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Polymer electrolyte membrane (PEM) fuel cells will play a crucial role in the decarbonization of the transport sector, in particular for heavy duty applications. However, performance and durability of PEMFC stacks is still a concern especially when operated under high power density conditions, as required in order to improve the compactness and to reduce the cost of the system. In this context, the optimization of the geometry of hydrogen and air distributors represents a key factor to improve the distribution of the reactants on the active surface, in order to guarantee a proper water management and avoiding membrane dehydration.

The target of the upcoming automotive emission regulations is to promote a fast transition to near-zero emission vehicles. As such, the range of ambient and operating conditions tested in the homologation cycles is broadening. In this context, the proposed work aims to thoroughly investigate the potential of post-oxidation phenomena in reducing the light-off time of a conventional three-way catalyst. The study is carried out on a turbocharged four-cylinder gasoline engine by means of experimental and numerical activities. Post oxidation is achieved through the oxidation of unburned fuel in the exhaust line, exploiting a rich combustion and a secondary air injection dedicated strategy. The CFD methodology consists of two different approaches: the former relies on a full-engine mesh, the latter on a detailed analysis of the chemical reactions occurring in the exhaust line.

SI engines fueled with hydrogen represent a promising powertrain solution to meet the ambitious target of carbon-free emissions at the tailpipe. Therefore, fast and reliable numerical tools can significantly support the automotive industry in the optimization of such technology. In this work, a 1D-3D methodology is presented to simulate in detail the combustion process with minimal computational effort. First, a 1D analysis of the complete engine cycle is carried out on the user-defined powertrain configuration. The purpose is to achieve reliable boundary conditions for the combustion chamber, based on realistic engine parameters. Then, a 3D simulation of the power-cycle is performed to mimic the combustion process. The flow velocity and turbulence distributions are initialized without the need of simulating the gas exchange process, according to a validated technique.

We present a framework for the robust optimization of the heat flux distribution for an anti-ice electro-thermal ice protection system (AI-ETIPS) and iced airfoil performance analysis under uncertain conditions. The considered uncertainty regards a lack of knowledge concerning the characteristics of the cloud i.e. the liquid water content and the median volume diameter of water droplets, and the accuracy of measuring devices i.e., the static temperature probe, uncertain parameters are modeled as uniform random variables. A forward uncertainty propagation analysis is carried out using a Monte Carlo approach. The optimization framework relies on a gradient-free algorithm (Mesh Adaptive Direct Search) and three different problem formulations are considered in this work. Two bi-objective deterministic optimizations aim to minimize power consumption and either minimize ice formations or the iced airfoil drag coefficient.

The tightening trend of regulations on the levels of admitted pollutant emissions has given a great spur to the research work in the field of combustion and after-treatment devices. Despite the improvements that can be applied to the development of the combustion process, pollutant emissions cannot be reduced to zero; for this reason, the aftertreatment system will become a key component in the path to achieving near-zero emission levels. This study focuses on the numerical analysis and optimization of different metallic substrates, specifically developed for three-way catalyst (TWC) and Diesel oxidation catalyst (DOC) applications, to improve their thermal efficiency by reducing radial thermal losses through the outer mantle. The optimization process relies on computational fluid dynamics (CFD) simulations supported by experimental measurements to validate the numerical models carried out under uncoated conditions, where chemical reactions do not occur.

The reduction of the catalyst light-off time at the engine cold start represents a key factor for the pollutant emissions control from vehicles tested on homologation cycles and real drive conditions. The adoption of heating strategies to increase the temperature of the catalytic substrate in the early phase of the engine start is regarded as a promising solution. The present study focuses on the application of electrical heated catalyst (EHC) in an after-treatment line for a spark-ignition gasoline engine. The analysis is carried out by means of an advanced CFD framework, which includes the modeling of catalytic reactions in the substrates and accounts for the thermal evolution of all the components included in the after-treatment system.

The paper illustrates and validates a novel predictive combustion model for the estimation of performances and pollutant production in CI engines. The numerical methodology was developed by the authors for near real-time applications, while aiming at an accurate description of the air mixing process by means of a multi-zone approach of the air-fuel mass. Charge stratification is estimated via a 2D representation of the fuel spray distribution that is numerically derived by an axial one-dimensional control-volume description of the direct injection. The radial coordinate of each control volume is reconstructed a posteriori by means of a local distribution function. Fuel mass clustered in each zone is further split in ‘liquid’, ‘unburnt’ and ‘burnt’ sub-zones, given the local properties of the fuel spray control volumes with respect to space-time location of modelled ignition delay, liquid length, and flame lift-off.

In the next years, the upcoming emission legislations are expected to introduce further restrictions on the admittable level of pollutants from vehicles measured on homologation cycles and real drive tests. In this context, the strict control of pollutant emissions at the cold start will become a crucial point to comply with the new regulation standards. This will necessarily require the implementation of novel strategies to speed-up the light-off of the reactions occurring in the after-treatment system, since the cold start conditions are the most critical one for cumulative emissions. Among the different possible technological solutions, this paper focuses on the evaluation of the potential of a burner system, which is activated before the engine start. The hypothetical burner exploits the lean combustion of an air-gasoline mixture to generate a high temperature gas stream which is directed to the catalyst section promoting a fast heating of the substrate.

Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon as the most common alloying element. Despite the excellent castability and machinability of Aluminum-Silicon alloys (AlSix), anodization is often required in order to increase its corrosion resistance. This is particularly true in Chlorides-rich environments where Aluminum can easily corrode. Even if anodization process is known for almost 100 years, anodization of AlSix -based materials is particularly challenging due to the presence of eutectic Silicon precipitates. These show a poor electric conductivity and a slow oxidation kinetics, leading to inhomogeneous anodic layers. Continuous research and process optimization are required in order to develop anodic layers with enhanced morphological and electrochemical properties, targeting a prolonged resistance of brake calipers under endurance corrosive tests (e.g. >1000 hours Neutral Salt Spray (NSS) tests).

In recent years, the increase of gasoline fuel injection pressure is a way to improve thermal efficiency and lower engine-out emissions in GDI homogenous combustion concept. The challenge of controlling particulate formation as well in mass and number concentrations imposed by emissions regulations can be pursued improving the mixture preparation process and avoiding mixture inhomogeneity with ultra-high injection pressure values up to 100 MPa. The increase of the fuel injection pressure in GDI homogeneous systems meets the demand for increased injector static flow, while simultaneously improves the spray atomization and mixing characteristics with consequent better combustion performance. Few studies quantify the effects of high injection pressure on transient gasoline spray evolution. The aim of this work was to simulate with OpenFOAM the spray morphology of a commercial gasoline injected in a constant volume vessel by a prototypal GDI injector.

Selective Catalytic Reduction (SCR) systems are nowadays widely applied for the reduction of NOx emitted from Diesel engines. The typical process is based on the injection of aqueous urea in the exhaust gases before the SCR catalyst, which determines the production of the ammonia needed for the catalytic reduction of NOx. However, this technology is affected by two main limitations: a) the evaporation of the urea water solution (UWS) requires a sufficiently high temperature of the exhaust gases and b) the formation of solid deposits during the UWS evaporation is a frequent phenomenon which compromise the correct operation of the system. In this context, to overcome these issues, a technology based on the injection of gaseous ammonia has been recently proposed: in this case, ammonia is stored at the solid state in a cartridge containing a Strontium Chloride salt and it is desorbed by means of electrical heating.

A multi-objective optimal design of a brushless DC electric motor for a brake system application is presented. Fifteen design variables are considered for the definition of the stator and rotor geometry, pole pieces and permanent magnets included. Target performance indices (peak torque, efficiency, rotor mass and inertia) are defined together with design constraints that refer to components stress levels and temperature thresholds, not to be surpassed after heavy duty cycles. The mathematical models used for optimization refer to electromagnetic field and related currents computation, to thermo-fluid dynamic simulation, to local stress and vibration assessment. An Artificial Neural Network model, trained with an iterative procedure, is employed for global approximation purposes. This allows to reduce the number of simulation runs needed to find the optimal configurations. Some of the Pareto-optimal solutions resulting from the optimal design process are analysed.

The accurate prediction of pollutant emissions generated by IC engines is a key aspect to guarantee the respect of the emission regulation legislation. This paper describes the approach followed by the authors to achieve a strict numerical coupling of two different 1D modeling tools in a co-simulation environment, aiming at a reliable calculation of engine-out and tailpipe emissions. The main idea is to allow an accurate 1D simulation of the unsteady flows and wave motion inside the intake and exhaust systems, without resorting to an over-simplified geometrical discretization, and to rely on advanced thermodynamic combustion models and kinetic sub-models for the calculation of cylinder-out emissions. A specific fluid dynamic approach is then used to track the chemical composition along the exhaust duct-system, in order to evaluate the conversion efficiency of after-treatment devices, such as TWC, GPF, DPF, DOC, SCR and so on.

This work describes the development of a computational model for the CFD simulation of compact heat exchangers applied for the oil cooling in internal combustion engines. Among the different cooler types, the present modeling effort will be focused on liquid-cooled solutions based on offset strip fins turbulators. The design of this type of coolers represents an issue of extreme concern, which requires a compromise between different objectives: high compactness, low pressure drop, high heat-transfer efficiency. In this work, a computational framework for the CFD simulation of compact oil-to-liquid heat exchangers, including offset-strip fins as heat transfer enhancer, has been developed. The main problem is represented by the need of considering different scales in the simulation, ranging from the characteristic size of the turbulator geometry (tipically μm - mm) to the full scale of the overall device (typically cm - dm).

The transient heat transfer behavior of an automotive catalytic converter has been simulated with OpenFOAM in 1D. The model takes into consideration the gas-solid convective heat transfer, axial wall conduction and heat capacity effects in the solid phase, but also the chemical reactions of CO oxidation, based on simplified Arrhenius and Langmuir-Hinshelwood approaches. The associated parameters are the results of data in literature tuned by experiments. Simplified cases of constant flow rates and gas temperatures in the catalyst inflow have been chosen for a comprehensive analysis of the heat and mass transfer phenomena. The impact of inlet flow temperatures and inlet flow rates on the heat up characteristics as well as in the CO emissions have been quantified. A dimensional analysis is proposed and dimensionless temperature difference and space-time coordinates are introduced.

In this paper, computation fluid dynamics (CFD) simulations are performed to describe the effect of in-cylinder flow structures on the formation and oxidation of soot in a swirl-supported light-duty diesel engine. The focus of the paper is on the effect of swirl motion and injection pressure on late cycle soot oxidation. The structure of the flow at different swirl numbers is studied to investigate the effect of varying swirl number on the coherent flow structures. These coherent flow structures are studied to understand the mechanism that leads to efficient soot oxidation in late cycle. Effect of varying injection pressure at different swirl numbers and the interaction between spray and swirl motions are discussed. The complexity of diesel combustion, especially when soot and other emissions are of interest, requires using a detailed chemical mechanism to have a correct estimation of temperature and species distribution.

The Computational Chemistry Consortium (C3) is dedicated to leading the advancement of combustion and emissions modeling. The C3 cluster combines the expertise of different groups involved in combustion research aiming to refine existing chemistry models and to develop more efficient tools for the generation of surrogate and multi-fuel mechanisms, and suitable mechanisms for CFD applications. In addition to the development of more accurate kinetic models for different components of interest in real fuel surrogates and for pollutants formation (NOx, PAH, soot), the core activity of C3 is to develop a tool capable of merging high-fidelity kinetics from different partners, resulting in a high-fidelity model for a specific application. A core mechanism forms the basis of a gasoline surrogate model containing larger components including n-heptane, iso-octane, n-dodecane, toluene and other larger hydrocarbons.

The increasing diffusion of gasoline direct injection (GDI) engines requires a more detailed and reliable description of the phenomena occurring during the fuel injection process. As well known the thermal and fluid-dynamic conditions present in the combustion chamber greatly influence the air-fuel mixture process deriving from GDI injectors. GDI fuel sprays typically evolve in wide range of ambient pressure and temperatures depending on the engine load. In some particular injection conditions, when in-cylinder pressure is relatively low, flash evaporation might occur significantly affecting the fuel-air mixing process. In some other particular injection conditions spray impingement on the piston wall might occur, causing high unburned hydrocarbons and soot emissions, so currently representing one of the main drawbacks of GDI engines.

Oxygen enriched air (EA) is a well known industrial mixture in which the content of oxygen is higher respect the atmospheric one, in the range 22-35%. Oxygen EA can be obtained by desorption from water, taking advantage of the higher oxygen solubility in water compared to the nitrogen one, since the Henry constants of this two gases are different. The production of EA by this new approach was already studied by experimental runs and theoretical considerations. New results using salt water are reported. EA promoted combustion is considered as one of the most interesting technologies to improve the performance in diesel engines and to simultaneously control and reduce pollution. This paper explores, by means of 3-dimensional computational fluid dynamics simulations, the effects of EA on the performance and exhaust emissions of a high-speed direct-injection diesel engine.

In the last years, as a response to the more and more restrictive emission legislation, new devices (SRC, DOC, NOx-trap, DPF) have been progressively introduced as standard components of modern after-treatment system for Diesel engines. In addition, the adoption of electrical heating is nowadays regarded with interest as an effective solution to promote the light-off of the catalyst at low temperature, especially at the start-up of the engine and during the low load operation of the engine typical of the urban drive. In this work, a state-of-the-art 48 V electrical heated catalyst is considered, in order to investigate its effect in increasing the abatement efficiency of a standard DOC. The electrical heating device considered is based on a metallic support, arranged in a spiral layout, and it is heated by the Joule effect due to the passage of the electrical current.