bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD-3D and 1D modeling of fuel cell powertrain for a hydrogen vehicle
Authors: Marra Carmine , Corda Giuseppe , d’Adamo Alessandro 
Published: December 2023

Abstract
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.
Utilisation of Ethyl Levulinate as Diesel Fuel Additive
Authors: Frigo S , Antonelli M , Francesconi M , Galletti AM Raspolli 
Published: December 2023

Abstract
The world is going through a radical phase of energy conversion, due to both environmental and socio-economic factors, which will lead to a progressive transition from fossil to renewable energy sources. As regards the light land transport sector (cars), the abandonment of propulsion systems based on the use of internal combustion engines (ICEs) in favour of electrification seems the preferred solution. On the contrary, for heavy land (trucks and trains), marine and air transport sectors the path to follow is not yet clear.
A possible alternative to fossil fuels is certainly represented by bio-fuels, which should allow a drastic reduction of CO2 emissions and, to a lesser extent, of CO and particulate matter. The use of bio-fuels does not involve a drastic change in the systems of distribution and use of energy, as the existing infrastructures can remain unchanged. In particular, second generation bio-fuels (obtained from non-food matrices) are attracting more and more attention and, among these ones, oxygenated alcohols obtained from residual lignocellulosic biomasses appear extremely promising for the use in diesel engine.
The present study analyses the utilisation of ethyl levulinate (EL), a versatile second generation bio-fuel that can be used in Diesel/gasoline engines. EL can be conveniently obtained from the sustainable one-pot acid-catalyzed conversion of waste lignocellulosic feedstocks, employing bioethanol as the solvent/reagent.
EL has been tested in a small DI Diesel engine, blended up to 25% by volume with a commercial Diesel fuel, without significative changes in engine performance, moderately increasing NOx and HC emissions but significantly lowering soot and CO emissions by more than 50%.
Characterization of Hydrotreated Vegetable Oil (HVO) in a Euro 6 Diesel Engine as a Drop-In Fuel and With a Dedicated Calibration
Authors: d’Ambrosio S , Mancarella A , Marello O 
Published: December 2023

Abstract
Renewable fuels can play an important role in achieving future goals of energy sustainability and CO2 reduction. In particular, hydrotreated vegetable oil (HVO) represents one of the most promising alternatives to petroleum-derived diesel fuels. Several studies have shown that conventional diesel engines can run on 100% HVO without significant modifications to the hardware and control strategies. The current activity has experimentally evaluated the potential of HVO as a “drop-in” fuel, i.e., without changes to the original baseline calibration, comparing it to conventional diesel fuel on a 2.3-litre Euro 6 compression ignition engine.
Tests revealed that HVO can significantly reduce engine-out soot (by more than 60%), HC and CO emissions (by about 40%), compared to diesel, while NOx levels and fuel conversion efficiency remain relatively unchanged under steady-state warmed-up conditions. The advantages of HVO proved to be further enhanced when the engine has not yet warmed up.
Using statistical techniques of design of experiments (DoE) at three warmed-up steady-state operating points, the main engine control parameters were recalibrated to demonstrate that engine-out emissions can be further optimized with a dedicated calibration.
Analysis of the Vibrational Behavior of dual-fuel RCCI combustion in a Heavy-Duty Compression Ignited Engine fueled with Diesel-NG at Low Load
Authors: Silvagni Giacomo , Moro Davide , Ravaglioli Vittorio , Ponti Fabrizio , Corti Enrico , Brusa Alessandro , Cavina Nicoló , Narayanan Abhinandhan , Srinivasan Kalyan K. , Krishnan Sundar R. 
Published: December 2023

Abstract
In the field of internal combustion engines, the Low Temperature Combustions (LTC) appear to have the potential to reduce the formation of both soot and nitrogen oxides. One of the most promising LTC is Reactivity Controlled Compression Ignition (RCCI) which is based on the combustion of a lean low reactivity fuel-air mixture generated in the intake manifold and autoignited by small injections of high reactivity fuel introduced at high pressure in the combustion chamber. By the combination of net-zero natural gas and biodiesel, such LTC methodology might represent a suitable solution moving toward zero-emissions in transportation sector.
Despite the potential to reduce pollutant emissions, Low Temperature Combustion strategies face a challenge in controlling the angular position where the combustion takes place which can be overcome by a proper management of the high-pressure injections.
One potentially interesting application is related to trucks, mainly because they have long periods of idling, since emissions can be drastically reduced by means LTC. A single cylinder research engine for heavy duty application is operated under steady state conditions at low load and speed to analyze the possibility of controlling the engine behavior in dual fuel RCCI mode. The results indicate that the combustion mode switches from the dual-stage to gaussian within a narrow angular range. A further advance of the start of injection can generate misfires and significant variations in typical combustion indexes, while a delayed start of injection can cause impulsive combustion that rises the cylinder temperature and results in high-frequency pressure oscillations inside the combustion chamber. These oscillations are related to the combustion chamber typical resonance frequency, and if relevant in amplitude and persist for a long time, they might generate a potential source of failures.
Theoretical and experimental evaluation of electric coolant pump benefits in real driving cycles
Authors: Marco Di Bartolomeo , Davide Di Battista , Roberto Cipollone 
Published: December 2023

Abstract
Engine thermal management is a promising option to reduce fuel consumption and harmful emissions of Internal Combustion Engines. This is particularly suitable to support the transition towards a carbon-neutral transportation sector, considering that the role of combustion engines is expected to persist in the near and medium future. In this study, a prototype pump electrically actuated was compared to a mechanical pump of a downsized gasoline engine that propels a real vehicle. In the first phase of the analysis, the cooling circuit was tested from a hydraulic point of view on all its branches using an engine mounted on a bench equal to that working on the vehicle. The hydraulic circuit was fully characterized via pressure transducers and flow meters in all branches for different thermostat lifts, representing different coolant temperatures. On the same bench, the OEM pump and an electrically actuated one, suitably redesigned on an operating point more representative of the real operating conditions, were tested. A vehicle propelled with the same tested engine (having a conventional mechanically actuated pump) was run on the road following three different driving cycles. The engine revolution speeds were registered, as well as the temperature of the cooling fluid. The electric and mechanical pumps were compared using the performance maps previously obtained. The electric pump speed was set to deliver the same coolant flow rate as the OEM pump, following the same sequence of thermostat lifts. The results show that a 60 % average reduction of the pump energy consumption is possible, leading to an average specific CO2 emission reduction of 1 g/km. This result is even more relevant during urban driving, with emission savings hitting 2.5 g/km.
Hydrogen, methane and one of their fuel blends combustion: CFD analysis and numerical-experimental comparisons of fixed and mobile applications
Authors: Madia M , Cicalese G , Dalseno L 
Published: December 2023

Abstract
The capabilities of Computational Fluid Dynamics (CFD) coupled with detailed chemistry simulations are examined in both steady jet diffusion flames and in an internal combustion engine case fuelled with hydrogen. Different approaches to turbulence-chemistry interaction such as the “Laminar Flame Concept” the “Eddy Dissipation Concept” and the “Turbulent Flame Speed Closure” are considered and tested. The results are compared with the experimental data available. Concerning the jet diffusion flames, the combustion processes of hydrogen, methane and one of their fuel blends are investigated on two burner geometries. Different sensitivities (i.e. mesh, turbulence model, turbulent Schmidt number, chemical mechanism) are performed. The study demonstrates that despite the burner geometry considered and the chemical composition of the fuel, the Complex Chemistry with “Eddy Dissipation Concept” is the model that better describes the behaviour of the turbulent flames. On the other hand, the “Laminar Flame Concept” sub-model is characterized by an higher fuel consumption rate, which causes an overestimation of the temperature peak. As for the in-cylinder unsteady simulations, the hydrogen combustion process is better described by the “Turbulent Flame Speed Closure” sub-model, which, unlike the other two, requires the specification of both laminar and turbulent flame speed. Despite different variations being considered, the “Laminar Flame Concept” adoption leads to an unphysically high burning rate, while the Eddy Dissipation Concept sub-model is characterized by an underestimation of the apparent heat release rate, and thus of the pressure peak inside the combustion chamber.
Effects of a high-reflective mulching membrane on environmental parameters and food crops cultivation: results from a summer season campaign
Authors: Di Giuseppe A , Pazzaglia A , Fabbrizi G , Castellani B , Nicolini A , Rossi F , Cotana F 
Published: December 2023

Abstract
This study aims to investigate the effectiveness of an innovative technology for the agricultural sector. The technology consists of a high-reflective mulching membrane, coupled with a drip sub-irrigation system, applied in the experimental field in Perugia, Italy. The aim is to investigate the effects of the high-reflective membrane on soil temperature, food crops productivity, phenological growth, and nutritional characterization of fruits. The experimental field was set up to investigate two potential scenarios: with and without mulching membrane coupled with a drip sub-irrigation system. Temperature monitoring sensors were installed in both sections to monitor the soil temperature at 5 cm depth. The phenological monitoring campaign was performed according to the parameters defined for the cultivated food crops. Preliminary results in terms of environmental monitoring showed that the soil temperature values were lower in the section covered by the mulching membrane during the middle hours of the day. The proposed farming technology allows to increase the food crops productivity tenfold, while maintaining the nutritional properties of food crops compared to those cultivated with traditional techniques. Further analyses will be performed to investigate more in-dept the nutritional properties of the cultivated food crops to assess its effects on human health.
The maximization of shared energy in RECs in disadvantaged areas in terms of population density: the case study of Osidda in Sardinia
Authors: Angioi V. , Leoni G. , Frattolillo A. , Mastino C.C. , Baccoli R. , Ricciu R. , Pintus V. , Fiorino D. , Brundu P. 
Published: December 2023

Abstract
Even if the first examples of free associations of citizens for the exploitation of local energy resources date back to the end of the nineteenth century, it is with the EU Directive 2018/2001 RED II that the concept of Renewable Energy Community is introduced for the first time. It is an association of ordinary citizens, commercial activities, public administrations, small and medium-sized enterprises, aimed at the production and maximization of the use of energy produced on site. Alongside the social (greater energy independence, awareness of environmental issues) and environmental (promotion of renewable energy and reduction of CO2 emissions) aspects, the economic one is equally relevant in order to contribute to the dissemination of RES, maximizing its self-consumed share in the production site and therefore reducing the loads of overproduction on the transmission network.
In this paper, the authors analyze in detail the regulatory aspects and the technological solutions that are contributing to the diffusion of these communities at national level, also in the light of the recent ARERA Resolution for widespread self-consumption. The critical issues associated with their implementation in disadvantaged area in terms of population density will be discussed. The case study of the Municipality of Osidda in Sardinia will be presented, where the provision of social services and the achievement of energy independence represent the tools to combat the rapid depopulation suffered in recent years. The model developed by the authors starts from an initial careful collection of data, aimed at overcoming the problems of measuring and estimating the energy consumption of very different users (residential and public), identifying the possible solutions able to maximize the shared energy produced by RES, inside the RECs and consequently the economic return connected to national economic incentives.
Ammonia heat pumps for district heating: thermo-economic optimization analysis based on evaporator geometry for either direct expansion or chilled water configurations
Authors: Passarelli A F , Viscito L , Merlo U , Filippini S , Mauro A W 
Published: December 2023

Abstract
Electric heat pumps are recognized as a key technology for decarbonization and have received increasing policy support in several countries over the last few years. These devices offer a highly efficient form of electric heating and could make an important contribution to the transition to a low carbon future, especially in case of district heating systems. Within this context, this paper presents a thermo-economic optimization analysis of a 7.35 MW electric heat pump system employed for district heating purposes and using ammonia as working fluid. The implemented code gathers multiple sub-models calibrated ad-hoc from real data or manufacturers’ datasheets. The heat exchangers are simulated by considering phenomenological equations and well-known heat transfer coefficient and pressure drop prediction methods. The optimization analysis is performed at constant condensation temperature that guarantees in/out hot water temperatures of 30/62 °C and is focused on the matching between compressor and evaporator heat exchanger, by considering either a direct expansion system or a chilled water heat pump. Both the coefficient of performance (COP) and the set-up costs are considered as optimization performance indicators for the construction of the Pareto front.
Numerical modelling of stepped helical cooling channels
Authors: Grespan M , Trane D , Campanelli L , Angeli D , Freddi R 
Published: December 2023

Abstract
The automotive industry is in the midst of a radical change of propulsion technology to meet the increasingly stringent limits on emissions and fuel consumption. Electric and hybrid power-trains are progressively replacing their internal combustion counterparts, as they are more efficient, especially in transient operation. In electric and hybrid vehicles effective cooling system operation is of utmost importance as it influences directly the efficiency and power density levels achievable by the power train. Thus, accurate analyses are needed to maximize the thermal performance of these systems. In this work an electric motor cooling jacket, that features a stepped helical geometry, is studied by means of CFD, with a particular focus on the head losses. The periodicity of the cooling channels geometry along the helical development is exploited to reduce the computational domain to a basic periodic module. The flow field is determined by applying a 3D Finite Volume approach, and numerical solutions are obtained by means of a validated incompressible solver. Novel boundary conditions are purposely developed to allow for the coupling of the inlet and outlet patches, which are roto-translated with respect to each other. The sensitivity of integral results on friction losses, with respect to the number of periodic modules included in the model, is investigated. The developed numerical model is employed to obtain a suitable correlation for the equivalent Darcy friction factor as a function of the Reynolds number only. Finally, a first estimation of the total head losses is obtained by using the Darcy Weisbach formula along with the aforementioned friction factor correlation.
Robust Estimation of C-response of Geomagnetic Data
Authors: Tong Wanqing , Guo Rongwen , Liu Jianxin , Ji Hang 
Published: December 2023

Abstract
C-response from geomagnetic data contain information on the geoelectric structure of the deep Earth, providing an effective way to study the deep Earth structure. How to obtain high accuracy C-response from geomagnetic data is an important step in the subsequent study of the deep Earth structure, and has important practical significance for the study of the deep geoelectric structure. In order to obtain stable C-response estimates and suppress the influence of noise, this paper proposes to use the Robust C-response estimation method and apply it to the C-response estimation of actual geomagnetic station data, and the results of this estimation are most comparatively analyzed with two other traditional C-response estimations to reflect the correctness of the Robust C-response estimation method. The implementation of this method provides a methodological basis for the subsequent processing and interpretation of geomagnetic station data.
Earthquake Hazards Vulnerability Analysis of The Nankou-Sunhe Fault in Changping (Beijing) Using HVSR Method
Authors: Liu Xu , Zhao Shuai , Qian Rongyi 
Published: December 2023

Abstract
During the Holocene period, three paleoseismic events (Mw=7.7-7.9) occurred on the Nankou-Sunhe Fault in Beijing. For disaster prevention and mitigation, earthquake zoning is needed to be carried out to map the areas that will experience severe damage when an earthquake occurs. This study uses the Horizontal to Vertical Spectral Ratio (HVSR) method to obtain not only the sedimentary layer thickness and fault structure according to empirical formulas, but also the spatial variations in the peak frequency and amplification values that can explain the characteristics of the geological layer beneath the surface. Based on the calculated results, the peak frequency(f) ranges from 0.2 to 4 Hz with the lowest frequency distribution in the southwest parts, which indicates a thicker sediment layer. Amplification(A) ranges from 2 to 14 with the distribution of higher values in the southeastern and northeastern parts. The K-value (A2/f) is in the range of 0-180 and the highest K-value in the southwest of the fracture indicates that this region is at high risk for damage. Our results provide a better understanding of the earthquake hazards vulnerability of the Nankou-Sunhe Fault in Changping, Beijing, and can be used as a basis for urban disaster prevention and reduction.
Multiresolution Representation of Geoelectric Model and Parameter Operation in Wavelet Domain
Authors: Cao Xun , Guo Rongwen , Liu Jianxin , Tian Shengqi , Tong Wanqing 
Published: December 2023

Abstract
In this paper, an algorithm for wavelet domain geoelectric model representation and parameter manipulation is introduced, which can be utilized for multiresolution inversions of geophysical data based on tree structure. With proper wavelet choice, the model can be represented by much less parameters than traditional model representation, expecting to reduce the computational cost for inversion remarkably. The use of tree structure to represent the wavelet coefficients makes the parameter operations (e.g., perturbating model parameter and adding more details in a model) in inversion much simpler. Introducing detail in a model or removing detail from a model can be simply realized by adding nodes to or deleting nodes from the existing tree structure. The model parameter value can be perturbated by changing the tree node values. Our algorithm is general and can be applied to develop any geophysical inversions in wavelet domain with trivial additional work once the forward modeling and inversion algorithm is available.
The Resume of Frequency-domain Loop-loop Electromagnetic Method Inversion Applications
Authors: Sun Yishu , Wang Shengjie 
Published: December 2023

Abstract
Frequency-domain loop-loop electromagnetic method (FDLEM) inversion can be applied to ground, airborne, and borehole. This paper focuses on the two ways of inversion: model-driven and data-driven, and briefly address state-of-the-art inversion algorithms and approaches to serve as an academic reference for researchers involved in the study of FDLEM.
Study of Shearlet Domain Scale-Angle Adaptive Surface Wave Separation
Authors: Wang Tong , Wang Xingyu , Li Pei , Li Guangcai , Yong Fan 
Published: December 2023

Abstract
In the seismic data processing, high energy surface wave overlaps with effective wave, which affects the quality of seismic data imaging. The traditional frequency domain method can effectively remove surface wave, but it will damage the low frequency information of seismic data. In view of this, we proposed a scale-angle adaptive surface wave separation method based on Shearlet sparse transform. The surface wave model obtained by filtering method and the effective wave can decomposed in Shearlet domain, based on the characteristic differences between surface wave and effective wave in frequency, velocity and direction. At different scales and angles, an adaptive surface wave removal operator based on L2 norm of Shearlet coefficient is developed to remove surface wave information from seismic data. The actual seismic data application results show that compared with the traditional surface wave suppression method, the proposed method can thoroughly separate surface wave and effective wave, and obtain high quality denoising seismic data.