Beijing will implement the 4th stage emission regulations (equivalent to Euro IV) in 2008 ahead of other provinces or cites in China. Beijing Environmental Protection Bureau (EPB) organized petroleum corporations, automobile and engine manufactories as well as research institutes to test the adaptability of the fuels from Chinese refineries to the modern vehicles or engines on the road running conditions in China. In this paper, the effects of diesel fuel quality on combustion and emission of a Euro IV heavy-duty diesel engine as one part of the program were studied to provide technical data to stipulate the feasible diesel fuel standard, which should guarantee modern vehicles or engines to meet the 4th stage regulations.
Eight kinds of diesel fuels with different properties, such as cetane number, distillation temperature (T90) and sulfur content, were tested on a Euro IV Cummins heavy-duty diesel engine with urea SCR after-treatment. Engine power, fuel economy, and ESC cycle emissions (NOx, CO, HC) before and after SCR were measured. The gaseous SO2, total PM and SOF, DS, sulfate in PM were analyzed. Heat release rates were calculated to analyze in-cylinder combustion variation resulting from the changes of the fuel properties.
The test results show that diesel properties have little effect on power, fuel consumption, and heat release rate of the engine; sulfate in PM and gaseous SO2 emission increase linearly with sulfur content; with the increase of cetane number, BSFC and PM decrease slightly, while NOx slightly increases; with the decrease of T90, NOx decreases, and PM shows trend of slight decrease.
Base on the experimental data from ESC cycle, the empirical formula of NOx and PM emissions before SCR changing with the sulfur content, cetane number, aromatics and T90 were obtained using the linear regression method.