This is basically how most adBLUE SCR systems work. However, one must consider the EGR (both in cylinder and otherwise) as well as plain old regular exhaust temperatures.
STAGE 1
Exhaust emissions from the diesel engine enter the diesel oxidation catalyst to reduce the amount of carbon monoxide (CO) and unburned hydrocarbons (HC).
STAGE 2
Emissions are processed through an advanced NOx storage catalyst (NSC). Nitrogen oxide emissions are stored during periods of lean engine operation, cycled for approximately 120 to 180 seconds. Regeneration of the catalyst is accomplished by changing the engine fuel-air ratio to a richer operating condition. The regeneration cycle lasts for approximately 2 to 4 seconds, releasing ammonia into the exhaust. This is where say the 2009 Cummins is different from the 2010 as it doesn't release any ammonia.
STAGE 3
A diesel particulate filter traps the particulate matter and soot. As soot is filtered, pressure sensors at the inlet and exit of the filter detect changes in pressure, notifying the engine control unit that the filter is full and to increase the exhaust temperature. The hot exhaust purges the filter in pulses lasting approximately 2 to 4 seconds, burning off the soot. These pulses will last for several minutes. Without ammonia on board the DPF plugs faster, esp. if it is not run hard (hot). This is the down fall of the 6.7L Cummins for sure.
STAGE 4
Ammonia from the NSC is stored in an SCR converter. The stored ammonia reacts with the catalyst, removing the remaining NOx emissions. The final by-products are nitrogen
and water vapour, gases that occur naturally in the air.

 

Thing I dont understand, I talked to several guys driving big trucks with the new emissions crap on em and they all tell me that their fuel economy basically has dropped in half. So if that is true, how are we actually saving and protecting the environment and reducing fuel consumption when we are getting less use out a gallon of fuel and we are in turn having to use MORE fuel then we did before. Wouldnt burning more fuel in the end emit more emissions into the environment and continue our demand for foreign oil? Seems to me the Government is actually going backwards on this instead of moving ahead in a positive way. Also adding one more expense to our already over loaded lives isnt going to help the economy rebound.

 

Well, here's the thing:

Tier 2 was for the most part controlled with EGR and just a DPF - this as we now know is a waste of fuel and a big problem. In cylinder EGR causes the truck to run hotter than needed which in turn is problematic for most of the diesel engines out there. The filters plug up based on real world working conditions and when they have to regen they signal a greater use of fuel.

Another way of looking at it is this, Tier 2 was nothing more than a transition from previous generations of emissions controls which were different based on the fuel you burnt. Tier 3 and the future Tier 4 are not dependant on fuel and are across the board. So assuming I am reasonably correct, Tier 2 was nothing more than a bench test that showed it could be done while Tier 3 indicates that it must be done.

Although the ratings are slightly different the EU has used a variation of Tier 3 for many years and this is what the use of Urea is so popular over there.

So, we should see economies come back, again based on what I understand to be correct by 2011 when T3 is in full effect. What tends to happen unfortunately is that the Bean Counters of a company will allow the purchase of a late model truck, in this case 2009, because it is the devil they know vs. the one they don't. All that does in this case is result in lower economies.

So, let's say a Class 8 with a EGR / DPF combo gets 3.5 MPG they should see increases to approximately 4.5 to 6 with a EGR / DEF / DPF since the DPF won't plug as often and therefore causing additional fuel to be used to clear it, improving economy somewhere between 5% and 40% depending on the vehicle, the SCR system and the driving / hauling style.

You're right though, improvements should result in cleaner and less fuel being used, most certainly not more.

 

The only pollutant that must be produced when a fuel is burned is CO2.

DPF's, catalytic converters, EGR, crankcase filters, smog pumps, and most every other emissions device in history has reduced NOx, CO, particulate matters/ VOC's/HC's, ozone, and almost every other emission at the cost of increasing the amount of fuel burned and subsequent CO2 emissions.

Most pollution equipment reduces fuel economy by a lot less of a percentage than by what it decreases pollution. Over the past thirty years vehicles have reduced some emissions by 99%, so even with a 25% fuel consumption increase you still have substantial emissions reductions.

But EPA regulations have resulted in who knows how many billions of extra gallons of fuel over the last 40 years. It's hilarious that EPA policy has been the largest factor in the increased production of greenhouse gases in the United States since it's founding, and even with the current global warming/ foreign dependency crises the EPA continues be seen as blameless in the whole affair.

The EPA actually had to prove in court recently that CO2 was a pollutant and under their power to regulate, which is what cleared the CO2 cap-and-trade legislation currently in the Congress. The hypocrisy is fascinating.

Now, I fully support the reduction of other pollutants at the expense of CO2, because pollutants other than CO2 actually cause damage...

 

how about third world buttmunch countries not having to do crap

 

 

Carbon monoxide, particulate matter and oxides of nitrogen are the most damaging emissions, and their effects are well localized. Apart from the occasional freak cloud, emissions of these pollutants from China and India have little effect on us. These are the pollutants that like to hang out around major metropolitan areas, create perma-smog and cause kids on playgrounds to keel over with asthma, bronchitis and eventually COPD.

The pollutant that people are trying to wrangle India and China into regulating as part of a global pact is CO2, which supposedly effects everybody on the world through global warming. Otherwise it's totally benign and helps plants grow. The attempts to force India and China into CO2 regulation have infinitely more to do with politics than health concerns.

The global prohibition of CFC's in the 90's is an example of the world's developing and developed countries coming together in the face of a genuine threat to the environment. But restrictions on the creation of CO2 in developing countries would put a limit on their total energy consumption and delay growth considerably, which is borderline malicious and tough to sell in the name of something hokey like global warming.

 

let the coal roll it's to late the earth is not going to get cleaner by putting this suff on these trucks should of done it when the first diesel was made. plus a new gas engine put out more emissions than old 12v. why pick on the diesels it these big power plants burning tons of coal a hour.

 

The EPA picks on coal plants plenty as well. They also produce fractions of emissions that they did 20 years ago.


Diesel vehicles emit no carbon monoxide, less CO2, more sulfur, more hydrocarbons and similar levels of NOx. Although current regulations set the emissions of either fuel source very close to each other.


Air quality in major cities today is better than it was decades ago, entirely as a result of vehicular and industrial emissions controls. EPA regulations have worked for their intended purposes.

Outside the Box - WSJ.com

 

Carbon Dioxide is what we breathe out right, and Carbon Monoxide is that bad stuff they are "claiming" is hurting the environment, right?? because the plants and the algae in the ocean are what process the Carbon Dioxide your telling me that there isnt nothing in nature that can process Carbon Monoxide and at least clean it up enough that it won't, as they say, hurt us. I dont buy that at all....


I really am against this crap, the EPA has taken this stuff to the next level and they were not intended to regulate our lives like they do...

But its already to late for us people that dont believe that stuff, because they have already got probably 70% of the population to believe it.