Simulation of heat and mass transfer phenomena in the critical elements of H2O-LiBr absorption cooling machines. Experimental validation and application to design

Degut a la tendència a l'increment del preu de la energia, i el seu ús cada cop més estès per aire condicionat en els paisos desenvolupats, els sistemes de refrigeració basats en energia solar tenen cada cop més atractiu. El objectiu final d'aquesta tesi és el desenvolupament d'eines de simulació numèrica pel disseny de màquines de refrigeració per absorció que tinguin la possibilitat de funcionar amb energia solar. Malgrat existeixen en el mercat màquines d'absorció d'aquestes característiques des de fa anys, hi ha una deficiència en el desenvolupament de sistemes de petita capacitat. Els sistemes de petita capacitat impliquen problemes addicionals en el seu disseny (sistemes refrigerats per aire, compacitat ...) que només es poden abordar fent ús d'eines de disseny adequades, tant pel sistema com pels seus components. Tanmateix, hi ha també certa deficiència en la literatura especialitzada en el desenvolupament de models matemàtics adequats per la descripció dels processos de transferència de calor i de massa en les màquines de refrigeració per absorció: àrea mullada en les superfícies d'intercanvi de calor i de massa, paper dels additius, etc. Per aquestes raons aquest treball ha estat enfocat en aquests objectius:- Estudi de processos bàsics de transferència de calor i de massa juntament amb els fenomens fluid-dinàmics implicats en absorbidors de màquines d'absorció. Aquest estudi ha estat fet mitjançant simulacions detallades resolent les equacions de Navier-Stokes sota ertes hipòtesis.- Desenvolupament d'eines de simulació numèrica pel disseny i predicció de sistemes de refrigeració per absorció, aprofitant la informació donada per models més detallats.- Desenvolupament d'eines de simulació numèrica pel disseny dels elements crítics d'intercanvi de calor i de massa de sistemes de refrigeració per absorció (absorbidor, generador, evaporador, condensador) mantenint el càlcul en un raonable temps de CPU. Aquest model recolza el mencionat en el punt anterior.- Desenvolupament de un prototipus de màquina d'absorció, refrigerada per aire, fent servir H2O-LiBr com a fluid de treball, amb les eines numèriques desenvolupades. - Contrastació experimental dels models desenvolupats.- Estudi del funcionament de la màquina d'absorció anteriorment mencionada. - Avaluació dels resultats per millorar els criteris de disseny i optimització del mateix de cara a prototipus de segona generació.Després del desenvolupament d'aquestes eines de simulació numèrica que s'han fet servir per problemes específics sortits en el procés d'estudi d'una màquina en concret, un marc de treball ha estat creat per l'estudi d'altres sistemes de refrigeració per absorció.Due to the increasing trend of the price of the energy, mainly obtained from fossil combustibles, and its also increasing use for air-conditioning in developed countries, solar cooling has been becoming more attractive from the point of view of economics and environment conservation. The final aim of this thesis is the development of numerical simulation tools for the design of absorption machines with the possibility of being driven by solar energy. Although there are available in the market absorption chillers of such characteristics for years, there is a lack in development of small capacity systems. Small capacity systems imply additional problems of design (air-cooled systems, compactness ...) that only can be afford with adequate design tools for system and components. Moreover, there is also a lack in the specialised literature in the development of adequate mathematical models for the description of the heat and mass transfer processes in absorption machines: wetted area of the heat and mass transfer surfaces, role of additives, complex geometries etc.For these reasons this work has been focused on the following detailed objectives: - Study of basic heat and mass transfer processes together with the fluid-dynamic phenomena implied in absorbers of absorption chillers. This study has beencarried out by means of detailed simulations solving the Navier-Stokes equations under certain hypotheses. - Development of numerical simulation tools for design and prediction of absorption systems, taking advantage of information given by more detailed models. - Development of numerical simulation tools for design of the heat and mass exchange components of absorption systems keeping the calculation in a reasonable CPU time. This model provides of the necessary information for the model mentioned in the previous point.- Development of a prototype of an air cooled absorption machine based on the numerical results obtained from the models.- Validation of the models developed by means of comparison of numerical results and experimental data obtained from the prototypes developed.- Study of the performance of the above mentioned absorption system. - Evaluation of the results in order to improve the design criteria for a second generation of prototypes.After the development of these numerical simulation tools and their applicationin specific problems, a framework has been created for the study of other type of absorption systems.Postprint (published version

Bothrops nasuta

Number of Pages: 2Integrative BiologyGeological Science

Consumer Motivations to Participate in Marketing-Events: The Role of Predispositional Involvement

Confronted with the decreasing effectiveness of classic marketing communications, event-marketing has become an increasingly popular alternative for marketers in dealing with a changing marketing environment. Event-marketing is defined as the creation of 3-dimensional, interactive brand-related hyperrealities for consumers by staging marketing-events, which would result in an emotional attachment to the brand. However, as a pull strategy within marketing communications, successful event-marketing strategies require a thorough understanding of why consumers are motivated to voluntarily participate in those marketing-events. To narrow this information gap, this research, based on a thorough literature review, has developed a conceptual model suggesting that consumers’ motivations to participate in marketing-events are determined by their predispositional involvement either in the event-object, the event-content, event-marketing or the expected social interaction at the event. Thus, the main contribution is to the involvement and experiential consumption literature

Book review: The Most Sublime Hysteric: Hegel with Lacan by Slavoj Žižek

Available in English for the first time, this publication from Slavoj Žižek represents a re-worked version of one of his earliest works. Hard to place amongst his recent works, perhaps the purpose of publishing this early work is to make us realise that the 1980s Žižek was already then the one we have come to recognise, just as the content of the book retroactively makes Hegel a Lacanian avant la lettre, writes Jodie Matthews

Rhineura

Number of Pages: 2Integrative BiologyGeological Science

Hybrid system of expert system and artificial neural networks for objective evaluation of product sensuous quality

Basic problems and the bottleneck of current approaches for objective assessment of product sensuous quality (PSQ) are discussed. As a solution, a new approach, an expert system (ES) based on artificial neural networks (ANNs) is proposed, in which the ES and ANNs co-operate in a superiority compensation way. T he knowledge base of the system can be effectively built and the evaluation of PSQ can be conducted on-line. As a case study, the new approach has been applied in leather handle test and it proves that the approach is capable of handling non-linear relationships among multiple measured PSQ parameters

Classifying document types to enhance search and recommendations in digital libraries

In this paper, we address the problem of classifying documents available from the global network of (open access) repositories according to their type. We show that the metadata provided by repositories enabling us to distinguish research papers, thesis and slides are missing in over 60% of cases. While these metadata describing document types are useful in a variety of scenarios ranging from research analytics to improving search and recommender (SR) systems, this problem has not yet been sufficiently addressed in the context of the repositories infrastructure. We have developed a new approach for classifying document types using supervised machine learning based exclusively on text specific features. We achieve 0.96 F1-score using the random forest and Adaboost classifiers, which are the best performing models on our data. By analysing the SR system logs of the CORE [1] digital library aggregator, we show that users are an order of magnitude more likely to click on research papers and thesis than on slides. This suggests that using document types as a feature for ranking/filtering SR results in digital libraries has the potential to improve user experience.Comment: 12 pages, 21st International Conference on Theory and Practise of Digital Libraries (TPDL), 2017, Thessaloniki, Greec

Architecture and the automobile from the 1920s to the 1950s : relationship and evolution of their technique and form, from mechanicist design to organicist design

Els avenços de la industrialització a la primera meitat del segle XX van portar un revolucionari i ràpid desenvolupament de la producció, que va influir en innombrables camps, un d'ells l'arquitectura, disciplina que ha evolucionat utilitzant la indústria com a font de coneixement. Les indústries del transport, com l'aeronàutica, la naval i l'automobilística, van influir notablement a l'arquitectura de la primera meitat del segle XX. Fins als anys 30, els seus dissenys solien basar-se en la juxtaposició i l'assemblatge d'elements independents, mentre que a partir d'aquella dècada, els seus dissenys esdevingueren més orgànics i amb elements més ben entrellaçats. En són un bon exemple les dues fotografies de la portada d'aquesta obra: La Casa Doble de Le Corbusier a Weissenhofsiedlung juntament amb el Mercedes-Benz 8/38 hp Roadster i el Pavelló Upper Lawn d'Alison i Peter Smithson juntament amb el Citroën DS 19. En aquest sentit, aquesta obra se centra en la relació tècnica i formal entre l'arquitectura i l'automòbil, de la qual veurem i analitzarem nombrosos exemples del període comprès entre les dues fotografies de la portada, és a dir, entre els anys vint i els cinquanta.Los avances de la industrialización en la primera mitad del siglo XX trajeron consigo un revolucionario y rápido desarrollo de la producción, que influyó en innumerables campos, uno de ellos la arquitectura, disciplina que ha evolucionado utilizando la industria como fuente de conocimiento. Las industrias del transporte, como la aeronáutica, la naval y la automovilística, influyeron notablemente en la arquitectura de la primera mitad del siglo XX. Hasta los años 30, sus diseños solían basarse en la yuxtaposición y el ensamblaje de elementos independientes, mientras que a partir de esa década, sus diseños se volvieron más orgánicos y con elementos mejor entrelazados. Buen ejemplo de ello son las dos fotografías de la portada de esta obra: La Casa Doble de Le Corbusier en Weissenhofsiedlung junto con el Mercedes-Benz 8/38 hp Roadster y el Pabellón Upper Lawn de Alison y Peter Smithson junto con el Citroën DS 19. En este sentido, esta obra se centra en la relación técnica y formal entre la arquitectura y el automóvil, de la que veremos y analizaremos numerosos ejemplos del periodo comprendido entre las dos fotografías de la portada, es decir, entre los años veinte y los cincuenta.The advances in industrialisation in the first half of the 20th century brought about a revolutionary and rapid development of production, which influenced countless fields, one of them being architecture, a discipline that has evolved using industry as a source of knowledge. The transport industries, such as aircraft, ship and automobile, had a significant influence on architecture during the first half of the 20th century. Until the 1930s, their designs tended to be based on the juxtaposition and assembly of independent elements, while from the 1930s onwards, their designs became more organic and with better interlocking elements. Good examples of this are the two photographs on the cover of this work: Le Corbusier's Double House in Weissenhofsiedlung together with the Mercedes-Benz 8/38 hp Roadster and Alison and Peter Smithson's Upper Lawn Pavilion together with the Citroën DS 19. In this sense, this work focuses on the technical and formal relationship between architecture and the automobile, of which we will see and analyse numerous examples from the period between the two photographs on the cover, in other words, between the 1920s and the 1950s

Reflections on eportfolio professional learning: harnessing an unconference approach

This practitioner-led article documents the journey of a cross-institutional multidisciplinary team to support the development of practitioners’ ePortfolio professional competencies through an “Unconference.” We describe the approach used to support an ePortfolio unconference hosted in January 2018 at Dublin City University. According to Budd et al. (2015), the most meaningful professional learning at conferences tends to occur at the cofee breaks when delegates are free to engage in open dialogue. An unconference is a dynamic participant-driven conference which features discussion and collaboration at its core to support professional learning. This approach was chosen to capture, develop and document current ePortfolio practice in Ireland and the United Kingdom. This article outlines key facets of professional learning generated as a result of the unconference including the promotion of ePortfolio competencies and the generation of collaborative research outputs. At the unconference, attendees participated in experiential learning opportunities which enhanced and extended their personal and professional ePortfolio competencies as well as developed practice-focused research outputs collaboratively in real time using a range of technological tools. Participant feedback highlights the impact of the unconference on their professional ePortfolio learning and practice, and the critical refections of unconference organizers inform future ePortfolio professional development