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A Comprehensive Study on BSVI Turbocharger Selection and its Deterioration with Closed Crank-Case Ventilation in Heavy Commercial Vehicles

Automobile Industry-Juzer Jaliwala
Automotive-Aravind Mohan
  • Technical Paper
  • 2019-24-0061
To be published on 2019-08-15 by SAE International in United States
BSVI Norms getting implemented in India by April 2020 and every heavy commercial vehicle OEMs viewing it as one of the greatest challenge, there are many factors and trade off that should be considered at every step of the project. The newly developed engine in BSVI will be equipped with actuators like Intake Throttle Valve, Exhaust Throttle Valve and combination of these flap operations with turbocharger output plays a prominent role in controlling performance and emission. Turbocharger selection plays major role in engine and vehicle performance on road and testcell. Turbo charger plays an apex role in providing both required boost to the engine performance and set up a control on emissions. This study focusses on the use of different AVU (Air Valve Unit) controlled waste gate turbochargers from different suppliers and how it’s getting matched with the engine performance requirements. The fluctuations observed in boost pressure at higher loads due to the waste gate operational inconsistency and its solution is also explained. The legislation stresses on importance of positive crank case ventilation (connected to…

Development and validation of SI combustion models for natural-gas heavy-duty engines

Politecnico di Milano-Lorenzo Sforza, Tommaso Lucchini, Giovanni Gianetti, Gianluca D'Errico
  • Technical Paper
  • 2019-24-0096
To be published on 2019-08-15 by SAE International in United States
Flexible, reliable and consistent combustion models are necessary for the improvement of the next generation spark-ignition engines. Different approaches have been proposed and widely applied in the past. However, the complexity of the process involving ignition, laminar flame propagation and transition to turbulent combustion need further investigations. Purpose of this paper is to compare two different approaches describing turbulent flame propagation. The first approach is the one-equation flame wrinkling model by Weller, while the second is the Coherent Flamelet Model (CFM). Ignition is described by a simplified deposition model while the correlation from Herweg and Maly is used for the transition from the laminar to turbulent flame propagation. Validation of the proposed models was performed with experimental data of a natural-gas, heavy duty engine running at different operating conditions. To deeply analyze main differences between Weller and CFM models, a detailed comparison of computed and experimental data was performed in terms of cylinder pressure, heat release rate, wall heat transfer, distribution of progress variable and flame surface density.

Possibilities of wall heat transfer measurements at a supercharged Euro IV heavy-duty Diesel engine with high EGR-rates, an in-cylinder peak pressure of 250 bar and injection pressure up to 2500 bar

Daimler AG-Christian HENNES, Jürgen Lehmann
KIT Karlsruhe Institute Of Technology-Thomas Koch
  • Technical Paper
  • 2019-24-0171
To be published on 2019-08-15 by SAE International in United States
A raise of efficiency is, especially for CV, the strongest selling point concerning the TCO. Accompanied by legislations, with contradictive development demands, satisfying solutions have to be found. The analysis of energy losses in modern engines shows three influencing parameters. The losses resulting from taking real gas properties and non-ideal combustion into account have only a limited potential for gains, wall heat losses are currently believed to have the highest optimization potential. Critical for the occurrence of these losses is the wall heat transfer, which can be described by coefficients. To reduce WHT accompanying losses a decrease of energy transfer between combustion gas and combustion chamber wall is necessary. A measurement of heat fluxes is needed to determine the WHT relations at the combustion chamber of an engine. Methods to reduce the WHT can be developed and their effectiveness can be evaluated. As this is not done before for a heavy-duty engine, with peak pressures up to 250 bar, an increased in-cylinder turbulence and high EGR-rates is presented the following. The different methods to determine…

Optimization of the Exhaust Aftertreatment System of a Heavy Duty Engine by means of Variable Valve Timing

Technische Universität Braunschweig-Marius Betz, Peter Eilts
  • Technical Paper
  • 2019-24-0143
To be published on 2019-08-15 by SAE International in United States
In view of the current political debate, it can be assumed that the nitrogen oxide limits for commercial vehicles will be further reduced. This is also demonstrated by the currently voluntary certification of the CARB Optional Low NOX legislation, which requires nitrogen oxide emissions of 0.027 g / kWh. This corresponds to a reduction of 93% compared to the current EU VI standard. Therefore, the optimization of EAT systems represents an essential research focus for future commercial vehicle applications. One way to optimize the EAT system may be the usage of variable valve actuation. Existing investigations show an exhaust gas temperature increase with Miller timing, but the authors conclude that it cannot accelerate the heating process. With regard to the effects on the exhaust aftertreatment system and the resulting tailpipe emissions, only improved HC and CO oxidation could be identified so far. In addition, a potential for improved NOX reduction is expected in the exhaust gas temperature increase. Therefore, investigations are carried out at the Institute of Internal Combustion Engines of the Technical University of…

Design and Development of a new piston for an off-road Diesel engine with special focus on improvements of the piston cooling jet. Part II: design improvements and final validation.

Duraldur-Michele Rossi
Kohler Engines-Filippo Monzani, Davide Bottazzi
  • Technical Paper
  • 2019-24-0041
To be published on 2019-08-15 by SAE International in United States
This paper is the conclusion of a joint experimental/simulation effort to improve the effectiveness of piston cooling for a new generation engine for off-road applications. Motivations for the activity were described in the preceding part I of the paper. This part II describes a design improvement process aimed at increasing the effectiveness of piston cooling In particular, steady-state CFD simulations of several piston cooling jet solutions are initially carried out to select the most promising variants, which are then prototyped using 3D printing. Prototypes are tested using a specific hydraulic bench to compare and to validate the CFD analyses. Three design variants are then selected and analysed using a more complex CFD approach involving fully transient Volume of Fluid simulations of the piston gallery. In particular, the piston gallery is modelled imposing actual time-dependent oil inflow conditions together with the instantaneous acceleration resulting from the combination of the piston motion law and the gravity. A complete validation process is finally set up to check the effectiveness of the proposed solution: piston thermal field measurements using…

Design and development of a new piston for an off-road Diesel engine with special focus on improvements of the piston cooling jet. Part I: root cause analysis of initial design failure.

Duraldur-Michele Rossi
Kohler Engines-Filippo Monzani, Davide Bottazzi, Riccardo Fornaciari lng
  • Technical Paper
  • 2019-24-0043
To be published on 2019-08-15 by SAE International in United States
Similarly to passenger car engine manufacturers, it is increasingly common for off-road engine manufactures to extend the array of their products increasing the engine BMEP or, in other words, downsizing the engine. This strategy leads to increase the thermos-mechanical stress of the engine components, which therefore need often to be re-designed. Pistons, in particular, are among the most critical components, because high local temperatures strongly reduce their mechanical properties. Therefore, relevant design efforts to ensure increased piston cooling are demanded. This paper, based on a real case occurred during the early development stage of a new Diesel unit, focuses on the criticalities of piston cooling design. A preliminary piston design, based on Finite Element Analyses and Thermal Analyses, was initially prototyped and validated under both performance and durability tests; the validation, nevertheless, evidenced a design criticality as a thermal crack occurred during the endurance tests. An in-depth analysis to motivate the failure was therefore carried out by means of dedicated experimental tests, which allowed to identify the root cause and to highlight the criticalities of…

Large eddy simulation of an ignition wave front in a heavy duty partially premixed combustion engine

Lund Univ.-Christian Ibron
Lund University-Hesameddin Fatehi, Mehdi Jangi, Xue-Song Bai
  • Technical Paper
  • 2019-24-0010
To be published on 2019-08-15 by SAE International in United States
In partially premixed combustion engines high octane number fuels are injected into the cylinder during the late part of the compression cycle, giving the fuel and oxidizer enough time to mix into a desirable stratified mixture. If ignited by auto-ignition such a gas composition can react in an ignition wave-front dominated combustion mode. 3D-CFD modeling of such a combustion mode is challenging as the reaction speed is dependent on both mixing history and turbulence acting on the reaction wave. This paper presents a large eddy simulation (LES) study of the effects of energetic turbulence scale on the fuel/air mixing and on the propagation of reaction wave. The results are compared with optical experiments to validate both pressure trace and ignition location. The studied case is a closed cycle simulation of a single cylinder of a Scania D13 engine running PRF81 (81% iso-octane and 19% n-heptane). One-equation-eddy transported SGS-turbulence closure is used in the LES; the fuel spray is modelled using an Lagrangian particle tracking (LPT) approach. The coupling of flow and chemical reactions is done…

CFD Investigation of the Effects of Gas’ Methane Number on the Performance of a Heavy-Duty Natural-Gas Spark-Ignition Engine

Universita degli Studi di Perugia-Luca Ambrogi, Michele Battistoni, Lorenzo Gasbarro
West Virginia Univ-Jinlong Liu
  • Technical Paper
  • 2019-24-0008
To be published on 2019-08-15 by SAE International in United States
Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of year, and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to spark ignition operations simulated engine operation under lean-combustion, low-speed, and medium load conditions. To eliminate the effect of different gas energy density, three NG blends of similar lower heating value but different H/C ratio have been investigated at fixed spark timing. The results indicated that a lower H/C ratio increased flame propagation and thus increased in-cylinder pressure and indicated mean effective pressure. In addition, the lower H/C ratio increased thermal efficiency despite the higher heat transfer, most probably due to the more advanced combustion phasing. Also, a higher H/C ratio reduced…

Experimental Investigation of Combustion Characteristics in a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural-Gas Spark-Ignition Operation

West Virginia Univ-Jinlong Liu
West Virginia Univ.-Cosmin Dumitrescu
  • Technical Paper
  • 2019-24-0124
To be published on 2019-08-15 by SAE International in United States
The conversion of existing diesel engines to natural gas operation can reduce U.S. dependence on petroleum imports and curtail engine-out emissions. Diesel compression ignition engines can be modified to NG spark ignition, by replacing the diesel injector with a NG spark plug and by fumigating NG in the intake manifold, to increase utilization of natural gas heavy-duty transportation sector. As the original diesel piston is maintained during conversion to decrease engine modification cost, the major of this study was to investigate the lean-burn characteristic of natural gas burning in this bowl-in-piston combustion chamber, which can accelerate the introduction of heavy-duty natural gas vehicles. Data analysis from engine experiments that changed spark timing indicated a two-stage combustion process in such retrofitted engines, which is different from traditional spark ignition engines. Inside-bowl burning is one combustion stage which experienced fast flame propagation and burned majority of fuel mass. An important mass trapped in the squish region but burned more slowly formed the other combustion stage. This combustion feature contributed to an almost identical end of combustion in…

Comparison of different particulate measurement techniques at a heavy duty diesel engine test bed

KIT Karlsruhe Institute of Technology-Tobias Michler, Johannes Dörnhöfer, Daniel Erforth, Alexander Heinz, Kai Scheiber, Philipp Weber, Niclas Nowak, Heiko Kubach, Jörg Meyer PhD, Thomas Koch, Achim Dittler
  • Technical Paper
  • 2019-24-0158
To be published on 2019-08-15 by SAE International in United States
In addition to particle number and mass, knowledge about particulate size distribution (PSD) in the exhaust gas of combustion engines increases in importance due to a significant correlation between particle size and effectiveness of particulate filters and the respirability of soot. There are different ways and measurement devices available for the measurement of soot and its properties. Especially for small particle diameters (D<1µm), the PSD is usually characterized by the electrical mobility of the sampled particles. These measurements are subjected to uncertainty mainly due to air dilution of the sampled gas, installation of the probe, temperatures as well as the measurement principle and device itself. In order to determine the measurement uncertainty, two different spectrometers, a TSI EEPS 3090 and a Cambustion DMS 500 were installed and operated simultaneously at a single-cylinder heavy duty diesel engine at the Institute of Combustion Engines of the Karlsruhe Institute of Technology (KIT). For additional comparison, an AVL Smokemeter was used. Variations of the position and geometry of the probe system were performed, regarding a potential influence on the…