Improving NOx Versus BSFC with EUI 200 Using EGR and Pilot Injection for Heavy-Duty Diesel Engines

Abstract

<div class="htmlview paragraph">An experimental study has been carried out on a single-cylinder pressure-charged engine with a near quiescent combustion system. An improvement in the NO<sub>x</sub>/BSFC trade-off was achieved by two different approaches, namely exhaust gas recirculation and pilot injection.</div> <div class="htmlview paragraph">Without EGR, a reference EUI-200 system with 1900 bar peak injection pressure gave a low soot particulate level of 0.013 g/bhp h over a simulation of the US FTP cycle. The results with EGR show how higher levels of EGR can be used at more advanced injection timings to give substantially improved NO<sub>x</sub> versus BSFC results compared with timing retard alone. It was possible to reduce the NO<sub>x</sub> from 4.85 to 3.6 g/bhp h for no increase in BSFC over the simulated US FTP cycle and with a total calculated particulate of 0.075 g/bhph.</div> <div class="htmlview paragraph">The results with electronically-controlled pilot injection show improvements in NO<sub>x</sub> versus BSFC, lower NO<sub>x</sub> before HC increase with retard, or reduced combustion noise at certain test modes. Simulated US FTP cycle results show that a pilot injection strategy could be used to reduce NO<sub>x</sub> from 4.94 to 3.82 g/bhp h for a 6.6% increase in BSFC compared with an increase of 10% in BSFC if timing retard alone is used.</div>