Search found 280 matches

by Bumpkin
Tue Sep 26, 2023 7:49 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

The Ringbom displacer stroke length finds its own way, solving math problems for lazy folks like me. Anyway, it fills in the Beta strokes from each end, and allows experiments with different displacer thicknesses. I think a kinematic linked displacer COULD be more efficient, but the timing exactitud...
by Bumpkin
Sun Sep 24, 2023 9:31 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

Sorry for the late reply, computer troubles. Anyway, I’ll get back to this next winter, but for now the displacer and its drive and the crankshaft placement are imagined in. It’s drawn to scale on the graph paper with one square to an inch. I didn’t draw the long tandem connecting rods that’ll go up...
by Bumpkin
Sun Sep 10, 2023 10:02 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: The Carnot efficiency problem
Replies: 258
Views: 118535

Re: The Carnot efficiency problem

A lot of folks gave us a great foundation, but I can’t believe any designer would be worse off for never having heard of Carnot or some others. For instance — Stirling didn’t need to think of heat as molecular motion instead of “caloric” to understand its affects. He didn’t need Boyle’s law to under...
by Bumpkin
Fri Sep 01, 2023 11:00 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Constant volume compression/expansion-displacer chamber analysis-heat powered mechanical amplifier
Replies: 45
Views: 21508

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

Joining in late here, but in my way of thinking, turbulence is convection. But no matter the wording I’m sure we agree that the air and the heat have to somehow get cozy with each other in a timed process. I know I’ve harped on it for years now, but I think we should give radiant exchange more consi...
by Bumpkin
Wed Aug 23, 2023 9:03 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: 60L drum medium temp Gamma build
Replies: 27
Views: 13971

Re: 60L drum medium temp Gamma build

I’ve thought about brake canisters for years since being an old trucker. Cheap easy durable. They seem overbuilt for atmospheric pressure engines, but they could take nearly X 10 reliably. Not my thing, but just saying…

Bumpkin
by Bumpkin
Sat Aug 12, 2023 6:57 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Modified Gama cycle(cold hole/ambient scheme warning)
Replies: 13
Views: 5498

Re: Modified Gama cycle(cold hole/ambient scheme warning)

There’s at least one way to make a turbine that’s not directional and eliminate the need for check valves. I’ve pondered a twin rotary displacer engine with a flat flexible-vane fan-type turbine between. It would turn the same direction no matter the air flow direction.

Bumpkin
by Bumpkin
Fri Aug 11, 2023 9:22 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Displacer hot space vs cold space study
Replies: 19
Views: 3124

Re: Displacer hot space vs cold space study

Matt, the “A-B-C” graph shows both pistons topped out so I’m guessing you’re dispensing with the usual 90 degree linkage and are assuming full displacer travel, then full power piston travel, and so on. So in the position shown, the displacer is about to move the air to the hot side and then the pow...
by Bumpkin
Sat Jul 29, 2023 7:10 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: regen vs volume ratio graph
Replies: 11
Views: 9158

Re: regen vs volume ratio graph

I’m sure I’ve posted this here somewhere before, but this reminds me of noticing how mid to lower temperature engines of higher displacement ratios suffer less from dead space than higher compression high temperature engines. Of course it’s still a penalty, but low enough that alternate architecture...
by Bumpkin
Sun Jul 09, 2023 7:48 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Carnot reveal for Tom
Replies: 162
Views: 172983

Re: Carnot reveal for Tom

Not a fan-boy, but I like Tom well enough — I can’t imagine why some Jackass would say he needs to “prove” what he has observed. Prove the obverse or shut the H. up. And if Matt has concluded an ambient engine is possible (I haven’t seen that, but obviously that’s what a no heat rejection engine lea...
by Bumpkin
Tue Jul 04, 2023 6:52 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Carnot reveal for Tom
Replies: 162
Views: 172983

Re: Carnot reveal for Tom

“Nobody’ wrote, “An engine running without heat rejection would allow an over unity machine to be built. That violates the law of conservation of energy, and all of physics would be wrong.” Bullshit. Twice over. There’s no “over-unity” represented in converting heat to power. A “cold-hole” engine (i...
by Bumpkin
Tue Jun 20, 2023 8:14 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Stephenz's work
Replies: 58
Views: 10525

Re: Stephenz's work

Have you looked at open-cell metal foam? If it wasn’t for the cost I’d have already checked it out myself. Plus the worry of melting what I consider the most desirable aluminum version — says it’s good for 1000 f though. But there are other metals available. https://ergaerospace.com/metal-foam-mater...
by Bumpkin
Sat Jun 10, 2023 5:38 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Portable generator to Ringbom converstion
Replies: 32
Views: 8462

Re: Portable generator to Ringbom converstion

I’m still pursuing making my Ringbom engine a Beta, but some realities force consideration of a Gamma, wherein the connecting tube could be a length of automotive heater hose. I was mostly interested in simple connection and isolating engine vibration from the heater. I don’t know if it would surviv...
by Bumpkin
Sat Jun 10, 2023 9:18 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: if stirling engine is driven as reversed, does it work as cooler?
Replies: 94
Views: 48247

Re: if stirling engine is driven as reversed, does it work as cooler?

Yes those engines and others would pump heat if powered. It is not “backwards” though. The direction of the flow is the same whether it is pumped or pumping — like a water turbine, for instance. Long ago I got a similar question answered by forum member Ian: “As a stirling engine rotates, it it extr...
by Bumpkin
Sun Jun 04, 2023 12:13 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Tom is right, no heat sink req'd
Replies: 39
Views: 8269

Re: Tom is right, no heat sink req'd

Sorry to respond late to a post way back-thread; It’s my busy time. Anyway, for Tom and your response to my supposition that if you don’t need to remove heat externally because it’s removed internally as energy conversion, then ambient power is possible: All heat engines are heat-difference engines;...
by Bumpkin
Thu Jun 01, 2023 9:10 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Tom is right, no heat sink req'd
Replies: 39
Views: 8269

Re: Tom is right, no heat sink req'd

If true, it logically leads to an ambient powered engine, where the only exhaust is”cold.” I’ve never thought that was impossible; and have been down some of those rabbit-holes myself. I sure wouldn’t discourage others from sifting through those same weeds, or even looking in whole new fields. It wo...