bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternative fuels for hard-to-abate sectors: a carbon intensity assessment
Authors: Prussi M , Chiaramonti D 
Published: December 2022

Abstract
Heavy duty is a hard-to-abate segment of transport. Heavy duty freight sector includes road, maritime and the fast-growing aviation segments. Due to the need of energy dense vector, specifically for freight sector, the liquid alternative fuels are considered as the most effective short-to-medium term option to allow decarbonisation. The possibility to uptake these fuels in heavy-duty road and maritime is investigated in this paper, with the goal of highlighting the potentials and the existing bottlenecks. The eLNG and bio-LNG are considered as alternative fuel for road Heavy Duty, while hydrogen, ammonia and eDiesel have been selected for maritime. The potential GreenHouse Gases (GHG) saving for such alternative fuels are estimated on the basis of Well-to-Tank approach, and compared with the relative fossil benchmark. The results show the benefit of using LNG from residues for road sector, and potentially the maritime. Regarding the e-fuels, the GHG savings are potentially relevant, but using low carbon electricity for their production is crucial.
Techno-economic assessment of enhanced Biogas&Power-to-SNG processes with high-temperature electrolysis integration
Authors: Colbertaldo P , Guandalini G 
Published: December 2022

Abstract
Biogenic energy sources are essential elements of the decarbonization pathways, but are strongly constrained by the limited availability. In this context, Biogas&Power-to-X technologies are strongly supported as a promising solution to foster renewable power generation and drive sector coupling opportunities. This work investigates enhanced Synthetic Natural Gas (SNG) production processes for the repurposing of biogas plants. As an alternative to combined heat and power applications via internal combustion engines, the Italian legislation is supporting biogas-to-biomethane upgrading, focusing on the transport market. The proposed integrated plant scheme is a flexible solution based on Power-to-Hydrogen and methanation, able to exploit both electric and gas grid connections, enhancing biomethane production. Advanced process schemes are studied combining solid oxide electrolysers that exploit the methanation waste heat as input thermal energy and flexible PEM electrolysers that improve the part-load operation. The calculated efficiency at max load is about 55% for the Power-to-Methane block and nearly 75% for the overall integrated plant. Results show limited sensitivity of efficiency to input power variations, making the system suitable for the recovery of surplus renewable power generation.
Numerical characterization of hydrogen under-expanded jets: influence of the nozzle cross-section shape
Authors: Anaclerio Giuseppe , Capurso Tommaso , Torresi Marco , Camporeale Sergio Mario 
Published: December 2022

Abstract
This historical moment is characterized by a great awareness regarding the need to reduce the Greenhouse Gas emissions (GHG), which are responsible for the climate change and its detrimental consequences. Green hydrogen produced by means of Power-to-Gas technologies from renewables is gaining momentum as a possible clean fuel for the future mobility. In such a context, traditional injectors for hydrocarbon fuels are currently being tailored to be used with hydrogen. The short time available for the injection process leads to the employment of a high inlet pressure, resulting in the formation of an under-expanded jet. In this work, the main characteristics of these jets are analyzed by means of Computational Fluid Dynamics (CFD) for a Nozzle Pressure Ratio (NPR) equal to 10. Then, to provide insights regarding the dependence of the air-hydrogen mixing on section shape of the nozzle, comparisons have been performed by changing the nozzle cross-section (circular, rectangular, and elliptical), keeping constant the mass flow rate to highlight the different levels of axial penetration and radial spread observed when varying the aspect ratio (1.5, 5.0, 8.0).
CFD simulations of under-expanded hydrogen jets under high-pressure injection conditions
Authors: Rahantamialisoa F.N.Z , Zembi J. , Miliozzi A. , Sahranavardfard N. , Battistoni M. 
Published: December 2022

AbstractLarge-eddy simulations (LES) of hydrogen jets under highly under-expanded conditions are carried out. Computational fluid dynamics (CFD) analysis appears extremely useful to fully understand and optimize the hydrogen injection process, like in internal combustion engines. This work aims to analyze hydrogen high-pressure injection in the near-nozzle region, investigating the formation process and the structure of the Mach disks and the transition to turbulent jets, for nozzle pressure ratios (NPR) of 5.8 and 30. A real fluid model is utilized and compared against the simpler ideal gas model, for injections into an ambient pressure environment. Furthermore, hydrogen-air mixing evolution is investigated in the far-field region. Average quantities obtained from statistical analysis on LES simulations are compared with available data. The near nozzle region, except for the initial transient part, is better captured by accurate spatial discretization methods, while properly predicting far-field effects, like turbulence and acoustic effects, seems to be mostly related to time discretization schemes.
Hybrid Hydrogen production: Application of CO2 heat pump for the high-temperature water electrolysis process
Authors: Mojtahed Ali , De Santoli Livio 
Published: December 2022

Abstract
Hydrogen is considered an energy vector which ensures a pivotal role in the energy market in near future. As a subsequent, the need to provoke novel technologies and investigate the potential layouts rising from hybridization remains on the shoulder of research literature., The current work investigates the potential role of the supercritical CO2 heat pump to contribute to hydrogen production inside a hybrid energy system. The case study is a generic biogas power plant characterized by the combination of diverse hydrogen production technologies such as water electrolysis and the reforming process. Water electrolysis takes place through high (SOEC) and low-temperature(AEC) The role of the heat pump unit is defined to operate between these two technologies to recover heat losses and transfer them to high-temperature electrolysis. The performance of the CO2 cycle in the presented hybrid energy system is simulated via MATLAB SIMULINK and the effective indicators to improve its performance have been carried out.In the end, the result of the simulation shows a production rate of 19.27 kgH2/h. Furthermore, thanks to heat recovery the total thermal efficiency increases by 80%. It also reveals that the heat pump unit operates with COP in the range of 4.5 – 3.3 based on pressure ratios providing temperature in the range of 151-184 °C by fixing the cold sink input temperature and pressure at 70 °C, 75 bar respectively.
1D-3D coupled approach for the evaluation of the in-cylinder conditions for Gasoline Compression Ignition Combustion
Authors: Viscione Davide , Bianchi Gian Marco , Ravaglioli Vittorio , Falfari Stefania , Cazzoli Giulio , Silvagni Giacomo , Mariani Valerio , Corsi Marzia 
Published: December 2022

Abstract
Nowadays, progressive improvements of engine performance must be performed to reduce fuel consumption, which directly affects the amount of CO2 released in the atmosphere. For this purpose, considering modern technologies in the automotive scenario, Gasoline Compression Ignition (GCI) combustion might represent one promising solution, since it experiences high thermal efficiency of Compression Ignited (CI) engines and pollutant emission mitigation. This paper shows the first step of a project aimed at reproducing the combustion behavior of a Diesel engine running with GCI combustion by means of CFD simulations. In particular, this work presents a methodology used to reconstruct the mixing process inside the cylinder before the combustion event, since those engines are dramatically sensitive to the global and local mixture quality. Firstly, a reverse-engineering procedure aimed at generating the CAD model of the engine was performed. Afterwards, the discharge coefficients of the intake and exhaust valves through specifically designed 3D CFD simulations were determined, which was necessary due to the customized intake/exhaust line. Eventually, to reasonably reconstruct the in-cylinder state, the Rate of Heat Release (RoHR) curve, calculated from the analysis of the in-cylinder pressure signal running the engine in GCI mode, was imposed in GT-Power by means of a combination of Wiebe functions with the purpose of generating representative trends of pressure, temperature, and mass flow to properly define the domains of the CFD model.
CFD investigation of the radiative heat transfer effects on the adoption of an electrical heated catalyst to increase the abatement efficiency
Authors: Barillari Loris , Torre Augusto Della , Montenegro Gianluca , Onorati Angelo 
Published: December 2022

Abstract
The thermal transient of the after-treatment system (ATS) during the cold start and the typical urban drive low load engine operations is a crucial point for the conversion efficiency. In this context, the adoption of electrical heating is regarded as an effective solution to promote the catalytic activity and the pollutants abatement. This paper focuses on the evaluation of the radiative heat transfer affecting the operation of an electrical heated catalyst employed to increase the abatement efficiency of a standard catalyst. The modeling methodology relies on a CFD framework based on a Conjugate Heat Transfer (CHT) approach in OpenFOAM, so that a detailed characterization of the thermal transient of the different components of the exhaust line can be achieved. The electrical heating device under investigation is based on a metallic support and it is heated by the Joule effect. The distribution of the heat and its subsequent interaction with the gas flow significantly influence the catalyst operations. In this context, the CFD modeling framework has been further developed so that it is possible to accurately evaluate the radiative heat transfer in correspondence of the porous regions. The description of such features is mandatory for an accurate prediction of the maximum electrical heating device temperatures, resulting in a reliable estimation of the gas flow temperature and its subsequent interaction with the catalyst. The simulation methodology has been applied at first excluding the radiative heat transfer. Then, the developed radiation modeling is applied, so that its influence on the ATS performance can be fully evaluated.
Batteries Thermal Management for Hybrid plug-in Powertrains
Authors: Perrone D. , Falbo L. , Castiglione T. , Ficarella A. , Bova S. 
Published: December 2022

Abstract
Lithium-ion batteries have become the primary battery technology used for electric and hybrid vehicles powertrains. Battery temperature, however, is a critical factor for these devices, as it influences battery performance life-time and safety and must be preferably kept in the 15-35 °C range. A dynamic electro-thermal model of a lithium iron phosphate battery was developed. The model predicts battery voltage and temperature evolution in different operating conditions. A battery equivalent circuit model (ECM) with an open circuit voltage source, an ohmic resistance and a capacitor-resistor pair in series is adopted. The state-of-charge is determined by the Coulomb counting approach and the battery temperature is computed by carrying out an energy balance for the cell. The balance takes into account the difference between the heat generated within the cell and the heat loss to the environment. Finally a controller, which cools or heats the battery in order to keep its temperature in the desired range, was developed. The case of the battery pack of a hybrid plug-in powertrain during a WLTP cycle is simulated and the result of different environmental conditions are presented.
Effect of coil charge duration on combustion variability and flame morphology in a GDI engine working in lean burn conditions
Authors: Cecere G , Merola S S , Irimescu A , Millo F , Rolando L 
Published: December 2022

Abstract
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.
On Iso-octane Combustion with Ozone Addition under HCCI Engine-Like Conditions
Authors: D’Amato Marco , Magi Vinicio , Viggiano Annarita 
Published: December 2022

Abstract
Numerical simulations were carried out to study the influence of ozone on the Ignition Delay Time (IDT) of iso-octane/air mixtures under typical operating conditions of HCCI engines. 0-D and 2-D CFD simulations were carried out to compute IDT and to characterize compression, combustion, and expansion in an HCCI engine, respectively. A kinetic model was developed by merging a mechanism for iso-octane, a sub-mechanism for nitrogen oxides, and a sub-mechanism for ozone. The model was used to investigate iso-octane/air/ozone mixtures under typical operating conditions of HCCI engines running with very lean mixtures (equivalence ratio equal to 0.3). Parametric analyses were carried out considering different values of temperature (500 to 1200 K), pressure (15 to 40 bar) and ozone concentration (0 to 50 ppm). The results show that as ozone concentration increases IDT decreases, with a greater impact at low temperatures, and the NTC (Negative Temperature Coefficient) effect decreases. However, the reduction of IDT with ozone addition is less as ozone concentration increases, especially at low temperatures. An increased pressure, on the other hand, generally promotes faster ozone decomposition and enhances ozone effect on IDT reduction for all temperatures except in the range 760-840 K, where the opposite effect occurs due to NTC phenomenon. Finally, when temperature is very high, i.e. 1200 K, both ozone and pressure have little influence on the percentage reduction of IDT.
The state of the electrical sector in Western Balkan countries. Case study: Republic of Kosovo
Authors: Mexhuani A , Bylykbashi K , Jupaj B , Shala A , Rubini L 
Published: December 2022

Abstract
The electricity sector around the world is considered one of the most important sectors, which has a direct impact on the economic development of a country. Based on the increase in energy consumption, the crisis with the emission of high levels of harmful gases - the greenhouse effect and the expansion at the economic level of countries, electricity, namely the increase of energy capacity will remain key issues for future discussion at the global level. Electricity is the engine of the rapid economic development of a country; necessarily the well-being of citizens to access to energy sources and energy stability is a key requirement of every consumer, producer or economic operator. How much capacity do countries in the world have to respond to the increase in energy consumption in the future and what sources will be oriented so that the consequences are minimal for the environment, is a question that needs continuous detailed study and concrete approaches from relevant institutions and professionals in this field. Security in electricity supply is essential for our society and necessary for the 24/7 principle for the digital economy. The recent difficulties caused by the Covid-19 pandemic remind us of the great importance of electricity in all aspects of our lives, from the availability of medical equipment and IT systems - for work from home as a growing trend of systemizing jobs during 2020. Ensuring a secure and reliable electricity supply is of paramount importance to all countries in the world. Considering the Western Balkans as one of the regions which since the 90s most of it has been an area which has emerged from devastating wars and which have affected every sphere, including the energy sector. So, the development of the energy sector is one of the most critical issues in the Western Balkans region. Based on the considerable potential of electricity production from renewable sources, it is considered that the production of electricity from RES will create a stable and functional system of energy production by contributing to the principle of diversification of electricity production and decentralization of the power system. So, renewable energy is considered a promising method for building sustainable and resilient energy systems that provide affordable energy to boost a region economic development, reducing import dependence. The purpose of this scientific research is to discuss the development and current state of electricity production from renewable sources in the Western Balkans, with special emphasis on the Republic of Kosovo. Considering that all Western Balkan countries have set targets or targets for RES in their energy policies but not always these pre-defined targets are easily achievable in practice due to thevarious challenges facing the energy sector in this region.
Re-Powering Italian Wind Farms: a Feasibility Study from Theory to Practice
Authors: Sensi L , Melani PF , Venturi A , Giusti M , Mungo G , Tomassetti V , Bianchini A 
Published: December 2022

Abstract
The installation of new renewable power plants in Italy is currently hindered by various concurrent factors, the length of the authorization process above all. The average time to authorize a wind farm is about five and a half years, mainly due to the binding judgment of the EIA (Environmental Impact Assessment). Italy however is now in a phase where many of the first-installed wind farms are close to their end of life. In this perspective, a promising solution is given by the re-powering of existing wind farms, since they can access a simplified authorization procedure under the Legislative Decree 08/11/2021, n. 199 et seq., which reduces by one third the bureaucratic burden and it lets non-binding the evaluation of the landscape authorities. Moving from this background, the study provides a feasibility study on the re-powering of Italian wind farms. Starting from the database available at GSE (Gestore dei Servizi Energetici), a new re-powering scenario has been defined, accounting for the constraints on the site area, number and dimension of the turbines imposed by the art. 32 of Law 29/07/2021, n. 108. The effectiveness of the re-powering intervention has been evaluated in terms of energetic yield, considering the increased capacity factor of the new turbines, economic revenue and environmental footprint. To verify its feasibility on a real application, a wind farm owned by AGSM-AIM S.p.A., for which wind, terrain, and production data were available, has been selected. Different plant layouts have been analyzed in the WindPro software, and compared in terms of power, producibility and capacity factor. The feasibility of the different layouts has also been verified by on-field inspections.
Definition of the induction time for CO2 and CH4 hydrate via evaluation of the heat released during the process and the gas consumption rate.
Authors: Gambelli A M , Filipponi M , Rossi F 
Published: December 2022

Abstract
The induction period is defined as the time required to obtain a detectable quantity of hydrates during their natural or artificial production. This period includes the initial nucleation phase and part of the following massive growth phase. Several methods were thought to measure its length: the most adopted are the visual observation of the process and the direct measure of the temperature increase. However, these techniques are not always feasible and their accuracy is often low. This work deals with the definition of the induction time by considering the heat produced during the process, which is proportional to the temperature but significantly less affected by the stochastic nature of the process. In order to prove the feasibility of the process, the results were then compared with what obtained by considering the gas consumption rate to measure the induction time. The proposed method was validated for methane hydrates. The same confirmation was not possible for carbon dioxide hydrates, due to the high solubility in water of this species and the consequent overestimation of the gas consumption during the process.
Small-scale ORC-based unit for domestic micro-cogeneration operating in the temperature range of the solar thermal flat panels
Authors: Fatigati F , Bartolomeo M Di , Vittorini D , Coletta A , Carapellucci R , Cipollone R 
Published: December 2022

Abstract
CO2 emissions related to the energy demand in commercial and residential buildings account for over 15% of worldwide greenhouse gases emissions. This issue requires the development of new solutions, technologies, and energy management strategies to reduce the environmental impact of this sector. Simultaneous heat and power production, namely cogeneration, is a proven method for this purpose. Among the different power systems, Organic Rankine Cycle (ORC) plants allow the production of mechanical and electric energy using hot sources at low temperature levels. This feature allows to combine this technology with solar collectors, making it possible to exploit the thermal energy exceeding the thermal needs when the solar irradiation is high. In this paper, an experimental characterization of a Solar Organic Rankine Cycle (SORC) is presented. The hot source of the power plant is reproduced by water heated up to 120 °C by two 12 kW electric resistances and stored in a buffer tank with a capacity of 200 L. The 1 kW ORC unit is equipped with a scroll volumetric expander operating off-grid. The main control variable of the unit is the pump speed which is varied in each operating condition to guarantee a superheating degree at the expander inlet. Since the variability of the solar source is a critical issue in these applications, off-design operating conditions have been tested, showing the capability of the plant to be also operated far from the design point. The maximum efficiency of the unit reached 4.7 % while the highest net power was 400 W. A further test conducted to evaluate the transient performances of the unit demonstrated its small inertia and the capability of the expander to produce power right after the unit activation.