Search found 79 matches

by Alfista
Sun Feb 18, 2018 8:45 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Making a stirling engine 5 kw generator
Replies: 8
Views: 278

BTU of common fuels per pound

In researching this question, not all researchers come up with exactly the same figures. Please forgive any "errors" in the collected information. It is only meant as a general guide. BTU per pound of some common fuels Hydrogen 52,290 BTU per pound Acetylene 21,850 Propane 21,660 Gasoline...
by Alfista
Wed Feb 14, 2018 10:17 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: New flame eater with homemade gear
Replies: 8
Views: 209

Re: New flame eater with homemade gear

Wonderful job Thanh-Cuibap ! on the successful gear and the great running engine !

Wayne
by Alfista
Tue Feb 13, 2018 1:16 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Expansion on the hot end
Replies: 4
Views: 127

Re: Expansion on the hot end

Brass would be better than aluminum.
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: 127

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: 8
Views: 211

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: 278

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 w...
by Alfista
Sun Feb 04, 2018 7:33 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Temperature/preessure change while running?
Replies: 8
Views: 211

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: 366

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: 366

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: 366

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: 325

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: 325

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: 293

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: 418

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: 418

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.

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