Large Eddy Simulations (LES) towards a comprehensive understanding of Ducted Fuel Injection concept 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 and numerical simulations, at medium-low computational cost, showed that the duct adop- tion 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 mod- elling 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 pur- poses, is of paramount importance for a robust knowledge on the DFI physical behavior. In this context, the present work exploits the potential of Large Eddy Simulations (LES) to analyze 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 exten- sive amount of experimental data related to both free spray and DFI, has been employed. 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. The relia- bility of this methodology has been herein proven, highlighting an impressive runtime saving without any remarkable worsening of the accuracy level. Thanks to this approach, a detailed description of the main DFI-enabled soot mitigation mechanisms has been achieved, bridging the still open knowledge gap in the physical understanding of the impact of spray-duct interaction

Comparison Between Different Hydrogen Fuelled Powertrains for Urban Busses

In the compelling need for the decarbonization of the transport sector, hydrogen could play a crucial role, especially in heavy duty applications where the limited specific energy of chemical batteries can significantly reduce either the payload or the operative range. Moreover, the possibility to use Hydrogen not only within Fuel Cells (FCs) systems but also as a fuel in Internal Combustion Engines (ICEs) makes it even more attractive for future sustainable transport systems. In such a framework, this work aims to compare, through numerical simulation, different hydrogen powertrain configurations designed for an urban bus application. In particular, a series hybrid architecture was chosen as a reference considering three different technologies for its Auxiliary Power Unit: two internal combustion engines fuelled with Diesel and Hydrogen respectively, and a Fuel Cell featuring almost the same power level of the internal combustion engines. The study was carried out in real world driving condition and it showed the benefits of both hydrogen powertrains on the vehicle fuel economy. Finally, in order to provide a more comprehensive overview, an analysis of the Total Cost of Ownership (TCO) was performed demonstrating that the H2-engine could achieve a significant improvement of the powertrain efficiency with investments and operating costs closer to the Diesel configuration

A New Generation of Hydrogen-Fueled Hybrid Propulsion Systems for the Urban Mobility of the Future

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

How future surgery will benefit from SARS-COV-2-related measures: a SPIGC survey conveying the perspective of Italian surgeons

COVID-19 negatively affected surgical activity, but the potential benefits resulting from adopted measures remain unclear. The aim of this study was to evaluate the change in surgical activity and potential benefit from COVID-19 measures in perspective of Italian surgeons on behalf of SPIGC. A nationwide online survey on surgical practice before, during, and after COVID-19 pandemic was conducted in March-April 2022 (NCT:05323851). Effects of COVID-19 hospital-related measures on surgical patients' management and personal professional development across surgical specialties were explored. Data on demographics, pre-operative/peri-operative/post-operative management, and professional development were collected. Outcomes were matched with the corresponding volume. Four hundred and seventy-three respondents were included in final analysis across 14 surgical specialties. Since SARS-CoV-2 pandemic, application of telematic consultations (4.1% vs. 21.6%; p < 0.0001) and diagnostic evaluations (16.4% vs. 42.2%; p < 0.0001) increased. Elective surgical activities significantly reduced and surgeons opted more frequently for conservative management with a possible indication for elective (26.3% vs. 35.7%; p < 0.0001) or urgent (20.4% vs. 38.5%; p < 0.0001) surgery. All new COVID-related measures are perceived to be maintained in the future. Surgeons' personal education online increased from 12.6% (pre-COVID) to 86.6% (post-COVID; p < 0.0001). Online educational activities are considered a beneficial effect from COVID pandemic (56.4%). COVID-19 had a great impact on surgical specialties, with significant reduction of operation volume. However, some forced changes turned out to be benefits. Isolation measures pushed the use of telemedicine and telemetric devices for outpatient practice and favored communication for educational purposes and surgeon-patient/family communication. From the Italian surgeons' perspective, COVID-related measures will continue to influence future surgical clinical practice

Study of the synthesis of CeO2 nanoparticles for their use in CO preferential oxidation (COPrOx)

CeO2 nanoparticles were synthesized by the controlled precipitation method from a Ce(NO3)3 solution. To this end, two additives were used alternatively: ethylene glycol (EG) and tetramethylammonium hydroxide (TMAH). Their function was to reduce the particle size obtained after the synthesis. After precipitation and drying, nitrate and organic residuals must be removed, and the method employed for this step could affect the structure and size of the particles. This is an important issue for achieving contaminant-free measurements in catalytic tests. In order to optimize the residuals removing process, a thorough study of the species present and/or eliminated was carried out. Our findings show that a calcination temperature of at least 500 C is necessary in order to accomplish the complete removal of solvent and precursors such as NO 3 . Among the catalysts studied, the one prepared with EG showed the best activity for CO preferential oxidation. In order to study the effect of the residuals upon the catalytic activity, samples prepared using EG were calcined at different temperatures and tested for the COPrOx reaction. CO conversions for all the samples were between 80% and 93% at different temperatures. The best activity was obtained with the sample calcined at 500 C, which is in agreement with the minimum temperature necessary for the total elimination of residuals.Fil: Peiretti, Leonardo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; ArgentinaFil: Tiscornia, Ines Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones En Catalisis y Petroquímica "ing. Jose Miguel Parera"; Argentin

CeO2 and Co3O4-CeO2 nanoparticles: effect of the synthesis method on the structure and catalytic properties in COPrOx and methanation reactions

CeO2 and Co3O4–CeO2 nanoparticles were synthesized, thoroughly characterized, and evaluated in the COPrOx reaction. The CeO2 nanoparticles were synthesized by the diffusion-controlled precipitation method with ethylene glycol. A notably higher yield was obtained when H2O2 was used in the synthesis procedure. For comparison, two commercial samples of CeO2 nanoparticles (Nyacol®)—one calcined and the other sintered—were also studied. Catalytic results of bare CeO2 calcined at 500 °C showed a strong influence of the method of synthesis. Despite having similar BET area values, the CeO2 synthesized without H2O2 was the most active sample. Co3O4–CeO2 catalysts with three different Co/(Co + Ce) atomic ratios, 0.1, 0.3, and 0.5, were prepared by the wet impregnation of the CeO2 nanoparticles. TEM and STEM observations showed that impregnation produced mixed oxides composed of small CeO2 nanoparticles located both over the surface and inside the Co3O4 crystals. The mixed oxide catalysts prepared with a cobalt atomic ratio of 0.5 showed methane formation, which started at 200 °C due to the reaction between CO2 and H2. However, above 250 °C, the reaction between CO and H2 became important, thus contributing to CO elimination with a small H2 loss. As a result, CO could be totally eliminated in a wide temperature range, from 200 to 400 °C. The methanation reaction was favored by the reduction of the cobalt oxide, as suggested by the TPR experiments. This result is probably originated in Ce–Co interactions, related to the method of synthesis and the surface area of the mixed oxides obtained.Fil: Peiretti, Leonardo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Navascués, Nuria. Universidad de Zaragoza. Instituto de Nanociencia de Aragón; EspañaFil: Tiscornia, Ines Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Hydrogen Powertrains: A Comparison Between Different Solutions for an Urban Bus

In the compelling need for the decarbonization of the transport sector, hydrogen could play a crucial role, especially in heavy duty applications where the limited specific energy of chemical batteries can significantly reduce either the payload or the operative range. Moreover, the possibility to use Hydrogen not only within Fuel Cells (FCs) systems but also as a fuel in Internal Combustion Engines (ICEs) makes it even more attractive for future sustainable transport systems. In such a framework, this work aims to compare, through numerical simu- lation, different hydrogen powertrain configurations designed for an urban bus application. In particular, a series hybrid architecture was chosen as a reference considering three different technologies for its Auxiliary Power Unit: two internal combustion engines fuelled with Diesel and Hydrogen respectively, and a Fuel Cell featuring almost the same power level of the internal combustion engines. The study was carried out in real world driving conditions and the results were also compared with the ones of a conventional diesel powertrain. In particular, the numerical analysis highlighted an evident gain in terms of fuel consumption and overall efficiencies for both FCEV and H2-ICE, with respect to conventional and hybrid diesel powertrains. Based on the present results, further developments will be devoted to the optimization of the hybrid control strategy for a cost-effective exploitation of the hydrogen fueled configurations

Unravelling the hydrogen absorption process in Pd overlayers on a Au(111) surface

The hydrogen absorption into overlayers of Pd deposited on Au(111) has been investigated by density functional theory (DFT). Hydrogen concentrations, absorption environments, and geometrical and electronic effects have been analyzed, seeking for a better understanding of the general principles governing the process and the effect of foreign supports. The results show that the absorption is more favored than in pure Pd leading to lower absorption energies and less repulsive interactions due to the surface expansion induced by the gold larger lattice constant. Our findings also suggest that the hydrogen absorption process is more favorable for a less number of Pd overlayers. This situation changes gradually until the substrate influence is no longer detected and the pure palladium nature appears. An entangled combination of repulsive forces, strain effect, structural ordering and chemical affinity has been found. The kinetics of hydrogen absorption has been studied as well. Two cases were explored: (1) the absorption of an adsorbed hydrogen atom and (2) the bond-breaking and penetration of a H2 molecule.Fil: Quaino, Paola Monica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada e Ingeniería Electroquímica; ArgentinaFil: Nazmutdinov, Renat. Kazan National Research Technological University; RusiaFil: Peiretti, Leonardo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada e Ingeniería Electroquímica; ArgentinaFil: Santos, Elizabeth del Carmen. Ulm University; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin