Urea injection to reduce emmisions on diesels

[Henry W]

i just found that  a chemical called Urea is being used to reduce emmisions on some new diesels.

Does anyone know about this.

Henry

[CLC379]

i dont know much about it other than new class8 trucks here in the usa have the DEF diesel exhaust fluid, google SCR systems

i heard it was tried in europe resulting in more bad effects than good

[mobile_bob]

it is used in the new truck systems to reduce the nitrogenous oxide emissions of the diesel engines
to make them tier 4 compliant

bob g

[veggie]

I think the Mercedes (and others) "blue-tech" systems are based on this and have been using it for a few years.
Problem is that you have to go to the dealer to get a Urea recharge 
I heard on some of the new American diesel trucks (3/4 and 1 ton) that a recharge could be as often as every-other-month?
( for $100 per visit of course )
Anyone else heard about this.?

veggie

[Fat Charlie]

The new Dodges Rams use it.

The Diesel Exhaust Fluid Emissions system uses a Selective Catalytic Reduction (SCR). This is a technology that uses a urea based Diesel Exhaust Fluid (DEF) and a catalytic converter to significantly reduce nitrous oxides (NOx) emissions. The system accomplishes this by injecting small quantities of Diesel Exhaust Fluid (DEF) into the Selective Catalytic Reduction (SCR) where its vaporizes and decomposes to form ammonia and carbon dioxide. The Diesel Exhaust Fluid (DEF) Dosing Control unit is used to control the operation and monitoring of the DEF system. The ammonia is the desired by-product which in conjunction to the SCR Catalyst, converts the NOx to a harmless nitrogen and water. The SCR system is equipped with two NOx Sensors and modules that are used to monitor the efficiency of the SCR Catalyst and DEF system.

It seems like a secondary catalytic converter.  Lots of nanny-ware in the system, though.  Low fluid warnings on startup, then no fluid warnings.  Ignore the no fluid warnings for enough starts (or miles) and the truck's shutting down.  Dodge sells (what I think is a gallon of) exhaust fluid for $8.33.

[mike90045]

Customer:  I'd like a gallon of exhaust fluid, please

clerk:  Need any blinker fluid or muffler grease today ?

[Fat Charlie]

If you're out of exhaust fluid, it's probably because your muffler bearings are shot:

http://kalecoauto.com/index.php?main_page=product_info&cPath=3&products_id=10&zenid=0846fb1b1bd8a098288a06ae89f3b6cf

[Westcliffe01]

The expectation is that urea consumption would be about 2% of the fuel consumption at a cost of (fluctuates) $2.60/gal.   So a Dodge Ram getting 14mpg with a 30gal tank would need 0.6 gal of urea per fill up at a cost of $1.56.  If the urea tank holds 6 gal, you would need to top up the urea every 8-10 fillings.

The advantage of the SCR equipped truck is that they will get much improved mileage compared to the 2007 model year trucks.  And operation of the DPF's will be less troublesome now that passive regeneration is more feasible.  It is believed that the improved economy will more than offset the additional cost of the urea.   Unfortunately, for many ordinary people, we will never be able to afford the top of the line trucks that will be sold with these engines (average cost $63k +).

We desperately need Toyota to start selling their Hilux here with a 3.0 diesel to compete with these money pits.