From Stirling engines to thermoacoustic generators

[greybeard]

Has anyone yet made a start at trying their hand at a "TAG" ?
I'd been refreshing my interest in Stirlings as a preparation for this summer's project(assuming the cnc is ready to cut parts for the solar dish ) when I noticed a lot of the university and patent links of the last few years keep referring to thermoacoustics.
I'd had a discussion about 18 months ago on this topic with Evodyne, and decided to re-read what he'd sent me.
The latest work I've come across looks very promising, and with only one moving part - the vibrating magnet assembly for the generator - is enticing to consider.

Has anyone else any ideas/thoughts on this development ?
Regards all,
John

[delt0r]

There was a big boost in interest with the gas industry in the US. The idea was that they could use them at the pumping stations and have no moving parts. Efficiency is however very low in every paper on the topic i have read. I am about 6 or so months out of the loop tho.

My original interest was the other way round. Pulse tube cryo coolers. Very cool.

If you get stuck getting hold of a paper, sing out. I still have all the PDF's somewhere in my backups.

[greybeard]

Originally Posted by delt0r ...................If you get stuck getting hold of a paper, sing out. I still have all the PDF's somewhere in my backups.

Thanks, deltOr, that's a kind offer that I'll bear in mind.
Regards
John

[greybeard]

For anyone not familiar with the technology, a good starting point might be the link below. It's very easy reading.
After that, googling "thermoacoustic generators" produces a lot of information.

John

http://www.americanscientist.org/tem...e/3?&print=yes

[greybeard]

DeltOr - have you ever come across any reference to the use of a fluid filled TAG ?

I wondered if such a device would be possible, or have any advantages over the gas filled devices vis-a-vis the increase in heat capacity.
Just a thought.

By the way, re your pdfs of papers, do you have a list, or could you send me a screen shot of the list ?

Regards
John

[delt0r]

Fluid filled? No, you won't get adiabatic compression that matters, hence little or no work done. Unless the is a fluid and a gas, but then the fluid would not provide better thermal contact than any other solid.

So the real answer is that no i did not see any with fluid in them.

As for the PDFs. Well as a physics guy I read a LOT of papers on a lot of topics. Now as someone working in Bioinformatics I have a lot of papers on that two. I have about 10+gig of pdf's. The problem is i did not organize them properly. I even wrote a tool to try and search them. But finding things is slow.

However i will have a bit of a search over the next few days.

[delt0r]

I could only find a few old pulse tube cryocooler papers. Most must be back at work in my archive. That will take some time. But i did google a little just to see how far out of the loop i was.

I found this: http://www.nature.com/nature/journal.../399335a0.html

I have downloaded it so could email to you (Private msg me?). They boast 30% effenciy. Pretty high.

Oh and the coolers that I was interested in became popular because they can be used to liquefy natural gas.

[delt0r]

One of my posts has gone missing.... I will repeat a little of what i said.

First was that liquid does not work because you don't get the adiabatic heating. Or expansion on heating.

2nd. All my pdfs are very disorganized. I will see what i can do before i head of to nz in a week.

[greybeard]

Had a quick look at the Nature article. The authors have done a lot of work since, some published in patent applications etc.
A recent patented work I've found,(different authors), is US pat. no. 2006/0119224 where they talk of a Carnot efficiency of 49% !

Thanks for the heads up on liquids - it was an idle musing on my part, but who knows.
I do have a reputation for crazy ideas I have to protect.

pm coming.
Regards
John

edit I think that figure is 49% of theoretical maximum at the given temperature differential, not overall efficiency of conversion!

[greybeard]

Update on my original question.

Given that there is a lot of information on a variety of methods to get from solar radiation to power, be it electricity or motive power, my first direction is to build a solar collector, most likely a dish, given my location and space available.
With that set up at the bottom of the plot, I can then try a variety of methods and compare results.
Having said that, it is immediately obvious that two identical mirrors would make the comparisons a lot easier, so thats what it will be.
Prototype collector is to be a 3' x 2' x 1/16" ply sheet cut and formed to an approximate parabola with an aluminium foil surface. This will be to check my construction method/maths etc, then two mirrors using 8x4 sheets should follow in short order.

Then the fun will really start, so the cnc construction had better make some progress as well.

[epineh]

Interesting concept John, I will be interested in how this goes. I don't really understand the concept (yet) but it sounds like a challenge, I have always thought it would be nice to harness some of the noise around this place, with 3 kids and a Pug dog we have a plentiful supply

Russell.

[Ferny]

Delt0r, You made me laugh! Thanks!
I once worked for a physicist who was very unorganized to say the least.
Every prototype device looked like an explosion of clip leads, the lab cabinets overflowed with equipment, his office had stacks of papers strewn about with tall piles leaning... ready to fall over. Perhaps you can can relate?

Now that I think of it out of the half dozen I have known, all but one is organized!
It's OK, with all that heavy duty thinking going on!

I sure do like working with physics guy's since I am continually learn new things.

Thanks for the visual,

Ferny.