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The H2-ICE project aims at developing, through numerical simulation, a new generation of hybrid powertrains featuring a hydrogen-fueled Internal Combustion Engine (ICE) suitable for 12 m urban buses in order to provide a reliable and cost-effective solution for the abatement of both CO2 and criteria pollutant emissions. The full exploitation of the potential of such a traction system requires a substantial enhancement of the state of the art since several issues have to be addressed. In particular, the choice of a more suitable fuel injection system and the control of the combustion process are extremely challenging. Firstly, a high-fidelity 3D-CFD model will be exploited to analyze the in-cylinder H2 fuel injection through supersonic flows. Then, after the optimization of the injection and combustion process, a 1D model of the whole engine system will be built and calibrated, allowing the identification of a "sweet spot" in the ultra-lean combustion region, characterized by extremely low NOx emissions and, at the same time, high combustion efficiencies. Moreover, to further enhance the engine efficiency well above 40%, different Waste Heat Recovery (WHR) systems will be carefully scrutinized, including both Organic Rankine Cycle (ORC)-based recovery units as well as electric turbo-compounding. A Selective Catalytic Reduction (SCR) aftertreatment system will be developed to further reduce NOx emissions to near-zero levels. Finally, a dedicated torque-based control strategy for the ICE coupled with the Energy Management Systems (EMSs) of the hybrid powertrain, both optimized by exploiting Vehicle-To-Everything (V2X) connection, allows targeting H2 consumption of 0.1 kg/km. Technologies developed in the H2-ICE project will enhance the know-how necessary to design and build engines and aftertreatment systems for the efficient exploitation of H2 as a fuel, as well as for their integration into hybrid powertrains. [ABSTRACT FROM AUTHOR]

In a context in which the connectivity level of last-generation vehicles is constantly on the rise, the combined use of Vehicle-To-Everything (V2X) connectivity and autonomous driving can provide remarkable benefits through the synergistic optimization of the route and the speed trajectory. In this framework, this paper focuses on vehicle ecodriving optimization in a connected environment: the virtual test rig of a premium segment passenger car was used for generating the simulation scenarios and to assess the benefits, in terms of energy and time savings, that the introduction of V2X communication, integrated with cloud computing, can have in a real-world scenario. The Reference Scenario is a predefined Real Driving Emissions (RDE) compliant route, while the simulation scenarios were generated by assuming two different penetration levels of V2X technologies. The associated energy minimization problem was formulated and solved by means of a Variable Grid Dynamic Programming (VGDP), that modifying the variable state search grid on the basis of the V2X information allows to drastically reduce the DP computation burden by more than 95%. The simulations show that introducing a smart infrastructure along with optimizing the vehicle speed in a real-world urban route can potentially reduce the required energy by 54% while shortening the travel time by 38%. Finally, a sensitivity analysis was performed on the biobjective optimization cost function to find a set of Pareto optimal solutions, between energy and travel time minimization. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Although Hybrid Electric Vehicles (HEVs) represent one of the key technologies to reduce CO2 emissions, their effective potential in real world driving conditions strongly depends on the performance of their Energy Management System (EMS) and on its capability to maximize the efficiency of the powertrain in real life as well as during Type Approval (TA) tests. Attempting to close the gap between TA and real world CO2 emissions, the European Commission has decided to introduce from September 2017 theWorldwide Harmonized Light duty Test Procedure (WLTP), replacing the previous procedure based on the New European Driving Cycle (NEDC). The aim of this work is the analysis of the impact of different driving cycles and operating conditions on CO2 emissions and on energy management strategies of a Euro-6 HEV through the limited number of information available from the chassis dyno tests. The vehicle was tested considering different initial battery State of Charge (SOC), ranging from 40% to 65%, and engine coolant temperatures, from -7 °C to 70 °C. The change of test conditions from NEDC to WLTP was shown to lead to a significant reduction of the electric drive and to about a 30% increase of CO2 emissions. However, since the specific energy demand of WLTP is about 50% higher than that of NEDC, these results demonstrate that the EMS strategies of the tested vehicle can achieve, in test conditions closer to real life, even higher efficiency levels than those that are currently evaluated on the NEDC, and prove the effectiveness of HEV technology to reduce CO2 emissions. [ABSTRACT FROM AUTHOR]

Plug-in hybrid electric vehicles (pHEVs) could represent the stepping stone to move towards a more sustainable mobility and combine the benefits of electric powertrains with the high range capability of conventional vehicles. Nevertheless, despite the huge potential in terms of CO2 emissions reduction, the performance of such vehicles has to be deeply investigated in real world driving conditions considering also the CO2 production related to battery recharge which, on the contrary, is currently only partially considered by the European regulation to foster the diffusion of pHEVs. Therefore, this paper aims to assess, through numerical simulation, the real performance of a test case pHEV, the energy management system (EMS) of which is targeted to the minimization of its overall CO2 emissions. The paper highlights, at the same time, the relevance of the CO2 production related to the battery recharge from the power grid. Different technologies mixes used to produce the electricity required for the battery recharge are also taken into account in order to assess the influence of this parameter on the vehicle CO2 emissions. Finally, since the operating cost still represents the main driver in orienting the customer's choice, an alternative approach for the EMS, targeted to the minimization of this variable, is also analyzed. [ABSTRACT FROM AUTHOR]

In the upcoming years, more challenging CO2 emission targets along with the introduction of more severe Real Driving Emissions limits are expected to foster the development and the exploitation of innovative technologies to further improve the efficiency of automotive Spark Ignition (SI) engines. Among these technologies, Water Injection (WI), thanks to its knock mitigation capabilities, can represent a valuable solution, although it may significantly increase the complexity of engine design and calibration. Since, to tackle such a complexity, reliable virtual development tools seem to be mandatory, this paper aims to describe a quasi-dimensional approach to model a Port Water Injection (PWI) system integrated in a Turbocharged Direct Injection Spark Ignition (T-DISI) engine. Through a port-puddling model calibrated with 3D-CFD data, the proposed methodology was proven to be able to properly replicate transient phenomena of water wall film formation, catching cycle by cycle the amount of water that enters into the cylinder and is therefore available for knock mitigation. Moreover, when compared with experimental measurements under steady state operating conditions, this method showed good capabilities to predict the impact of the water content on the combustion process and on the knock occurrence likelihood. [ABSTRACT FROM AUTHOR]

In this paper, an integrated and automated methodology for the coupling between 1D- and 3D-CFD simulation codes is presented, which has been developed to support the design and calibration of new diesel engines. The aim of the proposed methodology is to couple 1D engine models, which may be available in the early stage engine development phases, with 3D predictive combustion simulations, in order to obtain reliable estimates of engine performance and emissions for newly designed automotive diesel engines. The coupling procedure features simulations performed in 1D-CFD by means of GT-SUITE and in 3D-CFD by means of Converge, executed within a specifically designed calculation methodology. An assessment of the coupling procedure has been performed by comparing its results with experimental data acquired on an automotive diesel engine, considering different working points, including both part load and full load conditions. Different multiple injection schedules have been evaluated for part-load operation, including pre and post injections. The proposed methodology, featuring detailed 3D chemistry modeling, was proven to be capable assessing pollutant formation properly, specifically to estimate NOx concentrations. Soot formation trends were also well-matched for most of the explored working points. The proposed procedure can therefore be considered as a suitable methodology to support the design and calibration of new diesel engines, due to its ability to provide reliable engine performance and emissions estimations from the early stage of a new engine development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]