MAHLE Advanced EGR Systems for Commercial Diesel Engines to Meet Future Emission Demands

2007 ◽  
Author(s):  
Marco Warth ◽  
Boris Lerch ◽  
Adam Loch ◽  
Alfred Elsaesser
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Intake Manifold ◽  
Emission Regulations ◽  
Technical Advances ◽  
Future Emission ◽  
Heavy Duty Diesel ◽  
Low Torque ◽  
Key Aspects ◽  
Fast Acting

Given the ever more stringent emission regulations modern diesel engines undergo these days, the need for advanced EGR systems becomes crucial in all major applications, in particular on- & off-road commercial diesel engines. One of the key aspects of these so-called advanced EGR systems thereby is to reliably provide the engine with the appropriate, high amounts of EGR over the entire range of operating conditions. Whereas common systems are either optimized for low-torque/low-speed operating conditions, or a narrow range around one specific engine speed, the advanced systems aim to both cover the entire operating range and significantly increase the current level of EGR. The advanced EGR systems developed at MAHLE make use of two types of fast acting devices in a modular approach. Depending on the engine size/layout and the amount of EGR needed, the devices are either placed directly in the EGR line or the intake manifold. Using the latest technical advances in mechatronics, the oscillating valves can be opened or closed within less than 3ms, which makes it not only possible to accurately control the amount of EGR fed back into the engine, it also allows to boost the amount of EGR using the exhaust pressure oscillations. In addition to these oscillating valves, rotational flaps have been developed to significantly reduce the complexity of the systems, while still offering similar benefits in terms of EGR rates and variability. Shown hereafter are the results from thorough investigations conducted on both European and US heavy-duty diesel engines. Focusing on some of the most common engine characteristics, such as EGR rates, emissions of nitrogen oxide and fuel consumption, significant benefits can be seen using the newly developed technologies. Compared to conventional measures, such as increased exhaust backpressure and/or constant charge-air throttling, the advanced systems prove to be both more efficient and flexible in terms of EGR rates, as well as beneficial regarding some of the most important engine characteristics.

Modeling heavy-duty diesel engines using tabulated kinetics in a wide range of operating conditions

2020 ◽  
pp. 146808741989616 ◽  
Author(s):  
Qiyan Zhou ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Gilles Hardy ◽  
Xingcai Lu
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Scalar Dissipation ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Variable Model ◽  
Progress Variable ◽  
Wide Range ◽  
Heavy Duty Diesel ◽  
Operating Points

Fast and high-fidelity combustion models including detailed kinetics and turbulence chemistry interaction are necessary to support design and development of heavy-duty diesel engines. In this work, the authors intend to present and validate tabulated flamelet progress variable model based on tabulation of laminar diffusion flamelets for different scalar dissipation rate, whose predictability highly depends on the description of fuel–air mixing process in which engine mesh layout plays an important role. To this end, two grids were compared and assessed: in both grids, cells were aligned on the spray direction with such region being enlarged in the second one, where the near-nozzle and near-wall mesh resolution were also improved, which is expected to better account for both spray dynamics and flame–wall interaction dominating the combustion process in diesel engines. Flame structure, in-cylinder pressure, apparent heat release rate, and emissions for different relevant operating points were compared and analyzed to identify the most suitable mesh. Afterwards, simulations were carried out in a heavy-duty engine considering 20 operating points, allowing to comprehensively verify the validity of tabulated flamelet progress variable model. The results demonstrated that the proposed approach was capable to accurately predict in-cylinder pressure evolution and NO x formation across a wide engine map.

Assessment of a Low-Throughput Predictive Model for Indicated Cycle, Combustion Noise and NOx Calculation in Diesel Engines in Steady-State and Transient Operations

2012 ◽  
Author(s):  
Andrea Emilio Catania ◽  
Roberto Finesso ◽  
Ezio Spessa
Keyword(s):  
Steady State ◽  
Diesel Engines ◽  
Operating Conditions ◽  
Combustion Noise ◽  
Intake Manifold ◽  
Combustion Model ◽  
Data Set ◽  
Automotive Engine ◽  
Engine Calibration ◽  
Transient Operations

A predictive zero-dimensional low-throughput combustion model that was previously developed by the authors has been refined and applied to a EURO V diesel automotive engine. The model is capable of simulating, in real time, the time-histories of the HRR (Heat Release Rate), in-cylinder pressure, in-cylinder temperatures and NOx (nitrogen oxides) concentrations, on the basis of a few quantities estimated by the ECU (Engine Control Unit), such as the injection parameters, the trapped air mass, the intake manifold pressure and temperature. It has been developed for model-based feedforward control purposes in DI (Direct Injection) diesel engines featuring an advanced combustion system or new combustion-mode concepts, such as LTC/PCCI (Low Temperature Combustion/Premixed Charge Compression Ignition) engines. In the present work, the model has been assessed in detail by analyzing a wide set of experimental engine data that were acquired during the engine calibration phase. The experimental data set has been defined according to the DoE (Design of Experiment) methodology currently used for engine calibration purposes, and applied to six ‘key-points’ that are representative of engine working operations during an NEDC (New European Driving Cycle) for a D-class passenger car. Different injection strategies (pilot-main, double pilot-main; pilot-main-after; double pilot-main-after) have been considered for each key point, and all the main engine operating parameters (rail pressure, injected quantities, boost level, intake temperature, EGR rate,…) have been included in the DoE variation list. Therefore, about 1000 steady-state engine operating conditions have been investigated. In addition, several NEDC driving cycles have been realized with the engine installed on a dynamic test rig, and the combustion parameters and emission levels have continuously been measured during the transient operations. The model has been applied to all the investigated conditions. It has shown excellent accuracy in estimating the values of the main combustion parameters, and a good matching between the calculated and predicted NOx concentrations was found, for both steady-state and transient operations.

Multiple Combustion Stages Inside a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark-Ignition Operation

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Intake Manifold ◽  
Lean Burn ◽  
Spark Timing ◽  
Before And After ◽  
Heavy Duty Diesel ◽  
The One

Abstract Converting existing diesel engines to natural-gas (NG) spark-ignition (SI) operation can reduce the dependence on oil imports and increase energy security. NG-dedicated conversion can be achieved by the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Previous studies indicated that lean-burn NG inside the traditional diesel chamber (i.e., a bowl-in-piston geometry) is a two-stage combustion (i.e., a fast burn inside the bowl followed by a slower burn inside the squish). However, a triple-peak apparent heat release rate (AHRR) was seen at specific operating conditions (e.g., advanced spark timing (ST) at medium load and engine speed), suggesting that one of the two combustion stages may separate again. Specifically, the burn inside the squish region divided in two events before and after top dead center (TDC). This was due to the different flow motion inside the squish during the compression stroke compared to the one in the expansion stroke, which affected the combustion environments. The result was the apparition of two close peaks in pressure trace, which suggest larger gradients in pressure and temperature than at a more delayed ST. In addition, the phasing and magnitude of three peaks of the heat release changed cycle-to-cycle. As an advanced ST is the usual strategy used in lean-burn SI combustion, understanding phenomena such as the one presented here can be important for reducing engine-out emissions and increase engine efficiency.

scholarly journals Calculation of Intake Oxygen Concentration through Intake CO2 Measurement and Evaluation of Its Effect on Nitrogen Oxide Prediction Accuracy in a Heavy-Duty Diesel Engine

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 342
Author(s):  
Roberto Finesso ◽  
Omar Marello
Keyword(s):  
Diesel Engine ◽  
Oxygen Concentration ◽  
Control Unit ◽  
Absolute Error ◽  
Operating Conditions ◽  
Intake Manifold ◽  
Heavy Duty ◽  
Input Quantity ◽  
Heavy Duty Diesel Engine ◽  
Heavy Duty Diesel

A new procedure, based on measurement of intake CO2 concentration and ambient humidity was developed and assessed in this study for different diesel engines in order to evaluate the oxygen concentration in the intake manifold. Steady-state and transient datasets were used for this purpose. The method is very fast to implement since it does not require any tuning procedure and it involves just one engine-related input quantity. Moreover, its accuracy is very high since it was found that the absolute error between the measured and predicted intake O2 levels is in the ±0.15% range. The method was applied to verify the performance of a previously developed NOx model under transient operating conditions. This model had previously been adopted by the authors during the IMPERIUM H2020 EU project to set up a model-based controller for a heavy-duty diesel engine. The performance of the NOx model was evaluated considering two cases in which the intake O2 concentration is either derived from engine-control unit sub-models or from the newly developed method. It was found that a significant improvement in NOx model accuracy is obtained in the latter case, and this allowed the previously developed NOx model to be further validated under transient operating conditions.

scholarly journals Particulate emissions of heavy duty diesel engines measured from the tailpipe and the dilution tunnel

2021 ◽  
pp. 105799
Author(s):  
Sheng Su ◽  
Tao Lv ◽  
Yitu Lai ◽  
Jinsong Mu ◽  
Yunshan Ge ◽  
...  
Keyword(s):  
Diesel Engines ◽  
Particulate Emissions ◽  
Heavy Duty ◽  
Heavy Duty Diesel
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