New Low Cost Way to Compress Air

Bullsh-t has to be distilled twice to make it this pure.

<...The pressure rises above tank pressure...>

Oh, yeah?

The transient pressure does go over tank pressure because of compression heating. Same as a normal compressor, if you could save the heat produced in compressing air your cost would go way down. The math proves it, there is a self-explanatory spreadsheet as well as sketches on this site:

http://cannedthunder.blogspot.com

This happens in a conventional compressor in a way that is not useful. Heat has to be dissipated as quickly as possible from the mechanical compressor so it doesn't self-destruct. Compressing air is a very violent activity that we take for granted, and the math is so simple that people won't even look at it. The combined gas law and the adiabatic equation are used in steps as taught in an air brake manual.

If you bother to look into this you will be satisfied that I have at least put a lot of effort into figuring it out according to standard engineering equations. If I've made a mistake I want to know about it. And yes of course it sounds crazy. I studied compressed air for 29 years before it suddenly occurred to me: what happens if you compress air in the pipe instead of in the compressor? According to the texbook, if there's a drop of oil or a little water in the pipe, the pipe could burst.

Luther

Oh yeah?

How's this for a reason. Heat can only travel from a higher potential (higher temperature) to a lower one (lower temperature). The only way ambient heat can heat up your system is IF the compressed air is below ambient temperature.

Those kinds of generalizations are true where they apply and like all generalizations they get mis-used by being tossed out at anything that moves.

Are you saying that heat pumps can't heat a house in the dead of winter? It can be arranged! Heat is heat, and the compression heat plus the ambient heat added to it increases the total pool of energy available for use. This was not obvious on the day that the laws of thermodynamics were proven to be true, now let's use the law correctly and not try to stifle new ideas with it.

Ambient heat is not heating up the equalizer in the tank. Compression of air is what produces the heat. Ambient heat just adds to the total pool of energy available from the tank, once the new air is tricked into the tank.

This is not in violation of the 2nd law, it's just an air compressor. The compression heat is being used, not wasted. Just imagine, a compressor inside its own air tank.

Luther

<...heat pumps can't heat a house in the dead of winter...>

They work by refrigerating the land outside and dissipating the heat within the building, Captain. For the refrigeration step to work, there has to be a process fluid at a lower temperature than the land outside that, upon compression, achieves a higher temperature than the building so that the heat can dissipate within it. The principle is well-established, and entirely supported by the Laws of Thermodynamics.

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

Even earlier the greeks had a proverb:

"If you keep your mouth shut you can be considered a philosopher!"

It very much applies to your text. Make a better nalysis and since you have some knowledge of thermodynamics you will recognize your self that it will not work as you think.

Sorry.

OK, a better analysis. I already have made one and you haven't looked at it.

Sorry, if the discussion doesn't interest you. I want to see, in response to my math and theory, some math and theory of your own to back up your remarks.

Luther

Look at the thread:

Equalization Pressure of Two Air Receivers

You will find some interesting aspects of the problem and also "some math and theory of your(my) own to back up your remarks."

Glad to help you to better understand the problem, although not what you have as scope the problem is the same with different initial conditions and has to considered with same basics.

Best regards

Nick Name

PS.: In general when I write something I have a base for it.

Thanks for the link.

In my application the smaller vessel is much smaller and much lower in pressure, and is inside the larger vessel. So it should equalize in a split second.

The topic I tried to bring up is that the pressure will actually over-equalize. The air in the target vessel will be compressed adiabatically instantly and the heat will raise the pressure inside the target vessel over what the "equalized" pressure would eventually become if the valve were left open long enough for thermal equilibrium to take place between the two vessels.

Once the heat of compression has spread throughout the two vessels and all the air has stopped moving, then the generalization about pressure equalization will apply: the pressure of the new single volume will be less than what the higher pressure started out to be in the source vessel before the valve was opened to put them in communication.

When I write something, I also have a base for it. My basis is the combined gas law and the adiabatic equation.

Skeptics would argue that the pressure of equalization is between the two initial pressures. I agree. If you wait for complete equalization. I am talking about a large pressure differential, a large difference in volumes between the two vessels, and a process that is interrupted after the initial rush of air into the smaller vessel so that compression heat cannot return to the source vessel.

That is unbalanced equalization, a transitional state that takes place before thermal equilibrium has been reached.

The sketch, the spreadsheet and other details are now easy to get to on my blog, whereas before I had not figured out how to post them so others could look at them.

Luther

http://www.cannedthunder.blogspot.com

Oh yeah?

Thermodynamics is sufficient theory, and it isn't CR4-user-specific.

OK, let's assume that both tanks are at atmospheric pressure and room temperature.

Walk us through the start-up procedure. Take us to the point that the system is producing enough heat to sustain the process.

Everyone knows that scuba tanks get hot when filled by partial equalization from a larger, higher pressure vessel. If there's any water in the tank, it can turn to steam and burst the tank if the tank is filled too quickly. And if you watch the gauge after a scuba tank is filled quickly, it will go down after filling as it cools, till ambient temperature is reached.

Put a very small, empty pressure vessel inside a relatively very big one that is already charged to maybe 150 psi or 10 times atmospheric pressure. Provide the small one with a big valve that opens and closes quickly. Open the valve quickly, the small tank is slammed full of air. I assume adiabatic compression since the resulting compression heat has no time to go anywhere. The small tank can be insulated also.

Because the small tank is filled so quickly, many times faster than a conventional compressor can fill it, the heat builds instantly to the adiabatic extreme. This is very hot. It is the same amount of heat produced by a compressor making the same pressure in the same air at the same speed. Lots of heat.

If you let it sit with the valve open, thermal equilibrium will be reached after some time between the two tanks and the big tank's pressure will go down slightly so the small tank's pressure can go up a lot to match it. But that's not what happens. I'm talking about the transient range of conditions after filling and before complete equalization has been reached. I'm also talking about equalization between extremes, which is not done much since it's dangerous. Because of the heat.

The valve closes as quickly as it had opened and all the normal heat of compression is trapped in the small tank. The small tank or equalizer is fed through an intake check valve by atmosphere from a compressor and it is provided with a special check valve that discharges into the tank.

The discharge check valve has a strong spring so that air doesn't just spurt or dribble through it. At a certain elevated pressure, all the air bursts out of the equalizer en masse, as a unit.

This leaves behind a clear equalizer for more atmosphere to enter. Works like a pulsejet or tuned exhaust on a two-cycle engine. This is not new theory, just a unique application of sudden equalization between very different volumes and pressures.

It's not obvious if you don't think it through, but the math proves it. I replaced the spreadsheet with one that is self-explanatory and added more description as well as sketches of the basic device.

http://cannedthunder.blogspot.com

Thanks for all the comments,

Luther

Oh yeah?

<...scuba tanks get hot when filled by partial equalization from a larger, higher pressure vessel. If there's any water in the tank, it can turn to steam and burst the tank if the tank is filled too quickly....>

So why doesn't the steam pressure inside the scuba tank oppose the pressure of the device that is filling it until the steam condenses, then, thereby reducing the incoming flow?

And why doesn't the scuba tank filling system have some sort of overpressure relief so that bursting tanks is so unlikely as never to happen? The hazard in this case is low-flying scuba tanks!

Build a better mousetrap, and the world will beat a path to your door. No one seems to be beating a path to this particular door. Must be for lack of shrewd venture capitalists that can't figure out the concept. A misfortune. (That's one way to look at it.)

Another way is that this just ain't gonna work. Even if you open a BIG valve between the chambers, equalization will not be instant. As equilibrium is approached, the inrush rate will slow down. There might be some "inertial overshoot," but probably not enough to capture much useful effect.

The best way to approach this would be to produce a working model. A somewhat less optimal way would be to produce a You-Tube video. The first would be investment-worthy; the second might at least be entertaining. With a clever IPO, it might even garner some working capital, which could best be worked by absconding with it.

After all, separating fools from their money is a noble deed: If nothing else, you can spend it better than they did. Sort of like J.Z. Knight (Ramtha), or televangelism.

For your "might" and "probably" I offer you the combined gas law and the adiabatic equation.

P₁V₁/T₁ = P₂V₂/T₂ = P₃V₃/T₃ = constant (combination of Boyle's Law & Charles' Law)

T₂ = T₁(P₂/P₁)^(n-1)/n (adiabatic equation solved for final temperature in terms of pressure changes; n = 1.406)

T₂ = T₁(V₁/V₂)^(n-1) (adiabatic equation solved for final temperature in terms of volume changes)

I once opened a valve for no reason, daydreaming. ONCE. I guarantee that equalization was instantaneous enough for government work, and I'm lucky I survived. There was an actuating cylinder without a load on the rod, which was pointed at my left ear, and the rod extended faster than I could see it. I could hear it, though; it sounded like a bullet whizzing past my ear. If my head had been an inch further to the left, equilibrium point would have equalled a free lobotomy.

The size of the valve can be very large in relation to the small vessel but more importantly, the small vessel contains about 1 atmosphere and the large vessel contains about 10 or more atmospheres. Most applications of pressure equalization do not deal with large high pressure vessels suddenly filling much smaller vessels containing only atmosphere. But player pianos (air powered computers that played pianos automatically) operated on a small pressure differential and the notes were played instantaneously enough to make precision music.

An equalizer inside a tank could be 1" diameter and 6" long, which is about 0.002727 cu ft volume. The tank it's in could be say 16" diameter and 48" long, or about 5.585 cu ft volume. The difference in volumes is about 2048:1. The average pressure in the big tank will go down a fraction of a degree while filling the equalizer, while the temperature will go way up in the equalizer.

The first thing that happens when the valve opens to communicate the two vessels is that for a moment the temperature will go down in the equalizer because it is nearly empty. As soon as the temperature reaches starting conditions, the pressure in the equalizer starts to go over tank pressure. That is necessary in order to prevent a violation of the laws of thermodynamics. Or do you believe that my device is destroying energy? Have you actually done the math? Is that where you get the "might" and "probably"?

You're right about one thing: it has to be built. As for You-tube, I don't have time for it.

http://www.cannedthunder.blogspot.com

Luther

You made the remark that your vessels have other dimensions, it is true but the physics are the SAME.

In all your equations one parameter is not present: TIME.

Write the equations for the TIME dependency of pressures and make a simulation of the pressure in the small container versus time, as it is a theoretical model you may consider the valves with infinitely short reaction times.

You could use a spread sheet and the Runge - Kutta 4th degree algorithm for the integration of the differential equation you will write.

It is a DYNAMIC process you want to determine with STATIC equations. It is not enough since you modify the air MASS in the small container so that your equations are not any more valid. The example you give is not the right one since you had a low load (only inertia and friction) the pressure drop at the valve was almost the full line pressure so that the flow was very important. It is a pity you did not have a pressure sensor and a stroke transducer connected to a recorder to visualize the 2 parameters as time functions you would better understand what happened.

You did not read, did not understand or did not want to understand the link I gave.

As long as you do not demonstrate at least on paper that it works nobody will accept it. A simulation will be good for you to see that it does not work as you expect it.

To your informations there are so called shock tubes where adiabatic waves are generated based on same principle as you want to use: burst of a membrane placed between container and tube.

I am grateful for the information you have provided me with. Since I'm not an engineer and don't know calculus it won't help me right now, but I have saved it and will try to deal with it one idea at a time. No doubt there is a way you could explain it to me more simply, but I'll muddle through the best I can. I've heard it said that calculus is just compressed algebra, that algebra can do the same thing but more tediously. I've used spreadsheets to compute many small increments of change, since the spreadsheet can reduce the tedium, and gotten the same results as the calculus would have gotten if I had known how to use it.

It sounds like you might be saying that your reason for rejecting the idea is that the air won't transfer into the small container fast enough to raise its temperature. This sounds impossible. Filling scuba tanks through a hose and a relatively small valve can get the air very hot if the filling is done quickly, and afterwards the pressure goes down as the tank gradually cools.

Maybe there's someone watching this discussion who can paraphrase your argument for you, if you don't know how to say it to a non-engineer.

Until I can find the answer I can't see why it won't work. It is not obvious but when you see it, it seems like common sense. I suspect that when I figure out how to do the equivalent of the calculus you suggest, I will find that I was right. I am skeptical enough myself to not build it till this discussion or one like it reaches a reasonable solution in black and white.

Luther

"It is a DYNAMIC process you want to determine with STATIC equations. It is not enough since you modify the air MASS in the small container so that your equations are not any more valid."

The equations I quoted previously are not enough, as you say, because air masses are being combined. So P₁V₁/T₁ = P₂V₂/T₂ is used, but in steps. Because it refers to a single mass of air. So the two masses of air are conceptually combined and then treated as a single mass of air so through a series of steps using the combined gas law, you get the result of full equalization. A new value PV/T.

To this is applied the adiabatic equation to find the transitional states that lead up to full equalization. It's all spelled out in detail on my weblog and makes complete sense. The result is a range of results, new pairs of PV/T conditions for the big and small tank, that reflect adiabatic compression and add up to the full equalization PV/T result.

The end result of the steps method can be checked with the equations below for pressure equalization. The one for full equalization comes from an air brake manual, the other one I figured out but it checks out too. It doesn't include adiabatic air compression values so it works as a check of the steps method, but to get the right answer for adiabatic compression of air, you have to go through the steps. Then use the "unbalanced equalization" equation below as a check.

Full Equalization: P₁V₁/T₁ + P₂V₂/T₂ = PV/T (combining two masses of air results eventually in the new stabilized condition, which is the sum of the two initial conditions).

Unbalanced Equalization: P₁V₁/T₁ + P₂V₂/T₂ = P₃V₃/T₃ + P₄V₄/T₄ = PV/T (combining two masses of air results in a range of pairs of new transitional, transient states which add up to the same value as the sum of the two initial states).

These equations are not imaginary, they are pressure equalization equations. They stop trains.

I don't know why you can't use algebra to do this, if I knew calculus I'd be happy to use it. Nevertheless I am looking up the terminology you presented in case there's any hope I can figure out what you're talking about. I am interested in the time element but don't know how to deal with it yet. Simpler description is needed, my education doesn't go beyond intermediate algebra.

Luther

Your problem is the same as many inventors met. You have an idea, qualitative, which you cannot quantify not having the skills to do it so that you believe in your idea based on wrong basis. If you are not able to do it yourself (as it appears) get a consultant able to make the DYNAMIC analysis and show you how the process runs. It is a complex analysis and it cannot be done for free. Or may be an other participant has the tools and the skills to do it. I made it once that is enough.

OK, I don't have an argument with that, I just don't know what it means. Can it be done with algebra or not? I can figure it out if it can be done with algebra. Can you define "dynamic analysis"? Actually it can be done for free, if it can be done by me. I still don't know if I can do it. I don't think calculus is needed, why would it be?

Luther

Then as the low pressure tank heats up, the high pressure tank must cool down.

"As equilibrium is approached, the inrush rate will slow down. There might be some "inertial overshoot," but probably not enough to capture much useful effect."

Even though you sound uncertain of yourself, I thought about it.

You said one thing that scared me for a second, but here's my response.

Picture a big, heavy pendulum, swinging in a wide arc.

On its first swing downward, just after being released, it approaches its equilibrium point, where it would be hanging straight down. As it approaches this point, its forward progress slows and at the point of equilibrium it just plain stops dead as a doornail, or maybe it overshoots a couple inches and whimpers back to where it belongs and then stops.

Kind of impossible, isn't it?

Every wave motion on earth is a case of overshooting equilibrium. In fact, equilibrium is hard to find on this planet, not counting my wife right after dinner.

Luther

Bad analogy, I think.

"Bad analogy, I think."

Why do you think so? Air is a spring, it has momentum when it moves, its pressure goes down when it moves, it is compressible. It doesn't "fill" a vessel, it keeps moving until it's made to stop, then it turns around and goes the other way, only gradually coming to rest at equilibrium, like any spring.

Speaking of analogies, here's another.

In general, we're talking about using part of the energy in a pressure vessel to somehow get a fresh charge of fluid into the vessel without a mechanical pump squeezing it in. With steam boilers, this has been done since 1858 when Henri Giffard invented the boiler injector. After the device was proven capable of putting fresh water into a hot boiler without a water pump to pressurize the water first, it was still being argued that the injector was impossible. Or that it was perp. mot., kind of silly don't you think, since perp. mot. is impossible, and yet the injector was already available down at Boilers R Us.

Don't accuse me of saying that a boiler injector can be used on an air tank, I am just bringing it up as an analogy of a process that is considered impossible because it is not obvious, by skeptics who enjoy ridiculing new ideas because it's easier and maybe more fun than breaking out the slide rule and proving someone wrong the right way. To me, the jeering of mental doubt aimed at anything that defies the status quo just indicates cliquishness and laziness; a trained brain is a useless brain if it's in a recliner sneering.

The last point for today is that I have presented this concept as an ideal, a starting place. That is the foundation, and it has to be defined clearly and proven out on paper, exactly what it will and will not do. Then from a corrected ideal, a better idea has a foundation to grow. For example, some of you seem to be saying there won't be enough time for air to go into the small vessel and raise its pressure. Then that can be solved by addition of another energy source, but the process has to be described by mathematics, not by mental doubt and sarcasm.

Don't assume I am looking for something for nothing, I am just convinced that scientific discovery and compressed air parted ways a long time ago, without good reason. That compressed air's potential has not been tapped. If I can find exactly where my idea stops being a good idea and starts being wrong, then I'll be able to guess how it might be improved. According to standard equations for pressure equalization, which have been stopping trains since before Westinghouse, my idea is solid.

Did you know that before Diesel compressed his air/fuel mixture with a piston, he compressed it by adding compressed air to it? I hear they're thinking of going back to that system.

Luther

It's a bad analogy as the swing of a pendulum is a second-order system; it self-oscillates as it has inertia. First-order systems don't do this.

A valve on a pressure vessel is an example of a first-order system. The flowrate through the valve is a function of the pressure difference between what's inside the vessel and what's outside of it. No pressure difference = no flow. That's it.

I have to make a retraction of what has gone before so I can clear the way for better idealizations of the in-tank equalizer.

The idea that a surge of tank energy will drive the equalizer pressure above tank pressure seems wrong once viewed in the context of this simple law of nature: a lower pressure gas doesn't spontaneously flow into a higher pressure. I got hooked on the idea that equalization with tank air would cause the equalizer and tank air to arrive at equilibrium, which would then be bypassed in the equalizer because of the heat of compression. It is a superficial idea based on not thinking critically enough.

What really happens is that compression heating in the equalizer does take place when tank air slams into the equalizer, but it contributes to the pressure rise in the equalizer that only reaches the point of equilibrium and stops. My analogy of the pendulum is wrong because the pendulum does not encounter an increasing resistance as it moves toward the equilibrium point.

I could blame senility but it was really just carelessness and wishful thinking, wanting to be the discoverer of a new scientific principle.

That hasn't changed so I'll just say that the pressure equalization equations I have been learning are still valuable to the continuation of my work or play. Now that I know that the immediate result of mixing air masses results in equal pressures in both containers—barring other influences—the equations I was working on are now much better as there is no longer any fill-in-the-blank value throwing wishful guesswork into the math. Final tank and equalizer pressure are now equal and easy to solve. The only manually filled-in values are now the initial values of both vessels. The math might still be simplistic from an engineering viewpoint but I think it's a solid starting place for now. I have to work on the dynamics of flow per time, it is something I've never studied.

I have plenty of ideas for new cheaper ways to compress air, aided by the existing pressure in a pre-filled tank and a second much smaller tank or equalizer inside the tank that is fed by a compressor that works against lowered resistance, not against tank pressure. My favorite right now is a movable intake check valve to the equalizer, comprising a piston with a check valve in it. After equalization, an outside energy source pushes the equalized air the rest of the way into the tank. This comprises a compression stroke that is mostly delivery so the PV change work is very small.

I have worked out the math on that so will put it on the blog. I will post the simplified equations for unbalanced pressure equalization too, since it's still true that thermal effects take longer to even out than pressure equalization which takes place more quickly, or very quickly in an application like this where the two vessels are much different in size and initial pressure.

The most interesting aspect of unbalanced equalization is that if done in the tank as I suggest, the heat of compression is easy to conserve. That has always been the real ideal of what I'm working toward. A cheap way to compress air.

Thanks to everybody for their comments.

Luther

<...have to make a retraction of what has gone before so I can clear the way for better idealizations of the in-tank equalizer...>

Some of it or all of it?

The part I'm retracting is the part people were arguing against. I had wrongly assumed that compression heat would drive the pressure over equalized pressure in the target vessel. When I slowed my thoughts down, trying to imagine change per increment of time, I happened to see that I had missed something obvious. As soon as pressure is equal, flow has to stop. Then I saw that the heat of compression will be responsible for part of the pressure rise in the target vessel, rather than augmenting it.

It seems like a big deal to me that if this equalization takes place inside the larger vessel, the source of the higher pressure, then the heat of compression is easy to conserve.

And your suggestion that I build it is fine, but never in the 21 years since I thought up this equalization compressor has anyone told me what's wrong with the idea. Till someone tells me what's wrong with it, I can't afford to build it. Building it is the super-expensive way to find the errors in my thinking. I am posting this so that others might see it and build it for themselves. If they report back to me on their results, so much the better.

But until someone comments on the spreadsheet I can't even justify drawing it. My knowledge is not sufficient to say whether it's worth building or not. For now the sketch and spreadsheet on the blog are awaiting comment.

Thanks for your comments.

Luther

http://www.cannedthunder.blogspot.com

The Laws of Thermodynamics have been very aptly described by CR4's Stirling Stan as:

1. "You can only lose"
2. "You can't break even"
3. "This is the only game in town."

In 1858 Henri Giffard learned how to put fresh water into a hot, pressurized boiler with no moving parts, using part of the steam from that same boiler to do the job as the drive fluid in his injector. His injector was considered a paradox for a long time. It was even "proven" to be impossible after it was available to anyone who wanted to buy one. This is still standard technology, there are whole books full of variations on Giffard's boiler injector.

The injector itself is only about 3% efficient, since most of the energy in the steam can't be used to entrain water. But the system as a whole is nearly 100% efficient since the only loss is through leakage and radiation of heat. There is so little loss because the residual energy in the steam, the energy not used to entrain water, goes back into the boiler, still heat and still available.

The combined gas law transforms into the pressure equalization equation. This equation stops trains, how hard is it to do with air in 2010 what has been done with steam for 150 years?

I believe in the laws of thermodynamics, and here is one version of the law that says you can't destroy energy:

P₁V₁/T₁ + P₂V₂/T₂ = PV/T

The constant of the source vessel plus the constant of the target vessel equals a new constant for the combined air mass.

Luther

I did not want to interfere any more but I read some thing which makes me to do it if I rightly understood your statement: you think about this idea since 21 years!

In all this time even NOT being an engineer as you stated you had the time to learn step by step all the thermodynamics and other principles so that you could make the qualitative jump and under stand where the weak point in you analysis is.

I shall put it in 2 words you do not think energy balance and make similitude with other physical principles which are not valid. You do not think flow dynamics and do not take care of the meaning of "inertia" or lack of it. In fact you should go deeper in the study of physics if you intend to make a revolution in it. What I am VERY surprised is that the people who read your text did not react early enough and at least tell you (or write) that it is not correct because it is not complete. I wonder who supported you after reading your description. At least even if you are shocked by our negative comments you should take them the right way since it avoids a huge investment for nothing. Your example with the ejector is also not to extrapolate as an example that your idea is valid.

You cannot expect from a forum where the great majority of participants will give you as answer only internet addresses especially in the frame of our "bestest friend Wikipedia" (best being already a superlative the first word is special creation with the meaning "best of the best") to get all explanations one has to get by himself in day by day or even night by night working (during the 21 years the time for it was I am sure to be found). In fact, again, your problem is the discrepancy in knowledge requirement between qualitative idea and quantitative estimation of its feasibility, for the second phase know how is required not needed for the first and which you do not have but can, with a lot of effort, gain.

Good luck

Where I'm at in my learning process should not get you so upset. And you are not interfering when you join in this conversation, I am happy to hear from you.

I realized that piston balancing forces are going to be a problem with my new configuration. The piston pushing the equalized contents of the small vessel into the big vessel has to be bigger in area than the piston/check valve it's pushing against, or use higher pressure than the tank pressure. It leads to a round robin sort of system that Rube Goldberg would appreciate.

I'm not saying it's wrong, because the work needed is small enough to make an obvious gain according to my limited ability to pretend I'm doing engineering math. The air in the piston could do the work, but the air won't go into the piston because it won't move. It is not to be abandoned, however, because more work can be done by the amount of air being compressed, than is being done to get it into the tank.

Force is the problem, not work.

Therefore I have switched over to a separate process for energizing the equalized air masses in the small tank to get them into the main tank. By "separate" I mean not involving the tank or its limitations. Using electric resistance heaters, the temperature of the small equalized air mass can be doubled, and its pressure also doubled, with no moving parts. Then a big valve will open quickly, the entire contents of the equalizer will enter the big tank en masse, and the equalizer can be easily re-filled in its wake by the supercharger.

The scavenging of the equalizer can be tuned for maximum effectiveness similar to the way a pulsejet or two-cycle gas engine exhaust is tuned, by the size and shape of the tailpipe through which it exits.

This type of double-valve pump with heat added between the valves is not experimental, with water it is well-proven. It will work with check valves only. With air I think you will need a large discharge valve that can be controlled to open and close at the right time, so this will have to be variable from controls outside the tank because it probably won't work the first time. And as you say, the capable are not going to help me for free so trial and error is the way to go. But first I have to try to figure out enough about electric resistance heating to see what it will take.

Luther

The ONLY positive aspect is that you learn ! Better later than never, the more you will learn the more you will understand why it does not work.

By the way what you try to do with an electric heater is done in combustion engines by burning the fuel, but a lot quicker since the heat is generated in the mass and not transferred via a convective surface.

I maintain my wish : Good luck

If you release a compressed spring, it will overextend its equilibrium point by a typically small amount, but not by much, and it will quickly damp out, unless there is a substantial weight attached. The air compression is indeed A BAD ANALOGY, for lack of inertia. Thanks a heap for voting that observation OT, though on the plus side it establishes firmly that you don't know what you're talking about. Reply 1 on this thread pretty much nailed it.

If I knew what I was talking about, then I wouldn't have come to this forum for the opinions of others. That doesn't stop me from defending my idea as long as it makes sense to me. I can't stop you from flaming my posts but I can just keep trying to change the subject, back to the topic, and make requests for practical illustrations, examples, clarifications and logical arguments. What makes hostility, sarcasm, and insulting language a response to a technical topic? How can I guess the wisdom behind a sneering remark, if there is any? Your initial assault set the tone for an aggressive defense on my part, don't you think?

I have corrected my thinking and gone back to a simpler concept. Equalization is equalization. The heat of compression contributes to the higher, equalized pressure in the smaller vessel. Pressure doesn't go over the equilibrium point. My pendulum analogy was bad because the resistance to the pendulum's motion doesn't increase.

I am correct that there is a period of unbalanced thermal effects, with a temperature rise in the target vessel and temperature loss in the source vessel, before equalization is really complete. This is part of the equation but no longer my main point. My main point is now retracted to a more basic idea.

If you equalize the two vessels, the smaller of which is inside the larger, then the pressure is the same in both and no external work has been done. That's why the first law of thermodynamics is on my side: no thermal energy has left the tank as a result of the equalization.

Now to push all the air from the smaller into the larger vessel with a piston requires a small fraction of the work that would have been necessary to compress by conventional means the volume of atmosphere that was compressed instead, almost to tank pressure, by equalization with the tank. The addition of this much atmosphere increases the energy available from the tank because of the internal energy or heat content of the atmosphere, which adds to the pool of thermal energy that was already in the tank.

The math is very simple and thanks again to everyone who has helped me by playing the devil's advocate.

Luther

I'm sorry, but I don't believe that, either.

OK. Build one and see if it works.

Here is my latest idea on the equalization engine.

A pipe runs through the center of a tank that is pre-filled to 90 psi. A compressor pumps the pipe up to only 2 psi. A check valve keeps the air from going out backwards.

A valve in the pipe can open or close to communication with tank pressure.

There is a piston in the downstream end of the pipe constituting a pressure booster. It is single acting, and is not inside the tank. The device that operates it is not inside the tank.

When the pipe reaches 2 psi, the valve opens and the pressure equalizes with tank pressure. So inside the pipe, the pressure is 2 psi on the upstream side of the check valve and about 88 psi on the downstream side of the check valve.

The valve remains open and the piston pushes the air into the tank, from 88 to 90 psi. When the piston reaches the check valve, the valve in the pipe closes and the piston retracts. Fresh air enters the equalizer through the check valve.

Each of two external compressors develops 2 psi and the tank produces 86 psi by equalization. If someone can find fault with the idea, great, please pass on some real information that I can use. What, specifically, in terms I can look up in an engineering book, is wrong with this idea? Thanks in advance for any constructive criticism.

Drawing and spreadsheet are at http://www.cannedthunder.blogspot.com.

Luther

Look at the devices called "pressure intensifiers" and you will see how it works and that nothing new under the sun. There are production presses build in a similar way with a differential piston which becomes active when a pressure has been reached, a valve closes the low pressure supply to the cylinder and the piston amplifies the pressure in the working space.

You are very creative try to find a new idea to polarize on.

Good luck.

Thanks for the tip. I will look into pressure intensifiers. I don't think it's bad news that my process is being done already, as I'm not looking for something to patent. I think it's good news, in case maybe there will be confirmation for some part of what I want to do so I can proceed with my plans for a new kind of air compressor that uses existing pressure to take a load off what conventional compressors have to do.

Luther

Correction regarding compressing air by pressure equalization

I have discovered a mistake in the way I was using the air compressor equation.

Compressors do three jobs.

1. Intake is negative work because the piston is already moving under power from the crankshaft and the intake pressure, whether atmospheric air or something else, enters on its own power and cancels the work done to move the piston on that stroke.

2. Compression is when the air trapped in the cylinder is being reduced in volume and increased in pressure.

3. Delivery is when the air has reached tank pressure and is being delivered to the tank at constant pressure.

Each of these three steps has its own calculation to find out the work in ft-lbs or whatever units you use. They can be combined into a single equation so the work of a standard compressor can be found quickly. That's where I got it wrong. The combined equation is for standard compressors and this equalizing compressor is not standard. A closer look was needed, as prompted by some emails and forum messages, thanks to all for your input.

The calculation has to be done separately for each of the three steps with attention paid to what the calculation is trying to do. My mistake was to assume that the equalized pressure was the intake pressure on an intake stroke. It is not. The piston is not moving when the tank air enters, it has already had its negative work intake stroke done by atmosphere. The extra pressure then becomes an extra load that has to be pumped laboriously back into the tank. The good news might be that it doesn't actually have to go into the tank. So forget that load and just use the air? The problem is still that a lot of tank air is used to compress a little atmosphere. So more creative work is needed. Unfortunately pressure is not energy, and when you put it someplace to do something it has to be gotten back out of the way at a cost. That seems to be the problem with shifting pressure around within the system, even if it is free of external work to compress air with air within the tank. I believe there is a solution.

The idea can be re-thought-out since compression by equalization is free of external work and since any atmosphere brought into the system contains external energy.

Luther