Why are their no big LTD Stirling Engines

[Adam Norris]

I am new to this sector, but have now got 5 LTD toy Stirling Engines. I do not understand why no one has built a big one yet. Please can someone tell me why.
Thank you

[Ian S C]

Adam, look up a PDF about the Canterbury (NZ) University studies on large power generating LTD Stirling Engines. Power generating Stirling Engines are large and heavy, LTD engines require to be larger to produce usable power. Ian S C

[vamoose]

Hey Adam,

There aren't a whole lot of them around but they do exist.
Its harder to get efficient power conversion from a low temperature difference.
The bigger the delta t (hot/cold temp difference) the better the efficiency and potential power output.

check out this one
http://www.youtube.com/watch?v=AIA12_GxVws

or this one
http://www.youtube.com/watch?v=LuTs5yqH0J8

another cool/hot one
http://www.youtube.com/watch?v=0sa_-SaB0Zg

Here's a more powerful one that has potential commercial applications,
They have also produced other versions of this engine for pumping water and other applications.
http://www.youtube.com/watch?v=SMMELH7CSNE

This german guy has made some excellent designs also
If you dont want to watch the whole video then skip to 59 seconds, then next to 2min 15 seconds
(but watch the whole video if you have the data and the time)
http://www.youtube.com/watch?v=TZjCOlDDW0Y

This fellow has made a couple of interesting larger engines but they're not LTD's
http://www.youtube.com/watch?v=eIxl-2ZZVfs
http://www.youtube.com/watch?v=9jQgAnPrwbM

(there are a few more scattered around the net)

In regards to your other post re- graphite piston, maybe you could consider a diaphragm or bellows type power piston like the ones in the german video.

If you intend to make a large LTD engine then that is an awesome idea. I'm not sure if anyone on the forum has done so yet. But as you can see, it is definitely possible to achieve.
I'd suggest that people on the forum would help as much as possible if you were to undertake such a project..

vamoose

[theropod2]

vamoose,

in the German version are those bellows not the bladders for truck air ride suspensions, or something similar?

R

[fullofhotair]

What determines an LTD ? How large a temp. difference can you have ? I wonder if they use a regenerator on those large ones. I saw a small LTD . He stated he made a hole in the styrofoam displacer and added a few layers of brass screen, for a regenerator. He said it made a big difference. Almost all the large LTDs I have seen use a styrofoam displacer. I wonder if you go larger, maybe a hollow displacer might be better.

[Ian S C]

My definition of LTD is a motor running on a heat source not too much greater than boiling water, ie in the range where Styrofoam can be used with out melting.
For a large, hollow displacer, Balsa would seem to be quite a good choice, although many other wood venire, or thin ply wood as used in model aeroplanes might be good. Ian S C

[fullofhotair]

I wonder what the largest LTD is ? I think I have seen a couple larger than Vanoose's posts. I believe it was at a fair or something. I can't seem to find it though. Someone thought it was Alien technology because they didn't see a heat source or fuel tank. It was unfocused, solar powered. Just a black absorber.