A New Model for Matching Advanced Boosting Systems to Automotive Diesel Engines

Abstract

Boosting technologies have been key enablers for automotive engines development through downsizing and downspeeding. In this situation, numerous multistage boosting systems have appeared in the last decade. The complexity arising from multistage architectures requires an efficient matching methodology to obtain the best overall powertrain performance. The paper presents a model aimed to choose the best 2-stage boosting system architecture able to meet required criteria on boosting pressure, EGR ratios for both short and long route loops while respecting the engine thermo-mechanical limits such as in-cylinder pressure, compressor outlet temperature and exhaust manifold temperature. The model includes filling-and-emptying 0D elements together with mean value. The engine model is set in a way that, for given requirements and boosting system layout, calculates in seconds if the requirements will be achieved and the position of variable geometry, waste-gate, EGR and bypass valves. The model is thus inversed thanks to a new representation of turbine maps that converts the classical iterative matching procedure in straight forward. The model can be also used in a predictive manner to calculate the engine transient response. The model has been calibrated to 3 different turbocharged diesel engines. The model gives good results provided that wave effects are not important. This is the case of compact exhaust manifolds, typically used in turbocharged diesel engines, below 3500 rpm. Tuned intake air lines can be taken into account through a tuning parameter affecting boosting pressure. An example is given in the paper for the matching procedure in a 2-stage, double route EGR, including steady and transient results.

Review of engine control-oriented combustion models

“…In some SI and CI engines, a single low pressure-EGR (LP-EGR) loop is used 52,53 or combined with HP-EGR to form a dual-loop EGR system. 54,55 Grondin et al 54 provides mean mass flow formulae for dual-loop EGR systems below.…”

Effect of boosting system architecture and thermomechanical limits on diesel engine performance: Part-I—Steady-state operation

“…To take into account the effects of mass transfers and accumulations, it includes a control volume for each manifold and each cylinder. 1,3 The cylinder valves and the high-pressure (HP) EGR valve are simulated by isentropic nozzles, while the ports and the HP EGR pipes are directly included in the volume of their corresponding manifold. Low-pressure (LP) and HP EGR systems were analyzed under three different EGR rates: 0% (without EGR), 15% (Euro VII objectives) and 30% (strong EGR constraint).…”

“…The most promising boosting systems to increase the performance of automotive downsized/ downspeeded engines are sequential serial two-stage turbocharging, mechanical auxiliary supercharging and electric boosters. 3 Therefore, the effect of these boosting systems used in two-stage configuration on engine parameters is important to be characterized.…”

Modelling the Exhaust Gas Recirculation Mass Flow Rate in Modern Diesel Engines

“…Intake manifold pressure is the logical choice for the downstream pressure. Most modeling work found in the literature uses exhaust pressure and exhaust temperature respectively as the upstream pressure and temperature inputs to the model [2,3,7,21,22,25,26,28]. If the exhaust pressure and exhaust temperature are not available, a black box model can be developed to provide these variables into the EGR flow rate model [28].…”

“…It is claimed in [24] that it is also possible to estimate the EGR flow rate by applying orifice type flow rate model on the EGR cooler element. This type of EGR flow rate model is also a very important part of Mean Valve Engine Model (MVEM) which is the foundation for fast engine simulation and online optimization [25,26,27].…”