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A Methodology for Monitoring Real-World CO2 Emissions Compliance in Passenger Vehicles

Aristotle University of Thessaloniki-Nikiforos Zacharof, Stylianos Doulgeris, Ioannis Myrsinias, Zisimos Toumasatos, Athanasios Dimaratos, Zissis Samaras
European Commission Joint Research-Georgios Fontaras
  • Technical Paper
  • 2020-37-0034
To be published on 2020-06-23 by SAE International in United States
The road transport CO2 emissions reduction scheme in the European Union foresees mandatory targets for passenger vehicles. However, several studies have shown that there is a divergence between official and real-world values that it could be up to 40% in the NEDC. The introduction of the WLTP was expected to curb this divergence, but it is uncertain whether it can fully address the problem. In order to address this issue, future legislation aims at monitoring on-road fuel consumption and subsequently CO2 emissions by utilizing on-board fuel consumption meters. The current study investigates a monitoring approach that obtains and normalizes on-road vehicle operation data and estimate CO2 emissions through vehicle simulation. The first step is to create the vehicle’s engine fuel consumption map, based on laboratory vehicle measurements in order to use it as reference data. Subsequently, a methodology is developed to produce the vehicle’s engine map from signals retrieved through the OBD port in order to emulate data availability under a monitoring scheme. The methodology to derive the vehicle’s engine fuel consumption map includes an…
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Numerical Study of the Maximum Impact on Engine Efficiency When Insulating the Engine Exhaust Manifold and Ports During Steady and Transient Conditions

Universitat Politècnica de València-Alberto Broatch, Pablo Olmeda, Jaime Martin, Amin Dreif
  • Technical Paper
  • 2020-37-0002
To be published on 2020-06-23 by SAE International in United States
In the present work, a study about the impact on engine performance, fuel consumption and turbine inlet and outlet temperatures adding thermal insulation to the exhaust ports, manifold and pipes before the turbocharger of a 1.6L Diesel engine is presented. First, a 0D/1D model of the engine was developed and thoroughly validated by means of an extensive testing campaign. The validation was performed by means of steady state or transient running conditions and in two different room temperatures: 20ºC and -7ºC d. Once the validation was complete, in order to quantify the significance of adding thermal isolations, the simulations were performed setting the exhaust air path before the turbine as adiabatic. This is evaluated the maximum gain of the technology. Results showed that the thermal insulation proved to have a great potential in regard to T4 increase since this would reduce the warm up time of the aftertreatment systems. However, its impact on engine efficiency was limited in both steady and transient conditions.
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Study of Friction Reduction Potential in Light- Duty Diesel Engines by Lightweight Crankshaft Design Coupled with Low Viscosity Oil

General Motors-Salvatore Mafrici
  • Technical Paper
  • 2020-37-0006
To be published on 2020-06-23 by SAE International in United States
Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with more stringent homologation cycles and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystem has been one of the most important topics of modern Diesel engine development. The present paper analyzes the crankshaft potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of crankshaft design itself and oil viscosity characteristics (including new ultra-low-viscosity formulations already discussed in SAE Paper 2019-24-0056). For this purpose, a combination of theoretical and experimental tools have been used to design an extremely lightweight crankshaft and to evaluate the effects of main and conrod bearings dimensioning, clearances and oil viscosity, considering not only the impact from a friction perspective but also from a structural and…
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Effect of Prechamber on Exhaust Emission and Efficiency of a SI Small Engine Fuelled with Gaseous and Liquid Fuels

Istituto Motori CNR-Paolo Sementa
  • Technical Paper
  • 2020-37-0035
To be published on 2020-06-23 by SAE International in United States
The aim of the study was the optimization of the gasoline combustion process by means of a passive/active prechamber. The improvement of the engine efficiency in lean-burn operation condition is an opportunity to give further use of Spark Ignition (SI) engine. A commercial small Spark Ignition (SI) engine was modified with a proper designed prechamber fuelled with methane. Engine performance in terms of indicated Mean effective pressure, heat release rate and fuel Consumption were evaluated as well as gaseous emissions. Particulate Mass, Number and Size Distributions were measured. Several engine operative conditions were investigated at full load varying the engine speeds for stoichiometric and lean conditions and with different prechamber types. The results were compared with those obtained with the engine equipped with the standard spark plug. The results indicated that both performance and emissions were strongly influenced by the prechamber.
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Fuel Consumption and Emission Reduction for Hybrid Electric Vehicles with electrically heated Catalyst

TU Dresden-Frank Atzler
TU Muenchen-Georg Wachtmeister
  • Technical Paper
  • 2020-37-0017
To be published on 2020-06-23 by SAE International in United States
Hybridization is a promising way to further reduce the CO2 emissions of passenger vehicles. However, high engine efficiencies and the reduction of engine load, due to torque assist by an electric motor, cause a decrease of exhaust gas temperature levels. This leads to an increased time to light-off of the catalysts resulting in an overall lower efficiency of the exhaust aftertreatment system. Especially in low load driving conditions, at cold ambient temperatures and on short distance drives, the tailpipe pollutant emissions are severely impacted by these low efficiency levels. To ensure lowest emissions at all driving conditions, catalyst heating methods must be used. In conventional vehicles internal combustion engine measures, e.g. late combustion can be applied. A hybrid system with an electrically heated catalyst enables further methods such as the increase of engine load, the so-called load point shifting by the electric motor or using the energy from the battery for electric catalyst heating. Since these methods result either directly or indirectly in additional fuel consumption there is a conflict of objectives between a fast…
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Impact of Thermal Management of the Three-Way Catalyst on the Energy Efficiency of a P2 Gasoline FHEV

Università del Salento-Marco Benegiamo, Andrea Valletta, Antonio Carlucci
Università di Roma Tor Vergata-Vincenzo Mulone
  • Technical Paper
  • 2020-37-0019
To be published on 2020-06-23 by SAE International in United States
Gasoline Full Hybrid Electric Vehicles (FHEVs) are recognized as a cost-effective solution to comply with upcoming emissions legislation. However, several studies have highlighted that frequent start-and-stops worsen the HC tail-pipe emissions, especially when the light-off temperature of the three-way catalyst (TWC) has not been reached. In fact, strategies only addressing the minimization of fuel consumption tend to delay engine activation and hence TWC warming, especially during urban driving. Goal of the present research is therefore to develop an on-line powertrain management strategy accounting also for TWC temperature, in order to reduce the time needed to reach TWC light-off temperature. A catalyst model is incorporated into the model of the powertrain where torque-split is performed by an adaptive equivalent consumption minimization strategy (A-ECMS). The developed A-ECMS operates on a domain of power-split combinations between electric machine and internal combustion engine, which, aside from satisfying the torque demand, also ensure a controlled ICE torque derivative as well as a controlled ICE start-and-stop frequency. Hence, the algorithm which is extended for TWC thermal management, incorporates a penalty on…
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Simplified Cost-effective Aftertreatment System for Electrified Diesel Applications

Exothermia SA-Dimitrios Karamitros, Christos Avgerinos, Stavros Skarlis, Grigorios Koltsakis
GM Global Propulsion System-Giuseppe Previtero, Fransesco Bechis
  • Technical Paper
  • 2020-37-0023
To be published on 2020-06-23 by SAE International in United States
The Diesel powertrain remains an important CO2 reduction technology in specific market segments due to its inherent thermodynamic combustion efficiency advantages. Diesel powertrain hybridization can bring further potential for CO2 emissions reduction. However, the associated reduction in the exhaust gas temperature may negatively impact the performance of the exhaust aftertreatment (EAT) system and challenge the abatement of other emissions, especially NOx. Considering that active urea-SCR systems may be required to ensure compliance with the legislative limits, the total cost of the hybrid Diesel powertrain is expected to increase even more, therefore making it less commercially attractive. We present a model-based analysis of a 48V Diesel mild hybrid electric vehicle (MHEV) which is combined with an exhaust aftertreatment (EAT) system using Lean-NOx trap (LNT) technology. The overall de-NOx performance is further enhanced with the addition of passive SCR catalysts to benefit from the on-board ammonia formation during rich combustion events. Since the modeling framework is fully physico-chemically informed, it allows the investigation of various topologies, catalyst geometrical and chemical properties. Moreover, the model includes a simplified…
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Design of the Compression Chamber and Optimization of the Sealing of a Novel Rotary Internal Combustion Engine using CFD

Aristotle University of Thessaloniki-Savvas S. Savvakis, Elias Nassiopoulos, Dimitrios Mertzis, Zissis Samaras
  • Technical Paper
  • 2020-37-0007
To be published on 2020-06-23 by SAE International in United States
The increasing demand for lower fuel consumption and pollutant emissions favours the development of novel engine configurations. In line with this demand, the present contribution aims to investigate the sealing performance of a new concept rotary split-engine with a very promising thermal efficiency, a very low NOx emissions' level, and a much higher power density than any conventional internal combustion engine can. It uses the Atkinson cycle, a low-temperature combustion process and when it uses two pistons, symmetrically positioned around its shaft, it gives one power stroke every 180 degrees. The main focus of this work is to provide all the steps followed so far in order to ensure an efficient sealing and operation of the compression process of this engine, including the 1D & CFD simulations, CAD design & optimisation, and experimental campaign for verifying the digital results. The so-far investigation and experiments conclude that this new rotary engine can work with no oil lubrication inside the compression chamber and with much lower mechanical losses compared to the existing reciprocating engines.
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Assessing the Engine-Out Pollutant Emissions of a S.I. Engine for Hybrid Powertrain Applications

Université de Bourgogne Franche-Comté-Jérémy Pelluet, Alan Keromnes, Luis Le Moyne
Université de Lyon - IFSTTAR AME ECO7-Alice Guille des buttes, Bruno Jeanneret
  • Technical Paper
  • 2020-37-0016
To be published on 2020-06-23 by SAE International in United States
Car manufacturers are introducing more and more hybrid powertrains in order to reach CO2 emissions targets and answer increasingly stringent pollutant emission regulations such as unburned hydrocarbons (HC), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter. The addition of an electric engine to a thermal engine introduces an additional degree of freedom in the energy management of the powertrain since two energy sources are available. Thus, the energy management system must also account for regulated pollutant emissions when devising an optimal energy management strategy to avoid a pollutant emission increase due to CO2 only driven optimisation. It is therefore necessary to model the influence of thermal engine operating conditions such as load and speed on these emissions to evaluate their concentration in the exhaust gases. This study presents an empiric modelling approach based on an extensive parametric study using a spark-ignition port-injection four-cylinder engine. Such a model intend to be used in the context of hybrid powertrain optimization. In order to reduce the computing costs required by ECU (Engine Control Unit), the number of…
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Plug-in Electric Vehicles fueled with Green Fuels in LTC mode

Jesus Benajes
Universitat Politecnica de Valencia-Antonio Garcia, Javier Monsalve-Serrano, Santiago Martinez
  • Technical Paper
  • 2020-37-0026
To be published on 2020-06-23 by SAE International in United States
Plug-in Hybrid Electric Vehicles (PHEVs) can be considered as the most promising technology to achieve the European CO2 targets in 2025 together with a moderate infrastructure modification. However, the real benefits, in terms of CO2 emissions, depend on a great extent on the energy source (fuel and electricity mix), user usage, and vehicle design. Moreover, the electrification of the powertrain does not reduce other emissions as NOx and particles (mainly soot). In the last years, low temperature combustion (LTC) modes as the reactivity-controlled compression ignition (RCCI) have shown to achieve ultra-low NOx and soot emission simultaneously due to the use of two fuels with different reactivity and high exhaust gas recirculation (EGR) rates. Therefore, the aim of this work is to assess, through numerical simulations fed with experimental results, the effects of different energy sources on the PHEV performance and emissions. The dual-fuel ICE was fueled with diesel as high reactivity fuel and two different low reactivity fuel: gasoline and ethanol. The powertrains are optimized to meet the European homologation legislation (WLTP) for PHEVs. The…