Effect of reformed EGR on the performance and emissions of a diesel engine: A numerical study

Abstract

Diesel fueled CI engine is a widely accepted prime over owing to its high fuel conversion efficiency and load bearing capabilities. However, its use is constrained by high NOx and PM emissions. To address the issue of effective abatement of these emissions, an attempt is made in the present work and work reports numerical studies on the effect of reformed exhaust gas recirculation (REGR) of a single cylinder compression ignition engine fueled with diesel. For this purpose, a computational study using ECFM-3Z (extended coherent flame model-3 zones) model, ES-ICE and STAR-CD code has been carried out. Considering a sector model of an engine cylinder, in-cylinder pressures and temperatures Soot and Nitrous oxides (NOX) emission characteristics are observed. The studies include numerical experiments on various levels of REGR with two different compositions and comparison with their respective exhaust gas recirculation (EGR) levels at medium load conditions (write specific amounts). The REGR trends of combustion and emissions are significantly modified (is it correct here) when compared to EGR levels. Peak pressures for all REGR cases are higher than those for corresponding EGR levels. A maximum of 12.1% increase in peak pressure is found for 15% REGR (25%H2-0%CO) case than that for 15% EGR. Except for 25% REGR cases, Piston work for 5% REGR and 15% REGR cases is found to be higher than that for respective EGR because of H2 combustion dominance over exhaust gases dilution. Soot emissions for all REGR cases are observed lower than those for corresponding EGR cases. A maximum reduction of 12.73% is noted for 15% REGR (25%H2-0%CO) case than that for 15% EGR. Keywords: EGR, REGR, Piston work, NOX emissions, Soot emissions