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In this study, the lithium-ion (Li-ion) battery type, which has a high-power density and utilizes lithium as the primary conductive terminal, has been employed. Within the scope of this research, a one-dimensional isothermal Li-ion battery model has been investigated under various electrolyte (both liquid and solid) and electrode materials using the COMSOL Multiphysics software. The obtained simulation results have been corroborated with information sourced from the literature and establish a foundational framework for future studies. The average range of electrolyte salt concentration in battery components is slightly higher for batteries utilizing polymer electrolytes compared to those with liquid electrolytes. During discharge at five different C-rates, Li-ion batteries with liquid electrolytes displayed higher voltage than those with polymer electrolytes. On the other hand, the one with the lithium iron phosphate (LFP) positive electrode exhibits the greatest variation in lithium concentration at the surface of the positive electrode at the end of discharge. Conversely, the battery using a LiNiO2 cathode shows the smallest surface lithium concentration variation during the same period. This pattern is similarly observed for the lithium concentration at the center of the electrode particles. The presented model can be used to explore innovative electrolyte and electrode materials to improve the design of Li-ion batteries.

As it is known the transport sector represents a major contributor to climate change. In particular, private transport contributes to the degradation of the air quality inside the cities or the residential areas. To address this issue, a progressive reduction of the use of fossil fuels as a primary energy source for these vehicles and the promotion of cleaner powertrain alternatives is in order. This study focuses on designing a fuel cell powertrain for a hydrogen-powered passenger car using numerical modeling. To this purpose, we initially modeled a base fuel cell and optimized its performance by using various materials for the bipolar plates and adjusting the platinum loading between the anode and cathode. Then, a preliminary design of the new powertrain has been proposed in order to achieve a nominal power of 100 kW and it has been tested on a WLTP 3b homologation cycle. Finally, we have been able to numerically estimate the behavior of the three main feeding line: hydrogen line, air line and cooling line. In conclusion, the obtained results demonstrate how numerical modelling can be successfully used in the design of complex systems such as those related to alternative energy. This work also provides a solid basis for the future development of increasingly efficient and environmentally friendly hydrogen vehicles.

Thermal management is critical for the safety, performance, and life cycle of lithium-ion (Li-ion) batteries. This study aims to determine the optimum settings and contribution levels of key parameters affecting the operating temperature of a three-dimensional (3D) thermal model of a cylindrical Li-ion battery. A Taguchi L9 orthogonal array was designed with four: (A) base fluid and (B) Al2O3volume fraction (Φ-Al2O3) of the nanofluid coolant, (C) battery–battery distance, and (D) inlet temperature (Tinlet), each varied on 3-level control factors. To minimize the maximum battery temperature (Tmax), the “smaller-is-better” signal-to-noise (S/N) ratio approach and Analysis of Variance (ANOVA) were applied. The S/N analysis and ANOVA revealed that the base fluid (A: 44.96%) and Tinlet (D: 36.00%) were the most dominant factors influencing the Tmax. The optimal design identified by the Taguchi method (A3-B3-C3-D1) successfully reduced the Tmax to 33.5 °C, a 29.0 °C reduction compared with the initial air-cooled reference model (62.5 °C). Furthermore, the maximum temperature rise during the 2100 s operation was reduced by approximately 62%. This optimal Tmax of 33.5 °C was even lower than the best result in the L9 array (35.5 °C), validating the strong predictive capability of the method.

In the pursuit of zero-emission mobility, hydrogen represents a promising fuel for internal combustion engines. However, its low volumetric energy density poses challenges, especially for high-performance applications where compactness and lightweight design are crucial. This study investigates the feasibility of an innovative hydrogen-fueled two-stroke opposed-piston (2S-OP) engine, targeting a specific power of 130 kW/L and an indicated thermal efficiency above 40%. A detailed 3D-CFD analysis is conducted to evaluate mixture formation, combustion behavior, abnormal combustion and water injection as a mitigation strategy. Innovative ring-shaped multi-point injection systems with several designs are tested, demonstrating the impact of injector channels’ orientation on the final mixture distribution. The combustion analysis shows that a dual-spark configuration ensures faster combustion compared to a single-spark system, with a 27.5% reduction in 10% to 90% combustion duration. Pre-ignition is identified as the main limiting factor, strongly linked to mixture stratification and high temperatures. To suppress it, water injection is proposed. A 55% evaporation efficiency of the water mass injected lowers the in-cylinder temperature and delays pre-ignition onset. Overall, the study provides key design guidelines for future high-performance hydrogen-fueled 2S-OP engines.

The energy shift towards carbon-free solutions is creating an ever-growing engineering interest in electrolytic cells, i.e., devices to produce hydrogen from water-splitting reactions. Among the available technologies, Proton Exchange Membrane (PEM) electrolysis is the most promising candidate for coping with the intermittency of renewable energy sources, thanks to the short transient period granted by the solid thin electrolyte. The well-known principle of PEM electrolysers is still unsupported by advanced engineering practices, such as the use of multidimensional simulations able to elucidate the interacting fluid dynamics, electrochemistry, and heat transport. A methodology for PEM electrolysis simulation is therefore needed. In this study, a model for the multidimensional simulation of PEM electrolysers is presented and validated against a recent literature case. The study analyses the impact of temperature and gas phase distribution on the cell performance, providing valuable insights into the understanding of the physical phenomena occurring inside the cell at the basis of the formation rate of hydrogen and oxygen. The simulations regard two temperature levels (333 K and 353 K) and the complete polarization curve is numerically predicted, allowing the analysis of the overpotentials break-up and the multi-phase flow in the PEM cell. An in-house developed model for macro-homogeneous catalyst layers is applied to PEM electrolysis, allowing independent analysis of overpotentials, investigation into their dependency on temperature and analysis of the cathodic gas–liquid stratification. The study validates a comprehensive multi-dimensional model for PEM electrolysis, relevantly proposing a methodology for the ever-growing urgency for engineering optimization of such devices.

The main purpose of this paper is the development of a CFD modelling methodology for the simulation of alkaline water electrolysis. The growing concern about climate change is pushing more and more countries to facilitate ecological transition programmes. Hydrogen perfectly fits the characteristics to become one of the main actors in many industrial sectors to reduce the emission of polluting gases in hard-to-abate sectors. In this framework, hydrogen must be produced through zero-impact technologies. Alkaline water electrolysis is the most widespread technology to produce green hydrogen, and through its CFD modelling it is possible to accurately simulate the behaviour of these components and enhance their performance. In this study, two three-dimensional models have been created representing two types of alkaline electrolysis cell: the first one is a standard laboratory configuration (wide-gap), the second one is a zero-gap type. Both models are based on a two-phase model (liquid: water and potassium hydroxide electrolyte, gas: hydrogen and oxygen) using a Euler-Euler approach to describe the gas bubble flow. With these models it has been possible to investigate how temperature and electrolyte flow rate affect the production of hydrogen, with particular emphasis on the pressure effect. Increasing the pressure at which hydrogen is produced could mean a significant reduction in storage compression costs, giving new horizons to this technology.

With the advancement of powertrain technology and progressive vehicle electrification, one of the solutions for the growing need for energy storage is batteries. A secondary battery is a device that stores electrical energy in chemical form and delivers it as electrical energy when needed (discharging), with the possibility to revert the process converting electrical to chemical energy (charging). The lithium-ion battery type used in the study offers increased energy and power density with a cell voltage of approximately 3.6 V, making it suitable for use in portable electronic devices like mobile phones and laptops. In this research, a 1D model (through-electrolyte direction) of lithium-ion battery was analysed, in which the effect of different C-rates was investigated using the battery and design module of COMSOL Multiphysics software for 0.1C, 0.5C, 1C, 2C, and 3C rates, relevant for automotive applications. The simulation results of the lithium-ion battery model constitute an important step towards the development of battery technology, allowing an understanding of the transport processes in the electrodes and electrolyte. The results revealed that under higher C-rates of operation, differences emerge in electrolyte and electrode voltage ranges, salt concentration profiles in the electrolyte, surface and center electrode particle lithium concentrations.

The large-scale adoption of fuel cells system for sustainable power generation will require the combined use of both multidimensional models and of dedicated testing techniques, in order to evolve the current technology beyond its present status. This requires an unprecedented understanding of concurrent and interacting fluid dynamics, material and electrochemical processes. In this review article, Polymer Electrolyte Membrane Fuel Cells (PEMFC) are analysed. In the first part, the most common approaches for multi-phase/multi-physics modelling are presented in their governing equations, inherent limitations and accurate materials characterisation for diffusion layers, membrane and catalyst layers. This provides a thorough overview of key aspects to be included in multidimensional CFD models. In the second part, advanced diagnostic techniques are surveyed, indicating testing practices to accurately characterise the cell operation. These can be used to validate models, complementing the conventional observation of the current–voltage curve with key operating parameters, thus defining a joint modelling/testing environment. The two sections complement each other in portraying a unified framework of interrelated physical/chemical processes, laying the foundation of a robust and complete understanding of PEMFC. This is needed to advance the current technology and to consciously use the ever-growing availability of computational resources in the next future.

Hydrogen-fueled fuel cells are considered one of the key strategies to tackle the achievement of fully-sustainable mobility. The transportation sector is paying significant attention to the development and industrialization of proton exchange membrane fuel cells (PEMFC) to be introduced alongside batteries, reaching the goal of complete de-carbonization. In this paper a multi-phase, multi-component, and non-isothermal 3D-CFD model is presented to simulate the fluid, heat, and charge transport processes developing inside a hydrogen/air PEMFC with a serpentine-type gas distributor. Model results are compared against experimental data in terms of polarization and power density curves, including an improved formulation of exchange current density at the cathode catalyst layer, improving the simulation results’ accuracy in the activation-dominated region. Then, 3D-CFD fields of reactants’ delivery to the active electrochemical surface, reaction rates, temperature distributions, and liquid water formation are analyzed, and critical aspects of the current design are commented, i.e., the inhomogeneous use of the active surface for reactions, limiting the produced current and inducing gradients in thermal and reaction rate distribution. The study shows how a complete multi-dimensional framework for physical and chemical processes of PEMFC can be used to understand limiting processes and to guide future development.

BackgroundTo report our experience in treating severely claudicant patients, employing a “nitinol-constrained” balloon (Chocolate, TriReme Medical Inc., Pleasanton, CA—USA) before drug-coated balloon (DCB) in a standardized protocol.MethodsEighty-one (84 limbs) consecutive Rutherford category (RC) 3 patients treated between December 2014 and December 2016 for superficial femoral artery (SFA) and popliteal arterial (PA) disease by nitinol-constrained balloon followed by DCB were enrolled. Bailout stenting was performed by Zilver PTX implantation. Intraoperative technical success and bailout-stenting rates were assessed as well as clinical improvement, ankle-brachial index (ABI) modification, primary patency (PP), and secondary patency (SP) rates at follow-up.ResultsSixty-eight patients (83.9%) were male and 31 (38.2%) diabetics. Fifty-five limbs (65.5%) presented occlusion (CTO); in 18 limbs CTO was longer than 150 mm. Bailout stenting rate was 9.5% (8/84). All patients completed 30-day follow-up: PP 100%, 61 patients completely asymptomatic (RC = 0). Mean follow-up was 12.3 ± 5.6 months; overall PP was 98.8%, and SP was 98.8%. At mid-term analysis, no differences in outcomes were recorded between stenosis and CTOs with a PP of 96.5 and 96%, respectively (p = 0.725). CTO length impacted early results: in cases of CTOs < 150 mm, PP was 100%, while in CTOs > 150 mm, it was 83.3% (p = 0031). ABI at 12-month was significantly higher with respect to preoperative values (p < 0.001).ConclusionsIn this preliminary experience, our protocol seems to be safe and effective in treating SFA and PA lesions in claudicant patients with satisfactory early and 12-month results.