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This work proposes a new particle receiver for Concentrating Solar Technology (CST) that employs air and particles as heat transfer fluid (HTF). The novel Linear Particle Solar Receiver (LPSR) is located at the ground level receiving the concentrated solar energy linearly from the top. This receiver is formed by several fluidized beds connected consecutively allowing the horizontal movement of solids and the linear absorption of solar energy. A new solar field is proposed and analyzed to redirect the concentrated solar energy towards the receiver linearly. The optic analysis of a linear beam-down system is carried out using a ray-tracing software. Then, the performance of a linear particle solar receiver is analyzed considering target temperatures of 200 °C, 400 °C, 600 °C and 800 °C to reproduce CST integration with medium and high temperature process heat, Rankine power generation and supercritical CO2 (sCO2) cycles, respectively. The temperature of the hot streams of air and sand are calculated considering the heat losses from the receiver and the compressor parasitic consumption. The procedure to determine the optimum design is shown studying one line as a function of the target temperature. For instance, a sand mass flow of 1.75 kg/s in a receiver of 0.5 m width and a secondary reflector eccentricity of 0.8, can be heated up to 600 °C in a length of 280 m, showing a solar field efficiency of 40.25% and a receiver thermal efficiency of 80%. This work has been supported by the Spanish Government under the project ENE2015-69486-R (MINECO/FEDER, UE), by "Comunidad de Madrid" and European Structural Funds under the project ACES2030-CM project (S2018/EMT-4319) and by the fellowship "Ayuda a la investigación en energía y medio ambiente" of Fundación Iberdrola España.

Meagre is a relatively new aquaculture species with great potential in large scale European aquaculture. The primary objective of the study was to describe, for the first time, parentage allocation and assign offspring to their parents for an industrial scale production system. A total of 800 meagre fish were sampled from two large cages in January and May 2016, both part of a commercial farm site in Valencia, Spain. All fish originated from the same spawning event obtained from a broodstock of 6 females and 13 males. However, due to differential growth during the juvenile stage the fish were graded into two groups, a group of larger juveniles that was transferred to one cage (batch 1) and a group of smaller juveniles that were transferred to the second cage (batch 2). Total length and weight was measured for all fish that were genotyped with a 10 microsatellite loci multiplex to infer parentage based on parental genotypes. Parentage assignment rate was high (87.5% for batch 1 and 95% for batch 2) and provided evidence that offspring belonged to 20 families. Half of the broodstock was identified as probable parents of the offspring (five females and seven males).Between the two sea-cages, a slight differential composition for the same families was encountered. The fifteen shared families that the offspring were assigned to, were analyzed for statistical significant differences concerning body weight and total body length, differences which were observed in 3 families for both batches. We estimated the heritability for body weight and total body length, as well as the genetic and phenotypic correlations for these two traits. Batch 1 showed higher heritability estimates than batch 2 with the genetic and phenotypic correlation estimates being almost the same for both batches. Certain parents contributed more offspring and exhibited dominance in spawning. Similarly, the growth related traits of body weight and total body length of the dominant parents correlate, putatively, with the statistical important differences that are observed in these three families. info:eu-repo/semantics/acceptedVersion

Solar tower plants are pushed to operate with fast start-ups and/or load changes to increase their dispatchability and competitiveness. However, this operation mode decreases the lifetime on components like the steam generator due to fatigue damage. Moreover, the high operating temperatures typical of solar tower plants also lead to creep damage, which it is combined with fatigue. Both damage mechanisms may lead to a dramatic reduction of the steam generator lifetime, compromising the power plant economic viability. In this work the lifetime of the steam generator of a solar tower plant is investigated. For that purpose, an elastic-plastic approach is used to consider the material cyclic hardening. The results show that the steam generator formed by shell-and-tube heat exchangers can operate during 25 years with temperature change rates up to 150 degrees C/h, assuming 300 start-ups per year. The most critical point is the superheater head-nozzle junction for both intermittent and continuous operation regimes. An optimization of the superheater head thickness is performed to maximize its lifetime in both regimes. Finally, it can be concluded that temperature change rates higher than 150 degrees C/h may require a different design of the superheater head and/or a material with better creep-fatigue properties

Solar tower plants (STP) are one of the most promising renewable technologies to substitute conventional power plants. To further increase its penetration in electricity markets, it is necessary to maximize its efficiency. This work addresses the challenge of increasing the inlet pressure up to 165 bar at the high pressure turbine (HPT) to improve the power block efficiency. Nowadays, these plants operate Rankine cycle with reheating using steam at 126 bar at the inlet of the HPT. This pressure is limited in current STP by the working temperatures of the molten salt, which range from 285 degrees C and 565 degrees C, the pinch point temperature difference in the evaporator and the current steam generator (SG) layout. A new steam generator design with dual-pressure level evaporation is proposed. The heat exchangers that form the SG are designed thermomechanically and the power cycle performance is analyzed using the first and second laws of thermodynamics. The results show that the novel dual-pressure level SG layout increases the power block efficiency from 44.14% to 44.64%. Assuming a market pricing scenario of two-tier tariff and a power purchase agreement price of 16.3c is an element of/kWh(e), the new SG layout yields an extra economic benefit of 623 k is an element of per year due to an increase of energy produced of 5.71 GWh(e),/year.

Beam-down concentrating solar power for thermochemical and energy absorption applications stands as an attractive approach that can enhance the renewable energies deployment. This work explores the integration of beam-down optics with fluidized bed technology proposing a model to calculate both gas and bed temperatures. The beam-down system concentrates the energy from the solar field into a fluidized bed receiver. A novel phenomenological model is proposed to adapt the well-known two-phase theory to the heat transfer process of a bed operating in the bubbling regime while it is directly irradiated from the top. In this way, this simple model can be used as a design tool for beam-down fluidized bed receivers. The top bed surface is considered as an opaque diffuse layer formed by gray particles. A single layer model is applied to estimate the effective emissivity between the heterogeneous bed surface and the ambient conditions in the freeboard. The vertical temperature profile is obtained considering particle phase heat conduction, particle to gas heat convection, solid convection, bubble convection and radiation heat transfer mechanisms. The model is validated using silicon carbide and zirconia fluidized bed experiments reported in the literature. The model shows that the solid convection is the dominant heat transfer mechanism for a beam-down fluidized bed receiver. Further results explore the influence of the operating conditions on the fluidized bed receiver for a bed of silicon carbide particles, showing that energy concentration fluxes of 35 . 10(4) W/m(2) can reach bed temperatures of 1000 degrees C when operating at a gas velocities of 3.U-mf.

Solar power tower plants differ from conventional power plants in the steam generator design due to the higher heat duty. In this work, the influence of the steam generator heat exchangers (preheater, evaporator, superheater and reheater) on a solar power plant with molten salt receiver and thermal storage is studied for the first time. Energy, exergy and exergoeconomic analyses give a complete view of the cost flows within the system. The pinch point temperature difference in the evaporator is used as the main variable as it changes the steam generator design and the operating conditions of the plant, such as the inlet temperature of the receiver and the salt mass flow. All heat exchangers are designed and optimized at minimum cost for each pinch point to fulfill the thermomechanical limitations of TEMA standards and Pressure Vessel code. The field of heliostats, molten-salt receiver and the power-block (110 MWe) designs are kept constant throughout the paper. A low pinch point should be used to minimize the plant exergy destruction while the exergoeconomic approach obtains an optimum pinch point around 2-3 °C. Furthermore, the low exergoeconomic factor values show that the heat exchangers of the SG are crucial for the plant operation.

This paper presents a methodology to guide the design of heat exchangers for a steam generator in a solar power tower plant. The low terminal temperature difference, the high fluid temperatures and the high heat duty, compared to other typical shell and tube heat exchanger applications, made the design of the steam generator for molten-salt solar power towers a challenge from the thermomechanical point of view. Both the heat transfer and the thermal stress problems are considered to size the preheater, evaporator, superheater and reheater according to the TEMA standards and ASME Pressure Vessel code. An integral cost analysis on the steam generator design effects on the power plant performance reveals an extremely low value for the optimum evaporator pinch point temperature difference. Furthermore, an optimization using genetic algorithms is performed for each heat exchanger, which leads to economical and feasible designs. A 110 MWe solar power tower plant is studied. Two configurations of the steam generator are proposed: with one or two trains of heat exchangers. The results show that the optimum pinch point temperature differences are very close to 2.6 degrees C and 3 degrees C for the steam generator with one and two trains, respectively. The proposed design of the steam generator consists of a U-shell type for superheater and reheater, a TEMA E shell forced circulation evaporator and a TEMA-F shell preheater. Also, the approach point temperature difference analysis is performed to avoid subcooled flow boiling in the pre-heater. An economic study to compare forced and natural circulation evaporator designs is carried out.

A novel approach to estimate the size of stagnant regions in large-scale fluidized beds by means of experimental data obtained from images recorded on the bed surface was presented. For this purpose, the internal structure of an induced maldistributed pseudo-2D fluidized bed was first studied. Half of the total distributor area was covered to generate an induced stagnant region. The size and shape of this area was studied for several relative gas velocities and bed aspect ratios. The defluidized area was found to be almost independent of the bed aspect ratio, however, it was found to decrease for higher relative gas velocities. A solids recirculation zone was also found above the defluidized zone. The size of this zone increases with relative gas velocity, suggesting that it is strongly related to bubble motion. A correlation was developed to relate the visible bubble flow to the size of the defluidized zone. The results obtained in the 2D bed were extrapolated to a 3D cylindrical fluidized bed with a half-covered distributor plate to estimate the volume of the defluidized zone. The visible bubble flow in the 3D facility was estimated. Using the proposed correlation for the defluidized volume in the 2D bed was used to estimate the defluidized volume in the 3D bed. Finally, the calculated values of the defluidized volume were compared with the experimental values in the 3D facility, obtaining a maximum relative error of 20% in the estimations.

A statistical method based on approximation of the cumulative energy distribution by Student's t-distribution is proposed for the unbiased frequency domain division. The proposed method fixes the number of samples needed to estimate the power spectrum and its corresponding cumulative energy distribution using the Kolmogorov&-Smirnov test. The reliability of the method to divide the frequency domain was shown for different fluidization velocities by changing the bed aspect ratio and using different pressure probes. Water-induced defluidization tests were conducted to illustrate the use of wide band energy as a monitoring tool. The Student's t-distribution results are compared with an analysis performed using the traditional visual inspection method. The energy of the power spectrum contained within the frequency regions obtained by the visual method is not able to detect changes in the bed aspect ratio or the start of the rotating distributor. No meaningful differences could be observed in the frequency regions using different quality pressure sensors because the approach using Student's t-distribution focuses on the sharp energy increase produced by the primary frequencies of the power spectrum. The sensitivity exhibited by the proposed frequency division approach for the range of fluidization conditions tested improves the use of the energy contained in these regions as a diagnostic tool in fluidized bed processes. The author would like to express appreciation for the financial support from Projects DPI2009-10518 (MICINN) and CARDENER-CM (S2009ENE-1660). Publicado

The fluidization conditions of a rotating distributor applied to a 3-D bubbling fluidized bed was studied to assess its potential use as a counteracting measure of defluidization phenomena. The performance of the fluidized bed operating under nominal conditions was characterized for the rotating and the static distributor configuration. Different methods of analysis in the time and frequency domain were applied to establish the performance of the fluidized bed. The frequency domain analysis suggests some kind of local structuring of fluidized bed dynamics imposed by the distributor motion. The punctual injection of water over the surface of the bed lead to a high cohesive wet region that tend to settle down on top of the distributor giving rise to defluidization. The water-induced defluidization tests reflect an improvement of the fluidization quality with the distributor rotation. The author would like to thank the financial support from Projects DPI2009-10518 (MICINN) and CARDENER-CM (S2009ENE- 1660) Publicado

This paper is addressed to introduce a methodology based on low frequency accelerometry that can be used for gas solid fluidized bed monitoring,and for dynamic diagnosis purposes. The proposed methodology consists on extracting the low frequency information encoded within an accelerometry signal, by means of the Hilbert transform method. The time and the frequency domain analysis show how thislow frequency information is directly related to the conventional pressure fluctuation measurements, providing useful information on bulk and bubble dynamics. The cross correlation and the coherence function analysis between the pressure and the envelope process of the measured accelerometer signals ‘‘E’’, exhibit values approaching unity for frequencies ranging between 2 and 4 Hz. This reveals that pressure signals and accelerometry envelope are related processes. Theresults from the Coherent Output Power, COP, and the Incoherent Output Power, IOP, analysis confirms that both pressure and envelope time series exhibit the same global and local features open the possibility of using low frequency accelerometers instead of conventional pressure transducers for monitoring and for dynamic diagnosis purposes Publicado

This contribution is aimed to give a fast view of State Space Analysis by presenting some codes written as m-files that can serve to understand the know-how methodology behind this advanced analytical tool, and yet little known. Mutual Information Function, reconstruction of the attractor system and correlation dimension allow to identify the time series under study as periodic, random or chaotic. Moreover, they can be used to characterize the underlying dynamics when the time series is collected from a physical system. Some version of the m-files can be free downloaded from: http://www2.uah.es/dep_qaiq/caos/text_en.htm