Search found 280 matches

by Bumpkin
Tue Apr 27, 2021 9:01 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Liquid piston Stirling engines (Fluidyne)
Replies: 2
Views: 2222

Re: Liquid piston Stirling engines (Fluidyne)

I would think that closing a fluidine from atmosphere to raise it’s working pressure might have the same benefits as with other Stirlings, except that liquid piston engines are generally (exclusively?) used for water pumping and the internal pressure might offset the pumping process. If you got this...
by Bumpkin
Sat Apr 10, 2021 9:45 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Liquid Heating/Cooling of Hot/Cold Alpha Stirling Engine Cylinders?
Replies: 82
Views: 47669

Re: Liquid Heating/Cooling of Hot/Cold Alpha Stirling Engine Cylinders?

You could perhaps look into oil-bath air cleaners as donor technology. They used to be fairly common but are somewhat rare now - (perhaps because of too much pressure drop as the air bubbles through the oil?) Remember 150 f. to 50 f. is only about a 20% absolute temperature difference, so there woul...
by Bumpkin
Tue Feb 23, 2021 2:08 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: new concept of Stirling engine
Replies: 62
Views: 20524

Re: new concept of Stirling engine

Some interesting posts here have led me down a rabbit hole for the last hour or so. Sharkskin, owl feathers, golfball dimples, vortex cannons... Don’t reckon I’m any smarter than when I started, but some random thoughts: The sharkskin is directional and lowers resistance by keeping the flow more att...
by Bumpkin
Wed Feb 17, 2021 10:12 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hybrid Thermoacoustic Stirling Engine
Replies: 33
Views: 17616

Re: Hybrid Thermoacoustic Stirling Engine

“The burning of hydrocarbons, the resulting CO2 emissions, is fueling global-overheating that is rapidly bringing us to the Anthropic Mass Extinction, which has already begun. Humanity is unlikely to survive that mass-extinction.” I’m not some leftist who feels it necessary to censor opposing speech...
by Bumpkin
Mon Dec 21, 2020 11:46 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot air engine heated by magnifying glass instead of flame?
Replies: 6
Views: 3437

Re: Hot air engine heated by magnifying glass instead of flame?

Hi Cavalier68 Remember that solar heat needs a good absorber before it can then conduct to air. Some solar Stirling engines purposely have windows into an internal heater matrix. If your engine is only glass at the heated portion, maybe you could just blacken it. It would still be difficult to direc...
by Bumpkin
Tue Dec 15, 2020 10:14 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hybrid Thermoacoustic Stirling Engine
Replies: 33
Views: 17616

Re: Hybrid Thermoacoustic Stirling Engine

Hi Tristan. Nothing intelligent to add here other than no, L.T.D. in this context stands for"Low temperature difference" You probably know that but in the Forum's interest we need to try to be accurate. You're engine is quite interesting.

Bumpkin
by Bumpkin
Wed Dec 09, 2020 7:33 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: job opportunity
Replies: 5
Views: 3316

Re: job opportunity

Hi bbrennan. For your solar purposes I think you're way too late to compete with photovoltaics. If you're interested in disposing of surplus development money though, I could help. Seriously though, I wish you well. I just hope you have realistic goals.

Bumpkin
by Bumpkin
Mon Dec 07, 2020 8:48 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Gamma Stirling operations through the cycle
Replies: 1
Views: 1857

Re: Gamma Stirling operations through the cycle

Hi. Fortunately the Gamma is the easiest to understand. This isn't the best I've seen but it shows the basics pretty well.
https://www.youtube.com/watch?v=LRN5o9qVL8w Not much time now but I'll check back in if you want to let me know if it does you any good.
Bumpkin
by Bumpkin
Sat Nov 28, 2020 11:35 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Gamma Stirling Engine Power Piston Bore to Stroke Ratio
Replies: 4
Views: 2913

Re: Gamma Stirling Engine Power Piston Bore to Stroke Ratio

Hi Andy. Most of the same considerations apply as to other engines; friction vs. displacement vs. sealing. Flow, dead-space, vibration, packaging, and your own manufacturing skill and available materials figure too. The square bore/stroke ratio is probably common for good reason, but there's nothing...
by Bumpkin
Tue Sep 22, 2020 11:00 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: LTD magnetic vs gamma
Replies: 95
Views: 21982

Re: LTD magnetic vs gamma

I didn't mean to say that the rapid displacer movement is bad, but simply that there are trade-offs. I should have been more clear. It seems likely that dwell time is more important than any loss to aero or regeneration loss. I was thinking after my previous post about the return of energy to the cr...
by Bumpkin
Sun Sep 20, 2020 7:52 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: LTD magnetic vs gamma
Replies: 95
Views: 21982

Re: LTD magnetic vs gamma

I had to search it. If what I saw is the same as what you're talking about, it looks very similar in principle to a Ringbom type engine. Advantages: They don't need a separate crank linkage to the displacer, they have a period of dwell at the heating/cooling ends, they're reversible, and sometimes t...
by Bumpkin
Thu Sep 10, 2020 8:56 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: The Right Theory of the Real Stirling Engine.
Replies: 23
Views: 16111

Re: The Right Theory of the Real Stirling Engine.

Sadi, could you clarify your definition of the Stirling Cycle?

Bumpkin
by Bumpkin
Wed Sep 09, 2020 9:31 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Lubricating oil
Replies: 1
Views: 1562

Re: Lubricating oil

Hi Surreypuma. I can't speak for one brand or type, but I think some of the bike chain lubes have a sticky formula to keep them from flinging off, and it might be too much friction in minimal power engines. The "dry" lubes might work well for bearings but maybe not for the seal for a displ...
by Bumpkin
Mon Sep 07, 2020 11:41 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: The Right Theory of the Real Stirling Engine.
Replies: 23
Views: 16111

Re: The Right Theory of the Real Stirling Engine.

Sadi, could you clarify your definition of the Stirling Cycle? I consider it to be represented by a closed-loop regenerating heat engine. Numerous sources credit Robert Stirling with that development. (I like the book "Air Engines" by Theodor Finkelstein and Allan Organ.) You're probably a...
by Bumpkin
Tue Sep 01, 2020 9:32 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Rarefication
Replies: 33
Views: 20732

Re: Rarefication

I agree it looks like in the top video, that the internal pressure needs to drop to get the engine going, but I think it's because it needs to (on average throughout it's cycle) balance with the external atmospheric pressure to get "over the hump." I suspect that if the engine were encased...