Thermoacoustic, how?

Tips, advice and tips to lower your consumption, processes or inventions as unconventional engines: the Stirling engine, for example. Patents improving combustion: water injection plasma treatment, ionization of the fuel or oxidizer.
dedeleco
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by dedeleco » 04/01/12, 02:56

give us some ideas on the conversion of sound into energy: I still do not see anything precise

I put in the past scientific links, this time this one with a course of essential essentials succinct:
http://www.sft.asso.fr/Local/sft/dir/us ... stique.pdf

traveling-wave thermoacoustic electricity generator
original:
http://arxiv.org/PS_cache/physics/pdf/0 ... 0086v1.pdf
more efficient:
http://www.springerlink.com/content/y33h67h067146367/

http://en.wikibooks.org/wiki/Engineerin ... oacoustics
http://data.mecheng.adelaide.edu.au/avc ... as2005.pdf
http://digital.library.adelaide.edu.au/ ... ers1-4.pdf
http://www.acs.psu.edu/thermoacoustics/ ... atents.htm
http://www.acs.psu.edu/thermoacoustics/ ... ations.htm

Serious articles published:
http://www.mendeley.com/research/a-100- ... generator/
I never put it because I see it for the first time.

There is a variety of English in memory.

The basic principles are those of the resonators, often 1 / 4 of wave size given by the speed of the sound 330m / s for the air and the quarter of the wavelength. like organs, flutes, 1 / 4m = 25cm = 330 Hertz, if at standing wave.
but there is a progressive wave, so a wider band.
Like feedback waves and oscillators, we can have very complex, chaotic modes of operation, such as electronics, radio, short wave and microwave, which I know better; but similar.

Then the impedance adaptation is crucial, with pipes of variable section, resonances, or even expansive flag, which have a broad band so well built and which exist in large industrial productions shown in photos, (similar technique to that in radio, and microwave that I know better).
This allows to adapt displacements and forces for the transducer which can be what one wants, if adapted, piston, membrane and coil speaker, piezoelectric.
http://fr.wikipedia.org/wiki/Onde_stati ... s_un_tuyau
http://fr.wikipedia.org/wiki/Imp%C3%A9dance_acoustique
http://fr.wikipedia.org/wiki/Son_%28physique%29
http://www.quarter-wave.com/Horns/Horn_Physics.pdf
http://fr.wikipedia.org/wiki/Tube_de_Kundt
http://fr.wikipedia.org/wiki/R%C3%A9son ... _Helmholtz
http://www.ventsdefolie.fr/Zeff/Articles/LCCCM07.pdf
http://petoindominique.fr/php/hp.php

http://fr.wikipedia.org/wiki/Tuyau_d%27orgue
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chatelot16
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by chatelot16 » 04/01/12, 19:55

I ended up finding interesting thermoacoustics, for this assembly exchanger and stack, but why not a single piston at each end, less bulky than the resonator

thanks to the fineness of the stack and the exchanger the piston can move at maximum speed ... no need to be limited to a low speed like the classic stirling

but I think it's already done! the fast-moving alpha stirling are more thermoacoustics at 2 piston than alpha

the alpha stirling generally described has a heated cylinder, a cooled cylinder, and a regenerator between the 2 ... I have always found it stupid to heat a cylinder: damage to the gasket

if there is a heat exchanger between the regenerator (which can also be called stack) the hot piston no longer has to be heated, it can even be cooled

the stirling apha that I found bad, becomes the best once treated as a thermoacoustic

these discussions on thermoacoustics have been very useful! I had left in the realization of beta to multiple cylinder ... the alpha thermoacoustic will be better and more economic to realize

and not the turn is not finished: the alpha has yet another defect: it is necessary to pass the power of displacement by the crankshaft, with loss and friction ... only a differential movement of the 2 piston is motor

the beta or gama engine has the advantage of moving without friction

the beta or gamma engine can also be transformed into thermoacoustics by putting a heat exchanger around the regenerator

once the exchangers are well placed as a thermoacoustic the cylinders no longer have a thermal role and it will turn as fast as the fineness of the exchanger and stack allows it
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by dedeleco » 05/01/12, 03:32

For the remark that the lamina flow engine is too fast compared to its piston, a high-frequency audio solution, piezo simple and well designed which has a better performance, if the frequency is the resonance of the piezo 3 6Khertz, piezo very little expensive, taken on alarm his piezo sold everywhere (0,5 €).
http://www.youtube.com/watch?v=SoKpkTRa ... creen&NR=1
and very simple construction details, but effective, with a good understanding of physics:
http://www.youtube.com/watch?v=7BfQVYQgJgk

I think this guy is trying to pin down the problems and optimize by remaining simple, before making bigger and more complex.
Nevertheless I do not understand how the lamina flow, at high frequency can walk with a piston low frequency, even a little, I think we must understand also better, the stack seems to work on all frequencies.

The piezo has a good performance at its resonance around some KHertz, to measure and adapt the impedance, but it allows to convert the high frequency of short tubes.


I think it is important to understand the very detailed operation in many scientific articles before deciding on the best solution.

A thesis study giving the theoretical bases and experiences of thermoacoustics:
http://alexandria.tue.nl/extra2/200112997.pdf
A summary :
http://kilby.sac.on.ca/physics/SPH4U/La ... 02002a.pdf
the best position of the stack in the tube:
http://murphylibrary.uwlax.edu/digital/ ... /128_1.pdf

the effect of different gases:
http://murphylibrary.uwlax.edu/digital/ ... /134_1.pdf
http://murphylibrary.uwlax.edu/digital/ ... /134_1.pdf

large ecological gear:
http://www.ecn.nl/docs/library/report/2005/rx05159.pdf

Not too expensive system:
http://data.mecheng.adelaide.edu.au/avc ... as2005.pdf

A powerful and recent system to watch closely in a prestigious magazine:
A high performance thermoacoustic engine
http://jap.aip.org/resource/1/japiau/v1 ... horized=no

ftp://ecn.nl/pub/www/library/report/2010/m10071.pdf
http://www.ecn.nl/docs/library/report/2011/m11061.pdf
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by chatelot16 » 05/01/12, 16:56

the motor lamina flow does not work at high frequency

an iron straw pad can not be used as a thermoacoustic stack

a good stack must heat exchange but let the sound wave without loss ... the iron straw completely stifles the sound wave

iron straw has only a role of thermal inertia

lamina flow is only a small toy engine that should not be mentioned as an example of thermoacoustics

the opposite is the sunmachine engine and incomprehensible with the usual description of the alpha engine: seen as a thermoacoustic piston is much clearer
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by dedeleco » 05/01/12, 21:06

If we talk about the same iron straw, very loose I do not think that
the iron straw completely stifles the sound wave

because full of holes very loose where air flows easily.
Iron straw can be stretched very easily to adjust the distance between the straw leaves to what you want.
therefore adjustable at least for simple tests.

It is necessary to quantify precisely by carefully reading physics on thermoacoustics, viscosity and thermal conductivity.
This is described in these articles already given by a characteristic length of viscous penetration which give the essential physical principles:
especially paragraphs 2 and 3,6 of:
http://kilby.sac.on.ca/physics/SPH4U/La ... 02002a.pdf
See as well :
http://murphylibrary.uwlax.edu/digital/ ... /134_1.pdf

It is necessary to calculate this delta (nu) = root (XNUMxxviscosity kinematic / (omega pulsation))
{rac = square root}
which must be smaller than the distance between walls of the stack, because otherwise the alternative flow is blocked exponentiellemnt.

kinematic viscosity = 15,6x10-6m2.s
http://fr.wikipedia.org/wiki/Viscosit%C ... %A9matique

and therefore at the period frequency T = 1s it gives a value very close to the thermal diffusion (19 to 20 against 15,6) is:
Root (15,6 / ft) mm = 2,2mm is 2,2.rac (T) mm

thermal gives delta (k) = rac (19 / ft) mm = 2,46mm is 2,46.rac (T) mm
http://fr.wikipedia.org/wiki/Diffusivit%C3%A9_thermique
http://en.wikipedia.org/wiki/Thermal_diffusivity

Also if the distance between the walls of the stack are greater than these distances (which decreases with the frequency) one is in the simplifying approximation of these articles:
The thermal and viscous penetration depths are smaller
than the spacing in the stack: dk; dm? y0. This assumption
leads to the simplification of Rott's
functions, where the complex hyperbolic tangents
can be set equal to one [1,3].


On the other hand, it is necessary that a large part of the gas is close to the thermal length for a good heat exchange and above the viscous one, which blocks near the walls, which is quite difficult considering their near equality !!
So the choice of the gas must be the one with delta (k) much higher than delta (naked), but not easy, because the physical phenomenon in the gas is the same for both, agitation of the molecules with average course and collisions which determine the viscosity (impulse transfer) and thermal (entropy transfer).
so it is written paragraph 3-6:
[b] As can be seen from Fig. 2 for a parallelplates
stack Imð? fkÞ has a maximum for rh = dk ¼ y0 = dk
¼ 1: 1. Since the spacing in the stack is 2y0, [/ b
]
therefore it is necessary at the optimum that the thickness of the stack plates is close to 2x1,1xdelta (k) is:
2,2x2,46.racT = 5,4.racT mm

So at high frequency like 100 Hertz with T = 0,01, the space between walls must be close to 5,4.racT = 0,54 mm
At 3 KHertz you need 5,4 / rac (3000) = 0,1mm
accessible in the iron straw a little stretched, adequately, to my impression.

Since a strong thermal gradient is required, a stack decreasing in total length with the frequency, (related to the wavelength) between the two extreme T's, is necessary to reduce the viscous losses.

These two videos pretty much respect these conditions:
http://www.youtube.com/watch?v=SoKpkTRa ... creen&NR=1
with the details of realization with 1mm stack of thick iron wool:
http://www.youtube.com/watch?v=7BfQVYQgJgk

So I think we need to do preliminary tests as on this video to understand and see concretely the effects of changes in dimensions and materials.
Nevertheless, it is certain that it is better to use tubes other than copper between the hot and the cold, which is too conductive of the heat, to have a good performance at the end.

More in detail:
http://alexandria.tue.nl/extra2/200112997.pdf
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by dedeleco » 06/01/12, 01:50

The fundamental bases necessary for a good realization:
http://murphylibrary.uwlax.edu/digital/ ... 3148_1.pdf

A simple and clear presentation:
http://ajp.aapt.org/resource/1/ajpias/v ... horized=no

The guiding principles, the problems solved, very fundamental also for an effective realization to know:
http://lanl.gov/thermoacoustics/Pubs/JASA03Cascade.pdf

important problems:
http://lanl.gov/projects/thermoacoustic ... eaming.pdf

A beautiful collection of possible different achievements:
http://www.lanl.gov/thermoacoustics/Pubs/ICSV9.pdf
http://www.lanl.gov/projects/thermoacou ... Pumped.pdf

useful info:
http://md1.csa.com/partners/viewrecord. ... cookie=yes

A big powerful system:
http://www.lanl.gov/thermoacoustics/Pub ... cwLAUR.pdf
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by bleusideral » 06/01/12, 07:21

it is exciting all this, very developed in metaphysical study, but pity that the docs are in English, too long to translate all this, are there not French versions?
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by chatelot16 » 06/01/12, 13:39

I am just able to understand what concerns me in these docs in English, but really not able to translate them properly

but no illusion ... there are interesting things, but diluted in many things to take with suspicion

the one who would have developed a good engine will not put everything in detail on the net for it to be made in its place

we only find documents presenting details on one part of the subject and generality on the rest, and it takes a lot of work to get something out of it

no internet document is enough for me to go forward ... the ideas that i devellope come from all origins, as much the old book of steam mechanics as the internet documents

I like the last one
http://www.lanl.gov/thermoacoustics/Pub ... cwLAUR.pdf

we see a methane-heated thermoacoustic engine coupling that produces sound for a thermoacoustic refrigerator that cools and liquefies methane: it avoids the weak point of thermoacoustics which is the conversion of sound to electrical or mechanical energy

they get results in% of methane burned compared to liquefied methane ... and the results seem to me worse than the conventional solution engine gas explosion and liquefaction classic compressor
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by bleusideral » 06/01/12, 14:51

= "chatelot16
but no illusion ... there are interesting things, but diluted in many things to take with suspicion

the one who would have developed a good engine will not put everything in detail on the net for it to be made in its place



I suspected it a little anyway, but it would take so long to translate everything by taking the "bandwagon" that it is not worth the trouble, however the subject remains in its basis highly interesting and necessarily to follow and develop : Shock:[/ Quote]
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by dedeleco » 06/01/12, 14:55

I mostly put the articles with the physical principles to assimilate and respect, accessible on the internet.
There are many more in magazines than with the abstract on the internet.
Almost nothing in French, and still English is the international language, but if the Chinese continue, we may need to learn Chinese one day!

Very important articles of discovery or performances are published in prestigious magazines which give the detailed publication only by paying !!

Industrial achievements copying without thinking and without understanding, are never given, especially with patents pending !!
But the physical understanding allows to reproduce respecting the different physical phenomena.

But even for pistons, it's crucial to understand the physical basis, otherwise poor performance, by misunderstanding of the stack physics, thermal, viscous, flows (streaming), diffusion lengths, thermal and viscous crucial, to always have in mind, etc.

So I insist, we must make the effort to understand physics and formulas, in English, since even the French publish in English and not the essential in French!
I think a cheap trial, like on the video can help a lot.

The google translation can help, at least not to turn the pages of the dictionary.
We learn and understand technical terms by reading many articles.
After useless to translate.
No sharp achievement can be achieved without reading English and sufficient basic physical and scientific knowledge.

I had a recent article with better performance than this big system already old, but only the abstract is available in the prestigious magazine (breaktrough):
http://jap.aip.org/resource/1/japiau/v1 ... horized=no
there must be a lot of information about the crucial elements of choice, clear to the specialists, protected by patent.

will be developed industrially
but it's already well developed since 30 years of industrial development and combined research.
In France the nuclear block the rest to to try to avoid a future Fukushima in France, inevitable, sooner or later, since men can not be infallible in perpetuity.
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