Exhaust aftertreatment

In response to an increasing push for clean diesel emissions, medium and heavy duty �diesel-powered trucks have adopted complex exhaust or emission aftertreatment systems.
These systems treat post-combustion gases after they leave the engine, reducing �environmental impact without sacrificing power or performance.

1. EXHAUST AFTERTREATMENT SHIVLEELA S. ANGADI ADAM CENTRE, PUNE 12/03/2019 1

2. Why Exhaust aftertreatment ? 2 When engine is running and when process reaches at its last stage, it pass number of harmful substance through exhaust valve. Like NO, CO, NOx and many more. If these substance directly release to the atmosphere it will be harmful for all humans and can create other problem like global warming . Gases coming out after exhaust stroke are harmful in many ways. Fig. 1: Combustion process Source : www. Google.com/Combustion-process

3. 3 These harmful gases contains : Carbon monoxide  (CO) is a poisonous gas that is colorless and odorless. Hydrocarbons  or  volatile organic compounds  (VOCs) are a major component of smog produced mostly from evaporated, unburned fuel. Nitrogen oxides  (NO and NO 2 , together called NOx ) are a contributor to smog and acid rain, which also causes irritation to human mucus membranes . To avoid this catalytic converter is used which convert the harmful gases into harmless. Fig. 2: Exhaust Process Source : www. Google.com / Exhaust Process- Animation

4. CATALYTIC CONVERTER 4 A  catalytic converter  is an  exhaust emission control  device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants. The extreme heat in the converter oxidizes the exhaust that flows out of the engine . As a part of exhaust system catalytic converter has two roles: As emission control device – responsible for converting undesirable exhaust gases into harmless gases. Helps reduce noise level of exhaust system . C atalytic converters are also used on electrical generators, forklifts, mining equipment, trucks, buses, locomotives, and motorcycles. They are also used on some wood stoves to control emissions . Fig. 3: Diagramatic representation of Catalytic converter Source : www. Google.com/catalytic-converter

5. LOCATION OF CATALYTIC CONVERTER 5 This device is installed in the exhaust system between the exhaust manifold and the muffler, and usually is positioned beneath the passenger compartment. Fig. 4: Location of Catalytic converter Source : www. Google.com/Location-of-catalytic-converter

6. WORKING OF CATALYTIC CONVERTER 6 Fig. 5: Construction of Catalytic converter Source : www. Google.com/construction-of-catalytic-converter An internal combustion engine creates heat energy by igniting a mixture of gasoline and atmospheric oxygen with a high-voltage spark. Unfortunately , a residual quantity of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOX) are left over after combustion. Consequently , a catalytic converter uses precious metals like platinum as a catalyst to convert harmful pollutants like HC, CO and NOX into harmless gases like oxygen (O2), carbon dioxide (CO2) and water (H2O).

7. Since a catalyst will accelerate a chemical reaction without being consumed by the process itself, the catalytic convertor will theoretically last forever. In reality, catalytic converters eventually succumb to contaminants from coolant and engine oil additives and heat stress. 7 Fig. 6: Location of Catalytic converter Source : www. Google.com/Location-of-catalytic-converter

8. TYPES OF CATALYTIC CONVERTERS Two-Way Catalytic Converter Three-Way Catalytic Converter 8 Fig. 7: Two way Catalytic converter Source : www. Google.com/Two-way-catalytic-converter Fig. 8: Three way Catalytic converter Source : www. Google.com/Three-way-catalytic-converter

9. 1. Two-Way Catalytic Converter 9 It is widely used on diesel engines to reduce hydrocarbon and carbon monoxide emissions, and they were also used on spark ignition (gasoline) engines . Two-way catalytic converter performs two simultaneous tasks of oxidation of carbon monoxide of hydrocarbons to carbon dioxide and water . The first stage helps in reducing the amount of carbon monoxide emissions. In second stage hydrocarbons created by unburned fuel oxidizes to form carbon dioxide and water . Fig. 9: Two way Catalytic converter Source : www. Google.com/Two-way-catalytic-converter

10. Chemical reaction A two-way catalytic converter has two simultaneous tasks : Oxidation of carbon monoxide to carbon dioxide: 2. Oxidation of un-burnt and partially-burnt hydrocarbons to carbon dioxide and water : Disadvantage : I nability to control  oxides of nitrogen 10 2 CO + O 2  → 2 CO 2 C x H 2x+2  + [(3x+1)/2] O 2  → x CO 2  + (x+1) H 2 O (a combustion reaction)

11. 2. Three-Way Catalytic Converter 11 Fig. 10: Three way Catalytic converter Source : www. Google.com/Three-way-catalytic-converter Similar to the oxidation converter, the reduction catalytic converter helps to eliminate hydrocarbons and carbon-monoxide emanations , in addition to oxides of nitrogen discharges, or NO x . NO x outflows are created in the motor burning chamber when it reaches extremely high temperatures more than 2,500 degrees Fahrenheit , approximately. The two processes that takes place in a Three way catalytic converter are: Reduction Catalyst Oxidation Catalyst

12. Chemical reaction 12 1. Reduction of nitrogen oxides to nitrogen and oxygen: 2. Oxidation of carbon monoxide to carbon dioxide: 3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water : 2NO x → xO 2 + N 2 2CO + O 2 → 2CO 2 C x H (2x+2) + [(3x+1)/2]O 2 → xCO 2 + (x+1)H 2 O Three-way catalytic converter - how does it work.mp4 Fig. 2: Three way Catalytic converter Source : www. Google.com/Three-way-catalytic-converter-gif

13. Difference of emission from diesel cars and petrol cars 13 Fig. 12: Emission standard limits Source : www. Google.com/emission-from-diesel-engine

14. 14 0.180 0.230 0.080 0.170 0.080 0.170 CO = Carbon Monoxide THC = Hydrocarbons NMHC = Volatile O rganic C ompounds Nox = Nitrogen oxides HC+NOx PM = Particulate Matter PN = Particle N umber of thermodynamic system 0.50 0.560 0.25 0.30 0.180 0.230 14

15. EXHAUST AFTERTREATMENT system 15 In response to an increasing push for clean diesel emissions, medium and heavy duty diesel-powered trucks have adopted complex exhaust or emission aftertreatment systems. These systems treat post-combustion gases after they leave the engine, reducing environmental impact without sacrificing power or performance. The primary components of a vehicle’s aftertreatment system are : Diesel Oxidation Catalyst (DOC) - reduces particulate matter and oxidizes carbon monoxide and hydrocarbons. Diesel Particulate Filter (DPF) - This filter is designed to remove more than 90% of particulates out of the exhaust. Selective Catalytic Reduction System (SCR) - which reduces nitrogen oxide ( NO x ) into N 2 Fig. 13: Catalytic converter Source : www. Google.com/catalytic-converter

16. 16 DOC DPF SCR DEF Exhaust gases leave engine Oxidation of CO and HC Particulates(PM) trapped in diesel particulate filter DEF injected into exhaust NOx reduction in SCR Reduced volume of emission leaves tailpipe. PM and NOx near zero levels. Process of diesel emission control system Fig. 14: Process of diesel emission control system

17. 1 . Diesel oxidation catalyst (DOC) Diesel Oxidation Catalyst ( DOC ) is specially designed for diesel engine. A Diesel Oxidation Catalyst ( DOC) is an aftertreatment component that is designed to convert carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide (CO 2 ) and water(H 2 O).   DOC’s are maintenance free, inexpensive and simple in construction and are suitable for all types of diesel engines. The exhaust coming from the engine first passes through the DOC. It is mainly used for oxidizing nitrogen monoxide (NO) to nitrogen dioxide (NO 2 ), substances that together create NOx. However, the DOC also has another important function, which is related to regeneration of the DPF. 17 Fig. 15 Diesel oxidation catalyst Source : www. Google.com/ Diesel-oxidation-catalyst

18. 2. Diesel Particulate Filter ( dpf ) The DPF comes after the DOC in the exhaust aftertreatment system.  T he DPF removes most of the soot particles (more than 99 %) from the exhaust gases. The exhaust gases pass through the filter, which collects particles from the gases. The particles eventually turn into a soot cake. The increasing amount of soot will create a high pressure in the DPF, which means the soot needs to be removed. This can be done either by stand still regeneration or passive/moving regeneration 18 Fig. 16 : Diesel Particulate Filter Source : www. Diesel Particulate Filter

19. Filters are made up of porous, catalytically coated silicon carbide material that traps exhaust particulates. Diesel particulate filters operate by trapping soot particles from the engine exhaust, preventing them from reaching the environment.   The DOC and DPF work at the front end of the system to reduce carbon monoxide and hydrocarbons , but more importantly, capture soot and ash in the exhaust system to reduce the risk of those particles reaching the atmosphere. 19 Fig. 17 : W orking of Diesel Particulate Filter Source : www. Google.com / Diesel Particulate-Filter-working

20. Completely eliminates exhaust smoke even though sudden acceleration and rapid driving changes . The particulate filter is designed to trap and retain the solid particles until the particles can be oxidized or burned in the DPF itself, through a process called regeneration . There are three different types of regeneration: Stand Still Regeneration Moving Regeneration Passive Regeneration 20 Fig. 18 : Diesel Particulate Filter Source : www. Google.com / Diesel Particulate Filter

21. 3. Selective Catalytic Reduction (SCR) Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that injects a liquid- reductant agent through a special catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF ) or AdBlue . R educes levels of NOx using ammonia as a reductant within a catalyst system. The chemical reaction is known as "reduction" where the DEF is the reducing agent that reacts with NOx to convert the pollutants into nitrogen, water and tiny amounts of CO 2 . SCR technology alone can achieve NOx reductions up to 90 percent . 21 Fig. 19: Selective catalytic reduction Source : www. Google.com/Selective-catalytic-reduction

22. reaction 22 Exhaust gas treatment for passenger cars and light commercial vehicles - Denoxtronic.mp4 Fig. 21: Selective catalytic reduction Source : www. Google.com/Selective catalytic reduction Fig. 20 : Selective catalytic reduction Source : www. Google.com/Selective catalytic reduction graph

23. Diesel exhaust fluid(DEF)/ a dBlue Diesel exhaust fluid  ( DEF ) is an aqueous urea solution made with 32.5% urea  and 67.5% deionized water which is injected on the exhaust gases coming out of DPF. AdBlue  was  invented  by the German Association of the automobile industry (VDA) The DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and tiny amounts of carbon dioxide (CO2), natural components of the air we breathe, which is then expelled through the vehicle tailpipe . 23 Fig. 22: Diesel exhaust fluid(DEF )/ AdBlue Source : www. Google.com/ Diesel-exhaust-fluid

24. When the fluid gets hot, the water evaporates and the urea converts to ammonia. The ammonia reacts with a special catalyst in the SCR muffler and converts the NOx to nitrogen and water . AdBlue has different names in different countries such as, outside of Europe as DEF, ARLA 32 or AUS 32 in some countries Amount of AdBlue injected is dependent on the speed and the load of the engine . AdBlue should be  kept in the optimal conditions — out of direct sunlight and at a temperature between -6°C and 25°C — your  AdBlue can  last up to 18 months in storage. AdBlue  is not flammable, nor is it considered a hazardous liquid. It is a water-based urea solution, and poses little risk to humans. If you have sensitive skin, it might be wise to wear gloves when handling the liquid to avoid any potential irritation . 24 Fig. 23: Diesel exhaust fluid(DEF )/ AdBlue Source : www. Google.com/ Diesel-exhaust-fluid

25. 25 reaction Mercedes-Benz AdBlue Technology.mp4 Fig. 24: Reaction Diesel exhaust fluid Source : www. Google.com/ Diesel exhaust fluid

26. FAQ Is AdBlue a toxic solution ? Is the 32.5% urea solution critical ? What is the freeze point of AdBlue ? With a freezing temperature of -11 deg C, what happens to the operation of the vehicle if the AdBlue freezes ? Will there be special equipment to ensure the AdBlue does not freeze, or can be thawed if it does freeze ? Is AdBlue corrosive ? If AdBlue is corrosive to aluminium , what will the AdBlue tanks be made of ? How much AdBlue will a vehicle consume? Testing of Diesel Exhaust Fluid Diesel Exhaust Fluid Testing.mp4 26

27. Exhaust gas aftertreatment – explained in a simple way!.mp4 27

28. THANK YOU 28