This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Transient Build-up and Effectiveness of Diesel Exhaust Gas Recirculation
ISSN: 1946-3936, e-ISSN: 1946-3944
Published April 01, 2014 by SAE International in United States
Citation: Asad, U. and Tjong, J., "Transient Build-up and Effectiveness of Diesel Exhaust Gas Recirculation," SAE Int. J. Engines 7(1):172-182, 2014, https://doi.org/10.4271/2014-01-1092.
Modern diesel engines employ a multitude of strategies for oxides of nitrogen (NOx) emission abatement, with exhaust gas recirculation (EGR) being one of the most effective technique. The need for a precise control on the intake charge dilution (as a result of EGR) is paramount since small fluctuations in the intake charge dilution at high EGR rates may cause larger than acceptable spikes in NOx/soot emissions or deterioration in the combustion efficiency, especially at low to mid-engine loads. The control problem becomes more pronounced during transient engine operation; currently the trend is to momentarily close the EGR valve during tip-in or tip-out events. Therefore, there is a need to understand the transient EGR behaviour and its impact on the intake charge development especially under unstable combustion regimes such as low temperature combustion.
This study describes a zero-dimensional EGR model that enables the estimation of transient (cycle-by-cycle) build-up of EGR and the time (engine cycles) required to reach steady-state EGR operation (intake/exhaust concentrations). The model response is tuned to a multi-cylinder engine by using an overall engine system time-constant. The effect of EGR on the cylinder charge has been examined in terms of the intake charge dilution and the excess-air ratio. The intake dilution has been empirically shown to provide a reliable quantitative measure of the EGR effectiveness in reducing NOx emissions. The EGR analysis is validated against a wide range of engine operations.
|Technical Paper||Approach to Estimate Life of Li-Ion Power Battery for Mild Hybrid Application in India|
|Technical Paper||Experimental and Simulation Study to Optimize the Venturi Throat Diameter for Effective Use of EGR Rate to Achieve BSIV|