Interesting Diesel Article

[Carpenterman]

Check it out:

Why Are Today's Diesels Only So-So Economical . . . and So Expensive? - EPautos

[bsmuwk]

Moral of the story here

The DOT is run by a bunch of dumbass'

[vstech]

yup.

[Dan Stokes]

The guy who wrote the article has pretty much no understanding of Diesel emissions regulation nor the reason behind them. That was my profession for 31 1/2 years and I actually know something about this.

The issue is that Diesels (notice that I have the courtesy to capitalize Mr. Diesel's last name) are very low in HC and CO emissions as well as fairly low in CO2 (basically, greenhouse gas) emissions but they make a ton of NoX which is more or less the catalyst in photochemical smog. EGR and other engine refinements reduce NoX but the levels are still high enough to require an aftertreatment system (laypeople would call that a "catalytic converter" which is not technically correct). The REASON for removing as much sulfur as possible from Diesel fuel is not to "reduce pollution" as stated in the article, it's to prevent poisoning the aftertreatment system. Sulfur will poison this system just like lead in gasoline will poison an Otto-cycle catalyst.

So what's the difference between European and US standards? European standards allow the manufacturers to require service facility-performed periodic maintenance on a vehicle's emissions system so in the case of Diesel-fueled vehicles the requirement is to have the aftertreatment system serviced periodically (I think it's every 10K miles or metric equivalent but don't hold me to that) and the reality is that here in the US we can't even get folks to bring their cars in for an oil change. Sad but true - as long as the car continues to move under it's own power folks will drive them. So the decision was made that Diesel vehicles had to have emissions systems that function without outside interference for the useful life of the vehicle. This makes for significantly different systems.

I do agree that there ought to be some way to "harmonize" (the term in the trade) the testing processes among nations but so far there has been little agreement on just how to do that. There is as much political discord as there is technical disagreement.

Dan

[ILUVMILS]

Originally Posted by Dan Stokes

...can't even get folks to bring their cars in for an oil change. Sad but true - as long as the car continues to move under it's own power folks will drive them.......


Dan

.........until they get the "20 key starts remaining/Refill Adblue" warning message!

[tjts1]

No one wants to choke on smog. But the truth is that’s not been an issue – much less a threat – for decades. We long ago reached the point of diminishing returns with regard to vehicle exhaust emissions. The proverbial low-hanging fruit has been picked. And there is very little left to be picked, even if we really stretch our arms.

This was written by an idiot.
http://www.lung.org/associations/states/california/assets/pdfs/sota-2013/sota-2013-san-joaquin-valley.pdf

[compu_85]

Originally Posted by ILUVMILS

.........until they get the "20 key starts remaining/Refill Adblue" warning message!

Our 2012 Passat uses AdBlue / Urea / Diesel Exhaust Fluid as part of its emissions control strategy. One tank full of DEF lasts ~20,000 miles. The car starts warning you at 1500 miles remaining and begins counting down. When it gets to 0 the engine will not restart, but also won't shut off. If there is a failure in the adblue system the count down is shorter, 600 miles as I recall.

Here's a video my friend Drew made showing the alarm: https://www.youtube.com/watch?v=YhPJaQt9FUs

If you can ignore the car dinging / beeping / flashing at you for 1500 miles you probably shouldn't be driving.

I refill the tank every oil change, adding ~2.5 gallons every 10,000 miles. It is not expensive, and only slightly inconvenient. The system works well and allows the car to break 50 mpg if you're easy on it... not bad for a car bigger than a W126 with an automatic! I'd have to look back at my records, but I recall the DEF costs something like $0.006 per mile.

-J

[Dan Stokes]

Compu 85 - 'Zakly!

I'm named on the patent using a small squirt of Diesel fuel instead of urea to regen the NoX biscuit - both work. The EPA was pushing the added fuel method for fear that US drivers would wire around the warning system that you described. So far it seems like compliance has been pretty good, though (YEAH!!!!). Thanks for relating your real-world experience.

If we were buying a new car for ME (the bride) we'd look VERY seriously at a VW Diesel.

Dan

[compu_85]

Dan,

So the system you designed is used on the prior Jetta / Golf then? Those have a NOx trap and H2S trap. The frequent regens those need make a bit of an economy hit compared to the Passat.

-J

[Dan Stokes]

Well, no, I didn't DESIGN it - but I was one of the testers and built a lot of the hardware in the test cell as well as writing the contracts and getting much of the hardware built by an outside vendor. I'm named at the end of the patent as a contributor.

Anyhow - I understand that VW is using that system on their lower HP engines. My guess is that they went that way because it's cheaper (no aux. tank, injector nozzle, piping, etc.) and the low HP engines are sold at a lower price.

We found that there was a 2% to 3% fuel economy hit. It's interesting that we'd hear all sorts of horror stories (mostly from engine manufacturers - they had a vested interest in NOT going to aftertreatment)) about horrid FE penalties but testing done in a controlled, repeatable circumstance consistently showed that 2-3% number. They eventually agreed with our numbers in a formal hearing though they didn't WANT to The engineers did the math and for operating costs it was about a wash between urea and the added fuel method.

Dan