Reduction of transient NOx emissions based on set-point adaptation of real-time combustion control for light-duty diesel engines

A novel decentralized control architecture is developed based on a feedback from the pressure difference across the engine which is responsible for the pumping losses and the exhaust gas recirculation (EGR) flow in diesel engines. The controller is supplemented with another feedback loop based on NOx emissions measurement. Aiming for simple design and tuning, the two control loops are designed and discussed: one manipulates the variable geometry turbine (VGT) actuator and the other manipulates the EGR valve. An experimentally validated mean-value diesel engine model is used to analyze the best pairing of actuators and set points. Emphasis is given to the robustness of this pairing based on gain changes across the entire operating region, since swapping the pairing needs to be avoided. The VGT loop is designed to achieve fast cylinder air charge increase in response to a rapid pedal tip-in by a feedforward term based on the real-time derivative of the desired boost pressure. The EGR loop relies on a feedback measurement from a NOx sensor and a real-time estimation of cylinder oxygen ratio, χcyl. The engine model is used for evaluating the designed controllers over the federal test procedure (FTP) for heavy duty (HD) vehicles. Results indicate that the control system meets all targets, namely fast air charge and χcyl control during torque transients, robust NOx control during steady-state operation, and controlled pumping losses in all conditions.

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In-cylinder pressure sensor–based NOx model for real-time application in diesel engines

International Journal of Engine Research ◽

10.1177/1468087417703201 ◽

2017 ◽

Vol 19 (3) ◽

pp. 293-307 ◽

Cited By ~ 3

Author(s):

Hoon Cho ◽

Brien Fulton ◽

Devesh Upadhyay ◽

Thomas Brewbaker ◽

Michiel van Nieuwstadt

Keyword(s):

Real Time ◽

Diesel Engines ◽

Pressure Measurements ◽

Cylinder Pressure ◽

Performance Bounds ◽

Dimensional Model ◽

Heavy Duty ◽

Light Duty ◽

Proposed Model ◽

Real Time Application

A real-time implementable, zero-dimensional model for predicting engine-out emissions of nitrogen oxides using in-cylinder pressure measurements is developed. The model is an extension of existing works in open literature that align well with the objectives of real-time implementation. The proposed model uses a simplified Zeldovich NOx mechanism that uses combustion-related parameters derived from simplified thermodynamic and combustion sub-models. The performance of the model is discussed for both a heavy-duty and a light-duty diesel engines. The model behavior is evaluated under input uncertainty so as to provide realistic performance bounds.

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Real-time NOx estimation in light duty diesel engine with in-cylinder pressure prediction

International Journal of Engine Research ◽

10.1177/14680874211015780 ◽

2021 ◽

pp. 146808742110157

Author(s):

Youngbok Lee ◽

Seungha Lee ◽

Kyoungdoug Min

Keyword(s):

Prediction Model ◽

Real Time ◽

Pressure Sensor ◽

Design Stage ◽

Lean Nox Trap ◽

Nox Emissions ◽

Cylinder Pressure ◽

Estimation Model ◽

Light Duty ◽

Light Duty Vehicle

Recently, there have been numerous efforts to cope with automotive emission regulations. Various strategies to reduce engine-out NOx emissions and proper after-treatment systems, such as selective catalytic reduction (SCR) and lean NOx trap (LNT), have been taken into account in the engine research field. In this study, real-time engine-out NOx prediction model was established where zero-dimensional NO and NO2 models were combined with in-cylinder pressure model. During the procedure for estimating NO and NO2 (NOx), a real-time prediction model of in-cylinder pressure was applied so that the inputs to the NOx prediction model could be provided only by the data acquired from the engine control unit (ECU). This implies that an in-cylinder pressure sensor is not necessarily required to properly predict the engine-out NOx in real time. The real-time NOx estimation model was validated through the worldwide harmonized light-duty vehicle test cycle (WLTC) without a pressure sensor, and the total NOx error during the mode was comparable with the total NOx error of the portable NOx sensor. This real-time NOx estimation model can ultimately contribute to minimizing tail-pipe NOx emissions by influencing both emission calibration at the engine design stage and the management of NOx after-treatment systems where NOx conversion efficiency is heavily affected by the NO2/NO ratio.

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A control-oriented real-time semi-empirical model for the prediction of NOx emissions in diesel engines

Applied Energy ◽

10.1016/j.apenergy.2014.05.046 ◽

2014 ◽

Vol 130 ◽

pp. 265-279 ◽

Cited By ~ 40

Author(s):

Stefano d’Ambrosio ◽

Roberto Finesso ◽

Lezhong Fu ◽

Antonio Mittica ◽

Ezio Spessa

Keyword(s):

Real Time ◽

Empirical Model ◽

Diesel Engines ◽

Nox Emissions ◽

Semi Empirical

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Decentralized Feedback Control of Pumping Losses and NOx Emissions in Diesel Engines

Volume 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical Development ◽

10.1115/icef2017-3672 ◽

2017 ◽

Author(s):

Rasoul Salehi ◽

Jason Martz ◽

Anna Stefanopoulou ◽

Bruce Vernham ◽

Lakshmidhar Uppalapati ◽

...

Keyword(s):

Real Time ◽

Diesel Engines ◽

Test Procedure ◽

Time Derivative ◽

Time Estimation ◽

Mean Value ◽

Boost Pressure ◽

Nox Emissions ◽

Control Loops ◽

Engine Model

A novel decentralized control architecture is developed based on a feedback from the pressure difference across the engine which is responsible for the pumping losses and the Exhaust Gas Recirculation (EGR) flow in diesel engines. The controller is supplemented with another feedback loop based on NOx emissions measurement. Aiming for simple design and tuning, the two control loops are designed and discussed; one manipulates the Variable Geometry Turbine (VGT) actuator and the other manipulates the EGR valve. An experimentally validated mean-value diesel engine model is used to analyze the best pairing of actuators and set points. Emphasis is given to the robustness of this pairing based on gain changes across the entire operating region, since swapping the pairing needs to be avoided. The VGT loop is designed to achieve fast cylinder air charge increase in response to a rapid pedal tip-in by a feedforward term based on the real-time derivative of the desired boost pressure. The EGR loop relies on a feedback measurement from a NOx sensor and a real-time estimation of cylinder oxygen ratio, χcyl. The engine model is used for evaluating the designed controllers over the federal test procedure (FTP) for heavy duty vehicles. Results indicate that the control system meets all targets, namely fast air charge and χcyl control during torque transients, robust NOx control during steady state operation and controlled pumping losses in all conditions.

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