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Environmental Analysis Based on Life Cycle Assessment: An Empirical Investigation on the Conventional and Hybrid Powertrain

University of Naples, Parthenope-Antonio Forcina
University of Rome, Niccolò Cusano-Luca Silvestri, Gabriella Arcese
Published 2019-10-07 by SAE International in United States
The Life Cycle Sustainability Assessment (LCA) methodology is today considered as a crucial paradigm with multiple levels of analysis, including the economic, social and environmental aspects. In this scenario, the purpose of the present research is to carry out an accurate and extensive LCA based analysis to compare the environmental impact, between conventional gasoline and hybrid vehicle powertrains. Two different powertrain scenarios were considered maintaining the same vehicle chassis. The performed analysis concerned resources and energy consumption as well as pollutant emission of each process, evaluating the impact of powertrain production, the vehicle use phase, and powertrain end of life scenarios. A large set of indicators - including human toxicity, eutrophication, and acidification - was considered. The study indicates that the potential of electrified vehicles basically depends on efficient production and recycling of the battery. We found that the conventional powertrain determines a higher Global Warming Potential (GWP) than hybrid powertrain (by almost 30%). Conversely, the water-related impact is higher in hybrid powertrain, and this is associated to the extraction and processing of the metal…
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Effects of Turbulence Modeling and Grid Quality on the Zonal URANS/LES Simulation of Static and Reciprocating Engine-Like Geometries

SAE International Journal of Engines

University of Rome Tor Vergata-Luca Silvestri, Gino Bella
University of Tuscia-Vesselin Krassimirov Krastev
  • Journal Article
  • 2018-01-0173
Published 2018-04-03 by SAE International in United States
The interest in Unsteady Reynolds-Averaged Navier-Stokes (URANS)/Large Eddy Simulation (LES) hybrids, for the simulation of turbulent flows in Internal Combustion Engines (ICE), is consistently growing. An increasing number of applications can be found in the specialized literature for the past few years, including both seamless and zonal hybrid formulations. Following this trend, we have already developed a Detached Eddy Simulation (DES)-based zonal modeling technique, which was found to have adequate scale-resolving capabilities in several engine-like reference tests. In the present article we further extend our study by evaluating the effects of the underlying turbulence model and of the grid quality/morphology on the scale-resolved part of the flow. For that purpose, we consider DES formulations based on an enhanced version of the k-g URANS model and on the URANS form of the popular RNG k-ε model. The simulated test cases include a static intake valve geometry and a reference reciprocating piston/cylinder assembly. All the numerical predictions are assessed against the available experimental datasets and with previous computational studies made by other research groups.
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A Zonal-LES Study of Steady and Reciprocating Engine-Like Flows Using a Modified Two-Equation DES Turbulence Model

University of Rome "Tor Vergata"-Luca Silvestri, Giacomo Falcucci, Gino Bella
University of Tuscia-Vesselin Krassimirov Krastev
Published 2017-09-04 by SAE International in United States
A two-equation Zonal-DES (ZDES) approach has been recently proposed by the authors as a suitable hybrid URANS/LES turbulence modeling alternative for Internal Combustion Engine flows. This approach is conceptually simple, as it is all based on a single URANS-like framework and the user is only required to explicitly mark which parts of the domain will be simulated in URANS, DES or LES mode. The ZDES rationale was initially developed for external aerodynamics applications, where the flow is statistically steady and the transition between zones of different types usually happens in the URANS-to-DES or URANS-to-LES direction. The same “one-way” transition process has been found to be fairly efficient also in steady-state internal flows with engine-like characteristics, such as abrupt expansions or intake ports with fixed valve position. However, assuming that a pure LES treatment is applied on the in-cylinder region, the reciprocating nature of a real engine flow implies a “two-way” URANS-LES-URANS transition during the engine cycle. In the present work, we further validate the Zonal-LES mode (i. e. with only pure URANS and pure LES…
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