Usual size of parabolic trough solar thermal plants being built at present is approximately 50 MW e . Most of these plants do not have a thermal storage system for maintaining the power block performance at nominal conditions during long non-insolation periods. Because of that, a proper solar field size, with respect to the electric nominal power, is a fundamental choice. A too large field will be partially useless under high solar irradiance valúes whereas a small field will mainly make the power block to work at part-load conditions. This paper presents an economic optimization of the solar múltiple for a solar-only parabolic trough plant, using neither hybridization ñor thermal storage. Five parabolic trough plants have been considered, with the same parameters in the power block but different solar field sizes. Thermal performance for each solar power plant has been featured, both at nominal and part-load conditions. This characterization has been applied to perform a simulation in order to calcúlate the annual electricity produced by each of these plants. Once annual electric energy generation is known, levelized cost of energy (LCOE) for each plant is calculated, yielding a minimum LCOE valué for a certain solar múltiple valué within the range considered.

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This paper describes the influence of the solar múltiple on the annual performance of parabolic trough solar thermal power plants with direct steam generation (DSG). The reference system selected is a 50 MW e DSG power plant, with thermal storage and auxiliary natural gas-fired boiler. It is considered that both systems are necessary for an optimum coupling to the electricity grid. Although thermal storage is an opening issue for DSG technology, it gives an additional degree of freedom for plant performance optimization. Fossil hybridization is also a key element if a reliable electricity production must be guaranteed for a defined time span. Once the yearly parameters of the solar power plant are calculated, the economic analysis is performed, assessing the efíect of the solar múltiple in the levelized cost of electricity, as well as in the annual natural gas consumption.

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A Micromegas detector was used in the neutron Time-Of-Flight ðn TOFÞ facility at CERN to evaluate the spatial distribution of the neutron beam as a function of its kinetic energy. This was achieved over a large range of neutron energies by using two complementary processes: at low energy by capture of a neutron via the 6 Liðn; aÞt reaction, and at high energy by elastic scattering of neutrons on gas nuclei (argon+isobutane or helium+isobutane). Data are compared to Monte Carlo simulations and an analytic function fitting the beam profile has been calculated with a sufficient precision to use in neutron capture experiments at the n TOF facility. r

The study of the performance of an innovative receiver for linear Fresnel reflectors is carried out in this paper, and the results are analyzed with a physics perspective of the process. The receiver consists of a bundle of tubes parallel to the mirror arrays, resulting on a smaller cross section for the same receiver width as the number of tubes increases, due to the diminution of their diameter. This implies higher heat carrier fluid speeds, and thus, a more effective heat transfer process, although it conveys higher pumping power as well. Mass flow is optimized for different tubes diameters, different impinging radiation intensities and different fluid inlet temperatures. It is found that the best receiver design, namely the tubes diameter that maximizes the exergetic efficiency for given working conditions, is similar for the cases studied. There is a range of tubes diameters that imply similar efficiencies, which can drive to capital cost reduction thanks to the flexibility of design. In addition, the length of the receiver is also optimized, and it is observed that the optimal length is similar for the working conditions considered. As a result of this study, it is found that this innovative receiver provides an optimum design for the whole day, even though impinging radiation intensity varies notably. Thermal features of this type of receiver could be the base of a new generation of concentrated solar power plants with a great potential for cost reduction, because of the simplicity of the system and the lower weigh of the components, plus the flexibility of using the receiver tubes for different streams of the heat carrier fluid.

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