IS THERE A DIESEL FUEL ALTERNATIVE COMING?

[jonyyuma]

The county schoolbuses in our little state have been burning Cng for some time???l

 

[Sutol]

Safeway supermarkets were running natural gas semi rigs over here ten years ago. They had two big tanks of gas slung at the side if the tractor unit like large fuel tanks.
The range was not as good as diesel trucks but it was one h*ll of a lot cheaper.
Safeway are not in business over here now so dont know what happened to the trucks.

Several other companies were running big rigs on gas at the time as well.
Dont know if they still do as I retired years ago

 

[PoorMansCat]

I believe thats how the Deepwater Horizon explosion occured. The diesels on the deck of the platform ran away on the gasses coming out of the well.

Diesel engines that are in potential explosive environment locations are suppose to have a positive air shutoff system and redundant system! We routinely check these every 250hrs of operaion.

 

[buickanddeere]

Actaully, diesel engines DO NOT require a spark ignition system to run on NG... the compression is high enough int he cylinders that it will compression ignite very easily. We have installed many dual-fuel conversion systems on large modern diesel engines. These engines are used in the drilling and fracing industry. They take advantage of wellhead gas from nearby well-sites to vastly lower the diesel fuel consumption. The technology is already here, its EPA certified and the products are already in use... It might take some time to get the average auto consumer to buy in... but its already here. Personally, I believe the "big 3" need to get off their backsides and start building factory CNG vehicles.... Its cheap, clean, and abundant but most importantly, it here in American soil!.

The NG does not ignite from compression, the engine would suffer detonation as if it was supplied LP above the lower explosive limit.
NG works in diesels with pilot ignition. The injection pump is operating and injects a slow idle metering levels. Power is increased by adding NG to the intake air stream.
Why not burn somebody else's oil and keep our own for when everybody else runs out?

 

[BobRip]

Why not burn somebody else's oil and keep our own for when everybody else runs out?

I suspect we need to try every potential energy source to prepare for the future. Savings some of ours is part of this.

 

[Ilikeurtractor]

The NG does not ignite from compression, the engine would suffer detonation as if it was supplied LP above the lower explosive limit.
NG works in diesels with pilot ignition. The injection pump is operating and injects a slow idle metering levels. Power is increased by adding NG to the intake air stream.
Why not burn somebody else's oil and keep our own for when everybody else runs out?

Thanks for clearing that up - I was wondering about it. Although that brings up another question - what is the performance on diesel fuel vs. NG for the same engine? I'm guessing under NG the power output drops significantly, due to the lower BTU value of NG vs. diesel fuel and also the fact that by adding NG to the intake stream this seems like it would displace some amount of air (oxygen) that can enter the engine and therefore the ability to combust fuel. Any ideas on how much of a hit the engines gives up in power as a percentage figure?

 

[EarPlug]

GMC, Chevrolet Offer Full-Size Bi-Fuel Trucks Using CNG or Gasoline DailyTech - GMC, Chevrolet Offer Full-Size Bi-Fuel Trucks Using CNG or Gasoline

These are actually "conversions" available from the factory. I think Dodge has the same offer.

The conversion tank is placed in the bed of the truck taking up about 3 feet of the cargo area.

Check out www.cngnow.com to see if there are fueling stations near you.

 

[scrappy isb67]

The NG does not ignite from compression, the engine would suffer detonation as if it was supplied LP above the lower explosive limit.
NG works in diesels with pilot ignition. The injection pump is operating and injects a slow idle metering levels. Power is increased by adding NG to the intake air stream.
Why not burn somebody else's oil and keep our own for when everybody else runs out?

NG or any gas type fuel does not require an ignition system to ignite in a diesel. the cylinder temp is high enough to ignite. if the NG is injected in the place of diesel, you cannot have detonation if there is no fuel present. once it is injected, then ignition occurs, JUST LIKE IT WAS RUNNING ON DIESEL. the only difference is timing of injection. Cummins actually sells CNG engines that are basically DIESEL engines with modified timing for cng. diesels can even run on alcohol! most (if not all) of top pulling tractors run alcohol in a DIESEL engine!

 

[Ilikeurtractor]

NG or any gas type fuel does not require an ignition system to ignite in a diesel. the cylinder temp is high enough to ignite. if the NG is injected in the place of diesel, you cannot have detonation if there is no fuel present. once it is injected, then ignition occurs, JUST LIKE IT WAS RUNNING ON DIESEL. the only difference is timing of injection. Cummins actually sells CNG engines that are basically DIESEL engines with modified timing for cng. diesels can even run on alcohol! most (if not all) of top pulling tractors run alcohol in a DIESEL engine!

True. Also note that NG autoignites at roughly double the temperature of diesel fuel (about 1100 deg F vs. 500 deg F). Finding the temperature inside the cylinder for, say, a 20:1 compression ratio is a bit elusive but I found this where you can input parameters for a diesel and see a calculated temperature rise:

The Diesel Engine

According to that page, you should see about 905 deg K which is 1170 deg F, enough to allow it to run. Of course, higher compression ratios will only help this. It looks like the cut-off point is about 17:1 or so based on this page. Neat stuff. It makes sense about the timing also since NG will compress in the injector pump causing a delay in the pressure rise to inject.

 

[buickanddeere]

Forget about running a diesel engine on 100% NG and no spark plugs. Direct injection of NG into the combustion chamber is to prevent power loss due to NG displacing air during the intake stroke.
Pilot injection of diesel to ignite NG is favored due to low cost, easier starting and dual fuel cabability if the NG supply runs out.
Highway diesels running on NG favour the direct injection of NG to maximize HP with the least weight, size/displacement and allows very high turbo boost psi.