Artículos (Ingeniería Energética)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11362

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Experimental assessment of a zero liquid discharge system driven by a micro gas turbine
(Elsevier, 2025) González-Almenara, Rafael; García Rodríguez, Lourdes; Sánchez Martínez, David Tomás; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). European Regional Development Fund (ERDF)
This study presents an experimental proof of concept for a zero liquid discharge (ZLD) system applied to seawater desalination. The system concentrates brine through direct-contact heat exchange using the exhaust gases of a solar micro gas turbine, bubbling them through the brine from a reverse osmosis (RO) unit until a dry residue is obtained. The design phase initially involved a hydraulic evaluation to assess gas stream-brine interactions, using a cold air stream to test different configurations and define the working region. Once hot exhaust gases were introduced, preliminary findings guided the correct sizing and internal arrangement of the ZLD system. Initial tests employed low-cost materials to successfully achieve zero liquid discharge. To fully characterise the thermochemical performance, experiments were conducted in batches, even though the process would operate continuously in real applications. After validating the proof of concept, the setup was refined, addressing key aspects such as material selection and optimised geometries to enhance durability and performance.
Temperature and Current Density distributions in a 100 cm2 PEM Fuel Cell: Effects of flow field designs
(Elsevier, 2025) Cabello González, Gracia María; Toharias Góngora, Baltasar; Rosa Iglesias, Manuel Felipe; Guerra Macho, José Julio; Iranzo Paricio, José Alfredo; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); TEP143: Termotecnia
Electro-thermal mapping provides valuable insights into the performance evaluation of polymer electrolyte membrane fuel cells (PEMFCs) by depicting the spatial distribution of current density and temperature. In this study, electro-thermal maps were generated for three different designs of 100 cm2 PEMFC flow fields (conventional serpentine with two different channel depths, and serpentine-tapered). The performance of each design was characterized by analyzing the surface (in-plane) distributions of current density and temperature at different cell voltages. At elevated current densities, a linear increase in the non-uniformity of temperature and current density distribution is observed. The central region of the bipolar plate exhibits higher temperatures, whereas the region with high current densities is situated near the hydrogen inlet, gradually diminishing as the hydrogen depletes towards the outlet. Results show that, in general, the tapered flow field design exhibits better performance with a more homogeneous temperature and current distribution throughout the entire active area. This behavior can be attributed to better water management and gas diffusion towards the electrode due to the acceleration and pressure increase of the reactant fuel gas along the narrowing channel. Novel insights were identified by applying the Current Distribution Mapping (CDM) technique for analyzing current density and temperature in-plane distributions under dynamic load conditions, comparing the different channel depths or tapered designs during the dynamic operation of the cell. During dynamic tests, temperature increased rapidly for increasing loads but the decrease was more slowly when load was lowered, leading to an overall gradual temperature rise and less homogeneous distribution at higher currents, while the current distribution adjusted almost instantly with constant standard deviation during both load increases and decreases.
Mitigating urban heat pains through nature-based cool pavement in extremely hot climates
(Elsevier, 2025) García Melgar, Paulo Javier; Montero Gutiérrez, Paz; Guerrero Delgado, María del Carmen; Cerezo Narváez, Alberto; Sánchez Ramos, José; Álvarez Domínguez, Servando; Ingeniería Energética; European Commission (EC); Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Global warming is intensifying the frequency and severity of heat waves, making urban environments increasingly hostile, especially during the summer months. Pavement surfaces are particularly vulnerable, often reaching extreme temperatures that cause significant thermal discomfort, contact burns and material degradation. This study presents an innovative solution based on nature: a cold pavement system that takes advantage of naturally cooled subsurface water to reduce surface temperatures by conduction, without relying on evaporation or water consumption due to the absence of capillarity. The system is particularly suitable for hot climates and outdoor public spaces where users can walk barefoot, such as coastal promenades or water parks. To evaluate its performance, a digital thermal model was developed and experimentally validated in real conditions in Seville, Spain, during the summer of 2023. A sensitivity analysis identified optimal design parameters, including pavement thickness, thermal conductivity, absorptivity and water heat exchange. Results indicate that this passive cooling strategy can reduce surface temperature by up to 20 ◦C compared to conventional pavements, while maintaining safe thermal conditions for more than 80 % of the exposure time and systematically avoiding harmful contact thresholds. This nature-based approach demonstrates great potential to improve outdoor urban thermal comfort, mitigate heat-related health risks, and support the development of more sustainable and climate-resilient urban environments.
Surface processes optimisation in a novel CO2-based electrothermal energy and geological storage trigeneration system
(Elsevier, 2025-10) Carro Paulete, Andrés; Ortiz Domínguez, Carlos; Unger, S.; Stoikos, A.; Kyriakides, A. S.; Tsimpanogiannis, I. N.; Becerra Villanueva, José Antonio; Voutetakis, S.; Hampel, U.; Chacartegui, Ricardo; Ingeniería Energética; European Commission (EC)
Electrothermal energy storage is a promising technology for high penetration of renewable energy. In recent years, the integration of this energy storage system with geological CO2 storage has been introduced. The system consists of a reversible heat pump formed by transcritical CO2 cycles with thermal storage at two temperature levels, enabling the simultaneous operation of geological CO2 storage and the storage/production of renewable electrical energy. This work focuses on studying high and low-temperature thermal energy storage. Step heating on the high-temperature side allows for better integration of the supercritical and subcritical temperature profiles of the CO2 and the thermal storage fluid. Thermal storage at different temperature levels provides a higher turbine inlet temperature, improving the efficiency of the power production cycle and increasing heating applications such as district heating or domestic hot water. Considering four high-temperature tanks, round-trip efficiency increases from 52.8 to 55.4 %. It presents a thermal demand coverage range of about 20–150 °C, with temperature increases of approximately 30 °C. The phase change temperature shift on the low-temperature side directly impacts electric power production and enables new cooling applications. The system's efficiency increases as the low-temperature phase change temperature decreases, reaching 58.7 % at −30 °C. Using alternative configurations in the transcritical CO2 cycle, such as the recuperative cycle and multi-stage compression and expansion, high-efficiency values can be maintained with lower system requirements.
Green hydrogen from renewable surplus: Production and storage potential in Spain's 2040 energy horizon
(Elsevier, 2025) Back, Constantin; González Morán, Laura; Iranzo Paricio, José Alfredo; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); TEP143: Termotecnia
This work studies the potential of hydrogen production from surplus electricity, in line with Spain’s ambitious decarbonization goals. By simulating the planned 2040 electricity system with increased renewable energy capacity, it indicates a seasonal imbalance in production. The study estimates a surplus of 17.33 TWh over the Spring (9 TWh), Summer (6.2 TWh) and Autumn (2.1 TWh) months, enabling the production of 4.33 × 10 9 m 3 of hydrogen and requiring around 60 salt caverns for storage in its entirety. In addition, it identifies suitable locations for the construction of salt caverns. Already existing Salt caves can currently be found in the “Torrelavega","Sales de Monzon”, and “Jumilla/Pinoso” districts although currently only used for the production of brine. However, the geological characteristics of these deposits demonstrate the feasibility of developing additional salt caverns. The research suggests using excess summer electricity to produce hydrogen through electrolysis to potentially make up for the winter deficit of 5.69 TWh. Overall, it highlights the feasibility of employing hydrogen to address seasonal energy variations to advance Spain’s renewable energy goals.
Vision-based adaptive control system for fluidized bed reactors
(Elsevier, 2025-09) Anweiler, Stanisław; Krok, Marek; Kołodziej, Szymon; Chacartegui, Ricardo; Becerra Villanueva, José Antonio; Sikora, Małgorzata; Wasilewska, Barbara; Przysiężniuk, Dawid; Ingeniería Energética; Universidad de Polonia; Ministerio de Ciencia. Polonia; Ministerio de Ciencia e Innovación (MICIN). España
In process engineering, precise, automatic, and dynamic identification of two-phase structures remains a challenging yet essential task, particularly for effectively controlling pneumatic systems handling solid particles. Complex interactions between gas and solid phases and variable flow geometries complicate the precise control of fluidized beds. This study evaluates an adaptive, vision-based flow control system designed for fluidized bed reactors, using real-time image analysis to characterize flow structures. A self-developed air flow valve regulator system, combined with a programmable logic controller (PLC) and dynamic image feedback, enables this innovative control approach. By analyzing grey-level signals within specified regions of interest (ROIs), the system accurately differentiates between critical fluidization regimes: bubbling, plugging, and turbulent flow. The control algorithm dynamically adjusts the flow rate, achieving a mean square error of 6.98 m3/h, underscoring the system’s reliability and potential for further optimization. Additionally, safeguards were implemented to prevent material loss at high airflow thresholds, enhancing system stability and safety. The findings demonstrate the potential of adaptive vision-based control for fluidized bed automation, offering an advanced solution for real-time monitoring and precise flow regulation in complex two-phase processes.
Optimisation of metastable supercooled liquid phase change material for long-term heat energy accumulation
(Elsevier, 2025) Ryšavý, Jiří; Čespiva, Jakub; Sangeetha, Thangavel; Teicht, Christian; Charvát, Matěj; Yan, Wei Mon; Chacartegui, Ricardo; Ochodek, Tadeáš; Universidad de Sevilla. Departamento de Ingeniería Energética; Technology Agency of the Czech Republic (TAČR); European Union (UE)
This research study investigates sodium acetate trihydrate as a metastable supercooled liquid phase change material for long-term heat energy storage and is an efficient evaluation of various sodium acetate trihydrate-to-water ratios and heat exchanger geometries to enhance storage efficiency. Experimental modules with spiral and toroid squiggle heat exchangers were developed to assess energy retention during liquefaction, sensible heat discharge, and latent heat discharge phases. Experimental outcomes indicate that the toroid squiggle design extends latent heat discharge duration by up to 35 min compared to the spiral exchanger, reaching a maximum of 29 min. The optimal sodium acetate trihydrate-to-water ratio was 92 %, balancing high theoretical latent heat capacity (93.6 Wh) and low theoretical to real latent heat capacity ratio with phase stability. The toroid squiggle exchanger with the mentioned accumulation substance demonstrated better heat transfer, maintaining energy output above 100 W for 11 min and above 50 W for 35 min, while the spiral design showed lower values, retaining above 100 W for only 7 min and above 50 W for 26 min. Furthermore, specific heat capacity measurements showed that sodium acetate trihydrate-to-water 92:8 ratio (SAT 92) exhibited specific heat values of 2.1 kJ/kg·K in the solid phase and 5.0 kJ/kg·K in the liquid phase, confirming its strong thermal storage potential with minimal phase instability. The conclusions have highlighted the importance of optimizing heat exchanger geometry and sodium acetate trihydrate composition for sustainable energy storage and these significant insights will contribute to improving seasonal heat accumulation technologies, particularly in synergy with renewable energy systems.
Clean and zero-emission urban buses: Compliance with EU regulations and f leet transition in Seville
(Elsevier, 2025-09-30) Tagua Navarrete, Miguel Ángel; Serrano Reyes, Javier; Vélez Godiño, José Antonio; Jiménez-Espadafor Aguilar, Francisco José; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería de la Construcción y Proyectos de Ingeniería
The EU public transport sector is dominated by diesel and natural gas buses, but fleet structures are rapidly changing. EU climate laws drive two strategies: one for bus manufacturers and another for public transport operators (PTO), with different timelines. PTOs must progressively replace fleets with clean and zero-emission buses. This paper develops bus replacement strategies aligned with EU standards, focusing on cost minimization and CO 2 emission reduction. Three propulsion technologies (diesel, compressed natural gas, and electric) and two bus types (regular and articulated) are analyzed. The strategies consider acquisition, operational, and service costs, along with CO 2 emissions. The proposed approach, applied over a 10-year period, uses real-word data from Seville (Spain) PTO to meet EU standards for 2025–2035. Operational data allow precise energy demand estimation, considering propulsion, climatization air compressor, and auxiliaries. CO 2 culations show that CNG buses emit 24 % more CO 2 emissions calper km than diesel buses. Optimization results indicate that a CO 2 minimization strategy reduces emissions by 16.3 %, with only a 6.7 % cost increase compared to the minimal-cost strategy.
A novel two-dimensional effectiveness-NTU method for high-temperature cascade latent heat storage
(Elsevier, 2025-11-01) Al-Saaidi, Hussein Alawai Ibrahim; López Román, Antón; Prieto Ríos, Cristina; Universidad de Sevilla. Departamento de Ingeniería Energética; European Union (UE)
This study presents a novel two-dimensional effectiveness number of transfer unit ( ε-NTU) method to characterise and optimise cascade latent heat storage (CLHS) systems, incorporating metal wool enhancement for improved thermal performance. The proposed model provides a more accurate and computationally efficient alternative to conventional one-dimensional approaches for analysing heat transfer in high-temperature latent heat storage (LHS) applications. Current performance evaluation methods still lack precision due to the reliance on simplified assumptions regarding material properties and heat transfer dynamics. Moreover, most enhancement strategies focus on single-PCM systems, necessitating dedicated research efforts for CLHS-specific solutions. Validation through computational fluid dynamics (CFD) simulations demonstrates strong agreement, confirming the method’s reliability in predicting thermal behaviour during both charging and discharging processes. The results reveal that the cascade configuration reduces thermal resistance and enhances heat transfer efficiency, while the addition of metal wool increases the effectiveness of the system by up to 54% in single latent heat storage (SLHS) and 20% in CLHS without additives. These findings establish the two-dimensional -NTU method as a robust design and optimisation tool for next-generation thermal energy storage systems in renewable energy real-world applications.
A numerical study on heat transfer for serpentine-type cooling channels in a PEM fuel cell stack
(Elsevier, 2024) González Morán, Laura; Suárez Soria, Christian; Iranzo Paricio, José Alfredo; Han, Lei; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
The aim of this work is to analyse numerically the heat transfer for serpentine-type cooling channels in a PEM fuel cell stack. The effect of the coolant type, the flow rate, the inlet temperature, the presence of the thermal contact resistance and the gas diffusion layer, the bipolar plate material and the cooling channels design was studied with CFD simulations in a 100 cm 2 active area cell with serpentine cooling channels to analyse the refrigeration capability of a PEMFC stack. A novel correlation for the Nusselt number is presented. The originality of the proposed correlation lies in the fact that it can be used for a comprehensive range of operating conditions, coolant fluids and bipolar plate materials, assessing the influence of those variables on the temperature distributions within the cell. Results of this study determined that mass flow and the bipolar plate thermal conductivity presented a higher effect on the refrigeration capability of a PEMFC stack. Results obtained in terms of the Uniform Temperature Index showed that values above 3.65 % lead to temperature differences in the membrane higher than 5 K, which could cause degradation problems.
District heating based on biogas from wastewater treatment plant
(Elsevier, 2019-08-01) Picardo Pérez, Alberto; Soltero Sánchez, Víctor Manuel; Peralta-Álvarez, María Estela; Chacartegui, Ricardo; Universidad de Sevilla. Departamento de Ingeniería del Diseño; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. TEP992: Diseño e Ingeniería; Universidad de Sevilla. TEP137: Máquinas y Motores Térmicos
Wastewater treatment plants have a relevant role within the circular economy chain of the cities. They purify contaminated waters and materials and biogas can be recovered from their processes. This article analyzes the potential integration of District Heating systems with wastewater treatment plants, using the biogas generated, in combination with natural gas, to supply heat and domestic hot water to the municipalities integrated in the wastewater network. A methodology is proposed to analyze the potential for implementation of these systems based on the evaluation of the requirements of transmission and distribution networks and cost benefit analysis. As case study this methodology was applied to 88 sewage treatment plants located in the Atlantic and Continental regions of Spain. Each wastewater treatment facility provides services to more than 50,000 equivalent users. The analysis is oriented to district heating system in cities with high/medium urban wastewater load. Analytical expressions to estimate capital expenditures as function of district heating network capacity have been obtained from data of the municipalities under analysis. The results for the analysed region show a potential for CO₂ emissions savings of 1.8 Mt per year with an overall investment of 2,854 M euros.
Ammonia as energy source for solid oxide fuel cell technology
(Elsevier, 2025-06) Loboichenko, Valentyna; Casado-Manzano, Manuel; Navas Herrera, Sergio Jesús; Toharias Góngora, Baltasar; Rosa Iglesias, Manuel Felipe; Iranzo Paricio, José Alfredo; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
This review shows the complex transformation of ammonia as an energy carrier and focuses on its use in the fuel cell technology. Promising characteristics of ammonia are noted, which allow it to be used as a carbon-free fuel. The main methods of ammonia production, the current state of the transport and distribution systems of ammonia, as well as its storage are shown. Using bibliometric analysis, the current state of the issue of ammonia fuel cells is studied. The processes of direct and indirect use of ammonia as a fuel in solid oxide fuel cells are considered in detail. It is noted that the final level of technical and economic improvements in ammonia fuel cells of various designs has not yet been achieved. The features of the use of ammonia in PEM, alkaline, and solid oxide fuel cells are analyzed. The influence of the material and catalyst on the characteristics of the electrochemical process is shown, and the factors affecting the degradation of the fuel cell are considered. The need for further search for effective catalysts is noted. The options for applications in fuel cell technology show the promise of using ammonia as a fuel in a fuel cell in various modes of transport. The presented review shows the way to integrate ammonia, through its use in fuel cells and particularly in solid oxide fuel cells, into the structure of carbon-free energy of the future, outlining the frameworks of its further application. The results obtained are expected to be useful to a wide range of specialists, including all participants in the energy market at the national and international level.
Methanol to dimethyl ether (DME) assessment toward thermochemical energy storage
(Elsevier, 2025-04) Rodríguez Pastor, Diego Antonio; Soltero Sánchez, Víctor Manuel; Chacartegui, Ricardo; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería del Diseño; European Commission. Fondo Social Europeo (FSO); Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP137: Máquinas y Motores Térmicos
The production of alternative renewable fuels is imperative for decarbonising hard-to-electrify sectors. Dimethyl ether (DME) is an aerosol propellant and a low-emission candidate for fossil fuel substitution. The main conventional DME production process is the indirect dehydration of methanol produced from fossil natural gas. This work analyses the direct use of green methanol for conversion to renewable DME by integrating a thermochemical energy storage system through dissociating methanol to syngas by solar power and its subsequent synthesis by the novel direct synthesis process to DME. The integrations act as storage methods via exothermic discharge to produce power in alternative power cycles, and they also produce high-quality green DME for heat production in industries, cooking, and as a substitute for fossil diesel. Three novel pathways are proposed: integrating power blocks in indirect green methanol-DME processes, direct DME synthesis of syngas from solar methanol decomposition, and solar methanol-methanol TCES adapted for DME production. Direct DME synthesis TCES offers global efficiencies >20 % and competitive LCOE values compared to current CSP with molten salt storage. Methanol-methanol TCES-to-DME achieves RTEs up to 30 % and levelized costs <270 €/MWh. The results show the interest of the proposed configurations for further development
Green methanol production from photovoltaics in Europe
(Elsevier, 2025-12-01) Rodríguez Pastor, Diego Antonio; Soltero Sánchez, Víctor Manuel; Chacartegui, Ricardo; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería del Diseño; Ministerio de Ciencia e Innovación (MICIN). España
The European Union’s objective for non-biological fuels is 10 Mt by 2030. The massive implementation of green hydrogen facilities predicts cost overruns for adapting the existing industry towards H 2-ready, making the development of alternative e-fuels imperative. Based on European GIS data, this work analyses the potential implementation of green methanol from CO 2 maximum volumetric blends of 5–20 % H 2 capture in existing industries. The study is based on hydrogen fraction limits on existing natural gas grids, with . The analysis of boundary conditions based on water resources and proximity to the networks yields 3016 potential municipalities for implementing green methanol valleys. The analysis projects a potential of ~30 Mton H capture capacity above 7 Mton CO 2 2 /year in PV to produce 5 Mton of methanol, with a carbon /year. The economic analysis of different scenarios shows that in 2030, the levelized cost of methanol could reach values around ~450 € /ton MeOH, with IRR>15 %, showing the viability of the approach.
Study of the electrodeposition of conductive polypyrrole doped saccharin coatings on 316L stainless steel plate for PEMFC application
(Elsevier, 2025) Ben Jadi, S.; Bahend, K.; El Fazdoune, M.; Iranzo Paricio, José Alfredo; García-García, Francisco J.; Bazzaoui, M.; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
The study investigates the electrosynthesis of pyrrole doped with sodium saccharin as a protective coating for AISI 316L bipolar plate. Electropolymerization durations are systematically varied to optimize corrosion inhibition under different concentrationa of the aggressive environment of typical of PEMFC operation. Weight loss measurements indicated that films synthetized during 30 min period exhibit superior corrosion resistance compared to those produced under shorter durations. Electrochemical assessments, including potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS), demonstrate that the sodium saccharin doped PPy coating significantly reduces the polarisation density of 316L. detailed structural and morphological analyses were conducted using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS confirmed the successful incorporation of the saccharin dopant in the PPy matrix with dopant rates increasing under aggressive acidic condition. While SEM reveals that PPy coatings formed through extended electropolymerization enhance corrosion resistance on AISI 316L through their densely cauliflower structure. The enhanced long-term corrosion protection observed can be attributed to the robust physical barrier and source of anodic protection compared to uncoated 316L.
Velocity-space analysis of fast-ion losses measured in MAST-U using a high-speed camera in the FILD detector
(IOP Publishing, 2025) Velarde Gallardo, Lina; Rivero Rodríguez, Juan Francisco; Galdón Quiroga, Joaquín; Williams, T.; Rueda Rueda, José; Cano Megías, Pilar; Chacartegui, Ricardo; García Muñoz, Manuel; Sanchis Sánchez, Lucía; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Consejería de Transformación Económica, Industria, Conocimiento y Universidades. Junta de Andalucía; European Research Council (ERC)
A fast-ion loss detector (FILD) was installed for the first time at the mega amp spherical tokamak—upgrade (MAST-U) spherical tokamak during its upgrade in 2021. A new CMOS camera was installed in the MAST-U FILD acquisition system to provide high spatial resolution (1.1 MPx) with an acquisition frequency of up to 3.5 kHz. This camera has enabled the systematic analysis of the velocity-space of the fast-ion losses measured in MAST-U presented in this manuscript. The main parameters that determine the FILD measurement have been analysed to maximise the signal in the detector: the orbit-following code ASCOT predicts an inverse relation between the FILD signal and the probe’s relative distance to the separatrix. This prediction has been validated experimentally, enabling the measurement of fast-ion losses in the flat-top phase of the discharge; furthermore, ASCOT simulations show a big impact of the edge safety factor (q95) on the toroidal deposition of the prompt losses, indicating that the signal in the MAST-U FILD can be maximised by running scenarios with | q 95 | < 6 . This prediction was validated experimentally by a scan in the toroidal magnetic field. The experimental resolution of the MAST-U FILD has been evaluated for a typical MAST-U scenario with 750 kA plasma current. The results show that the diagnostic resolution is in the order of 0.5 to 1 degree in pitch angle, and of 1 to 3 cm in gyroradius in current scenarios. A systematic analysis of the velocity-space of the losses shows that the measured gyroradii of the prompt losses match those of the neutral beam injector injection energies within the resolution of the diagnostic. The experimentally measured pitch angles have been compared with ASCOT simulations, and it has been found that the agreement is better for scenarios heated with the on-axis beam, since this beam enables measurements of the magnetic field pitch angle. This analysis has been applied to a discharge where type-III ELM-induced fast-ion losses were measured, showing that the ELMs result in an increase in the FILD signal, and that the losses are coming from passing orbits.
Modelling Pollutant Dispersion in Urban Canyons to Enhance Air Quality and Urban Planning
(MDPI, 2025) Ruda Sarria, Francisco; Guerrero Delgado, María del Carmen; Monge Palma, Rafael; Palomo Amores, Teresa Rocío; Sánchez Ramos, José; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Air pollution in urban street canyons presents a serious health risk, especially in densely populated areas. While previous research has explored airflow characteristics in these canyons, it often lacks detailed data on pollutant dispersion and the effects of wind speed on airflow patterns and vortex formation. This study uses Computational Fluid Dynamics (CFD) to deliver quantitative measurements of pollutant dispersion rates and qualitative insights into airflow patterns across various street canyon morphologies. The analysis examines a range of aspect ratios (ARs), from wide (AR = 0.75) to narrow (AR = 4.5), and different wind speeds to evaluate their effects on pollutant dispersion. Findings indicate that purging flow rates decline as the AR increases, with a more pronounced decrease at lower AR values. In narrower streets, airflow patterns are particularly sensitive to wind velocity, leading to unexpected vortices that hinder effective pollutant dispersion. By incorporating these insights into urban design strategies, cities can enhance street ventilation, thereby reducing pollutant concentrations and improving public health. This study also tests a specific street layout in Seville to predict pollutant accumulation under various conditions, assessing health risks based on World Health Organization guidelines. Ultimately, this research aids in developing healthier, more sustainable urban environments.
Beyond Thermal Conductivity: A Review of Nanofluids for Enhanced Energy Storage and Heat Transfer
(MDPI, 2025-02) Mirahmad, Ali; Shankar Kumar, Ravi; Pato Doldán, Breogán; Prieto Ríos, Cristina; Díez-Sierra, Javier; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España
The development of nanofluids (NFs) has significantly advanced the thermal performance of heat transfer fluids (HTFs) in heating and cooling applications. This review examines the synergistic effects of different nanoparticles (NPs)—including metallic, metallic oxide, and carbonaceous types—on the thermal conductivity (TC) and specific heat capacity (SHC) of base fluids like molecular, molten salts and ionic liquids. While adding NPs typically enhances TC and heat transfer, it can reduce SHC, posing challenges for energy storage and sustainable thermal management. Key factors such as NP composition, shape, size, concentration, and base fluid selection are analyzed to understand the mechanisms driving these improvements. The review also emphasizes the importance of interfacial interactions and proper NP dispersion for fluid stability. Strategies like optimizing NP formulations and utilizing solid–solid phase transitions are proposed to enhance both TC and SHC without significantly increasing viscosity, a common drawback in NFs. By balancing these properties, NFs hold great potential for renewable energy systems, particularly in improving energy storage efficiency. The review also outlines future research directions to overcome current challenges and expand the application of NFs in sustainable energy solutions, contributing to reduced carbon emissions.
Hybrid hydrogen-electricity production using spherical tokamaks: a cost-driver sensitivity study and techno-economic analysis
(Iop Publishing Ltd, 2025) Hidalgo Salaverri, Javier; Griffiths, T; Conti, Z. X.; Cano Megías, Pilar; Chacartegui, Ricardo; Bluck, M; Ayllón Guerola, Juan Manuel; García Muñoz, Manuel; Viezzer, Eleonora; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación; European Union (UE)
Hybrid fusion power plants, which produce both hydrogen and electricity, are proposed as a way to decarbonise the fossil-fuel-dominated primary energy market and improve plant economics. The main cost drivers of a fusion power plant based on a spherical tokamak have been identified using statistical analysis (Morris and Sobol methods) from a wide range of cases obtained with the systems code PROCESS. The analysis reveals the importance of plasma physics and reactor geometry on power plant economics. Three scenarios of advancing technophysical assumptions (conservative, moderate and optimistic) have been chosen to study the integration of the fusion reactor with the power block (Rankine, He-Brayton or super-critical-CO2-Feher) and with the PEM electrolyser. The super-critical-CO2 cycle returns the best results for the studied temperature range (500 ◦C–800 ◦C), with an efficiency between 40%–56%. The modelled PEM is in line with current commercial models with a consumption of 51.97 kWh kg−1 H2. The economic feasibility of these scenarios has been explored for a set of learning factors that consider the cheapening of the capital costs tied to experience. The LCOE of these scenarios have been compared against current price ranges of solar, wind and fission power and the LCOH against PEM prices, showing that the moderate and optimistic scenarios could be competitive for learning factors lower than 0.5 and capacity factors larger than 0.7. An extrapolation of the optimistic scenario shows that the hybrid fusion power plant in the French and German market can improve the plant profits by 15% and 66% respectively.
Assessment of carbon dioxide transcritical cycles for electrothermal energy storage with geological storage in salt cavities
(Elsevier, 2024-10) Carro Paulete, Andrés; Carneiro, J.; Ortiz, Carlos; Behnous, D.; Becerra Villanueva, José Antonio; Chacartegui, Ricardo; Universidad de Sevilla. Departamento de Ingeniería Energética; European Union (EU). Horizonte Europa; Universidad de Sevilla. TEP137: Máquinas y Motores Térmicos
Carbon capture, utilisation, and storage (CCUS) technologies are envisaged as critical actors in the energy transition and climate change mitigation framework. Despite the recent advances in CCUS implementation, there is still significant scope for their growth and improvement. On the other hand, developing new large-scale energy storage systems is a key factor for the massive deployment of renewable energy systems. Technologies such as the electrothermal energy storage system based on carbon dioxide transcritical cycles incorporating geological storage (CEEGS) can contribute to both fields. Preliminary studies have shown that the integrated storage system can operate with roundtrip efficiencies exceeding 50%, injecting over 1 million tons of captured carbon dioxide (CO2) annually. It is an early-stage technology with open challenges for successful development, such as an adequate balance between the high- and low-temperature thermal storage reservoirs or the operation definition between the electrothermal system and the carbon dioxide injection and recovery. Underground pressures will oscillate with the charge/discharge process, with operational implications and constraints. Advancing in the concept requires the definition of optimised operation. This work presents a novel analysis of the adaptation of CO2 transcritical cycles to include injection and production processes with the specific scenario of salt cavities. It considers new modifications to adapt the transcritical cycles in closed-mode operation to the conditions required by the salt cavities injection and production processes. Different case studies are evaluated, evaluating the impact of injection and geological storage, production and surface storage, and reinjection into the geological formation. The analyses show roundtrip efficiencies within the range of 49.1–73.0% when the injection, production, and reinjection processes are executed.

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