Estudio experimental y numérico de sistemas híbridos de climatización activados a baja temperatura basados en ruedas desecantes y enfriadores evaporativos indirectos

El tratamiento de aire en edificios con altas cargas latentes habitualmente requiere un alto coste energético para satisfacer las necesidades de confort térmico de los usuarios. Piscinas climatizadas o spas son algunos ejemplos de este tipo de edificios, los cuales tienen altas ganancias latentes internas, debido a la gran cantidad de agua evaporada en las áreas húmedas. Excesiva humedad del aire podría causar disconfort para los ocupantes y problemas relacionados a la calidad del aire interior de los edificios, debido a hongos y podredumbre. Los sistemas de climatización convencionales, basados en unidades de expansión directa, son ampliamente usados en la deshumectación del aire. Sin embargo, los sistemas de climatización convencionales presentan algunas limitaciones en el tratamiento combinado de las cargas sensibles y latentes. Estos sistemas usualmente solo controlan las cargas sensibles, temperatura del aire, o las cargas latentes, humedad del aire, pero no ambas cargas. Además, los caudales de aire de impulsión requeridos por los sistemas de climatización convencionales a veces son muy altos, con el fin de obtener altas capacidades desecantes. Excesivo caudal de aire también puede causar disconfort a los ocupantes. Los sistemas de climatización híbridos compuestos de ruedas desecantes y enfriadores evaporadores indirectos podrían ser una alternativa a los sistemas convencionales, debido a su alta capacidad desecante y de enfriamiento, respectivamente. El objetivo principal de esta tesis fue analizar experimentalmente y numéricamente el rendimiento de un novedoso sistema de climatización híbrido activado a baja temperatura y basado en ruedas desecantes y enfriadores evaporativos indirectos, para su uso en pequeños edificios con altas cargas latentes. En primer lugar, se analizaron experimentalmente una rueda desecante y un enfriador evaporativo indirecto, donde se obtuvieron las variables influyentes sobre los dispositivos fueron obtenidas y diversos modelos simplificados empíricos fueron ajustados. A continuación, se desarrolló una estrategia de control del calor sensible y latente, con el objetivo de controlar independientemente la temperatura y humedad del aire de impulsión. Un desacoplamiento de la temperatura y humedad del aire de impulsión pudo ser obtenido cuando el caudal del aire de proceso y la temperatura del aire de regeneración en la rueda desecante, y el caudal de agua en el enfriador evaporativo indirecto fueron variados. Finalmente, se analizó un novedoso sistema de climatización híbrido activado a baja temperatura y basado en ruedas desecantes y enfriadores evaporativos indirectos, y se comparó con un sistema de climatización convencional. Ambos sistemas de climatización fueron diseñados para servir aire en un pequeño edificio con altas cargas latentes, tales como spas. Se realizaron diversas simulaciones energéticas anuales para diferentes condiciones climáticas, las cuales estuvieron basadas en los modelos simplificados experimentales de la rueda desecante y el enfriador evaporativo indirecto., analizando la eficiencia energética de cada sistema de climatización. El sistema de climatización híbrido alcanzó mayor eficiencia energética que el sistema de climatización convencional cuando ambos sistemas servían aire a un pequeño edificio con altas cargas latentes, independientemente de las condiciones climáticas. Además, el sistema de climatización híbrido controló adecuadamente las cargas sensibles y latentes del edificio, usando reducidos caudales de aire de impulsión. Por lo tanto, esos resultados sugieren que el sistema de climatización híbrido podría ser una seria alternativa a los sistemas de climatización convencional para tratar aire en pequeños edificios con altas cargas latentes y donde reducidos caudales de aire de impulsión son requeridos.Air handling in buildings with high latent loads usually requires a high-energy cost to satisfy the user’s thermal comfort needs. Indoor swimming pools or spas are some examples of this type of buildings, which have high internal latent gains, due to the great amount of evaporated water from the wet areas. Excessive air humidity can cause discomfort for the occupants and problems related to the indoor air quality of the building due to fungus and rot. Conventional HVAC systems based on direct expansion units are widely used in dehumidifying air. However, conventional HVAC systems present some limitations in the combined treatment of sensible and latent loads. These systems usually only control sensible loads, air temperature, or latent loads, air humidity, but not both loads. Moreover, the supply air flow rates required by conventional HVAC systems are sometimes very high, in order to obtain high desiccant capacities. Excessive air flow rate can also cause discomfort to the occupants. Hybrid HVAC systems composed of desiccant wheels and indirect evaporative coolers could be an alternative to conventional HVAC systems, due to their high desiccant and cooling capacity, respectively. The main objective of this thesis was to analyse experimentally and numerically the performance of a novel hybrid HVAC system activated at low temperature based on desiccant wheels and indirect evaporative coolers for use in small buildings with high latent load. Firstly, a desiccant wheel and an indirect evaporative cooler were analysed experimentally, where the influence input variables on the devices were obtained and several empirical simplified models were fitted. Then, a sensible and latent heat control strategy was developed in order to independently control the supply air temperature and humidity ratio. A decoupling of the supply air temperature and humidity ratio can be obtained when the process air flow rate and air regeneration temperature in the desiccant wheel, and the water flow rate in the indirect evaporative cooler were varied. Finally, a novel hybrid HVAC system activated at low temperature based on desiccant wheels and indirect evaporative coolers was analysed and compared to a conventional HVAC system. Both HVAC systems were designed to serve air in a small building with high latent loads, such as spas. Several annual energy simulations for different climatic conditions were performed, which were based on the experimentally simplified models of the desiccant wheel and the indirect evaporative cooler, analysing energy efficiency of each HVAC system. The hybrid HVAC system achieved higher energy efficiency than the conventional HVAC system when both HVAC systems served air to a small building with high latent loads, regardless of the climatic conditions. Furthermore, the hybrid HVAC system suitably controlled the sensible and latent loads of the building, using reduced supply air flow rates. Therefore, these results suggest that the proposed hybrid HVAC system could be a serious alternative to conventional HVAC systems to handle air in small buildings with high latent loads and where reduced supply air flow rates are required

Molybdenum-catalyzed enantioselective sulfoxidation controlled by a nonclassical hydrogen bond between coordinated chiral imidazolium-based dicarboxylate and peroxido ligands

Chiral alkyl aryl sulfoxides were obtained by molybdenum-catalyzed oxidation of alkyl aryl sulfides with hydrogen peroxide as oxidant in mild conditions with high yields and moderate enantioselectivities. The asymmetry is generated by the use of imidazolium-based dicarboxylic compounds, HLR. The in-situ-generated catalyst, a mixture of aqueous [Mo(O)(O2)2(H2O)n] with HLR as chirality inductors, in the presence of [PPh4]Br, was identified as the anionic binuclear complex [PPh4]{[Mo(O)(O2)2(H2O)]2( -LR)}, according to spectroscopic data and Density Functional Theory (DFT) calculations. A nonclassical hydrogen bond between one C–H bond of the alkyl R group of coordinated (LR)- and one oxygen atom of the peroxido ligand was identified as the interaction responsible for the asymmetry in the process. Additionally, the step that governs the enantioselectivity was theoretically analyzed by locating the transition states of the oxido-transfer to PhMeS of model complexes [Mo(O)(O2)2(H2O)( 1-O-LR)]- (R = H, iPr). The DDG6= is ca. 0 kcal mol-1 for R = H, racemic sulfoxide, meanwhile for chiral species the DDG6= of ca. 2 kcal mol-1 favors the formation of (R)-sulfoxide.Junta de Andalucía (Proyecto de Excelencia FQM-7079)Universidad de Sevilla (VI Plan Propio

Revisiting the Redox Transitions of Polyaniline. Semiquantitative Interpretation of Electrochemically Induced IR Bands

The redox transitions of PANI in acidic medium have been monitored by a combination of cyclic voltammetry, in situ conductance and in situ FTIR spectroscopy. The results of the semiquantitative analysis strongly suggest that the classical tetrameric model of PANI does not satisfactorily describe the actual structures of the polymer at different redox states. An octameric model is revisited, with the inclusion of essential resonant structures, to provide an appropriate prediction of the relative IR intensity changes of the aromatic C-C stretching (at around 1520 cm-1) and the quinoid C=C stretching (at around 1590 cm-1) vibrations observed by FTIR, which are difficult to interpret by considering only 4 aniline rings. Particularly, it is found that the emeraldine state is better described as a resonance hybrid of the classical bipolaronic and semiquinoid (polaron lattice) structures, while most of the charge transferred at the onset of the second voltammetric peak comes from the additional oxidation of this hybrid, which becomes unstable in the electrochemical environment producing mineralization to CO2 and release of soluble quinones.This work was financed by the Spanish Ministerio de Ciencia e Innovación (project PID2019-105923RB-I00) and by Generalitat Valenciana (Conselleria de Educación, Investigación, Cultura y Deporte through project PROMETEO/2018/087)

Electrodos de Diamante Dopado con Boro para el tratamiento electroquímico de aguas

Boron-doped diamond electrodes have emerged as anodic material due to their high physical, chemical and electrochemical stability. These characteristics make it particularly interesting for electrochemical wastewater treatments and especially due to its high overpotential for the Oxygen Evolution Reaction. Diamond electrodes present the maximum efficiency in pollutant removal in water, just limited by diffusion-controlled electrochemical kinetics. Results are presented for the elimination of benzoic acid and for the electrochemical treatment of synthetic tannery wastewater. The results indicate that diamond electrodes exhibit the best performance for the removal of total phenols, COD, TOC, and colour.Los electrodos de diamante dopados con boro han surgido como un nuevo material anódico debido a su propiedades como estabilidad física, química y electroquímica. Estas características hacen a estos electrodos especialmente interesantes para el tratamiento electroquímico de aguas residuales, debido sobre todo a su elevado sobrepotencial para la reacción de formación de oxígeno. Los electrodos de diamante presentan una eficiencia máxima para la eliminación de contaminantes en el agua, sólo limitada por la cinética del proceso electroquímico controlado por difusión. Se muestran algunos ejemplos como en la eliminación de ácido benzoico y en el tratamiento electroquímico de aguas sintéticas del curtido de pieles. Los resultados indican que los electrodos de diamante muestran el mejor rendimiento para la eliminación de fenoles, DQO, COT, y del color

Absorption cross-sections of hole polarons in glassy and beta-phase polyfluorene

F. Montilla acknowledges financial support provided by Ministerio de Economía y Competitividad (Ramón y Cajal RYC1463/06 and José Castillejo JC2009-00 227 Programs). The authors also acknowledge the Engineering and Physical Sciences Research Council for financial support.Absorption induced by electrochemically injected holes is studied in poly-9,9-dioctylfluorene (PFO) films. Injected charges form positive polarons which are delocalised over four fluorene units in the glassy phase and about seven fluorene units in its beta-phase. Polaron absorption cross-sections at the 640 nm peak are similar to the published values of chemically reduced oligofluorenes in solution. The absorption cross-section of polaron in the beta-phase at 470 nm is about eight times smaller than the stimulated emission cross-section derived from published data. This indicates that beta-phase-rich PFO is an attractive candidate for a lightemitting layer in double-heterostructure organic laser diodes.Publisher PDFPeer reviewe

Revisiting the redox transitions of Polyaniline. Semiquantitative interpretation of electrochemically induced IR bands

[EN] The redox transitions of PANI in acidic medium have been monitored by a combination of cyclic voltammetry, in situ conductance and in situ FTIR spectroscopy. The results of the semiquantitative analysis strongly suggest that the classical tetrameric model of PANI does not satisfactorily describe the actual structures of the polymer at different redox states. An octameric model is revisited, with the inclusion of essential resonant structures, to provide an appropriate prediction of the relative IR intensity changes of the aromatic Csingle bondC stretching (at around 1520 cm¿1) and the quinoid Cdouble bondC stretching (at around 1590 cm¿1) vibrations observed by FTIR, which are difficult to interpret by considering only 4 aniline rings. Particularly, it is found that the emeraldine state is better described as a resonance hybrid of the classical bipolaronic and semiquinoid (polaron lattice) structures, while most of the charge transferred at the onset of the second voltammetric peak comes from the additional oxidation of this hybrid, which becomes unstable in the electrochemical environment producing mineralization to CO2 and release of soluble quinones.This work was financed by the Spanish Ministerio de Ciencia e Innovacion (project PID2019-105923RB-I00) and by Generalitat Valenciana (Conselleria de Educacion, Investigacion, Cultura y Deporte through project PROMETEO/2018/087). The authors of this work are deeply grateful to Prof. Jose Luis Vazquez Pico (Pepe, nowadays retired) for his mentorship, which was the seed to develop this work. We appreciate the wise advice he gave us during our careers which served us to deepen the science contained in this article, as well as for the friendship with which he honored us over the years.Huerta, F.; Quijada, C.; Montilla, F.; Morallón, E. (2021). Revisiting the redox transitions of Polyaniline. Semiquantitative interpretation of electrochemically induced IR bands. Journal of Electroanalytical Chemistry. 897:1-11. https://doi.org/10.1016/j.jelechem.2021.115593S11189

Justificación logica y seguridad epistémica en internet

This work seeks to answer the question of whether the Internet is epistemically secure. The problem is approached from a double path (i) analytical (a priori, logical-philosophical) and (ii) empirical. For the first, the treatment is based on the logic of justification; while the second, in a survey in which respondents answer on the use and assessment of the information offered by the internet. The argument presented is as follows: If epistemic security requires the exercise or implementation of epistemic virtues and those practices by the user are weak, then the Internet is not epistemically secure. Based on the established results, it is concluded that the internet is not epistemic safe and some risks that this entails are discussed

¿ES COHERENTE LA TESIS DE VAGUEDAD ONTOLÓGICA?

Evans’ conception of ontological vagueness is presented critically, contrasting his ideas with Anna Maidens’ perspective. While Evans rejects ontological vagueness, Maidens argues that quantum particles are good candidates to be considered as vague objects. It is argued that ontological vagueness thesis is not adequate and that quantum particles are not good candidates as Maidens suggests. Instead, vagueness is best understood as a semantic phenomenon. From this point of view, I suggest that the Russellian approach against ontological vagueness thesis offers better contention than Evans’ one.La concepción de la vaguedad de Evans es presentada críticamente. Mientras Evans niega la vaguedad ontológica, Maidens sostiene que las partículas cuánticas son buenas candidatas para ser consideradas como objetos vagos. Se argumenta que la tesis de vaguedad ontológica es inadecuada y que las partículas cuánticas no son buenas candidatas como sugiere Maidens. En su lugar, la vaguedad se entiende mejor como un fenómeno semántico. Desde esta perspectiva, sugiero que la aproximación russelliana contra la tesis de la vaguedad ontológica ofrece mejores argumentos que la de Evans

La participación de la tropa en la sublevación del Palmar

El 8 de julio de 1819 intentó pronunciarse parte del Ejercito expedicionario de Ultramar que mandaba el conde de La Bisbal. Para que la empresa tuviese éxito se aprovechó el descontento de la tropa con el embarque y se realizó una labor previa de atracción y de adoctrinamiento de estas clases para que apoyasen el levantamiento junto a sus oficiales liberales. Parte de la dinámica de este proceso de atracción es la que se expone en este trabajo.On July 8th, 1819 part of the expeditionary Army of Overseas that was led by the count of La Bisbal, tried to rebel. In order that the company had success it was taken advantage of the dissatisfactlon of the troop with the shipment and there was realized a previous labour of attractlon and of indoctrination of these classes in order to leaning the raising together with theirs liberal officlals. Part of the dynamics of this process of attraction is the one that is exposed In this work