Artículos (Ingeniería Energética)

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

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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, J.; Griffiths, T; Conti, ZX; 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.
Experimental Validation of the Potential of Cross-Ventilation Strategy as a Natural Cooling Technique Integrated in a Real Historic Building
(MDPI, 2025-02) Palomo Amores, Teresa Rocío; Ruda Sarria, Francisco; Castro Medina, Daniel; Cano Valera, Teresa; Sánchez Ramos, José; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; European Commission (EC); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TEP143: Termotecnia
Natural ventilation in hot climates represents a key strategy to reduce the depen- dence on mechanical cooling systems, especially in historic buildings, where it is essential to balance thermal comfort and heritage conservation. This study analyses the effective- ness of various natural ventilation strategies in a historic building located in Écija, Seville, which is characterised by a warm climate with nocturnal thermal dips. Experimental data obtained during a summer monitoring campaign were used to validate computational fluid dynamics (CFD) models and thermal simulations. In addition, an efficiency index was defined to quantify the indoor temperature reduction. The results show a cooling efficiency close to 40%, achieving an average reduction of 3 ◦C in the indoor temperature during the summer. Simulations of different modes of operation of natural ventilation show a 30% improvement in comfort hours according to Spanish regulations and a 50% reduction in the thermal difference during non-comfort hours. This work demonstrates that natural ventilation can significantly improve indoor conditions, offering a sustainable and replicable approach for historic buildings in hot climates.
Natural cellulose fibers from Agave Americana L. ASPARAGACEAE as an effective adsorbent for mercury in aqueous solutions
(Springer, 2025-02) Sánchez Moreno, Hugo; García Rodríguez, Lourdes; Recalde Moreno, Celso; Universidad de Sevilla. Departamento de Ingeniería Energética; European Commission (EC)
This study investigated the use of functionalized cabuya fibers (FCF) as an effective adsorbent for Hg (II) removal from aqueous solutions. The composition, surface properties, and morphology of the FCF were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and Fourier transform infrared spectroscopy (FTIR). The effects of the pH, contact time, temperature, adsorbent dosage, and initial Hg (II) concentration on the adsorption process were studied. Under optimized experimental conditions, FCF achieved a removal efficiency exceeding 92%, with a maximum adsorption capacity of 8.29 mg/g. The experimental data for the FCF isotherm were analyzed using the Langmuir, Freundlich, DR, and Temkin adsorption models. Notably, the Langmuir isotherm exhibited the highest R² value of 0.99, indicating the model’s strong applicability. The pseudo-second-order kinetic model k2 = 0.42 mg/g.min was employed to elucidate the adsorption mechanism. Thermodynamic studies of the adsorbent FCF were conducted, and ΔG° (-6.16 kJ/mol), ΔH° (36.29 kJ/mol), and ΔS° (141.98 kJ/mol·K) were calculated, assessing the feasibility of the process. Additionally, the desorption results of FCF were evaluated, demonstrating that it can be reused for up to three cycles, achieving adsorption rates of 74% and 62% in the third cycle. This indicates its stability and recycling capacity. Finally, the effectiveness of the FCF was demonstrated by eliminating approximately 91% of Hg (II) from real mineral water samples in Ecuador. These results highlight the p of FCF as promising, eco-friendly, and sustainable adsorbents for the remediation of Hg (II) contamination in aquatic systems.
Implications of the Urban Heat Island on the selection of optimal retrofitting strategies: A case study in a Mediterranean climate
(Elsevier, 2022-07) Romero Rodríguez, Laura; Sánchez Ramos, José; Guerrero Delgado, María del Carmen; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; European Commission (EC); European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla. TEP143: Termotecnia
The Urban Heat Island (UHI) is a significant phenomenon that currently receives much attention from the scientific community due to its importance on the environment, and it is mostly regarded as a merely negative event. However, there is a clear knowledge gap to investigate its influence when choosing optimal retrofitting interventions in buildings. A replicable methodology is thus needed, also to allow the comparison between different studies, which is currently an intricate task. The aim of this study is to develop such a methodology, using hourly rural and urban data to create temperature baselines and improve building simulations. An evaluation of the UHI impacts on building consumptions is presented, together with the repercussions on the energy savings achieved by retrofit interventions. The results considering case studies in Seville (Spain), in a Mediterranean climate, show that the heating demands are always overestimated when the model driven by rural climate data is used instead of the urban climate model. Conversely, the cooling demands are always underestimated in every considered scenario. In addition, the climate does not considerably influence the decision-making process to choose the optimal retrofitting alternatives, although the actual values of energy demand differ greatly.
Examining the reasons for changes in buildings’ energy consumption in the United States, China and the European Union
(Elsevier, 2025-04) González Torres, María; Pérez-Lombard, Luis; Clementi, Enrico Luca; Coronel Toro, Juan Francisco; Universidad de Sevilla. Departamento de Ingeniería Energética
Buildings are responsible for one third of global operational energy consumption and greenhouse gas (GHG) emissions. Addressing their impact requires the development and monitoring of effective policies, supported by detailed and costly data on building stock and energy use as well as their corresponding analysis. The paper proposes a pyramidal approach to decompose buildings’ energy use into drivers —activity, structure, and efficiency— considering factors like population, floor area, urbanisation, building size, occupancy and climate. Energy-use intensity measures efficiency, while shifts among the residential and tertiary subsectors are captured as structural impacts. The relevance of the methodology is underscored by its potential to assess and quantify the causes of energy consumption changes, guiding policy-making. Applying this approach to China, the United States (US) and the European Union (EU), the paper criticises the lack of data, disaggregates energy consumption changes, outlines policy implications and validates the methodology’s added value. The analysis reveals the increased floor area as the primary driver of rising energy consumption over the past two decades (contributing to changes by 9% in the US, 24% in the EU and 97% in China). This may be reduced by managing urbanisation rates and compensated by an improvement in efficiency. While this has been sufficient to stabilise consumption in the EU, a slight rebound is observed in the US due to the increase in population and in the demand for buildings per capita. In China, the urbanisation trend behind the rise in energy demand is approaching EU levels, highlighting the importance of mindful actions to ensure the sustainability of future expansion. Despite the limited geographical coverage, this study provides a pertinent analysis of almost half of the building energy consumption in the world (China, the US and the EU), offering insights into the sector’s current state and directions for future policy development.
Unlocking synergistic benefits of the calcium looping-calcium hydroxide integration for energy storage: A perspective on sorbent performance
(Elsevier, 2025-01) Arcenegui Troya, Juan Jesús; Carro Paulete, Andrés; Ortiz Domínguez, Carlos; Chacartegui, Ricardo; Perejón Pazo, Antonio; Pérez Maqueda, Luis A.; Sánchez Jiménez, Pedro Enrique; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Química Inorgánica; Agencia Estatal de Investigación. España; European Union (UE)
Calcium Looping has recently attracted attention as a high temperature thermochemical energy storage system. However, significant sintering due to the high temperatures hampers the recyclability of CaO. Hydration and hydroxylation has been explored as a method to regenerate the spent CaO. This study investigates a novel synergistic integration of carbonation (CaCO3/CaO) and hydroxylation (CaO/Ca(OH)2) reactions. Calcination was conducted in N2 and N2/H2O mixtures with 29 % steam content. Carbonation was conducted in CO2/H2O mixture with similar steam concentrations. Results show that steam plays a dual role: during calcination, it promotes the formation of large pores on the CaO surface, and during carbonation, it enhances mineralization, resulting in larger CaCO3 grains. Also, steam promotes CO2 diffusion through the CaCO3 layer and, at the same time, significantly mitigates the deactivation of CaO along the cycles. Specifically, sequential calcination/ carbonation cycles without steam yield a residual conversion value of 0.14. Steam injection improved residual conversion to 0.27. Alternatively, the interleaving of hydroxylation/dehydroxylation cycles in the sequence further increased this value to 0.64 without steam and up to 0.76 with steam injection. Hydroxylation/dehydroxylation cycles alone demonstrated high stability, with a residual conversion of 0.98 when interleaved with calcination/carbonation cycles under 29 % steam conditions. Additionally, frequent hydroxylation/dehydroxylation cycles improve overall conversion stability, highlighting their synergistic benefits within the integrated process. This work underscores the potential of integrating Calcium Looping with Calcium Hydroxide for improved multicycle performance and opens pathways for scaling experiments to pilot systems, alongside assessing the efficiency and economic viability of this integrated approach.
Development of copper metal wool incorporated in a latent thermal energy storage tank for improved charging and discharging
(Elsevier, 2025-04) Mani Kala, Saranprabhu; Ribezzo, Alessandro; Zsembinszki, Gabriel; Borri, Emiliano; Prieto Rios, Cristina; Cabeza, Luisa F.; Universidad de Sevilla. Departamento de Ingeniería Energética; European Union (UE). H2020; Agencia Estatal de Investigación. España
The thermal energy storage tank is an essential component of a conventional thermal energy storage system. Nevertheless, low charging and discharging rates is one of the different problems associated with them. Many research studies were conducted to improve the charging and discharging characteristics of thermal energy storage tanks. Those include the addition of nanoparticles, heat pipes, metal foams, and encapsulation of the phase change material. Even though those approaches improved the thermal performance of the storage tank, they also promoted some problems, like nanoparticle deposition, suppression of natural convection, and reduced energy density. This study, used a different approach to improve the thermal performance, integrating copper metal wool of two discrete thicknesses perpendicular to the heat transfer fluid carrying tubes. Accordingly, with two different packaging factor four different configurations of metal wool-packed tanks were developed and compared against the reference, i.e., a conventional shell and tube tank. The thermal performance of the developed cases was tested using a custom-built test rig. The integration of copper metal wool reduced the charging and discharging time significantly. However, the fully stacked fine fibre wool packed tank showed a remarkable 85% reduction in solidification time and a 37.4% reduction in melting time compared to the conventional shell and tube tank. Moreover, it showed a higher mean power than all the developed cases, with 414% enhancement during the discharging cycle and 42% during the charging cycle. Thus, the incorporation of metal wool into a tank is an effective way to enhance its thermal performance.
Forecasting urban temperatures through crowdsourced data from Citizen Weather Stations
(Elsevier, 2024-07) Romero Rodríguez, Laura; Guerrero Delgado, María del Carmen; Castro Medina, Daniel; Sánchez Ramos, José; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Universidad de Sevilla. TEP143: Termotecnia
This work explores the potential of using crowdsourced data from Citizen Weather Stations (CWS) to forecast urban temperatures. Five case studies were selected (Madrid, London, Rome, Paris and Berlin), using data from the manufacturer Netatmo to gather the hourly temperatures of the years 2021 and 2022 for 776 CWS. A quality-control process was implemented to enhance data accuracy, and heat maps were generated. Multiple linear regression models were created for each CWS and month using only reference weather data as input, resulting in the development of accurate models (RMSE lower than 1.5 °C) for an average of 374 CWS. Then, reference weather predictions were used on the 2nd of April 2023 to forecast the hourly temperatures of those CWS for the period from the 3rd to the 9th of April (168 h). The outcomes showed that accurate CWS data and precise prediction models for the reference weather are crucial to improve the accuracy of the forecasts using crowdsourced data. The study demonstrates the potential benefits of using CWS data and simple models to forecast urban temperatures in a cost-efficient way even 168 h ahead, with implications for various sectors such as urban planning, energy consumptions, health impacts, or climate change adaptation strategies.
Nature-based cool pavements for urban overheating mitigation: Experimental proof of concept
(Elsevier, 2025-01) García Melgar, Paulo Javier; Guerrero Delgado, María del Carmen; Montero Gutiérrez, Paz; Romero García, Cristian; Sánchez Ramos, José; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Universidad de Sevilla. TEP143: Termotecnia
Global warming is leading to more frequent and intense heat waves, transforming urban areas into inhospitable environments, particularly during the summer, due to the exacerbation of the urban overheating effect. Outdoor pavements, which account for 20–40 % of urban surfaces, play a crucial role in this phenomenon due to their dark colour and low albedo, resulting in high surface temperatures and the accumulation of thermal energy released into the environment. This study introduces a nature-based solution to mitigate the impact of urban overheating by cooling outdoor pavements using water from existing fountains or ponds in cities. The water functions as a coolant, significantly reducing the surface temperature of the pavement by up to 25 °C compared to dry samples exposed to the sun. The innovative aspect of this concept lies in the fact that the pavements do not exhibit capillarity, thereby achieving sensible cooling without evaporation and subsequent water consumption. The concept's impact is examined by considering pavements of varying thicknesses and albedos. In the conducted experiments, water-cooled pavements 100 % eliminated the risk of overheating compared to air temperature. This strategy offers an effective and sustainable approach to counteract the adverse effects of urban overheating in cities.
Diagnóstico de sostenibilidad del rendimiento de centros educativos y desarrollo de herramientas para aumentar las competencias de la comunidad educativa
(Universidad Politécnica de Madrid, 2025) Díaz. José Alberto; Soutullo. Silvia; Giancola, Emanuela; Sánchez. María Nuria; Gamarra, Ana Rosa; Lago, Carmen; Lechón, Yolanda; Marqués-Valderrama, Israel; Chacartegui, Ricardo; Becerra Villanueva, José Antonio; Universidad de Sevilla. Departamento de Ingeniería Energética
El Proyecto ECF4CLIM co-diseña, prueba y valida un marco de competencias europeo para que la comunidad educativa impulse la transición hacia una economía sostenible y baja en carbono, involucrando a centros educativos de diferentes países europeos. En este contexto se analiza el comportamiento energético y medioambiental de cada centro. Este diagnóstico se está llevando a cabo a través de auditorías y herramientas de análisis. Las auditorías se basan en la recopilación de documentación relevante, y en la realización de visitas y encuestas en los diferentes centros educativos, caracterizando la construcción de los edificios, el consumo de energía y agua y otros parámetros ambientales. Las herramientas informáticas permiten calcular la huella ambiental, identificar las estrategias de rehabilitación adaptadas a las condiciones climáticas y evaluar las intervenciones de sostenibilidad. La aplicación combinada de ambas herramientas proporciona las pautas más adecuadas a implantar en cada centro para optimizar su comportamiento.
Improving urban resilience and habitability by an effective regeneration of the streets: A comprehensive approach step-by-step validated in a real case
(Elsevier, 2024-05) Montero Gutiérrez, Paz; Palomo Amores, Teresa Rocío; Guerrero Delgado, María del Carmen; Molina Félix, José Luis; Sánchez Ramos, José; Álvarez Domínguez, Servando; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Ciencia y Tecnología (MCYT). España; Universidad de Sevilla. TEP143: Termotecnia
The world's average temperature has increased by 1 °C, leading to more frequent and intense extreme weather events. Attention has turned to the Urban Heat Island (UHI), a warming phenomenon in cities resulting from human activities and the urban design. In this way, urban adaptation of streets and the development of new urban spaces focus on achieving thermal comfort. While the research community proposed surface energy balances (SEB), a limitation arises from SEB's ability to identify UHI due to its exclusion of anthropogenic heat. This study highlights the need to address anthropogenic variables and the importance of continuous monitoring in urban areas undergoing adaptation. A calculation method called co-simulation is suggested to incorporate anthropogenic heat using ENVI-met software as the basis. Adaptation justification involves monitoring and assessing the COMFA comfort index in an avenue. The calculation process proposes improvements for a comfortable environment, evaluating the microclimate impact on urban adaptation. Implementation, ongoing monitoring, and a comprehensive sensitivity analysis of the COMFA comfort index ensure a 60% improvement in the thermal sensation from June to September. This approach promotes the adoption of innovative solutions for climate change, emphasizing energy efficiency and well-being in urban spaces.
Non-dimensional analysis of PEM fuel cell phenomena by means of AC impedance measurements
(Elsevier, 2011-05) Iranzo Paricio, José Alfredo; Muñoz, Miguel; Pino Lucena, Francisco Javier; Rosa Iglesias, Manuel Felipe; Universidad de Sevilla. Departamento de Ingeniería Energética; Junta de Andalucía
AC impedance or electrochemical impedance spectroscopy (EIS) is becoming a fundamental technique used by researchers and scientists in proton exchange membrane (PEM) fuel cell analysis and development. In this work, in situ impedance measurements are presented for a series of operating conditions in a 50 cm2 fuel cell. The electrode charge transfer resistance was determined from the corresponding arcs of the Nyquist diagrams. The analyses were performed for H2/O2 and H2/air operation at different stoichiometric factors and reactant gases humidification. Characteristic time scales of charge transfer processes at the different operating conditions were estimated from the corresponding Bode plots. These values were used for a non-dimensional analysis of the different fuel cell electrochemical and transport processes, namely electrochemical reaction versus GDL reactant transport. Fuel cell adapted Damkhöler numbers are thus presented, where the results indicate that the GDL diffusion transport is the limiting process for the cases under analysis, especially when air is used as oxidant. Additional analysis of channel convective mass transport versus GDL diffusive mass transport is also presented.
Effects of sodium nitrate concentration on thermophysical properties of solar salts and on the thermal energy storage cost
(Elsevier, 2019) Durth, Melanie; Prieto Rios, Cristina; Rodríguez-Sánchez, Alfonso; Patiño Rodríguez, David; Cabeza. Luisa F.; Universidad de Sevilla. Departamento de Economía e Historia Económica; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Economía y Competitividad (MINECO). España; Generalitat de Catalunya
Thermal energy storage (TES) systems are key components of concentrating solar power plants in order to offer energy dispatchability to adapt the electricity power production to the curve demand. Nitrate molten salts are the storage media used today in concentrated solar power plants. They are also used as heat transfer fluid (HTF) in the molten salt tower (MST) technology. Traditional MST plants work in the temperature range of 240–565 °C using the so-called solar salt, a mixture of 60–40 wt% of NaNO3 and KNO3. This study wants to optimize the thermal energy storage cost of the solar concentration technology by analysing different mixtures of solar salts, using different percentages of NaNO3 and KNO3 in the mixture. The new mixtures seek a reduction in the cost of the storage material while optimizing its physical and chemical properties. The study shows how an increase in the proportion of sodium nitrate for a new binary solar salt to 78–22 wt%, produces an increase in the heat capacity of the mixture by reducing the necessary inventory of salts in the system. However, the new salt presents an increase in the melting point, going from 240 °C to 279 °C, which makes the operation of the system difficult. The impact on the cost of this optimization in the performance of a commercial plant was analysed. The plant chosen to evaluate the impact is a tower technology plant with 85 MWe power and 13 h of storage. The study shows a LCOE reduction of up to 0.6% for the new mixture with higher sodium nitrate.
Liquid water preferential accumulation in channels of PEM fuel cells with multiple serpentine flow fields
(Elsevier, 2014-09) Iranzo Paricio, José Alfredo; Boillat, Pierre; Biesdorf, Johannes; Tapia, Elvira; Salva, Antonio; Guerra Macho, José Julio; Universidad de Sevilla. Departamento de Ingeniería Energética
This work presents an experimental investigation on the preferential accumulation of liquid water in the channels of a multiple serpentine PEMFC with 50 cm2 active area. Neutron imaging was used for visualizing the liquid water distribution during the cell operation for a wide range of operating conditions. Liquid water accumulation in the cathode channels was observed for most of the operating conditions, with a preferential accumulation in certain channels of the flow field. A statistical analysis was performed in order to determine the main characteristics of this accumulation (i.e. channel number and degree of accumulation). As cathode channels were positioned in vertical direction, it was found that gravity effects had an important influence in the accumulation, as well as the relative position of the channel with respect to the inlet and outlet locations. The gas flow direction had also a major impact on the water accumulation within the channels, with significantly more water accumulated in channels with upwards gas flow.
Safety study of a hydrogen leak in a fuel cell vehicle using computational fluid dynamics
(Elsevier, 2012-03) Salva, José Antonio; Tapia, Elvira; Iranzo Paricio, José Alfredo; Pino Lucena, Francisco Javier; Cabrera, Juan; Rosa Iglesias, Manuel Felipe; Universidad de Sevilla. Departamento de Ingeniería Energética
This paper analyzes safety aspects inside a Fuel Cell vehicle using Computational Fluid Dynamics (CFD) tools. The research considers an introduction of a leak of hydrogen inside the vehicle, and its dispersion for a set of typical ventilation conditions is analyzed. The leak of hydrogen has been modelled according to the properties of hydrogen and depending on the pressure difference between the hydrogen storage tank (200 bar) and the atmosphere. The parameters considered for the simulations are the flow rate of cabin ventilation air and hydrogen’s leak. The results obtained for the hydrogen molar concentration are investigated in different sections of the vehicle. Significant differences between front and rear areas are observed, with higher hydrogen concentrations near the rear ventilation vents. The volume of the vehicle within ignition risk (4–75% hydrogen concentration) is also investigated. Finally, different risk mitigation measures are also proposed.
Liquid water distribution patterns featuring back-diffusion transport in a PEM fuel cell with neutron imaging
(Elsevier, 2014-10) Iranzo Paricio, José Alfredo; Boillat, Pierre; Universidad de Sevilla. Departamento de Ingeniería Energética; European Community (EC); Ministerio de Economía y Competitividad (MINECO). España
Back-diffusion in PEM fuel cells is the water transport mechanism contributing to balance the water content profile in the membrane (in the through-plane direction), transporting water molecules from the cathode electrode towards the anode side of the membrane. In this technical note, neutron radiographs are presented for a 50 cm2 N-117 fuel cell with serpentine flow field, where the effect of the back diffusion transport mechanism is clearly identified, in the form of crossed patterns following the cross-flow layout of the flow field. The back diffusion water transport is evident despite the high thickness of the N-117 membrane.
A novel approach coupling neutron imaging and numerical modelling for the analysis of the impact of water on fuel cell performance
(Elsevier, 2014-04-15) Iranzo Paricio, José Alfredo; Boillat, Pierre; Oberholzer, Pierre; Guerra Macho, José Julio; Universidad de Sevilla. Departamento de Ingeniería Energética; Ministerio de Economía y Competitividad (MINECO). España
A novel modelling framework for the simulation of the diffusive mass transport limitations occurring at GDL local scale of PEFCs is presented, in particular in relation with the distribution of liquid water in the porous media. The distinctive characteristic of this framework is the fact that the distribution of liquid water is not predicted by the model but it is instead mapped into the simulation model from available experimental measurements, obtained with neutron imaging. The presence of liquid water is thus included in the model as a modifier for the gas diffusion transport, and not directly calculated by the model. This allows for a coupling of experimental measurements and model development that is expected to allow a further progress of highly reliable models for the understanding of local fuel cell phenomena. A 1D cell is analyzed, and the effective diffusion coefficient and the n exponent in the diffusion correction factor is calculated from the results of the combination of modelling and experimental data. An extension of the method for a 2D cell is also introduced.

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