http://hdl.handle.net/2117/3155 2013-05-24T18:56:27Z http://hdl.handle.net/2117/18720 Title: Fuzzy model for risk assessment of persistent organic pollutants in aquatic ecosystems Authors: Seguí, Xavier; Pujolasus, Edgar; Betrò, S.; Agueda Costafreda, Alba; Casal Fàbrega, Joaquim; Ocampo-Duque, W.; Rudolph, I.; Barra, R.; Páez, M.; Barón, E.; Eljarrat, E.; Barceló, D.; Darbra Roman, Rosa Maria Abstract: We developed a model for evaluating the environmental risk of persistent organic pollutants (POPs) to aquatic organisms. The model is based on fuzzy theory and uses information provided by international experts through a questionnaire. It has been tested in two case studies for a particular type of POPs: brominated flame retardants (BFRs). The first case study is related to the EU-funded AQUATERRA project, with sampling campaigns carried out in two Ebro tributaries in Spain (the Cinca and Vero Rivers). The second one, named the BROMACUA project, assessed different aquatic ecosystems in Chile (San Vicente Bay) and Colombia (Santa Marta Marsh). In both projects, the BFRs under study were polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). However, the model can be extrapolated to other POPs and to different aquatic ecosystems to provide useful results for decision-makers. 2013-04-09T10:14:39Z http://hdl.handle.net/2117/17273 Title: A dispersion safety factor for LNG vapor clouds Authors: Vílchez Sánchez, Juan Antonio; Villafañe, Diana; Casal Fàbrega, Joaquim Abstract: The growing importance of liquefied natural gas (LNG) to global energy demand has increased interest in the possible hazards associated with its storage and transportation. Concerning the event of an LNG spill, a study was performed on the relationship between the distance at which the lower flammability limit (LFL) concentration occurs and that corresponding to the visible contour of LNG vapor clouds. A parameter called the dispersion safety factor (DSF) has been defined as the ratio between these two lengths, and two expressions are proposed to estimate it. During an emergency, the DSF can be a helpful parameter to indicate the danger of cloud ignition and flash fire 2013-01-11T10:01:31Z http://hdl.handle.net/2117/17232 Title: Jet fires: a "minor" major accident? Authors: Casal Fàbrega, Joaquim; Gómez-Mares, Mercedes; Muñoz, Miguel Angel; Palacios, Adriana Abstract: Jet fires have received only a rather reduced attention as compared to other types of fires; this is probably due to the fact that they are usually much smaller that fireballs, pool fires or tank fires. However, jet fires often occur in areas where there is other equipment and the probability of flames impinging on a pipe or a vessel can be high. Furthermore, due to the turbulence of the phenomenon, the combustion in such fires is very good and high heat fluxes can seriously affect this equipment, thus originating a domino effect which will enlarge the scale of the accident. A historical survey has shown that, of the jet fires reported in accident data bases, 50 % caused another event with severe effects. In 90 % of the domino effect cases there was an explosion, usually of a vessel; this was especially frequent in transportation accidents. In this communication the main features of jet fires are commented: most frequent domino effect sequences, shape and size, thermal behaviour, mathematical modelling. 2013-01-09T12:11:57Z http://hdl.handle.net/2117/17053 Title: Assessment of the shape of vertical jet fires Authors: Palacios, Adriana; Casal Fàbrega, Joaquim Abstract: Experiments were carried out on relatively large vertical propane sonic and subsonic exit velocity jet fires (up to approximately 10 m in length and 1.5 m in width). The main geometrical features of jet fires (flame shape, length and width) were determined by analyzing infrared images. From the observations of visible and infrared images, the flame boundary was defined as that corresponding to a temperature of 800 K. Results were compared with the shapes proposed in previous research projects. In the present study, data for sonic and subsonic exit velocity flames indicated that a cylindrical shape could accurately describe the shape of a vertical propane jet fire in still air. The length of such a cylindrical jet fire was the radiant flame length and the equivalent diameter was that corresponding to a volume equal to that surrounded by the aforementioned boundary. The ratio of flame length to diameter was found to be 7. Expressions are proposed to predict the values of jet flame length and width as a function of orifice exit diameter and Reynolds number. 2012-11-30T08:59:13Z http://hdl.handle.net/2117/17052 Title: Design optimization of hazardous substance storage facilities to minimize project risk Authors: Bernechea, Esteban; Arnaldos Viger, Josep Abstract: The storage of dangerous substances is a high risk procedure: a historical analysis revealed that 17% of the major accidents associated with the chemical industry are related to this process. When a storage facility is designed, the investment in safety is not always optimal. The safety measures that are applied are sometimes redundant or ill-maintained. One way to improve safety in a storage facility would be to take advantage of the fact that dividing the mass of dangerous substance results in less catastrophic accidents. In this paper, we present a new method for optimizing the design of storage plants and minimizing the risk by calculating the ideal number of tanks and improving the way in which money is invested in safety. This is achieved by redefining how to estimate risk and by applying the principles of mathematical optimization to quantitative risk analysis. The method is explained step by step. We also present two case studies and a validation of the method using risk analysis software and iso-risk curves. 2012-11-30T08:45:10Z http://hdl.handle.net/2117/16755 Title: Risk analysis active learning through the investigation of real cases Authors: Darbra Roman, Rosa Maria; Casal Fàbrega, Joaquim; Pastor Ferrer, Elsa; Vílchez Sánchez, Juan Antonio; Arnaldos Viger, Josep; Planas Cuchi, Eulàlia Abstract: Risk analysis is a topic of high relevance in chemical engineering. Courses on this topic are being introduced increasingly into the university curricula. The investigation of real cases is an interesting opportunity to consolidate the concepts taught in such courses and to get a better engagement of students through a creative work. The exercise proposed in this paper has to be performed by a group of students to whom a set of information has been provided. In the exercise, the students play the role of an expert team: they have to deliver a final report including diverse sections such as the description of the accident, the explanation of why and how it occurred, different calculations and finally, some conclusions. From the pedagogical point of view, the results obtained from this type of exercise are very positive and promote the students active and cooperative learning. 2012-10-19T08:28:49Z http://hdl.handle.net/2117/16754 Title: Fuzzy logic based risk assessment of effluents from waste-water treatment plants Authors: Cabanillas, Julián; Ginebreda, Antoni; Guillén, Daniel; Martínez, Elena; Barceló, Damià; Moragas, Lucas; Robusté, Jordi; Darbra Roman, Rosa Maria Abstract: This paper presents a new methodology to assess the risk of water effluents from waste-water treatment plants (WWTPs) based on fuzzy logic, a well-known theory to deal with uncertainty, especially in the environmental field where data are often lacking. The method has been tested using the effluent's pollution data coming from 22 waste-water treatment plants (WWTPs) located in Catalonia (NE Spain). Thirty-eight pollutants were analyzed along three campaigns performed yearly from 2008 to 2010. Whereas 9 compounds have been detected in more than 70% of the samples analyzed, 7 compounds have been found at levels equal or higher than the river Environmental Quality Standards set by the Water Framework Directive. Upon combination of both criteria (presence and concentration), compounds of greatest environmental concern in the WWTP studied are nickel, the herbicide diuron, and the endocrine disruptors nonyl and octylphenol. It is remarkable the low variability of the pollutant concentration just differing for the case of nickel and zinc. These low values of exposure together with other pollutants' characteristics provide a medium or low risk assessment for all the WWTPs. The results of this new method have been compared with COMMPS procedure, a solid method developed in the context of the Water Framework Directive, and they show that the fuzzy model is more conservative than COMMPS. This is due to different reasons: the fuzzy model takes into account the persistence of chemical compounds whereas COMMPS does not; the fuzzy model includes the weights provided by an expert group inquired in previous works and also considers the uncertainty of the environmental data, avoiding the crisp values and offering a range of overlapping between the different fuzzy sets. However, the results even if being more conservative with fuzzy logic, are in good agreement with a solid methodology such as the COMMPS procedure. 2012-10-19T08:16:59Z http://hdl.handle.net/2117/16493 Title: Risk-based optimization of the design of on-shore pipeline shutdown systems Authors: Medina, Héctor; Arnaldos Viger, Josep; Casal Fàbrega, Joaquim; Bonvicini, Sarah; Cozzani, Valerio Abstract: Crude oil and other liquid materials are transported in large quantities through pipelines. Pipelines are an efficient and safe transport way as compared to both rail and road transportation, both from the economical and environmental points of view. Nevertheless, loss of containment accidents can occur due to external action ea mechanical impact, for examplee or to corrosion, aging, etc. Even though the frequency of such events is certainly very low, the effects and consequences on environment can be very important. The consequences of accidents in pipelines can be efficiently reduced through a suitable design of the whole system. One of the points which must be decided in the design is the installation of blocking valves at appropriate distances, so that emergency shutdowns can interrupt the flow of substance and isolate the section where the loss of containment has taken place. In the case of pipe rupture the amount released is therefore limited to the content between two consecutive valves, usually placed according to heuristic criteria. However, if too many valves are used, the capital cost of equipment increases excessively, and if too few are used, the risk of serious accidents increases. In this paper we consider the possibility of improving the design of such systems by applying riskbased optimization criteria. We propose an optimization methodology to solve this conflict by means of an objective function that analyzes the variations in overall costs, including the cost of the investment (with specific reference to blocking valves) and the cost of accidents. The result is an optimum situation in which costs are kept to a minimum. As an example, we apply the methodology to the transportation of gasoline by pipeline. 2012-09-14T11:08:24Z http://hdl.handle.net/2117/16377 Title: Aerial fire suppression evaluation grains effectiveness Authors: Pastor Ferrer, Elsa; Plucinski, Matt; Planas Cuchi, Eulàlia 2012-07-31T09:44:40Z http://hdl.handle.net/2117/15895 Title: Thermal radiation from vertical jet fires Authors: Palacios, Adriana; Muñoz, Miguel; Darbra Roman, Rosa Maria; Casal Fàbrega, Joaquim Abstract: Geometric and thermal data, obtained from a series of large outdoor jet fire experiments, were used to estimate the thermal radiation intensity from the flames towards targets located at diverse distances. Vertical turbulent sonic and subsonic exit velocity propane jet fires, up to 10.3 m in length released in still air, were studied. The temperatures of the flame surface and the surface emissive power of the flame were also analysed by processing infrared images. Thermal radiation intensity was estimated by applying the solid flame model in both one-zone and multiple-zone configurations (taking into account the variation of surface emissive power), considering the flame as a cylinder defined by the 800 K isotherm. Experimental and predicted thermal radiation intensity values were compared. 2012-05-18T11:12:27Z http://hdl.handle.net/2117/14513 Title: Investigación en incendios forestales: quemas experimentales en Australia Authors: Agueda Costafreda, Alba; Cubells, Miquel; Pastor Ferrer, Elsa; Pérez, Yolanda; Planas Cuchi, Eulàlia Abstract: En este trabajo se muestra un ejemplo de lo que se está haciendo actualmente desde el mundo de la investigación para contribuir en la mejora del conocimiento que se tiene del comportamiento de los incendios forestales. Se describen las quemas experimentales que se llevaron a cabo en bosques de eucalipto de Australia durante el mes de marzo de 2008 y en las cuales miembros del Centre d’Estudis del Risc Tecnològic (CERTEC), de la Universitat Politècnica de Catalunya (UPC), participaron activamente. Éstas son las quemas experimentales más grandes que hasta la fecha se han llevado a cabo a nivel mundial. Algunos resultados que se pueden extraer de este tipo de experimentación se ponen de relieve en este trabajo. Más específicamente, se describe una metodología que permite cuantificar la efectividad de las descargas de productos químicos (retardante a largo plazo, gel y espuma) a partir del análisis de imágenes infrarrojas captadas desde el aire. 2012-01-13T10:46:02Z http://hdl.handle.net/2117/14321 Title: Computing forest fires aerial suppression effectiveness by IR monitoring Authors: Pérez, Yolanda; Pastor Ferrer, Elsa; Planas Cuchi, Eulàlia; Plucinski, M; Gould, G Abstract: This paper describes the methodology developed to analyse IR images obtained during the aerial suppression experiments that were conducted in Ngarkat Conservation Park, South Australia, on 3–5 March 2008. This methodology has been specifically developed in order to extract the maximum information from the IR images taken from an observing helicopter, in those tests where chemical suppressants are applied directly on the fire, although it could eventually be applied to other similar situations. The information obtained after applying this methodology allows quantifying the aerial suppression effectiveness. 2011-12-27T10:35:53Z http://hdl.handle.net/2117/14182 Title: Convective heat transfer around vertical jet fires: an experimental study Authors: Kozanoglu, Bulent Kozanoglu; Zárate López, Luis; Gómez-Mares, Mercedes; Casal Fàbrega, Joaquim Abstract: The convection heat transfer phenomenon in vertical jet fires was experimentally analyzed. In these experiments, turbulent propane flames were generated in subsonic as well as sonic regimes. The experimental data demonstrated that the rate of convection heat transfer increases by increasing the length of the flame. Assuming the solid flame model, the convection heat transfer coefficient was calculated. Two equations in terms of adimensional numbers were developed. It was found out that the Nusselt number attains greater values for higher values of the Rayleigh and Reynolds numbers. On the other hand, the Froude number was analyzed only for the subsonic flames where the Nusselt number grows by this number and the diameter of the orifice. 2011-12-07T13:04:43Z http://hdl.handle.net/2117/14181 Title: Report on the 1st Workshop of the RISKCYCLE Coordination Action. Hanoi, Vietnam, 4-5 May 2010 Authors: Billitewski, Bernd; Barceló, Damià; Darbra Roman, Rosa Maria; Van der Voet, Ester; Mohammed, Belhaj; Benfenati, Emilio; Ginebreda, Antoni; Grundmann, Veit Abstract: This Workshop on “Safety assessment of consumer goods coming from recovered materials in a global scale perspective” is the first of the Thematic Workshops organized within the framework of the European Union (EU)-funded Coordination Action “Risk-based management of chemicals and products in a circular economy at a global scale” (RISKCYCLE). It was organised by the Dresden University of Technology (TUD), coordinator of the project, and by the Hanoi University of Science (HUS). The workshop was held from 4th–5th May 2010 in Hanoi, Vietnam 2011-12-07T12:39:12Z http://hdl.handle.net/2117/14089 Title: Recerca en incendis forestals: cremes experimentals a Austràlia Authors: Planas Cuchi, Eulàlia; Pastor Ferrer, Elsa; Pérez, Yolanda 2011-11-28T10:03:08Z