[opendtv] Off topic: Iris engine
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 8 Jun 2010 19:01:48 -0500
This new idea for an internal combustion engine is interesting, but the
explanation is basically wrong.
http://www.irisengine.com/6901/index.html
Think of a piston engine, where not the piston, but rather the cylinder walls,
move out with each spark ignition. Would it NECESSARILY be more effcient than
having the piston move and not the cylinder walls, like a standard puiston
engine?
In theory, no. In practice, *probably* yes, because the greater area expanding
out will keep most of the engine's internal surface area cooler (gas cools as
it expands). So you don't need as powerful a cooling system to keep the metal
from deforming, which creates less waste heat.
But other practical considerations also exist. The expanding walls are called
"chordons." The chordons have to create as gas-tight a combustion chamber as
possible. With piston engines, you just stack up rings until you're satisfied
that only small amounts of gases blow by. How about these "chordons? Looks like
a narrow surface that does the rubbing, sort of like a Wankel. I'm dubious
about the huge gains compared with piston engines.
Also, check out all those crank shafts you need. One for each chordon. That
can't be good either, in terms of friction losses.
Their explanation only addresses the "working area" of the engine. They state,
"Surfaces exposed to combusting gases in an engine can react either
productively, by moving, or wastefully, by heating." I don't buy that
explanation. If a surface heats, but that heat is allowed to stay put, you
don't waste anything. So what they really mean is, a piston engine would need
to be made of more expensive materials to equal the efficiency of this Iris
engine. Could be. And the counter argument is, let's not forget to obsess over
the sealing surfaces and parasitic losses!
Bert
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