bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy analysis of a hybrid electro-hydraulic system for efficient mobile hydraulics
Authors: Padovani D , Rundo M , Fresia P , Altare G
Published: December 2023

Energy efficiency plays a significant role in mobile hydraulics due to the high amount of carbon dioxide and pollutants being released into the atmosphere. Efficiency improvements are urgently needed, so the electrification of mobile hydraulics represents a fantastic opportunity in this regard. This approach leads to electro-hydraulic systems that remove functional flow throttling in control valves and enable energy recovery. Fuels savings were already demonstrated in simulation, but the literature does not offer entire energy analyses of these electro-hydraulic solutions. This limitation prevents complete system-level comprehension and does not give enough insight to pinpoint areas for further efficiency improvements. Thus, this paper focuses on a hybrid system for excavators based on electro-hydraulic drives that is compared against the original valve-controlled layout. The objective is to quantify the energy flows insight the excavator during relevant operations and highlight the resulting energy losses. The outcomes confirm that electro-hydraulic solutions are suitable for a low-carbon economy. They indicate hydraulic actuators, speed-controlled pumps, and electric motors as the critical components for further energy efficiency enhancement excluding the combustion engine.
Design considerations about the hydromechanical transmission IC2OC
Authors: Rossetti A , Andretta N , Macor A
Published: December 2023

The hydromechanical transmission IC2OC operates as an Input Coupled transmission at low speeds and as an Output Coupled transmission at high speeds; a series of clutches allows the shift between two layouts. In this way the transmission speed range can be almost doubled.

The design of this transmission requires the full mechanical speed value for both basic layouts. Since these values heavily influence transmission performance, their choice must be made carefully.

In this paper two choice criteria for these two speeds are proposed and discussed: the first one refers to the optimal choice for each basic layout; the second sets these speeds in correspondence with the speed of the maximum energy processed in a working cycle.

The effectiveness of these two criteria, applied to an off-road vehicle transmission, demonstrates that the former guarantees greater efficiency than the latter, despite its good assumptions.
Energy analysis of a hydrogen integrated system in the residential sector
Authors: Mennilli Francesca , Jin Lingkang , Rossi Mosè , Mugnini Alice , Comodi Gabriele
Published: December 2023

Nowadays, buildings are responsible for almost 40% of global energy consumption, which is addressed by thermal (e.g., heating, cooling, and hot water) and electric (e.g., lighting and household appliances) loads. To meet the residential energy demand and, at the same time, ensure the decarbonisation of the energy infrastructure, hydrogen-based cogeneration systems might represent a viable solution. This work aims at evaluating the performance of a green hydrogen integrated system consisting of a Proton Exchange Membrane (PEM) electrolyser, hydrogen storage tanks, and a PEM fuel cell to meet both the electricity and, partially, the thermal energy demands of a condominium located in the center of Italy. The analysis considers a single energy scenario in which a Photovoltaic (PV) plant installed on the roof is directly connected with the hydrogen integrated system without any withdrawal from the national grid (e.g., off-grid operation mode). Results showed that, during the year, the user is completely self-sufficient from the electricity demand point of view. Furthermore, 22% of the thermal need can be satisfied through the fuel cell cogeneration system.
Comparison between optimal refueling infrastructures for zero emission waste transportation vehicles in Valle Camonica
Authors: Vincenti Ferdinando , Bontempi Manuel , Poetini Bruno , Furlanetto Dario , Valenti Gianluca
Published: December 2023

The aim of this work is to conduct a comprehensive and fair comparison between fleets of vehicles powered by different technologies, namely electricity, compressed hydrogen, and liquid hydrogen. The study followed a well-defined methodology, starting with the development of a mixed-integer linear programming (MILP) model using MATLAB and the YALMIP toolbox. The primary objective of the model is to minimize the total annual cost associated with the infrastructure required for refuelling the fleet of zero-emission vehicles. The battery electric vehicle refuelling infrastructure is used as a benchmark, with a total annual cost of around 200000 €/y. The compressed hydrogen and liquid hydrogen infrastructure are comprehensive of a solar photovoltaic field. The hydrogen refuelling facility are analysed varying the price of the electricity. In the most profitable configuration, the compressed hydrogen refuelling facility cost around 320000 €/y and for the liquid hydrogen 480000 €/y. The sensitivity analysis, performed varying the cost of electricity, shows that it is never convenient to use hydrogen vehicles even in condition of high electricity prices. When it is possible to use electric vehicles and there are no constraints related to payload, range or refueling logistics they must be employed, as they are the most cost-effective solution to cancel the vehicles emissions.
Hydrogen production by water photo-sonolysis: a modal approach to enhance the ultrasonic acoustic field in the solution
Authors: Domenighini P. , Gambelli A.M. , Rossi F , Cotana F.
Published: December 2023

Water photo-sonolysis is considered one of the most innovative ways of hydrogen production. Cited by the Italian strategy on hydrogen research as a promising field for innovation research, it consists of the coupling work of solar-light electromagnetic waves and mechanical ultrasonic waves to induce water splitting. Water photolysis requires catalysts to be performed and optimized, whereas ultrasound sonolysis acts independently. In the state of the art, it was experimentally demonstrated that the rates of hydrogen production by sonolysis rise according to resonance peaks of the solution in function of ultrasound wavelength. To enhance the effects of the ultrasound, the resonance of the solution can be geometrically achieved by acoustic modal analysis of a set of possible solution volumes. According to the geometry of the photo-sono reactor at the lab scale, the shape of the tested solution volumes is cylindrical. The modal analysis was led in a Matlab environment considering the cylindrical volume’s geometry and the fluid’s physical properties. To check the reliability of the simulated results, pressure measurements were led at the lab scale on the simulated water volumes by means of a hydrophone at a significant number of points.
Multi-physics model development and application to real-case alkaline electrolyzer
Authors: Dreoni M , Balduzzi F , Ferro F M , Fagioli G , Panichi K , Ferrara G , Bianchini A
Published: December 2023

The realization of mathematical, multi-physics models for alkaline electrolyzers is crucial for advancing this technology. Lumped parameter models offer shorter simulation times, compared with other approaches, and practical industrial applications. If electrochemical models provide the polarization curve, the hydrogen production rate, and the device efficiency, thermal models solve the equations involving the electrolyte temperature. With a coupled approach, the two models can be linked together by considering the device voltage as temperature dependent. Despite the relevance of such models, few instances of their direct application on existing electrolyzers can be found in the literature, and combined electrochemical-thermal simulations are rare.

This study presents a multi-physics model applied on an alkaline electrolyzer and validated against measurements acquired on a dedicated experimental test bench.

The physics-based model accurately predicts the polarization curve, exhibiting a high precision match with experimental data. Additionally, it identifies material or geometrical imperfections in the electrolyzer, allowing for optimization in the design phase. The thermal model successfully converges to the desired electrolyte temperature of 72 °C under stationary conditions. Additional transient simulations demonstrate an average deviation of only 0.25% compared to the measured temperature trend. Finally, a sensitivity analysis explores the coupling of the electrolyzer with a wind turbine under different wind conditions.

The study showcases the effectiveness of the coupled electrochemical-thermal model in predicting electrolyzer performance, with a direct application to a wind turbine power output.
Experimental methodology for the characterization of a hydrogen-fuelled Pressure Gain Combustor
Authors: Tempesti C , Romani L , Ciampolini M , Hakuri O , Ciccateri F , Ferrara G
Published: December 2023

Gas turbines have been a key technology in many industrial sectors for over 50 years and they will continue to play a crucial role in the energetic scenario. Nevertheless, these systems are approaching their efficiency limits and performance improvements are becoming increasingly difficult to achieve. In this context, Pressure Gain Combustion (PGC) has emerged as a promising technology: replacing the isobaric combustion with a quasi-isochoric process creates a rise in total pressure across the combustion chamber, enhancing their potential performances. However, it is a complex process influenced by combustion chemistry, heat transfer, and fluid dynamics, and its unsteadiness increases the complexity of measurement campaigns. Thus, several challenges still need to be addressed for its development.

This paper shows the experimental methodology followed to characterize an innovative deflagrative-based PGC fuelled with 100% hydrogen. Dynamic pressure sensors were installed inside, upstream, and downstream of the combustion chamber and acquired at a high frequency (1 MHz) to describe in detail the process.

Downstream the combustor, an orifice simulated the pressure drop across the turbine. Different fuel pressure has been tested, varying the operating parameters and the position of the pressure sensors inside the chamber. For each configuration, a detailed analysis of the mean pressure trends and cycle-to-cycle variation was carried out and will help optimize the system in the following tasks of the project. The experimental methodology described can be used to better investigate the physics of Pressure Gain Combustors and allow complete exploitation of their potentiality in terms of work extracted, resource consumption, and pollutant emission.
Fuel Cell Hybrid Electric Vehicles: Fuel Cell experimental characterization and modeling towards the development of a Hardware-in-the-Loop platform for advanced powertrain design
Authors: Bartolucci Lorenzo , Cennamo Edoardo , Cordiner Stefano , Donnini Marco , Grattarola Federico , Mulone Vincenzo , Pasqualini Ferdinando
Published: December 2023

Greenhouse gas emissions in transport sector is a critical issue, with automobiles and trucks responsible for emitting nearly 5.9Gt of CO2. Addressing climate change is then of paramount importance to avoid irreversible consequences. Advanced technologies are being developed to achieve this goal. Among them, Fuel Cell Hybrid Electric Vehicles (FCHEVs) offer several benefits, including wide applicability and range, short refueling times, and no tailpipe emissions, that can only be exploited if optimizing their design. This requires time and cost-consuming iterative processes, and Digital Twins (DTs) and Hardware-in-the-Loop (HIL) test benches are then gaining importance with respect to prototype manufacturing. In this study, the basis for a HIL application is posed, including a 2kW Fuel Cell (FC) and a bidirectional DC power supply used to emulate the electric motor. After characterizing the FC, DTs have been calibrated and validated through experimental tests; DTs have then been included into a FCHEV microcar model and its performances have been analyzed. Results have shown high accuracy in representing the real FC performance, with a 5% maximum error from the energy standpoint. Moreover, HIL approach has been proved to be fundamental for catching peculiar transient phenomena, significantly impacting on the powertrain design and performance.
Hydrogen volumetric fraction effects on HCNG refuelling station CAPEX
Authors: Sgaramella Antonio , Ciancio Alessandro , Mojtahed Ali
Published: December 2023

Greening the transport sector is crucial for the achievement of the ambitious decarbonisation goals set by the Conference of the Parties (COP21) Paris agreement to keep global warming “well below 2 degrees Celsius above preindustrial levels, and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius”. Battery electric vehicles and hydrogen fuel cell electric vehicles will play a key role in the reduction of greenhouse gas emissions in the road mobility. Nonetheless, those technologies still need to face some technological challenges. Hence, hydrogen enriched natural gas (HCNG) can play an important role as bridging technology. This study envisages the upgrade of an existing compressed natural gas (CNG) refuelling station (RS) in HCNG-RS. Particularly, an analysis regarding the impact of different hydrogen volumetric fractions in the blend on the total CAPEX of the HCNG refuelling station is carried out, by evaluating the HCNG fill-up demands for a proper refuelling station sizing. The proposed HCNG refuelling station layout foresee the on-site hydrogen production by means of an electrolyser fed by PV energy. Each component of the station has been adequately sized based on the resulting peak HCNG refuelling demand. The highest CAPEX value is recorded for the 30%vol. HCNG, amounting up to 3.52 M€.
A potential coupling of reforming and electrolysis for producing renewable hydrogen from landfill gas
Authors: Massulli Axel Riccardo , Mojtahed Ali
Published: December 2023

Organic sold waste disposed of in landfills undergoes a mostly anaerobic process which generates a mixture of methane (CH4), carbon dioxide (CO2) and other various gases such as nitrogen, oxygen, sulphides, and non-methane organic compounds (NMOC), known as landfill gas (LFG). Being composed mostly of CH4 and CO2, landfill gas is a potent greenhouse gas (GHG). As a result, various waste treatment interventions are required to minimize the potential catastrophic damage to the environment from direct greenhouse gas emissions from landfills. One effective solution is combustion to generate electricity exploiting methane’s flammability properties. Biomass-based power plants have been present for decades. However, the combustion process is accompanied by a remarkable production of thermal energy which is typically not exploited and therefore lost to the ambient. The current work presents an energetic solution to manage organic waste by employing green hydrogen production. To do so, a hybrid layout based on a cogeneration unit (CHP) fed with landfill gas is considered. The electrical power produced by the CHP is used to produce hydrogen through low-temperature water electrolysis. Furthermore, due to the significant waste heat available in the system, excess thermal power is employed for the methane steam reforming process through a heat recovery section. Hydrogen produced from the reforming section is green since the input is from landfill gas, which is considered renewable. The levelized cost of hydrogen produced from such a hybrid layout is obtained and compared with non-renewable sources in this field. In addition, the annual H2 production rate is calculated for a capacity factor equal to 70%. The results show an annual Hydrogen production of about 167 t/y. LCOH at the stack of about 2 €/kg is reported.
Decarbonization of methanol production - Techno-economic analysis of Power-to-Fuel process in a Hydrogen Valley
Authors: Ciancio Alessandro , Mojtahed Ali , Sgaramella Antonio
Published: December 2023

The European Union set the decarbonization goals and green hydrogen can play a crucial role for the greenhouse gas emission reduction. Hydrogen Valleys can be pivotal for the hydrogen economy, by integrating the local green hydrogen (H2) production into the industrial sector. Thus, by means of the Power-to-Fuel approach H2 can be exploited for the synthetic fuel. This study aims at investigating the synthetic methanol (CH3OH) production process with recycled carbon dioxide (CO2) and green hydrogen in a Hydrogen Valley. Currently, industrial-scale methanol is produced from natural gas, where methane (CH4) reacts with H2O at high temperature and pressure. The green hydrogen can improve the long-term sustainability of this process, making the green methanol exploitable in the hard-to-abate sectors. Therefore, the purpose of this research is to evaluate a techno-economic analysis of various scenarios for the synthetic methanol production process in the Hydrogen Valley. This analysis has been carried out for different time periods: 2020, 2030, and 2050. The outcomes show that the current Levelized Cost of Methanol production ranges between 158.41 €/MWh and 227.69 €/MWh. In the long term, those values decrease to a range of 72.01 €/MWh to 97.05 €/MWh. The most suitable RES capacity scenarios have been derived along with the associated global investment costs. The best scenario in the short and medium term envisages 1 MW of on-shore wind plants and 1.5 MW of photovoltaic plants with a total investment cost of 4.10 M€ by 2020. In the long term, the best scenario foresees 2 MW of photovoltaic and 0.5 MW of on-shore wind. In so doing the 2050 investment cost is reduced to 1.62 M€.
CFD-3D and 1D modeling of fuel cell powertrain for a hydrogen vehicle
Authors: Marra Carmine , Corda Giuseppe , d’Adamo Alessandro
Published: December 2023

As it is known the transport sector represents a major contributor to climate change. In particular, private transport contributes to the degradation of the air quality inside the cities or the residential areas. To address this issue, a progressive reduction of the use of fossil fuels as a primary energy source for these vehicles and the promotion of cleaner powertrain alternatives is in order. This study focuses on designing a fuel cell powertrain for a hydrogen-powered passenger car using numerical modeling. To this purpose, we initially modeled a base fuel cell and optimized its performance by using various materials for the bipolar plates and adjusting the platinum loading between the anode and cathode. Then, a preliminary design of the new powertrain has been proposed in order to achieve a nominal power of 100 kW and it has been tested on a WLTP 3b homologation cycle. Finally, we have been able to numerically estimate the behavior of the three main feeding line: hydrogen line, air line and cooling line. In conclusion, the obtained results demonstrate how numerical modelling can be successfully used in the design of complex systems such as those related to alternative energy. This work also provides a solid basis for the future development of increasingly efficient and environmentally friendly hydrogen vehicles.
Utilisation of Ethyl Levulinate as Diesel Fuel Additive
Authors: Frigo S , Antonelli M , Francesconi M , Galletti AM Raspolli
Published: December 2023

The world is going through a radical phase of energy conversion, due to both environmental and socio-economic factors, which will lead to a progressive transition from fossil to renewable energy sources. As regards the light land transport sector (cars), the abandonment of propulsion systems based on the use of internal combustion engines (ICEs) in favour of electrification seems the preferred solution. On the contrary, for heavy land (trucks and trains), marine and air transport sectors the path to follow is not yet clear.

A possible alternative to fossil fuels is certainly represented by bio-fuels, which should allow a drastic reduction of CO2 emissions and, to a lesser extent, of CO and particulate matter. The use of bio-fuels does not involve a drastic change in the systems of distribution and use of energy, as the existing infrastructures can remain unchanged. In particular, second generation bio-fuels (obtained from non-food matrices) are attracting more and more attention and, among these ones, oxygenated alcohols obtained from residual lignocellulosic biomasses appear extremely promising for the use in diesel engine.

The present study analyses the utilisation of ethyl levulinate (EL), a versatile second generation bio-fuel that can be used in Diesel/gasoline engines. EL can be conveniently obtained from the sustainable one-pot acid-catalyzed conversion of waste lignocellulosic feedstocks, employing bioethanol as the solvent/reagent.

EL has been tested in a small DI Diesel engine, blended up to 25% by volume with a commercial Diesel fuel, without significative changes in engine performance, moderately increasing NOx and HC emissions but significantly lowering soot and CO emissions by more than 50%.
Characterization of Hydrotreated Vegetable Oil (HVO) in a Euro 6 Diesel Engine as a Drop-In Fuel and With a Dedicated Calibration
Authors: d’Ambrosio S , Mancarella A , Marello O
Published: December 2023

Renewable fuels can play an important role in achieving future goals of energy sustainability and CO2 reduction. In particular, hydrotreated vegetable oil (HVO) represents one of the most promising alternatives to petroleum-derived diesel fuels. Several studies have shown that conventional diesel engines can run on 100% HVO without significant modifications to the hardware and control strategies. The current activity has experimentally evaluated the potential of HVO as a “drop-in” fuel, i.e., without changes to the original baseline calibration, comparing it to conventional diesel fuel on a 2.3-litre Euro 6 compression ignition engine.

Tests revealed that HVO can significantly reduce engine-out soot (by more than 60%), HC and CO emissions (by about 40%), compared to diesel, while NOx levels and fuel conversion efficiency remain relatively unchanged under steady-state warmed-up conditions. The advantages of HVO proved to be further enhanced when the engine has not yet warmed up.

Using statistical techniques of design of experiments (DoE) at three warmed-up steady-state operating points, the main engine control parameters were recalibrated to demonstrate that engine-out emissions can be further optimized with a dedicated calibration.
Analysis of the Vibrational Behavior of dual-fuel RCCI combustion in a Heavy-Duty Compression Ignited Engine fueled with Diesel-NG at Low Load
Authors: Silvagni Giacomo , Moro Davide , Ravaglioli Vittorio , Ponti Fabrizio , Corti Enrico , Brusa Alessandro , Cavina Nicoló , Narayanan Abhinandhan , Srinivasan Kalyan K. , Krishnan Sundar R.
Published: December 2023

In the field of internal combustion engines, the Low Temperature Combustions (LTC) appear to have the potential to reduce the formation of both soot and nitrogen oxides. One of the most promising LTC is Reactivity Controlled Compression Ignition (RCCI) which is based on the combustion of a lean low reactivity fuel-air mixture generated in the intake manifold and autoignited by small injections of high reactivity fuel introduced at high pressure in the combustion chamber. By the combination of net-zero natural gas and biodiesel, such LTC methodology might represent a suitable solution moving toward zero-emissions in transportation sector.

Despite the potential to reduce pollutant emissions, Low Temperature Combustion strategies face a challenge in controlling the angular position where the combustion takes place which can be overcome by a proper management of the high-pressure injections.

One potentially interesting application is related to trucks, mainly because they have long periods of idling, since emissions can be drastically reduced by means LTC. A single cylinder research engine for heavy duty application is operated under steady state conditions at low load and speed to analyze the possibility of controlling the engine behavior in dual fuel RCCI mode. The results indicate that the combustion mode switches from the dual-stage to gaussian within a narrow angular range. A further advance of the start of injection can generate misfires and significant variations in typical combustion indexes, while a delayed start of injection can cause impulsive combustion that rises the cylinder temperature and results in high-frequency pressure oscillations inside the combustion chamber. These oscillations are related to the combustion chamber typical resonance frequency, and if relevant in amplitude and persist for a long time, they might generate a potential source of failures.
Theoretical and experimental evaluation of electric coolant pump benefits in real driving cycles
Authors: Marco Di Bartolomeo , Davide Di Battista , Roberto Cipollone
Published: December 2023

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

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

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

Even if the first examples of free associations of citizens for the exploitation of local energy resources date back to the end of the nineteenth century, it is with the EU Directive 2018/2001 RED II that the concept of Renewable Energy Community is introduced for the first time. It is an association of ordinary citizens, commercial activities, public administrations, small and medium-sized enterprises, aimed at the production and maximization of the use of energy produced on site. Alongside the social (greater energy independence, awareness of environmental issues) and environmental (promotion of renewable energy and reduction of CO2 emissions) aspects, the economic one is equally relevant in order to contribute to the dissemination of RES, maximizing its self-consumed share in the production site and therefore reducing the loads of overproduction on the transmission network.

In this paper, the authors analyze in detail the regulatory aspects and the technological solutions that are contributing to the diffusion of these communities at national level, also in the light of the recent ARERA Resolution for widespread self-consumption. The critical issues associated with their implementation in disadvantaged area in terms of population density will be discussed. The case study of the Municipality of Osidda in Sardinia will be presented, where the provision of social services and the achievement of energy independence represent the tools to combat the rapid depopulation suffered in recent years. The model developed by the authors starts from an initial careful collection of data, aimed at overcoming the problems of measuring and estimating the energy consumption of very different users (residential and public), identifying the possible solutions able to maximize the shared energy produced by RES, inside the RECs and consequently the economic return connected to national economic incentives.
Ammonia heat pumps for district heating: thermo-economic optimization analysis based on evaporator geometry for either direct expansion or chilled water configurations
Authors: Passarelli A F , Viscito L , Merlo U , Filippini S , Mauro A W
Published: December 2023

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

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

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

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

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

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

In the seismic data processing, high energy surface wave overlaps with effective wave, which affects the quality of seismic data imaging. The traditional frequency domain method can effectively remove surface wave, but it will damage the low frequency information of seismic data. In view of this, we proposed a scale-angle adaptive surface wave separation method based on Shearlet sparse transform. The surface wave model obtained by filtering method and the effective wave can decomposed in Shearlet domain, based on the characteristic differences between surface wave and effective wave in frequency, velocity and direction. At different scales and angles, an adaptive surface wave removal operator based on L2 norm of Shearlet coefficient is developed to remove surface wave information from seismic data. The actual seismic data application results show that compared with the traditional surface wave suppression method, the proposed method can thoroughly separate surface wave and effective wave, and obtain high quality denoising seismic data.
A Numerical Output Technique for Voxler’s ObliqueImages and Its Application
Authors: Liu Haitao , Peng Jun , Hu Jun , Xiong Youliang , Li Huan
Published: December 2023

In geophysical surveys, there will be no measured data at some location where it is inaccessible for placement of survey points or lines. The interpolation data of those locations can be obtained and displayed by using three-dimensional (3D) mapping platform. Based on the study of the file format of ObliqueImage output in Voxler platform, this paper presents a technique for extracting spatial coordinates and physical parameter values of each point in the ObliqueImage. This numerical output technique is used to map the profiled slice across the tunnel axis where boreholes can not be arranged in the electromagnetic wave CT investigation section in a dedicated karst survey of an underwater tunnel in Wuhan, rendering the karst development on the profile across the tunnel axis; after further extension, the point cloud data of bedrock surface and karst caves for building 3D geological model are extracted from isosurface files, which provides data basis for tunnel design and construction digitization.
The Application of Rayleigh Wave Method in the Underground Void Area Exploration
Authors: An Yin , Du Lizhi , Zhang Guoqiang , Wang Yong
Published: December 2023

Underground voiding refers to the phenomenon that abnormal looseness, plate breakage, increase in porosity of underground medium lead to the formation of voids that decrease the stability of stratum and weaken the physical and mechanical properties. For example, road underground voiding will seriously affect the comfort and safety of vehicle driving. At present, the engineering geophysical prospecting technology is mainly used to detect the void area. In this paper, the elastic wave simulation method is used to study the response of the Rayleigh wave method to the underground void of the pavement. The response regularity is explored by adjusting the model parameters. The outdoor experiment is carried out according to the law parameters, and the effectiveness of the elastic wave for the detection of shallow surface voids is verified.
Application of OCTEM in The Detection of Hidden Faults in Urban Underground Space Investigation
Authors: Zhou Chao , Liu Yi , Zhao Siwei
Published: December 2023

At present, the geological survey of urban underground space is currently being carried out in many cities across the country. Choosing appropriate survey methods will make this work more effective. OCTEM is a new exploration method that has emerged in engineering geophysical prospecting in recent years. It has the advantages of portable facilities and strong anti-interference ability, and is suitable for urban geological survey work. In this paper, OCTEM is applied to the hidden fault detection work in underground space survey in Chengdu. The results show that this method can effectively identify the fault fracture zone in the strong interference urban environment. At the same time, the OCTEM results are compared with the application results of the other 2 geophysical methods. The analysis further proves the adaptability and superiority of this method. It provides an effective new method for urban underground space survey work.
Surface-Wave Imaging with Nonrandom Traffic Noise Sources
Authors: Mi Binbin , Xia Jianghai
Published: December 2023

We analyze the influence of nonrandom traffic noise sources on surface wave imaging. With nonrandom traffic noise sources in time (correlated sources), spurious signals are produced in the crosscorrelation functions. With nonrandom traffic noise sources in space (directional sources), phase velocities are overestimated from the retrieved surface waves. The retrieval of surface waves can be improved by stationary-phase segment selection, cross-coherence and stacking of the results from multiple traffic noise sources. Synthetic results demonstrate that cross-coherence and stacking of multiple traffic noise sources makes the source tend to be random distribution in time and suppresses the spurious signals in the crosscorrelation functions. Enhancing the stationary-phase contribution makes more accurate estimation of surface wave phase velocities.
Effect Analysis on Field Acquisition Parameters of Surface Wave Survey - Case Study on The Gobi Desert Field
Authors: Ren Quanchao , Li Zhongsheng , Liu Sitong , Tian Awei , Li Yongxin , Xiao Weiguo , Lu Qiang , Su Wuque , Li Xingwang
Published: December 2023

In this paper, the Gobi Desert landform is used as a test site to analysis the results on surface wave survey. The body wave exploration methods are used to determined velocity structure of the site as a reference standard firstly. Subsequently, different acquisition parameters for surface wave are tested. After comparing the results, the optimal parameters are selected by using the surface wave multi-channel analysis method (MASW). Meanwhile, several theoretical equations for estimating minimum offset, optimum offset, geophone spread length, and resolution of dispersion are demonstrated as the guidelines to organize the real-world data acquisition. Finally, the selected optimal parameters are applied to the data acquisition of total 69 surface wave recorders. The final two-dimensional inversion profile is in good agreement with the known background. It means the method of MASW is feasible in geological surveys on Gobi Desert landform.
Trans-Dimensional Bayesian Inversion of Rayleigh Wave Dispersion Curves for Shallow Surface Two-Dimensional Imaging
Authors: Liu Haonan , Zhang Zhifu , Ma Zhenning , Zhang Jinyung
Published: December 2023

In this study, we achieve 2-D spatial structure directly from dispersion measurements using the reversible jump Markov chain Monte Carlo (rj-McMC) algorithm with a fully 2-D model parameterization. New parsimonious parameterization with low dimensional representation is introduced, which enable us to accurately reproduce the wave velocity field and the associated uncertainties. Field data test demonstrates that the proposed method estimates directly the shear-wave velocity profile with better lateral resolution. The associated uncertainties provide directly interpretable uncertainty on structures of interest.