h a l f b a k e r yYou gonna finish that?
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It has come to my attention that the days of the internal
combustion engine are numbered. The number is more
than say,three, but it's not forty one million nine hundred
thousand and eleven. The electric motor, being a British
invention, is finally coming to be appreciated by the wider
world
as a superior way of creating movement. It's simple,
elegant, and goes about its business with the calm
authority of an object that really knows what it's doing. As
a contrasting example, I submit the Harley Davidson V-twin
motorcycle engine. Essentially this is some low-grade pig
iron that produces a little useful rotation before the
combination of wasted heat and vibration destroys the
structurally-critical chrome plating.
People still buy these things however, not with their
brains, but because they're high on a mix of gasoline vapor,
expensive marketing and nostalgia. I fear the electric
motor will never provide the same experience so the
lumpen V twin may continue unchanged for another 97
years until it is outlawed and another way to scratch that
itch must be found.
How about a new market? The humble clothes dryer is ripe
for some Harley style. Right now, the typical dryer uses an
electric motor to spin a drum, a fan to blow air through
the drum and because the motor and fan are so efficient, a
heating element to heat the air. That's dreadful. Lets
replace the electric motor with a 750cc Harley V twin.
Now, a normal dryer gets to about 5 kW. The Harley
engine idles at around 10kW at the output shaft, that's at
least 10x too much power. BUT the horrifically inefficient
engine is producing around 15kW heat. Now, just route the
air past the air-cooled engine into the drum and you have
solved the heating and rotation requirements of the dryer.
In fact it's over spec. No problem, we can probably put a
generator on the shaft too, get some useful electricity,
feed it back into the grid. Best of all, it can probably be
made to run on natural gas, like a gas dryer only instead of
just burning the gas to make heat, you make it do all the
physical work first, and use the same amount of heat
anyway.
And who wouldn't want a sweet V-twin idling in their
basement for hours at a time?
Harley 750 twin dyno graph
http://www.cyclewor...-on-cw-dynojet-dyno
[bs0u0155, Jun 22 2016]
[link]
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" sweet V-twin idling in their basement for hours at a time " |
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You must be kidding, referring to that irregular plodding as "idling" - but at least the appliances would have a broad dealer support network, lots of aftermarket accessories, and you could identify the users by the colorful clothing. |
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I'm sure various manufacturers will all get in on the
action when they realize how many dryers are sold
compared to motorbikes. A Triumph triple for me, or
possibly one of the desmodromic Ducati engines from the
90s. |
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You wouldn't be the first, although watch out if a cam
chain goes. |
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// The Harley engine idles at around 10kW at the output shaft, // |
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Harley starters are about 1.5kW - and that's enough to overcome inertia, cylinder compression, and friction in a cold engine. Once the engine is at working temerature, with the oil a little thinner and some clearances increased, 2kW should keep it ticking over. |
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Even with th gears in neutral and the clutch in, that's only going to add 10-15%. |
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If the engine is developing more energy at the output shaft than required by installation losses, its speed will increase from idle. Durrrr... |
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So, by definition, an idling engine isn't producing any output power, otherwise it wouldn't be idling. Loading an idling engine will just stall it. |
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So where does the 10kW come from ? Show your working. Write on both sides of the paper, in ink. You may open your question book now. |
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Re <link>, still not convinced. Those graphs only start at around 2000 rpm - idle speed is a lot lower than that, 1000 rpm or even less. |
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I didn't realize Anyos Jedlik was British. Maybe Britain
thought they ruled Hungary at the time? |
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//Are you sure about that? // |
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I just took the bottom end of the dyno graph <link> and
converted it to kW. Idling isn't exactly as you describe, even
with constant fuel and air input there's a little energy to be
had. In fact look into full and part load efficiency. |
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We have, and it's no-load efficiency which is the issue; it's very poor. |
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It's not possible just to extrapolate those graphs to the point where the process is only just self-sustaining. |
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Whatever happens, the engine has to move the
drum, that's a tiny load, 1/3rd of a horsepower or
so. I mentioned a supplementary generator, make
that 5kW, then maybe add an automotive style A/C
compressor arrangement and use it to condense
the dryer exhaust. Call that another 5kW. Then just
run the engine at whatever level of throttle is
needed. The dryer is arranged to intake the air past
all the air cooling fins and possibly some form of
exhaust heat exchanger. Efficiency doesn't matter
much, you're burning domestic natural gas to make
heat in a slightly more convoluted way than a
regular gas dryer... only you don't need electricity
anymore. |
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And you get to change the oil and gap the spark
plugs on more things.... I think that's good. |
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//a British invention// Sp.: "English". |
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Would a jet engine not work better? |
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Automotive a/c units have horrid torque loads at
low rpms and definitely play with idling behavior. |
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Gee Your Clothes Smell Like Gasoline |
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Follow on to: "Gee your Hair Smells Terrific" |
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YOUR underwear smells like JP4, Max ? |
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