Artículos (Ingeniería Energética)

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

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Joint data reconciliation and artificial neural network based modelling: application to a cogeneration power plant
(Elsevier, 2024-01) Vélez Godiño, José Antonio; Jiménez-Espadafor Aguilar, Francisco José; Ingeniería de la Construcción y Proyectos de Ingeniería; Ingeniería Energética; Junta de Andalucía; TEP137: Máquinas y Motores Térmicos; TIC152: Ingeniería de la Construcción y Proyectos de Ingeniería
This contribution represents a practical application of predictive thermal modelling of an existing cogeneration plant. The analysed cogeneration plant consists of a gas turbine coupled to a heat recovery steam generator, which produces two streams of superheated steam (65 bar and 10 bar) and a thermal oil stream at 350 °C. The proposed model was based on an artificial neural network and was trained using real operational data. However, although data acquisition systems currently used in power generation plants allow for the recording of multiple measurements using small sampling intervals, this does not guarantee a satisfactory analysis of operational data. Therefore, the potential of artificial neural networks can result in incorrect or imprecise results if the calibration of the network is performed with inconsistent or highly uncertain datasets. The novelty of this work consisted on the application of data reconciliation to the real dataset before the model training, in order to minimize the typical uncertainty associated with plant instrumentation measurements. The results obtained demonstrated the advantage of training the network with reconciled data and that modelling error is reduced for all analysed outputs when the model is based on artificial neural networks instead of polynomial models.
Investigation of multi-ion heat and neoclassical transport using new edge main ion measurements at ASDEX Upgrade
(IOP Publishing Ltd, 2025-08-21) Cano Megías, Pilar; Viezzer, Eleonora; McDermott, R.M.; Angioni, C.; Jansen van Vuuren, A.; Cavedon, M.; Cruz Zabala, Diego José; Dux, R.; Manas, P.; P.-Gonzalez, J.; Zimmermann, C.F.B.; Chacartegui, Ricardo; Ingeniería Energética; Física Atómica, Molecular y Nuclear; European Union (UE). H2020; EUROfusion Consortium
This study provides new insights into multi-ion heat transport and the validation of neoclassical theory at the edge of H-mode plasmas. Utilizing a high-resolution main ion charge exchange recombination spectroscopy system, the first characterization of edge deuterium temperature (TD) and toroidal velocity (vϕ,D) in a metal wall environment is presented. Dedicated experiments which examine the impact of the heating mix on TD and vϕ,D in the ASDEX Upgrade tokamak are discussed. An unexpected temperature difference between main ions (TD) and impurities (Tz) was discovered when increasing PECRH, TD > Tz. The new temperature measurements have been used to solve the multi-ion heat transport equations with the astra transport code. The interpreted deuterium (χD) and impurity (χz) heat diffusivities have been compared to fluid (tglf) and gyrokinetic (gkw) models. While the dependence of a qualitatively similar χD/χz on the ion to electron heat flux (Qi/Qe) was identified in both experiment and simulation, discrepancies in the absolute value between the two are found when temperature differences between deuterium and impurities are present. The mechanism for the χD/χz dependence on Qi/Qe is the stronger resonant interaction of impurities with low drift frequency turbulence modes in comparison to deuterium. Importantly, it is shown that considering a single ion species (i), and assuming TD = Tz gives reasonable estimates of χD ≈χi for the cases studied here. On the contrary, the evaluation of χz is very sensitive to ion temperature differences, which must be considered for accurate impurity ion heat transport description. Additionally, differences between vϕ,D and vϕ,z were compared to neoclassical calculations. Neoclassical theory can accurately describe vϕ,D (provided an independent measurement of vϕ,z or Er) in the steep gradient region, but not at the pedestal top nor bottom, highlighting the complexity of edge transport phenomena.
Energy analysis of an ultra-low temperature district heating and cooling system with coaxial borehole heat exchangers
(2023-09) Quirosa Jiménez, Gonzalo; Torres-García, Miguel; Becerra Villanueva, José Antonio; Jiménez-Espadafor Aguilar, Francisco José; Chacartegui, Ricardo; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos
The decarbonisation of society requires developing new environmentally friendly solutions for heating and cooling. Ultra-low temperature district heating and cooling (ULTDHC) allows operation with energy sources and systems hard to integrate into previous generations of district networks, making this technology more efficient and sustainable. This work analyses a novel integration of coaxial borehole heat exchangers (CBHEs) to control the temperature of the network, drastically reducing operating costs and emissions compared to existing systems. The concept is analysed based on single and double-loop networks. As a case analysis, it is studied to a ULTDH located in the south of Spain with annual heating and cooling demands of 1045 MWh and 416 MWh, respectively. The single-loop configuration requires more 100 m depth CBHEs connected, 47, whereas the double-loop layout, with a more efficient thermal balance, requires 42. In contrast, it has higher values of annualised costs. The sensitivity analysis of the main parameters proves the system is robust and effective in compensating for external variations. It operates more efficiently in warm/hot regions, increasing the possible applications and implantation expansion. The proposal is useful for new systems and for adapting the existing ones.
Investigation of entropy generation analysis of Gallium alloy based nanofluids in minichannel heat sink
(Elsevier, 2025) Muhammad, Adeel; Allauddin, Usman; Iranzo Paricio, José Alfredo; Ingeniería Energética
In the present study, entropy generation analysis is numerically performed for single-phase laminar flow inside a 3-D minichannel heat sink at Reynolds numbers Re = 300–1900. The influence of different cooling fluids water, GaIn, GaIn nanofluids (GaIn-6 %Alumina, GaIn-6 %CNT, GaIn-6 %Diamond) and substrates (Si silicon, AlN aluminum nitride, Cu copper alloy) on the entropy generation is investigated for a uniform heat flux in a minichannel (M/C). Among GaIn-based nanofluids (N/Fs), GaIn, and water, it is found that GaIn-6 %CNT has the lowest value of total entropy generation per unit length (Sgen,tot) for Cu, AlN, and Si substrates. Besides, when GaIn-6 %CNT serves as a coolant, Si-based M/C offers the highest Sgen,tot = 0.475 Wm-1K−1, at Re = 300, whereas Cu-based M/C has the lowest Sgen,tot = 0.25 Wm-1K−1, at Re = 1900. Among all the materials, Cu has the lowest Sgen,tot, followed by AlN and Si, at all the values of Re for GaIn N/Fs. Besides, the study explores the variation of the Ga alloy nanofluids (GaIn-CNT, GaSn-CNT, EGaIn-CNT, EGaInSn-CNT), volume fractions (φ = 0–10 %), Reynolds numbers (300–1900), and heat fluxes (qb = 100–900 Wcm−2), on the frictional, thermal, total entropy generation, and Bejan number inside the 3-D minichannel. Among Ga alloy nanofluids, it is found that GaInSn-6 %CNT shows the highest total entropy generation, and GaIn-6 %CNT has the lowest Sgen,tot at Re = 300–1900 for qb = 100 Wcm−2. Also, it is observed that the minimum value of Sgen,tot is noted for GaIn-CNT, followed by GaSn-CNT, EGaIn-CNT, and EGaInSn-CNT at all values of concentrations, Re, and AlN substrate.
Schoolyard revegetation as a dual mechanism for environmental education and overheat mitigation
(Elsevier, 2025-06) Serrano Jiménez, Antonio José; Marques Valderrama, Israel; Jiménez Expósito, Rosa Ana; Díaz López, Carmen; Barrios Padura, Ángela; Molina Huelva, Marta; Becerra Villanueva, José Antonio; Chacartegui, Ricardo; Construcciones Arquitectónicas I (ETSA); Estructuras de Edificación e Ingeniería del Terreno; Ingeniería Energética; European Union (UE). H2020; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP206: SATH Sostenibilidad en Arquitectura, Tecnología y Patrimonio: Materialidad y Sistemas Constructivos; TEP137: Máquinas y Motores Térmicos
Current research gaps in environmental action guidelines that tackle urban heat island effects and improve environmental education to students are identified in order to address urban and environmental challenges. This research aims to promote revegetation patterns in schoolyards through a scientific-educational strategy of planting trees, thereby increasing the shaded area and promoting environmental activities in schools in warm climates. This study provides a standardised strategy in five phases for the diagnosis, decision-making, proposal, and monitoring of tree planting, which can be replicated in multiple climatic and urban contexts. This study presents a real-life pilot experience that tests and applies this strategy in Itaca secondary school, in Southern Spain, within an H2020-European research project, in which a diagnosis of the schoolyard and an in-situ tree-planting strategy is developed by researchers together with students. The collaborative methodology is based on a multidisciplinary evaluation involving a selection of tree species and their in-situ planting by the students, thereby filling the gap with an action strategy towards greener practices in schools and highlighting key outcomes for upcoming bioclimatic policies. The results confirm an increase in the Normalised Difference Vegetation Index (NDVI) from 0.15 to 0.74 in tree-planting areas, and 91.5% of the 142 participants in the educational community have perceived this tree-planting strategy as highly satisfactory for increasing outdoor comfort. The conclusions reveal multiple insights that contribute to sustainable development goals, based on the environmental education between researchers and students and on the advantages in mitigating the effects of overheating in schoolyards.
Control smartness of a smart control system coupled with inertial thermal system: defining the future frontiers through an experimental analysis
(Elsevier, 2025) Monge Palma, Rafael; Castro Medina, Daniel; Sánchez Ramos, José; Guerrero Delgado, María del Carmen; Pagliano, Lorenzo; Erba, Silvia; Álvarez Domínguez, Servando; Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Defining a control solution for the building energy system is a task that has continuously been exploited by researchers over the years. Different control approaches can introduce advanced functionalities in building energy systems. However, it remains unclear how suitable each technique is for different levels of control complexity. A field experiment was conducted using a radiant floor system in a fully monitored test room to assess the control quality of both an analogue and a commercial smart control system across two different heat pumps. The key novelty of this work lies in the field assessment of the “smartness” level of a commercial smart control solution, introducing a methodology for evaluating the effective control quality decisions in building energy systems, particularly in HVAC systems. The study found that a “smart” controller, solely focused on precise indoor temperature control, did not guarantee energy savings and potentially jeopardized equipment due to frequent cycling. This highlights the lack of a clear definition for “smart” controllers, leading to the mislabelling of commercially available systems that often rely on basic control strategies. Furthermore, the study revealed that the heat pumps under investigation performed significantly lower than manufacturer specifications, operating at up to 30% lower efficiency under high thermal loads. Surprisingly, efficiency decreased instead of increasing at part load, contradicting both literature and manufacturer claims. This discrepancy poses challenges to the reliability of declared equipment’s performance by manufacturers.
Critical Assessment of Migration Strategies for Corrosion in Molten Salts
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Pavón Moreno, María del Carmen; López-Paneque, Antonio Manuel; Gallardo Fuentes, José María; Paúl Escolano, Antonio; Díaz Gutiérrez, Eduardo; Prieto Ríos, Cristina; Ingeniería Energética; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This review article examines the corrosion phenomena and mitigation strategies associated with molten salts used in thermal energy storage (TES) and heat transfer applications. Corrosion presents a critical challenge in concentrated solar power (CSP) plants and other high-temperature systems, affecting the durability and cost-efficiency of materials in storage tanks, heat exchangers, and piping. This study offers a comprehensive comparison of corrosion test methods and results, analyzing factors such as operating conditions, salt compositions, and material properties. Emphasis is also placed on strategies such as molten salt purification, the addition of corrosion inhibitors, and the application of protective coatings. This review aims to advance research and development in the TES sector by highlighting knowledge gaps and proposing directions for future experimentation.
Gasification of Agricultural Biomass Residues for Sustainable Development of Mediterranean Europe Regions: Modelling and Simulation in Aspen Plus
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) López García, Elisa; Rodríguez Pastor, Diego Antonio; Chacartegui, Ricardo; Rouboa, Abel; Monteiro, Eliseu; Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
The utilisation of agricultural residues for power generation is an opportunity to reduce fossil fuel usage and foster a sustainable circular economy in Mediterranean European regions. This can be achieved by resorting to the gasification process, which faces challenges such as optimising its operation parameters on real-world applications and lowering operational costs. This work studies the gasification process of a set of agricultural biomasses widely available in the Mediterranean Europe regions through modelling and simulation in Aspen Plus. The selected biomasses are olive stone, grapevine waste, and wheat straw. The effect of temperature, equivalence ratio, and steam-to-biomass ratio on gasifier performance and their effect on gas composition was assessed. The results indicate that olive stone and wheat straw performed best in terms of syngas composition and cold gas efficiency. The analyses show good gasification performance for temperatures above 750 °C, equivalence ratios ranging from 0.1 to 0.3, depending on the raw material and steam-to-biomass ratios below 0.1. The obtained values show the validity and the potential of a downdraft gasification reactor to be used with these abundant agricultural biomasses in the Mediterranean European region. Its integration with a reciprocating engine is a rational choice for distributed power generation.
Experimental observations of fast-ion losses induced by neoclassical tearing modes in the MAST-U spherical tokamak
(IOP Publishing, 2025-04) Rivero Rodríguez, Juan Francisco; Velarde Gallardo, Lina; Williams, T.; Galdón Quiroga, Joaquín; García Muñoz, Manuel; Rueda Rueda, José; Viezzer, Eleonora; MAST Upgrade Team; Eurofus Tokamak Exploitat Team; Ingeniería Energética; Física Atómica, Molecular y Nuclear; European Union (UE); Engineering and Physical Sciences Research Council (UK)
Neoclassical tearing modes (NTMs) have been identified as the most deleterious perturbations in high-performance plasmas at Mega Amp Spherical Tokamak Upgrade (MAST-U). They produce magnetic islands that flatten the electron temperature profile and enhance the fast-ion transport. Understanding the NTM-induced losses can reveal paths to mitigate them, thus increasing the energy available to heat up the plasma. The MAST-U fast-ion loss detector (FILD) is equipped with a high-resolution camera and a high-speed camera that simultaneously measure the fast-ion losses in MAST-U. The combination of both systems makes it possible to infer the velocity-space of the losses fluctuating at the frequency of the NTMs. The FILDSIM code is used to infer the velocity space of the fast-ion losses from the strike position in a scintillator plate. Eulerian video magnification is employed to identify the losses that oscillate at the frequencies of the NTMs. NTMs produce fast-ion losses across a broad range of velocity space, with pitch angles ranging from 35∘ to 54∘. Non-linear interactions between the fast-ion orbits and different magnetic islands have been observed. The lost fast-ion orbits meet the stringent conditions that makes it possible to measure these effects.
Validation of PCHE-Type CO2–CO2 Recuperative Heat Exchanger Modeling Using Conductance Ratio Method
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Illyés, Viktoria Carmen; Crespi, Francesco Maria; Guerif, Xavier; Werner, Andreas; Ingeniería Energética; European Union
Printed-circuit heat exchangers (PCHEs) are compact exchangers with exceptional heat-transfer properties that are important for supercritical CO2 technology. Recalculating the heat transfer under off-design conditions is a common task. Thus, in this paper, traditional and PCHE-specific correlations are analyzed in a conventional, discretized one-dimensional model using the conductance ratio method. The predicted heat transfer is compared with the experimental data of a CO2–CO2 heat exchanger with zigzag-type channels and one with s-shaped fin channels under various working conditions. The results demonstrate that all selected heat-transfer correlations predicted the transferred heat within +/−20% using the conventional model. The much simpler conductance ratio method yields better results, with heat transfer within +/−10%, even with conservative inputs to the model.
Scenarios for Energy Recovery from Slaughterhouse Wastes in Europe
(Elsevier, 2025) Guisado Falante, José Manuel; Becerra Villanueva, José Antonio; Chacartegui, Ricardo; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos
This work evaluates the potential for slaughterhouse industry waste conversion into raw energy products in the European Union. On this objective, it develops a theoretical model of energy consumption and availability as a function of waste quality, validated with real data. It is used to study the valorization potential of these wastes in Europe at the country level by conducting a logical and specialized classification of the waste generated. Three scenarios are considered depending on the pathway for the valorization of products. The optimal scenario predicts a net energy capacity at the EU up to 7152 kWh/tonne. It corresponds to an additional annual net energy production capacity at the European Union of almost 50000 million kWh with an increase in waste energy recovery of 48%. The maximum potential capacity is identified in Spain which has the potential to produce 7000 million kWh/year or Denmark, which could produce 293 kWh/year per capita.
Modeling of an innovative integration of compressed air energy storage (CAES) with high-temperature concentrated solar power (CSP): A comprehensive use-case study
(Elsevier, 2025-10) Baigorri, Javier; Federici, Alessandro; Kubikova, Tereza; Du Toit, Theunis; Rodríguez de Arriba, Pablo Enrique; Salvini, Coriolano; Sánchez Martínez, David Tomás; Zaversky, Fritz; Ingeniería Energética; European Union
The transition to a sustainable energy future requires advanced solutions to address the intermittency of renewable energy sources. This study evaluates a novel integration of a high-temperature air-based Concentrated Solar Power (CSP) plant with Compressed Air Energy Storage (CAES), aiming to develop a high-efficiency and zero-emission energy storage system that can also provide inertia to the electrical grid. The concept is demonstrated through a comprehensive system-level model developed to simulate the 24-h operation of a reference case, focusing on the design and off-design performance of key components, including the compression/expansion trains, heat exchangers, and packed-bed Thermal Energy Storage (TES). Furthermore, coupling the plant with an Organic Rankine Cycle (ORC) bottoming cycle and waste heat recovery for industrial applications significantly improves overall efficiency. The concept enables the compression train to operate at lower pressure ratios than adiabatic CAES while operating the expansion train at a high temperature, as the necessary heat is supplied by the solar field, utilizing cost-effective, commercially available equipment. A novel heat exchanger design, inspired by heat recovery steam generators, efficiently integrates atmospheric air from the TES with pressurized air from CAES. Key findings include achieving a Round-Trip Efficiency (RTE) of 43.1 % and an electricity production-to-consumption ratio of 107.8 %, owing to the combined contributions of grid-stored electricity and dispatchable electricity production from solar energy. A comparative analysis of constant pressure versus sliding pressure operation in the expansion train further enhances efficiency. These results position the CAES-CSP concept as a promising solution, and future work will include economic evaluation and optimization to build on these findings.
Enhancing citizen climate resilience identification: A customization methodology to tailor comfort metrics to individual preferences
(Elsevier, 2025) Palomo Amores, Teresa Rocío; Guerrero Delgado, María del Carmen; Sánchez Ramos, José; Castro Medina, Daniel; Montero Gutiérrez, Paz; Álvarez Domínguez, Servando; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; TEP143: Termotecnia
Occupants' adaptability varies based on the climate. Therefore, adaptation measures should be adapted not only to suit the climate but also to the occupants. A holistic methodology is proposed to customise comfort index by adjusting them to the specific preferences of the occupants. The methodology involves collecting subjective and objective data. A measurement procedure is designed to gather comprehensive information, including a low-cost effective procedure to disaggregate the Mean Radiant Temperature between long and short-wavelength effects, essential for outdoor comfort. This customisation is applied to the COMFA index in different real cases. The results show that children in relaxed environments demonstrate 50 % higher resilience than the standard scale, while adults can tolerate 30 % higher thermal loads than the standard when resting. Furthermore, under identical circumstances, children exhibit 8 % greater resilience than adults. Conversely, radiant exchange decomposition indicates that a 30 % augmentation in the short wavelength effect is associated with a 45 % increase in the occupant's thermal load. This methodology facilitates the identification of measures to achieve optimal levels of comfort adapted to the occupants in any climate and area under study. It also contributes to the promotion of urban design and planning that enhances the resilience of citizens.
Exploring a new approach to ancient Qanat techniques using earth-air and water-air heat exchangers for efficient natural cooling
(Elsevier, 2025) Montero Gutiérrez, Paz; Sánchez Ramos, José; Castro Medina, Daniel; Palomo Amores, Teresa Rocío; Guerrero Delgado, María del Carmen; Álvarez Domínguez, Servando; Ingeniería Energética; European Commission (EC); Ministerio de Ciencia, Innovación y Universidades (MICIU). España; TEP143: Termotecnia
The growing demand for sustainable climate adaptation in cities has intensified interest in passive, energy-efficient cooling systems, especially for semi-open public spaces where conventional air-conditioning solutions are often inefficient. This study proposes a novel reinterpretation of the Persian Qanat system, integrating it with contemporary engineering through Earth-Air and Water-Air Heat Exchangers to create nature-based infrastructure for urban cooling. The experimental set-up is installed at full scale in a public space and includes buried ducts interacting with the soil and submerged ducts connected to a water reservoir named Qanat. The system operates in two phases: daytime cooling by passive heat exchange and nighttime regeneration using evaporative and radiative cooling to restore thermal capacity. Performance was assessed through continuous environmental monitoring, including air, soil and water temperatures, and cooling energy calculations. The results indicate air temperature reductions of up to 8 °C between the inlet and outlet of the ducts during the hottest hours of the day. At night, evaporative regeneration reduced the soil temperature to 23 °C, improving the cooling potential for the following day. The energy analysis showed daily cooling values reaching up to 19 kWh. These findings confirm the potential of the system as a scalable and sustainable climate solution, enhancing thermal comfort in urban environments while recovering ancestral techniques adapted through modern design.
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.

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