Project Details
Projekt
Control of quasi-homogeneous combustion in diesel engines using fully-variable injection
Subject Area
Energy Process Engineering
Term
since 2016
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 277012063
The main goal of this subproject is the further development of the Premixed Charge Compression Ignition (PCCI) diesel combustion process using optimization-based control. For this, the entire injection process and the entire burn function are used as continuous actuation and control variables, respectively. In order to be able to establish a cycle-to-cycle, ideally also an in-cycle control, these variables must be described by physically-based, low-dimensional parameterizations. In the first funding period, quantitative models based on a combination of unsupervised and supervised machine learning were developed and validated from experimental data for various multiple-injection patterns including the so-called alpha-process with limiting cylinder pressure rise rate. With data from TP6, models for reaction kinetics were developed that serve as the basis for 3D CFD simulations and model reduction. In order to apply the control of various performance parameters over a wide load range and even for transient operation conditions, a combination of low-temperature combustion (LTC) and alpha-process will be implemented, and an in-cycle control approach will be established. The basis for this is a fast and precise model to describe the influence of the very early heat release on the performance parameters. The analysis of the interaction between LTC and limited cylinder pressure rise rates as well as its effect on the performance parameters will first be carried out using experimentally obtained data spaces. This forms the basis for the description of the relationships injection/burn function and burn function/emissions by incorporation of semi-physical, reaction-kinetics based modeling approaches. For the application in real-time combustion control, these will be transformed into a low-dimensional parameterization. Here, the uniqueness of the pressure curve analysis for the description of the LTC will be critically examined and the potential of ion current measurements explored as a complementary parameter or even to substitute the pressure curve analysis. The reaction-kinetics based sensitivities of the very early ignition phase will be examined, which are of great importance in low-temperature combustion due to the increasing temporal proportion of the chemical ignition delay. Kinetic models, which also include the ion current and pollutant formation mechanisms, will be developed for this and other sub-projects, and used, for instance, in the reduced order models. CFD simulations will be used to identify and explain correlations and corresponding physical relationships will be derived to support the simplified model. Work on the detailed kinetics of LTC, pollutant emissions, and ion current characterization will be carried out in collaboration with TP6. The simplified models will be validated in cooperation with TP7 and with the single-cylinder research engine.
DFG Programme
Research Units
