Search found 131 matches

by Bumpkin
Thu Apr 19, 2012 1:13 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: RTV diaphragm
Replies: 2
Views: 2615

Re: RTV diaphragm

Thanks Junkie. Did you use anything between the balloon and the rtv? I would have thought they would bond tighter than that. Neat video, though it's been a half-hour and I can't get past 0:47. I almost never watch videos because I'm on dial-up and usually get more out of diagrams anyway, but I alway...
by Bumpkin
Wed Apr 18, 2012 11:38 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: RTV diaphragm
Replies: 2
Views: 2615

RTV diaphragm

Has anyone here made their own custom diaphragm by layering fabric and rtv or plain silicone? It'd be nice to be able to make the exact shape and weave-strength orientation you want. You could even cast in some metallic portions. Any tips?
by Bumpkin
Sat Apr 14, 2012 9:42 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Elegant solution for the rod seal
Replies: 9
Views: 5836

Re: Elegant solution for the rod seal

Ian, the displacer won't hit the sides. The limited amount of rocking is a factor of how long the rod vs. how short the displacer, relative to the effective pivot point. I do admit though, to having difficulties getting enough diaphragm flexibility while maintaining enough lateral strength. I could ...
by Bumpkin
Fri Apr 13, 2012 8:48 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Elegant solution for the rod seal
Replies: 9
Views: 5836

Re: Elegant solution for the rod seal

Hi Alex. I'm working on electricity from a woodstove too. My seal is sort of "elegant," but I've no idea yet if it will work. My displacer design uses a short stroke so the rod can move with a diaphragm, which also allows it to rock a little bit so there are no extra joints needed in the rod to the ...
by Bumpkin
Wed Apr 11, 2012 11:59 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Stirling Turbine
Replies: 48
Views: 31576

Re: Stirling Turbine

Hi Tom. I didn't know that about Tesla. Good company indeed. I don't know if I understand you to mean that you could collect energy by simply exhausting the cold gas - the temp drop doesn't represent power until it collects ambient heat, a process that would in that case happen externally and be tot...
by Bumpkin
Thu Mar 15, 2012 8:27 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Engine vs. heat pump
Replies: 2
Views: 2480

Re: Engine vs. heat pump

Thanks Ian, that’s what I was thinking, but couldn't see it that clearly. Looking at it as the same heat pump, whether it's driving or driven, helps visualize. It would seem then, that if you throttle an engine by using variable displacer timing, if you took it far enough you could have a regenerati...
by Bumpkin
Wed Mar 14, 2012 9:43 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Engine vs. heat pump
Replies: 2
Views: 2480

Engine vs. heat pump

With consistent direction of rotation, which end of a Stirling gets hot when it's powered as a heat pump instead of making power as an engine? I'm thinking it would be the same as an electrical motor/generator situation where the polarity is the same, but the more I think, the less sure I am. I'm ju...
by Bumpkin
Tue Mar 06, 2012 12:10 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: displacer insulation
Replies: 8
Views: 4969

Re: displacer insulation

Thank-you both. I've taken my own thread off topic. I'd still like to hear anyone's other suggestions for insulation. I thought about expanding foam, but that's probably not a good idea in a hot chamber. Currently, the partition idea seems most likely, but difficult.
by Bumpkin
Sun Mar 04, 2012 3:37 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: displacer insulation
Replies: 8
Views: 4969

Re: displacer insulation

Ian, I admit I have little experience and a lot to prove, but I don't think there could ever be one ideal displacer shape. If I were to scale down to a 7" long by 3" dia. displacer, it would roughly match your ratio, but would still only have the same regenerating length as what I already have, and ...
by Bumpkin
Sat Mar 03, 2012 2:48 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: displacer insulation
Replies: 8
Views: 4969

Re: displacer insulation

Ian, thanks for responding. My list of compromises is already long and I don't want to add more than I have to. Isolation instead of insulation is a good idea, it's just that I already welded up my displacer before realizing the problem. It's a small air-compressor tank cut to length, with one end i...
by Bumpkin
Fri Mar 02, 2012 2:51 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: displacer insulation
Replies: 8
Views: 4969

displacer insulation

Hi. New guy here, glad to find folks of like interest. Does anybody insulate the inside of hollow displacers? I think the air flinging about in there would carry a lot of heat to the cold end. Convection inside a long narrow displacer wouldn't be as severe, but mine is 12" dia. X 7". Are there any p...