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UPS has recently started using pneumatic
drives to start their vehicles from a stop
because the pneumatic drive is far more
efficient at overcoming the friction from
a
start. After the vehicles are moving, the
ICE takes over.
I propose an engine based on a
pressurized fuel so that the
need for
additional pneumatic cylinders is
eliminated.
The Propane would need to be
depressurized before use in an ICE
engine,
so why not have it release through a
pneumatic motor to drive the startup
mechanism, slightly pressurizing a
second
staging tank, which feeds the ICE.
I'm not proposing this for use in cars, but
perhaps for small home generators and
power backups. The pneumatic engine
could get a flywheel going and then the
ICE could burn the propane to rev it up
to
speed once static friction is no longer a
concern.
[marked-for-engineering] : does this
already exist in propane or AutoGas
engines? Does it seem feasible?
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My last 2 ideas have gone completely
uncommented. Have I offended the HB
gods? |
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well, If you add an additional pneumatic
drive system in an engine, you have to add
an additional cylinder for the pressurized
fluid. |
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Does it have to be propane? |
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no, any compressible, combustible fluid
would work. I was trying to think of an
alternative, but wasn't sure of any. |
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Why just for starting? Why not use the expanding gas to add torque to the running engine? This'd probably work best in a hybrid arrangement, though. [+] |
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PS: Other gasses: Hydrogen, Natural Gas. |
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hmmmm.... propane flywheels you say!? |
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Presumably, the UPS trucks use the hydraulic sytem already installed for the brakes, steering, gears. Anyway, I don't see how it would use a cylinder (I am reminded of [Normzone]'s comment about punting a vehicle along). I would imagine the system uses a turbine. |
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Isn't an ICE pressurized anyway? Aren't most Propane engines 2 strokes for that reason? |
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If you were using a (yes, I'm going to say it) Stirling engine then I can see the advantage of using the pressure, as the engine doesn't make use of it. You could also use the expanded gas to help chill the cold side. Hmm, that might be ideaworthy. |
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//Why not use the expanding gas to
add torque to the running engine// |
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Well, It kind of is, I just didnt make it
that clear in the body. The fuel (not
necessarily propane) releases through
the pneumatic motor into a staging
tank before it reaches the ICE. This will
still be happening after the ICE kicks in. |
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//Isn't an ICE pressurized anyway?
Aren't most Propane engines 2 strokes
for that reason? // |
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I have no idea, I couldn't find a
schematic of a propane engine to see
how it worked. From what I found most
"propane engines" actually run on
Liquified Petroleum Gas (LPG) also
called "AutoGas" which is a mixture of
propane and butane which has a higher
energy rating per liter (nearly double
that of its constituents). I said propane
referring (unknowingly at the time) to
this technology which does already exist
since many vehicles in my neck of the
woods say "Propane Powered" on them. |
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//hmmmm.... propane flywheels you
say!?
// |
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Is that a good thing or a bad thing? |
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//Presumably, the UPS trucks use the
hydraulic sytem already installed for the
brakes, steering, gears. // |
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Understood, but as I stated, this isn't
intended for use in a car, so those
systems would not already be in place. |
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// I don't see how it would use a cylinder (I am reminded of [Normzone]'s comment about punting a vehicle along). I would imagine the system uses a turbine.// |
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Actually I imagine it's directly injected into the cylinder. Large diesel engines <for powerstations or ships> pretty much all use air-start, as it's far better suited. As said, air starts are better at overcoming static friction, and also allow rather precise "throttling". |
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For instance, the 6 large MAN diesel engines our little powerstation up here are air-started. With 400PSI air running through a 4" main, no less. |
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The UPS vehicles may simply use a belt-driven compressor to charge a small tank for starting. I imagine they are interested more in reducing wear at startup, especially with frequent start/stop cycles, than in fuel efficiency. |
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For instance, when aggregating machine run-hours to determine maintenance intervals, likely wear, etc it's common to equate a start or stop event with upwards of 10 run-hours. Often even more. E-stops <crash stops, like a hot-stall or trip from lube failure> can often go as high as 50-100 run-hours. |
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I'd want to wrap the A/C's condenser coil around the propane tank, too - it could conceivably even eliminate the A/C if the boil-off rate is right, then everything could be done with a plate heat exchanger and a pump, way less power-hungry. |
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Huzzah for zombie ideas back from the
dead! |
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//For instance, the 6 large MAN diesel
engines our little powerstation up here
are air-started. With 400PSI air running
through a 4" main, no less.
// |
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So those use separate air supply to get
them started? What's the PSI in a tank
of propane? |
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