bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D CFD analysis of Mixture Formation in Direct-Injection Hydrogen-fueled Internal Combustion Engines
Authors: Potenza Magda Elvira Cassone , Gaballo Maria Rosaria , Arvizzigno Antonio , Anaclerio Giuseppe , Torresi Marco , Camporeale Sergio Mario 
Published: December 2022

Abstract
The European Green Deal for halving greenhouse gases emissions by 2030, compared to those of 1990s, and the resulting conversion in road transport from 2035 imply the need for the automotive field. Hydrogen-fueled internal combustion engines show a good potential to satisfy the transition towards the carbon neutrality. In particular, direct injection of hydrogen in spark-ignited internal combustion engines have great efficiency potentialities, nonetheless the design optimization of the injection systems needs extensive analysis for the evaluation of the hydrogen-air mixing processes under different engine operating conditions. Transient simulations of the gas-exchange process and fuel injection and mixing are fully described within this paper for two different commercial CFD codes namely, AVL-Fire and Ansys-Fluent. Both codes use the finite-volume approach to discretize the governing equations. Numerical results from the two commercial codes have been compared against the experimental data provided by the Argonne National Laboratories in terms of contours of fuel mole-fractions and velocity-field vectors, resulting from applying laser-based techniques on an optically accessible, single-cylinder engine.
Real Time Estimation of Combustion Indicators on a 4-Cylinder CI Turbocharged Engine Based on Instantaneous Engine Speed Measurement with Rapid Prototyping Implementation
Authors: Bosi L , Catalani I , Baroni A , Romani L , Vichi G , Bellissima A , Asai G , Minamino R , Ferrara G 
Published: December 2022

Abstract
In the field of Internal Combustion Engines (ICEs), increasingly stricter regulations on pollutant emissions have made necessary to continuously monitor engine operation. Indeed, in order to tackle fault-induced variations in engine performance, continuous, real-time data related to the engine’s thermodynamic cycle is needed: specifically, obtaining detailed information on the engine combustion phase is paramount. Combustion indicators are calculated through in-cylinder pressure, for which both direct and indirect measurement techniques can be employed. The former are accurate, but suffer from limited durability, while the latter are less accurate, but durable and less expensive, therefore more attractive for mass production applications. A technique for reconstructing the pressure cycle of each cylinder, through the combination of instantaneous crankshaft speed signal and a 0D thermodynamic model, was developed by the authors in MATLAB-Simulink environment and validated against experimental data. The objective of the present study is to implement this model on a four-cylinders CI turbocharged engine. Specifically, since focus was put on assessing the model real-time capability, efforts were made to execute the model inside a real-time controller. The paper presents the results of the experimental campaign that was carried out to validate the developed model. The signals from the pickup wheel and the camshaft phase sensor represent the main inputs, as they allow for the calculation of the engine speed and the detection of each cylinder Firing Top Dead Center (FTDC), respectively. Pressure sensors were mounted in all the cylinders for direct pressure acquisition. Tests were carried out under different operating conditions, specifically by varying speed, load and by reproducing the effects of injector malfunction in one cylinder. The developed model proved to be sensitive to operating conditions variations, correctly calculating combustion indicators such as the Indicating Mean Effective Pressure with real-time capability.
Modeling and design optimization of a hybrid power generator for full-electric naval propulsion
Authors: Saponaro Gianmarco , Stefanizzi Michele , D’Amato Davide , Franchini Emanuele , Fornarelli Francesco , Torresi Marco , Camporeale Sergio Mario 
Published: December 2022

Abstract
The purpose of this work is to build a model of diesel engine useful for studying new hybrid solutions for power generation. This kind of study is of significant interest particularly for the marine sector, due to recent limitations on fuel consumption and constraints imposed on the minimum powertrain efficiency. In this paper a variable-speed diesel generator model is presented. The model simulates both the dynamic behavior of the engine and the fuel consumption during the operating cycle. This model was developed using experimental results of bench tests conducted on the VL1716C2-MLL engine by Isotta Fraschini Motori (IFM) SpA. Diesel engine dynamics is based on the formulation found in the technical literature on mean value models and then adjusted through experimental data. Special attention was paid to developing the procedure to find the minimum specific fuel consumption for a given load. Initially, the presented resutls concern the correct response of the model under different load conditions. Then, the improvement in specific fuel consumption (obtained by adjusting the engine speed according to the load), in comparison with fixed speed operation, is shown.
A preliminary computational analysis towards the use of Electrically Heated Mixing Catalyst for innovative SCR after-treatment systems
Authors: Nappi A. , Vespertini A. , Torre A. Della , Montenegro G. , Onorati A. 
Published: December 2022

Abstract
This work aims at investigating the possible advantages of substituting the mixer in traditional SCR systems with an Electrically Heated Catalytic structure (EHC). First of all, EHC technology is being widely investigated in literature because it offers a concrete solution for catalyst thermal activation and film formation reduction in engine cold start conditions; however, its adoption as a mixer can also guarantee other important improvements in reducing pollutant emissions. In this work, a low-pressure injection of Ad-Blue impacts an electrically heated structure and a complete analysis of liquid droplets and film evaporation is carried out. A hybrid Eulerian-Lagrangian model has been adopted on a multi-region configuration, accounting for fluid-solid conjugate heat transfer (CHT), which plays a key role in the conversion strategy: it has been demonstrated that the heated structure can be exploited to significantly increase the exhaust gas enthalpy in the cold start, which represents an important improvement for pollutant conversion. Different heating strategies are analysed, with the objective of maximising the spray evaporation and the uniformity of the ammonia distribution downstream of the mixer. The objectives of this work are emphasizing the improvements that an electrically heated mixing catalyst can bring to the traditional SCR configuration, laying the foundation for other following studies.
Assessment of a desiccant cooling system in a traditional and innovative nanofluid HVAC system
Authors: Colangelo Gianpiero , Raho Brenda , Milanese Marco , Cannoletta Donato , de Risi Arturo 
Published: December 2022

Abstract
The topic of energy saving is a constant in everyday life, and it is widespread all over the world. Space heating using solar panels is the most used renewable source of energy, but the application of solar energy for cooling the fluids used for refrigeration is growing very fast. Among the techniques used for refrigeration, this work focused on Desiccant Cooling. In particular, with the use of dynamic simulation software, it was possible to study the heat supplied and the energy consumption of a Heating Ventilation Air Conditioning (HVAC) system of a university building and to compare consumption with those of a Desiccant Cooling system applied to the same building. Four different cases were simulated: two related to the HVAC system, one of which operates with water and glycol and the other one with nanofluid, and the other ones to the Desiccant Cooling system with both types of fluids mentioned above. Keeping the same energy demand of the building in all the simulations, it was found that in summer the Desiccant Cooling system had higher performance than the traditional HVAC system and that the use of the nanofluid in both types of conditioning systems further increased the performance of 21%. Simulations were carried out using TRNSYS software.
The comparative analysis of the R290 heat pump system working with standard expansion valve and two-phase ejector
Authors: Fingas R , Haida M , Smolka J , Besagni G , Palacz M , Bodys J , Nowak A J 
Published: December 2022

Abstract
The heat pump systems play a significant role in the global energy transition process of household heating sources towards zero-emission. One of the key technologies to improve the efficiency of heat pump systems utilizing natural working fluids is application of the two-phase ejector, which is able to recover part of the expansion losses. The comparative experimental analysis of a novel ejector-based air-source R290 heat pump was performed. The two two-phase bypass ejectors were installed in a R290 heat pump unit and a number of modifications were introduced to the baseline system. The adaptions included implementation of the internal heat exchanger, increasing the superheat at the compressor suction port, and a liquid separator for handling the two-phase flow at the ejector outlet. The performance evaluation of the system was based on COP and system heating capacity. The comparative analysis with the R290 heat pump utilizing standard expansion valve and two-phase ejector was carried out for typical operating conditions for its domestic application during heating seasons. The system working with an ejector as a throttling device allowed for up to 33% of COP improvement over the system utilizing an expansion valve. Additionally, the ejector implementation resulted in decreased pressure ratio of the compressor, which increased the system heating capacity by up to 90%.
Influence of the ventilation strategy on the respiratory droplets dispersion inside a coach bus: CFD approach
Authors: Scungio Mauro , Parlani Giulia , Falcucci Giacomo 
Published: December 2022

Abstract
The airborne transmission of the COVID-19 virus was considered the main cause of infection. The increasing concern about the virus spread in confined spaces, characterized by high crowding indexes and an often-inadequate air exchange system, pushes the scientific community to the design of many studies aimed at improving indoor air quality. The risk of transmission depends on several factors such as droplet properties, virus characteristics, and indoor airflow patterns. The main transmission route of the SARS-CoV-2 virus to humans is the respiratory route through small (<100 μm) and large droplets. In an indoor environment, the air exchange plays a fundamental role on the dispersion of the droplets. In this study, an integrated approach was developed to evaluate the influence of the ventilation strategy on the dispersion of respiratory droplets emitted inside a coach bus. There are no specific guidelines and standards on the air exchange rate (AER) values to be respected in indoor environments such as coach buses. The aim of this work is to analyse the influence of ventilation strategy on the respiratory droplet concentration and distribution emitted in a coach bus. Ansys FLUENT was used to numerically solve the well-known transient Navier-Stokes equations (URANS equations), the energy equation and using the Lagrangian Discrete Phase Model (DPM) approach to construct the droplet trajectories. The geometry is representative of an intercity bus, a vehicle constructed exclusively for the carriage of seated passengers. The 3D CAD model represented a coach bus with an HVAC system, within which an infected subject was present. The positions of exhaust vents and air-conditioning vents were chosen to ensure complete air circulation throughout the bus. The infected subject emitted droplets with a well-defined size distribution and mass through the mouth. The air exchange is provided in two different ways: general ventilation (from air intakes positioned along the bus windows and top side of central corridor) and personal ventilation (with air intakes for each passenger). For the general ventilation a single AER value was set (0.3 m3 s−1). The first results obtained showed a slight particle dispersion in the computational domain due to the airflow rate entered through the HVAC system, but a still elevated level of particle concentration tended to accumulate on the area near to infected subject. Additional analysis was executed to evaluate the beneficial effects linked to further addition of airflow through personal air-conditioning vents placed above every passenger’s head. The results show the importance of the use of the ventilation system inside a coach bus, highlighting how the contribution linked to of the personal air exchange rate can lead to a significant reduction of droplet concentration exposure and consequently a reduction of the risk of infection from airborne diseases.
Optimal Hybrid Ventilation Strategy to Assure Adequate Indoor Thermal Comfort and Air Quality in Educational Spaces under a Tropical Climate
Authors: Quijada María Cedeño , Solano Thasnee , Austin Miguel Chen 
Published: December 2022

Abstract
Air quality, specifically in indoor environments, has become a growing concern. In general, people tend to spend most of their lives indoors due to the growing urbanization. Indoor air quality is associated with ventilation rates, academic performance, and occupant’s health due to the presence of indoor pollutants. Exposure to these contaminants is a risk factor for people to develop the sick building syndrome. The objective of this study was to determine an optimal hybrid ventilation strategy in a tropical climate, favoring natural ventilation with different proposed strategies, varying the opening of doors and windows, the opening time, and the occupancy, among other aspects and strategies using dynamic simulation. The results were compared with in-situ measurements and surveys conducted on students in the case study. Of the proposed strategies, it was decided as optimal hybrid strategy to increase the fresh air intake from 5 L/s*person to 10 L/s*person with the use of mechanical ventilation and reduction of occupancy, this way, in addition to improving indoor air quality, the thermal comfort of the students was ensured.
Using neural networks to predict hourly energy consumptions in office and industrial buildings as a function of weather data
Authors: Martellotta Francesco , Ayr Ubaldo , Cannavale Alessandro , Liuzzi Stefania , Rubino Chiara 
Published: December 2022

Abstract
Office and industrial premises are among the most energy consuming type of buildings. Compared to residential buildings, they are characterized by more regular occupation patterns and stricter control of building systems. Under these conditions, it is expected that energy consumptions may be more easily predictable and may be significantly influenced by outdoor conditions more than by individual preferences. This may result in availability of straightforward predictions of energy use (at daily or hourly basis) which may contribute to trade energy at lower costs, make a better use of renewable energies, while balancing energy saving and occupants’ comfort. An essential contribution to the ability to easily and accurately predict energy consumptions, is given by the ever-increasing number of smart and IoT-based devices that collect data inside and outside buildings and consequently make them available for processing. Taking advantage of such data, it is worth investigating if advanced artificial intelligence methods (like neural networks and machine learning) are capable of yielding predictions of energy consumptions and, ideally, indoor conditions. For the purpose of the present paper, the dataset (including both input and output parameters) was obtained through simulation (using the popular EnergyPlus tool), including one office and one industrial reference building, and using three different climatic datasets. Finally, artificial neural networks were trained assuming daily and hourly energy consumptions (subdivided by category) as the target variable, showing that in most of the cases very accurate predictions could be obtained.
Data-driven modelling for gas consumption prediction at City Gate Stations
Authors: Cheli L , Meazzini M , Busi L , Carcasci C 
Published: December 2022

Abstract
City Gate Stations (CGS) are critical elements of Natural Gas (NG) distribution systems, as they connect national high-pressure transmission networks with local low-pressure networks. One of their main tasks is to pre-heat the gas to avoid dangerous sub-cooling due to the Joule-Thompson effect after the pressure reduction stage. For this process, significant amounts of thermal energy are required, usually obtained by burning part of the gas flow rate. This work aims to develop a data-driven model that will serve as a tool to predict and monitor the thermal consumption of the CGS. The plant chosen as a case study for this activity is in a region of central Italy. A Multiple Linear Regression (MLR) model is developed and trained, and its predictive performance is evaluated. The model results achieved an accuracy of over 95% for the coefficient of determination. The method makes it possible to create a baseline consumption model and evaluate the performance of the CGS over time using the CUSUM technique to find variations between actual and modelled gas consumption, being an essential tool for monitoring the effectiveness of the NG preheating system.
Tuning the Discrete Wavelet Transform for Power Smoothing of Wind Turbines
Authors: Bianchini Alessandro , Mannelli Andrea , Papi Francesco , Pechlivanoglou George 
Published: December 2022

Abstract
In the study, an extended sensitivity analysis is presented, which was aimed at properly tuning the parameters of an algorithm based on the Discrete Wavelet Transform (DWT) for use in power smoothing of utility-scale wind turbines coupled with batteries. More specifically, a twofold implementation is proposed, so that the proposed algorithm can operate efficiently both in real time as a control system and using historical data for the preliminary sizing of the storage system. In particular, this study addresses the correct setting of the main parameters of DTW, i. e. the level of decomposition and the mother wavelet family that generates the multi-resolution analysis (MRA). Based on real wind data of an onshore site, the following wavelet families have been analyzed: Daubechies, Coiflet, Symmlet, Biorthogonal and Reverse Biorthogonal. It is shown that, as the severe wind fluctuations that need to be smoothed are a quite sudden phenomena, in which usually the wind speed increases and then decreases quickly, all the wavelet families having a centered peak show good performance. On the other hand, it is highlighted that, once the correct choice of the mother wavelet is made, neither increasing the decomposition level nor making it adjustable in time, brings significant benefits. Finally, the discussed hypothesis has been assessed in combination with the proposed technique to extend the wavelet for online control using data mirroring, corroborating the suitability of the method for use in wind energy applications.
Derivation of Met-Ocean Conditions for the Simulation of Floating Wind Turbines: a European case study
Authors: Papi F. , Perignon Y. , Bianchini A. 
Published: December 2022

Abstract
Offshore wind turbines are subject not only to varying wind conditions during their lifetime, but also sea conditions. Therefore, in addition to wind speed, other sea-related quantities need to be considered to characterize a specific installation site. International standards suggest that, at a minimum, significant wave height, peak spectral period and wind/wave misalignment must be considered. In order to have a statistically significant description of the potential installation site, the long-term distributions of the three environmental variables must be determined. In this context, the objectives of the present work are twofold: firstly, to demonstrate the procedure trough which environmental conditions including wind and wave information can be derived using open-source tools. Secondly, an exemplary dataset is provided. The dataset is used both do demonstrate the procedure and provided as a ready-made example for use in future studies. The provided dataset is used in the EU-funded Horizon 2020 project FLOATECH.
PV-based hybrid residential microgrid with hydrogen and battery energy storage options: a Northern Italy case study
Authors: Damato A , Iamarino M. , Ferraro A , D’Angola A 
Published: December 2022

Abstract
Residential microgrids based on renewable energy sources (RES) are promising solutions for the ongoing energy transition but, at the same time, must also cope with the intermittency of the energy source and the limited energy storage capacity. To overcome such problems, RES-based microgrids usually rely on backup powering systems, such as a stable connection to the main grid or the presence of emergency electricity generators. In order to significantly increase the autonomy of the microgrid and limit the presence of backup solutions, an additional energy storage system based on hydrogen is proposed here, which complements the more classical option of energy storage in batteries. The microgrid under investigation is composed by a PV system, a lithium-ion battery for short term energy storage, and a hydrogen-based storage system composed of a PEM electrolyzer, a pressurized hydrogen tank and a low temperature PEM fuel cell stack. The system is managed by a control system which balances at each time the energy demand with the energy produced from different sources. Results reflect the role of hydrogen as efficient long-term storage option, while the battery fulfills short-terms storage needs. With properly sized components, the microgrid turns out to be fully autonomous during one year and can therefore work also in off-grid mode. The impact of an improved energy management approach is also highlighted, which may lead to increased hydrogen production and higher level of autonomy of the microgrid.