Possibilities to Achieve Future Emission Limits for HD DI Diesel Engines Using Internal Measures 2005-01-0377

The diesel engine is currently the most efficient powertrain for vehicle propulsion. Unfortunately it suffers from rather high particulate and NO_x emissions that are directly related to its combustion mechanism. Future emission legislation requires drastic reduction of NO_x and particulate matter compared to present values. Engine manufacturers in their effort to meet these limits propose two solutions: reduction of pollutants inside the combustion chamber using internal measures and reduction at the tailpipe using aftertreatment technology. Currently there are various opinions considering the final solution. Taking into account information related to aftertreatment technology, an effort should be made to reduce pollutants inside the combustion chamber as much as possible. The last is obvious if we account for the even more strict emission limits to be applied after 2010 that will require a combination of aftertreatment and internal measures. For this purpose it is examined in the present using a simulation tool the possibility for achieving EURO-V emission limits using conventional DI diesel engine combustion technology and internal measures only. Towards this aim, the advancement of fuel injection timing and the increase of injection pressure in conjunction with the increase of EGR rate and boost air pressure are considered. These technologies are evaluated comparing performance and emission data against experimental ones referring to the baseline operation of a single cylinder HD DI diesel test engine. The results are used to examine the potential for meeting EURO-V emission limits using the previous combination of internal measures. The idea is to control soot using internal measures only and use A/T devices to control NO_x emissions where necessary. From the results obtained, indication is also provided for the required efficiency of after-treatment systems to fulfill future emission limits. Thus one can decide to use internal measures to control emissions up to a certain point and/or less demanding aftertreatment systems to further fulfill his requirements. Another outcome of the present analysis is the information provided concerning the required increase of boost pressure, which will be demanded by future boost air systems.