Fluidization of Group B particles with a rotating distributor

A novel rotating distributor fluidized bed is presented. The distributor is a rotating perforated plate, with 1% open-area ratio. This work evaluates the performance of this new design, considering pressure drop, Δp, and quality of fluidization. Bed fluidization was easily achieved with the proposed device, improving the solid mixing and the quality of fluidization. In order to examine the effect of the rotational speed of the distributor plate on the hydrodynamic behavior of the bed, minimum fluidization velocity, Umf, and pressure fluctuations were analyzed. Experiments were conducted in the bubbling free regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart's classification. The pressure drop across the bed and the standard deviation of pressure fluctuations, σp, were used to find the minimum fluidization velocity, Umf. A decrease in Umf is observed when the rotational speed increases and a rise in the measured pressure drop was also found. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess gas velocities. Measurements with several initial static bed heights were taken, in order to analyze the influence of the initial bed mass inventory, over the effect of the distributor rotation on the bed hydrodynamics.Publicad

Adecuación de recursos tecnológicos para la docencia de las matemáticas durante la pandemia de Covid-19

Lastra Sedano, Alberto (codirector)El presente trabajo tiene como objetivo realizar un estudio acerca de cómo se adaptó la enseñanza de las matemáticas durante la pandemia de COVID-19, en concreto el uso que hicieron los docentes de esta materia de las Tecnologías de la Información y la Comunicación (TIC) en los niveles educativos de Educación Secundaria Obligatoria y Bachillerato. Con este fin, y tras analizar primero el marco teórico en el que se engloba esta cuestión y las medidas que se adoptaron, se ha diseñado y difundido un cuestionario que ha sido previamente validado por expertos en el campo de la investigación educativa y cuyos resultados son, por tanto, legítimos y fiables. Las respuestas obtenidas arrojan cierta perspectiva sobre las fortalezas del empleo de las TIC en esta materia en concreto y permiten afirmar que existe un cierto rechazo por parte de los encuestados a la educación exclusivamente online, al menos en estos niveles educativos, y una demanda de formación en este ámbitoThe objective of this document is to carry out a study on how the teaching of mathematics was adapted during the COVID-19 pandemic, specifically the use made by teachers of Information and Communication Technologies (ICT), in Secondary Education and Baccalaureate. To this end, and after first analyzing the theoretical framework in which this issue is encompassed and the measures that were adopted, a questionnaire has been designed and sent, with the previous validation of experts in the field of educational research, which makes these results legitimate and reliable. The answers obtained shed some perspective on the strengths of the use of ICT in this specific area and allow us to affirm that there is a certain rejection by the respondents for exclusively online education, at least at these educational levels, and a clear demand for training.Máster Universitario en Formación del Profesorado de ESO, Bachillerato, Formación Profesional y Enseñanza de Idiomas. Especialidad en Matemáticas (M088

Distributor effects near the bottom region of turbulent fluidized beds

The distributor plate effects on the hydrodynamic characteristics of turbulent fluidized beds are investigated by obtaining measurements of pressure and radial voidage profiles in a column diameter of 0.29 m with Group A particles using bubble bubble-cap or perforated plate distributors. Distributor pressure drop measurements between the two distributors are compared with the theoretical estimations while the influence of the mass inventory is studied. Comparison is established for the transition velocity from bubbling to turbulent regime, Uc, deduced from the pressure fluctuations in the bed using gauge pressure measurements. The effect of the distributor on the flow structure near the bottom region of the bed is studied using differential and gauge pressure transducers located at different axial positions along the bed. The radial voidage profile in the bed is also measured using optical fiber probes, which provide local measurements of the voidage at different heights above the distributor. The distributor plate has a significant effect on the bed hydrodynamics. Owing to the jetting caused by the perforated plate distributor, earlier onset of the transition to the turbulent fluidization flow regime was observed. Moreover, increased carry over for the perforated plate compared with the bubble caps has been confirmed. The results have highlighted the influence of the distributor plate on the fluidized bed hydrodynamics which has consequences in terms of comparing experimental and simulation results between different distributor platesPublicad

Plastic fiber-optic probes for characterizing fluidized beds in bubbling regime

Bubble measurements on a fluidized bed in bubbling regime using optical fibre probes (OFP) are reported. Comparisons between commercial pressure transducers (PT) measurements and OFP have also been carried out. OFP are able to detect smaller bubbles than the PT and reflect more localized phenomena in the bed.Publicad

Cloning and sequence analysis of a vasa homolog in the European sea bass (Dicentrarchus labrax): Tissue distribution and mRNA expression levels during early development and sex differentiation

12 pages, 7 figuresVasa is a protein expressed mainly in germ cells and conserved across taxa. However, sex-related differences and environmental influences on vasa expression have not been documented. This study characterized the cDNA of a vasa homolog in the European sea bass, Dicentrarchuslabrax (sb-vasa), a gonochoristic fish with temperature influences on gonadogenesis. The 1911 bp open reading frame predicted a 637-amino acid protein with the eight conserved domains typical of Vasa proteins. Comparisons of the deduced amino acid sequence with those of other vertebrates and invertebrates revealed the highest homology (68–85%) with those of other teleosts. An updated tree with the full-length sequences for Vasa proteins in 66 species belonging to six different phyla was constructed, establishing the evolutionary relationships of Vasa amino acid sequences. European sea bass vasa was highly expressed in gonads with little or no expression in other tissues. Real time RT-PCR quantification of the temporal expression of sb-vasa from early development throughout sex differentiation showed that mRNA levels were high in unfertilized eggs, decreased during larval development and increased again during the period of germ cell proliferation. Rearing of fish at high temperature resulted in further increased sb-vasa levels, most likely reflecting temperature effects on both somatic and gonadal growth. Differences in expression were also found well before sex differentiation and persisted until the end of the first year, with higher levels present in females. These differences in expression demonstrate the implication of vasa during the initial stages of fish sex differentiation and gametogenesis and suggest that, through its helicase activity, it might be implicated in the translational regulation of mRNAs involved in the specification and differentiation of gonadal-specific cell typesThis work was supported by the EU grant PROBASS (Q5RS-2000-31365) to F.P and C.C.M. Research at the lab of F.P. is partially funded by project Consolider ‘‘Aquagenomics” CDS2007-0002. M. Blázquez was supported by a postdoctoral contract from the EU and a Ramón y Cajal contract from the Spanish Ministry of Science and TechnologyPeer reviewe

Performance of a LiBr water absorption chiller operating with plate heat exchangers

This paper studies the performance of a lithium bromide water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from 75°C to 105°C. In the condenser and the absorber, the inlet temperature of the cooling water goes from 20°C to 40°C. The coefficient of performance (COP) obtained ranges from 0.5 to 0.8 for cooling duties ranging from 2 kW to 12 kW. The chiller response to different hot fluid temperatures and circulated mass flow rates is also presented. The performance and the internal parameters of the chiller at part load are, therefore, calculated. A higher efficiency results when the solution pumped from the absorber to the desorber decreases. The heat transfer analysis of the PHEs is also presented. The overall heat transfer coefficient in the desorber, equal to 790 W/m²K at the design conditions, is also analysed at part load. The condenser performance can be represented by a similar relationship found in conventional air cooled condensersThis work was partially funded by CICYT Ministerio de Ciencia y Tecnología (CLIMABCAR project no. DPI 2003-01567)Publicad

Parametric study of operating and design variables on the performance of a membrane-based absorber

A plate-and-frame microchannel H2O&-LiBr absorber using a microporous membrane as contactor between the vapour and the solution is simulated. The heat and mass transfer equations, describing the absorption of the vapour phase into the solution, are solved for different membrane properties and for variable design and operating conditions. The parametric study evaluates the sensitivity of the ratio between the cooling capacity of the chiller and the absorber volume (rqV) to changes in the following parameters: width and height of the solution and cooling water channels; concentration, temperature and mass flow rate of the solution; temperature and mass flow rate of the cooling water; porosity, pore diameter, thickness and thermal conductivity of the membrane; thickness and thermal conductivity of the interface wall between the solution and the cooling water; and temperature, pressure and mass flow rate of the vapour. At the design stage of the membrane absorber, the parameters that can be optimised to maximise rqV are porosity, pore diameter, solution channels depth and membrane thickness. The thickness of the interface wall between the solution and the cooling water, as well as the solution channels width should be also taken into account. For a good performance during the operation of the absorber, special care should be taken to select the adequate vapour pressure and solution inlet temperature and concentration.The financial support of this study by the Ministerio de Economía y Competitividad of Spain through the research grant ENE2013- 43131-R is greatly appreciated

D10.1.1. Before analysis

WP Case study - Intelligent integrated decision support for legal professionalsThe objective of this document is to study the determining factors that exist in thelegal domain in Spain that can affect the achievement of a successful application in the Legal Case Study in the SEKT project. To do this,several surveys are presented, such as a user analysis, a domain analysis,a requirements analysis,a state of the art on legal applications anda state of the art on legal ontologie

Experimental characterisation of a novel adiabatic membrane-based micro-absorber using H2O-LiBr

In the interest of reducing the size of absorption chillers, a novel adiabatic membrane-based micro-absorber prototype is experimentally studied. Water-lithium bromide solution is used as the working fluid flowing through 50 rectangular microchannels of 0.15mm height, 3 mm width and 58 mm length. In the present study, a laminated microporous PTFE membrane of 0.45 µm pore diameter, separating the solution from the vapour, is tested. It incorporates a supporting layer of polypropylene. Different operating parameters were tested, including the inlet solution mass flow rate, temperature and concentration and the pressure potential for absorption. The measured concentration and temperature of the solution at the absorber outlet are used to evaluate the mass transfer characteristics of the micro-absorber. It is demonstrated that the process is controlled by the solution mass transfer resistance. Calculated results of the absorption rate and the absorption ratio show the advantages of the proposed design considering its compactness. The cooling power of a hypothetical chiller equipped with the tested micro-absorber of 73.7 cm3 effective volume, for the range of variables considered in this study, is 41 W. The modular configuration of the absorber allows to easily scale-up the cooling capacity

Modeling and performance analysis of an absorption chiller with a microchannel membrane-based absorber using LiBr-H2O, LiCl-H2O, and LiNO3-NH3

In order to develop compact absorption refrigeration cycles driven by low heat sources, the simulated performance of a microchannel absorber of 5-cm length and 9.5cm(3) in volume provided with a porous membrane is presented for 3 different solution-refrigerant pairs: LiBr-H2O, LiCl-H2O, and LiNO3-NH3. The high absorption rates calculated for the 3 solutions lead to large cooling effect to absorber volume ratios: 625kW/m(3) for the LiNO3-NH3, 552kW/m(3) for the LiBr-H2O, and 318kW/m(3) for the LiCl-H2O solutions given the studied geometry. The performance of a complete absorption system is also analyzed varying the solution concentration, condensation temperature, and desorption temperature. The LiNO3-NH3 and the LiBr-H2O solutions provide the largest cooling effects. The LiNO3-NH3 can work at a lower temperature of the heating source, in comparison with the one needed in a LiBr-H2O system. The lowest cooling effect and coefficient of performance are found for the LiCl-H2O solution, but this mixture allows the use of lower temperature heating sources (below 70 degrees C). These results can be used for the selection of the most suitable solution for a given cooling duty, depending on the available heat source and condensation temperature