Pyston system definition and verification of Natural Gas engine for truck application

The work of the thesis has been focused on the study of the PCU system, which consists of piston, piston rings and liner, of a 12,9 L 6-cylinders in-line natural gas internal combustion engine for heavy duty application. The final goal is the evaluation of the friction of the PCU system and blow-by flowrate through a predictive model implemented in the program GT Power representative of a single crank. The thesis is organized starting from the current scenario about air pollution and emission regulations with a theoretical description of the phenomenon and the part of the engine contributing to friction and blow-by, with a focus on the part modeled in GT Power. At the beginning is also introduced the system engineering discipline, whose guidelines have been followed to verify the targets of friction and blow-by. The results obtained in GT Power was analyzed comparing different alternatives of piston rings provided by the supplier evaluating their impact in terms of friction and subsequently the weight in CO2 emissions in the VECTO cycle used for homologation. Some of the results have been compared with experimental data from bench test when available.