Energy management system optimization based on an LSTM deep learning model using vehicle speed prediction

The energy management of a Hybrid Electric Vehicle (HEV) is a global optimization problem, and its optimal solution inevitably entails knowing the entire mission profile. The exploitation of Vehicle-to-Everything (V2X) connectivity can pave the way for reliable short-term vehicle speed predictions. As a result, the capabilities of conventional energy management strategies can be enhanced by integrating the predicted vehicle speed into the powertrain control strategy. Therefore, in this paper, an innovative Adaptation algorithm uses the predicted speed profile for an Equivalent Consumption Minimization Strategy (A-V2X-ECMS). Driving pattern identification is employed to adapt the equivalence factor of the ECMS when a change in the driving patterns occurs, or when the State of Charge (SoC) experiences a high deviation from the target value. A Principal Component Analysis (PCA) was performed on several energetic indices to select the ones that predominate in characterizing the different driving patterns. Long Short-Term Memory (LSTM) deep neural networks were trained to choose the optimal value of the equivalence factor for a specific sequence of data (i.e., speed, acceleration, power, and initial SoC). The potentialities of the innovative A-V2X-ECMS were assessed, through numerical simulation, on a diesel Plug-in Hybrid Electric Vehicle (PHEV) available on the European market. A virtual test rig of the investigated vehicle was built in the GT-SUITE software environment and validated against a wide database of experimental data. The simulations proved that the proposed approach achieves results much closer to optimal than the conventional energy management strategies taken as a reference

Real CO2 emissions benefits and end user’s operating costs of a plug-in Hybrid Electric Vehicle

Although plug-in Hybrid Electric Vehicles (pHEVs) can be considered a powerful technology to promote the change from conventional mobility to e-mobility, their real benefits, in terms of CO2 emissions, depend to a great extent on the average efficiency of their Internal Combustion Engine and on the energy source mix which is used to supply the electrical demand of pHEV. Furthermore the operating cost of the vehicle should also be taken into account in the design process, since it represents the main driver in the customer’s choice. This article has the purpose of assessing, through numerical simulations, the effects of different technology mixes used to produce electrical energy for the battery recharging, of different Internal Combustion Engines on the pHEV performance, and highlighting the main differences with respect to the regulatory test procedure

Numerical Investigation on mixture formation and combustion process of innovative piston bowl geometries in a swirl-supported light-duty diesel engine

In recent years, several innovative diesel combustion systems were developed and optimized in order to enhance the air and injected fuel mixing for engine e-ciency improvements and to mitigate the formation of fuel-rich regions for soot emissions reduction. With these aims, a three-dimensional computational fl uid dynamics (3D-CFD) numerical study was carried out in order to evaluate the impact of three di erent piston bowl geometries on a passenger car four-cylinder diesel engine, 1.6 liters. Once the numerical model was validated considering the baseline re-entrant bowl, two inno vative bowl geometries were defi ned: one based on the stepped-lip bowl; the other including a number of radial bumps equal to the nozzle holes number. Firstly, the rated power engine operating condition was investigated under nonreacting conditions to evaluate the piston bowl e ects on the in-cylinder mixing. Results highlight for both the innovative piston bowls better air utilization with respect to the re-entrant bowl: The stepped-lip bowl creates a dual toroidal vortex leading to a higher air/fuel mixing, while the radial-bumps bowl signifi cantly a ects the jet-To-jet interaction and promotes the recirculation of the fuel jet downstream to the bump, where the available oxygen enhances the mixing rate. After that, the combustion analysis was carried out for both rated power and partial-load engine operating conditions. Results confi rmed that thanks to the better air-fuel mixing, the combustion process can be improved thanks to the innovative bowl designs, both increasing the engine e-ciency at full-load condition and minimizing the engine-out soot emissions at partial-load operating point

A Methodology for the Reverse Engineering of the Energy Management Strategy of a Plug -In Hybrid Electric Vehicle for Virtual Test Rig Development

Nowadays, the need for more sustainable mobility is fostering powertrain electrification as a way of reducing the carbon footprint of conventional vehicles. On the other side, the presence of multiple energy sources significantly increases the powertrain complexity and requires the development of a suitable Energy Management System (EMS) whose performance can strongly affect the fuel economy potential of the vehicle. In such a framework, this article proposes a novel methodology to reverse engineer the control strategy of a test case P2 Plug-in Hybrid Electric Vehicle (PHEV) through the analysis of experimental data acquired in a wide range of driving conditions. In particular, a combination of data obtained from On-Board Diagnostic system (OBD), Controller Area Network (CAN)-bus protocol, and additional sensors installed on the High Voltage (HV) electric net of the vehicle is used to point out any dependency of the EMS decisions on the powertrain main operating variables. Furthermore, the impact that Vehicle-to-Infrastructure (V2I) connections have on the control law is assessed on several tests performing the same real-world route with the vehicle navigation system alternatively switched on and off. Finally, a virtual test rig of the tested vehicle, developed in the GT- SUITE environment, is used to validate the set of extracted rules against the experimental data. An error of about 1-2% on the prediction of the vehicle CO2 emissions and good matching of the State of Charge (SoC) profile in both Charge Depleting (CD) and Charge Sustaining (CS) phases prove the effectiveness of the proposed methodology

Numerical investigation of 48 V electrification potential in terms of fuel economy and vehicle performance for a lambda-1 gasoline passenger car

Real Driving Emissions (RDE) regulations require the adoption of stoichiometric operation across the entire engine map for downsized turbocharged gasoline engines, which have been so far generally exploiting spark timing retard and mixture enrichment for knock mitigation. However, stoichiometric operation has a detrimental effect on engine and vehicle performances if no countermeasures are taken, such as alternative approaches for knock mitigation, as the exploitation of Miller cycle and/or powertrain electrification to improve vehicle acceleration performance. This research activity aims, therefore, to assess the potential of 48 V electrification and of the adoption of Miller cycle for a downsized and stoichiometric turbocharged gasoline engine. An integrated vehicle and powertrain model was developed for a reference passenger car, equipped with a EU5 gasoline turbocharged engine. Afterwards, two different 48 V electrified powertrain concepts, one featuring a Belt Starter Generator (BSG) mild-hybrid architecture, the other featuring, in addition to the BSG, a Miller cycle engine combined with an e-supercharger were developed and investigated. Vehicle performances were evaluated both in terms of elasticity maneuvers and of CO2 emissions for type approval and RDE driving cycles. Numerical simulations highlighted potential improvements up to 16% CO2 reduction on RDE driving cycle of a 48 V electrified vehicle featuring a high efficiency powertrain with respect to a EU5 engine and more than 10% of transient performance improvement

Numerical Assessment on the Influence of Engine Calibration Parameters on Innovative Piston Bowls Designed for Light-Duty Diesel Engines

The optimization of the piston bowl design has been shown to have a great potential for air–fuel mixing improvement, leading to significant fuel consumption and pollutant emissions reductions for diesel engines. With this aim, a conventional re-entrant bowl for a 1.6 L light-duty diesel engine was compared with two innovative piston designs: a stepped-lip bowl and a radial-bumps bowl. The potential benefits of these innovative bowls were assessed through 3D-CFD simulations, featuring a calibrated spray model and detailed chemistry. To analyse the impact of these innovative designs, two different engine operating conditions were scrutinized, corresponding to the rated power and a partial load, respectively. Under the rated power engine operating condition, a start of injection sensitivity was then carried out to assess the optimal spray–wall interaction. Results highlighted that, thanks to optimal injection phasing, faster mixing-controlled combustion could be reached with both the innovative designs. Moreover, the requirements in terms of swirl were also investigated, and a higher swirl ratio was found to be necessary to improve the mixing process, especially for the radial-bumps design. Finally, at part-load operating conditions, different exhaust gas recirculation (EGR) rates were analysed for two injection pressure levels. The stepped-lip and radial-bumps bowls highlighted reduced indicated specific fuel consumption (ISFC) and soot emissions values over different rail pressure levels, guaranteeing NOx control thanks to the higher EGR tolerance compared with the re-entrant bowl. The results suggested the great potential of the investigated innovative bowls for improving efficiency and reducing emissions, thus paving the way for further possible optimization through the combination of these designs

Effect of coil charge duration on combustion variability and flame morphology in a GDI engine working in lean burn conditions

Spark ignition (SI) and subsequent flame front development exert a significant influence on cyclic variability of internal combustion engines (ICEs). The increasing exploitation of lean air-fuel mixtures in SI engines to lower fuel consumption and CO2 emissions is driving the scientific community towards the search for innovative combustion strategies. Moreover, although lean combustion has been widely investigated and an important number of studies is already present in literature, the high cyclic variability typical of this combustion process still represents a major hinder to its exploitation. This study aims to investigate the effects of increasing ignition energy on combustion characteristics of lean mixtures. Tests were performed on an optically accessible gasoline direct injection (GDI) engine that allowed to investigate the correlation between the thermodynamic results and spark arc-flame morphology. Engine speed was fixed at 2000 rpm, a relative air fuel ratio (AFRrel) of about 1.3 was selected and ignition timing was set at 12 crank angle degrees (CAD) bTDC. Coil charge duration was swept from 10 to 40 CAD. Two intake pressure levels were investigated, the first corresponding to wide open throttle under naturally aspirated operating mode, the second with an intake pressure of 1.2 bar, thus corresponding to a boosted operating condition. Two dedicated scripts built using NI Vision were employed for image processing, allowing the evaluation of temporal and spatial evolution of the early stages of combustion. Arc elongation and flame front contour were used as correlation parameters that characterize flame kernel inception and development. The results confirm that, as expected, the increase of the coil charge duration tends to reduce cyclic variability in terms of engine output. The optical investigations revealed that for both examined cases the standard deviation related to the wrinkling effect on flame edge at CA5 decreased as the coil charge duration increased

Dynamique de l'or et d'autres minéraux lourds dans un profil d'altération cuirassé du Burkina Faso, Afrique de l'Ouest : intérêt pour l'interprétation de la mise en place des matériaux constituant les cuirasses de haut glacis

Le profil d'altération cuirassé de haut glacis, développé dans l'environnement du site aurifère de Gangaol, a subi des phases d'altération suffisamment intenses pour que des minéraux résistants, comme le zircon et l'or, présentent des traces de dissolution importantes. Dans l'horizon supérieur de la cuirasse, ces minéraux altérés coexistent avec des particules d'or conservant des formes primaires intactes et avec des sulfures sains. Au sein de cet horizon, les teneurs en particules d'or sont plus élevées dans la matrice que dans les nodules fortement indurés. Cela implique qu'à ce niveau, le cuirassement a affecté un matériau contenant des éléments de nature et de degré d'altération variés. L'absence d'or dans la partie médiane du profil confirme un certain degré d'allochtonie des matériaux parentaux de l'horizon supérieur de la cuirasse. (Résumé d'auteur

Exploiting the potential of large eddy simulations (LES) for ducted fuel injection investigation in non-reacting conditions

The diesel combustion research is increasingly focused on ducted fuel injection (DFI), a promising concept to abate engine-out soot emissions in compression-ignition engines. A large set of experiments carried out in constant volume vessel and numerical simulations, at medium-low computational cost, showed that the duct adoption in front of the injector nozzle activates several soot mitigation mechanisms, leading to quasi-zero soot formation in several engine-like operating conditions. However, although the simplified CFD modelling so far played a crucial role for the preliminary understanding of DFI technology, a more accurate turbulence description approach, combined with a large set of numerical experiments for statistical purposes, is of paramount importance for a robust knowledge of the DFI physical behaviour. In this context, the present work exploits the potential of large eddy simulations (LES) to analyse the non-reacting spray of DFI configuration compared with the unconstrained spray. For this purpose, a previously developed spray model, calibrated and validated in the RANS framework against an extensive amount of experimental data related to both free spray and DFI, has been employed. The tests have been carried out considering a single-hole injector in an optical accessible constant volume vessel, properly replicated in the simulation environment. This high-fidelity simulation model has been adapted for LES, firstly selecting the best grid settings, and then carrying out several numerical experiments for both spray configurations until achieving a satisfying statistical convergence. With this aim, the number of independent samples for the averaging procedure has been increased exploiting the axial symmetry characteristics of the present case study. Thanks to this approach, a detailed description of the main DFI-enabled soot mitigation mechanisms has been achieved, shrinking the knowledge gap in the physical understanding of the impact of spray-duct interaction

Numerical Assessment of Additive Manufacturing-Enabled Innovative Piston Bowl Design for a Light-Duty Diesel Engine Achieving Ultra-Low Engine-Out Soot Emissions

The design of diesel engine piston bowls plays a fundamental role in the optimization of the combustion process, to achieve ultra-low soot emissions. With this aim, an innovative piston bowl design for a 1.6-liter light-duty diesel engine was developed through a steel-based additive manufacturing (AM) technique, featuring both a sharp step and radial bumps in the inner bowl rim. The potential benefits of the proposed hybrid bowl were assessed through a validated three-dimensional computational fluid dynamics (3D-CFD) model, including a calibrated spray model and detailed chemistry. Firstly, the optimal spray targeting was identified for the novel hybrid bowl over different injector protrusions and two swirl ratio (SR) levels. Considering the optimal spray targeting, an analysis of the combustion process was carried out over different engine working points, both in terms of flame-wall interaction and soot formation. At rated power engine operating conditions, the hybrid bowl highlighted faster mixing-controlled combustion due to the reduced flame-to-flame interaction and the higher air entrainment into the flame front. At partial-load operating points, the hybrid bowl showed a remarkable soot reduction in comparison with the re-entrant bowl due to a more intense soot oxidation rate in the late combustion phase. Moreover, for the hybrid bowl, a robust Exhaust Gas Recirculation (EGR) tolerance was highlighted, leading to a flat soot-brake-specific oxides of nitrogen (BSNOx) trade-off. At constant BSNOx, a 70% soot reduction was achieved without any detrimental effect on fuel consumption, suggesting the high potential of the proposed innovative bowl for soot attenuation