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#3329982 - 04/01/14 07:01 AM Re: Urea injection for diesel [Re: wemay]
ac_tc Offline


Registered: 05/06/08
Posts: 540
Loc: sweden
"you're basically correct. EGR lowers combustion temps (less O2) which lowers NOX formation."

- Here you have whats troblesome with egr.
It lowers combustion temperatures...
-This means that you have to use more fuel since it is the temperature of the expanding gasses thats drives your engine.
Lower the temperature and output will be lower.
Then there are other problems like soot, large egr coolers and the assorted plumbing and valves but these are merely solvable
problems unlike the lower temperature wich have to follow a natural law and to that theres nothing you can do.
_________________________
-98 Dodge Durango 5.9 4*4 HDEO 10w- 40 ci4
-04 PT Cruser GT 10w- 40 HDEO ci4
-Everything else HDEO 10w- 40 ci4/STOU 10w-30/THF

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#3330009 - 04/01/14 07:28 AM Re: Urea injection for diesel [Re: wemay]
TiredTrucker Offline


Registered: 01/04/08
Posts: 1091
Loc: Kellogg, IA
I wouldn't agree that EGR is the best method for reducing NOx. This could have all been handled quite well outside the engine with SCR, either in Urea DEF form or with a cartridge substrate solidified form like has been developed by Amminex. All emissions cleanup could be handled downstream of the diesel engine. The EPA, who has never turned a wrench on an engine, is behind the EGR idea. EGR on gassers is one thing, it is quite another on a diesel. With a diesel you need to have a cooler unit that will cool the exhaust gasses before feeding them to the intake. This puts tremendous loads on the cooling system over an above the engine needs itself. And when one of those coolers blows a leak, just hope you catch it before you need an engine rebuild.

Between the soot loading back into the engine, the required cooling of the EGR gasses, and the reduced combustion efficiency, which in turn increases the level of soot (talk about a dog chasing his tail), there is not one good thing about EGR and diesel engines. It was primarily because of the increased soot generation brought on by EGR that diesel particulate filters were mandated.

I currently am using a '98 EPA certified 2000 model 12.7 Detroit 60 in my 2013 model year truck. This engine has had some nice ECM tuning work done and it generate 550 hp and 1850 torque, and barely even soots anything. The stack tips remain very clean. No EGR and no DPF. That was not the case with my previous Cummins ISX with EGR. The soot loading on that one was tremendous. And along with the lower soot loading of the engine I use now, it puts the other engine to shame in fuel efficiency. I easily get 20-25% better fuel economy.
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#3330034 - 04/01/14 08:00 AM Re: Urea injection for diesel [Re: TiredTrucker]
BMWTurboDzl Offline


Registered: 04/15/10
Posts: 1329
Loc: Atlanta,GA
Originally Posted By: TiredTrucker
I wouldn't agree that EGR is the best method for reducing NOx. This could have all been handled quite well outside the engine with SCR, either in Urea DEF form or with a cartridge substrate solidified form like has been developed by Amminex. All emissions cleanup could be handled downstream of the diesel engine. The EPA, who has never turned a wrench on an engine, is behind the EGR idea. EGR on gassers is one thing, it is quite another on a diesel. With a diesel you need to have a cooler unit that will cool the exhaust gasses before feeding them to the intake. This puts tremendous loads on the cooling system over an above the engine needs itself. And when one of those coolers blows a leak, just hope you catch it before you need an engine rebuild.

Between the soot loading back into the engine, the required cooling of the EGR gasses, and the reduced combustion efficiency, which in turn increases the level of soot (talk about a dog chasing his tail), there is not one good thing about EGR and diesel engines. It was primarily because of the increased soot generation brought on by EGR that diesel particulate filters were mandated.

I currently am using a '98 EPA certified 2000 model 12.7 Detroit 60 in my 2013 model year truck. This engine has had some nice ECM tuning work done and it generate 550 hp and 1850 torque, and barely even soots anything. The stack tips remain very clean. No EGR and no DPF. That was not the case with my previous Cummins ISX with EGR. The soot loading on that one was tremendous. And along with the lower soot loading of the engine I use now, it puts the other engine to shame in fuel efficiency. I easily get 20-25% better fuel economy.


It would be nice to not need EGR. I guess current SCR systems can only convert a certain amount of NOX because I'm sure OEMS would've done away with EGR. Maybe in the not so distant future it will happen.

Interestingly it seems that only passenger cars and light trucks Diesels are likely to have EGR issues whereas OTR trucks do not.
_________________________
'15 435i - Factory fill.
'10 335d (sold)

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#3330187 - 04/01/14 10:37 AM Re: Urea injection for diesel [Re: wemay]
m37charlie Offline


Registered: 06/08/09
Posts: 1143
Loc: Alaska
With EGR my camper wall above and behind the stack used to get soot deposits.
With the EGR cooler in the garage (replaced by a plate) there is no more soot buildup on the camper, or in the air. So I've traded somewhat more NOx for much less soot emission. And no more risk of potential engine-deadly EGR cooler leak (already happened once at 12000 mi, replaced with revised part under warranty).

Charlie
_________________________
05 Unimog U500/Unicat camper/Delvac 1 SHC ACEA E4/E5
09 BMW X5 35d/Delvac1 LE 5W30
01 BMW 325xi M1 0W40
52 Dodge M37/Hercules diesel
79 BJ40 Landcruiser

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#3330550 - 04/01/14 04:59 PM Re: Urea injection for diesel [Re: wemay]
TiredTrucker Offline


Registered: 01/04/08
Posts: 1091
Loc: Kellogg, IA
As to whether the OEM's would have dropped EGR since we have SCR, not so sure. There is a lot of regulatory stuff going on behind the scenes. The OEM's are pretty much at the mercy of what the EPA is going to allow or not allow them to do in meeting emissions requirements.

Could it be to cover for when the DEF might be frozen in the lines before the engine has warmed up and coolant circulated to thaw the DEF? Could be it. But the cartridge that Amminex has had developed for a while now would circumvent that issue.

What I find truly amazing is that Navistar bought into Amminex to the tune of 50% ownership, and has yet to even put one of these on their commercial trucks. Since they got into a mess with the EPA regarding their non use of SCR and trying to meet regs by heavy dosing EGR, they had to finally put on SCR. They could have done the cartridge thing and made many folk's life easier. But they didn't. Go figure.
_________________________
Hey there, VA, what do ya say? How many vets did you kill today?

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#3330609 - 04/01/14 06:34 PM Re: Urea injection for diesel [Re: wemay]
A_Harman Offline


Registered: 10/01/10
Posts: 4374
Loc: Michigan
Navistar adopted the EPA's emissions control technology that relied heavily on EGR, and then found their engines couldn't pass production audit testing. Now they're trying to catch up to the rest of the manufacturers that have been using SCR, and it's good to see. Maybe Navistar will survive as a diesel engine manufacturer.

I sat through a presentation a couple of years ago given by Wayne Eckerle, who was director of research at Cummins. He discussed their on-highway emissions strategy. Cummins did an extensive design and testing program comparing EGR and SCR NOx control systems. After extensive testing, their decision was to go with SCR because there was a 10% fuel economy advantage, and the trucks would be cheaper to operate, even considering the cost of DEF.
_________________________
1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck

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#3331285 - 04/02/14 10:41 AM Re: Urea injection for diesel [Re: wemay]
BMWTurboDzl Offline


Registered: 04/15/10
Posts: 1329
Loc: Atlanta,GA
Well I read the newer off road Diesels can meet previous emissions requirements with SCR only. Seems getting to current on-road requirements is going to be tougher.
_________________________
'15 435i - Factory fill.
'10 335d (sold)

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#3332423 - 04/03/14 02:59 PM Re: Urea injection for diesel [Re: Wesbo]
stchman Offline


Registered: 09/25/13
Posts: 517
Loc: St. Louis, MO
Originally Posted By: Wesbo
Could you pee in the tank to get enough solution to get home? I'm only partly kidding...


Human urine does not contain near enough urea. DEF is ~32% urea while human urine is roughly 2.5% urea.
_________________________
2013 Chevrolet Silverado LTZ 2WD 5.3L
Mobil 1 5W-30
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#3332478 - 04/03/14 04:00 PM Re: Urea injection for diesel [Re: JHZR2]
Surestick Offline


Registered: 09/10/08
Posts: 65
Loc: Quebec, Canada
Originally Posted By: JHZR2
The regen thing I get, the warm up??? Other than some higher thermal efficiency, I dont see a substantial difference to warm up a diesel than a ga$$er, because if the same alloys, lube types, etc. are used, and the same power is output, its a matter of mass and heat capacity.

The diesel is more efficient, but the few % dont make a big difference given the quantity of waste heat. The engines are heavier, but that heat capacity difference can be calculated, and if normalized, wouldnt be any longer. Practically speaking it may not be any different.


At 20C outside there's no real appreciable difference - My Subaru will show normal temp in a couple of blocks, my VW TDI will take a block or two longer. At -20C the TDI won't be showing anything on the temp gauge after 5km, my Subaru will be halfway to warm. With heat on full blast at -20C, even on the highway, the TDI will show a few needle widths under normal temp until I back off the blower fan.

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#3332502 - 04/03/14 04:19 PM Re: Urea injection for diesel [Re: wemay]
Surestick Offline


Registered: 09/10/08
Posts: 65
Loc: Quebec, Canada
I believe that one of the reasons for this is that way a diesel burns fuel. Instead of a homogeneous mixture like in an SI engine the mixture in a diesel isn't homogeneous, it burns closer to the centre of the combustion chamber where it's injected. This leaves an insulating layer of air between the combustion process and the cylinder walls that reduces the amount of heat going into the coolant. It's kind of like a turbine engine which protects it's burner cans with relatively cool air flow from the compressor that's not used to burn fuel.

Obviously there's more going on, take model diesel engines vs. glow engines. They use a homogeneous mixture yet run cooler than the alcohol-fuelled glow engines.

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#3334950 - 04/06/14 12:48 PM Re: Urea injection for diesel [Re: wemay]
ac_tc Offline


Registered: 05/06/08
Posts: 540
Loc: sweden
Not so long ago every one was uppset by the fact that
you need to fill your diesel with urea and they thaught that urea was expensive....
So the manufacturers invented cooled egr....
_________________________
-98 Dodge Durango 5.9 4*4 HDEO 10w- 40 ci4
-04 PT Cruser GT 10w- 40 HDEO ci4
-Everything else HDEO 10w- 40 ci4/STOU 10w-30/THF

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#3336193 - 04/07/14 07:31 PM Re: Urea injection for diesel [Re: ac_tc]
artificialist Offline


Registered: 09/23/07
Posts: 6935
Loc: Florida
Originally Posted By: ac_tc
Not so long ago every one was uppset by the fact that
you need to fill your diesel with urea and they thaught that urea was expensive....
So the manufacturers invented cooled egr....

What I encountered was not that people were offended by having to buy DEF.
They were upset that the engine would have an extra thing that needed to be maintained.

And cooled EGR is used on engines with DEF.
_________________________
2010 Lancer Ralliart Sportback

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#3336245 - 04/07/14 08:16 PM Re: Urea injection for diesel [Re: artificialist]
AP9 Offline


Registered: 07/10/13
Posts: 219
Loc: Chicago suburbs
Originally Posted By: artificialist
Originally Posted By: ac_tc
Not so long ago every one was uppset by the fact that
you need to fill your diesel with urea and they thaught that urea was expensive....
So the manufacturers invented cooled egr....

What I encountered was not that people were offended by having to buy DEF.
They were upset that the engine would have an extra thing that needed to be maintained.

And cooled EGR is used on engines with DEF.


True, but Caterpillar ACERT and Navistar EGR engines (for 2010 EPA NOx emissions) really crank up the EGR, which puts quite a bit more of a load on the cooling system.

I'm not as well-versed on modern passenger car diesels, but I'd assume the same deal with them too.


Edited by AP9 (04/07/14 08:17 PM)

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#3336424 - 04/08/14 12:10 AM Re: Urea injection for diesel [Re: A_Harman]
TiredTrucker Offline


Registered: 01/04/08
Posts: 1091
Loc: Kellogg, IA
Originally Posted By: A_Harman
Navistar adopted the EPA's emissions control technology that relied heavily on EGR, and then found their engines couldn't pass production audit testing. Now they're trying to catch up to the rest of the manufacturers that have been using SCR, and it's good to see. Maybe Navistar will survive as a diesel engine manufacturer.

I sat through a presentation a couple of years ago given by Wayne Eckerle, who was director of research at Cummins. He discussed their on-highway emissions strategy. Cummins did an extensive design and testing program comparing EGR and SCR NOx control systems. After extensive testing, their decision was to go with SCR because there was a 10% fuel economy advantage, and the trucks would be cheaper to operate, even considering the cost of DEF.


That's true, Navistar went with high EGR, and got bit in the backside for doing so. That just makes things even more confusing. Since they bought a 50% share of Amminex, who makes SCR solid cartridges to use in place of DEF tanks, why didn't Navistar then, or now, go with the system. It seems like a best of all worlds solution. You get SCR to keep the EPA happy, and it is in a solid cartridge form that is designed to go the length of a typical oil change interval. Easy to take a used cartridge out and slide in a new one. And a spare cartridge could be carried in a side box if needed. No risk of spilling or corrosion.

Instead, they adopted Cummins SCR technology with DEF. Go figure.
_________________________
Hey there, VA, what do ya say? How many vets did you kill today?

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