bluuebunny/crossref_metadata_2025_split huggingface dataset:
A steady-state numerical approach for the thermo-structural analysis of a cryogenic piston pump
Authors: Cioni Stefano , Balduzzi Francesco , Romani Luca , Sambri Luca , Marianetti Luca , Ferrara Giovanni 
Published: December 2024

Abstract
The process of liquefaction of gaseous fuels, such as natural gas or hydrogen, is an essential technology that helps reduce transportation costs over long distances. Cryogenic piston pumps play a critical role in these systems, as they compress the fuel up to 700 bar before vaporization and storage in high-pressure vessels. Due to the extreme temperatures and pressures involved, the design of these machines poses a significant challenge from the thermal and structural point of view. This work presents the application of a simplified numerical approach for evaluating the thermally induced stresses and deformations through a de-coupled thermo-structural three-dimensional analysis of a prototype cryogenic piston pump. Thermal simulations of the solid domain are carried out to assess the steady-state temperature distribution of the pump. The heat transfer between the pump and cryogenic liquid is computed using three-dimensional steady-state CFD simulations of the suction and discharge phases. Heat generated by friction during the working cycle of the pump and external natural convection are calculated and imposed as a heat source in the simulations. The steady-state temperature distribution is imposed in a finite-element steady-state three-dimensional structural simulation to evaluate the combined effect of thermal loads induced by the cryogenic temperatures and loads induced by the high working pressures. Results show how the proposed methodology can assist in the design of cryogenic piston pumps by offering valuable insights into the most critical aspects of these machines.
Techno-economic assessment of Green Hydrogen Production for Blending in the Natural Gas Network
Authors: Calabrese Mattia , Ademollo Andrea , Busi Lorenzo , Meazzini Michele , Carcasci Carlo 
Published: December 2024

Abstract
Increased electricity generation from renewable sources is critical for the transition towards a zero-carbon future. While this growth of production presents challenges in grid management due to inadequate storage systems for surplus electricity, solutions such as green hydrogen production offer promising avenues for integration into existing infrastructure. By leveraging surplus renewable electricity to power electrolyzers and inject green hydrogen into natural gas networks, we take a significant step forward in realizing an integrated gas-electric system. This study delves into this concept by conducting a comprehensive techno-economic assessment of a hydrogen production facility. The initial step is to determine the required volume of hydrogen to achieve a 10% concentration within a real natural gas distribution network. This value is such that the gas mixture remains within the Higher Heating Value (HHV), Wobbe Index (WI) ranges defined by Italian legislation. The goal is to optimize component sizing using a genetic algorithm to minimize the Levelized Cost of Hydrogen (LCOH) while meeting criteria for green hydrogen production. In fact, results show that an input from electricity grid is necessary to meet the hydrogen demand while maintaining the techno-economic feasibility of the system. A sizing optimization is therefore performed on photovoltaic, electrolyzer and storage system. Furthermore, the study underscores the critical role of energy policies, particularly green hydrogen incentives, in determining the economic feasibility of the system. By analyzing their impact on economic revenues, the authors emphasize the importance of supportive regulatory frameworks in driving the transition towards a more sustainable future.
Identification of synthetic parameters for the thermal characterization of Phase Change Materials in MH-PCM hydrogen storage systems
Authors: Krastev V. K. , Baldelli M. , Bartolucci L. , Cordiner S. , Falcucci G. , Mulone V. 
Published: December 2024

Abstract
The present work adopts a multidimensional CFD methodology to investigate the thermal coupling between Phase Change Materials coupled and intermetallic Metal Hydrides, for hydrogen storage and delivery. In contrast to the currently available literature on this topic, the focus here is shifted from specific application-oriented modeling towards the systematic identification of a minimum set of parameters to highlight eventual similarity patterns among different PCM families. To achieve this goal, a representative cylindrical-type MH-PCM system model has been defined for a discharge-mode configuration, taking into account engineering-related constraints like the optimal hydrogen pressure delivery and hydrogen massflow control. The results obtained are expected to significantly improve design practices based on standard CFD methods, as well as to pave the way for the derivation of fast and accurate data-driven model surrogates for real-time modeling applications.
Enhancing PEM Electrolyzer Performance through Electrochemical Impedance Spectroscopy: A Review
Authors: Discepoli Gabriele , Barbi Silvia , Venturelli Matteo , Montorsi Monia , Montorsi Luca , Milani Massimo 
Published: December 2024

Abstract
The development of electrolyser technology is currently undergoing a breakthrough phase, poised to meet the upcoming demands for widespread hydrogen production under stringent requirements including high efficiency, purity, affordability, and rapid response to harness the full potential of renewable energy sources. In recent years, this rapid advancement necessitated concerted efforts supported by various diagnostic tools to achieve a comprehensive understanding of the underlying mechanisms governing electrolytic processes across diverse operating conditions. These tools prove particularly effective when capable of providing real-time insights into the features and behaviour of the studied system during operation. This paper presents a review of the latest diagnostic tools employed in the investigation of modern electrolyzers, with particular emphasis on electrochemical impedance analysis (EIS). It delves into how this tool facilitates a deeper comprehension of the fundamental electrochemical principles governing electrolysis, its evolution in the study of electrolysis, and its interconnectedness with other diagnostic methodologies.
Hydrogen as a direct heat exchange fluid in room temperature hydride systems: Numerical study on the desorption process
Authors: Vincenti Ferdinando , Valenti Gianluca 
Published: December 2024

Abstract
Hydrogen, as an energy carrier, is a promising candidate to foster decarbonization. However, its storage poses significant challenges. Common methods, such as compressed gas and liquid hydrogen, have high energy consumption and safety concerns. Recently, solid hydrogen storage in materials like metal hydrides has gained attention for their ability to store hydrogen safely at low pressures and low temperatures. This study aims to develop a numerical model to simulate the performance of metal hydrides using hydrogen as a direct fluid heat exchanger during desorption. The model, formulated as a system of partial differential equations, is implemented in MATLAB with the ODE15s solver and applied to a disk-type lanthanum nickel reactor to minimize pressure drops. Performance is investigated by varying design parameters, including reactor length and diameter, bed porosity, hydride particle diameter, operating pressure and temperature, and hydrogen mass flow rate at the reactor inlet. Additionally, the energy consumption of auxiliary equipment, such as pumping and thermal power, is evaluated. Results show that the system energy requirement is about 8-9% of the hydrogen lower heating value, with most desorption occurring in less than 300 seconds. The reactor dimensions are crucial for fast desorption and low pressure drops, with pumping power under 1 W given the small thickness and flow rate. Particle diameter and porosity have minor impacts, while pressure, temperature, and flow rate are fundamental. High temperatures, low pressures, and high recirculating flow rates favor the reaction, though a trade-off between performance and energy consumption is necessary since all high temperatures high recirculated mass flow rate allows for high consumption.
Investigating experimentally the performances of a natural gas reciprocating compressor adapted to pure hydrogen up to 30 MPa
Authors: Dalberto T. , Battistella F. , Perus T. , Corsini M. , Ravidà A. , Valenti G. 
Published: December 2024

Abstract
Hydrogen as an energy carrier can be integrated into various value chains, enabling the decarbonization of hard-to-abate processes. Hydrogen storage is necessary to handle the intermittency of renewables. Moreover, it allows hydrogen to be deployed in sectors such as mobility and backup power. Currently, high-pressure vessels are typically used for hydrogen storage. The compression process is required since hydrogen production occurs at lower pressure than storage. This study examines a three-stage reciprocating compressor for natural gas, which is operated with pure hydrogen. The compressor, driven by a 3-kW electric motor, can deliver 30 MPa starting from pressures between 0.3 and 0.8 MPa. The aim is to assess the energy impact of compression on hydrogen production and analyze potential issues such as leakages or contamination that can arise after changing the Gluid. The study involves measuring hydrogen Glow rates, inlet and outlet pressures, and electric power consumption during the Gilling of a vessel. The experiment shows a specific power input of 1.2 kW/(Nm3/h), more than 1/3 of the lower heating value, maximum isothermal efficiency of 21% and maximum isentropic efficiency of 34%. The optimal compression ratio is found to be between 25 and 30. Based on the few data available in literature, the performances do not reach state-of-art levels of 55-80% isentropic efficiency. However, the device was optimized for the compression of natural gas, and the scope of this study was to use it with fewer possible modifications.
Impact of Hydrogen Blending Policies on the Energy Efficiency, Environmental and Economics parameters of Residential Gas Boilers
Authors: Vespasiano Domiziana , Vespasiano Flavia , Massulli Axel Riccardo , Ciancio Alessandro , Santoli Livio de 
Published: December 2024

Abstract
At present, gas-fired boilers are among the most common systems for heating residential buildings. The potential integration of hydrogen into the gas network is being considered as a viable option for decarbonising heating systems. This study investigates the impact of hydrogen injection into the network, focusing on how it affects boiler performance by analysing energy and environmental parameters with different hydrogen fractions. Specifically, the study examines the technical, economic and environmental consequences of using hydrogen-enriched natural gas (H2NG) blends in gas-fired boilers. Primary energy consumption and emissions were evaluated using H2NG blends with hydrogen fractions ranging from 0% to 25% by volume. In addition, the study evaluates the influence of the blend on the system operating costs and the LCOH (levelized cost of heat) in relation to the LCOH2
(levelized cost of hydrogen). An analysis was carried out to determine the effect of hydrogen on emissions to facilitate the calculation of the Carbon Abatement Cost (CAC) of using the blend. The results show that the incorporation of H2NG blends further reduces the EPnr, with a 30% hydrogen blend achieving a 12.05% reduction. CO2 emissions also decrease proportionally with increasing hydrogen content. Economically, LCOH increases with increasing hydrogen content, with a 30% blend increasing boiler costs by 4.93%. In conclusion, the integration of hydrogen into heating systems can significantly reduce both non-renewable energy consumption and CO2 emissions but requires an increase in costs for fuel purchase due to the different energy vector.
Simultaneous estimation of in- and out-of-plane thermal conductivities of composite materials using a contact-heating technique: an optimum experimental set-up design
Authors: D’Alessandro Giampaolo , Monte Filippo de , Sfarra Stefano 
Published: December 2024

Abstract
The optimum set-up of a two-dimensional (2D), transient, three-layer, heat conduction experiment aimed at simultaneously estimating the thermal properties of composite materials is designed. The experimental apparatus is based on the plane-source method consisting of a thin electrical heater in contact with two larger samples of the same material and thickness.
Due to the thermal symmetry of the apparatus and neglecting the thermal heater inertia and related contact resistance with the sample, the three-layer composite conduction problem is modeled through only one orthotropic rectangular plate (sample) whose thermal properties are assumed temperature-independent. This plate is partially heated for a finite period at the front boundary through a surface heat flux (due to the thin heater), whereas its opposite boundary is subject to heat losses with the environment simulated by a heat transfer coefficient (the remaining boundaries are kept insulated). This coefficient accounts only for free convection when the unheated back side of the sample is exposed to the surrounding air and, hence, its temperature is measured using an infrared camera or a pyrometer. However, if thermocouples are used on the back side of the sample, it is a common practice to thermally insulate it to reduce the air disturbance on the thermal measurements. In this case, the above coefficient accounts for both the insulating material and free convection with the air.
The exact analytical temperature solution of the addressed heat conduction problem is obtained using a generalized solution available in the specialized literature. The superposition principle is also applied to account for a finite heating period. Then, the scaled sensitivity coefficients of temperature with respect to the parameters of interest (in- and out-of-plane thermal conductivities, volumetric heat capacity, and the heat transfer coefficient with the surrounding ambient) are computed on the back side of the specimen, and a sensitivity analysis is performed to establish whether correlation between them exists at different locations. Finally, the optimum experiment is designed by applying one of the D-optimum criteria, known as Δ+ criterion. Its application leads to the optimum heating and experiment times, the optimum sample aspect ratio, and the optimum width of the heated region.
Thermal Transport in the Entry Region of a Microchannel in the Presence of Electro-osmotic Flow
Authors: Suzzi Nicola , Lorenzini Marco 
Published: December 2024

Abstract
The motion of a polar fluid in microducts induced by an external electric field, known as electro-osmotic flow, enables fluid circulation without the need for mechanical devices. This feature makes it particularly appealing for the thermal management of electronic components, as microchannels with almost any cross-sectional shape can be easily integrated on the chips. Therefore, it is essential to evaluate how the channel’s geometry influences heat transfer performance. This study investigates the thermal entry region and fully developed electro-osmotic flow in a microchannel with a rectangular cross-section and smoothed corners, with one adiabatic wall and uniform temperature elsewhere. The paper proposes correlations for the Poiseuille and Nusselt numbers, taking into account the aspect ratio and non-dimensional smoothing radius under fully developed thermal and hydrodynamic conditions, which can be valuable for practical design purposes. The study also emphasizes how Joule heating may lead to the reversal of heat flow and how the thermal entry length is linearly dependent on the logarithm of the non-dimensional Joule heating in thermally developing flow. Additionally, it demonstrates that smoothing the corners may increase the local Nusselt number over sharp corners, but it may also shorten the thermal entry length.
Surface Roughness Effects on Heat Transfer in Additive Manufactured Microchannels: A CFD Study
Authors: Gammaidoni Tamara , Zembi Jacopo , Battistoni Michele 
Published: December 2024

Abstract
Microchannel heat exchangers are widely used in applications where compactness and efficient heat transfer are essential. The difficulty of producing metal microchannels with conventional techniques leads to the adoption of additive manufacturing, such as Direct Metal Laser Sintering (DMLS), which offers unprecedented design freedom but introduces relevant surface roughness, impacting heat transfer phenomena.
The objective of this research is to methodically examine the impact of roughness factors on heat transfer through Computational Fluid Dynamics (CFD) analyses.
In particular, the parametric study focuses on one specific spatial parameter, the roughness Correlation Length (CL), to consider the spatial distribution of surface features. This parameter offers a more thorough analysis than the commonly used Average Roughness (Ra
) and Root Mean Square Roughness (Rq
). Specifically, two types of rough surfaces are investigated: isotropic and anisotropic, to capture the complex interplay between surface roughness and heat transfer more accurately.
This research advances understanding regarding the effects of surface roughness on heat transfer, advocating for the adoption of comprehensive spatial parameters for its accurate characterization. Additionally, the findings provide crucial insights for optimizing thermal management systems, guiding engineers in improving heat transfer efficiency in additively manufactured microchannels.
On the influence of the refrigerant inlet position and circuitry layout on plate-finned tube evaporator performance through the hybrid method
Authors: Macchitella Silvia , Colangelo Gianpiero , Starace Giuseppe 
Published: December 2024

Abstract
Multiple factors can impact the performance of a plate-finned tube evaporator in terms of heat transfer rate and refrigerant pressure drops, including the circuitry layout and the position of the refrigerant distributors. In order to assist designers, various circuitry layout alternatives together with different refrigerant inlet positions were examined in this work, using the hybrid method to calculate the evaporator performance. Based on prediction functions coming from the outcomes of either numerical, analytical, or experimental analysis, the hybrid method has the advantage of combining affordable computing costs with accurate findings. Moreover, the refrigerant inlet position can cause uneven vapor quality entering the various circuits. This characteristic, along with the variation in flow rates it implies, was also examined to investigate their influence on the heat exchanger’s performance.
The biomethane potential for public transport decarbonization in Italian cities
Authors: Noussan Michel , Prussi Matteo , Chiaramonti David 
Published: December 2024

Abstract
The transport sector remains heavily reliant on oil products, and it is among those that are considered harder to decarbonize, especially in some specific segments. Considering public transport, there is currently a significant interest in electrifying urban buses, especially for some routes that are well suited for the current characteristics of battery electric buses. However, for some applications, including long-distance buses, biomethane could play an important role in contributing to the decarbonisation of the sector, especially considering the important part of the current fleet in Italy that is already operating on fossil natural gas. This analysis presents a comparison of the potential role of biomethane to support public transport decarbonization in Italy, by estimating CO2 equivalent emissions savings considering the current biogas plants and natural gas buses in Italian cities. An additional evaluation is performed considering the future expected evolution of biomethane production in line with the new Piano Nazionale Integrato per l’Energia e il Clima, that aims to a total production of 5.7 bcm by 2030, as well as the expected 1.5 bcm of biomethane allocated to the transport sector. Within these maximum potential levels, the results of the analysis demonstrate the important savings that can be achieved with biomethane, especially when exploiting specific feedstocks that have a very low impact in terms of well-to-wheels emissions. Biomethane can represent an interesting complement to electric buses, as it can exploit the already existing fleet based on natural gas, and it also shows a number of advantages on routes that are not suitable for electric buses.
Definition and Validation of a Zero-Dimensional IC Engine Model for Assessing the Performance of Different Methane-Hydrogen Mixtures
Authors: Cazzoli Giulio , Falfari Stefania , Bianchi Gian Marco 
Published: December 2024

Abstract
To decarbonize the maritime transport sector, a solution inspired by the automotive industry involves using a solid oxide fuel cell (SOFC) in conjunction with an internal combustion engine. For optimal emission efficiency, the internal combustion engine is fueled with a primary fuel, typically methane already on board for feeding the SOFC, plus anode off-gases from SOFC, which are a mixture of variable composition of hydrogen, carbon dioxide, and carbon monoxide. To assess the performance of the integrated system (SOFC+ICE) and subsequently search for an optimal set-up, it is useful to use a zero-dimensional model of each component of the system. Particularly, the internal combustion engine model must balance speed of execution with flexibility in terms of fuel composition, engine dimensions, and other relevant parameters. In this study, an engine model originally developed for gasoline-fueled ICE, is adapted for variable methane-hydrogen mixtures. The model is validated against experimental data measured on an engine operating with similar mixture compositions and available in the literature.