Persona: Barbero Fresno, Rubén
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rbarbero@ind.uned.es
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0000-0002-6033-1309
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Barbero Fresno
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Rubén
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Publicación A new design of multi-tube receiver for Fresnel technology to increase the thermal performance(Elsevier, 2022-03-05) Abbas, Rubén; Montes Pita, María José; Barbero Fresno, Rubén; Rovira de Antonio, Antonio JoséSolar heat for industrial processes is a promising way to meet the high thermal demand required by the industry, while this application becomes an important niche market for solar technology. In this research line, it is proposed a novelty concept based on a rotary Fresnel solar collector to supply heat above 150 °C. This work is focused on the multi-tube receiver for this Fresnel collector, proposing a thermal design based on three criteria that can be generalized for any multi-tube receiver: the fluid flow layout is arranged to meet the symmetry of the solar flux map; the fluid circulates from the lower to the higher flux density zone; and the fluid velocity is modified by modifying the tube diameter, to optimize the heat transfer. Following these criteria, the final configuration of the receiver is chosen based on an exergy optimization, in which both heat loss and pressure drop must be quantified. It has been also accomplished a generalization of the optimization methodology for Fresnel collectors providing heat at different temperatures, showing that, in these cases, the configuration that maximizes the exergy efficiency does not correspond to the one with the highest energy efficiency. This thermal design method can be applied to multi-tube receivers working at higher temperatures in longer Fresnel loops, in which case the optimization will result in more marked differences between the optimal values and the standard ones.Publicación Optimization of a New Design of Molten Salt-to-CO2 Heat Exchanger using Exergy Destruction Minimization(MDPI, 2020-08-08) Linares Hurtado, José Ignacio; Moratilla, Beatriz Yolanda; Montes Pita, María José; Barbero Fresno, RubénOne of the ways to make cost-competitive electricity, from concentrated solar thermal energy, is increasing the thermoelectric conversion efficiency. To achieve this objective, the most promising scheme is a molten salt central receiver, coupled to a supercritical carbon dioxide cycle. A key element to be developed in this scheme is the molten salt-to-CO2 heat exchanger. This paper presents a heat exchanger design that avoids the molten salt plugging and the mechanical stress due to the high pressure of the CO2, while improving the heat transfer of the supercritical phase, due to its compactness with a high heat transfer area. This design is based on a honeycomb-like configuration, in which a thermal unit consists of a circular channel for the molten salt surrounded by six smaller trapezoidal ducts for the CO2. Further, an optimization based on the exergy destruction minimization has been accomplished, obtained the best working conditions of this heat exchanger: a temperature approach of 50 °C between both streams and a CO2 pressure drop of 2.7 bar.Publicación Intelligence-based prediction of coefficient of performance for a novel high-temperature industrial heat pump: Comparative performance of ANN and ANFIS models(Elsevier, 2026-02-02) Golpour, Iman; Marcos del Cano, José Daniel; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José; Butean, Alex; Høeg, Arne; Comisión EuropeaThis study presents a comparative evaluation of the artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) approaches for predicting the coefficient of performance (COP) of the HoegTemp, a high-temperature heat pump (HTHP) based on a Stirling cycle (SC) with a design heat capacity of 400 kW. Experimental tests were conducted at the IVAR biogas facility in Stavanger, Norway. This study employed a feedforward backpropagation neural network (FFBPNN) model with one and two hidden layers, with various numbers of neurons and three activation functions, as well as the ANFIS approach, to estimate the COP of the SC-HTHP. The FFBPNN model used the Levenberg-Marquardt (LM) and Bayesian regularization (BR) training algorithms, while the ANFIS model utilized a hybrid optimization method and grid partitioning. The ANN and ANFIS models were evaluated using the following input variables: temperature ratio (1.4–1.6 K/K), average source temperature (21–22 °C), average sink temperature (139–199 °C) and hot water inlet temperature (137–197 °C), with COP as the output variable. The results demonstrated that the FFBP-ANN model exhibited superior predictive accuracy compared to the ANFIS model, achieving R2 = 0.9999, MSE = 0.00010, MAE = 0.00804, and RMSE = 0.01000, whereas the ANFIS approach resulted in R2 = 0.9863, MSE = 0.00019, MAE = 0.01114, and RMSE = 0.01392. The optimal ANN topology was 4–23-16–1 with tansig–logsig–purelin activation functions. In contrast, the best membership functions selected for ANFIS were Gaussian for the input layer and constant for the output layer.Publicación Towards high solar contribution in hybrid CSP-combined cycle gas turbine plants(Hindawi, 2023) Ortega, Guillermo; Rovira de Antonio, Antonio José; Barbero Fresno, Rubén; Subires Tejedor, Antonio Jesús; Muñoz Domínguez, MartaThis paper proposes and analyses several configurations for hybridising concentrating solar power (CSP) plants with combined cycle gas turbines (CCGT). The objective is to increase the solar contribution to a large extent, much higher than those obtained in integrated solar combined cycles but maintaining synergies, which are usually lost when increasing the solar share. For that, two thermal energy management systems are introduced at different temperature levels. First, a configuration with only the low-temperature system is proposed. Then, an enhanced configuration with the low- and high-temperature systems is conceived. These configurations are compared to reference CSP and CCGT state-of-the-art plants. The analyses include different strategies of operation and two sizes for the thermal energy storage system. The results show that the first proposed configuration introduces some synergies but cannot improve the performance of the reference CSP and CCGT working separately, due to an issue with the solar dumping on days with high solar irradiation. The enhanced configuration overcomes this problem and maintains the synergies, leading to an improvement from both the thermodynamic and economic points of view, increasing the solar contribution and decreasing the levelized cost of energy over the reference plants.Publicación Comparison of Different Technologies for Integrated Solar Combined Cycles: Analysis of Concentrating Technology and Solar Integration(MDPI, 2018-04-25) Sánchez, Consuelo; Abbas, Rubén; Muñoz Antón, Javier; Ortega, Guillermo; Rovira de Antonio, Antonio José; Valdés Fernández, Manuel Tomás; Barbero Fresno, Rubén; Montes Pita, María José; Muñoz Domínguez, Marta; Varela Díez, FernandoThis paper compares the annual performance of Integrated Solar Combined Cycles (ISCCs) using different solar concentration technologies: parabolic trough collectors (PTC), linear Fresnel reflectors (LFR) and central tower receiver (CT). Each solar technology (i.e. PTC, LFR and CT) is proposed to integrate solar energy into the combined cycle in two different ways. The first one is based on the use of solar energy to evaporate water of the steam cycle by means of direct steam generation (DSG), increasing the steam production of the high pressure level of the steam generator. The other one is based on the use of solar energy to preheat the pressurized air at the exit of the gas turbine compressor before it is introduced in the combustion chamber, reducing the fuel consumption. Results show that ISCC with DSG increases the yearly production while solar air heating reduces it due to the incremental pressure drop. However, air heating allows significantly higher solar-to-electricity efficiencies and lower heat rates. Regarding the solar technologies, PTC provides the best thermal results.Publicación Decarbonizing European industry: a novel technology to heat supply using waste and renewable energy(MDPI, 2024-10-06) Marcos del Cano, José Daniel; Golpour, Iman; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José; Comisión EuropeaThis study examines the potential for the smart integration of waste and renewable energy sources to supply industrial heat at temperatures between 150 °C and 250 °C, aiming to decarbonize heat demand in European industry. This work is part of a European project (SUSHEAT) which focuses on developing a novel technology that integrates several innovative components: a Stirling cycle high-temperature heat pump (HTHP), a bio-inspired phase change material (PCM) thermal energy storage (TES) system, and a control and integration twin (CIT) system based on smart decision-making algorithms. The objective is to develop highly efficient industrial heat upgrading systems for industrial applications using renewable energy sources and waste heat recovery. To achieve this, the specific heat requirements of different European industries were analyzed. The findings indicate that industrial sectors such as food and beverages, plastics, desalination, textiles, ceramics, pulp and paper, wood products, canned food, agricultural products, mining, and chemicals, typically require process heat at temperatures below 250 °C under conditions well within the range of the SUSHEAT system. Moreover, two case studies, namely the Pelagia and Mandrekas companies, were conducted to validate the effectiveness of the system. An analysis of the annual European heat demand by sector and temperature demonstrated that the theoretical potential heat demand that could be met by the SUSHEAT system is 134.92 TWh annually. Furthermore, an environmental impact assessment estimated an annual significant reduction of 19.40 million tonnes of CO2 emissions. These findings underscore the significant potential of the SUSHEAT system to contribute to the decarbonization of European industry by efficiently meeting heat demand and substantially reducing carbon emissions.Publicación Steady-state analysis of an innovative rotatory Fresnel collector integrated into two industrial processes(Elsevier, 2025-04-01) Ibarra Mollá, Mercedes; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José; https://orcid.org/0000-0001-9859-2435; https://orcid.org/0000-0002-6033-1309; https://orcid.org/0000-0002-6810-3757This study compares the performance of two solar thermal systems, MAND and AMTP, designed for industrial process heat using a rotating Fresnel collector (Sundial) and Phase Change Material (PCM) thermal energy storage (TES). The systems differ in their latitude and in their demand profiles: MAND, located at low latitude, has a continuous 24-hour demand, while AMTP, located at high latitude, has a daytime-only demand. Through steady-state simulations, both daily and yearly performance were analyzed to assess the impact of these differences on system behavior. The designed system achieved annual energy outputs of 26,34 MWh and 25,37 MWh for the two case studies, over the prescribed target of 25 MWh and capacity factors of 30,34% and 32,11%. Results demonstrate that TES plays distinct roles in each system, with carryover storage being crucial for MAND and maximizing heat exchanger operation being more important for AMTP. The analysis highlights the importance of tailoring system design and control strategies to specific industrial process requirements and demonstrated the feasibility of integrating the ASTEP system for industrial applications, even with not favorable conditions like high latitude and daytime-only demand.Publicación Desarrollo de un modelo teórico para la caracterización del rendimiento térmico en colectores solares. Aplicación a tecnologías de generación eléctrica(Universidad Nacional de Educación a Distancia (España). Escuela Internacional de Doctorado. Programa de Doctorado en Tecnologías Industriales, 2018-07-05) Barbero Fresno, Rubén; Montes Pita, María José; Rovira de Antonio, Antonio JoséLa necesidad de aumentar la contribución de las energías renovables en las matrices de generación eléctrica y la consideración de determinados aspectos técnicos auguran una importante contribución de las plantas termosolares, según los escenarios previstos por los distintos agentes involucrados en el sector. En la actualidad, las distintas tecnologías termosolares están experimentando importantes reducciones de coste y mejoras en su rendimiento, pero todavía se necesitan esfuerzos adicionales para competir con otras tecnologías, como el caso de plantas de generación eólica o fotovoltaica. Esta tesis tiene como objetivo contribuir a la I+D+i en el diseño de receptores solares, de modo que se pueda facilitar la tarea de mejora de su rendimiento. Para ello se plantea el desarrollo de un nuevo modelo analítico que permita el cálculo del rendimiento térmico. Dicho modelo reduce las limitaciones que presentan los desarrollados hasta la fecha. Del modelo principal desarrollado se derivan una serie de expresiones simplificadas, de modo que forman un cuerpo de modelos en el que cada una de las expresiones tiene un rango de aplicación acotado. Este cuerpo de modelos presenta una serie de diferencias con respecto a los modelos existentes en la actualidad: permite el cálculo del rendimiento de manera explícita en amplios rangos de operación y con precisión adecuada; contempla, en todas sus expresiones, la influencia de los parámetros de los que depende y habilita el estudio de tendencias en amplios rangos de operación, facilitando el desarrollo de nuevos diseños de mayor rendimiento.Publicación Analysis and comparison of Integrated Solar Combined Cycles using parabolic troughs and linear Fresnel reflectors as concentrating systems(Elsevier, 2015-11-12) Abbas, Rubén; Rovira de Antonio, Antonio José; Barbero Fresno, Rubén; Montes Pita, María José; Varela Díez, FernandoThis paper compares the annual performance and economic feasibility of Integrated Solar Combined Cycles (ISCC) using two solar concentration technologies: parabolic trough collectors (PTC) and linear Fresnel reflectors (LFR). Integration of solar energy to the steam turbine of a combined cycle gives some advantages: the first one is the fuel saving due to the solar contribution and, additionally, the second one is that this contribution takes place especially in highly insolated periods with high ambient temperatures, when conventional combined cycles decrease their power rate and work with decreased efficiency. Previous works showed the convenience of ISCC using PTC and direct steam generation in locations with severe climatology. Besides, LFR technology is currently considered as a good option for reducing the cost of concentrating solar power. Thus, in the present work both concentrating technologies are studied and compared. Solar contribution is only used for evaporating water, increasing the production of the high pressure level of the steam generator. Two locations, Almeria and Las Vegas, are selected for the annual analyses. Results show that the proposed evaporative configurations increase the annual performance. Also, the thermal contribution is higher with PTC, but LFR may improve the economic feasibility of the plant.Publicación Advanced thermodynamic cycles for finite heat sources: proposals for closed and open heat sources applications(Elsevier, 2020) Sánchez, Consuelo; Rovira de Antonio, Antonio José; Muñoz Domínguez, Marta; Barbero Fresno, RubénThis paper analyses two non-conventional thermodynamic cycles designed to work with finite heat sources, which are suitable for maximum temperatures of about 400 °C. The Hybrid Rankine-Brayton (HRB) cycle fits well to closed heat sources and, in the paper, it is analysed considering its exergy efficiency and some requirements for the maximum and minimum temperature of the heat transfer fluid that feeds the cycle, obtaining promising results. The other one is a new proposal called Recuperated and Double Expanded (RDE) cycle, aimed to translate the good features of HRB from closed heat sources to open ones, where the performance of HRB is limited. Both cycles are compared to some reference ones. Results show that the HRB cycle is a good candidate for finite closed heat sources, particularly with maximum temperature around 400 °C and with temperature changes of the heat transfer fluid from 100 °C to 150 °C. The RDE cycle exhibits good performance for finite open heat sources with maximum temperatures between 200 °C and 400 °C, and it behaves similarly to tri-lateral cycles.