammonia by heating it with a gas flame or even by heating ammonia and water to boiling.

Water absorbing ammonia is not "phase change".

Your description doesn't even include the actual refrigeration cycle of the system. You have mistaken solubility for "phase change".

So how do you expect me to take anything you say seriously ?

16. ### Tom BoothRegistered Member

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True.

Maybe half right. The "pneumatic power" or simply pressure is developed due to the temperature differential, just like the ammonia refrigerator. Apply heat and you get expansion and pressure.

No alternative ? Power Stroke ?

Apply heat and the internal pressure increases. Did you ever can corn in a pressure cooker ? Well, I guess not. If you did you would be afraid to eat it because how could a pressure cooker possibly work and develop pressure without a power stroke ? Obviously that's impossible. Until the government mandates that all pressure cooker must have a piston and a power stroke I won't eat anything out of a can ever again.

Once again, the displacer is not a piston. It doesn't have a "power stroke". It doesn't need a power stroke. It creates pressure simply by moving a quantity of air into contact with a hot surface. Not unlike presenting heat to ammonia to expand it and create the necessary pressure so it can be liquified at room temperature.

Sorry but I did not and do not propose any such thing. Someone else insisted that evaporative cooling was the "power source" or some such thing in the drinking bird. I contested that. IMO the bird runs on Ambient Heat. My proposed device also runs on ambient heat. I never proposed that anything could run on a "cold air supply".

Aside from the fact that your proposal is ummm... not really possible, but just supposing that you could really "devise a way to ice down a Stirling engine, but just to develop vacuum in the power cylinder, then use that to drive my backwards ratchet." Sorry, but no. You are not "running on a cold air supply". Lets get this clear now. You are the one proposing this idea of running anything on a cold air supply. IMO its pure nonsense.

OK, so we have your supposed ice/Stirling powered redesigned ratchet "running on suction".

What is the reality ? You take away air to create a vacuum. Can your tool run on a vacuum ? No.

What it is running on(sic) is the higher potential atmospheric pressure. You suck and it blows. < < can I say that ?

Oh, never mind, you didn't edit out that bit of silliness, sorry.

So you have "free change of phase" as well as boiling ammonia at "whatever temperature."

So I could boil out the ammonia with "suction" and get the water to reabsorb the ammonia all for free at room temperature or whatever temperature we want.

Thank God!

Well, you finally got something right. We are supposed to be talking about an engine that runs on ambient heat.

Some have asserted this to be "infeasible" though not very convincingly IMO.

No, I did not propose to do what you mentioned in your first post. I distinctly recall ignoring your first post as you were talking about subjects unrelated to this thread. Geothermal energy and the like. If you think that I "proposed to furnish a second potential, a cold source" you are dreaming. If you think I based my non existent proposal on your suggestion you are doubly dreaming a dream within a dream.

Huh ?

Is it possible for a container to be contained in its own volume ?

Please, if you are going to continue posting at me at least make some kind of sense.

Thanks anyway, but I've already been there and would rather not.

I doubt it.

I agree. It was not overlooked by Tesla. Unfortunately, it seems, his workshop was burned to the ground before he finished his work. Or maybe he had a pet theory that really was not possible or practical and just refused to let go of it and made up excuses for his failure. Personally, I think Tesla was probably right. His ideas about an Ambient Heat Engine make a lot of sense. You on the other hand, sorry to say, make no sense.

Right. when you get unstuck let me know. The displacer does not have any "reaction".

I'm sure. wish I could help, but...

Sure, the turbine moves, along in the course of things, but not from any "10% pressure drop" and not from "introducing freezing air". At best you have it backwards on both counts.

No.

Ummm... personally I don't mind work, but OK. sure.

Ummm... you seem to be stuck on a lot of things. Volume changes being one of them.

I've already pointed out that refrigeration can be effected by an application of heat to a system without any volume change. No power piston. Nothing mechanical.

I have an ammonia absorption refrigerator in my house. I'm quite sure that I've witnessed it working just fine on a gas flame and it does not changed in volume in any way.

You insist that my design cannot work without this that and the other thing. My efforts to demonstrate that these things are not necessary by providing working examples in everyday use falls on deaf ears.

Volume changes. Any volume changes ?

Displacer chamber, pipes, turbine, more pipes... Hmmm.... Not a volume change in there anywhere. sorry.

As I said you can add a diaphragm if you like. then you can see some volume change but that would be an unnecessary modification to provide your mind with something to work on.

17. ### Tom BoothRegistered Member

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Sorry, I was mistaken.

When you compress air into the system, presumably earths atmosphere would shrink in volume by some very very very very small fraction.

18. ### Tom BoothRegistered Member

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Maybe I can make things a little more clear.

Start with a sealed canister. Or, almost sealed. That is, it could have one way check valves or it could have a diaphragm or possibly some kind of pneumatic valve or even a piston.

Whatever the case, It is pretty much sealed. Unless there is some internal or external pressure change.

If there is a pressure change, either a check valve opens, or a diaphragm or piston (not the displacer) in a pneumatic valve moves to allow the pressure to equalize with whatever is on the other side of the valve. Atmosphere or another chamber or whatever.

To begin with, we artificially heat one side of this can and cool the other. This does not necessarily change the pressure. It is not intended to change the pressure.

You could say that by heating one side and cooling the other the pressure remains the same in the can as the potential pressure change due to the temperature differential remains in balance. The potential expansion or pressure increase from the hot side cancels or balances out the contraction or pressure decrease from the cold side.

The role of the displacer is to turn this potential pressure change into actual pressure change by blocking contact with the heat source or the cold sink.

Move the displacer to the cold side and the air in the can is on the hot side. The potential expansion becomes actual. Move the displacer to the hot side and the air is no blocked or insulated from the heat source. Instead the air in the chamber is exposed to the sink. The pressure is lost, heat goes to the sink and the air contracts. Pressure decreases.

So what happens in response to the pressure changes ?

A check valve opens or a diaphragm moves or a piston moves or a pneumatic valve opens. Pressure on both sides of whatever between the inside of the can and the "outside" equalizes.

If the valve opens at high pressure, the pressure equalizes at relative high pressure. If the valve, (or a different second valve) opens at low pressure, the air in the canister and on the other side of the valve equalize at low pressure.

The displacer keeps the pressure alternating between high and low by moving back and forth from hot to cold and back again.

Check valves allow pressure equalization in only one direction.

So if you put two check valves on the can, when the pressure increases, the high pressure check valve will open and there will be equalization of pressure at high pressure.

When the pressure in the can decreases, the low pressure check valve will open and there will be pressure equalization at relatively low pressure.

The high and low pressure valves are identical. What function they serve depends on their placement and orientation.

The high pressure valve lets pressure equalize at high pressure. The low pressure valve lets the pressure equalize at low pressure.

At high pressure, what is on the other side of the check valve is a tube. The tube retains the high pressure because it is practically closed off at the other end.

At low pressure, what is on the other side of this second check valve is atmosphere.

At high pressure in the can, the high pressure check valve opens to keep the air in the tube at relatively high pressure.

At low pressure, the air in the can equalizes with atmosphere.

You can accomplish the same thing with a diaphragm. On the other side of which is a pneumatic air pump or compressor (The "pump" consists of the same two check valves as before but placed in a separate compartment)

That is, at high pressure in the can, the diaphragm (if used) pushes out or expands into the second chamber. Air is forced out of the second chamber at relatively high pressure into the tube.

At low pressure the diaphragm moves into the first chamber creating a partial vacuum in the second chamber and air in the second chamber equalizes with atmosphere at relatively low pressure.

(IMO though, the diaphragm would be redundant. The displacer chamber itself may serve as the external pump, thus reducing the number of moving parts. This however remains to be seen. There may be some advantage in keeping the functions and therefore the air masses separate. (for-instance, a completely sealed displacer chamber could be charged with a special gas with a higher expansion rate than air if such a gas exists, I have not researched this. Also, in passing through the displacer there may be some undesirable mixing of ambient heat with cold air. This would need additional research or testing).

The effect is that due to the pressure changes and the one way valves, the high pressure of expansion at high heat is temporarily stored in the tube.

At low pressure the air in the can equalizes with atmosphere.

The result of this heating and cooling is that the high pressure hot air is moved or pumped into the tube and more atmospheric air (containing additional ambient heat) is drawn in to replace it.

In other words, the can with the displacer inside, heated at one end and cooled at the other acts as a pump or compressor who's energy source is the temperature differential.

We know that compressed air heats up.

We have ambient air coming into the system at low pressure and entering the tube at high pressure. The high pressure air in the tube should therefore be at a temperature greater than ambient.

This heat should, theoretically, help to maintain the temperature of the "hot side", or the initial condition created when the can was heated "artificially" some degree above ambient as heat is continually being added from ambient, its temperature increasing somewhat due to being compressed into the tube.

The temperature and pressure in the tube should now both be some degree above ambient temperature and pressure. The tube is narrow (as in refrigeration systems), as in passing through a narrow tube more heat is generated. (Possibly due to an increase in the number of collisions of the air molecules in a confined space. "resistance" due to boundary layer effects. In refrigeration systems, the inside walls of the tubes are fluted (intentionally roughened or grooved) Presumably to increase turbulence.)

Therefore at the other end of the tube there is a pressure differential between the air in the tube and atmosphere.

The pressure is relieved through a turbine, a pneumatic motor, or a compressed air motor or whatever back to atmosphere.

As the air expands through the turbine it's temperature drops.

This temperature drop could, theoretically be used to maintain the initial cold at the cold end of the displacer chamber.

Initially the displacer chamber was artificially heated and cooled. Once started the heat of compression and the cold of expansion is supposed to maintain the initial condition.

IMO, this could only be possible if energy is extracted at the turbine lowering the temperature of the air below that necessary to start up the system. A heat exchanger can also remove some heat from the tube by simply exposing it to ambient. (As is accomplished in refrigeration systems)

That is, heat would have to be converted by the turbine, leaving the system as electricity, or removed with a heat exchanger (or both) before expansion is allowed to occur.

There is no need to return the heat to the heat source with a heat pump. The source of heat is ambient and remains virtually unchanged due to the energy extracted from it.

The EXERGY in ambient is inexhaustible.

The energy leaving the system as electricity (and or heat exchanger) prevents the system from reaching equilibrium. Like the energy leaving the drinking bird due to evaporative cooling prevents the system from reaching equilibrium.

A regenerator can be added to the displacer to minimize heat loss to the sink.

Theoretically, if the air temperature from the turbine is colder than necessary, the freely available ambient heat could be added back to the air at the moment it is released into the turbine.

The regenerator/displacer could have a heat reflective upper surface so that the heat generated to expand the air in the chamber is reflected back after use.

Heat or hot air naturally rises. For this reason the hot tubes are at the top of the chamber. Heat given off by the tubes to expand the air in the chamber would tend to be reabsorbed by the cooled tubes. This should, theoretically, improve efficiency over the typical Stirling engine where heat is typically applied at the bottom of the chamber.

I believe this was part of the rationale for concluding that a Stirling Engine runs more efficiently "on ice". As the heat source (Ambient) is at the top and there is a natural tendency for the waste heat to be reclaimed, simply because hot air in the chamber rises so the temperature differential is easier to maintain.

As air is used to compress air, the heat losses normally found when air is compressed should be minimal. The heat energy is transmitted from the air doing the compressing to the air compressed rather than being lost to piston, cylinder, cooling fins (to prevent the piston overheating) etc.

The ambient heat is retained, the energy of compression is retained. Heat exchangers and a regenerator can be used to reclaim potential "waste heat".

Cold becomes the byproduct of energy PRODUCTION at the turbine.

Heat goes out as electricity.

For compressed air as an energy storage medium see for example:

http://en.wikipedia.org/wiki/Compressed_air_energy_storage

In other words, as I tried to relate earlier.

This is a "Stirling Engine" in principle.

Instead of using the pressure developed from heating and expanding air with a pressure differential and "displacer" (not a piston)so as to drive a piston and crankshaft and whatever load is put on the engine the high pressure air is stored for later use to power a turbine.

The "waste heat" of the stored hot compressed air can be utilized to help maintain the temperature differential.

The compressed air is eventually released and used to power a turbine generating electricity.

The byproduct of the turbine generating power is, theoretically, very cold air.

(theoretically for this untried system that is, though it is well known that this works, ref. turbo-expansion, air-cycle refrigeration, gas liquefaction etc.)

If the cold air leaving the turbine is colder than the effective sink, then it can be used to scavenge problematic heat at the sink.

To help ensure that this happens the pressurized hot air can be pre-cooled back down close to ambient or even below ambient before being released into the turbine.

The turbine could be situated IN the lower half of the displacer chamber or just under it and so reclaim heat reaching the sink for power (electricity) production.

IMO, if such a System can work, it should be possible to get it working with a model engine comparable to a small LTD Stirling Engine, videos of which can be found on YouTube and elsewhere. Such engines are said to be capable of operating on as little as 1 degree temperature differential.

Theoretically, If this has any chance of working, I think it might work without the turbine, (Just a throttle, valve, choke point or "kink" in the tubing to hold back the compressed air rather than a turbine nozzle) but in such a case there would be no power output. (Similar to the "drinking bird" which "powers itself" only.

Theoretically, the addition of a turbine converting additional heat to electricity should serve to increase the temperature differential, that is, lower the temperature of the sink more effectively than a heat exchanger.

Last edited: Jul 4, 2012
19. ### Tom BoothRegistered Member

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I should mention that my references to additional "heat exchangers" above to remove excess heat from the system would be passive heat exchangers. That is, they would require no additional energy input. This passive heat exchange can be accomplished one way or the other simply by exposing the hot pipes (at a temperature above ambient) to the relatively cold Ambient.

Or at the turbine, when pre-cooled air is released into the turbine, ambient heat could be re-introduced to the expanding cold air at the turbine nozzle to increase the rate of expansion if the cold produced exceeds the requirements of the system.

I don't know as I'm being unrealistic about "too much cold" being produced.

Typically, compressed air expanding through a turbine can drop to temperatures well below freezing, even into the cryogenic range or to achieve temperatures cold enough to liquefy gasses.

Air cycle refrigeration systems have been considered inefficient primarily due to the fact that the temperature differential created is too extreme for conventional refrigeration or air-conditioning.

That is, it produces a lot of heat (heat that goes to waste in a refrigeration system) and extreme cold. Cold too cold for most practical purposes necessitating some mechanism to add heat back to the cold air produced.

This system however utilizes both the cold and the heat from the air-cycle.

In such an application where the "waste heat" can be utilized and the extreme cold is desirable (flash freezing, cryogenics, gas liquefaction etc.) the efficiency of the air-cycle is at least comparable to other refrigeration systems.

20. ### Aqueous Idflat Earth skepticValued Senior Member

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6,152
Tom,

It was you who wanted to engage the subject of the ammonia absorption cycle. You brought it up believing it would rescue your device from not having compression. That problem still remains, and until you come up with an energy source, your device won't do anything. Also, you have to back away from the over-unity error you've made.

Phase change/affinity/refrigeration

As I said before, the ammonia absorption cycle relies on the natural affinity between ammonia and water. You compared this to the hygroscopic nature of dry salt. That would describe a change of state from solid to liquid. With ammonia, it’s a change from gas to liquid. This is demonstrated in an ammonia fountain, a common chemistry lab demo:

The consequence is that the ammonia is now in bulk form, similar to being compressed from anhydrous gas to liquid, only without the need for a compressor. The difference is that the water and ammonia dissolve one another and form aqua ammonia, or aqueous ammonium hydroxide, which freely dissociates into ammonium and hydroxide ions. Except for this chemical alteration, it is functionally equivalent to the phase change that occurs just below the boiling point, for purposes of refrigeration. Simply stated, a lot of ammonia molecules are now compressed into a small volume. What we need, though, is liquid anhydrous ammonia, since this represents our true phase change which will provide refrigeration upon expanding back into a gas. This is accomplished as follows. The aqua ammonia is pressurized using a pump, and then heated to drive off the anhydrous gas from solution. The hot pressurized anhydrous ammonia gas is then sent though a coil where it condenses at ambient temperature into pressurized liquid anhydrous ammonia. This is the substance which, when passed through an expansion valve, will expand back into anhydrous ammonia gas, with a concomitant drop in temperature. Ideally, this temperature, times the number of moles produced, times the universal gas constant, establishes the amount of heat that the system will remove from the space being cooled.

Thus the automatic phase change that anhydrous ammonia undergoes upon surface contact with water has been exploited to eliminate the compressor that would otherwise have been required to produce pressurized liquid anhydrous ammonia at ambient temperature. This is what engineers call a mechanical advantage. That is, the somewhat troublesome compressor has been replaced by a pump and a heater.

Refrigeration without compression

This is a diversion from the focus, which is that you need compression in your device in order to do work. You brought it up thinking that heat compresses ammonia in the absorption cycle. In the conventional applications heat is what regenerates the anhydrous ammonia and pressure is supplied by a pump as described above. Aqua ammonia would not be brought to a boil per se without producing water vapor, which will recombine with the ammonia gas, defeating the purpose. In fact the systems will make provisions to remove moisture from the vapor. In the explanation I gave above, a pump pressurizes the system, and this satisfies the “power stroke” function of my earlier post.

However, let’s look at the simplest imaginable way to exploit ammonia-water affinity without a pump at all. This is how the "icy ball" works. It's from the early days of refrigeration, and I suspect Tesla either had one, or else was familiar with them. This was what came to mind when you conferred the task of pressuring the system to the heat source. So that's why I limited my earlier remarks to this type of cycle. In any case it's probably worth your while to study the icy ball, since it's about as rudimentary a device as may be conceivable, insofar as refrigeration is concerned. Plus, it may help you understand thermodynamics a little better. Here is a user's narrative on how to use an icy ball.

Pressure v temp

You brought up the ammonia cycle to refute my statement that your device cannot cool air without a power stroke. Obviously you could burn fuel and use the IcyBall method, that is, without a pump. Again, you are not proposing this, so my statement stands, as I am pointing out to you the fault of the current design, not some other one. To be clear, this device, and no other, which you believe cools air by some process not yet defined, which rpenner called “magic”, and Billy T called “over unity”, purports to cause air to expand and this is how you think it will be cooled. Again: you cannot “cause” air to expand at ambient temperature by any means other than forcing it to do so by compression or suction. Again, this is for the current device which you say expands air and cools it. You are not evaporating a pressurized ambient temp refrigerant, therefore, you need to furnish a power stroke. Nor are you burning external fuel, nor any energy source which produces a net energy (see below) therefore my statement stands.

Tesla

You mean, you wish Tesla had it right, that water in its lowest state were merely hydrogen and oxygen. In that case we'd have free hydrogen fuel and we'd all live like kings. By the same token life would never have arisen, as things would keep vaporizing. Obviously he was either mistaken or had something else in mind that didn't come across. This is the same man who discredited Edison and Einstein and who believed high voltage electricity could be transmitted like radio and received afar, to power ships and the like. He was given to making press releases to announce discoveries for which he didn't yet have evidence, which never went anywhere, and he gave titles to some of his writings announcing that he was brilliant. Whether these are a reflection of his mental condition, or as a branding strategy, or whether these reflect a cryptic humor, is a question for the history forums. It certainly has nothing to do with the plausibility of creating a self-acting engine, which is over unity and therefore impossible.

The only way you may convince yourself of this, other than trying to understand what folks here have told you, may be to sign up for some science courses and try to get a handle on the laws of thermodynamics. Labs are an important part of the curricula, because you are confronted by the harsh reality of nature, and the more you try to force the square peg into the round hole the more you become convinced you're doing something wrong. It's about then that you realize that these are not stubborn institutionalized scientists who are misleading you, but rather, they are folks who are coming back down the trail as you ascend, warning you of the slippery slopes ahead. It’s as simple as that.

Displacer v piston.

This is from your post #143:

To "create a pressure differential from the temperature differential" is to be a piston, by the conventional term. It takes energy to "cause the air or gas in the chamber to alternately expand and contract". Otherwise, the device uses up what you supplied at the get go, and it either begins behave like a piston, because you designed it as such, and it moves a little then peters out because it's designed for over-unity, or else it never does any of what you say above, because it cannot develop and sustain any pressure to change the volume as you assume here.

There's no compressed hot air, just ambient temp and pressure. There's no compression without a piston. There's no cooling of ambient air other than by your insertion of cold air from an outside energy-consuming refrigerator. Air does not "compress itself". This is the kind of statement that smacks of perpetual motion. However, if you simply mean PV=nRT, i.e., that pressure times volume is proportional to temperature, then the question arises: where does the volume reduction occur that you equate with “compression”? The compressed air must occupy a smaller volume. If you’re not sealing it inside of a confined space (piston-cylinder) then there is no volume to cause it to shrink and the air molecules that happen to have been cooled down by the A/C unit will simply blend with ambient molecules and nothing else will happen. Your expensively chilled air just leaked into the atmosphere without doing any work for you. You have to confine them into a piston-cylinder, and then, as the cool air expands, it will push the piston. And thus you are able to do a miniscule amount of work with your expensive cold air.

Once you assign the displacer the role of compressing anything, you are calling it a piston. You appear to be saying you will create low pressure on one side of the displacer-piston by cooling the air, while the ambient-side the displacer-piston begins at the higher ambient pressure, and then forces the piston to move until the pressure equalizes.

Volume

The wall you call a displacer moves up and down. This changes the volume of both chambers. It's the V in PV=nRT, the fundamental law that drives all of your thinking about how engine and refrigeration cycles work. So far you have the movable wall you call a displacer, but which you seem to be using as a piston. In any case, whenever it moves, it changes the volume of the two chambers. Refer back to your comments about compression, such as:

Here you are attempting to apply PV=nRT by noting that when you warm chilled air back to ambient, a linear change takes places in the PV product. If the displacer and turbine (the only possible ways air can leak in) are sealed tightly, then when you chill the lower cylinder you will lower the pressure, but only if V is constrained (the displacer is not free to sink slightly). On the other hand if the displacer were to sink in reaction to drop in pressure to 0.91 atm (from my earlier example), then you would have suction on the top side. In any case there is no compression.

The other scenario that makes even less sense is that you place the slightly denser cold air in the upper chamber and let it warm to ambient. In this case, if the displacer is locked in place and no leakage occurs a 9% pressure rise will occur in the top chamber as the cold air reaches ambient. But now what? You have converted dense cold air to slightly pressurized ambient temp air. For what purpose? Do you want it to drive the displacer down? Presumably so.

I may have finally stumbled onto what you've been trying to say all along. Maybe you think that the air I just mentioned is going to drop in temperature. If so, we can nip that in the bud easily. Let me go there. We start with cold air in the upper chamber. It is warmed to ambient and expands, pushing the displacer down. Now we are at the end of that cycle, the displacer has been shifted ever so slightly and the air in the upper chamber is at ambient temp and pressure.

You can decide what happens next when you tell me if the displacer compresses the lower chamber at all. You can even tell me it pushes the turbine by 84 mL. But what next? The cold air is gone. The temperature difference was converted into work, and now you are in a state of temperature equilibrium. Everywhere inside your device the air is at 25 °C at 1 atm. So nothing else happens.

This is why I said it makes even less sense.

Net energy

This remains your stumbling block. Your engine stops working as soon as you stop furnishing cold air. And it will only work at all if you follow very careful measures to prevent air leaks, and to convert the displacer into a piston of some sort. That is, if you intend to push the turbine, then you need to either lock the displacer in place and seal all leaks, while the cold air expands to ambient and sends 84 ml of ambient air past the turbine; or, you need to allow the displacer to push and compress he air in the lower chamber as the cold air in the upper chamber warms up and expands.

It remains your stumbling block since you fail to understand that energy is relative. It is only useful in its amount above or below a ground potential. To be clear, it is not the kinetic energy of the air molecules which can be exploited for energy, but the net energy which is the absolute value of their energy minus the energy of a second resource. “Resource” means an external resource, not one recreated in the machine that consumes the same energy. Note:

[font=”Arial”] A perpetual motion machine of the second kind is a machine which spontaneously converts thermal energy into mechanical work. When the thermal energy is equivalent to the work done, this does not violate the law of conservation of energy. However it does violate the more subtle second law of thermodynamics (see also entropy). The signature of a perpetual motion machine of the second kind is that there is only one heat reservoir involved, which is being spontaneously cooled without involving a transfer of heat to a cooler reservoir. This conversion of heat into useful work, without any side effect, is impossible, according to the second law of thermodynamics. [/font]​

21. ### Tom BoothRegistered Member

Messages:
61
First of all, on the positive side, thank you very much for the information about the "Icy Ball". Most interesting.

In researching this refrigerating system, through the information you provided I came across this do-it-yourself IcyBall site:

http://crosleyautoclub.com/IcyBall/HomeBuilt/HomeBuilt.html

Thanks again!

That I did, yes.

No, the intent was to refute your claim that "compression" (or pressurization) without a piston or power stroke is impossible.

The intended energy source is Ambient Heat. The very subject of this thread. I don't think that I have to "come up with" it.

The question is not where to find the energy source but rather, can one tap into or utilized it.

I'm afraid that you still don't understand the proposed system. (It is not "over-unity" IMO) You still don't understand the function of the displacer in particular. (where it all starts) and from there on you seem to have everything upside down and backwards due to your apparent refusal to inform yourself about the function of this very basic device. (the displacer)

Perhaps a drawing will help:

http://www.solar-facts.com/light-concentration/stirling-engine.php

Please note the displacer. Note how it is situated between "Heat Heat" and "Cool Cool".

Note the gap between the displacer and the chamber wall.

Note in particular the words and arrows pointing to the air space or passages or gap between the displacer and the chamber wall. It says: "Gas can move past displacer".

Look at the displacer here:

http://www.solarheatengines.com/200...g-1-performance-with-and-without-regenerator/

The displacer shown on this site includes "regenerators" and is similar to mine, or my intended design. That is, it has big holes in it. The holes, in this example (on the website - the link provided above) The holes are filled with loosely packed steel wool for the air to flow through.

There is No Possibility Whatsoever of such a displacer/regenerator effecting any kind of compression or of acting like or behaving like a piston.

It would be impossible for any high pressure or low pressure to develop above or below the displacer as the air passes right through it.

Note that in my design I have replaced the piston with a set of check valves. Otherwise, the function of the displacer is the same. i.e. "(the displacer) will move the air alternately from the heated to the cooled portion of the chamber. This will repeatedly heat and cool the gas causing it to expand and contract."

As I mentioned earlier, "expansion" in a closed container is the functional equivalent of "compression".

Sorry, but no. It is not "functionally equivalent to the phase change that occurs just below the boiling point, for purposes of refrigeration."

The ammonia fountain does not effect "refrigeration". Yes there is a slight pressure drop when the ammonia gas is absorbed by the water and some fluid is drawn into the "fountain" to take up the space previously occupied by the ammonia as it is absorbed. This does not effect refrigeration and could not even happen if the system were sealed. In reality Atmospheric pressure causes the fluid to rise due to the slight pressure differential created when the ammonia is absorbed. This is not "functionally equivalent to the phase change that occurs just below the boiling point, for purposes of refrigeration."

Congratulations!

OK. I have highlighted what you previously left out in your earlier descriptions.

It should be noted however that the pump mentioned here alone does not effect the heating and pressurization which allows the ammonia to condense into liquid.

You are confusing things again. The re-absorption or the ammonia is not a substitute for "the compressor that would otherwise have been required to pressurize liquid anhdrous ammonia at ambient temperature."

RE-absorption of the ammonia is the final part of the cycle. You are equating this with the start of the cycle (heating and pressurization).

When the ammonia and water are boiled and the ammonia is driven out, the pressure increases to about 250 Psi. Under such high pressure the ammonia is easily cooled and condensed into a liquid. Re-absorption later in the cycle if anything reduces pressure. It is apples to oranges. Your so called "automatic phase change" at the end of the cycle is no substitute for the pressurization effected by boiling (application of heat) at the start of the cycle.

Not quite.

:bugeye:

The "IcyBall" is simply "batch refrigeration".

Otherwise the cycle is the same. Heat the ball containing ammonia and water. Ammonia gas is driven off. (incidentally, along with some steam which quickly condenses back into water and drains back down into the ball leaving ideally, pure ammonia gas under high pressure. The pressure from steam, ideally, does not contribute much pressure. The idea is to heat the mixture SLOWLY so just the ammonia is driven off.)

As the Wiki article you cited explains:

This is only the first half of the cycle. Heating the ammonia raises the pressure to 1.72 Megapascal which, according to an online pressure converter translates to the more familiar 249 Psi. That's a lot of pressure. You seem to be overlooking this or you are trying to dismiss it as irrelevant, as if the ammonia is simply "evaporated" and reabsorbed with no pressurization involved.

I am proposing the functional equivalent using air as a refrigerant rather than ammonia. When the displacer moves, the air is heated and the result is pressure. In an Air-Cycle system, however, no phase change occurs. Otherwise this is functionally equivalent to heating and expanding ammonia so it may pressurize itself. It can then be cooled and condensed.

Likewise, air can be pressurized by heating in a closed container.

The expansion and pressurization of the ammonia is more dramatic but the basic principle is the same.

Or heating in a restricted environment. You can pressurize a plastic coke bottle by leaving it in the sun (with the cap on) to heat up.

The "external fuel" or "energy source" is Ambient Heat.

As I said before, Tesla's mention of decomposing water into hydrogen and oxygen was for illustrative purposes only. You obviously have misunderstood him and taken his words too literally.

Yes, he had something else in mind. Whether it "came across" or not depends on whether you understood his point, which you apparently did not.

Perhaps he was right. His tower was torn down by J.P. Morgan and Morgan had him blacklisted so he could get no more funding because the energy produced could not be metered, not because anyone thought it wouldn't work.

Your entitled to your opinion. However we would probably not be having this discussion without Tesla's AC current and other inventions.

Please look into how a displacer functions in a Stirling Engine.

As far as "where does the volume reduction occur that you equate with 'compression'?"

There is no mechanical "compression" by any piston.

If you are familiar with PV=nRT then you should know that heating a volume of air in a closed container (Container A) is equivalent to compressing a larger volume of cooler air (container B) down to the size of the container (A).

The "confined space" is the displacer chamber.

"then, as cool air expands, it will push the piston" ?

Huh ?

No.

No, the displacer is not a piston. Nothing "forces the piston (sic. displacer) to move"

The displacer moves or "displaces" the air. (Air moves around or through it) The pressure, high or low does not have any effect on the displacer. The pressure exerts no force on the displacer. The air pressure changes effected by the movement of the displacer have no effect on the displacer itself. Air in the displacer chamber moves freely around and/or through the displacer.

There is only one "chamber". The displacer is inside this ONE chamber. There is no change in volume.

No, it is not a piston. It is not being used as a piston.

There is only ONE chamber. The volume of the ONE chamber does not change any more than the volume of the atmosphere changes when you wave your hand in the air. Like the displacer, your hand just takes up space. The air cannot occupy the same space as your hand so your hand "displaces" the air. Do you know the definition of "displace" or the concept of "displacement". Two things cannot occupy the same space, therefore the "displacer" displaces something else. In this case the air in the displacer chamber.

:bawl:

No. There is only one "displacer chamber".

Let's say the chamber is 5 inches in diameter (ID - inside diameter). The displacer is smaller, say 4 and 1/2 inches. There is space on the sides of the displacer for the air to simply go around it. Pressure changes do not drive the displacer up or down or in any other direction.

There is no "upper chamber".

No, the air is heated and it expands, true, but it does NOT push the displacer down. The expanding air goes right around and/or through the displacer. There is only ONE chamber. The air in the entire chamber heats and expands. There is no possibility of the displacer being pushed down as at this point, if the air is at the top being heated the displacer is already at the bottom, as far down as it can go. The heated and expanding air cannot do anything but relieve some pressure by going out through the check valve into the tube on the other side of the check valve.

The displacer has not been "shifted slightly". Heating and expanding the air has no effect on the displacer.

There is no "lower chamber". The displacer is occupying what you are calling a "lower chamber", however if there is some residual air left in the "lower chamber" (sic.) then it is also pressurized.

Something else does happen. The displacer moves up forcing the air in the ONE chamber down to the bottom. The air is now insulated or removed from the heat source. Residual heat is absorbed by the sink to which the air is now exposed due to the displacer moving up. The displacer is no longer insulating the air from the sink. So now the air cools and contracts.

The hot pressurized air which went out through the one-way check valve cannot be drawn back into the chamber because it is a one-way valve.

So as the pressure drops the other valve opens and some fresh ambient air is drawn into the chamber.

The changes in pressure cannot push and pull a piston as in a Stirling Engine because there is no piston and the displacer cannot serve the function of a piston in any way so the expansion and contraction push or pull open the check valves.

The displacer cannot be converted into a piston. Please get that notion out of your head. The displacer is not a piston. It cannot serve the function of a piston. It is, in many small Stirling Engines, only a block of Styrofoam with holes in it. If you attempted to use it as a piston it would break apart.

There is nothing "spontaneous" about the way this engine is supposed to convert heat into work, any more than a Stirling engine "spontaneously" converts thermal energy into mechanical work.

And thus the controversy. Or lack thereof on the subject.

Tesla took this issue to task.

Heat from ambient is not a finite source of energy. Take heat out of the "reservoir" and convert it into some other form. You don't have to put the heat back in order to use it again. The reservoir of heat energy in the ambient medium cannot be depleted.

Strictly speaking, the 2nd law of thermodynamics applies only to isolated systems in thermodynamic equilibrium.

An ambient heat engine is not and cannot be IMO an isolated system.

The atmosphere is heated by the sun and is radiating heat into space continually. True we live in a kind of reservoir of Ambient Heat energy, but if heat can be converted and the supply is unlimited, finding a way to dump excess energy somewhere would not necessarily be a violation of the second law.

An "isolated system" does not allow transfer of mass through the system.

Compressing air from the surroundings involves mass transfer. Expanding air back to atmosphere involves mass transfer back to atmosphere.

If such a system could be made to work, nobody would consider it a violation of the 2nd Law of thermodynamics. IMO.

Last edited: Jul 6, 2012
22. ### Tom BoothRegistered Member

Messages:
61
Additionally, if this arrangement could work, there would indeed be a "side effect". At least in the short term.

That is, Warm Ambient air would be drawn in. The heat "wrung out" of it. The heat would be converted into electricity. The spent cold air with little energy would be returned to the atmosphere.

The "side effect" would be an imperceptible slight cooling of the local surrounding atmosphere. The cooler air released back to the atmosphere, and blowing in the wind to parts unknown, would in time be reheated by the sun.

23. ### Tom BoothRegistered Member

Messages:
61
Maybe look at it this way.

Suppose we have a Stirling Engine driving a nearly frictionless conveyor belt.

The engine is housed in a refrigerated room.

The engine runs the heat pump that effects refrigeration to keep the environment cool.

On the conveyor belt driven by the engine are some rocks.

The belt makes a continuous loop going from the inside of the refrigerated room to the outdoors into the sun.

The conveyor is situated in a way that the hot rocks deliver heat to the engine.

When the heat in one rock is partially exhausted the belt moves and the rock partially cooled by the engine is replaced by another hot rock coming in from outside where it was heated by the sun.

Cold rocks, their heat energy having been spent make their way back out into the sun where they are heated again.

Since there is mass entering and leaving the system, nobody would look at this and say it was "perpetual motion". It is just the utilization of indirect solar energy.

You aren't so much, or you are not exclusively delivering heat to the engine but rather a mass. Hot rocks.

The rocks can hold more heat than the engine requires to keep the conveyor belt moving as well as operate the heat pump.

Since there is mass transfer in and out of the system it cannot be considered a closed or isolated system. The 2n'd Law does not apply.

In the proposed "Ambient Heat Engine" we simply replace the hot rock with a volume of solar heated ambient air.

The conveyor is replaced by the heat driven "displacer" which takes little energy. The displacer uses some of the heat derived from the incoming packets of air mass and acts as a "pump" to convey or draw in more "hot Rocks" or rather, more volumes of heated air mass.

More heat/energy can be derived from the hot air masses to keep the displacer moving than it takes to move more of the packets of hot air in.

Just as the engine in our example can get more energy out of the hot rocks than it takes to power the conveyor belt.

Quantities of solar heated air (air molecules - mass) contain more heat energy which can be utilized by the engine than the engine has to expend to draw more of these packets of heated air mass in.

In other words, we use heated air (which is considerably easier to move than rocks) in place of our rocks.

Nobody would balk at the Stirling Engine using indirect solar energy or solar heated hot rocks as a power source and call it "perpetual motion". Obviously it is just solar energy. Solar energy temporarily stored in the rocks.

Ambient heat in the air, IMO is just indirect solar energy temporarily stored in the mass of the atmosphere. If a way can be found to utilize it, there would be no reason to cry foul as far as the 2nd law of thermodynamics is concerned.

There are other things to consider, and that is, in all of my reading in regard to heat engines and thermodynamics and the 2nd law, Statements regarding the impossibility of a heat engine deriving heat from a single "reservoir" always assume that there is some heat source to drive the engine and that Ambient is used as a sink.

In such a case, the hot reservoir (above ambient) is used to run the engine. Some of the heat energy is converted. Some heat is always lost. There is therefore less heat at the end than there was at the beginning, so even with a "perfect" refrigeration system, you simply cannot, under any circumstances pump the heat back up to the hot reservoir to be reused. It is no longer available.

I have not come across any thermodynamic formulation where the reverse is assumed to be the case. (Ambient as the source rather than the sink).

In such a case, where ambient is the heat source, the fact that some energy is converted and lost becomes an advantage rather than a hindrance.

The problem of requiring a "beyond perfect" heat pump to pump non-existent heat that has already been converted into some other form back to the hot reservoir to be reused does not exist.

The problem becomes simply removing energy that has not been converted as the ambient heat reservoir is effectively inexhaustible so heat does not have to be returned to it.

The fact that heat is lost in the process of conversion to some other form is to our advantage.

The more heat converted, in fact, the less there is left over to pose a problem as far as how to remove it.