Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

orbywan · 01-11-2012, 10:48 PM

Thanks slowmover. I haven't gotten far enough with the aero mods yet to dive into solar. I do a lot of camping in the Arizona mountains so it is high on the list.
OK, aerohead told me about a guy who built a diesel pusher trailer to assist in locomotion of an electric VW. That's pretty far out there. You can read more about it at http://www.mrsharkey.com/lpg.htm. Sorry, I'm at a show in Calif and don't have my notes on how to make an uptown link to that site so you can just click on it. Here's an excerpt:

"Introducing LPG gas into the combustion air intake of a diesel engine acts as an accelerant, promoting the even burning of the diesel fuel, and more complete combustion, resulting in more power being produced. Many web pages and forum posts will call LPG a "catalyst" but this is not correct, as LPG creates no change in the molecular makeup of either the air or the diesel fuel.

Propane by itself resists self-ignition inside a diesel-fuel compression-ignition engine due to it's high flash point and narrow fuel-to-air ratio. During the compression stroke, the air/LPG mixture is compressed and the temperature is raised to about 400°C, not enough to ignite the LPG, which has an ignition temperature of about 500°C. In the small concentrations that LPG fumigation uses, the LPG mixture is not rich enough to be overly flammable and is more difficult to ignite. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self-ignites (diesel ignites at about 385°C.), and causes the LPG to burn as well. Since the LPG is in mixture with the air, the flame front from the diesel spreads more quickly, and more completely, including igniting the air/fuel mixture which is in contact with the cylinder walls, which are cool in comparison to the super-heated air inside the combustion chamber. Much of the cleaner burning of the fuel is attributed to this ignition against the "cooler" components of the engine, and accounts for raising the percentage of combustion from a typical 75% for a well-tuned diesel engine running on pure diesel fuel alone, to 85-90% with the addition of LPG. Obviously, this more complete combustion also gives a nice boost in power, with an accompanying increase in fuel economy and reduction of pollutants."

I want all that to be true because it has good implications for my project, but I'm curious if anyone has any documented info that supports or defeats this?

01-11-2012, 10:48 PM	#158 (permalink)
orbywan EcoModding Apprentice Join Date: Jul 2010 Location: Tucson, AZ Posts: 245 Thanks: 111 Thanked 163 Times in 63 Posts	Thanks slowmover. I haven't gotten far enough with the aero mods yet to dive into solar. I do a lot of camping in the Arizona mountains so it is high on the list. OK, aerohead told me about a guy who built a diesel pusher trailer to assist in locomotion of an electric VW. That's pretty far out there. You can read more about it at http://www.mrsharkey.com/lpg.htm. Sorry, I'm at a show in Calif and don't have my notes on how to make an uptown link to that site so you can just click on it. Here's an excerpt: "Introducing LPG gas into the combustion air intake of a diesel engine acts as an accelerant, promoting the even burning of the diesel fuel, and more complete combustion, resulting in more power being produced. Many web pages and forum posts will call LPG a "catalyst" but this is not correct, as LPG creates no change in the molecular makeup of either the air or the diesel fuel. Propane by itself resists self-ignition inside a diesel-fuel compression-ignition engine due to it's high flash point and narrow fuel-to-air ratio. During the compression stroke, the air/LPG mixture is compressed and the temperature is raised to about 400°C, not enough to ignite the LPG, which has an ignition temperature of about 500°C. In the small concentrations that LPG fumigation uses, the LPG mixture is not rich enough to be overly flammable and is more difficult to ignite. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self-ignites (diesel ignites at about 385°C.), and causes the LPG to burn as well. Since the LPG is in mixture with the air, the flame front from the diesel spreads more quickly, and more completely, including igniting the air/fuel mixture which is in contact with the cylinder walls, which are cool in comparison to the super-heated air inside the combustion chamber. Much of the cleaner burning of the fuel is attributed to this ignition against the "cooler" components of the engine, and accounts for raising the percentage of combustion from a typical 75% for a well-tuned diesel engine running on pure diesel fuel alone, to 85-90% with the addition of LPG. Obviously, this more complete combustion also gives a nice boost in power, with an accompanying increase in fuel economy and reduction of pollutants." I want all that to be true because it has good implications for my project, but I'm curious if anyone has any documented info that supports or defeats this?