Potentials of Air-EGR Dilution for Improving Performance of a High Compression Ratio Spark-Ignition Engine Fueled with Methanol

摘要

The effects of air and exhaust gas recirculation (EGR) dilution of a spark ignition engine fueled with methanol under different loads were studied by experiment in this paper. Such as ignition delay, combustion center (CA50), IMEP, break thermal efficiency (BTE) and other parameters were investigated to assess the combustion performance. And discussed in depth the balance between NOx emissions and economic performance represented by brake specific fuel consumption (BSFC). The results showed that combustion progress such as ignition delay, combustion duration and CA50 were more sensitive on the changes of EGR, introducing EGR under the same dilution rate prolonged combustion process. Air-EGR dilution showed the best improvement of IMEP and break thermal efficiency, except the optimal area, increasing EGR rate will decreased IMEP and BTE. Air-EGR dilution strategy showed the best improvement on BSFC than air dilution than EGR dilution. Under light load and high load, when the lowest BSFC was obtained, NOx emissions were less than 0.5 g/kWh with air-EGR dilution strategy.