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Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Magneti Marelli SpA - Powertrain-Federico Stola, Matteo De Cesare
University of Bologna-Vittorio Ravaglioli, Giacomo Silvagni, Fabrizio Ponti
  • Technical Paper
  • 2019-24-0112
To be published on 2019-09-09 by SAE International in United States
Nowadays, compression-ignited engines are considered the most efficient and reliable technology for automotive applications. However, mainly due to the current emission regulations, that require increasingly stringent reductions of NOx and particulate matter, the use of diesel-like fuels is becoming a critical issue. For this reason, a large amount of research and experimentation is being carried out to investigate innovative combustion techniques suitable to simultaneously mitigate the production of NOx and soot, while improving engine efficiency. In this scenario, the combined use of compression-ignited engines and gasoline-like fuels proved to be very promising, especially in case the fuel is directly-injected in the combustion chamber at high pressure. The presented study analyzes the combustion process produced by the direct injection of gasoline in a compression-ignited light-duty engine. The engine under investigation has been modified to guarantee a stable engine operation over its whole operating range, that is achieved controlling boost pressure and temperature together with the design of the multiple injections pattern. The analysis of the experimental tests highlights the impact of several control variables on combustion…
 

Axial Flow Turbine Concept for Conventional and E-Turbocharging

Brunel University-Apostolos Pesyridis
Universita di Napoli Federico II-Alessandro Cappiello, Raffaele Tuccillo, Maria Cristina Cameretti
  • Technical Paper
  • 2019-24-0185
To be published on 2019-09-09 by SAE International in United States
Engine downsizing has established itself as one of the most successful strategies to reduce fuel consumption and pollutant emissions in the automotive field. In this regard, a major role is played by the turbocharging, allowing to increase engine power density, and so reducing engine size and weight. However, the need for turbocharging imposes some issues to be solved. In the attempt of mitigating turbo lag and poor low-end torque, many solutions have been presented in the open literature so far, such as: low inertia turbine wheels and variable geometry turbines; or even more complex concepts such as twin turbo and electrically assisted turbochargers. None of them appears as definitive, though. As possible way of reducing turbine rotor inertia, and so the turbo lag, also the change of turbine layout has been investigated, and it revealed itself as viable option, leading to the use of mixed-flow turbines. Only recently, the use of axial-flow turbines, with the aim of reducing rotor inertia, has been proposed as well. The current paper documents a case study involving the design…
 

A Comprehensive Study on Euro 6 Turbocharger Selections and Its Deterioration with Closed Crank-Case Ventilation in Heavy Commercial Vehicles

VE Commercial Vehicles Ltd-Aravind Mohan, Juzer Jaliwala, Kunaal Bhagat, Kumar Patchappalam
  • Technical Paper
  • 2019-24-0061
To be published on 2019-09-09 by SAE International in United States
Euro 6 emission norms are getting implemented in India from April 2020 and it is being viewed as one of the greatest challenges ever faced by the Indian automotive industry. In order to achieve such stringent emission norms a good strategy will be to optimize the engine out emission through in cylinder emission control techniques and a right sized after treatment system has to be used for this optimized engine. There exist several factors and trade-off between these should be established for in cylinder optimization of emissions. Since the turbocharger plays an apex role in controlling both the performance and engine out emissions of a CI engine, turbocharger selection is a crucial step in the development of new generation of Euro 6 engines in India. Such engines are equipped with additional actuators such as Intake Throttle Valve and Exhaust Throttle Valve and combination of these flap operations with turbocharger output plays a prominent role in controlling performance and emission. This study focusses on the use of different AVU (Air Valve Unit) controlled waste gate turbochargers…
 

Glossary of Engine Cooling System Terms

Cooling Systems Standards Committee
  • Ground Vehicle Standard
  • J1004_201904
  • Current
Published 2019-04-22 by SAE International in United States
The objective of this glossary is to establish uniform definitions of parts and terminology for engine cooling systems. Components included are all those through which engine coolant is circulated: water pump, engine oil cooler, transmission and other coolant-oil coolers, charge air coolers, core engine, thermostat, radiator, external coolant tanks, and lines connecting them.
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Optimization of a Diesel Engine with Variable Exhaust Valve Phasing for Fast SCR System Warm-Up

University of Michigan-Pavan Kumar Srinivas, Rasoul Salehi
Published 2019-04-02 by SAE International in United States
Early exhaust valve opening (eEVO) increases the exhaust gas temperature by faster termination of the power stroke and is considered as a potential warm up strategy for diesel engines aftertreatment thermal management. In this study, first, it is shown that when eEVO is applied, the engine main variables such as the boost pressure, exhaust gas recirculation (EGR) and injection (timing and quantity) must be re-calibrated to develop the required torque, avoid exceeding the exhaust temperature limits and keep the air fuel ratio sufficiently high. Then, a two-step procedure is presented to optimize the engine operation after the eEVO system is introduced, using a validated diesel engine model. In the first step, the engine variables are optimized at a constant eEVO shift. In the second step, optimal eEVO trajectories are calculated using Dynamic Programming (DP) for a transient test cycle. The optimized results indicate that with early EVO, the boost pressure should be increased to provide enough cylinder air charge and to maintain the engine torque. External EGR can be reduced due to increased internal EGR…
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Effect of Diamond-Like Carbon Coating on Anti-Scuffing Characteristics of Piston Pins

Hino Motors, Ltd.-Shoichiro Usui, Hideki Kato, Hiroshi Nakajima, Kiyohiro Shimokawa
Published 2019-04-02 by SAE International in United States
It has been proposed that downspeeding combined with high boost levels would effectively reduce fuel consumption in heavy-duty diesel engines. Under low-speed and high-boost operating conditions, however, the in-cylinder gas pressure, which acts on the piston crown, is greater than the piston inertia force (such that there is no force reversal), over the entire range of crank angles. Therefore, the piston pin never lifts away from the main loading area (the bottom) of the connecting rod small-end bushing where the contact pressure against the piston pin is highest. In such operating conditions, lubricant starvation is easily induced at the interface between the piston pin and small-end bushing. Through carefully devised engine tests, the authors confirmed that the piston pin scuffing phenomenon arises when the boost pressure exceeds a critical value at which the no-force reversal condition appears. Furthermore, to prevent this piston pin scuffing when there is no force reversal, the authors applied a type of diamond-like carbon (DLC), a hydrogenated tetrahedral amorphous carbon (ta-C:H) coating, to the piston pins and then evaluated its anti-scuffing…
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Steady-State, Transient and WLTC Drive-Cycle Experimental Performance Comparison between Single-Scroll and Twin-Scroll Turbocharger Turbine

Imperial College London-Ricardo Martinez-Botas
Mitsubishi Heavy Industries Engine & Turbochargers-Motoki Ebisu
Published 2019-04-02 by SAE International in United States
The use of twin-scroll turbocharger turbine in automotive powertrain has been known for providing better transient performance over conventional single-scroll turbine. This has been accredited to the preservation of exhaust flow energy in the twin-scroll volute. In the current study, the performance comparison between a single and twin-scroll turbine has been made experimentally on a 1.5L passenger car gasoline engine. The uniqueness of the current study is that nearly identical engine hardware has been used for both the single and twin-scroll turbine volutes. This includes the intake and exhaust manifold geometry, turbocharger compressor, turbine rotor and volute scroll A/R variation trend over circumferential location. On top of that, the steady-state engine performance with both the volutes, has also been tuned to have matching brake torque. Such highly comparable setup enabled a more precise evaluation on the effect of pulse-isolation in the twin-scroll turbine volute during transient process. The steady-state performance comparison shows the amplitude of exhaust pulse in the twin-scroll volute is substantially higher than in the single-scroll volute, hence confirming the preservation of pulse…
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System Level 1-D Analysis of an Air-System for a Heavy-Duty Gasoline Compression Ignition Engine

Aramco Research Center-Praveen Kumar, Yuanjiang Pei, Michael Traver
BorgWarner Turbo Systems-John Watson
Published 2019-04-02 by SAE International in United States
A detailed study of various air system configurations has been conducted for a prototype gasoline compression ignition (GCI) engine using a Cummins MY2013 ISX15 heavy-duty diesel engine as the base platform. The study evaluated the configurations with the assumption that RON80 gasoline would be used as the fuel and the combustion chamber would have a geometric compression ratio (CR) of 16.5.Using 3-D computational fluid dynamics (CFD) simulations, a high efficiency & low engine-out NOx GCI combustion recipe was developed across the five engine operating points from the heavy-duty Supplemental Emissions Test (SET) cycle: A100, B25, B50, B75, and C100. The CFD generated air-thermal boundary conditions and the combustion burn-rate & injector rate-of-injection profiles were imported into a calibrated 1-D engine model for the air-handling systems analysis. For the RON80 GCI concept, an engine-out NOx range 1-1.5 g/kWh was targeted and this drove a need for higher boost pressure and EGR rates with intake temperatures in the 65°C-70°C range. The production air system comprising a single stage turbocharger and a high-pressure exhaust gas recirculation (HPEGR) system…
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Preliminary Testing of n-Butanol HCCI on High Compression Ratio Diesel Engines

Shanghai Jiao Tong University-Tie Li
University of Windsor-Simon Leblanc, Prasad Divekar, Xiaoye Han, Jimi Tjong, Ming Zheng
Published 2019-04-02 by SAE International in United States
The control of combustion phasing in homogeneous charge compression ignition (HCCI) combustion is investigated with neat n-butanol in this work. HCCI is a commonly researched combustion mode, owing to its improved thermal efficiency over conventional gasoline combustion, as well as its lower nitrogen oxide (NOx) and particulate matter emissions compared to those of diesel combustion. Despite these advantages, HCCI lacks successful widespread implementation with conventional fuels, primarily due to the lack of effective combustion phasing control. In this preliminary study, chemical kinetic simulations are conducted to study the auto-ignition characteristics of n-butanol under varied background pressures, temperatures, and dilution levels using established mechanisms in CHEMKIN software. Increasing the pressure or temperature lead to a shorter ignition delay, whereas increasing the dilution by the application of exhaust gas recirculation (EGR) leads to a longer ignition delay. These ignition delay simulation results are used as a guide for the experimental study of n-butanol HCCI combustion on engine tests. Experiments are conducted near engine mid-load (~7 bar IMEP) on two engines with high compression ratios (i.e. 16.2:1 and…
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A Physics-Based, Control-Oriented Turbocharger Compressor Model for the Prediction of Pressure Ratio at the Limit of Stable Operations

Ohio State University-Alexandra Taylor, Marcello Canova
Universita Degli Studi Di Genova-Anna Misley
Published 2019-04-02 by SAE International in United States
Downsizing and boosting is currently the principal solution to reduce fuel consumption in automotive engines without penalizing the power output. A key challenge for controlling the boost pressure during highly transient operations lies in avoiding to operate the turbocharger compressor in its instability region, also known as surge. While this phenomenon is well known by control engineers, it is still difficult to accurately predict during transient operations. For this reason, the scientific community has directed considerable efforts to understand the phenomena leading to the onset of unstable behavior, principally through experimental investigations or high-fidelity CFD simulations. On the other hand, less emphasis has been placed on creating control-oriented models that adopt a physics-based (rather than data-driven) approach to predict the onset of instability phenomena.This work describes a centrifugal compressor model that focuses on predicting the behavior at operating conditions close to the stability limit. The objective of the model is to facilitate the development of estimation and control algorithms to optimize the boost pressure in a wider set of operating conditions. The model captures some…
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