Thermal lag plans

[derwood]

Here is a picture tutorial for building the big thermal lag engine. If you have any questions just ask. The file was too big to upload directly to the site.

https://www.mediafire.com/?hdbcbnj9d2f8sdc

[Babblu]

Thanks for reply Ian S C, i have startet to do what you said, i have shaved about 1.3mm of the inner walls of the Displacer, and now it is about 0.6mm thick.i need get it in the 4 jaw chuck if you mean that i need to have thinner Displacer walls..i will make the lid of aluminium and i am thinking to gas weld my center hole, cause you said, that it would been best if the piston rod is mount in the lid/aluminium lid..

[Ian S C]

Babblu, I think you'v got the wrong thread. Ian S C

[cbstirling2]

Derwood,
I saw your engine on youtube. Looks cool!
Looking at your plans, why the need for the inner tube?
I guess, I do not understand the theory of it.
Does it act as a choke??

[derwood]

The gap between the inner and outer tube is the stack. The inner tube is for expansion. The gap between the inner and outer tube needs to be as small as possible without restricting flow.

[cbstirling2]

If I understand the pictures directly from your design, the inner tube point is aimed towards the piston. This would force the air to go along the outside and then into the expansion chamber as you mentioned. So in effect that would double the length of the tube? Because if I understand simpler thermoacoustic engines, they don't have that novel feature. Instead at the end of the heating tube, they just stuff copper wool which acts as a regenerator heat exchanger.

Did you base that design feature off of a particular article or another engine design that you read about? I'd be interested in seeing that original article as I'm trying to understand the theory of your engine.

[derwood]

I based it on a video posted here a while back. The member who posted the vid was Geoff V. It was a much smaller version but he never provided any dimensions. Through trial and error I managed to produce a larger version.

[derwood]

I just purchased a tig welder and as soon as i learn how to use it i will try some multiple tube designs. I am currently practicing welding .25 inch ss tubing.