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Though the number of studies on pool fires is relevant, the characteristics of boilover are not yet totally understood. Boilover is one of the most dangerous phenomena that can occur when the fuel is burning above a water layer; in this situation, due to heat transfer from the flame, water can reach ebullition and the consequent eruptive expulsion of vapour bubbles, drags fuel into the flame, increasing the thermal effect and the dimension of the fire. The phenomenon can present itself in two forms, depending on the fuel layer thickness, the hot zone boilover and the thin layer boilover, which boundaries are not yet well defined.Thus, this work can prove to be very important, since it aims to step forward in the knowledge of boilover, by defining in a clearer form its mechanisms and its effects, at a scale representative of a real fire scenario. The experiments realized concerned thin layer boilover, due to economical and security limitations; nevertheless, when it was possible, data have been extrapolated to situations of hot zone boilover.In order to carry on the study, an experimental facility was remodelled and enhanced; the facility has 5 circular pools of diameter ranging from 1.5 to 6 m. A series of thermocouples was used to determine the fuel and water temperatures. Other thermocouples were employed to analyze flame temperature distribution. Moreover, from the experiences much information was obtained, such as burning rate values, video-recordings (in the visible and IR field), intensity of radiation emitted to the exterior, atmospheric condition evolution, etc. Data proceeding from three experimental series, performed by CERTEC (Centre d'Estudis del Risc Tecnològic) since 1999, were analyzed.In great detail, the fundamental parameters of thin layer boilover (on-set time, pre-boilover burned mass ratio, boilover intensity, radiation intensity, etc.) as a function of the characteristics of the experiments (pool diameter, fuel type, fuel thickness, etc.) were studied.New correlations to estimate average and maximum flame length during the stationary period and the thin layer boilover, were obtained. Effects of the phenomenon on flame tilt and pulsation were also considered.Moreover, in order to calculate the increase to apply to safety distances in case of occurrence of the phenomenon, a semi-empirical model to estimate thermal effects during thin layer boilover was determined.The analysis of the distribution of the temperatures inside the water layer showed that, working with small fuel layers, there is no formation of a proper hot zone. It was only possible to determine a much reduced high temperature zone, which did not increase in thickness or temperature and has been named pseudo hot zone.Finally, a mathematical model to predict temperature distribution inside the liquid layer (fuel and water) during the process that leads to thin layer boilover was developed. The model, which showed the great importance of the convection inside the fuel for the heat transfer, was later modified and extended, in order to simulate the boilover phenomenon in a general form. The predictions of the model fit very well experimental data from this thesis and from previous publications. Furthermore, the results obtained allowed to observe that a combination of Prandtl and Fourier number can help in deciding the possibility and the type of boilover

La política Europea de transporte pretende alcanzar un sistema donde la sostenibilidad juegue un papel predominante. La reducción de lasemisiones contaminantes, de la accidentabilidad, la descongestión del tráfico en las carreteras constituyen un pilar fundamental paraalcanzar tal objetivo.La Unión Europea, a través de la Estrategia para un Desarrollo Sostenible del Libro Blanco de Transporte, ha manifestado en repetidasocasiones su preocupación por los impactos generados por el sector de los transportes; es por eso que existe la aplicación de medidaspara la solución de estos problemas para la integración de las cuestiones medioambientales en las políticas de transporte y los sectoresafines.En el conjunto del transporte, la carretera genera más del 80 por 100 de las emisiones de CO2, siendo con diferencia el modo máscontaminante, mientras que el transporte marítimo se mantiene como el modo menos contaminante. Esta situación, favorable al transportemarítimo se mantiene también para las emisiones de NOx a la atmósfera. Del total de este tipo de emisiones de la Unión Europea, el 51por 100 procede de los vehículos por carretera y un 12 por 100 de los medios de transporte.Hoy en día muchos países están trasladando el tráfico de mercancías de las autopistas congestionadas a otros modos de transporte.Muchas veces el tráfico marítimo, a parte del tráfico ferroviario de mercancías, son la alternativa más plausible para prevenir el incrementode transporte por carretera y las fuertes consecuencias económicas que comporta.A raíz de la firma del Tratado de Adhesión de España a la Unión Europea el año 1986, con el cual el transporte por carretera adquirió uncierto protagonismo, las tasas de crecimiento de tráfico, durante ese año, pasaron del 2,8% al 8,4%, manteniendo y totalizando unmovimiento de 70 millones de toneladas en ambos sentidos, lo que se traduce en una media de 3.500 camiones diarios en tránsito, através de los pasos de La Jonquera e Irún. Para el año 2020, aplicando una tasa de crecimiento similar a la experimentada estos últimosaños, el tráfico de mercancías podría verse incrementado a unos 250 millones de toneladas en total, y más de 30.000 camionesatravesando los Pirineos.Ante esta situación y las consecuencias derivadas de la congestión, es deseable lograr un trasvase de las clásicas cadenas de transporteunimodales a las cadenas multimodales, con la participación de medios terrestres y marítimos. Hoy en día, el reparto del tráfico demercancías se mantiene a un 50% entre ambas cadenas, aunque con una ligera ventaja del camión, sobretodo en recorridos cortos comoes el caso de trayectos entre España y Francia, mientras que a medida que las distancias se amplían lógicamente existe un trasvase haciael modo marítimo.De acuerdo con la revisión del Libro Blanco del Transporte de la Unión Europea, se espera que el Transporte Marítimo de Corta Distancia,en inglés Short Sea Shipping, crezca un 59% en toneladas métricas, desde el año 2000 al año 2020.La principal ventaja del Transporte Marítimo de Corta Distancia consiste en la posibilidad de combinar las ventajas inherentes de losdistintos modos de transporte implicados, reduciendo los costes e incrementando la capacidad de transportar gran volumen de carga enlargas distancias. Pero para poder convertir el transporte multimodal en una alternativa real al transporte unimodal por carretera a parte decuantificar y reducir los costes de fricción al cambiar de modo se deben identificar y estudiar un número de variables relacionadas con eltransporte de mercancías que nos permitirán conocer la viabilidad de una ruta.Para este trasvase de mercancías al modo marítimo se consideran principalmente los buques convencionales como la solución más viable,ya que pueden penetrar en el mercado por carretera reduciendo, en algunos casos, los costes internos y externos. Mientras esteargumento está basado en que el transporte por mar debería competir en precio (por ejemplo ofreciendo un precio más bajo que otrosmodos de transporte) también se debe de considerar la importancia de los buques de alta velocidad que ofrecen calidad al servicio. Losbuques de alta velocidad pueden ser unos posibles competidores del transporte terrestre en determinadas rutas; aunque estos buquespresentan problemas de operación cuando navegan con mal tiempo.El Transporte Marítimo de Corta Distancia debe responder a una serie de requisitos básicos para su identificación y puesta en servicio:buenas conexiones con un hinterland intermodal, un transporte mayoritariamente especializado en tráfico Ro-Ro, una velocidad mínima enlos buques, una alta frecuencia con un mínimo de salidas semanales y ofrecer la máxima fiabilidad aportando al mismo tiempo una mejorasignificativa de los costes de la cadena logística. A su vez, existen elementos críticos para su puesta en marcha que hay que tener encuenta: la consolidación de los flujos, la calidad del conjunto de la cadena de transporte, el compromiso de todos los elementos de lacadena de suministro y la compatibilidad con las otras vías de transporte hacia un modelo multimodal.Se evidencia la voluntad de la Comisión Europea para promocionar el Transporte Marítimo de Corta Distancia, como un modo mássostenible. Uno de los posibles caminos para mejorar su competitividad frente al transporte por carretera y el aéreo, puede pasar por eluso extensivo de buques rápidos o de alta velocidad.Es evidente que los buques de alta velocidad reducen el tiempo de viaje, pero para mantener la ganancia en tiempo en la mar, lasoperaciones en puerto también deben de reducirse para poder mantener la ventaja en el tiempo de viaje.Sin embargo más velocidad implica mayor consumo y más emisiones contaminantes. El aumento de velocidad es viable comercialmenteen unas rutas concretas y en unas condiciones determinadas: buen tiempo durante todo el año, una demanda suficientemente alta paracubrir la necesidad de una alta frecuencia y una situación geográfica favorable. / The European transport policy aims to achieve a sustainable communication system. A reduction in pollutant emissions, accident rate andtraffic congestion is central to reaching this goal.Through the Strategy for Sustainable Development of the EU White Paper on Transport Policy, the European Union has expressed concernabout transport-related impacts. For this reason, appropriate policies to balance transport growth and its environmental effects are being made.In general, road transport accounts for over 80% of CO2 emissions. It is, therefore, the most polluting mode of transportation whereas seatransport remains the least polluting. The same applies to NOx emissions. Road transport is responsible for 51% of these pollutant emissionsin the European Union, as opposed to 12% for the other modes.In many countries a shift from congested highways to other alternatives for freight transport has been observed. Apart from railway transport,the maritime option is often preferred to relieve road traffic congestion and its negative environmental effects.After Spain joined the European Union at 1986, the traffic volume increase had grown from 2.8% to 8.4% per year, accounting for a movementof 70 million tonnes in both directions. This means a daily average of 3,500 trucks travelling through La Jonquera and Irún passes. At this rate,by the year 2020, freight transport could increase to a total of 250 million tonnes, with over 30,000 trucks crossing the Pyrenees.In view of this and the consequences of traffic congestion, a change from traditional unimodal to multimodal transport chains involving the seaand road modes is desirable. Freight transport is currently shared by both chains, with a slight advantage of road over maritime transport,particularly in short distances like trips between France and Spain while the sea option logically becomes more common as distances increase.According to the review of the EU White Paper on Transport Policy, a 59% increase in tonnes carried by Short Sea Shipping is expectedbetween 2000 and 2020.The main benefit of Short Sea Shipping lies in the possibility of combining the inherent advantages provided by the involved modes, thusreducing costs and increasing freight transport capacity over long distances. However, for multimodal transport to become a real alternative tothe road-only mode, the feasibility of routes must be explored with several variables related to freight transport. Moreover, friction costs derivedfrom the mode shift must be quantified and reduced.Conventional ships are typically regarded as the most viable solution since they can penetrate the road market, sometimes leading to a declinein internal and especially external costs. While this opinion is based on the fact that sea transport should compete price-wise with other modes,it must be born in mind that high-speed vessels offer greater speeds, which may be perceived as quality of service by some shippers. In someroutes, high-speed vessels can become serious competitors to road transport although these ships pose operational problems in bad weather.Short Sea Shipping must meet a number of basic requirements to be efficiently implemented: good links with an intermodal hinterland, atransport mode specialised in Ro-Ro traffic, fast enough ships, sufficient number of weekly trips, maximum reliability and sharp decline in costsderived from the logistic chain. Also, certain critical factors must be taken into account, i.e. consolidation of flows, quality of the whole transportchain, commitment and compatibility of all elements of the supply chain with other transport modes with a view towards a multimodal model.The European Commission’s interest in promoting Short Sea Shipping as a more sustainable mode is made clear. One possible way ofincreasing competitiveness against road and air transport may be the extensive use of fast conventional or high-speed vessels.It is evident that high-speed vessels reduce travel time, but in order to maintain this advantage, port operations must also take less time.However, more speed implies greater consumption and a higher level of pollutant emissions. An increase in speed is commercially feasible incertain route and freight types and under specific conditions: good weather all year around, a demand large enough to justify high tripfrequency and a favourable geographical location.The use of fast conventional and high-speed ships is not always the best solution. It was necessary to examine each particular case. If in thefuture more policies towards sea transport are implemented and freight volume increases, high-speed services will have a market share largeenough to be commercially and economically feasible.The purpose of this thesis is to find alternatives to relieve road traffic congestion by using sea transport more extensively with a view toachieving sustainable mobility. To this end, the use of conventional, fast conventional and high-speed vessels in multimodal transport wasexamined. However, the above objective should not be achieved by the competition of sea transport with railway transport. Instead, thesemodes must capture part of the road transport share. It must also be clear that no direct competition exists between maritime and roadtransport but rather the need for both to be complementary.

En aquesta tesi doctoral es fa un estudi de tres possibles alternatives al procés tradicional de píquel-curtició, els principals inconvenients del qual són l'elevat consum d'aigua i la generació d'un gran volum d'aigües residuals. Les alternatives propostes aconsegueixen incidir positivament en ambdós factors, per la qual cosa la càrrega contaminant final és molt menor. / En esta tesis doctoral se hace un estudio de tres posibles alternativas al proceso tradicional de píquel-curtición, cuyos principales inconvenientes son el elevado consumo de agua y la generación de un gran volumen de aguas residuales. Las alternativas propuestas consiguen incidir positivamente en ambos factores, por lo que la carga contaminante final es mucho menor.

Els ports de mar constitueixen una infraestructura molt important en els països costaners, tant des del punt de vista econòmic com social. Però a la vegada són sistemes molt complexes des del punt de vista ambiental, ja que poden crear impactes significatius sobre l'entorn, magnificats sovint per la seva habitual proximitat a nuclis urbans. Per tant, l'equilibri entre la conservació del medi costaner i la continuïtat de les activitats antròpiques en aquesta zona és força difícil d'aconseguir. En aquesta tesi han estat identificats els principals impactes ambientals generats per l'activitat portuària (emissions a l'aigua, a l'aire, soroll, etc.), destacant de forma especial l'impacte ambiental accidental. El primer pas per tal de minimitzar aquests impactes és dur a terme una gestió adequada dels aspectes ambientals. Per això, s'han analitzat les metodologies existents en el camp de la gestió ambiental en ports, i s'ha arribat a la conclusió que existia la necessitat de crear una metodologia específica per avaluar la gestió ambiental en ports de mar. La metodologia desenvolupada consta de dues eines, per una banda el mètode d'autodiagnosi ambiental (SDM) per avaluar l'estat de la gestió ambiental en ports i, per altra, el mètode per a identificar i valorar aspectes ambientals significatius (SOSEA).L'SDM s'estructura en forma de qüestionari i cobreix els principals requeriments dels estàndards ambientals pel que fa a la gestió ambiental (ISO 14001 i EMAS). Permet identificar els punts forts i febles de la gestió que es duu a terme, tenir la referència dels ports europeus i fixar mesures de millora ambiental.El SOSEA es basa en l'aplicació d'una matriu activitats/aspectes, un qüestionari i una llista de comprovació. A partir de la informació obtinguda en aquests apartats es pot identificar els aspectes ambientals més importants i avaluar com s'està duent a terme la seva gestió.Aquestes eines han estat desenvolupades en el marc del projecte europeu ECOPORTS (2002-2005) i, per al seu disseny i prova, s'ha treballat amb estreta col·laboració amb els ports europeus. Finalment, ambdues eines han estat aplicades a un grup de ports (Goteborg, Barcelona, Gènova, Rotterdam, etc.) i s'ha pogut veure que els resultats de la seva aplicació han estat clarament positius, tant pel que fa a la seva acceptació com a la seva utilitat. / The sea ports are very important for the coastal areas, not only from the economic point of view but also from the social one. But at the same time, they are very complex systems from the environmental point of view since the port activities may create significant impacts on the environment and also disturb the nearby urban areas. So, the equilibrium between nature conservation and port activities in this area is quite difficult to attain.The main environmental impacts created by the port activities (water emissions, air emissions, dust, etc.) have been identified in this thesis, stressing in an important way the accidental (environmental) impact.The first step in order to minimize such impacts is to undertake an adequate management of the environmental issues. In this sense, the main environmental management initiatives in port have been described, concluding that it was necessary to develop a new methodology to assess the environmental management in sea ports.The methodology developed consists of two tools, on one hand the self diagnosis method (SDM) to assess the situation of the environmental management in ports and on the other hand the strategic overview of significant environmental aspects (SOSEA) to identify and assess the significant environmental aspects.SDM is a questionnaire where the main sections required for the implementation of an environmental management system are represented. It also follows the main requirements of ISO 14001. SDM feedback allows the ports to identify the strengths and weaknesses, to compare the results with the European Benchmark and to set up measures for the environmental improvement. SOSEA is based on the application of a matrix of activities/aspects, a questionnaire and a checklist. From the information gathered in these sections it is possible to identify the significant environmental aspects and assess their management. These tools have been developed in the frame of ECOPORTS project (2002-2005), funded by the European Union. For the design and test of the tools a very close collaboration with ports has been carried out.Finally, both tools have been applied to a group of ports (Gothenburg, Barcelona, Genoa, Rotterdam, etc.) and the results of their application have been clearly positive, not only for the good acceptance of the tools but also for their utility.

The aim of this thesis is to modify flax pulp fibres (Linum usitatissimum) by more friendly environmental processes. Pulp and paper research is focussing through enzyme systems investigation for developing green chemistry technologies due to existing environmental concerns and to legal restrictions. Moreover, it exists also an increasing strategic interest in using flax fibres to obtain high-quality specialty papers. That is why we study the application of biotechnology as an efficient alternative to traditional industrial processes based on the use of chemical agents. This work is framed by two of the main research topics of the Paper and Graphic Specialty Laboratory in the Textile and Paper Engineering Department of the Universitat Politècnica de Catalunya. One research line is based on pulp bleaching and is focused basically on the study of enzymatic systems as biobleaching agents; the other research topic that has been recently introduced in our investigation group is the use of enzymes as functionalisation agents by promoting the grafting of several compounds. Laccase is the main enzyme used in this thesis; it is an oxidoreductase that can assist reactions in an eco-friendly way since laccase uses air and produces water as the only by-product. Moreover, laccase can work under mill conditions and has wide application potential. The first part of this thesis involved the use of enzymes to bleach flax pulp. The aim was to explore the potential of various natural mediators (lignin-derived compounds) for delignifying flax fibres in order to identify the most efficient and ecofriendly choice among them. Afterwards, we assessed the use of various enzyme delignification stages in an industrial bleaching sequence. The ensuing totally chlorine free (TCF) sequence comprised various laccase-mediator system treatments (L stage) followed by a by a chelating stage (Q stage) and a subsequent bleaching step with hydrogen peroxide (Po stage). A xylanase pretreatment was additionally carried out. Laccases used came from the fungi Pycnoporus cinnabarinus and Myceliophthora thermophila; the performance of several natural mediators was compared with the obtained with the application of various synthetic mediators. In addition, the lack of studies on the properties of effluents from the treatment of non-wood pulp with laccase and natural mediators led A-1 A-2 us to examine effluent properties upon biotreatments and after different bleaching stages. The results obtained warrant upscaling any of the biobleaching sequences for flax pulp as they provide sustainable flax fibre with a high cellulose content and brightness above 80% ISO. The use of xylanase pretreatment was found to efficiently remove HexA and enhance delignification by laccase.

La tesi que ens ocupa, parteix de I'interes de blanquejar pasta kraft d'eucaliptus a traves de tecnologies netes, es a dir, utilitzant metodes mes respectuosos pel medi ambient. La motivacio per a la realitzacio d'aquesta tesi, sorgeix de la problematica ambiental ja coneguda que existeix amb relacio a la contaminacio produida pels reactius utilitzats en el blanqueig de pastes per a paper i de I'interes estrategic que representa per Espanya la utilitzacio de la fusta d'eucaliptus. D'aquesta manera, es volen estudiar nous sistemes enzimatics que puguin deslignificar i blanquejar aquesta pasta.La present tesi s'emmarca dins d'una de les linees d'investigacio del Departament d'Enginyeria Textil i Paperera, de la Universitat Politecnica de Catalunya, encaminada a ('Aplicacio de la Biotecnologia per al Blanqueig de Pastes.Aixi, s'enfoca la recerca cap a la utilitzacio de xilanases per a potenciar el blanqueig en sequencies ECF i TCF, i cap a la utilitzacio de lacases a traves del sistema lacasa-mediador per a blanquejar i deslignifcar la pasta. Degut al gran contingut en acids hexenuronics de les pastes kraft d'eucaliptus, i a la creixent importancia d'aquests en els processos de blanqueig, especial interes es dona en la seva evolucio al Ilarg dels diferents tractaments.Primerament es realitza un escrutini d'actuacio de diferents xilanases tant noves com comercials per tal d'identificar les mes eficients en potenciar el blanqueig. Aquests assajos es realitzen sobre sequencies XD, XP i XDP. Segons les propietats de la pasta d'index kappa, blancor, viscositat i HexA i segons I'analisi per cromatografia en capa fina dels efluents de I'etapa X, s'obte que la xilanasa comercial Xc i que la xilanasa nova XG son les mes eficients en potenciar el blanqueig. La xilanasa nova mes eficient pertany a la familia 11 de les glicosil hidrolases. D'altra banda, s'observa que la xilanasa XJ (familia 5) produeix Ileugers efectes sobre les pastes i que totes les xilanases noves (families 10, 11 i 5) contribueixen a la disminucio del contingut en HexA de les pastes.Seguidament, la millor xilanasa comercial (Xc) i nova (XG) s'apliquen en una sequencia complerta de blanqueig XDEopD1. Degut a I'interes cientific que representa aplicar per primera vegada una xilanasa de la familia 5 sobre les pastes, tambe s'aplica la xilanasa Xj en aquesta sequencia complerta. La xilanasa Xj s'aplica sola i combinada amb la xilanasa XG. Els resultats demostren que amb un pretractament amb xilanasa es milloren les propietats de les pastes al Ilarg de la sequencia i que el pretractament X podria permetre un estalvi en dioxid de clor. A mes, les xilanases no afecten a les propietats fisiques finals dels papers.En segon Iloc, s'aplica el sistema lacasa-mediador (L) sobre les pastes utilitzant HBT com a mediador. L'objectiu d'aquest tractament es d'una banda optimitzar les condicions d'aplicacio del sistema lacasamediador segons les propietats d'index kappa i blancor i d'altra banda veure si el pretractament amb xilanasa es capag de potenciar I'efecte del tractament L. Tambe es vol analitzar com el tractament L afecta als HexA, a la lignina i a la viscositat. Els resultats demostren que a dosis baixes de mediador i a temps curts s'obtenen bones propietats. El tractament L disminueix sobretot la lignina de la pasta tot i que tambe fa disminuir els HexA, i Ileugerament la viscositat. Els esterols de la pasta son tambe eliminats durant aquest tractament. A mes, es demostra que el pretractament X "facilita" I'efecte del sistema lacasa-mediador en eliminar els acids hexenuronics de la pasta. Per I ltim, queda reforgada la necessitat d'aplicar una etapa d'extraccio alcalina posterior a L.Posteriorment, es compara I'efectivitat del mediador NHA respecte I'HBT obtenint resultats molt prometedors amb aquest mediador ja que a part de ser mes barat i potencialment menys toxic que I'HBT, presenta una reaccio de tipus reversible i es tant eficient com aquest I ltim en deslignificar la pasta. Paral·lelament es realitza una recerca de mediadors naturals produits durant el creixement de P.cinnabarinussobre la fusta de pi. Per I ltim, s'aplica per primera vegada la tirosinasa en el blanqueig de pastes i els resultats indiquen que cal continuar la recerca sobre aquesta possible aplicacio biotecnolOgica d'aquest enzim. Aquest bloc d'experiencies s'ha realitzat a l'"Institut National de la Recherche Agronomique" (INRA) de Marsella, Franca.Finalment, es discuteix sobre la importancia dais acids hexenuronics al Ilarg dais processos de blanqueig, i sobre com aquests son eliminats pals diferents tractaments tant quimics corn enzimatics. Es troba la relacio antra aquests acids i I'index kappa de la pasta d'eucaliptus utilitzada.