Semi-Empiric Model Based Approach for Dynamic Prediction of NOx Engine Out Emissions on Diesel Engines Prodrive Automotive Technology Limited

Format:

Conference/Event

Author/Creator:

Hegarty, Hegarty, author.

Contributor:

Favrot, Romain

Rindone, Gianfranco

Rollett, Dave

Conference Name:

SAE 2010 World Congress & Exhibition (2010-04-13 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2010

Summary:

NOX emissions are one of the major limiting factors of moderndiesel engine technology; they heavily influence, directly orindirectly, both engine and after-treatment design, cost,complexity and reliability; they are also linked in an importanttrade-off with CO₂ emissions and therefore fuel consumption. It isparamount for OEMs (Original Equipment Manufacturers) to exploitmore sophisticated techniques for modeling the formation of NOXto reduce costs and increase their ability to meet the legislativerequirements for both CO₂ and NOX. Many existing simulationmodels predict NOX simply by interpolating steady state enginemaps with limited ability to efficiently capture the effects ofengine warm up, speed-load transients and air system dynamics. Forconventional powertrains running on light cycles this might stillbe acceptable, but it becomes inadequate when applied to fast anddeep transients across unconventional speed and load patterns. Onthe other side of the spectrum, extremely sophisticated, fullypredictive combustion models are just too complex to be attractiveas a development tool.The objective of this paper is to describe a semi-empiric modelbased approach for dynamic NOX emission modeling that is beingdeveloped by Prodrive as part of the FHSPV (Flywheel Hybrid Systemfor Premium Vehicle - www.FHSPV.org) consortium. The requiredmeasured data are kept to a minimum and are still primarily basedon stationary engine maps recorded on test bed. These mapsdetermine the steady state component of the NOX prediction, thedynamic part being calculated based on key engine parameters. Fromonboard sensor data the model calculates in-cylinder conditions atInlet Valve Closing (IVC); based on an average wall temperature itthen calculates the conditions at the start of the compressionstroke and, based on a Wiebe heat release model, it determines thedegree-by-degree profiles for pressure and temperature. The modeluses a simplified Zeldovich mechanism to calculate NOX. Theresult is used to validate the model against the measuredsteady-state engine maps. Attention will be given to thecorrelation process that enables the shift from an angle-based to atime-based domain as this is a key aspect of this approach and onewhich can be finely tuned to vary the fidelity of the model basedon the requirements of the end-user.In conclusion the paper demonstrates the predictive performanceof the model in relation to transient events within the NEDC (NewEuropean Drive Cycle). It also lists key advantages and suggeststhe next steps to address its limitations

Notes:

Vendor supplied data

Publisher Number:

2010-01-0155

Access Restriction:

Restricted for use by site license