Recent developments in the field of automotive exhaust sensing

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Moos, Ralf:
Recent developments in the field of automotive exhaust sensing.
2007
Event: 7th East Asian Conference on Chemical Sensors (EACCS 7) , 03.-05.12.2007 , Singapur.
(Conference item: Conference , Speech )

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Steadily increasing emission standards for both passenger cars and heavy duty vehicles combined with the need for fuel efficiency lead to novel powertrain concepts like the leanly operated gasoline direct injection engine, or to novel exhaust gas aftertreatment concepts like NOx storage catalysts, ammonia SCR (selective catalytic reduction) NOx reduction, or even to a combination of both (DaimlerChrysler’s Bluetec I). Also, soot filters have been serialized. In order to control the novel powertrain and/or exhaust gas aftertreatment systems and to monitor on-board the proper operation of these systems (on-board diagnosis, OBD), novel exhaust gas sensors are required or would at least be very helpful. NOx sensors, NH3 sensors and sensors to detect the ammonia loading of SCR catalysts are under development or in the research state. Hydrocarbon sensors are in discussion for on-board diagnosis (OBD) for future cars having very low emission limits. Soot sensors are under study. This brief overview focuses on sensors for lean-burn engines. It reviews the latest published results on NH3 sensors and on sensors to detect the ammonia loading of SCR catalysts. Additionally, sensors for determining the exhaust gas recirculation rate are reviewed. Further novel concepts for exhaust gas sensing will be shown. In this talk, it will be also shown how development of exhaust gas sensors has always to be considered in interaction with exhaust gas aftertreatment systems. Hence, novel kinds of sensors have gained in importance just recently, when stricter emission regulations were announced, meaning that time is ripe for novel exhaust gas aftertreatment concepts. However, it is clear that all novel sensors do not only have to meet the technical requirements of the automotive industry but also have to be very inexpensive, reliable, and cost-effective.