A STIRLING profitable to himself?

[dedeleco]

Please understand well the Carnot cycles, in particular in stages, which allow maximum cooling, with liquid nitrogen, then with liquid helium 4 (4,2 ° K); then that of liquid helium 3 (0,3 ° K), until the ultimate (demagnetization) mK and microkelvins 0 ° K much better than microdegrè, all powered by 2 cold and hot sources, which provide the necessary hidden work, by PV expansion, often with an EDF electric alternator, very practical but not essential !!.

The mechanical work remains mechanical without going through an electrical conversion, as in the storage fridge sold with a hot source heated by gas or fuel, with the mechanical work not visible, but very real, in the gases of the tubes !!

This remark does not explain the amplification of the deltaT.
Amplification of the delta T WITHOUT EXPENDITURE OF MECHANICAL ENERGY
Basically, there is no difference with what the Maxwell demon does: separate the hot from the cold.

there is real PV work by expansion and compression of gases and controlled thermal contact, very real mechanical energy, as much as in a Stirling engine and a detailed analysis will show that the efficiency far from 100% for each stage, by multiplication effect, requires a very high calorific energy in the first stage for a small final energy at the final stage of large delta T, as well to cool as heat !!

It is totally different from the Maxwell demon who, like a demon, works without an energy source, as long as there is only one heat source at the start to create two heat sources !!

If it has 2 sources at different T it is no longer a demon, but a very real thermodynamic system !!

Read with great care :
http://fr.wikipedia.org/wiki/D%C3%A9mon_de_Maxwell
also in english:
http://en.wikipedia.org/wiki/Maxwell%27s_demon


Watch this!
http://en.wikipedia.org/wiki/Pulse_tube_refrigerator
it is enough to realize the compressor by expansion and retraction of gas passing alternately from hot to cold to realize this refrigeration with a collection of stages !!

Montherme offers only one possible version of this, and the big difficulty is to have thermal switches without losses between hot and cold (very close to the Stirling engine).

[Capt_Maloche]

Nice description of Maxwell's demon

Just what are you guys doing here?

[teatime]

there is real PV work by expansion and compression of gases and controlled thermal contact, very real mechanical energy, as much as in a Stirling engine .

Hello dedeleco,
Yes dedeleco, we can imagine that there is indeed mechanical energy that is at play in the thermodynamic cycle described by the “monothermal” team. But this mechanical energy is not brought to the system in the form of mechanical energy (if we neglect the mechanical energy provided by the displacement piston, because it is small and only a function of friction and pressure drops) .

We have a hot source and a cold source and we obtain a temperature higher than that of the hot source and a temperature lower than that of the cold source.
It is true that there would be nothing extraordinary if one expended a lot of thermal energy to achieve this result. But the thermal energy losses are only those which are inevitable in any real device (conduction, convection, radiation, viscosity, vibrations, leaks): they are not those of the thermodynamic cycle itself !!! ...

If the people at "monothermal" think they have a Maxwell demon, it is because said demon had the (imaginary) faculty of separating hot from cold.
What is going on in their heat pump?
We have a hot spring and we have the ambient which acts as a cold source. The gaseous fluid circulates from one side to the other etc ... and the heat exchanges produce a deltaP (a pressure variation) which induces a secondary deltaT (a temperature variation) on the hot side and on the cold side. We have the appearance of a deltaT on the hot side and we have the appearance of a deltaT on the cold side. In other words, we separated the hot from the cold on the hot side and we separated the hot from the cold on the cold side: we have the equivalent of two Maxwell's demons, one demon on the hot side and another on the cold side. .
These two demons are not able to separate the molecules one by one to make them appear hot and cold from the lukewarm. As such, they are not real Maxwell demons. But whatever ! The important thing is that the result achieved is the same: separate hot from cold.
So there would be something very interesting in this heat pump (and that's an understatement) since there would be a decrease in entropy (which thermodynamics says is impossible).

Montherme offers only one possible version of this, and the big difficulty is to have thermal switches without losses between hot and cold (very close to the Stirling engine).

This is incorrect. The pulse tube refrigerator is a device that does not produce secondary deltaTs on the hot and cold sides. The principle of operation is very different. Where do we have a temperature higher than that of the hot source? The "monothermal" device is made up of TWO heat pumps, one on the hot side and the other on the cold side.


Hello Capt_Maloche
I suggested creating a dedicated thread. But I don't know if this discussion will continue.
?

[dedeleco]

It is about the deep assimilation of the principles of thermodynamics, which considering its generality, is not easy !!
It takes the same rigor as in mathematics!:!
We even see pros or pretended such, as picolino, in an engine manufacturer, making basic errors like asserting that the T of the cold source of an engine is the T of the fuel mixture entering the engine !!
type on pantone wikipedia to see this serious irremovable error !!

(conduction, convection, radiation, viscosity, vibrations, leaks): they are not those of the thermodynamic cycle itself !!! ...

if, there are thermodynamic cycles with poor intrinsic efficiency and perfect cycles are inaccessible because, idealized with quality incompatible with each other, they must be reversible, therefore very slow, which is incompatible with the adiabatic cycle portions, completely thermally isolated, (slow equalizes the T !!) with also this same isolated gas which must be in perfect thermal contact in the other parts of the cycle, at fixed T, in perfect thermal contact with external T sources !!

As in mathematics, the word demon of Maxwell has a precise definition, not respected or not assimilated by people often, for lack of rigor, too tiring !!

since there would be a decrease in entropy (which thermodynamics says is impossible).

forget the precise rigor of this principle: only for an isolated system which is not the case with 2 isolated sources, a small part of the system sees its entropy decrease its entropy while the rest sees its entropy grow strongly !!

Visible by decompressing a gas which makes the cold very strongly (method to liquefy the air) in the opposite direction to the heat given off by compressing this gas, clearly visible with a bicycle pump inflating with ardor a tire, to the point of burning hands !!

The pulse tube refrigerator is a device that does not produce secondary deltaT on the hot side and the cold side

If, if we put several stages, like the monotherm, with the work (pseudo Stirling engine) of a part of the gas given to another part of the gas (pseudo Stirling in heat pump) we will obtain the same with any system giving differences of T, gas, pulse tube, or even magnetic, as used at very low temperature by demagnetization !!

So the monotherm is nothing extraordinary, in principle, the whole problem is to achieve it with sufficient efficiency, which is difficult, because the different motor and heat pump functions are not independent and freely optimizable, this which allows to have a lot of floors in self-multiplying form (at least on paper), but which in reality, imperfect, will come up against the multiplication of losses and therefore ask for a very difficult optimization .;

It is clear that the monotherm was not carried out even in demonstration and they do not give a quantitative, serious thermal analysis of the thermal fluxes, even ideal, to see appear the first difficulties, with their internal sources, cold and hot to limited capacities not calculated. !!

So the limitations will be the same as the stage systems for cooling, liquefying gases, such as air and helium, or for stage heat pumps !!
There will be a multiplication of inefficiencies !!


They are aware of this with:

with a counter-current heat exchanger of efficiency greater than 95%, the heat flow from the hot source to the cold source would be less than five percent. With such a small heat flow it would make sense to use a heat pump in an attempt to take advantage of the benefits of an internal cold source. The total energy expenditure required to keep the temperature of the internal cold source low would depend on the efficiency of the countercurrent heat exchanger, the efficiency of the heat pump and other minor losses.

and a yield of 95% is very very difficult to achieve even for a single stage !!

[Capt_Maloche]

...
Hello Capt_Maloche
I suggested creating a dedicated thread. But I don't know if this discussion will continue. ???

Why not?

Start by replicating simple models like these, and then try to improve the model


http://www.youtube.com/watch?v=G2CCDwwRfhw

Besides between us, don't you think that one could easily operate a stirling with the exhaust gases of a car? we talk about energy in KW

[dedeleco]

we could easily operate a stirling with the exhaust fumes of a car? we talk about energy in KW

certainly, but effective Stirlings are expensive (helium under pressure at much better efficiency).

Peltier modules are a less complex, inexpensive low power solution used on the internet for trucks and commercial.

Otherwise a thermoacoustic generator is another possibility without mechanics like pistons and seals, but with other difficulties solved industrially for advanced uses.

[teatime]

Hello,

"Montherme" offers only one possible version of this.

Inaccurate.

If I judge by the last message from dedeleco, it would seem that I am unable to express myself clearly (he damn clearly didn't understand the good boy). So, I resume by trying to be more clear. I will have to detail.

Whether it is a Rankine cycle (cycle with change of state, for example with water / steam), a Brayton cycle (for example aircraft jet engines), a cycle of Stirling, a Diesel cycle or another cycle, it is necessary to clearly distinguish two things: the theoretical thermodynamic efficiency and the real efficiency. The difference between these two is the losses that affect any real device. These losses are for example the energy dissipated by vibrations (audible or not), the thermal energy dissipated by conduction, convection, radiation, the mechanical energy dissipated by friction, leaks, etc. The theoretical efficiency cannot be achieved in reality.

We have given examples of motor cycles where thermal energy is transformed (partially) into mechanical energy or work. Some of these cycles can work in reverse: we provide work that we transform into thermal energy (cf. heat pumps: we separate hot from cold with the expense of mechanical energy). So generally, either we transform thermal energy into work or we transform work into thermal energy.

The invention (the heat pump) which is explained on the site “monotherme.com” does not aim to convert thermal energy into work since there is not even a motor piston to recover work. And, moreover, said invention does not aim either to convert mechanical energy into thermal energy since there is not even a motor piston to give this mechanical energy to the system. There is no mechanical energy exchanged with the system, neither in one direction nor the other. The invention of “monothermal” is situated in this scenario where only thermal energy is used and in order to restore thermal energy in another form.

This will make us think, for example, of gas fridges, especially used for camping. Thermal energy is provided in the form of a small flame (gas combustion) and this energy feeds a thermodynamic cycle which makes it possible to make cold. This thermodynamic cycle requires thermal energy to be consumed. In other words, it is the thermodynamic cycle ITSELF, THEORETICALLY, which requires that thermal energy be expended: losses in the real world are then added.

However, in steady state, the THERMODYNAMIC CYCLE used in the heat pump from "monothermal" would NOT REQUIRE THERMAL ENERGY EXPENDITURE! ... Indeed, it would be only the inevitable losses in the real world which would represent the TOTALITY. of thermal energy expenditure. This is how the heat pump from "monotherm" would be unique, incredible, extraordinary.

Is this an error, an illusion, a confusion, a misunderstanding, a manifestation of our ignorance? This is most certainly what scientists and engineers with some notions of thermodynamics will immediately think (second principle, entropy, etc.).
And yet, it turns, as Galileo would say. This is what they state in "monothermal" and I think they are right, even though I am well informed of the reasons why one should think they are wrong.

Indeed, there is a regenerator whose theoretical yield is assumed to be equal to one and which is crossed in one direction then in the other by a gaseous fluid which is therefore heated then cooled then heated etc. It is like a swing ideal where the potential energy is transformed into kinetic energy then the kinetic energy is transformed into potential energy etc ... endless. Here it is hot then cold then hot, cold, etc ... indefinitely.

Since the regenerator has an ideal yield equal to one, there is no thermal energy that migrates from the hot side to the cold side. The gaseous fluid alternately passes from one side to the other without THEORETICAL loss of thermal energy.

Since the gaseous fluid is heated, cooled, heated etc ... at constant total volume, we have pressure variations. These pressure variations affect all of the molecules of the gaseous fluid (equally).

The whole question is there: if these pressure variations do not require that heat migrate by the regenerator from the hot side to the cold side (from a THEORETICAL point of view) then, in monothermal conditions, they are right to think that they discovered a demon of Maxwell (there will be no more doubt and I will explain the reasons). This is the question that will determine the outcome of this whole affair AND NOTHING ELSE. We must therefore try to answer them.
And then, even though it was not a Maxwell demon, it is a whole new process that is capable of doing amazing things: there is no such thing among the whole of all known processes for heat pump.
The rest will be for later, perhaps (and on a wire dedicated to this heat pump).
teatime
right here: http://monotherme.com/index.php?c=monotherme

[dedeleco]

However, in established regime, the THERMODYNAMIC CYCLE used in the heat pump from "monotherm" would NOT REQUIRE THERMAL ENERGY EXPENDITURE! ..

is not written and even less demonstrated by calculating heat flows and even idealized work with perfect exchanger.

As with commercial gas refrigerators, there is internal mechanical work reused to activate the heat pump!
If I get tired of calculating the thermal, mechanical, idealized flows (monotherm does not, tiring), I am sure that I will find respect for the Carnot principle and therefore spending thermal energy to do work with 2 sources used to decrease or increase the temperature, as for the gas fridge.

One point is not clear and precise these are the gas flow and pressure equalization properties in the regenerator !!

It is crucial and essential
If it is easy to flow, the pressure is uniform and the gas on one side will never be compressed relative to the other, making the monotherm impossible.
If the flow is difficult with unequal pressures, the piston called displacer, will undergo a significant force and will have to carry out a work to be taken into account and not negligible, which intervenes in the assessment and this piston is therefore also motor !!

In addition, the finite speed to be respected prevents an idealized analysis, since the yield will depend on the speed and the forces on the piston called the displacer but in reality also the motor !!

Its work of piston engine will make respect the principle of Carnot !!

[teatime]

If easy flow, the pressure is uniform and the gas on one side will never be compressed relative to the other making the monotherm impossible

This statement shows to those who follow that you did not take the trouble to correctly identify what we are talking about.
How could the answer to a question that has not been understood make sense?

For my part I think I understood the proposed device. I am even sure after taking the time to fully understand.

It was about understanding this:
when the piston moves slowly then we have "an easy flow" ... and in such a case, in fact, there is no pressure difference between the two compartments ... but this is precisely how their machine works !!! ...

Their machine works very well WITHOUT pressure difference between the two compartments.

You have not yet understood the principle of operation of their machine.

When the gaseous fluid is heated through the regenerator, there is a reversible adiabatic compression of ALL the molecules (those of BOTH compartments) which is induced, at constant total volume, by successive and local reversible isobaric transformations (in the regenerator, groups of molecules follow one another). A temperature higher than that of the hot spring is then reached on the hot side of the machine. The pressure is assumed to be the same for all molecules and wherever they are (whether in one compartment or the other or in the regenerator).

When the gaseous fluid is cooled by passing through the regenerator, there is a reversible adiabatic expansion of ALL the molecules (those of BOTH compartments) which is induced, at constant total volume, by successive and local reversible isobaric transformations (in the regenerator, molecules come and go). A temperature lower than that of the cold source is reached on the cold side of the machine. The pressure is assumed to be the same for all molecules and wherever they are (whether in one compartment or the other or in the regenerator).

Before making a heat balance, we will start by trying to make sure that we have understood what is at stake.

Then, we agree that this is a process that has never been used (to our knowledge) as a heat pump. This novelty will attract our attention since we do not know, at this stage of our discovery, what could be its interest and its possible field of application ...

On the basis of this interest which cannot fail to exist for scientific minds, curious, lovers of reflection, of culture, a more in-depth study will be well motivated.

And it is ONLY then that things get really interesting.

We then understand that there is no expenditure of mechanical energy in the sense that said expenditure is very small AND that it is not dependent on the exploitation OR NOT of the potential thermal energy appearing under the form of a temperature higher than that of the hot source or lower than that of the cold source ...

Then we understand that if the molecules do not mix when entering a compartment then they come out exactly at the temperature at which they entered it ...
When a compartment is full then all groups of molecules are at different temperatures (but, of course, at the same pressure).
If we then allow the groups of molecules to mix, we obtain an average temperature and we have an increase in entropy.

And that's when something amazing happens:
while the compartment is emptying (and it is on the hot OR cold side),
there is a variation of the pressure in all the system (for all the molecules) so that the molecules will leave at a variable temperature (increasing for the cold side and decreasing for the hot side). A secondary deltaT has appeared.

What about entropy during THIS phase?
Entropy decreased during this phase.
This assertion does not suffer any possible dispute.

But the gas then enters the regenerator and the secondary deltaT is destroyed by the thermal inertia of the regenerator.

But the secondary Delta can be exploited just before its inevitable disappearance.

Without spending mechanical energy ... the thermal energy spent seems to be the same as in the case where the groups of molecules do not mix when entering AND when leaving the compartments, in comparison with the case where they mix and where a secondary deltaT appears on the hot side AND the cold side.

The device is incredibly simple and surprising.

In the absence of a rigorous and in-depth study, we cannot rule out the possibility that this invention is a threat (or an opportunity) for the refrigeration industry (among others).

It is only on the basis of a good understanding of the above process that we will rethink (from a new angle) the Stirling engine.
Indeed, by adding a driving piston approximately 90 ° from the displacing piston, we have a Stirling engine. But it would then be a question of dimensioning it so as not to destroy the effect of the heat pump (the appearance of a temperature higher than that of the hot source and lower than that of the cold source). This seems important since it is these two maximum and minimum temperatures which give the maximum pressure variation. However, the greater this variation in pressure, the more power the engine has ... to compensate for the loss of power that would be obtained at a lower speed. This is what we learn on their website.

teatime

[chatelot16]

Besides between us, don't you think that one could easily operate a stirling with the exhaust gases of a car? we talk about energy in KW

of course we can do it!

an average internal combustion engine sends about 1/3 of the power consumed by the exhaust ... the usable temperature is not huge, we could hope for 5% efficiency

0.33 * 0.05 = 0,0165 or 1.65% yield to gain

and this system would be quite bulky and heavy: no interest in a vehicle ... much more interesting in a cogeneration thermal power plant

and it's not just the exhaust, it's also the engine block cooling heat

and for the average temperature the stirling is not the best: the good old steam engine gives a performance much closer to the theoretical maximum ... and it is already done commonly on the very large boat engine: steam recovery saves 5% on the total yield: we exceed 50%