1. Diesel Exhaust Emissions
PM and NOx After treatment
Regeneration Theory
Reason for Regeneration
Differences of PM, Soot, Ash and Nox
Regeneration Process
After treatment components and functions

2. Terminology TECHNICAL TERM CUSTOMER TERM OTHER COMMON TERMS
Aftertreatment System
Exhaust Filter System
Exhaust Filter
Diesel Oxidation Catalyst (DOC)
Diesel Particulate Filter (DPF)
Aftertreatment Device (ATD)
Regeneration
Passive
Active (Auto)
Parked (Manual)
Service
Exhaust Filter Cleaning
Natural
Auto
Manual
DPF Recovery
Fuel Dosing System
Hydrocarbon Dosing System
Particulate Matter (PM) Soot
Soot
Particulate Matter
Ash
Ash Removal
Ash Cleaning
There are many different terms that are usd when discussing an Aftertreatment System. The customer terms are term that may be used in customer focused material and the ocomon terms may be used by the industry at large.

3. Diesel Emissions Controls
Today, viable emission control technologies exist to reduce exhaust emissions
from existing diesel vehicles.
Retrofit technologies designed to control particulate matter (PM) include:
• Diesel oxidation catalysts (DOCs)
• Diesel particulate filters (DPFs)
• Flow through filters (FTFs)
• Closed crankcase ventilation (CCV)
Retrofit technologies designed to control oxides of nitrogen (NOx) include:
• Exhaust gas recirculation (EGR)
• Selective catalytic reduction (SCR)
• Lean NOx catalysts (LNCs or HC-SCR)
• Lean NOx traps (LNTs)

4. Diesel Oxidation Catalyst
Diesel oxidation catalysts (DOCs) installed on a vehicle’s exhaust system can reduce total PM by as much as 25 to over 50 percent, depending on the composition of the PM being emitted. Diesel oxidation catalysts can also reduce smoke emissions from older vehicles and virtually eliminate the obnoxious odors associated with diesel exhaust.
A diesel oxidation catalyst (DOC) is a flow through device that consists of a canister containing a honeycomb-like structure or substrate. The substrate has a large surface area that is coated with an active catalyst layer. This layer contains a small, well dispersed amount of precious metals such as platinum or palladium. As the exhaust gases traverse the catalyst, carbon monoxide, gaseous hydrocarbons and liquid
hydrocarbon particles (unburned fuel and oil) are oxidized, thereby reducing harmful emissions .Oxidation catalysts can reduce more than 90 percent of the CO and HC emissions and more than 70 percent of the toxic hydrocarbon emissions in diesel exhaust.

5. Diesel Oxidation Catalyst
Like catalytic converters already used on all gasoline vehicles, diesel oxidation catalysts (DOCs) cause chemical reactions to reduce emissions without any moving parts.
The catalysts reduce particle emissions by as much as 50%, can reduce visible smoke, and eliminate the odor of diesel exhaust.
The catalysts can reduce the invisible ozone forming hydro-carbon gases by more than 70% and CO by up to 90%
DOCs are used in new vehicles and can be installed on retrofitted vehicles already in use.
Can be used with D2, biodiesel, emulsified diesel, ethanol/diesel blends and other alternative diesel fuels
Usually not a Level 3 device

6. Diesel Particulate Filter Sintered Metal or Wire Mesh
Flow-through filter (FTF) technology or partial filters employ catalyzed metal
wire mesh structures or tortuous flow, metal foil-based substrates with sintered metal sheets to reduce diesel PM. Technologies verified to date employ catalysts and/or fuel borne catalysts to oxidize soot. This technology is more widely applicable on older, dirtier engines than wall-flow filters because it is much less likely to plug and most often does not require ash cleaning. Flow-through filters are capable of achieving PM reduction of about 30 to 75%, as well as trapping the sub-micron, ultrafine particles capable of penetrating deep into the lungs. FTFs can be catalyzed to offer co-benefits of reducing HC, CO, and toxics of up to 80-90%.

7. Diesel Particulate Filter Wall-flow Monolithic Substrate
Diesel particulate filter is a “wall flow” filter which is made up of a large number of small channels which are alternately open or plugged at the inlet / outlet ends of the DPF substrate.
The engine exhaust gases and PM are forced to flow through the internal porous channel walls of the filter substrate core due to the alternating inlet / outlet plugs.
The PM is trapped within the internal porous walls of the substrate core due to the sieving action of the internal pores and the agglomeration action of PM.
Changes in the porosity of the substrate channel walls, the substrate channel cell density, substrate volume and other variables can be altered to increase PM trapping efficiency and reduce exhaust gas backpressure restriction.
Diesel particulate filter substrate cores are available in Cordierite Ceramic or Silicon Carbide material compositions.
Each substrate core material composition has inherent advantages and disadvantages.
Silicon Carbide substrate cores have a higher resistance to thermal stress in comparison to Cordierite Ceramic substrate cores.
Silicon Carbide substrate core has a higher capacity per liter of filter volume in terms of PM mass in comparison to a Cordierite Ceramic substrate core.
Silicon Carbide substrate cores are more expensive in comparison to Cordierite Ceramic substrate cores.
Silicon Carbide substrate cores are heavier in comparison to ceramic substrate cores

8. Wall Flow DPF

9. DOC / DPF
The DOC generates heat for the DPF, The DPF traps PM or soot. The engine, DOC and DPF must be matched for proper operation

10. Diesel EGR

11. LOW pressure EGR With DPF
As the name implies, EGR involves recirculating a portion of the engine's exhaust
back to the charger inlet or intake manifold, in the case of a naturally aspirated engines.
In most systems, an intercooler lowers the temperature of the recirculated gases. The
cooled recirculated gases, which have a higher heat capacity than air and contain less
oxygen than air, lower combustion temperature in the engine, thus inhibiting NOx
formation. Diesel particulate filters are always used with a low-pressure EGR system to ensure that large amounts of particulate matter are not recirculated to the engine. EGR systems are capable of achieving NOx reductions of more than 40 percent.

12. 2010 On-Highway
Urea is a nitrogen compound that turns to ammonia when heated. 
When a urea-and-water solution is injected into the exhaust stream and passed over a catalyst, the urea reacts with the NOx to form nitrogen and water vapor -- two clean and harmless components of the air we breathe.
The basic elements of the SCR system:
SCR catalyst aftertreatment chamber
DEF tank
Pump & lines
Heating system
Control & monitoring system

13. 2010 SCR w/ DEF system
SCR is an exhaust aftertreatment that controls emissions downstream from the engine. SCR takes place after the combustion process, and utilizes diesel exhaust fluid (DEF) to reduce NOx levels.
With SCR, DEF is injected into the exhaust stream which reacts with the NOx in the SCR catalyst, forming harmless nitrogen and water. SCR allows the engine to function at higher and more optimal combustion temperatures, providing increased fuel efficiency and power.
To achieve the extremely low NOx levels required by EPA 2010, most major engine
manufacturers use an SCR process that also employs EGR. This proven method of
combining EGR and SCR technologies applies the best of both technologies to efficiently reduce harmful emissions and provide better engine performance.