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The Artful Bodger
09-27-2012, 05:55 PM
I have an idea to build a 'model' engine to run on barbeque charcoal.

Of course the ideal would be a gas producer and an internal combustion engine but I want to try something more 'primitive' than that. I want to try a charcoal burning 'atmospheric' engine, i.e. a charcoal burning 'flame licker'.

From what I can determine a charcoal fire is much hotter than an alcohol flame and should(?) make for a more powerful engine.

The engine would be a single cylinder engine with a water jacket for cooling, the intake path would be arranged to draw air through the hot charcoal bed and the exhaust would be through a seperate exhaust port.

The engine would not be 'tiny' maybe a 4" bore and 6" stroke, depending on what cast iron drain pipes I can find. I expect there will be enough challenges to get it to run without trying for miniaturisation.

Now for the questions and request for ideas!;)

What can I line the furnace and intake tract with that will withstand the heat of the forced draft charcoal fire?

Any ideas for intake valve material, which can take the heat? I am thinking of a slide valve with an easily replacable cast iron component.

What is the end product of burning charcoal? Just ash and not tars that might gum up the works? I am prosposing to let the ash go right through the engine and out the exhaust but if it runs really well I would consider making a cyclone to go between the furnace and the engine. OK, the engine wont last forever with ash and grit going through it but maybe long enough.

The engine will tend to run faster as increasing rpm draw more air through the furnace so I am thinking of mixing cold air into the intake tract as a means of speed control, any other suggestions?

OK, daft idea that may never come to anything, but maybe.....:rolleyes:

RLWP
09-27-2012, 05:59 PM
I like this idea, although I would go for a hot air engine rather than a flame gulper

But then, I can't get my flame gulper to work, my two hot air engines, even the one made of old cans, worked first time

Richard

The Artful Bodger
09-27-2012, 06:31 PM
Whats your definition for hot air engine?

RLWP
09-27-2012, 06:48 PM
Something with a closed cycle, like a Stirling engine, a Robinson or a Ryder-Ericsson, or something like that

http://www.smokstak.com/gallery/files/1/ryder.jpg

Thinking a little more on this, a closed cycle engine would avoid drawing abrasive materials into the cylinder from the charcoal

Richard

The Artful Bodger
09-27-2012, 09:19 PM
OK Richard, I understand now. My friend Peter made a nice one of those with solid fuel...
http://peterlynnhimself.com/images/Piwakawaka_Engine.jpg

aostling
09-27-2012, 10:00 PM
My friend Peter made a nice one of those with solid fuel...


Your friend's engine looks pretty slick, a water-cooled Beta Stirling: http://en.wikipedia.org/wiki/File:Beta_stirling_animation.gif

It looks like it might be big enough to do some actual work.

Toolguy
09-27-2012, 10:04 PM
That is very cool!! I'd like to get some plans for one of those.

The Artful Bodger
09-27-2012, 10:25 PM
Peter has made a number of engines all about the same size with various variations.

Here is a short video of one in a boat..

http://www.youtube.com/watch?v=ewKeNmXk59A

Peter's home page is at http://peterlynnhimself.com/index.php

TGTool
09-27-2012, 10:48 PM
Among other design considerations, shouldn't the exhaust of a Barbeque engine smell delicious?

JFLingg
09-27-2012, 11:27 PM
Olaf A. Berge (deceased) of Cass Lake, Minnesota, built full-sized engines from original patent drawings, he also displayed and ran these engines. Most were Stirling cycle of the older types. However he did build a "barbecue" engine from patent drawings that worked exactly as described in Artful Bodger's original post. I saw the engine at the Lakehead Harvest Reunion in Esko, MN, That was at least 20 years ago. Where it may be now, I don't know.
He told me that the flyash did cause valve problems, but I don't remember the valve type. Maybe someone who knows how could do a patent search.

JFLingg

The Artful Bodger
09-28-2012, 12:31 AM
Thanks, that is very interesting so at lest there is no hidden law of physics or chemistry which would make my project impossible.

I am hoping that slide valves will be self cleaning, providing there is not 'sticky' gum or whatever in the hot gases coming out the bottom of the furnace.

aostling
09-28-2012, 02:02 AM
Thanks, that is very interesting so at lest there is no hidden law of physics or chemistry which would make my project impossible.


Perhaps not impossible, but a "flame licker" engine doesn't have anything more than a partial vacuum to move the piston. [edit] This is different from a Stirling engine, which has positive pressure moving the piston on the power stroke.

Black Forest
09-28-2012, 02:47 AM
I really like this idea!

EVguru
09-28-2012, 05:34 AM
How about a Manson engine.

It's heat cycle like a Sterling engine, but the cycle is open.

http://www.stirlingengines.org.uk/gifs/man1.jpeg

rowbare
09-28-2012, 02:12 PM
Check these pages. The site and its companion http://www.notechmagazine.com/ are both quite interesting.
http://www.lowtechmagazine.com/2011/11/gas-bag-vehicles.html
http://www.lowtechmagazine.com/2010/01/wood-gas-cars.html
bob