bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Heat Content of Exhaust Gases from a Heavy-Duty Diesel Engine under Real-world Driving Conditions and Cold Start Operation
Authors: Donateo Teresa , Cutuli Paolo , Vilotta Niccolò , Algieri Angelo , Morrone Pietropaolo 
Published: December 2024

Abstract
European Commission is currently working on defining new Euro 7 standards for light and heavy-duty vehicles, which will set severe restrictions on emissions in real driving conditions, and under cold-start operations. It is well known that about 60% of fuel energy converted in a diesel engine is lost in exhaust flow, coolant, and other forms of loss. A more efficient vehicle usage can be achieved by exploiting such dissipated energy content to produce additional mechanical or electrical energy. Several solutions can be adopted for Waste Heat Recovery (WHR) systems. Among them, exploiting the synergy between Organic Rankine Cycles (ORCs), thermal storage with Phase Change Materials (PCM), and electric hybridization is the solution adopted in the research project IRIDESCENT (biodIesel hybRID Electric buS with waste heat reCovEry aNd sTorage). The efficacy of recovering heat content from exhaust gases in reducing fuel consumption has already been demonstrated under stationary conditions. However, one of the challenges in applying WHRs to the powertrain of road vehicles is the fast dynamics of the engine load that determines fast variations in the flow rate and temperature of the exhaust gases. This makes it difficult to optimize energy recovery and explains the need to adopt PCM thermal storage systems. In this framework, the goal of the present work is to characterize the variability of temperature and flow rate in the exhaust gases of a diesel engine for heavy-duty applications under real-world driving conditions. To this end, a dataset of information retrieved from the scientific literature for the Isuzu FTR850 truck was used. The dataset consists of twenty-eight trips performed with the same driver over the same route. It includes both hot-start and cold-start trips and three different values of trailer load (0, 1500, 3000 kg). For each trip, data from GPS, ambient sensors, onboard diagnostics (OBD) systems, and portable emissions measurement systems are made available with a frequency of 1 Hz. In this investigation, a statistical analysis of the data set and a preliminary selection of the ORC and PCM technologies are performed.
Techno-economic analysis of diesel, natural gas, electric and hydrogen buses
Authors: Zuccari Fabrizio , Santiangeli Adriano , Rampini Andrea , Orecchini Fabio , Bocci Enrico 
Published: December 2024

Abstract
Many regions and cities are implementing Electric (BEB – Battery Electric Bus) and hydrogen (FCB – Fuel Cell Bus) buses instead of the diesel (Diesel) and natural gas (CNG – Compressed Natural Gas) traditional ones. Many papers and reports compare the different Total Cost of Ownership of these buses but not always clarify mission, powertrain and context data. This study, starting from literature analysis, referring to a specific typical urban bus mission (17 km/h average speed per 12 h daily service), quotes techno-economic-environmental buses (purchase, maintenance, energy consumption and CO2 emissions costs), powertrains (combustion engine, battery, fuel cells, hydrogen storage) and context (diesel, CNG, electricity, hydrogen costs) data. Furthermore, a comparative analysis is carried out considering different operational scenarios based on high or low consumptions, high or low electricity costs, three hydrogen production ways and current (current, batteries and hydrogen technologies costs) and future (15% increase of diesel and CNG costs and decrease of batteries and hydrogen technologies costs) so evaluating 24 scenarios. The results shows that TCO is mainly constituted by every year costs (i.e. maintenance plus emissions and energy consumption,) respect to the one-time cost (so divided by the lifetime, i.e. purchase costs) except in the more competitive hydrogen scenarios where these 3 costs correspond equally to a 30% of the overall TCO. Thus, the bus choice, have to be made on the specific technologies and energies context costs instead on the international buses purchase cost. In fact, it is not possible to define a best technology for any scenario, especially for the future scenarios (so with a variation of diesel, CNG, battery, fuel cells, electricity and hydrogen costs). The best technology will depend on the specific context, and so specific analysis have to be made before to choose the technology to be applied. Indeed, CNG in the current scenarios is always the best technology followed by diesel, but CNG and diesel have emission costs and fossil fuel cost are expected to increase. BEB in the current and future scenarios are never the best technologies but it can be the best technology in scenarios with lower autonomy. FCB in the future scenarios are the best technology for 10 of the 12 scenarios analysed, that it is possible to say that FCB, taking into account the great possibilities of hydrogen production and the flexibility in power and energy respect the electric, even with the lower powertrain efficiencies respect to electric, is a technology that can be applied in many different contexts.
Analysis of limitations of tomographic BOS measurements in a lean H2-air premixed flame
Authors: Iapaolo F , Cozzi F , Cárdenas Barrera O F , Orlando M 
Published: December 2024

Abstract
Background Oriented Schlieren (BOS) is an optical technique that visualizes and quantifies refractive index gradients in transparent media, used extensively in studying compressible flows, heat transfer, and combustion. The refractive index field can be converted to a density field using the Lorentz-Lorenz or Gladstone-Dale equations. Recently, the tomographic version of BOS has gained attention for its application in these fields. Sipkens et al. proposed the ARAP method for tomographic BOS, which improves reconstruction accuracy by accounting for light rays converging at the camera pinhole, a common setup with entocentric lenses. This study aims to assess the limitations of tomographic BOS reconstruction using numerical simulations of an axisymmetric hydrogen Bunsen flame, comparing the results with experimental BOS measurements. It has been observed that the constant composition assumption (i.e., assuming a unique value of the Gladstone-Dale constant independently from composition) may introduce some limited errors, whereas the implementation of the ARAP algorithm has a negligible impact on the computation of temperature distribution.
Temperature monitoring strategy for microclimate prediction in low-automation greenhouses: a preliminary analysis
Authors: Miserocchi Lorenzo , Caposciutti Gianluca , Franco Alessandro , Tellini Bernardo 
Published: December 2024

Abstract
Climate control strategies in low-automation greenhouses typically rely on the measurements from a single sensor. Indeed, implementing more complex monitoring devices and sensor networks may increase investment costs without necessarily improving profitability. This paper presents a low cost and low complexity temperature monitoring strategy, which is illustrated in a case study of tomato cultivation during the mid-season in a traditional Mediterranean greenhouse located in Pisa, Italy. The objective is to evaluate the temperature distribution within a portion of the greenhouse and to investigate the representativeness of single-point measurements for assessing the local microclimate. During the experimental campaign, the vertical and horizontal temperature differences reached maximum values of 9.9 °C and 7.3 °C, respectively. The performed temperature measurements appear to be correlated (R2 > 0.95), and this information was exploited for the prediction of the greenhouse temperature in multiple points, resulting in an average RMSE of 1.3 °C, with differences depending on the specific position taken as reference. These findings offer insights into the representativeness of single-point measurements and the optimal positioning of the sensor station within the greenhouse. The inclusion of microclimate heterogeneity in climate control strategies can help minimise the local presence of unfavourable growth conditions, the excess of energy use, and installation and maintenance costs.
Development of a test rig for the study of gas-based nanofluids
Authors: Milanese Marco , Faraz Muhammad , Colangelo Gianpiero , Risi Arturo de 
Published: December 2024

Abstract
Nanofluids, comprising nanoparticles suspended in conventional heat transfer fluids, reveal significant increase in thermal conductivity and convective heat transfer. This research article investigates the application of gas-based nanofluid in concentrated solar power plant (CSP) technologies. Traditional heat transfer fluids, like synthetic oil and molten salts, present limitations such as flammability, toxicity and operational temperature. In contrast, gas-based nanofluids show improved thermal and optical properties making them a promising alternative for high-temperature solar applications. In this research, an innovative open circuit test bench operating with gas-based nanofluid as heat transfer fluid is presented. Particularly, an open circuit test bench was designed for experimental analysis, incorporating a solar simulator to control sunlight intensity in a laboratory setting. A theoretical model was developed based on solar simulator irradiance, and numerical analysis was conducted. Nanofluids containing CuO nanoparticles exhibited an optimal extinction distance within a few centimeters at a volume concentration of 0.50f. Besides, also the temperature increase achievable with this concentration of nanoparticles is compatible with various thermal and electrical power generation applications.
Effect of combined refrigerant leakage and HEX fouling on performances on an air-to-air EHP in different Italian Climates
Authors: Mastrullo Rita , Mauro Alfonso William , Pelella Francesco , Trinchieri Raniero , Viscito Luca 
Published: December 2024

Abstract
The use of heat pumps for the needs related to the heating and cooling in the building sector has largely increased and it is expected to increase more with the limitations in the use of burners. Even though the use of heat pumps has, generally, a reduced environmental impact, it is important to preserve the performance of the machine during its lifetime to control the direct and indirect environmental impact. In this regard, the effect of some soft faults is relevant, such as refrigerant leakage and heat exchanger fouling, which may contribute to highly degrade system performances, since their evolution often remains unidentified for long periods of time. In particular, it is important to quantify the potential performance degradation that faults may cause on heat pump systems, as well as to identify the most influencing parameters for implementing monitoring strategies.
This work analyzes the effect of these three faults on the behavior of an air-to-air reversible electric heat pump for domestic heating and cooling, both on actual performance and heating/cooling capacity, and of seasonal performance in five different Italian climate conditions of Courmayeur, Milan, Rome, Palermo, Pantelleria. Results show the effect of standalone and combined soft faults on both actual system performance and capacity in heating and cooling operating modes, analyzing counterbalance and superposition effects. Also, the results of lifetime (12 years) performance are presented assuming for each climate condition different scenarios of fault evolution and maintenance strategy.
Steady-state model of Vapour Compression Systems for Refrigeration Applications
Authors: Roberti Giovanni , Giovannini Michael , Molinaroli Luca , Lorenzini Marco 
Published: December 2024

Abstract
This work focuses on the model of steady-state vapour compression systems (VCSs), to provide a useful and simple tool to evaluate their performance, both during the design and tuning phase, but also for the control strategy definition and automatic fault detection applications. The main issue faced in the modelling of such systems is related to the dependence of the thermophysical properties of the fluids on the local temperature conditions, which in turn determines a dependence of the transport coefficients which must be solved iteratively. In this work, a solution algorithm for the non-linear system of equations that describes the system behaviour is developed. The model is validated through experimental data obtained for an experimental refrigeration loop employing a zeotropic mixture, R450A. Comparison of the experimental and computed data of pressure, temperature and mass flowrate is demonstrated to be quite satisfactory.
Energy Balance of a Renewable Energy Community Using Stochastic Methods, a Case Study in Genoa City
Authors: Bocanegra Johan Augusto , Pallavidino Emanuela , Schenone Corrado 
Published: December 2024

Abstract
Renewable energy is at the core of decarbonization; some strategies that could impulse a rapid adoption of those energy systems implies the sharing of the produced energy. Renewable Energy Communities are organizations of different stakeholders (citizens, public entities, authorities, companies) that share energy produced in one or more renewable energy implants of some prosumers that participate in this collective. In this paper, we perform some numerical analysis based on a stochastic analysis of energy consumption and production data; this methodology was implemented to study the performance of a community located in Genoa; in this case, study, the focus is on the energy balance and derive an approximative self-consumption factor.
Fast CFD methodology for accurate prediction of wind turbine airfoil polars by means of Generalized k-omega turbulence model
Authors: Mauro Stefano , Caridi Domenico , Lanzafame Rosario , Messina Michele , Brusca Sebastian 
Published: December 2024

Abstract
Design and optimization of wind turbine blades still relies on 1D numerical codes such as the ones based on the Blade Element Momentum Theory (BEM). These simplified models, require accurate aerodynamics polars as input, for a wide range of Reynolds number conditions, in order to provide reliable predictions. Wind tunnel experimental measurements of lift and drag coefficients is very time consuming and expensive therefore the data available in the scientific literature are generally quite limited. Moreover, the data are often related to few limited operative conditions. On the other hand, the increase of computational power as well as the recent progresses of Computational Fluid Dynamics (CFD) in terms of accuracy and calculation speed have led to an ever wider use of CFD tools for the calculation of the airfoil polars. In this context, the authors developed a fast and accurate CFD methodology based on the use of the recently developed Generalized k-omega (GEKO) RANS turbulence model available in the Ansys Fluent solver. The new procedure to generate a suitable computational domain, the spatial discretization methods as well as Fluent solver settings and GEKO model calibration and optimization are described in detail. The methodology was validated on the basis of experimental data of the widely known S809 wind turbine airfoil, at different Reynolds numbers. Despite the use of a steady RANS turbulence modelling, the proposed CFD methodology demonstrated to accurately predict lift and drag coefficients in fully stalled conditions as well. Moreover, thanks to the automation of the entire CFD process, the methodology allowed to obtain full polars in very short times on a small HPC workstation. Thus, the results of the present work may represent an important step ahead to develop accurate databases of aerodynamic polars by means of a fast and easy but at the same time accurate approach.
The Effect of Entropy Waves Features on the Indirect Noise Generation within an Aeronautical High-Pressure Turbine stage
Authors: Pinelli L. , Giannini G. , Marconcini M. , Pacciani R. , Notaristefano A. , Gaetani P. 
Published: December 2024

Abstract
First stages of aeronautical high-pressure turbine are subjected to inlet distortions generated by the combustor systems. Such disturbances, characterized by velocity and temperature fluctuations, are referred to as vorticity and entropy waves and they are convected downstream by the main flow. Such disturbances interact with the turbine stages affecting the stage efficiency, heat exchange and generating noise emissions. This work summarizes a comprehensive numerical campaign on the effect of different Entropy Waves features (i.e. radial position, clocking and swirl direction) on the indirect noise generation of engine-representative high pressure turbine stage tested at the Politecnico di Milano LFM (Laboratory of Fluid Dynamics of Turbomachinery). The numerical campaign is based on URANS CFD simulations with time-varying inlet distortions, carried out with the University of Florence in-house TRAF code. A Discrete Fourier Transform (DFT) based post-processing tool has been used to extract the low frequency entropy wave content to assess indirect noise emissions. The extensive validation of the TRAF code in previous campaigns grants the fidelity of the results in terms of aerodynamic and acoustic quantities. The numerical results provide a deeper insight of the effect of entropy waves features on indirect noise generation. The outcome of the results may be used by the designer to better understand the combustor-turbine interaction, also considering the possible introduction of innovative fuels such as hydrogen or Sustainable Aviation Fuel (SAF).
Experimental characterization of a variable-pitch Wells turbine
Authors: Licheri Fabio , Ghisu Tiziano , Cambuli Francesco , Puddu Pierpaolo 
Published: December 2024

Abstract
Wells turbines coupled with systems based on the oscillating water column (OWC) principle represent a convenient solution for sea-wave energy conversion. The possibility to operate under the bi-directional airflow that is established within OWC systems is obtained with a symmetrical blade profile staggered at 90 degrees with respect to the turbine’s axis of rotation, resulting in a highly reliable machine. On the other hand, the limited operating range represents a relevant drawback which can be overcome introducing a variable-pitch control of the rotating blades. This control solution has been only marginally investigated with experiments, due to the complexity of devising a mechanism capable to change the stagger angle of the rotating blades.
In this work, a Wells turbine prototype with variable-pitch blades has been built and preliminary investigations are presented, with the aim of characterizing its aerodynamic behavior for different blade stagger angles. The performance of the turbine have been evaluated under regular-wave conditions, for different blade-pitch angles, in order to obtain the information required to define the pitch laws for the maximization of rotor performance.
An Automated Geometric Analysis and Characterization of an Oil-Lubricated Twin-Screw Compressor for Predictive Modeling
Authors: Giardiello Giovanni , Gimelli Alfredo , Riccio Davide , Zeppa Giuseppe 
Published: December 2024

Abstract
Compressor manufacturing companies are showing a growing interest in the development of validated compressor simulation models capable of predicting the behaviour of the machine if subjected to appropriate modifications. A validated predictive model of the entire compressor is useful for analysing the influence of the variation of some fundamental parameters, such as the variation of volumes or new inlet and outlet sections, on the behaviour of the machine. To create these models, geometric parameters such as the variation in volumes, the variation in inlet and outlet sections and the presence of leakage or blowhole phenomena must be provided as input. The precision of these geometric parameters is of fundamental importance for the correct operation of the model and subsequent design analyses. In this work, the authors analysed the complete geometry of an oil-lubricated twin-screw compressor. In particular, an automated calculation methodology was developed using CAD software capable of defining the characteristic curves of the volumes and areas of the compressor: starting from the geometries of the rotors and the stator case, the fluid volumes delimited at the bottom by the rotors and at the top by the case were defined through a Boolean subtraction operation. Subsequently, the volumes that complete the compression phase together were isolated and, through an automatic kinematic analysis with steps of 5° of rotation, starting from the zero reference (null volumes), the characteristic curves of the volumes and inlet and outlet areas were defined through the use of special virtual sensors. The passage sections of the leakage and blowhole leaks were defined in the same way. Particular attention was paid to the analysis of leakage and blowhole phenomena, the presence of which determines a reverse flow of part of the mass flow rate of air during the compression phase, resulting in a decrease in volumetric efficiency. Knowledge of this data is of fundamental importance for the subsequent creation of the 1D/0D model.
Design improvement of USB charger socket ripple defects
Authors: Zhao Ying , Song Shijie , Hu Jianyu , Yang Rentong , Zhang Hongji 
Published: December 2024

Abstract
USB smart sockets have been widely used in modern society. This product directly converts the AC level of the power grid into a DC low-voltage level, making the charging of electronic and electrical products more convenient and safer. It is worth exploring that during the quality inspection of USB smart sockets, testers often find that the DC output voltage of USB smart sockets has large ripples and poor output voltage stability. In response to this finding, this article aims to analyze the causes and types of ripples in USB smart sockets and design a device that can filter out high-frequency ripples and low-frequency ripples at the same time.
A design of series-parallel switching type electrical cabinet for energy storage system
Authors: Hao Wang , Li Haozhan , Hua Sicong , Xu Jianhong 
Published: December 2024

Abstract
Based on the application requirements of multi-load scenarios in the field of specific energy storage, we propose a design of a series-parallel switching type electrical cabinet through the analysis of the energy storage system. The scheme operates the on-off combination of the bus bar switch inside the electrical cabinet through the electronic control system to adjust the series and parallel configurations of the battery racks inside the energy storage container, thus changing the output voltage, current, and power to meet the electricity needs under different load conditions.
Optical fiber liquefied petroleum gas sensor based on the fluorescence quenching of CdSe quantum dot
Authors: Yu Wenwei , Yang Qiaoyun , Chen Yujing , Li Hongjie , Huang Yantang 
Published: December 2024

Abstract
A flameproof optical fiber liquefied petroleum gas sensor was designed and fabricated. Bare-core CdSe and CdSe@ZnSeS@ZnS@CdZnS were modified with pentafluorobenzoic acid (FBA) and encapsulated in PMMA as fluorescent probes for liquefied petroleum gas, enhancing the quantum dots’ response to liquefied petroleum gas detection. Both materials exhibited significant fluorescence quenching in the presence of liquefied petroleum gas, with the Stern-Volmer plot showing a good linear relationship with the gas. A detection optical path was designed, and the relationship between fluorescence intensity and gas concentration was fitted with an expression with a sensitivity of 0.081 (I0/I100-1), enabling real-time detection of liquefied petroleum gas.