Experimental investigation of the effects of fuel characteristics on high efficiency clean combustion in a light-duty diesel engine

An experimental study was performed to understand fuel property effects on low temperature combustion (LTC) processes in a light-duty diesel engine. These types of combustion modes are often collectively referred to as high efficiency clean combustion (HECC). A statistically designed set of research fuels, the Fuels for Advanced Combustion Engines (FACE), were used for this study. Engine conditions of 1500rpm, 2.6bar BMEP was chosen for investigating fuel property effects on HECC operation in a GM 1.9-L common rail diesel engine. The FACE fuel matrix includes nine combinations of fuel properties including cetane number (30 to 55), aromatic content (20 to 45%), and 90% distillation temperature (270 to 340°C). HECC operation was achieved with high levels of exhaust gas recirculation (EGR) and adjusting injection parameters, such as higher fuel rail pressure and single injection event, which is also known as premixed charge compression ignition (PCCI) combustion. Engine performance, pollutant emissions, and details of the combustion process are discussed in this paper. Cetane number (CN) was found to significantly affect the combustion process with variations in the start of injection (SOI) timing, which revealed that the ranges of SOI timing for HECC operation and the PM emission levels were distinctively different between high CN (55) and low CN fuels (30). Low CN fuels showed comparable levels of regulated gas emissions with high CN fuels and had an advantage in particulate matter (PM) emissions.