Search found 91 matches

by Alfista
Mon Feb 12, 2018 7:34 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Expansion on the hot end
Replies: 4
Views: 2419

Expansion is an issue

AnonAustria, expansion is definitely a problem. For this reason, a cast iron piston with a cast iron cylinder is a popular combination. Failing that, an undersized aluminum piston with rings of some kind may be in order. If I were building it with an aluminum piston, I would make cast iron rings. I...
by Alfista
Tue Feb 06, 2018 7:07 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Temperature/preessure change while running?
Replies: 11
Views: 4718

larger flywheel

I agree in essence with all of Ian's comments. I would like to add that a better alternative to gearing up would be to make a larger diameter flywheel instead of a heavier one. Gearing up will add friction, that is certain and as such would be a better choice if the source of power were very high i...
by Alfista
Mon Feb 05, 2018 7:52 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Making a stirling engine 5 kw generator
Replies: 8
Views: 5247

Re: Making a stirling engine 5 kw generator

A 12 inch cylinder and 13.5 inch stroke running at 100 rpm should get you pretty close to that figure. Ivo Kolin in his book on heat engines discusses in some detail an engine of Ericsson : bore: 10.25"+14"; stroke : 18", hp: 5 (1833), an alpha as I recall. It had interesting valve work and a very ...
by Alfista
Sun Feb 04, 2018 7:33 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Temperature/preessure change while running?
Replies: 11
Views: 4718

formula

The formula is (T1-T2) / T2 = Pressure in bars. Dividing the result by 2 will probably give you a more realistic number :÷(

Think 2 - 5 psi. T is in kelvin. T1 is the high temperature. T2 the low
by Alfista
Wed Jan 24, 2018 8:00 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Piston rings, O-rings or what?
Replies: 11
Views: 3807

Great Photos

Great photos Ian ! Thank you for posting those !

Wayne
by Alfista
Mon Jan 22, 2018 2:25 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Piston rings, O-rings or what?
Replies: 11
Views: 3807

rings for a 4" piston

I would suggest a lightweight, aluminum piston with 2 rings per piston, each ring .188" to .25" in width. That way, you can also reduce the diameter of the piston and avoid some friction along the length of the piston. If your cylinder is cast iron, use cast iron rings.

by Alfista
Mon Jan 22, 2018 9:07 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Piston rings, O-rings or what?
Replies: 11
Views: 3807

Re: Piston rings, O-rings or what?


Rizzo, among others, writes about using o-rings. Cast iron rings can be an excellent choice in larger engines. Pfte is an excellent choice for making rings but may wear more quickly than some other materials. Rings are probably not desirable in smaller sizes.



by Alfista
Sun Jan 21, 2018 11:21 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: How to create a stirling cold cycle?
Replies: 8
Views: 3574

Re: How to create a stirling cold cycle?

Wellington, If you drive a gamma engine in the direction of normal rotation, with the displacer leading by 90 degrees of crank rotation, then the normally hot end of the displacer will become colder. In an alpha engine, if you drive the engine in the direction of the one piston leading the other by...
by Alfista
Sat Jan 20, 2018 9:33 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: How to create a stirling cold cycle?
Replies: 8
Views: 3574

Re: How to create a stirling cold cycle?


If you drive the engine in the forward direction, the displacer will drop in temperature. According to Sier, it was first described by William Thomson (1847).

by Alfista
Wed Jan 17, 2018 11:49 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Horse power figures of some historic engines
Replies: 3
Views: 3093

Horse power figures of some historic engines

Here are some figures for some historic engines by various makers. Often, the information is incomplete, some list stroke or rpm, others do not, but on the whole, it gives a good, general idea of power production. I would assume that most of these figures refer to INDICATED HORSE POWER. Ericsson bo...
by Alfista
Mon Jan 08, 2018 8:16 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Silver soldering stainless steel hot end
Replies: 12
Views: 4160

Re: Silver soldering stainless steel hot end

have you ever known a stirling engine to explode? Thinking about it i guess they can be dangerous like steam engines. Never thought about stirlings like that. I guess i should be equally cautious like with steam engines. Just been running my mamod steam engine. They are such a joy to run. Wellingto...
by Alfista
Fri Jan 05, 2018 7:35 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Silver soldering stainless steel hot end
Replies: 12
Views: 4160

Re: Silver soldering stainless steel hot end


Wellington, in my opinion it should. I also assume that you intend a silver brazing wire like Harris Safety Silv 45 or something similar. In operation, you should not allow the engine to stall indefinitely under high heat.
by Alfista
Thu Jan 04, 2018 9:51 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Stirling engines with an internal spring question
Replies: 16
Views: 5788

Wagstir and Martini

Wellington, thank you very much for your compliment on the large Stirling engine ! I can suggest two very interesting designs : the Wagstir "Solarsimpleton" engine and the Martini "Stirling Cycle Amplifying Machine" aka the "Martini Displacer". These can be found in the Sier "Hot Air Caloric and St...
by Alfista
Thu Jan 04, 2018 9:23 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Stirling engines with an internal spring question
Replies: 16
Views: 5788

Re: Stirling engines with an internal spring question

Wellington, it seems that you are describing the Ringbom or a free displacer or free piston engine; or am I missing something ? Perhaps I have not understood you. You could look at the designs of Chipperfield, Martini or Beal. Senft has a nice book on miniature Ringbom engines which may be of inter...
by Alfista
Wed Jan 03, 2018 8:41 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Open crank horizontal engine conversion to Stirling cycle.
Replies: 8
Views: 2883

better to start from scratch

At the risk of being seen as a heretic, I would say, don't do it. It sounds like a nice, old engine worth restoring as a gasoline engine. It may be worth watching the unsuccessful attempt of the conversion of an air compressor by Dan Rojas on the Greenpowerscience youtube channel as you would face ...