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Increase of Compressor Performance through the Use of Microstructures

Bionic Surface Technologies GmbH-Mikel Garcia de Albeniz, Peter Adrian Leitl
RINA-Emiliano Costa, Stefano Barberis
Published 2019-10-07 by SAE International in United States
Turbomachinery efficiency is becoming more and more relevant in order to reduce fuel consumption and mechanical wear of machines at the purpose of increasing their environmental sustainability and reliability. Optimized material identification and design is therefore of paramount importance. This paper describes how turbomachines can be optimized thanks to the effect of microstructures suitably created over the shapes of their constituting components in order to increase the overall efficiency via a simple coating solution. These structures, called riblets, consist of tiny streamwise grooved surfaces which are such to reduce drag in the turbulent boundary layer. Theoretical, numerical and experimental experiences gave a first estimation of the impact of riblets in industrial compressors. In this case, the riblet structures reduce the aerodynamic shear stress losses. The areas of higher interest are the diffuser and the volute, where the higher losses happen. The optimal size, position and effect on performance were analysed via simulation. The use of such an effective numerical means may give a precise evaluation about benefits in terms of efficiency increase as well as…
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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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Performance Evaluation of an Electric Vehicle with Multiple Electric Machines for Increased Overall Drive Train Efficiency

University of Ljubljana-Mario Vukotić, Damijan Miljavec
University of Rome Niccolò Cusano and S.C.I.R.E. Consortium-Laura Tribioli, Daniele Chiappini
Published 2019-10-07 by SAE International in United States
Proposed solutions for electric vehicles range from the simple single-motor drive coupled to one axle through a mechanical differential, to more complex solutions, such as four in-wheel motors, which ask for electronic torque vectoring. Main reasons for having more than one electric machine are: reduction of the rated power of each motor, which most likely leads to simplification and cost reduction of all the electric drive components; increased reliability of the overall traction system, enhancing fault tolerance ability; increase of the degrees of freedom which allows for control strategy optimization and efficiency improvement. In particular, electrical machines efficiency generally peaks at around 75% of load and this usually leads to machine downsizing to avoid operation in low efficiency regions. The same output performance can be achieved by using two or more electrical machines, rather than only one, of smaller size and running them at unequal load - one of the machines at higher load and the other(s) at lower load.In this paper, the performance of an electric vehicle with multiple electric machines is analyzed to…
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An ADAS Feature Rating System: Proposing a New Industry Standard

Velodyne LiDAR-David Heeren, Mircea Gradu
Published 2019-10-07 by SAE International in United States
More than 90% of new vehicles include Advanced Driving Assistance Systems that offer features such as Lane Keep Assist and Adaptive Cruise Control [1]. These ever-improving vehicle systems present a great opportunity to increase driving safety and reduce the number of roadway deaths and injuries. Indeed, they are already having a positive effect. However, the wide variety of features offered in the marketplace can be confusing to consumers, who may not clearly understand their vehicles’ true capabilities and limitations, or have an easy way of comparing system performance between vehicle models. This lack of information has the potential to reduce the safety gains of ADAS features by increasing the risk of improper use. To encourage transparency in the marketplace and thus engender the maximum positive effect of ADAS technologies, this paper proposes a five-level rating system, which utilizes diamonds to denote significant milestone achievements in vehicle system performance. The rating charts resulting from this system describe gradients of performance within criteria addressed by certain foundational ADAS features. Presented here in its initial stage of development,…
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Combined Optimization of Energy and Battery Thermal Management Control for a Plug-in HEV

FEV Italia S.R.L.-Michele Caggiano
University of Bologna-Gabriele Caramia, Nicolo Cavina, Alessandro Capancioni, Stefano Patassa
Published 2019-10-07 by SAE International in United States
This paper presents an optimization algorithm, based on discrete dynamic programming, that aims to find the optimal control inputs both for energy and thermal management control strategies of a Plug-in Hybrid Electric Vehicle, in order to minimize the energy consumption over a given driving mission. The chosen vehicle has a complex P1-P4 architecture, with two electrical machines on the front axle and an additional one directly coupled with the engine, on the rear axle. In the first section, the algorithm structure is presented, including the cost-function definition, the disturbances, the state variables and the control variables chosen for the optimal control problem formulation. The second section reports the simplified quasi-static analytical model of the powertrain, which has been used for backward optimization. For this purpose, only the vehicle longitudinal dynamics have been considered. The third section describes the Model-in-the-Loop environment of the vehicle, implemented in Simulink. In particular, the validation of the fuel consumption and the battery temperature models against experimental data is shown, and the original control strategies for the energy and thermal management…
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Turbocharger Thermal Transfer Model Initialization: Quasi-Adiabatic Map Calculation

Ecole Centrale De Nantes-Guillaume Goumy, Pierre Marty, Pascal Chesse, Nicolas Perrot, Rémi Dubouil, Georges Salameh
Published 2019-10-07 by SAE International in United States
To comply with the evermore stringent polluting emission regulation, such as Euro 6c and its new homologation WTLP cycle, the use of turbochargers, already high in Diesel engines, is steeply rising in Gasoline ones. Turbochargers come into a large variety of implementations such as single/two stage(s) or even parallel. In the meantime, car manufacturers intend to decrease development cost and time by using more and more simulation over experimental measurements. However, usual turbocharger models have not followed this trend of modernity.While the heating part of the standard driving test cycle becomes a major topic, turbocharger models are still map based, built from turbocharger manufacturer’s data and measured only in hot conditions. To improve their accuracy, new turbocharger models need to take into account the thermal transfers. The phenomenon has been widely studied, and different models have been proposed to solve this problem but they require specific data for their calibration. This is hardly compatible with the industry habits.Deriving from an initial turbocharger model with thermal transfer, this paper presents a method to evaluate quasi-adiabatic turbine…
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Optical Spray Investigations on OME3-5 in a Constant Volume High Pressure Chamber

FEV Europe GmbH-Sandra Glueck, Markus Schoenen
RWTH Aachen Univ.-Christian Honecker, Marcel Neumann, Stefan Pischinger
Published 2019-10-07 by SAE International in United States
Oxygenated fuels such as polyoxymethylene dimethyl ethers (OME) offer a chance to significantly decrease emissions while switching to renewable fuels. However, compared to conventional diesel fuel, they have lower heating values and different evaporation behaviors which lead to differences in spray, mixture formation as well as ignition delay. In order to determine the mixture formation characteristics and the combustion behavior of neat OME3-5, optical investigations have been carried out in a high-pressure-chamber using shadowgraphy, mie-scatterlight and OH-radiation recordings. Liquid penetration length, gaseous penetration length, lift off length, spray cone angle and ignition delay have been determined and compared to those measured with diesel-fuel over a variety of pressures, temperatures, rail pressures and injection durations. Liquid penetration lengths for OME3-5-sprays were found to be shorter than that of diesel-fuel analogues, while lift-off-lengths were generally observed to be longer for OME3-5, resulting in longer gaseous mixing lengths. As the cetane numbers suggested, ignition delay was found to be shorter for OME3-5. Spray cone angles were reduced at low temperature and wider at high temperature, while gaseous penetration…
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Effects of Prechamber on Efficiency Improvement and Emissions Reduction of a SI Engine Fuelled with Gasoline

Istituto Motori CNR-Paolo Sementa, Francesco Catapano, Silvana Di Iorio, Bianca Maria Vaglieco
Published 2019-10-07 by SAE International in United States
The permanent aim of the automotive industry is the further improvement of the engine efficiency and the simultaneous pollutant emissions reduction.The aim of the study was the optimization of the gasoline combustion by means of a passive prechamber. This analysis allowed the improvement of the engine efficiency in lean-burn operation condition too. The investigation was carried out in a commercial small Spark Ignition (SI) engine fueled with gasoline and equipped with a proper designed passive prechamber.It was analyzed the effects of the prechamber on engine performance, Indicated Mean Effective Pressure, Heat Release Rate and Fuel Consumption were used. Gaseous emissions were measured as well. Particulate Mass, Number and Size Distributions were analyzed. Emissions samples were taken from the exhaust flow, just downstream of the valves. Four different engine speeds were investigated, namely 2000, 3000, 4000 and 5000 rpm. Stoichiometric and lean conditions at full load were considered in all tests. 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…
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Analysis of the Impact of the WLTP Procedure on CO2 Emissions of Passenger Cars

European Commission Joint Research-Biagio Ciuffo, Georgios Fontaras
Politecnico di Torino-Giuseppe DiPierro, Federico Millo, Claudio Cubito
Published 2019-10-07 by SAE International in United States
Until 2017 in Europe the Type Approval (TA) procedure for light duty vehicles for the determination of pollutant emissions and fuel consumption was based on the New European Driving Cycle (NEDC), a test cycle performed on a chassis dynamometer. However several studies highlighted significant discrepancies in terms of CO2 emissions between the TA test and the real world, due to the limited representativeness of the test procedure. Therefore, the European authorities decided to introduce a new, up-to date, test procedure capable to closer represent real world driving conditions, called Worldwide Harmonized Light Vehicles Test Procedure (WLTP). This work aims to analyze the effects of the new WLTP on vehicle CO2 emissions through both experimental and simulation investigations on two different Euro 5 vehicles, a petrol and a diesel car, representatives of average European passenger cars. The study also considers the effect of the engine warm-up and the impact of the start-stop technology in this new TA scenario. Since the WLTP imposes higher test mass and Road Loads (RLs), as well as higher driving cycle dynamics,…
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A Coupled Lattice Boltzmann-Finite Volume Method for the Thermal Transient Analysis of an Air-Cooled Li-Ion Battery Module for Electric Vehicles with Porous Media Insert Modeled at REV Scales

University of Rome Niccolò Cusano-Daniele Chiappini, Laura Tribioli
University of Rome Tor Vergata-Gino Bella
Published 2019-10-07 by SAE International in United States
Lithium ion batteries are the most promising candidates for electric and hybrid electric vehicles, owe to their ability to store higher electrical energy. As a matter of fact, in automotive applications, these batteries undergo frequent and fast charge and discharge processes, which are associated to internal heat generation, which in turns causes temperature increase. Thermal management is therefore crucial to keep temperature in an appropriate level for safe operation and battery wear prevention.In a recent work authors have already demonstrated the capabilities of a coupled lattice Boltzmann-Finite Volume Method to deal with thermal transient of a three-dimensional air-cooled Li-ion battery at different discharging rates and Reynolds numbers. Here, in order to improve discharge thermal capabilities and reduce temperature levels of the battery itself, a layer of porous medium is placed in contact with the battery so to replace a continuum solid aluminum layer. Many studies, which have already demonstrated how the porous media can improve thermal performance of heat exchange systems, are present in recent literature. There is a large number of models for representing…
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