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Pneumatic Propane Hybrid Engine

Use the Pneumatic pressure release from the propane to drive a starter motor
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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?

bleh, Oct 16 2007

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       My last 2 ideas have gone completely uncommented. Have I offended the HB gods?
bleh, Oct 16 2007
  

       well, If you add an additional pneumatic drive system in an engine, you have to add an additional cylinder for the pressurized fluid.
bleh, Oct 17 2007
  

       Does it have to be propane?
BJS, Oct 17 2007
  

       no, any compressible, combustible fluid would work. I was trying to think of an alternative, but wasn't sure of any.
bleh, Oct 17 2007
  

       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. [+]   

       PS: Other gasses: Hydrogen, Natural Gas.
RunnerPack, Oct 17 2007
  

       hmmmm.... propane flywheels you say!?
quantum_flux, Oct 17 2007
  

       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.   

       Isn't an ICE pressurized anyway? Aren't most Propane engines 2 strokes for that reason?   

       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.
marklar, Oct 17 2007
  

       [bleh][+]
the dog's breakfast, Oct 17 2007
  

       //Why not use the expanding gas to add torque to the running engine//   

       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.   

       //Isn't an ICE pressurized anyway? Aren't most Propane engines 2 strokes for that reason? //   

       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.   

       //hmmmm.... propane flywheels you say!? //   

       Is that a good thing or a bad thing?   

       //Presumably, the UPS trucks use the hydraulic sytem already installed for the brakes, steering, gears. //   

       Understood, but as I stated, this isn't intended for use in a car, so those systems would not already be in place.
bleh, Oct 17 2007
  

       // 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.//   

       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".   

       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.   

       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.   

       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.
Custardguts, Mar 26 2008
  

       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.
elhigh, Mar 28 2008
  

       Huzzah for zombie ideas back from the dead!   

       //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. //   

       So those use separate air supply to get them started? What's the PSI in a tank of propane?
bleh, Mar 29 2008
  
      
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