Feasibility study on application of low-grade fuels (naphtha and ethanol) in blended-fuel- and convergence-combustion modes

Since electrification is difficult in the sector where heavy-duty diesel engines are used, research is still needed to improve air pollutants. In addition, it is necessary to search for fuel to solve the depletion of fossil fuels and to study appropriate combustion methods according to fuel characteristics. In this study, naphtha or ethanol was selected as a fuel that could replace a certain fraction of diesel fuel. This study aims to compare both methods of supplying and burning naphtha or ethanol with diesel. The method of supplying naphtha or ethanol blended directly with diesel and burning it is suitable for naphtha. Since ethanol has a lower heating value, blended-fuel combustion mode with ethanol reduces IMEPnet. However, this method of separate injection and burning is only suitable for ethanol. When naphtha is utilized in convergence combustion, a wetting phenomenon arises due to its limited evaporation characteristics, leading to a reduction in fuel delivery. The NOx reduction rate was higher in the convergence combustion mode than that in the blended-fuel combustion mode. However, both the combustion methods led to an increase in the THC and CO emissions.