Thermoacoustic, how?

[dedeleco]

An article on the essentials of thermoacoustics essential for stacks with good performance on Stirling, in French which repeats, simulates and uses the published work more than 20 years ago in English:
http://hal.archives-ouvertes.fr/docs/00 ... 000235.pdf

Given the absence of moving parts, well created with simplicity, it's simple, a simple pipe and pores, with the right dimensions, a magnet with oscillating spring in a coil or piezo, it can be cheap and very reliable, mass-produced, and with good performance, better than 1 electric for 10, reaching 49% of Carnot cycle yield.

More the difficulty is to understand the physical functioning quite sharp, which explains why this physical phenomenon since 150 years has been used for less than 20 years!

The performance so well designed can reach 49% of the max yield of the Carnot cycle without moving parts and with simple parts !
A high performance thermoacoustic engine
http://jap.aip.org/resource/1/japiau/v1 ... horized=no

In thermoacoustic systems is converted into acoustic energy and vice versa. These systems use inert gases as working medium and have no moving parts which makes the thermoacoustic technology a serious alternative to produce mechanical or electrical power, cooling power, and heating in a sustainable and environmentally friendly way. A thermoacoustic Stirling heat engine is designed and built which achieves a record performance of 49% of the Carnot efficiency. The design and performance of the engine is presented. The engine has no moving parts and is made up of a few simple components

Finally a video of a very simple demonstration that makes electricity and that shows the basic elements , simple for just plumbing tips and fittings and a piezo alarm at less than 1 €.
http://www.youtube.com/watch?v=SoKpkTRa ... creen&NR=1
with the details:
http://www.youtube.com/watch?v=7BfQVYQgJgk

A little improved, understood physically, with tube with insulating portions not copper, agree on the piezo resonance, the yield can be interesting for the price.

[chatelot16]

I start to see the advantages of thermoacoustics: it allows to increase the performance in power per KG, but it leads to a complicated design, notament to a main part with a lot of welding to remain waterproof at high temperature

I ended up going back to my previous conception: a pile of small independent cylinder, without any assembly in the hot part ... all the assemblies are done by the cold part: if a cylinder fart by overheating its replacement will be a breeze

this principle will not give the best result in relation power poid, but the best in relation power price

and even better in longevity

with thermoacoustics, if a weld leaks at the hottest level, the repair will be difficult and may be impossible

I speak solar stirling or high temperature is essential for the performance ... it explains the best success of the thermoacoustic or the exchanger at low temperature are easier to build demountable

[dedeleco]

a note on the pistons:

if a cylinder fires overheating its replacement will be a breeze

We no longer use steam engines on trains, yet easy to repair by changing the piston, a "child's play" yet, very concrete, which does not require intellectual knowledge on Faraday and all the electromagnetism of TGV !!

Also I am not at all convinced by this argument to keep the old well known.
A multitude of pistons can not be cheap.

For cheap, which is sold in large numbers, it is necessary to study the development strongly, to make simple and reliable with modern astute techniques.

First step to realize the good conditions of operation and the best achievement remaining simple.

Then make it cheap, which changes completely at all according to the quantity manufactured.
The high temperature portion can be very localized with ceramics but 200 300 ° C are sufficient, and therefore solders will work in the first tests as on the video put.

If we target 900 ° C, everything changes and thermoacoustics, may be the only one possible without moving parts, is to be totally revised, because it becomes extremely difficult in materials, the glass being the simplest, as for the glassmakers, the first ones to observe the thermoacoustic more than 150 years ago.

[dedeleco]

Finally they made Stirling thermoacoustics with liquid sodium:

a Stirling thermoacoustic motor with liquid sodium is available in thermoacoustics for 700 ° C,

This remarkable Stirling with MHD, was probably taken by the military and NASA and became secret?

http://asadl.org/jasa/resource/1/jasman ... ypassSSO=1

A liquid metal thermoacoustic engine is studied both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts except the acoustic oscillations in the liquid metal. In the engine, heat flow from a high ‐ temperature source to a low ‐ temperature sink amplified to a standing acoustic wave in liquid sodium. This acoustic power is simply converted to electric power by means of a magnetohydrodynamic effect at the acoustic oscillation frequency. A detailed thermoacoustic theory applicable to this engine is developed, and it is found that a reasonably designed liquid sodium engine operating between 700 ° C and 100 ° C should generate about 60 W / cm2 of acoustic power at about 1/3 of Carnot's efficiency. Construction of a 3000 ‐ W thermal laboratory model engine is almost complete. A 1 ‐ kW, 1 ‐ kHz liquid sodium magnetohydrodynamic transducer has also been designed and built. It is now very well characterized both experimentally and theoretically. The first generator of its kind, it already converts to power with 40% efficiency.

[bleusideral]

can we in this case associate the sonofusion in this principle? where at least would there be an interest in taking advantage? I hope my question is not misplaced in the light of your knowledge

[dedeleco]

can we in this case associate the sonofusion in this principle?

Nothing to do in the current conditions.

The sonofusion is claimed and not certain because it is discussed in the sonoluminescence of bubbles in liquid water and not in liquid sodium.

So at the very different principle level, even at the frequency level of the sound (10 to some 100 Hertz for thermoacoustics in gases) and sonoluminescence tens of KHertz of a bubble in liquid water.

[FPLM]

Indeed, nothing to do with sonoluminescence in principle.
A small downside, however. While the absence of moving parts greatly simplifies construction and maintenance, it does not guarantee against wear. The frequency and amplitude of the sound wave (pressure difference) as well as the frequency and amplitude of the heat wave (temperature difference) could reveal in the medium term a more important or more "degrading" wear ( understand more difficult to repair) in materials subjected to these conditions in fine.

Are there any comparative studies on this aspect of wear in the medium term?

PS: Dedeleco, the thesis of nuclear fusion at the collapse of the bubble has been confirmed by researchers at the University of Chicago (I believe). They detected neutrons and especially tritium in water that was carefully lacking before. More and more exciting!

[chatelot16]

it is not only the life expectancy to be considered: there is the efficiency

they proudly announce 40% of the output of the sound to the electricity ... blah

with a good old piston, we easily obtain 95% of the pressure al "mechanical energy ... and a good alternator makes 85%

0,95 0,85 x = 0,80

of course the classic mechanics wears out, but if it's well designed, easy to dismantle with a cheap piece, maintenance does not cost too much

we must not be misled by a large machine, whose maintenance is too complicated, and the piece too expensive

for solar concentrating, it requires a high temperature: the life of the hot part will be limited by hot corrosion: conventional stirling or thermoacoustic will not change the life of the ... but will change the ease of disassembly

for now the classic stirling structure that I project is much easier to dismantle than what I can consider in thermoacoustics

it must be said that in classical stirling years ago that I am on top to optimize the architecture, while the thermoacoustics, I only discover it ... but we must make something, I will not delay the construction even more ... I'm going to do classic strirling, and for thermoacoustics we'll see later

[FPLM]

Yes Chatelot, that's true, but it should be noted that thermoacoustics remains "exotic" and is still in its infancy. Initially, the mechanical yields were just as poor. The choice of materials, gases, working pressures, etc. Perhaps thermoacoustics will evolve if serious experimenters are interested.

[bleusideral]

Hello
when you talk about wear, life of moving parts, what materials do you talk about? (I suppose aluminum, steel, copper ... classic)
There are differences between its materials which are not of caloric conductivity only, but also dilation and abrasion wear, friction, ...
In a "classic" Striling, is it possible to use more neutral and almost indestructible materials, I think as an example, ceramic (unless I am wrong about these said performances, I did not do extensive research!) used in areas where caloric performance is required.
in this case I do not think of the costs of realization because I think above all reliability, more profitable concept.