bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluid dynamic analysis of a cryogenic piston pump
Authors: Cioni Stefano , Balduzzi Francesco , Romani Luca , Bianchini Alessandro , Ferrara Giovanni 
Published: December 2022

Abstract
Cryogenic piston pumps are commonly found in cryogenic systems to pressurize low-temperature liquefied fuels, such as liquified natural gas (LNG) or hydrogen, which are then gasified and stored in high-pressure vessels. The main challenges to be tackled in the design of these machines concern the low operating temperatures, high discharge pressures, and especially the need to avoid liquid evaporation, as this can lead to a reduction of volumetric efficiency or even to the shutdown of the pump. Two effects can cause the formation of vapor bubbles: cavitation, i.e., when the static pressure falls below the saturation value during the suction phase, and evaporation due to a temperature increase of the cryogenic liquid.
In this study, a numerical analysis of a cryogenic single-piston pump is carried out. In the first part of the activity, the suction phase is studied through three-dimensional, steady-state CFD simulations. The performance of the pump in terms of pressure losses is evaluated and possible improvements to the suction geometry are identified.
Then, two-phase steady-state Eulerian-Eulerian simulations are performed. The Rayleigh-Plesset model is used in order to evaluate the onset of cavitation. The minimum inlet pressure conditions that avoid cavitation are identified for two different geometries underlining the positive effect of the introduced modifications. Results show that the methodology applied in this work can lead to improvements in cryogenic pump design, reducing the static pressure losses and hence limiting the risk of cavitation.
Optimized size and schedule of the power-to-hydrogen system connected to a hydrogen refuelling station for waste transportation vehicles in Valle Camonica
Authors: Vincenti Ferdinando , Cominini Paride , Furlanetto Dario , Sorlini Antonio , Valenti Gianluca 
Published: December 2022

Abstract
The aim of this work is the implementation of an optimization model for a hydrogen production facility connected to a refuelling station for heavy-duty vehicles, operating in the field of waste management and transportation. The model is composed by two subsequent mixed integer linear programming problems. The first problem addresses the problem of vehicle refuelling schedule and the second deals with the plant design and operation. The outputs of the model are the design and operation parameters of the plant and the vehicle refuelling schedule, allowing for the minimum levelized cost of hydrogen. Different possibilities for the electricity supply are investigated: grid electricity, solar photovoltaic and hydroelectric. The most profitable option is the installation of a 10 MW solar photovoltaic field, with a connected 3.3 MW Electrolyzer and 3700 kg storage. The resulting levelized cost of hydrogen is 10.24 €/kg. If no revenues from the sold electricity are considered, buying electricity from the grid becomes the most cost-effective option. The electrolyzer and storage size for this case are 760 kW and 405 kg, with a levelized cost of hydrogen of 13.75 €/kg. A sensitivity analysis, performed on the latter case, shows that the most sensible input parameters are the electrolyzer specific consumption and the cost of the electricity. A statistical analysis is also performed, considering a randomized failure distribution, obtaining the optimal values for the electrolyzer capacity of 700-800 kW and a hydrogen storage size of 1300-1400 kg. The costs, considering current electricity prices and no subsidies, are still high for hydrogen penetration in the energy market.
Electrochemical Impedance Spectroscopy study on ammonia-fed Solid Oxide Fuel Cells
Authors: Cinti G. , Baldinelli A. , Bidini G. , Barelli L. 
Published: December 2022

Abstract
The use of ammonia as a fuel is one of the promising pathways to decarbonize the energy sector. When ammonia is converted into power in the so-called “Ammonia-to-Power”, the most interesting technology is the Solid Oxide Fuel Cell (SOFC) that can operate directly with ammonia and reach high performance in terms of efficiency. SOFCs are a high-efficiency and, potentially, low-cost technology, but still suffer from degradation issues related to internal losses. An innovative experimental technique to evaluate losses evolution caused by degradation is electrical impedance spectroscopy (EIS), followed by measurement data post-processing through the Distribution of Relaxation Times (DRT) analysis. In this study, a single SOFC is studied with a combined EIS and DRT methodology, when operating with a gas mixture of hydrogen, nitrogen and ammonia. The results identify the contribution to DRT of fuel dilution and the internal ammonia decomposition reaction.
Techno-economic study on green hydrogen production and use in hard-to-abate industrial sectors
Authors: Superchi F , Mati A , Pasqui M , Carcasci C , Bianchini A 
Published: December 2022

Abstract
Replacing the bulk of grey hydrogen needed by industrial processes with a green one is one of the challenges of energy transition. In this study, the problem is analyzed from the perspective of a pre-determined amount of hydrogen to be delivered to hard-to-abate industries (steel mills and chemical industries) and produced by a wind farm converted or specifically installed for the scope. A hybrid configuration of the resulting energy system is figured out, considering a wind farm of twelve utility-scale turbines (2.3 MW each, for a total of 28 MW) to be coupled with alkaline-type electrolyzers, Li-Ion batteries and a hydrogen storage system. Moreover, it is assumed that the plant can also get energy grid in specific conditions, thus not producing a 100% green hydrogen in transitory periods. Specific point of strengths of the analysis are represented by the availability of several-year wind power production data, industrial performance data for the electrolyzers, whose model also accounts for performance degradation due to temperature, realistic operational constraints and variable efficiency. A battery aging model is also considered. A techno-economic analysis for different plant configurations is carried out with the aim of assessing how the systems performs form an economic and environmental point of view. Results show that is feasible to feed the plant with a constant hydrogen flow rate at a levelized cost of hydrogen (LCOH) of 4.95 €/kg with a green index (GI) around 64%, while a configuration that may reach higher GI (70%) presents a higher LCOH (5.26 €/kg).
Numerical investigation on a thermoelectric generator in an exhaust automotive line with convergent metal foam
Authors: Buonomo B. , Cascetta F. , di Pasqua A. , Fiorito C. , Manca O. 
Published: December 2022

Abstract
In the present paper, a 2-D steady state convective heat transfer problem in a convergent channel partially filled with aluminum foam with an external thermoelectric generator (TEG) component is numerically solved. The channel is characterized by a length equal to 272 mm and by a height of 60 mm. The TEG has the dimensions equal to 65 mm and 8.5 mm. The investigation is executed considering the Darcy-Forchheimer-Brinkman assumption and the local thermal equilibrium (LTE) hypothesis for modelling the metal foam. The exhaust gas is considered to have the same properties of the air in corresponding to the assigned temperature of the upper surface of the thermoelectric generator. The thermophysical properties are temperature independent and the thermoelectric generator is studied as a solid with an internal energy generation. The governing equations for gas, porous media and thermoelectric generator are solved by finite volume method using the Ansys-Fluent code. Different configurations of convergent metal foam are analyzed. The aluminum foams are characterized by 5 PPI and porosity equal to 0.905, 0.946 and 0.971. Results are presented in terms of temperature distributions, thermoelectric efficiency, power density, and the Energy Performance Ratio (EPR) for different gas flow rates and aluminum foam configurations. Furthermore, a comparison with the use of the same foam samples characterized by a constant section is showed for the same system. From the comparison, it is possible to deduce how the configuration with convergent channel has a more uniform temperature profile than the geometry with constant section.
Improvements to the hybrid method applied to the design of plate-finned tube evaporators
Authors: Starace G , Macchitella S , Colangelo G 
Published: December 2022

Abstract
The advantage of designing plate-finned tube evaporators applying the hybrid method is to combine low computational costs with the accurate results guaranteed by the use of predictive functions based on results of either numerical, or analytical, or experimental analysis. The high flexibility of the method makes it suitable for use as an effective design tool for evaporators in a wide range of operating conditions. This paper tells about improvements and refinements to the hybrid method algorithm performed to make it even more flexible and consistent with real heat exchangers performance prediction, depending on configuration changes. Part of the algorithm code has been changed in order to extend the application range of the model and several tests have been performed by varying the operating conditions such as the temperature difference between refrigerant and air at the inlet as well as the air relative humidity. The results show how the model is sensitive to the working conditions variations.
Predictive model of cooling system for railway electric propulsion: validation of design choices and last mile analysis
Authors: De Rosa R , Belli L , Frosina E , Venanzio P , Romagnuolo L , Senatore A 
Published: December 2022

Abstract
For many years the most advanced railway propulsion systems have been based on the use of electric motors. Compared to the other available solutions, these are characterized by greater operating economy and less environmental pollution. In order to operate as efficiently as possible and to guarantee the high standards of electromechanical reliability, these propulsion technologies need adequate cooling systems to operate in controlled temperature conditions. Considering this, the implementation of increasingly accurate and performing simulation models can represent a significant advantage and provide great support in the optimization phase of cooling systems, in terms of reduction of dimensions and weight, rapid and low-cost experimentation, prediction of critical scenarios and choice of the best solution strategies to be taken. In this regard, in the context of the collaboration between the University of Naples Federico II, University of Sannio and the company Hitachi Rail STS S.p.A., several lumped parameter models of power converter cooling systems for railway electric propulsion were developed in the Simcenter AMESim environment. These models allowed to validate specific design choices from thermal and hydraulic perspectives, aimed at higher energy efficiency of the system, and to perform the so-called Last Mile predictive analysis, in order to evaluate the possibility of removing a vehicle from the railway line as consequence of a fault of specific components.
Application of a one-dimensional fuel-oil dilution model coupled with an empirical droplet-to-film formation strategy for predicting in-cylinder oil effects in a direct injection engine
Authors: Renzis E D , Mariani V , Bianchi G M , Falfari S , Cazzoli G 
Published: December 2022

Abstract
Nowadays climate change due to the unnatural increment of green-house effect is one of the most critical environmental issues. In this context, internal combustion engines are still a short - term valuable solution. This is made possible by the study and the development of synthetic or alternative fuels, such e - gasolines and hydrogen. In this context, direct injection is still the most adopted strategy to improve internal combustion engine efficiency. The installation of the injector on the cylinder head may lead to the impact of the fuel on the wall of the cylinder liner. This phenomenon causes lubricant oil dilution, possibly increasing particulate matter emission at low load and abnormal combustions, known as low - speed pre-ignitions, at high load. The present paper aims to evaluate the influence of a set of established key parameters anticipating the effects of lubricant oil - fuel diffusion through a one - dimensional model implemented in Python. The model accounts for the runtime deposition of the fuel film by means of the results of a three - dimensional Computational Fluid Dynamics spray simulation. The model accounts also for the heat and mass transfer between species and the liquid fuel phase change for a representative setup of nowadays injectors. The dilution of a multigrade lubricant oil caused by synthetic fuels under an engine cold start operative condition is evaluated in this work.
Numerical analysis of energy recovery system for turbocharged internal combustion engines via a parallel compounding turbine
Authors: Frigo Stefano , Francesconi Marco , Sani Luca , Antonelli Marco 
Published: December 2022

Abstract
Increasing energy efficiency requirements mandatory ask for optimizing energy utilization in many devices, which include internal combustion engines. One of the most investigated subjects is the energy recovery from the exhaust, such as turbo-compound systems, which usually consist in a secondary turbine located afterward the turbocharger. Here an alternative arrangement is proposed and analysed via a numerical model. The recovery turbine works in parallel to the main turbine and uses the gasses which would be otherwise wasted through the waste-gate valve, once the set-point boost pressure is reached. The reference case analysed is a 12.4L turbocharged diesel engine, commonly used in marine, road and light railroad applications, with a nominal power of 380kW. The results showed that an overall 8% of power can be gained, without nor increasing the fuel mass flow rate, neither requiring significant modifications to the baseline engine. Moreover, in the case of the recovery system failure, the operation of the engine is not affected, thus resulting in no engine availability reduction. This work also shows a feasible way to convert the mechanical energy delivered by the recovery turbine into electrical energy, by making use of a high-speed electrical generator.
Conceptual design and sizing optimization based on minimum energy consumption of lift-cruise type eVTOL aircraft powered by battery and fuel cell for urban air mobility
Authors: Donateo Teresa , Çinar Hasan 
Published: December 2022

Abstract
In conceptual studies and prototypes of aerial vehicles for Urban Air Mobility, batteries are generally adopted as only energy sources. However, batteries have a long charging time that is not suitable for consecutive flights, and a low energy density that limits the range and flight time of the aircraft. For this reason, the hybrid propulsion solution consisting of a battery and a fuel cell has attracted attention in aviation in recent years. This study proposes the conceptual design of a VTOL (Vertical Take-Off and Landing) aircraft for passenger transportation in metropolitan areas by the synergic optimization of the aircraft configuration and the sizing of the propulsion system aimed at minimizing the power request in cruise. In the proposed conceptual design method, VTOL type aircraft is powered by either the battery or the fuel cell according to the flight phase. A multivariate nonlinear optimization problem using as goal the minimization of the fuel cell size is solved. The optimal values of battery size, wing loading, aspect ratio, endurance speed, aircraft weight, maximum lift coefficient, disk loading, rotor solidity, and zero-lift drag coefficient are determined from the solution of the optimization problem.
Model-based optimization of Sliding Rotary Vane Pump for internal combustion engine cooling of heavy-duty vehicles
Authors: Fatigati F , Di Bartolomeo M , Pallante F , Lo Biundo G , Cipollone R 
Published: December 2022

Abstract
The reduction of CO2 and pollutant emissions of internal combustion engines (ICEs) keeping their performance close to the expectations is the main driver of the research in the transportation sector. To counteract the global warming issues international governments set strict emission limitations foreseeing severe penalties for exceeding them. The vehicle electrification surely helps to match these stringent requirements, but a net CO2 reduction can be achieved only if the electricity from the grid has low carbon content. This is not the case of most part of the Countries where the fossil fuels are still the main sources of electric energy production. Thus, considering also the still higher cost of the electric vehicles, the technological improvement of ICEs assumes a strategic importance in this transition period. Among the possible interventions ensuring to achieve this aim, the efficiency enhancement of ICE cooling pump is one of the most effective. As matter of fact, it is proven that the replacement of conventional centrifugal pump with Sliding Rotary Vane Pumps (SVRPs) lead to an interesting decrease of fuel consumption and CO2 emissions. Nevertheless, the design of this machines is not straightforward due to the complex thermo-fluid-dynamic phenomena taking place inside their chambers. This aspect is even more critical for wide operating range as in the case of heavy-duty vehicles. Here, high pump revolution speeds could be provided to satisfy the flow rate requirements thus involving efficiency deterioration due to friction losses enhancement. Therefore, to reduce the revolution speed needed by the pump to elaborate the required flow rate, a novel design strategy based on the enhancement of volumetric capability is presented. The pump resulting by this design approach was called Low Speed LS pump which was prototyped and experimentally characterized over a wide set of operating conditions. The indicated cycle was also measured to better assess the fluid-dynamic behaviour of the machine. The experimental results show a maximum efficiency close to 60% in accordance with the best literature results.
Highlighting the Role of Lubricant Oil in the Development of Hydrogen Internal Combustion Engines by means of a Kinetic Reaction Model
Authors: Distaso E. , Calò G. , Amirante R. , De Palma P. , Mehl M. , Pelucchi M. , Stagni A. , Tamburrano P. 
Published: December 2022

AbstractThe urgent need to reduce the dependence on fossil fuels has re-ignited the interest toward Hydrogen Internal Combustion Engines (HICEs). Nevertheless, there are still criticalities that need to be assessed for accelerating the development of this technology. The undesired but unavoidable participation of lubricant oil to the combustion process can be the cause of many of these. Due to an extremely low autoignition resistance at low temperatures, lubricant oil is considered the main responsible for the onset of abnormal combustion modes, which need to be understood for delivering reliable and ready to market HICEs. By employing a kinetic reaction mode, this work analyses the autoignition tendency of hydrogen contaminated with n-C16H34(n-hexadecane), the latter being selected as a surrogate species representative of lubricant oil chemical characteristics. Starting from the detailed CRECK model (Version 2003), a reduced mechanism with very small size (169 species and 2796 reactions) was developed, which makes it suitable for the use in practical CFD engine simulations. Zero-dimensional numerical simulations were performed employing the reduced mechanism to quantify the variation of hydrogen ignition delay time due to the presence of different amounts of lubricant oil. Operating conditions typical of engine chambers were considered in the analysis. The results show that lubricant oil can have a significant impact on the charge reactivity, especially in the low-temperature range, with consequences that can potentially hamper the development of HICEs.
Hydrogen Fuel Cell Hybrid Electric Vehicles: the Impact of Commercial Vehicle Fleets on the Penetration of Renewable Energy Sources
Authors: Bartolucci Lorenzo , Cennamo Edoardo , Cordiner Stefano , Mulone Vincenzo , Pasqualini Ferdinando , Tatangelo Camilla 
Published: December 2022

Abstract
The transport sector is one of the most significant contributors to greenhouse gas (GHG) emissions, with the road segment accounting for large part of the emissions and requiring immediate action to address the increasing issues of climate change. To this aim, the international community is promoting technological alternatives to fossil fuel-based powertrains, thus favoring the increase in electric vehicle (EVs) penetration. However, to be sustainable the electrification of mobility requires a large share of energy produced by renewable sources to support the decarbonization process. The simultaneous increase in volatility for both the energy demand (due to EVs diffusion) and production (due to the Renewable Energy Sources RES growth), has a significant impact on the reliability of the electricity grid infrastructure. The growth of RES penetration brings an energy production increase that may not synchronized with the demand evolution, possibly leading to a grid imbalance. To this aim, the storing potential of green hydrogen, produced from RES during energy surplus periods, could allow better exploitation of the rising installed RES capacity. The proposed study aims to analyze the benefits that can arise from introducing Fuel Cell Hybrid Electric Vehicles (FCHEVs) in a commercial electric fleet in terms of environmental and grid resilience perspectives. FCHEVs are electric vehicles propelled by a hybrid powertrain, coupling electric battery packs and a fuel cell stack as energy sources; here, hydrogen is used as an energy vector stored in high-pressurized tanks. Starting from a reference scenario of a fleet composed of 10 EVs, the number of FCHEVs is progressively increased to assess their impact on the fleet performance. A set of mission scenarios for the commercial vehicles is obtained through the Markov Chain method, starting from accurate GPS data. These different scenarios are used in a numerical model to optimally plan the fleet scheduling and their configuration in terms of vehicles associated with specific missions. Results show a reduction of up to 57 % in grid fluctuations (estimated through its standard deviation) and a decrease from 77 % to 82 % in CO2 emissions concerning traditional vehicles increasing the FCHEV penetration considering the current Italian energy scenario.