A Study on Combustion Parameters in an Automotive Turbocharged Diesel Engine

Abstract

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 to evaluate a large set of combustion parameters. Available data were referred to different tests in three part load operating conditions, focused on High Pressure 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 enlarging the information content of measured in-cylinder pressure diagrams. Several linear correlations were then defined, linking engine operating, energy and environmental quantities to combustion parameters, useful for the analysis and modeling 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.

Influence of Fuel Injection, Turbocharging and EGR Systems Control on Combustion Parameters in an Automotive Diesel Engine

“…In the previous step of this study [1], the relationship between average engine quantities and combustion parameters were developed referring to test Sets 1 and 2. The main targets were the validation of available data through expected correlations and the prediction of further links, which may be applied for engine and sub-systems modelling, the design of experimental campaigns and the definition of control strategies.…”

“…The selection of working conditions referred to part load engine operation, considering low and medium levels of brake mean effective pressure (bmep) and rotational speed n (respectively 2, 5 and 8 bar; 1500, 2000 and 2500 rpm). These points are representative of type approval and real-world driving conditions in urban and extra-urban modes for cars fitted with the tested engine [1].…”

“…While a previous paper [1] was focused on the influence of the EGR rate and variable nozzle turbine (VNT) control on engine quantities, pressure diagrams and combustion parameters, this paper refers to whole sets of experimental campaigns, thus including the effects of rail pressure management. A further goal was to identify similarities in the influence of the three sub-systems control on observed trends of measured parameters.…”

Instantaneous in-Cylinder Volume Considering Deformation and Clearance due to Lubricating Film in Reciprocating Internal Combustion Engines

“…In the same way, the variation in the ROHR for different engine speeds was calculated (and shown in Figure 15) and it is emphasized that the best result is obtained when the model including deformation and clearance proposed in the actual research is used. Taking into account previous research [15,[33][34][35] and the fact that there is a relation between the volume of the combustion chamber and the inside temperature reached, it is evident the influence of the volume variation due to pressure and clearances on the thermodynamic modeling [36]. Additionally, diagnostics thermodynamic modeling shows variations in the rate of heat release due to changes in the compression ratio, which in turn is caused by the change of volume in the combustion chamber.…”

“…As a result of the above, it is assumed that the behavior of the lubricating film is a factor required to calculate the overall variation of the free height of the piston, and hence the instantaneous volume variation in the combustion chamber. Taking into account previous research [15,[33][34][35] and the fact that there is a relation between the volume of the combustion chamber and the inside temperature reached, it is evident the influence of the volume variation due to pressure and clearances on the thermodynamic modeling [36].…”