Générateur thermoacoustique

[Remundo]

Salut Nlc,
Sur

http://www.savoirs.essonne.fr/dossiers/ ... sources=1#

Il y a une vidéo qui explique très bien le principe du RTA (réfrigérateur...thermoacoustique)

Et comme cela peut fonctionner à l'envers... c'est aussi un GTA !

Il y a plein de liens intéressant sur cette page...

[nlc]

Froid ton lien !!

Enfin, je veux dire cool ton lien

Surtout cet article : http://www.americanscientist.org/templa ... 006/page/1

7 pages à lire, je viens de finir la page 2

[Remundo]

Oui, ça c'est pas mal (extrait de ton lien)

Figure 4. Thermoacoustic engines are similar to optical lasers in that both types of apparatus amplify standing waves set up within resonant cavities. In a ruby laser (top), for example, energy is added by means of a flash tube, which creates a "population inversion" of electron energy levels. In the thermoacoustic analogue (bottom), energy is injected into the cavity using the heated stack, which creates a nonequilibrium temperature distribution.
Tom Dunne

[Remundo]

ça aussi c'est très bon... Le stack jouerait le rôle de régénérateur... il il faudrait chauffer le tube d'un côté, et refroidir de l'autre...

Figure 7. Stirling cycle contains four distinct steps—compression, heating, expansion and cooling—which produce a characteristic set of changes in pressure and volume (right). In a simple, two-piston Stirling engine (directly below), the compression step (1) keeps one piston fixed as the other moves inward, the heat of compression being rejected into the adjacent cold reservoir. The next step (2) produces constant-volume regenerative heating, as both pistons move simultaneously, forcing cool gas through the porous regenerator, which was heated during the final step of the last cycle. Next (step 3), heat from the hot reservoir causes thermal expansion of the gas, which forces the adjacent piston to move outward. Finally (step 4), both pistons move together to create a constant-volume regenerative cooling of the heated gas. The changes in pressure and gas velocity within the regenerator of such a Stirling engine mimic the relationship seen in a traveling acoustic wave, where pressure and gas velocity move up and down in phase (bottom pair of panels).
Tom Dunne

[Remundo]

Je mets ça aussi !

Figure 8. Traveling-wave heat engine that Peter H. Ceperley envisioned more than two decades ago amounts to a loop of gas-filled pipe with one or more porous regenerators inside. Heat exchangers attached to each regenerator supply heat or carry it away, setting up thermal gradients (solid arrows). In this configuration (adapted from Ceperley's 1979 patent), one regenerator is meant to amplify the traveling acoustic wave (dashed arrow), while the second provides useful cooling. Although Ceperley was never able to construct a working traveling-wave engine, T. Yazaki and three Japanese colleagues described in 1998 their success in building such a device to compare the properties of traveling- and standing-wave thermoacoustic engines.
Tom Dunne

[Capt_Maloche]

C'est le principe du laser

par contre côté rendement, un réfrigérateur traditionnel à compresseur à un COP de 4, alors qu'avec la thermo-acoustique on sera en dessous de 1

faudra choisir

[Remundo]

Salut Captain !

Et oui, côté rendement, le bât blesse apparemment... mais il y a de la simplicité technique, c'est ce que Nlc recherche

[Capt_Maloche]

ça aussi c'est très bon... Le stack jouerait le rôle de régénérateur... il il faudrait chauffer le tube d'un côté, et refroidir de l'autre...

excellent ! ç'est le principe du pseudo stirling sur la photo de lapage précédente

[Remundo]

Enfin page 5, ils disent avoir trouvé un truc, un genre de "valve anti-retour"... qui mettrait les performances au niveau des moteurs actuels...

http://www.americanscientist.org/templa ... ge/5#23077

Once we realized what was happening, it was easy enough to correct the problem. One solution (which Ceperley had suggested years earlier for his circular design) would be to add a flexible membrane that passed acoustic waves yet blocked the continuous flow of gas. But prior experience with such membranes led us to believe that it would be hard to engineer something sufficiently robust to hold up over time. So instead we added a jet pump (asymmetric openings that allow flow to pass in one direction more easily than the other) to create a slight back-pressure in the loop, just enough to cancel the streaming. And we were pleased to find that the efficiency of the engine improved markedly. At best it ran at 42 percent of the maximum theoretical efficiency, which is about 40 percent better than earlier thermoacoustic devices had achieved and rivals what modern internal-combustion engines can offer.

[Remundo]

Peut-être du nouveau dans le domaine de l'énergie thermoélectrique

http://www.heat2power.net/en_benchmark.htm
http://www.auto-innovations.com/actualite/1118.html

Rendement affiché par le lien anglais 17% (à confirmer + hyptohèse sur les températures...)

BMW lance des projets sur la récupération de chaleur à l'échappement