Examinando por Autor "Rovira de Antonio, Antonio José"

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    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 José
    Solar 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.
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    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, Rubén
    This 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.
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    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, Fernando
    This 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.
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    Analysis of an Integrated Solar Combined Cycle with Recuperative Gas Turbine and Double Recuperative and Double Expansion Propane Cycle.
    (MDPI, 2020) Abbas, Rubén; Sebastián, Andrés; Rovira de Antonio, Antonio José; Muñoz Domínguez, Marta
    The main objective of this paper is to present and analyze an innovative configuration of integrated solar combined cycle (ISCC). As novelties, the plant includes a recuperative gas turbine and the conventional bottoming Rankine cycle is replaced by a recently developed double recuperative double expansion (DRDE) cycle. The configuration results in a fuel saving in the combustion chamber at the expense of a decreased exhaust gas temperature, which is just adequate to feed the DRDE cycle that uses propane as the working fluid. The solar contribution comes from a solar field of parabolic trough collectors, with oil as the heat transfer fluid. The optimum integration point for the solar contribution is addressed. The performance of the proposed ISCC-R-DRDE design conditions and off-design operation was assessed (daily and yearly) at two different locations. All results were compared to those obtained under the same conditions by a conventional ISCC, as well as similar configurations without solar integration. The proposed configuration obtains a lower heat rate on a yearly basis in the studied locations and lower levelized cost of energy (LCOE) than that of the ISCC, which indicates that such a configuration could become a promising technology.
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    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, Fernando
    This 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.
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    Proposal and analysis of an integrated solar combined cycle with partial recuperation.
    (Elsevier, 2020) Abbas, Rubén; Sánchez, Consuelo; Rovira de Antonio, Antonio José; Muñoz Domínguez, Marta
    The paper analyses an integrated solar combined cycle that, as a novelty, includes a gas turbine with partial recuperation. A conventional solar arrangement including parabolic troughs with a thermal oil is assumed. This field feeds a solar steam generator working in parallel with the high-pressure evaporator of the heat recovery steam generator. The plant is designed to balance out the solar supply to the steam cycle with the thermal power transferred to the air in the recuperator before it is introduced in the combustion chamber. Thus, only a fraction of the turbine exhaust gas flows through the recuperator. The additional steam production due to the solar contribution is mitigated by lower power available at the evaporator of the heat recovery steam generator, making possible to achieve constant steam turbine operation regardless the solar contribution. Results show that the proposal reaches better performance and lower generating cost than conventional integrated solar combined cycles. Besides, a new proposal to evaluate plant performances and economical assessments is introduced, which has been shown useful to understand correctly the results obtained.
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    Proposal of a new design of source heat exchanger for the technical feasibility of solar thermal plants coupled to supercritical power cycles
    (Elsevier, 2020-10-12) Linares Hurtado, José Ignacio; Montes Pita, María José::virtual::3123::600; Barbero Fresno, Rubén::virtual::3124::600; Rovira de Antonio, Antonio José::virtual::3125::600; Montes Pita, María José; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José; Montes Pita, María José; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José; Montes Pita, María José; Barbero Fresno, Rubén; Rovira de Antonio, Antonio José
    Solar thermal power plants coupled to supercritical CO2 cycles seems to be a way to increase the global solar-to-electric efficiency. For that, the concentrating solar technology that is best integrated is the molten salt central receiver with a thermal energy storage associated. This work is focused on one of the main challenges of this scheme: the source heat exchanger transferring the thermal energy from the molten salt in the solar field to the CO2 in the power cycle. A new design, based on the printed circuit heat exchanger technology is proposed, that withstands the pressure difference and avoids the molten salt plugging when circulating through microchannels. The thermo-mechanic model of this heat exchanger is also calculated. This work also addresses a thermo-economic optimization of the printed circuit heat exchanger proposed. For that, it is considered the global performance of the solar thermal plant for three layouts: recompression, intercooling and partial-cooling cycles. This optimization yields to a great reduction in the investment cost of these source heat exchangers, achieving the lowest cost in the partial-cooling configuration, followed by the intercooling and finally, the recompression. This trend is also observed in the global performance of the solar plant, so the partial-cooling layout is the one with the lowest levelized cost of electricity; this value is similar to that of the intercooling layout, and both are well below from the cost in the recompression layout, which results the most expensive configuration.
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    Proposal of optimized power cycles for the DEMO power plant (EUROfusion)
    (Elsevier, 2019-11) Sánchez, Consuelo; Rovira de Antonio, Antonio José; Montes Pita, María José; Muñoz Domínguez, Marta
    The objective of this paper is the proposal of two configurations of Rankine cycles different from the standard solution considered for the DEMO 2017 design. The configurations are aimed to maintain as constant as possible the operation at the pulse and dwell modes with minimal fluctuations in the turbine and heat exchangers parameters, in order to maximize the reliability of these components. Each configuration, as well as the reference one, have been simulated both at pulse and dwell operation modes. Compared to the reference design, the proposed configurations are much steadier and mass flow rates in the steam generator and preheaters are constant. In summary, it is possible to ensure a completely steady operation of the whole steam cycle, including all the heat exchangers, without differences between the pulse and dwell modes using two secondary storage tanks additional to the two original molten salt ones.
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    Red de Innovación Docente en Máquinas y Motores Térmicos
    (2009-09) Muñoz Domínguez, Marta; Rovira de Antonio, Antonio José; Margenat Calvo, Sergio
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    Thermodynamic Cycles for Solar Thermal Power Plants: A Review
    (WIREs (Wiley Interdisciplinary Reviews), 2021-10-17) Muñoz Domínguez, Marta; Rovira de Antonio, Antonio José; Montes Pita, María José
    Solar thermal power plants for electricity production include, at least, two main systems: the solar field and the power block. Regarding this last one, the particular thermodynamic cycle layout and the working fluid employed, have a decisive influence in the plant performance. In turn, this selection depends on the solar technology employed. Currently, the steam Rankine cycle is the most widespread and commercially available power block option, usually coupled to a parabolic trough solar field. However, other configurations have been implemented in solar thermal plants worldwide. Most of them are based on other solar technologies coupled to a steam Rankine cycle, although integrated solar Combined cycles have a significant level of implementation. In the first place, power block configurations based on conventional thermodynamic cycles -Rankine, Brayton and combined Brayton-Rankine- are described. The achievements and challenges of each proposal are highlighted, for example, the benefits involved in hybrid solar source/fossil fuel plants. In the second place, proposals of advanced power block configuration are analyzed, standing out: supercritical CO2 Brayton cycles, advanced organic cycles and innovative integrated solar combined cycles. Each of these proposals show some advantages compared to the conventional layouts in certain power or source temperature ranges and hence they could be considered attractive options in the medium term. At last, a brief review of proposals of solar thermal integration with other renewable heat sources is also included.
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    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, Marta
    This 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.
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    Transformaciones homográficas aplicadas a la simulación y optimización del subsistema óptico en centrales termosolares de torre
    (Universidad Nacional de Educación a Distancia (España). Escuela Internacional de Doctorado. Programa de Doctorado en Tecnologías Industriales, 2017-06) Ortega Ruiz, Guillermo; Rovira de Antonio, Antonio José
    Las centrales termosolares de torre, también llamadas sistemas de receptor central, constituyen una de las tecnologías renovables más prometedoras para la producción de electricidad y calor para procesos industriales. Se trata de una tecnología caracterizada por su alto factor de concentración, lo que permite alcanzar mayores temperaturas en el fluido de trabajo y, por este motivo, la posibilidad de alcanzar mayores rendimientos que con otras tecnologías de concentración termosolar más extendidas. El objetivo fundamental de la tesis consiste en la propuesta de una herramienta de simulación y optimización del diseño del subsistema óptico en centrales termosolares de torre, caracterizada por una precisión y exactitud comparables al empleo de una herramienta de trazado de rayos según el método de Monte-Carlo, y presente unos tiempos de computación entre uno y dos órdenes de magnitud inferiores a los obtenidos por la citada técnica. El estudio se desarrolló en varias fases. La primera consistió en analizar y estudiar los principios básicos relacionados con la simulación y optimización del subsistema óptico. Posteriormente, se desarrollaron distintas técnicas enfocadas a la determinación de aquellos rendimientos elementales que suponen un mayor esfuerzo computacional, así como el estudio de aquellas variables que tienen una mayor repercusión en los resultados y tiempos de computación. Por último, se desarrollaron un conjunto de aplicaciones informáticas de simulación y optimización, apoyadas en las técnicas propuestas, las cuales fueron validadas mediante el empleo de técnicas y/o códigos suficientemente contrastados y avalados por la comunidad científica.