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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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The Virtual Engine Development for Enhancing the Compression Ratio of DISI-Engines by Means of Water Injection and Variable Valve Timing

FKFS-Antonino Vacca, Francesco Cupo, Marco Chiodi, Michael Bargende
Ford Werke GmbH-Oliver Berkemeier, Maziar Khosravi
  • Technical Paper
  • 2020-37-0010
To be published on 2020-06-23 by SAE International in United States
With the aim of significantly reducing emissions, while keeping CO2 production under control, gasoline engines are faced with a new challenge to survive the constraints imposed by the RDE cycles. Current downsized engines are developed with the most recent techniques for increasing efficiency, such as high direct injection pressure, selective valve actuation, variable turbine geometry, and innovative thermal management system. The factor limiting their further step towards enhanced efficiency is the onset of abnormal combustion process. Therefore the challenge for the further boost of modern engine efficiency is the improvement of the combustion process. Different combustion technics such as HCCI and the employment of pre-chamber have been investigated, but the possibility of effectively use them in a wide range of the engine map, by fulfilling at the same time the needing of fast load control are still limiting their dissemination. For these reasons the technologies for improving the characteristics of a standard combustion process are still deeply investigated. Among these water injection in combination with either early or late intake valve closing offers the possibility…
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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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Downsized-Boosted Gasoline Engine with Exhaust Compound and Dilute Advanced Combustion

General Motors LLC-Jeremie Dernotte, Paul M. Najt, Russell P. Durrett
  • Technical Paper
  • 2020-01-0795
To be published on 2020-04-14 by SAE International in United States
This article presents experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5: 1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expanded.The main goal of this work is to implement in this engine, advanced lean/dilute low-temperature combustion for low-NOx and high efficiency operation, and to address the transition between the different operating modes. Those include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion at higher loads, before transitioning to boosted homogenous and stochiometric spark-ignited combustion. Here, the mixed-mode combustion strategy is composed of a deflagration of a stratified mixture created by a late direct injection, then triggering a controlled autoignition of the surrounding gas, improving the robustness…
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Impact of fuel octane quality on various advanced vehicle technologies

Shell Global Solutions (Deutschland)-Caroline Magdalene Zinser, Patrick Haenel
Shell Global Solutions (UK)-Alastair Smith
  • Technical Paper
  • 2020-01-0619
To be published on 2020-04-14 by SAE International in United States
Fuel with higher octane content is playing a key role in optimising engine performance by allowing a more optimal spark timing which leads to increased engine efficiency and lower CO2 emissions. In a previous study the impact of octane was investigated with a vehicle fleet of 20 vehicles using market representative fuels, varying from RON 91 to 100. The resulting data showed a clear performance and acceleration benefit when higher RON fuel was used. In this follow-up study 10 more vehicles were added to the database. The vehicle fleet was extended to be more representative of Asian markets, thus broadening the geographical relevance of the database, as well as adding vehicles with newer technologies such as boosted down-sized direct injection engines, or higher compression ratio engines. Eight different fuel combinations varying in RON were tested, representing standard gasoline and premium gasoline in different markets around the world. The new results augment our previously published octane study and result in a vehicle fleet dataset comprising 30 cars from 18 different automotive manufactures. Two key metrics were…
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A path towards high efficiency SI combustion in a CFR engine: Cooling the intake to sub-zero temperatures

King Abdullah University of Science & Technology-Sufyan M. Jan, Abdulrahman Mohammed, Ali Elkhazraji, Jean-Baptiste Masurier
University of California-Robert Dibble
  • Technical Paper
  • 2020-01-0550
To be published on 2020-04-14 by SAE International in United States
Textbook engine thermodynamics predicts that SI (Spark Ignition) engine efficiency η is a function of both the compression ratio CR of the engine and the specific heat ratio γ of the working fluid. In practice the compression ratio of the SI engine is often limited due to “knock”. When this knock limit is reached, increase in heat transfer losses result in reduction in efficiency. One way to lower the end-gas temperature is to cool the intake gas before inducting it into the combustion chamber. With colder intake gases, higher CR can be deployed, resulting in higher efficiencies. In this regard, we investigated the indicated efficiency of the standard Waukesha CFR engine. The engine is operated in the SI engine mode. The engine was operated with three different mediums using the same fuel Methane (Gas). First is Air + Methane at room temperature, second was O2 + Argon + Methane gas mixture at room temperature, and lastly O2 + Argon +Methane at sub-zero conditions. We replace the Air by an Oxygen-Argon mixture to increase the specific…
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A Competitive Approach to an Active Exhaust Heat Recovery System Solution

Tenneco Inc.-Adam Kotrba, Timothy Gardner, John Stanavich, Raphael Bellard, Brian Kunkel, Nicholas Morley
  • Technical Paper
  • 2020-01-0161
To be published on 2020-04-14 by SAE International in United States
As greenhouse gas regulations continue to tighten, more opportunities to improve engine efficiency emerge, including exhaust gas heat recovery. Upon cold starts, engine exhaust gases downstream of the catalysts are redirected with a bypass valve into a heat exchanger, transferring its heat to the coolant to accelerate engine warm-up. This has several advantages, including reduced fuel consumption, as the engine’s efficiency improves with temperature. Furthermore, this accelerates readiness to defrost the windshield, improving both safety as well as comfort, with greater benefits in colder climates, particularly when combined with hybridization’s need for engine on-time solely for cabin heating. Such products have been in the market now for several years; however they are bulky, heavy and expensive, yielding opportunities for competitive alternatives. Customer voice expresses needs for less complex designs that reduce package space, mass and part count (i.e. cost) while maintaining or improving performance, including the integration of an active bypass control valve. This paper highlights the design of an exhaust heat recovery system including relative benchmarking of commercially available products, comparing various aspects of…
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Neat Oxymethylene Ethers: Combustion Performance and Emissions of OME2, OME3, OME4 and OME5 in a Single-Cylinder Diesel Engine

Technical University of Munich-Patrick Dworschak, Vinicius Berger, Martin Härtl, Georg Wachtmeister
  • Technical Paper
  • 2020-01-0805
To be published on 2020-04-14 by SAE International in United States
Diesel engines are arguably the superior device in the ground transportation sector in terms of efficiency and reliability, but suffer from inferior emission performance due to the diffusive nature of diesel combustion. Great research efforts gradually reduced nitrogen oxide (NOX) and particulate matter (PM) emissions, but the PM-NOX trade-off remained to be a problem of major concern and was believed to be inevitable for a long time. In the process of engine development, the modification of fuel properties has lately gained great attention. In particular, the oxygenate fuel oxymethylene ether (OME) has proven potential to not only drastically reduce emissions, but possibly resolve the formerly inevitable trade-off completely. Although intensified investigations with OME were conducted within the past decade, little is known about the specific influence of fuel properties inherent to unimolecular, high chain length OME on combustion characteristics, emission performance and particle size. The latter is of special concern, as studies on oxygenate fuels reported increased formation of nanoparticles, which are known to have adverse effects on human health. In this paper, the authors…