Lets beat up Carnot

Discussion on Stirling or "hot air" engines (all types)
VincentG
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Re: Lets beat up Carnot

Post by VincentG »

There is a kind of segue in the Wikipedia article about the Newton-meter:

The unit is also used less commonly as a unit of work, or energy, in which case it is equivalent to the more common and standard SI unit of energy, the joule.[2] In this usage the metre term represents the distance travelled or displacement in the direction of the force, and not the perpendicular distance from a fulcrum as it does when used to express torque. This usage is generally discouraged,[3] since it can lead to confusion as to whether a given quantity expressed in newton-metres is a torque or a quantity of energy. However, since torque represents energy transferred or expended per angle of revolution, one newton-metre of torque is equivalent to one joule per radian.


This is exactly what sparked this idea. The fact is that the equation for force(newton meter) and energy(jule) is the same. So x amount of force is needed for y amount of work. If the force can't move the object, no work is done. But maybe the repeated oscillating force can be harnessed.

As mentioned in my other thread, in the real world everything is elastic, so it's impossible to exert force with zero movement. Therefore any force produces work. Using the work is another matter.
Fool
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Re: Lets beat up Carnot

Post by Fool »

Fool said: "1 Joule is 1 Newton of force used to move an object 1 meter of distance. AKA: Energy."

Thanks to Tom. It should read: 1 Joule is 1 Newton of force applied to a system/object for a distance of 1 meter. AKA: Energy.

No motion of the system is necessary. Could be nothing more than frictional sliding on a fixed object. Then the Joule becomes heat and is probably lost to the ambient and cosmic background, where all temperatures are the same. Entropy you know.

Since I'm using SI (System International), AKA, mks system, or the meters, kilograms, seconds system:

A Newton is equivalent to kilograms multiplied by meters divided by seconds squared
Or
N=kg•m/sec^2

This is derived from Force=Mass times Acceleration
Or
F=M•A

So a Joule is:
Joule = N•m = kg•m^2/sec^2 = kg•m•A

This means that Acceleration 'A' is:

A=m/sec^2=Joules/(kg•m)
Joules divided by the product of mass times distance.

In other words: A Joule applied to a mass for a distance, will produce an acceleration that depends inversely on both, the bodies mass and the distance applied. And of course friction.

Remember physics is mathematics. Since physics is also science, mathematics is also science. Without the mathematics, there would be no physics. Also, it is not enough to know the mathematics/physics we must also know when and how to use the mathematics. (Okay, we didn't need those comments. LOL )

Goofy, sorry for the fool I am. I like BR Best Regards. Makes more sense. I thought it was your initials. LOLOOR (Out Of Respect) ( I made that up.) Your posts are Excellent. Thanks.

Tom the following may help:
Work is applied energy. Kinetic energy is internal energy. Not all applied energy becomes internal energy. A change to the internals must happen. Velocity, height, temperature, spring deflection, etc. are examples of internal energy. Heat, Light, and Work are examples of applied energy. Force is one way to apply energy.

Sometimes we use a past or future tense for applied energy, such as the current temperature is 300 degrees, so 300 degrees of energy has been applied, we will apply 300 more for a total of 600. This does get very confusing, often.
It took me a long time to produce the calculations for that first post, of course a lot of it was procrastination. That helped a little in allowing me to rethink what I was preparing. I was actually surprised at the answers I got. I hope that few errors were made. I hope to work through them as found. We will see.
Fool
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Re: Lets beat up Carnot

Post by Fool »

VincentG, everything being elastic leads to my thoughts on hysteresis. If you put a bungee on a large ship, and pull with one Newton for a distance of one meter, then stop and relax, one Joule of energy will have been wasted as heat, flexing the bungee, and moving the ship zero. Hysteresis, also called slop, backlash, or flex, is usually detrimental and produces heat or internal temperature rise. Right?
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

Fool wrote: Fri Mar 15, 2024 6:08 am Fool said: "1 Joule is 1 Newton of force used to move an object 1 meter of distance. AKA: Energy."

Thanks to Tom. It should read: 1 Joule is 1 Newton of force applied to a system/object for a distance of 1 meter. AKA: Energy.

No motion of the system is necessary. ...
I'm really not sure about this. First, is it not self contradictory?

"...for a distance of 1 meter..." and "...no motion necessary..." ???

As far as I know there is no energy being generated by the tank full of compressed air sitting in my workshop though there are molecules of air constantly colliding with the inner wall creating a great deal of pressure at about 150 psig

There is a pressure differential between the inner and outer wall of the tank, but no heat is continually being generated...

Though, it is true, heat was continually being lost from the tank immediately after the air was compressed into it, for some time afterward.

Does this "prove" there is some inherent difference between the gas "pressure" in the tank and the kinetic energy of the gas molecules colliding with the walls? Or how can this be explained?

Not trying to argue any point, for or against any theory really, but I do, and always have found this a bit of a head scratcher.

It is often stated that ALL the power or work used by an air compressor (electricity input or whatever) to compress the air into the tank by an air compressor is lost to the outside air as heat.

But, the air in the tank still has "pressure" and can be used to do additional work powering air tools.
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

I think, aside from the above considerations, this revised statement:


"1 Joule is 1 Newton of force applied to a system/object for a distance of 1 meter. AKA: Energy."

Is still not accurate, or not applicable in the context.

Torque and Energy are fundamentally different.

Simply applying a force for a distance does not meet the definition for Newton-meter in the context of ENERGY transfer. There has to be acceleration.

If I push an object with 1 Joule, accelerating it to 1 meter/sec. to transfer another Joule ther has to be acceleration otherwise, I'm just floating along with the object at the same speed. (Two objects floating along together in outer space, side by side at 1 meter/second)

The next Joule must accelerate the object to 2 meters/second. Otherwise there is no energy transfer taking place.

Even with VincentG's theoretical micro scale elastic energy transfer there is or I think must be some motion on a microscopic level.

What about friction?

Well, friction requires motion to produce friction.

Also, again, the mass of the "object" is relevant
Fool
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Re: Lets beat up Carnot

Post by Fool »

It all depends on how you look at it. Yes, motion of the applicator, no motion of the internal system. The system is inside the boundary. Like a car spinning it's wheels (Burning rubber.). Tires moving, not the road or car. The tires are just the applicator of the force to the ground. Motion between system and applicator. No motion of the system. System does, and receives, no work, only heat energy, Joules, as a consequence of work, heat equivalence. The Applicator, applies one Newton over a meters Distance, equivalence, Force times Distance, for every Joule.

Yes torque and energy are different, same units, different models. Torque is a rotational force. Energy is Force times Distance. Power is Energy times Time.

KE = 1/2•MV•^2 = 1/2•kg•m^2/sec^2
PE = Mgh = kg•m/sec^2 • m = kg•m^2/sec^2
Both the same units as Work N•m = kg•m^2/sec^2
Joules, Joules, Joules

Torque is different, but sort of has the same units.
Torque = m•N = m•kg•m\sec^2
We should start calling them meter Newtons.
Also foot pounds.
Not energy. Not Joules.

The pressure inside a tank is constantly kept heated by the ambient environment around it. The ambient environment is an open system. It allows solar energy to keep it at ambient, or even chemical energy in the form of fuel and oxygen, if indoors.

When air is compressed into a cylinder and left to sit, only the work energy from heat of compression escapes. What is left is the Tcold isothermal work energy of compression. The energy escaping is also seen as a loss of pressure when the air cools back down to ambient, heat rejection. The extra work/energy by adiabatic compression is lost when it cooles, and saved if isothermal compression at Tcold is used. It takes less energy to compress to the same volume if kept at Tcold. This is the same as back work, larger if adiabatic, smaller if kept at Tcold.

A good question at this point would be: If isothermal compression is so efficient, why don't all compressors use it. IMHO the answer is speed and size. An isothermal compressor would be much slower and or larger.

Isothermal compression is strived for by adding a thing called an intercooler. However, it is more an after compression cooler than an isothermal compressor. Also cooling fins on the compressor cylinders, do keep compression cooler.

This is why Stirling Engine designers strive to make the cold heat exchanger so large. Larger heat exchangers have larger dead space and resistance. A compromise is needed. Pressurization makes up for some of this dead space.

It is also why people, studying this field, have evidence proving the need for heat rejection. That evidence, and lots of mathematics to support it. Plus a plethora of of engines, and heat pumps, that seem to need it.
matt brown
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Re: Lets beat up Carnot

Post by matt brown »

Tom Booth wrote: Fri Mar 15, 2024 7:59 am
As far as I know there is no energy being generated by the tank full of compressed air sitting in my workshop though there are molecules of air constantly colliding with the inner wall creating a great deal of pressure at about 150 psig

There is a pressure differential between the inner and outer wall of the tank, but no heat is continually being generated...

Though, it is true, heat was continually being lost from the tank immediately after the air was compressed into it, for some time afterward.

Does this "prove" there is some inherent difference between the gas "pressure" in the tank and the kinetic energy of the gas molecules colliding with the walls? Or how can this be explained?

Not trying to argue any point, for or against any theory really, but I do, and always have found this a bit of a head scratcher.

It is often stated that ALL the power or work used by an air compressor (electricity input or whatever) to compress the air into the tank by an air compressor is lost to the outside air as heat.

But, the air in the tank still has "pressure" and can be used to do additional work powering air tools.
Each mole of gas has the same internal energy when the same temperature despite the volume occupied by each mole (ie density). Therefore, your air compressor has the same internal energy per mole inside tank as ambient when tank T equals ambient T, but the textbook response would result in something like this...

isothermal.png
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However, this does beg the question...how can a low pressure volume have more "internal energy" than a high pressure volume ?
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

It seems that materials react physically before, or more quickly than they react thermally.

For example, if you stretch a rubber band it gets hot and if held in a stretched out position long enough will gradually cool back down to ambient temperature.

Now let it go and it snaps back instantly.

But it will now be cold.

Gradually it will warm back up to ambient temperature

https://youtu.be/1NS55QTb0H8?si=CxJtBalsKSSN4od2

Same thing with air. It is "elastic" or has similar elastic properties.

So as the air leaves the tank where it was held in a compressed state, it "expands" like a spring that was compressed and then it is cold.

Gradually it will absorb heat and warm back up to ambient, but there is a delay or lag between expansion and heat absorption.

The expansion is nearly instantaneous, but the heat absorption, or reabsorption takes time.

This is also why adiabatic expansion can be used to liquefy gasses.

The compressed gas, when released expands and cools using its own internal energy resources.

When there is no heat found to be available the expanded cold gas condenses into a liquid state.

You can get the energy from the compressed air as it expands. It makes up the difference later.

Likewise, compressing a gas makes it hot. It won't loose that additional internal energy immediately, so will try to re-expand if possible immediately. Only if it can not spring back, or is not allowed to spring back will it gradually dissipate the "heat of compression".

So a flywheel can drive a piston to TDC without isothermal heat loss during compression. The "heat"/energy is retained and the working fluid "springs" back.

With adiabatic expansion the gas expands and does work just like the air from a tank of compressed air, or a rubber band or a spring. then it goes "uh-oh, I've lost too much energy", and contracts.

The physical reaction or "work" happens first. The thermal response lags behind.

https://youtu.be/2hYQtB4QkEY?si=-hq4LJUZ3t6sWCm2
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

In the above video, at the end of the last post, what is happening?

The gas is not expanding by absorbing heat. It is expanding at the expense of its own internal energy, causing it to become extremely cold.

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Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

As I've tried to point out before. The Carnot Limit makes perfect sense and I can more or less agree with it if a definition of "heat" is adhered to consistently.

First "heat" is viewed as the joules supplied to (transfered to) the engine.

Then "heat" is calculated by the Carnot equation on the absolute scale, viewing "heat" as all the molecular motion of the working fluid down to absolute zero. (Not just the "heat" added or actual Joules transfered)

The Carnot formula accurately calculates the percentage of heat "available" or actually supplied.

Say 2000 joules are supplied (to raise the temperature of the hot side above ambient)

If the "Carnot efficiency" is 20% all that means is that the 2000 joules are 20% of "all the 'heat'" or all the molecular motion/energy of the working fluid down to absolute zero including the heat added along with the heat that was ALREADY THERE!

This harmonizes perfectly with the first law, conservation of energy

But when you turn around and take the 20% result and apply that to the 2000 "available" or supplied joules and try to say that only 20% of that 20% are convertible to work, then I have to protest.

That is not logical. It has no basis. You're deducting 80% of the "heat" on the absolute scale, then deducting 80% of the actual remaining heat above ambient that were actually supplied!

Where did 80% of the supplied heat go?!?!?!

To the mythical "cold reservoir"?

OK let's measure that. Measure the heat at the cold heat exchanger. Get some instruments, infrared camera, thermocouples, the works.

The "rejected" waste heat isn't there!

Where did it go?

The "available" heat that was available to convert into mechanical "work" was converted to mechanical work. That is not any violation of the conservation of energy.

The way the Carnot Limit is being interpreted and applied is a violation. 80% of the heat supplied is vanishing into thin air!

People think Tom Booth is just a careless, incompetent "scientist" who doesn't know how to do a valid experiment.

OK, well, do your own experiment

It's too hard! Experiments are really really difficult. Blah blah blah.
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

If you ask me, the only reason academia (or whomever) came up with this bogus, transparently ludicrous application of the so-called "Carnot efficiency Limit" formula is they could not admit any possibility of any kind of "perpetual motion" whatsoever, or even anything that looked like perpetual motion, such as an "ambient heat engine", though such things must be possible, as they DO clearly exist in actuality:

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VincentG
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Re: Lets beat up Carnot

Post by VincentG »

Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

That's all very interesting, but still, getting energy from a drinking bird toy seems like it could never be more than extremely low power and impractical how to scale it up?

Giant drinking birds on the seashore?

What I will be testing soon, I think, is a "rice" engine with methylene chloride or some similar refrigerant that will boil at ambient temperature as a working fluid. (Possibly just plain water in a vacuum as a saturated vapor).

Keep the top of the engine slightly cooler than ambient.

Numerous sources claim that the "hand boilers" do not actually boil.

https://youtu.be/eRj-9TcFkr8?si=iLXvFcnU24mRkKiA

Well, that may be, but clearly IMO the fluid is evaporating and expanding to create the effect. So what exactly is supposed to be the distinction between "boiling" and evaporation?

In the above video, he does not create a saturated vapor. The upper bottle is still full of air, so his DIY version doesn't work very well, but the ease of construction he demonstrates is why I chose that video as an example.

That is the idea of the inverted mason jar on top of the "rice" engines in my recent video:
ambient-heat-rice-engine.jpg
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https://youtu.be/bw7izz9fUT8?si=TuVqTjJCpBIGnmi6
Tom Booth
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Re: Lets beat up Carnot

Post by Tom Booth »

Also earlier on in the "rice engine" thread I posted these suggestions::
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Tesla's idea, or goal, or reasoning was, if the supplied heat is converted to mechanical output so as to NOT be "rejected" to the "cold hole" or whatever constitutes a "sink' then it would be possible to have a "self-acting engine". Contrary to the conclusions of Carnot and Kelvin who insisted in their writings at the time that ALL the heat supplied was only "transported" by the working fluid "through" the engine, from the hot to the cold "reservoir'.

I'm not sure why such a simple common sense idea drives so many science types to absolute hysterics.
Fool
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Re: Lets beat up Carnot

Post by Fool »

Tom Booth wrote:It seems that materials react physically before, or more quickly than they react thermally.
This clearly isn't the case for heat transfer from a xenon flash, which can incinerate paint from a surface almost instantaneously. Temperature difference drives heat. The bigger the difference, the faster the energy flows. Cross sectional area, sometimes called surface area, and length of heat path, are also factors.

A good analogy is a cars fuel tank. Pull into a station, there is a delay before fuel starts pouring into the tank. Going in to pay. Talking to the cashier. Getting your card out. Putting the hose into the tank. Even then the size of the hose and pump limits how fast the tank fills, 10-15 minutes, or so for 15 gallons.

Pit stop a race car, minimal delay, fast acting filling, 15 gallons in under 10 seconds. Wow!

Heats the same way, except there isn't any delay. Instantaneously, as soon as there is a temperature difference, heat energy begins to flow. So regardless how short a time, some heat will flow. How much depends on the path, and material. Short, wide, and conductive, leads to high speed heat flow. You guest it. Long, narrow, and resistive, slow heat flow.

A rubber band has a high heat capacity, and is fairly resistant to heat flow, and small surface area. Air is fairly resistant as well. Heat transfer will be slow, like a small hose, however no delay. Heat transfer begins before the band is fully stretched, just as soon as there is a temperature difference. Granted, not much, but some.
Tom Booth wrote:The "rejected" waste heat isn't there!

Where did it go?
Your experiment shows a small but significant heat rejection. Sufficient enough not to ignore. What we are now discussing is how much heat actually entered the engine, and how much work was produced. I say, zero for zero efficiency. It could be slightly more than that, but very slightly.
Tom Booth wrote:OK, well, do your own experiment

It's too hard! Experiments are really really difficult. Blah blah blah.
That is uncalled for. I point out how easy it is to do poor science, Pons and Fleischmann, not to discourage experimentation, but to encourage good practices.

To improve one of your experiments, you would want to put a thermal couple, or RTD, on the inside and outside of both the hot and cold plates. It seems ridiculous, but the degree or so would tell us a lot about how much energy is actually flowing through the heat exchangers. The measuring devices should also be field calibrated using an ice bath and boiling water before, and after the experiment. No salt.

Also mathematical number crunching, theory, needs to accompany any reported data.

It is not enough to say Captain Hook ate oranges on the voyage and didn't get scurvy. That is just statistics. Science dictates, finding the chemical, ascorbic acid, and how the human metabolism utilizes it, before any conclusions can be made. And that is just the beginnings of that science.

Please, carry on. Be meticulous. Be careful. Good work, so far. Encourage. Encourage .Thanks.
Tom Booth wrote:If you ask me, the only reason academia (or whomever) came up with this bogus, transparently ludicrous application of the so-called "Carnot efficiency Limit" formula is they could not admit any possibility of any kind of "perpetual motion" whatsoever, or even anything that looked like perpetual motion, such as an "ambient heat engine", though such things must be possible, as they DO clearly exist in actuality:
Actually it is the other way around. Lack of discovering any "real" perpetual motion, over unity, devices has lead to the discovery of the Carnot Theorem and Entropy. This has not stopped the search for free energy over unity machines. Even I continue the search. It is easier to think up some contraption that "should" work, but doesn't, than to understand and demonstrate why it doesn't. Don't let others sway you from discovering and demonstrating, why they don't work. It is fun to do, and it gets easier with more practice.

The drinking bird, and the barometric clocks both have an unusual form of input energy, both tied to the sun. Solar heat.

Without solar heat the bird would freeze up. Without solar heat the barometric fluctuations would cease.

Earth is not an isolated system, neither is the drinking bird. Put it in a sealed jar and see if it keeps going.

There are other machines working long term, and briefly, on other energy sources. It's your job, should you choose to accept it, to figure out what those sources are. Usually it's well hidden batteries, or blowing air on the device. Scams run rampant in these areas.
Tom Booth wrote:I'm not sure why such a simple common sense idea drives so many science types to absolute hysterics.
I would call it on the side of science, dismissal.

I would call it on the side of others, cognitive denial and choosing to be ignorant.

It's much easier to be ignorant than to well educate one's self. Look at how many years we've been studying this, and we still know nothing. Socrates.
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