A Study on Combustion Parameters in an Automotive Turbocharged Diesel Engine

A wide experimental database on indicated pressure diagrams measured on a turbocharged diesel engine, equipped with high and low pressure exhaust gas recirculation (EGR) circuits and a variable nozzle turbine (VNT), was processed in order to evaluate a large set of combustion parameters. Available data were referred to different tests in three part load operating conditions, focused on HP EGR trade-off and the development of integrated control strategies for EGR and turbocharging systems aiming at NOX and fuel consumption reduction. According to their definition, combustion parameters were derived from pressure diagrams, its first derivative and heat release curves. Their calculation allowed to enlarge the information content of measured in-cylinder pressure diagrams. A number of linear correlations were then defined, linking engine operating, energy and environmental quantities to combustion parameters, useful for the analysis and modelling of in-cylinder processes and engine behavior. The influence of testing conditions on these relationships was also analyzed, referring to the investigated operating modes and the adoption of open and closed loop scheme for VNT management. Finally, general correlations were defined, linking NOX and soot emissions to selected quantities.