Comparison of Gasoline (ULG), 2,5-Dimethylfuran (DMF) and Bio-Ethanol in a DISI Miller Cycle with Late Inlet Valve Closing Time

Using Miller cycle is one of the effective ways to improve the SI engine efficiency and reduce CO₂ emissions. While much information is in the literature about the research on Miller cycle for gasoline engines, very limited experimental data have been published with respect Miller cycle when the engine is fueled by bio-fuels and this has been considered in the present study of 2,5-dimethylfuran (DMF) which is a new promising biofuel candidate. In this research, a single-cylinder naturally aspirated direct-injection spark-ignition (DISI) engine was modified to operate under the Miller cycle condition by using late inlet valve closing strategy. The engine tests were conducted with a compression ratio of 11.5 at the engine speed of 1500 rpm for three different fuels, gasoline, DMF and bio-ethanol. The effect of fuel properties on the performance and emissions of the engine was examined. The test results indicate that gasoline-fueled Miller cycle has higher engine efficiency by up to 6.9% at 7.5 bar IMEP and lower emissions compared with the Otto cycle under the same conditions but the improvement is not evident with bio-ethanol or DMF. Higher compression ratios and/or boosting are needed for bio-ethanol and DMF to take the advantage of Miller cycle. NO level is a concern when using the LIVC Miller cycle and EGR however is an effective method to control the emission.