The modern Diesel engine is one of the most versatile power sources available for mobile applications. The high fuel economy and torque of the Diesel engine has long resulted in global application for heavy-duty applications. Moreover, the high power and excellent driveability of today's turbo-charged small high-speed Diesel engines, coupled with their low CO2 emissions, has resulted in an increasing demand for Diesel powered light-duty vehicles.
However, the demand for Diesel vehicles can only be realised if their exhaust emissions meet the increasingly stringent emissions legislation being introduced around the world. In the USA, both HDD and LDD vehicles are meeting strict emissions legislations since 2007 with the introduction of particle filters which will be further restricted from 2010 with the use of additional NOx contr5ol systems. In Europe, similar strict requirements are being implemented with Euro IV, Euro V and finally through Euro VI legislations. In practice, such targets mean very high reductions (up to 90%) of nitrogen oxides (NOx) and particulate matter (PM) emissions are being required from previous levels.
This paper reviews the developments in Diesel exhaust emissions control devices and strategies that are being utilized to meet existing and upcoming Euro IV emission legislations for HDD vehicles around the world. The application of Diesel oxidation catalysts, flow though particulate filters, and NOx control catalysts (Selective Catalytic Reduction systems) to help meet such heavy-duty legislations are discussed. A comparative analysis of the different options is presented.