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A novel 1D co-simulation framework for the prediction of tailpipe emissions under different IC engine operating conditions.

Aristotle University of Thessaloniki-Zissis Samaras, Grigorios Koltsakis
EMPA-Patrik Soltic, Panayotis Dimopoulos Eggenschwiler, Viola Papetti, Jakub Rojewski PhD
  • Technical Paper
  • 2019-24-0147
To be published on 2019-08-15 by SAE International in United States
The prediction of the pollutants emitted by internal combustion engines during driving cycles has been a challenge since the introduction of the emission regulation legislation. During the last decade, along with the more tightening limits and increased public concern about the matter of air quality, the possibility of simulating various driving tests with cost effective computing facilities has become a key feature for modern simulation codes. Many 1D simulation tools are available on the market, offering real time models capable of achieving the simulation of any driving cycle in limited time frames. These approaches are based on the extreme simplification of the engine geometry and on the adoption of engine maps, which, for any engine operating condition, give the engine output in terms of power, or torque, and of exhaust gas composition. Specific fluid dynamic models are used to track the composition along the exhaust system and, with the aid of ad-hoc modules, to evaluate the conversion efficiency of after-treatment devices, such as TWC, GPF, DPF, DOC, SCR and so on. This work is based…
 

Experimental and Computational Investigation of Particle Filtration Mechanisms in Partially Damaged DPFs

University of Thessaly-Onoufrios Haralampous, Marios Mastrokalos, Foteini Tzorbatzoglou, Chris Dritselis
  • Technical Paper
  • 2019-24-0149
To be published on 2019-08-15 by SAE International in United States
Since September 2018 new threshold limits are applied in the European Union for On-Board Diagnosis (OBD) of particulate mass (PM) leakage. OBD systems are obliged to detect exhaust system malfunctions that account to 2.5 times higher PM emissions compared to the type approval limit. Often the malfunction is located in the Diesel Particulate Filter (DPF), which might suffer substrate crack or melting during harsh regeneration events. In addition, DPF systems have become a tampering target, usually to avoid the high cost of replacement or lower fuel consumption. In this context, understanding the filtration mechanisms in partially damaged DPFs can facilitate the assessment of their environmental effects and the design of exhaust systems with efficient OBD functionality. Two common types of DPF failure are included in this study, namely partial rear plug removal and internal crack development due to uncontrolled regeneration with excessive soot loading. Two respectively damaged SiC filters were loaded with soot on the engine bench applying a specially designed protocol to access the effect of mass flow rate, temperature and deposit loading on…
 

Fuel Consumption and Pollutant Emission Optimization at Part and Full Load of a High-Performance V12 SI Engine by a 1D Model

Automobili Lamborghini Spa-Diego Cacciatore
Lamborghini Automobili-Luca Rizzi
  • Technical Paper
  • 2019-24-0080
To be published on 2019-08-15 by SAE International in United States
Modern internal combustion engines show complex architectures in order to improve their performance in terms of brake torque and fuel consumption. Concerning naturally-aspirated engines, the arrangement of intake and exhaust systems is crucial to get the prescribed target. An optimization of the intake port geometry, together with the selection of a proper valve timing, allow to improve the cylinder filling and hence the performance. This possibility is enhanced by a variable valve timing, even more with unphased intake and exhaust controls. The identification of an optimal calibration strategy at test bench usually requires long and expensive experimental activities. Focusing on these aspects, numerical tools can help to support engine calibration, especially in the early design phases. In the present work, a 12-cylinder naturally aspirated spark ignition engine is investigated. In a preliminary stage, the engine is experimentally tested under full load operation. Main performance parameters, in-cylinder pressure cycles and raw pollutant emissions are measured. The engine is schematized in a one-dimensional model (GT-Power™), where “user routines” are implemented to simulate turbulence, combustion, knock and pollutant…
 
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On the Measurement and Simulation of Flow-Acoustic Sound Propagation in Turbochargers

FEV Europe GmbH-Ralf Stienen
Institute for Combustion Engines, RWTH Aachen University-Hendrik Ruppert, Felix Falke, Stefan Pischinger, Marco Günther
Published 2019-06-05 by SAE International in United States
Internal combustion engines are increasingly being equipped with turbochargers to increase performance and reduce fuel consumption and emissions. Being part of exhaust and intake systems, the turbocharger strongly influences the orifice noise emission. Although 1D-CFD simulations are commonly used for the development of intake and exhaust systems, validated acoustic turbocharger models are not yet state-of-the-art. Consequently, the aim of the paper is the investigation of the turbocharger’s influence on the orifice noise and the development of an accurate 1D-CFD model.The passive acoustic transmission loss was measured for a wide operating range of four turbochargers, including wastegate and VTG-system variations. Low frequency attenuation is dominated by impedance discontinuities, increasing considerably with mass flow and pressure ratio. High frequency transmission loss is generated by destructive interferences in the stator, which depend on the stator mass flow distribution and the turbocharger size.A new generic turbocharger model was developed to model both low frequency impedance discontinuities and high-frequency interferences by linking an idealized stator geometry with potential sources and turbocharger performance maps. In this way, high acoustic and thermodynamic…
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Engine Exhaust Noise Optimization Using Sobol DoE Sequence and NSGA-II Algorithms

Tafe Motors and Tractors Limited-Ishwinder Pal Singh Sethi, Devendra Nene, Anand Shivajirao Patil
Published 2019-06-05 by SAE International in United States
Exhaust muffler is one of the most important component for overall vehicle noise signature. Optimized design of exhaust system plays a vital role in engine performance as well as auditory comfort. Exhaust orifice noise reduction is often contradicted by increased back pressure and packaging space. The process of arriving at exhaust design, which meets packaging space, back pressure and orifice noise requirements, is often manual and time consuming. Therefore, an automated numerical technique is needed for this multi-objective optimization.In current case study, a tractor exhaust system has been subjected to Design of Experiments (DoE) using Sobol sequencing algorithm and optimized using NSGA-II algorithm. Target design space of the exhaust muffler is identified and modeled considering available packaging constrain. Various exhaust design parameters like; length of internal pipes, location of baffles and perforation etc. are defined as input variables. Performance objective of back pressure and sound pressure level has also been defined in simulations workflow.Exhaust orifice noise has been reduced with significant reduction in overall simulations time. The optimal design is achieved satisfying all constrains leading…
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Experimental Analysis of SCR Spray Evolution and Sizing in High-Temperature and Flash Boiling Conditions

SAE International Journal of Fuels and Lubricants

Continental Automotive Systems US Inc., USA-Nic van
Universita degli Studi di Perugia, Italy-Gabriele Brizi, Lucio Postrioti
  • Journal Article
  • 04-12-02-0006
Published 2019-05-16 by SAE International in United States
In the last years, new stringent emission legislation in terms of nitrogen oxides (NOx) has been leading to a massive development of advanced after-treatment systems for diesel engines. Among them, selective catalytic reduction (SCR) technology has proved to be an effective approach for NOx reduction in a wide range of engine operating conditions. In SCR systems, the interaction between diesel exhaust fluid (DEF) and hot exhaust gas is crucial to promote the chemical reactions through which ammonia is produced. Hence, a proper matching between the exhaust pipe architecture and the DEF spray is mandatory for obtaining an adequate SCR efficiency, especially in close-coupled configurations and moderate exhaust gas temperature conditions. To this end, significant benefits could be derived via appropriate SCR injector thermal management, as the spray structure is significantly influenced by the DEF temperature upstream of the injector nozzle. In this article, the results of a spray analysis campaign carried out on a prototype DEF dosing system are presented. The goal of this research is to investigate the influence of both air and DEF…
 

Effect of Exhaust Runner Length, Valve Timing and Lift on the Performance of a Gasoline Engine

University of South Australia-Saiful Bari
Published 2019-04-02 by SAE International in United States
Internal combustion (IC) engine exhaust system can influence the engine’s performance in a significant way. This paper shows that a variable exhaust manifold runner length can improve the engine performance in terms of its output torque by over 10% especially at lower engine speed. Similarly, other exhaust systems such as valve timing and valve lift can improve the performance of the engine in different magnitudes. But when smaller improvements are clubbed together, a significant improvement can be achieved. This paper researches first the exhaust runner length on the engine’s performance. Then, the exhaust valve timing is adjusted to further improve the engine torque produced for the exhaust runner lengths analyzed. Study of a combined effect showed that the runner length requirement shifts slightly as the valve timing is changed. Due to practical limitations foreseen in having longer runner lengths and limitations in the rate of runner length variation, certain areas have to undergo through a region where the torque values are as low as they can be. Though this happens in every single exhaust system…
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Modeling of Engine Aftertreatment System Cooling for Hybrid Vehicles

Linköping University-Olov Holmer, Lars Eriksson
Volvo Group Trucks Technology-Fredrik Blomgren
Published 2019-04-02 by SAE International in United States
Exhaust aftertreatment systems are essential components in modern powertrains, needed to reach the low legislated levels of NOx and soot emissions. A well designed diesel engine exhaust aftertreatment system can have NOx conversion rates above 95%. However, to achieve high conversion the aftertreatment system must be warm. Because of this, large parts of the total NOx emissions come from cold starts where the engine has been turned off long enough for the aftertreatment system to cool down and loose its capacity to reduce NOx. It is therefore important to understand how the aftertreatment cools down when the engine in turned off.Experimental data for a catalyst cool-down process is presented and analyzed. The analysis shows that it is important to capture the spatial distribution of temperatures both in axial and radial directions. The data and analysis are used to design a catalyst thermal model that can be used for model based catalyst temperature monitoring and control.
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Considerations of Periodical Technical Inspection of Vehicles with deNOx Systems

Aurigna Consulting GmbH-Volker Hensel
ETH-Thomas Lutz
Published 2019-04-02 by SAE International in United States
An independent periodical technical inspection (PTI)*) of vehicles is proposed in the last time as a better prevention against increased emissions of the fleet.Several projects focused on the Diesel vehicles (HD & LD) and on the functionality of the exhaust aftertreatment systems as a key element for lowering emissions of a vehicle or machine.The present paper summarizes the results obtained on 3 modern passenger cars Euro 6b (with EGR, DOC, DPF & SCR) during load jumps, representing the heat-up or cool-down behaviour of the exhaust system.The portable devices for PTI were tested together with the stationary measuring systems of the engine laboratory.In the second part of the report, the present knowledge and proposals of supplementary test procedures (like IUC or PTI) were shortly described.It can be stated that the efficiency of the SCR-systems in a short PTI test is visible, and it is possible to quantify it in the positive or negative load jump, if a longer driving period at the constant OP (10 to 15 minutes) is realized in order to attain the stabilization…
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On-Vehicle Fuel Cut Testing for Gasoline Particulate Filter Applications

Corning (Shanghai) Company, Ltd.-Zhihui Lu
Corning Incorporated-Xiangyu Feng, Haixu Liu, Weiwei Li, Suhao He
Published 2019-04-02 by SAE International in United States
With the introduction of a stringent particulate number (PN) limit and real driving emission (RDE) requirements, gasoline particulate filters (GPF) are widely adopted for gasoline engines in Europe and China. The filter collects soot and ash. Like in diesel applications, the collected soot will continuously burn under favorable exhaust conditions. However, at extreme conditions, there could be large amounts of soot build-up, which may induce a highly exothermal event, potentially damaging the filter. Thus, it is important to understand what drives the over-heating in application, and develop counter measures.In this study, an on-vehicle fuel cut (FC) testing procedure was developed. The testing was conducted on two vehicles, one gasoline direct injection (GDI) vehicle and one multiple port injection (MPI) vehicle, with different exhaust systems designs (a close coupled GPF and an under floor GPF) and catalyst coating levels (bare and heavily coated GPFs). Good test repeatability was achieved through carefully controlling testing conditions. Also discussed in the paper is a simple analytical 0D model, which can very well capture the mass transport and reaction fundamentals,…
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