Exhaust emissions estimation during transient turbocharged diesel engine operation using a two-zone combustion model

A comprehensive, two-zone, transient, diesel combustion model is used to study the performance and exhaust emissions of a turbocharged diesel engine during load transients. Analytical modelling of fuel spray and in-cylinder processes is included, while detailed equations concerning all engine sub-systems describe the phenomena, which diversify transient operation from the steady-state. Demonstrative diagrams are provided for the time histories of nitric oxide (NO) and soot emissions during transient operation, and the main factors affecting their formation are highlighted. Moreover, in-cylinder development of NO concentration and soot density during individual transient cycles is provided and compared with their respective steady-state counterparts. This comparison points out the differences between steady-state and transient operation, as regards exhaust emissions development. The study is expanded with the investigation of load change magnitude and cylinder wall insulation effects oil transient emissions.