Search found 131 matches

by Bumpkin
Sat Mar 09, 2019 1:27 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: How can I calculate engine dimentions for example, cylinder volume, diameter and the overall size of the engine>
Replies: 6
Views: 859

Re: How can I calculate engine dimentions for example, cylinder volume, diameter and the overall size of the engine>

I could have dropped a few zeros, but just for kicks I put a pencil to it. A VERY efficient Stirling could at max get 200 kw power from a 500 kw source. For a starting point, and only as an example; assuming a very efficient engine, with a hot end at 600 C and a cool end at 100 C - running 1000 rpm ...
by Bumpkin
Thu Jan 31, 2019 11:18 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: What type of Stirling Engine
Replies: 7
Views: 1172

Re: What type of Stirling Engine

Hello Mac. Your concept sounds very much like the solar project at Tamera. Their engine is a large roll-sock type Beta, suitable for mid to low temp differences. They used oil for thermal storage. I don't know if they're still working on the design. https://www.youtube.com/watch?v=SMMELH7CSNE Bumpkin
by Bumpkin
Thu Jan 03, 2019 11:08 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Burnt pancake displacer (carbon foam)
Replies: 8
Views: 3184

Re: Burnt pancake displacer (carbon foam)

I know this is an old thread but here's another recipe that makes me wonder just how far we can take easy home cookery towards producing useful Stirling components:

Bumpkin
by Bumpkin
Tue Nov 27, 2018 8:57 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Thanks boydhouse
Replies: 2
Views: 891

Thanks boydhouse

I've been posting a bit and lurking a lot for a few years and I want you to know how I respect the the time you put in here. (Including cleaning up idiot adverts and such) A certain kind of mindset (weirdness?) brings us here and it's a blessing to have a community.

Bumpkin
by Bumpkin
Fri Aug 03, 2018 6:02 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Gamma type cylinder and displacer
Replies: 24
Views: 4924

Re: Gamma type cylinder and displacer

Looks like it's been worked out, but if we would say SWEPT volume for the ratio of displacer to power, it might save some confusion.
:smile:
Bumpkin
by Bumpkin
Sun Jun 10, 2018 11:02 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: the volume ratio between displacer cylinder and power cylinder
Replies: 4
Views: 1755

Re: the volume ratio between displacer cylinder and power cylinder

Hi Oscarmike. Here's a link to something about the math stuff. The relevant stuff is towards the top.

http://www.spragueriver.com/index.php/bumpkin-tech

Bumpkin
by Bumpkin
Wed Mar 21, 2018 11:27 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Large LTD Diaphragm Gamma Stirling Questions
Replies: 19
Views: 5400

Re: Large LTD Diaphragm Gamma Stirling Questions

Hi playludesc Development of these engines is more important to me than the modeling, so know I mean this respectfully. You can always copy other engines, but for unique circumstances and applications you should learn the basic science behind the ratios. You could Google the Ideal gas law or Boyle's...
by Bumpkin
Fri Dec 29, 2017 11:24 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: small wood gassifier generator
Replies: 11
Views: 3679

Re: small wood gassifier generator

Hey Ian, I always wondered how a prony brake could be consistent enough to get a good reading. Now I see the springs and it's clear. Thanks. Alfista, I watched the video. I would think it might be easier to test your engine's power by finding the biggest load (light bulbs?) it will run up to voltage...
by Bumpkin
Sun Dec 17, 2017 10:33 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: small wood gassifier generator
Replies: 11
Views: 3679

Re: small wood gassifier generator

The trouble, as I see it, with small scale wood gasification is it tends to take a lot more tending than just a basic wood stove. Also if it's done inside a living space there's always some degree of danger from carbon monoxide - stuff happens. There are off-grid folks who use wood-gas to run a more...
by Bumpkin
Tue Nov 21, 2017 9:56 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Double-acting solar Gamma, twin rotary displacers
Replies: 4
Views: 2419

Re: Double-acting solar Gamma, twin rotary displacers

Nearly 40 years off-grid here myself, and a big Stirling fan, but it's hard to compete with modern P.V. system prices, even including batteries wires controllers and inverters. A solar Stirling combination with a VAWT is intriguing. The big problem with Stirling rotary displacers is that they move a...
by Bumpkin
Fri Mar 10, 2017 11:21 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Heater & Regenerator Design
Replies: 60
Views: 24417

Re: Heater & Regenerator Design

I like your crankshaft design. It always seems funny when people turn the crank back to the main center before swinging it back out 90 degrees, even without the purpose of providing another main bearing. That said; is there a key or something to register the clamping of the second throw for accurate...
by Bumpkin
Mon Feb 27, 2017 12:16 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Low temperature differential (LTD) alpha designs?
Replies: 4
Views: 3490

Re: Low temperature differential (LTD) alpha designs?

I'm not a fan of Alphas except for high temp versions, and even then they generally use heat sources that might be better and more efficiently spent elsewhere. But that said; you can lower the peak volume ratio to where it works with lower temps, with variable volume. The weight of a few inches of w...
by Bumpkin
Mon Feb 20, 2017 10:41 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Pressurization
Replies: 20
Views: 9558

Re: Pressurization

Aviator, I forgot to mention another problem with a pressure imbalance above and below the piston. (beyond the normal power pulses) There is a greatly increased rod and main bearing load. I bumped into that while trying to think up a pressurized diaphragm type engine. A set of two opposed and linked...
by Bumpkin
Sun Feb 19, 2017 12:31 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Pressurization
Replies: 20
Views: 9558

Re: Pressurization

Hi Pete. Neat that you saw the Jim Dandy six operating. 15 or 20 minute feeding intervals wouldn't be too bad if you were right there working in the shop anyway. Burning home-made fuel beats buying pellets any day. Aviator, you are probably a better machinist than me, but I'd still bet an open-crank...
by Bumpkin
Sat Feb 18, 2017 8:44 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Heater & Regenerator Design
Replies: 60
Views: 24417

Re: Heater & Regenerator Design

"Looking to run at 15bar fairly quickly but then maybe more." - You probably already know, but remember not to mix air and oil at high pressures/temperatures. From wikipedia - "At high temperatures and pressures, the oxygen in air-pressurized crankcases, or in the working gas of hot air engines, can...