bluetec-diesel emission control system

P.E.S COLLEGE OF ENGINEERING, MANDYA(An Autonomous Institution under VTU)

DEPARTMENT OF AUTOMOBILE ENGINEERING 2011-2012

A Seminar Topic report on

BLUETEC Diesel Exhaust Treatment SystemSubmitted By, Abhishek. V [4PS08AU002] Under the Guidance of

Dr. B. Jayashankara,Professor Department of Automobile Engineering

Signature of the Guide

[Dr. B. Jayashankara]

BlueTec Diesel Exhaust Treatment System

ACKNOWLEDGEMENT

I would like to convey my gratitude and respect to my resourceful guide, mentor, Dr. B. JAYASHANKARA, Professor, Department of Automobile Engineering, P.E.S.C.E, Mandya for his invaluable guidance and support which was instrumental for the successful completion of the seminar. I would like to express my sense of gratitude to Dr.J.VENKATESH, Professor and Head of the Department, Automobile Engineering Department, and Dr.V.SRIDHAR, Principal, P.E.S.C.E, Mandya. It was their constant encouragement and inspiration that enabled me to successfully complete the seminar work. I would also like to thank the entire teaching faculty, non-teaching staff, my friends and family who continue to support me in all of my endeavours.

-Abhishek.V Date: 28th April, 2012

Dept. of Automobile Engg, PESCE

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Table of Contents

1. Introduction -------------------------------------------------------------- 01 - 03

2. The Diesel Engine ------------------------------------------------------- 04 - 05

3. Diesel Exhaust Emissions ---------------------------------------------- 06 -10

4. Present Day Exhaust Emission Control Technologies ---------- 11 - 23

5.

BlueTec by Mercedes Benz -------------------------------------------24 - 28

6.

Working Principle of BlueTec --------------------------------------- 29 - 36

7.

Advantages and Disadvantages of BlueTec ----------------------- 37 - 38

8. Conclusion ---------------------------------------------------------------------- 39

9. Bibliography and References ----------------------------------------------- 40


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Index

1.

Table 1 - Composition and temperature of diesel exhaust gas ------ 02 Figure 4.1a : Diesel Oxidation Catalyst ---------------------------------- 12 Figure 4.1b : SCR system --------------------------------------------------- 13 Figure 4.1c : Lean NOx Catalyst ------------------------------------------- 14 Figure 4.2a : Flow Through Filters ---------------------------------------- 16 Figure 4.2b : Diesel Particulate Filter ------------------------------------ 18 Figure 4.4a : Low-pressure EGR + DPF --------------------------------- 21

2.

3. 4. 5.

6. 7.

8. Figure 4.5a : Crankcase emission control system ---------------------- 23 9. Figure 5.2a : Market Share of different fuelled Mercedes-Benz vehicles worldwide -----------------------2510.

Figure 6.1a : Schematic process flow of BlueTec -------------------- 30 6.1a : Figure 6.1c : Process flow of a Selective Catalytic Reducer ------------------------------ 33

11. Figure

12.

Figure 6.1d : SCR + DeNOx tronic system ------------------------------ 34


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1. IntroductionNowadays, peoples concern about the environment is raised everywhere, especially about air pollution. Air pollution constitutes an ominous threat to human health and welfare. Its adverse effects are pervasive and may be disaggregated at three levels: (a) local, confined to urban and industrial centers; (b) regional, pertaining to trans boundary transport of pollutants; and (c) global, related to build up of greenhouse gases. These effects have been observed globally but the characteristics and scale of the air pollution problem in developing countries are not known; nor has the problem been researched and evaluated to the same extent as in industrialized countries. Air pollution, however, can no longer be regarded as a local or a regional issue as it has global repercussions in terms of the greenhouse effect and depletion of the ozone layer. There are different scales of air pollution: global (CO2, CH4, N2O, CFCs), continental (SOx, NOx), regional (fly ash, photochemical smog), local (large particulates).

1.1 Exhaust Emissions from Diesel Engines The primary and secondary constituents of the exhaust gases produced by diesel engines are listed together. Table 1 provides information on the composition and temperature of the exhaust gases from diesel engines.

1.2 Mixture Formation The fuel used in diesel engines has a higher boiling point than that used in gasoline engines. In addition, the A/F mixture in diesel engines is formed quickly just before combustion starts and is therefore less homogeneous. Diesel engines operate with excess air across their entire operating range. An insufficient quantity of excess air results in increased particulate emissions (soot), and CO and HC emissions.

1.3 CombustionDept. of Automobile Engg, PESCE Page 5


The start of injection marks the initiation of the combustion process. The engines efficiency is determined by the start of combustion and by the combustion characteristics. The characteristics (as a function of time) of the injected fuel quantity and the injection pressure can be applied to control the combustion characteristics. These factors also determine the combustion temperature which. In turn, has a significant effect on the formation of nitrogen oxides (NOx).

Table 1: Composition and temperature of diesel exhaust gas Exhaust-gas components and temperature Nitrous oxides (NOx) Hydrocarbons (HC) Carbon monoxide (CO) Carbon dioxide (CO2) Water Vapour Oxygen Nitrogen, etc Smoke number, passenger cars Exhaust-gas temperature downstream of exhaust valve 1.4 NOx NOx is a generic term for mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. In areas of high motor vehicle traffic, such as in large cities, the amount of nitrogen oxides emitted into the atmosphere as air pollution can be significant. NOx gases are formed everywhere where there is combustion like in an engine. In atmospheric chemistry, the term means the total concentration of NO and NO2. NOx react to form smog and acid rain. NOx are also central to the formation of tropospheric ozone.Dept. of Automobile Engg, PESCE Page 6

At idle Ppm ppm C1 Ppm Vol% Vol% Vol% Vol% 50200 50500 100450 3.5 24 18 Residual SZ