Eliminate the displacer?

Discussion on Stirling or "hot air" engines (all types)
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Bumpkin
Posts: 280
Joined: Fri Mar 02, 2012 1:42 pm

Eliminate the displacer?

Post by Bumpkin »

Hi folks. Some recent down-time left me with too much thinking and too little doing. Here's part of the residue, in case it could be useful to someone. For possible critique or discussion there's more stuff and a contact address at my page on wood stove co-generation:
http://spragueriver.com/index.php/bumpkin-tech

"That wonderful radiant heat from a wood stove has little affect on air until it heats a solid, which then conducts heat to the air. And even with forced convection, heat exchange from a solid to air is slow beyond the boundary layer. So it's difficult to rapidly move heat in and out of a Stirling engine with simple heaters and coolers; but in the forced flow between the two, a simple fine-mesh regenerator breaks the boundary layer and exchanges heat very effectively. Perhaps we could attach the job of moving heat in and out of the engine to the regenerator. If instead of a displacer, we reciprocate a thin big-bore regenerator in a matching chamber, it could radiantly exchange heat with the chamber ends and pass the exchange to the air. This "pancake-style" regenerator might also be the best compromise between flow and dead-space."

- Yes I know this is basically the same as some existing low temperature engines with regenerative displacers, but I think it would be better to remove the displacer entirely and maximize the regenerator's radiant exposure. What do you think?

Bumpkin
Tom Booth
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Joined: Tue Nov 07, 2006 2:03 am
Location: Fort Plain New York USA
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Re: Eliminate the displacer?

Post by Tom Booth »

I've often thought that a "displacer" doesn't really do anything but create some turbulence... which alternately helps to bring more air into contact with the hot and cold surfaces. Something that agitates the air while providing greater surface area might very well make for some improvement IMO.
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