Posted by harry k on December 19, 2011, 9:06 pm
As to efficiency, the ice sucks but noone has come up with better
yet. Electrics may do it. Sterling for sure won't due to one basic
law of thermo.
Every time to convert energy from one form to another you lose some.
ICE does it onece, Sterling does it twice.
Posted by Morris Dovey on December 20, 2011, 4:56 pm
On 12/19/11 3:06 PM, harry k wrote:
I may have missed something, but I'm seeing
ICE: (hydrocarbon+air) chemical -> thermal -> mechanical -> electrical
and I'm working on
Stirling: (Ni+H) nuclear -> thermal -> mechanical -> electrical
both of which appear to involve three conversions.
It's difficult for me to make any meaningful efficiency comparisons
between chemical and nuclear processes - they're just too different -
but I like that 1.75 ounces of nickel was enough to produce ~5kW (of
heat) round the clock for six months in a prototype reactor.
AFAICT, ICE and conventional Stirlings both bleed thermal energy
absolutely everywhere. "Incidental" thermal losses (those over and above
the energy intentionally discharged as part of their Carnot cycle) in
both conventional Stirlings and ICE constitute a major efficiency problem.
There are 5 (maybe 6) things that stoke my enthusiasm for the Stirling
I'm working on: (1) The only moving part is gas inside a sealed
cylinder, (2) there are two power 'strokes' in every cycle to improve
efficiency, (3) the only by-product of heat production is copper metal,
(4) the generator, with the reactor tucked inside, should be small
enough that a half-dozen of them will fit into an ordinary attache case,
(5) it appears possible to eliminate virtually all of those incidental
losses, and (maybe 6th) by using a nuclear reaction, there may be enough
power available to chemically produce the hydrogen fuel component on the
fly from ordinary water without significantly reducing the net output.
There's a fair amount of R&D to be done, but the good news is that as
soon as one of these things can be demonstrated, there'll probably be a
lot of folks interested in improving on it, and some of 'em will
Posted by harry k on December 21, 2011, 3:32 am
ICE and Stirling are extremely lossy, kinda oxymoronic toeven discuss
"eficiency :). but so far the ICE seems to be the only easonable game
The conversion as I see it is: (ignoring the final step of what you
do with the mechanical action since that is the same fro both).
ICE: chemical - thermo - mechanical,
Stirling: chemical or nuclear - thermo - working fluid - mechanical.
I add he extra step there as you do not go direct from thermo to
You have a good point about the "two stroke" advantage.
Posted by Morris Dovey on December 21, 2011, 9:19 am
On 12/20/11 9:32 PM, harry k wrote:
Actually (I probably didn't present it very well) I do. In both engine
types the heat is applied to a gas - air in the ICE and supercritical
water in my Stirling. In both engines the mechanical energy is produced
by a heat-induced pressure differential in the working gas.
In the ICE, this pressure drives the piston toward the crankshaft and
then the heated air is discarded on the following upstroke and a cooling
system is used to continuously remove heat from the engine to protect it
from overheating. All this is followed by a purely overhead piston cycle
to draw in fresh, cool combustion air and compress it for the next cycle.
In my Stirling design, the gas /is/ the piston, and (if the hot head and
flow-restrictors are completely insulated) the heat energy released and
the mechanical energy produced should be extremely close to the
(theoretical) Carnot limit. The gas oscillates between the two ends of
the sealed cylinder in such a way that there is a 'power stroke' with
each half-cycle (in other words, unlike the traditional Stirling and the
ICE, the piston is powered first in one direction and then powered in
the other) with no non-power-producing motion.
Removing the mechanical -> electrical conversion masks one of the
advantages of this Stirling generator: the oscillating gas doubles as
the primary (ionic) charge carrier for the MHD heads integrated into the
flow-restrictors. With this approach, the generator isn't a separate
device to be built and coupled to the engine, but an integral part of
the engine itself.
A side benefit to this Stirling design is that there aren't any solid
moving parts to produce friction and/or wear out. These engines should
have a /very/ long service life - /much/ longer than the electric motors
But they aren't today, so the ICE with all its warts is what we have to
work with for the time being...
Posted by News on December 21, 2011, 1:59 pm
Only because of massive vested interest in the silly Victorian piston