Search found 280 matches

by Bumpkin
Tue Dec 05, 2023 9:19 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

“Did I explain this in a way you can understand my thoughts? Any thoughts on this?” The first, sorta. The second, maybe; as in I hope my participation in the thread didn’t contribute to your delinquency towards other responsibilities, whilst you pursue the sick madness of hot-air engines. I don’t ge...
by Bumpkin
Tue Dec 05, 2023 10:23 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: "Thermoacoustic" Stirling - theory of operation
Replies: 129
Views: 162127

Re: "Thermoacoustic" Stirling - theory of operation

Tom, that was a long ride on a horse I thought we beat to death years ago. You were there. I agree those sample videos you posted at the top are “Lamina” type, because of the nozzle that’s used to produce a (sort-of) laminar flow. They’re definitely not acoustic and definitely not Stirling. So I wis...
by Bumpkin
Mon Dec 04, 2023 11:15 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: "Thermoacoustic" Stirling - theory of operation
Replies: 129
Views: 162127

Re: "Thermoacoustic" Stirling - theory of operation

For interest in real thermo-acoustic engines I’ve referenced forum-member Tibsim’s site a few times. There are some neat videos at the bottom of this page: https://tibsim-thermoacoustics1488.blogspot.com/

Bumpkin
by Bumpkin
Sat Nov 25, 2023 1:33 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

Jack, if I’m figuring your idea right, it might be similar to the working principle of the Ericsson engine. In that design there isn’t a dead-volume penalty for as large a heater as you want. It ran open-cycle so it didn’t need a cooler. It reciprocated and had a regenerator, but if you did run open...
by Bumpkin
Tue Nov 21, 2023 10:27 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

Had a few brews tonight so maybe this is a bit too honest, but I was about to post something rude before I finally saw what smarter folks would obviously see; the second diagram of the hot rotor isn’t idiotic because it squishes a volume down to nothing; It’s idiotic because it doesn’t show a flow p...
by Bumpkin
Thu Nov 16, 2023 12:42 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

I seem to remember seeing some rotary displacer designs that thermally coupled the opposing zones between the hot and cold zones for a degree of regeneration, with an external thermal bridge of conductive metal. As I see it, the whole chunk would have to run at about the same average temperature bet...
by Bumpkin
Tue Nov 14, 2023 9:41 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

More ran-dumb thoughts: Yes reciprocating stuff is crude, but reciprocating the working gas is the only way regeneration works as far as I know. Stirlings basically got put out of business by engines that don’t use it though, so… I think the vane pump could make an engine on it’s own without any oth...
by Bumpkin
Sun Nov 12, 2023 11:48 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: I'm planning to build a Stirling generator to work off heat from our kitchen stove.
Replies: 85
Views: 137839

Re: I'm planning to build a Stirling generator to work off heat from our kitchen stove.

Random thoughts from someone over forty years off-grid: I believe the engine linked to in the top post is the double-acting type, so a diaphragm would be difficult. I like the rotary displacer idea for simplicity. Since it eliminates regeneration it’s not really a Stirling, but that could be good or...
by Bumpkin
Wed Nov 08, 2023 10:57 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Working Principles of Lamina(r) flow thermoacoustic engines
Replies: 4
Views: 7309

Re: Working Principles of Lamina(r) flow thermoacoustic engines

I could well be wrong, but the lower frequency and the nozzle design of that engine suggests to me that it is a thermal lag engine. Tibsim’s site has some interesting thermoacoustic stuff. The videos at the bottom are interesting.
https://tibsim-thermoacoustics1488.blogspot.com/

Bumpkin
by Bumpkin
Sun Oct 08, 2023 11:15 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Rarefication
Replies: 33
Views: 20732

Re: Rarefication

My two cents: I’ve always thought of the “heat is molecular motion” theory to mean internal atomic motion in the molecules actually makes them bigger so they push out on their neighbors a bit, but then stop until they get fatter or skinnier. Such as a Gamma displacer could run a piston through a tub...
by Bumpkin
Sun Oct 01, 2023 12:25 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

Hadn’t noticed you’d posted again before I answered your prior. Thanks for those examples.

Bumpki
by Bumpkin
Sun Oct 01, 2023 12:21 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

In the horizontal-movement displacer Ringboms, it’s the pressure swings alone that move the displacer both ways. (I think that’s a good demonstration of Stirlings being one-stroke engines.) I was just thinking that for a vertical movement displacer, balancing the weight might have some minor affect,...
by Bumpkin
Sun Oct 01, 2023 12:41 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

Well, the displacer could start to move before the power piston is at optimal timing — but I agree; as soon as the DISPLACER starts to move, a portion of the air is heated or cooled which increases the pressure difference, which increases the movement, which increases the pressure difference… a chai...
by Bumpkin
Sat Sep 30, 2023 9:33 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

Just a couple more months of wood-cutting before I can spend some of the winter break fooling around with this again. Before snow covers everything up, I need to locate and stash whatever parts or materials I might need from my local “Hardware store.” (My backyard full of assorted obtainium.) So I n...
by Bumpkin
Tue Sep 26, 2023 8:28 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Constant volume compression/expansion-displacer chamber analysis-heat powered mechanical amplifier
Replies: 45
Views: 21509

Re: Constant volume compression/expansion-displacer chamber analysis-heat powered mechanical amplifier

“As the gas is transferred at zero total volume change from the cold space to the hot space the pressure rises. This pressure rise results in a temperature increase in the gas due to adiabatic compression. Therefore, at the end of the transfer process the mixed mean gas temperature in the hot space ...