Effects of Diesel Hydrocarbon Components on Combustion and Emissions in a Heavy-Duty Diesel Engine

An in-depth study of the effects of diesel hydrocarbon components on diesel engine performance can help achieve efficient and clean combustion and provide guidance for improving commercial diesel components. In this paper, the −20 # automotive diesel (D100, the freezing point is not less than −20°C) sold in China was used as the base fuel, and 5%, 10%, and 15% aromatics solvent oils (named A5, A10, A15), 5%, 10%, and 15% diesel from indirect coal liquefaction (DICL5, DICL10, DICL15), and 60%, 70%, and 90% hydrogenated catalytically cracked diesel (HCD60, HCD70, HCD90) were added into D100 by volume fraction, respectively, and the physicochemical properties of mixed fuels were kept to meet the commercial diesel standard. The effects of different diesel hydrocarbon components on combustion characteristics, fuel economy, and emissions of heavy-duty diesel engines under the World harmonized steady-state cycle (WHSC) were investigated. Results show that A series fuels have the highest heat release rate, combustion pressure, and maximum pressure rise rate compared to D100, while HCD series fuels have the shortest ignition delay and combustion duration. Compared to D100, A series fuels decrease soot and CO emissions at most loads. DICL10, DICL15, and HCD series fuels decrease brake specific fuel consumption (BSFC) and increase nitrogen oxides (NOx) emissions above 50% load. Both DICL and HCD series fuels reduce HC emissions below 50% load while increasing HC emissions at 100% load. Based on WHSC’s weighted BSFC and emission results, compared to D100, adding aromatics increases BSFC, hydrocarbons (HC), and NOx emissions but reduces soot and CO emissions. Adding higher paraffins (DICL10, DICL15) and cycloalkanes reduce BSFC, soot, HC, and CO emissions, but increase NOx emissions. DICL10 has the best comprehensive reduction effect on BSFC and emissions. Compared with D100, BSFC, soot, HC, and CO emissions of DICL10 are decreased by 1.61%, 40.39%, 45.29%, and 19.51%, respectively, while NOx emissions are increased by 14.28%. In addition, the DICL10’s 100 km fuel consumption is reduced by up to 3.60%.