Abstract
The present study is focused on the development of a new control-oriented semi-empirical model to predict nitrogen oxide (NOx) emissions in a light-duty diesel engine under both steady-state and transient conditions. The model is based on the estimation of the deviations of NOx emissions, with respect to the nominal engine-calibration map values, as a function of the deviations of the intake oxygen concentration and of the combustion phasing. The model also takes into account the effects of engine speed, total injected quantity, and ambient temperature and humidity. The approach has been developed and assessed on an Fiat Powertrain Technologies (FPT) Euro VI 3.0 L diesel engine for light-duty applications, in the frame of a research project in collaboration with FPT Industrial. The model has also been tested on a rapid prototyping device, and it was shown that it requires a very short computational time, thus being suitable for implementation on the Engine Control Unit (ECU) for real-time NOx control tasks.
Highlights
nitrogen oxide (NOx) emission control constitutes a critical issue in modern diesel engines, considering the more and more stringent emission regulations
With reference to the case in which MFB50 is extracted from the in-cylinder pressure trace, the values of MFB50 used in the model are the result of the average over the last consecutive 100 cycles for the steady-state tests, while they derive from a cycle-by-cycle acquisition in the transient tests
NOx emissions taking into account the expanded uncertainty 50((a) MFB50 from from heat release model); (b,d) statistical distribution of the relative pressure sensor, (c) sensor, (c) MFB50 from heat release model); (b,d) statistical distribution of the relative expanded from heat release model); (b,d) statistical distribution of the relative pressure (c) MFB
Summary
NOx emission control constitutes a critical issue in modern diesel engines, considering the more and more stringent emission regulations. Several techniques have been investigated to control NOx emissions from diesel vehicles, which include the use of more and more efficient after-treatment devices, such as, Lean NOx Traps (LNTs) or Selective Catalytic Reduction (SCR) devices [2], as well as the limitation of in-cylinder NOx formation. With reference to the latter technique, innovative combustion modes have recently been explored, such as the Premixed Charge Compression Ignition (PCCI) mode or the Homogeneous. These techniques are not yet fully adopted in commercial vehicles, and additional research efforts are still needed in order to fully exploit their potential
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