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  • Historical evolution of process safety and major-accident hazards prevention in Spain. Contribution of the pioneer Joaquim Casal.

     Planas Cuchi, Eulalia; Arnaldos Viger, Josep; Darbra Roman, Rosa Maria; Muñoz Messineo, Miguel Angel; Pastor Ferrer, Elsa; Vílchez, Juan Antonio
    Journal of loss prevention in the process industries
    Date of publication: 2014-04-11
    Journal article

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    This paper aims at presenting the evolution of process safety in Spain from various points of view. In first place, a study of the accidents occurred in this country in the process industry and in the transportation of chemical substances is presented. After this, the starting point of the process safety research in Spain and its evolution during the years are explained. The importance of this topic has also been reflected in the chemical engineering studies in some Spanish universities. Therefore, the current status of the studies on process safety in Spain is analyzed in this paper. A section has also been devoted to the process safety in the Spanish industry. An analysis of the related legislation and its implementation in the Spanish process industry is also presented in this paper. Finally, the professional career of Prof. Joaquim Casal, the pioneer in Spain in process safety and risk assessment, is summarized.

  • Wildfire behaviour and danger ratings

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date of publication: 2013-04
    Book chapter

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    This chapter provides an overview of wildland fire behaviour and danger rating systems, the understanding of which allows for better estimates of the contribution that fire plays in the Earth system. Fire dynamics are controlled by multiple factors, the most important being biomass characteristics and atmospheric and topographical conditions under which the fire is spreading. The study and characterization of these factors and their link to fire behaviour has allowed the researchers in this field to develop mathematical models for fire behaviour prediction, classify vegetation types and define vegetation models that can provide information on how the fire will behave in such fuels, and forecast fire danger in order to be able to design and undertake preventive actions.

  • Modelos de combustible para caracterizar el comportamiento de los incendios en regenerados clareados de pino carrasco

     Domènech Jardi, Rut; Pastor Ferrer, Elsa; Àgueda Costafreda, Alba; Sans Català, Ariadna; Navascués Ramos, Pablo; Planas Cuchi, Eulalia
    Montes
    Date of publication: 2013-12-23
    Journal article

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  • Modelos de combustible para caracterizar el comportamiento de los incendios en regenerados clareados de pino carrasco

     Domènech, Rut; Pastor Ferrer, Elsa; Àgueda Costafreda, Alba; Sans Català, Ariadna; Navascués Ramos, Pablo; Planas Cuchi, Eulalia
    Montes
    Date of publication: 2013
    Journal article

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  • Estudio de la dispersión e incendio de nubes inflamables de gas (GNL y GLP)  Open access

     Villafañe Santander, Diana
    Defense's date: 2013-06-20
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    This thesis is focuses on the study of the dispersion and combustion of a vapor cloud resulting from the escape of LNG and LPG. The consumption of natural gas and LPG is clearly growing, and is based on multiple storage facilities and different types of transport. The possibility of a release and the subsequent vapor cloud formation is significant. The application of appropriate measures to ensure safety in terminals and facilities related to these products is essential to the community safety. An important aspect is the management of the emergency once the cloud has reached the stationary state (the time to reach this state depends on wind velocity, but is usually very short). In this situation, any information about the position of the flammable region of the cloud can be very helpful. A historical analysis of accidents involving vapor cloud fires has been carried out. 176 accidents have been analyzed, which have yielded information on the causes, origins and consequences of such events. A dispersion safety factor (DSF) has been proposed as a tool to help in the decision process under these circumstances. The parameter DSF is the ratio between the distance reached by the lower flammability limit and that of the visible cloud. The results obtained for the dispersion safety factor with the DEGADIS code agree fairly well with the evidence from experimental data obtained at large scale. This factor is strongly dependent on the atmospheric relative humidity. Thus, when high relative humidity prevails, the cloud will be visible for some distance beyond the flammable region (DSF < 1). When the relative humidity in the air is low, the flammable region extends beyond the visible cloud contour (DSF > 1). In this case, the flammable vapor cloud will not be visible at the location of any potential ignition source. Two expressions have been proposed to estimate the parameter DSF for a release of LNG according to the range of HR. The same treatment has also been applied to the case of a spill of liquefied propane gas cooled at atmospheric pressure. With respect to the combustion of the flammable vapor cloud, a new expression has been obtained, which determines the flame speed as a function of the wind speed, based on various large scale tests conducted with LNG between 1968 and 1982; this expression gives a better fit for high wind speeds. A relatively simple model of the flash fire has been developed based on the dispersion of the cloud as a function of fuel properties and atmospheric conditions (stability and wind velocity). The size of the flames will depend on the size of the cloud, being higher that the latter. It has been observed from the available data experiments, that the flame height increases proportionally to the visible cloud.

  • Infrared imagery on wildfire research. Some examples of sound capabilities and applications.

     Pastor Ferrer, Elsa; Planas Cuchi, Eulalia
    International Conference on Image Processing Theory, Tools and Applications
    Presentation's date: 2012-10
    Presentation of work at congresses

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    Wildfire infrared monitoring is nowadays applied to different problems related to fire prevention, fire suppression and fire behaviour analysis. In terms of research, infrared thermography offers unique capabilities although it is constantly challenging the scientific community to develop sound process imagery methodologies in order to obtain valuable and reliable information about fire phenomena. In this paper we show some infrared thermography applications that we have recently developed to provide solutions on fuel mapping, fire behaviour analysis, fire suppression and fire effects assessment. We highlight the advantages and drawbacks of all of them and present future problems that can be tackled with this type of fire monitoring techniques.

  • Aerial fire suppression evaluation grains effectiveness

     Pastor Ferrer, Elsa; Plucinski, Matt; Planas Cuchi, Eulalia
    Wildfire
    Date of publication: 2012-07
    Journal article

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  • Risk analysis active learning through the investigation of real cases

     Darbra Roman, Rosa Maria; Casal Fabrega, Joaquim; Pastor Ferrer, Elsa; Vílchez, Juan Antoni; Arnaldos Viger, Josep; Planas Cuchi, Eulalia
    Process safety and environmental protection
    Date of publication: 2012
    Journal article

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    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.

  • Air infiltration in Catalan dwellings and sealed rooms: An experimental study

     Montoya Rodríguez, María Isabel; Pastor Ferrer, Elsa; Planas Cuchi, Eulalia
    Building and environment
    Date of publication: 2011-10
    Journal article

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    In this study, we performed a series of trials to measure the infiltration air exchange rate (ACH) of several single-family dwellings throughout Catalonia, as well as the ACH of sealed rooms that could be used as indoor shelters. A shelter is an indoor room where people can take protection in case of a toxic gas release, while the toxic cloud passes through the dwelling. Experimental measurements were made using the tracer gas decay technique with CO2 as the tracer gas in 2 periodsdsummer and winterdwith the aim of characterizing air infiltration in Catalan dwellings. The geometric means obtained for the ACH of shelters and dwellings were 0.16 and 0.23 h-1, respectively, that is, lower than those reported for North American (0.56 h-1) and Greek (0.76 h-1) dwellings. In general, the ACH was lower for shelters than for dwellings, and the average reduction btained in shelters with respect to dwellings was 35%. The largest reductions were obtained in old dwellings with small floor areas and few stories. As for meteorological conditions, we found that the ACH of dwellings was more closely linked to wind speed than indoore-outdoor temperature difference, while the ACH of shelters was more affected by indoore-outdoor temperature and temperature differences inside the dwelling, particularly in dwellings with 3 or more stories.

  • Different approaches for the head fire perimeter definition in wildland fires

     Planas Cuchi, Eulalia; Cubells, M; Pastor Ferrer, Elsa
    International IAFSS Symposium
    Presentation's date: 2011-06
    Presentation of work at congresses

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  • Investigación en incendios forestales: quemas experimentales en Australia

     Àgueda, Alba; Cubells, Miquel; Pastor Ferrer, Elsa; Pérez, Yolanda; Planas Cuchi, Eulalia
    Boletin informativo CIDEU
    Date of publication: 2011
    Journal article

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    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.

  • L'estat actual de la modelització computacional d'incendis

     Planas Cuchi, Eulalia
    Recull d'artícles. Seguretat en espais i edificis públics.
    Date of publication: 2011
    Journal article

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  • Efectivitat dels tractaments d'aclarida en la reducció del risc de propagació d'incendis en regenerats de pi blanc  Open access

     Domènech Jardí, Ruth
    Defense's date: 2011-11-18
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Increased wildfire activity over the last years has made fire managers to become more concerned about the effectiveness of current fuel treatment practices to reduce fire risk and severity. Fuel treatments lead to changes in the forest structure and therefore modify certain basic parameters that may influence the fire behaviour. The goal of this work is to quantitatively assess the effectiveness of fuel treatments in reducing risk of wildfires spread in some typically Mediterranean forest. Specifically, it envisages to know the characteristics of the fire that can occur in the slash originated from regenerated aleppo pine stands that were thinned after a wildfire and also to know the evolution of slash combustibility after the treatment. First, an extensive literature review has been done, focused mainly on those works that assessed the effectiveness of fuel treatments in reducing the risk of wildfire. Several studies demonstrated the effectiveness of treatments such as prescribed burning or thinning. However, these studies are not consistent about what treatment and slash management technique are the most effective. A study area has been selected and located within the perimeter of a large forest fire occurred in Bages (Central Catalonia, Spain) in 1994 to study the effectiveness of a type of fuel treatment usually performed in the Mediterranean Basin. The site was previously thinned during different periods and the slash was left in, not managed. In this area, the fuel, environment and topographic characteristics have been determined. With the fuel sampling methods used at the site, a protocol has been produced in order to characterize the regenerated aleppo pine stands, useful to obtain the parameters needed to evaluate fire behaviour. Results have led to a new fuel model for regenerated aleppo pine stands and also fuel models for regenerated aleppo pine stands that have been thinned at different times with the slash remaining unmanaged at the site. An experimental burning program has been implemented reproducing two different regenerated structures (6 and 40 months after treatment). With these experiments it has been proved that ex-situ experimentation is not useful to reproduce actual fire situations because it is impossible to repeat faithfully the overall structure of the ecosystem that affect fire behavior. A series of simulations of potential fires that could occur in the study area have been performed, incorporating the determined inputs (environmental conditions and fuel type) and evaluating different simulation tools (NEXUS i WFDS). Results obtained with the two simulations tools used confirm that both tools are reliable. In general values obtained in fireline intensity and rate of spread with WFDS are larger than with NEXUS. Results from simulations of Bages plots carried with both simulation tools generally show that fire behavior is more severe 1 month and 6 months after the treatment. That is, the wildfire effects after the treatment would be worse than in the untreated control plot and that time does not improve this situation, at least six months after treatment. According to the results and given the characteristics of our country where the risk of fires is very high, the effect of thinning treatments performed in central Catalonia after the 1994 fire brings a great fire vulnerability in treated stands, at least during the first months of treatment.

  • Summary of first outcomes

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-02-07
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial fire fighting. This document summarizes the work done by CERTEC between the 13th January and 7th February 2011 concerning the project “Elaboración de una version preliminary de una metodología CDM-NM para la reducción de emisiones mediante la extinction aérea de incendios forestales”.

  • Emissions from fires and carbon balance

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-05
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial firefighting

  • Carbon balance in the study area

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-07
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial firefighting

  • Modelos para la estimación de la velocidad de propagación

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-09
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial firefighting

  • Distribución de los incendios en función de su tamaño

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-10
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial firefighting

  • Introduction to SIASim

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa
    Date: 2011-03
    Report

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    Document del projecte: Preliminary CDM-NM to reduce GHG emissions with aerial fire fighting.

  • DR-5. Avaluació de models de comportament d'incendis

     Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Domènech, Rut; Àgueda, A
    Date: 2011-06
    Report

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    Simulacions d'incendis en les diferents parcel·les d'estudi d'IRVA i de les cremes experimentals de Can Padró

  • DR-6. Focs experimentals exsitu

     Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Domènech, Rut; Àgueda, A.
    Date: 2011-04
    Report

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  • Access to the full text
    Recerca en incendis forestals: cremes experimentals a Austràlia  Open access

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa; Pérez, Yolanda
    Revista de tecnologia
    Date of publication: 2011-10
    Journal article

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  • Fire intensity reduction in straw fuel beds treated with a long-term retardant

     AGUEDA COSTAFREDA, ALBA; Pastor Ferrer, Elsa; Pérez, Yolanda; Viegas, Domingo Xavier; Planas Cuchi, Eulalia
    Fire safety journal
    Date of publication: 2011-01
    Journal article

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    The present paper reports fire intensity reduction factors in partially retardant-treated straw fuel beds. Propagation experiments were carried out in the laboratory with fuel beds with a bulk density of 7.5 kgm_3 under no-slope/no-wind, up slope/no-wind and no-slope/wind-aided conditions. Fire-Trol 931, along-term retardant based on polyphosphates, was employed in these experiments and a single retardant concentration of 0.2kg of dry retardant product per kg of fuel was tested. It has been statistically inferred that fire intensity reduction factors are constant, regardless of the fire intensity of the flame front at the untreated area of the fuel bed, and a mean fire intensity reduction factor of 0.80 has been computed under the experimental conditions tested.

  • Effect of additional measures when evaluating shelter in place effectiveness in the case of a toxic gas release

     Montoya Rodríguez, María Isabel; Planas Cuchi, Eulalia
    European Meeting on Chemical Industry and Environment
    Presentation's date: 2010-05-19
    Presentation of work at congresses

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  • Effect of wind and slope when scaling the forest fires rate of spread of laboratory experiments

     Pérez Ramirez, Yolanda; Pastor Ferrer, Elsa; AGUEDA COSTAFREDA, ALBA; Planas Cuchi, Eulalia
    Fire technology
    Date of publication: 2010-06-18
    Journal article

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    This paper uses the scaling laws obtained from a Froude Modeling perspective to analyze the variations experienced in the rate of spread of wind-aided and up-slope laboratory fires when changing the size of a scale model. The results have shown that the rate of spread scaling law is no longer verified when working at laboratory scale in steep slopes and high wind speed conditions. The paper also provides a framework for scaling and scale issues in forest fire research.

  • Pile burning of cutting debris in stands of hazel (Corylus avellana): An experimental study of smouldering combustion towards the validation of a burning protocol

     Pastor Ferrer, Elsa; Pérez Ramirez, Yolanda; AGUEDA COSTAFREDA, ALBA; Miralles, Marta; Planas Cuchi, Eulalia
    Fire safety journal
    Date of publication: 2010-01
    Journal article

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    Smouldering combustion in burning piles was experimentally investigated by studying temperature changes in six piles of 2 m of diameter of cutting debris of hazel (Corylus avellana) for three days after extinction. The piles were monitored using an IR camera and K-type thermocouples. The experiment was designed in order to study how the maximum temperature of the charcoal might be influenced by the individual and interaction effects of both the quality of extinction and the elapsed time until the start of extinction of the piles. The piles that were properly extinguished (i.e. using a high-pressure, homogeneously distributed water flow of 50 l/min for 4 min) had a uniform temperature profile and did not have significant hot spots. The temperature reached equilibrium with the environment in less than 10 h after extinction. In contrast, a smouldering front moved throughout the poorly extinguished piles, which had a wide temperature distribution and hot spots of up to 700 °C. A simulation of windy conditions after three days of experiments on a poorly extinguished pile showed that the reactivation of charcoal combustion was possible. It gave a high-risk scenario to cause a wildfire, with hot smouldering embers being transported by wind flow. The results are of interest to improve pile burning protocols so that the number of wildfires caused by such practices may be reduced.

  • Computing forest fires aerial suppression effectiveness by IR monitoring

     Pérez Ramirez, Yolanda; Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Plucinski, Matt; Gould, Jim
    Fire safety journal
    Date of publication: 2010-09-06
    Journal article

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  • Aplicación del Análisis de Riesgos a la Optimización de Plantas Industriales

     Medina, Héctor
    Defense's date: 2010-12-14
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Contribution to the assessment of shelter-in-place effectiveness as a community protection measure in the event of a toxic gas release  Open access

     Montoya Rodríguez, María Isabel
    Defense's date: 2010-11-26
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    En les darreres dècades el nombre d'accidents ocurreguts en la industria química i durant el transport de mercaderies perilloses ha augmentat substancialment, registrant-se en la seva majoria en zones densament poblades. Els núvols de gasos tòxics solen originar-se en aquests accidents i malgrat que són menys probables que altres tipus d'accidents, poden afectar grans extensions i contaminar zones poblades, provocant greus conseqüències. Això comporta un gran repte per a les autoritats civils, que han d'avaluar i decidir l'àrea que cal evacuar i l'àrea en la que s'ha d'implementar el confinament com a mesura de protecció. L'avaluació de l'efectivitat del confinament comprèn tres etapes fonamentals: el càlcul de la dispersió exterior, el càlcul de la concentració interior en funció de la concentració exterior i l'avaluació dels efectes adversos per a la salut. Aquesta tesi s'enfoca principalment en l'estudi de la segona etapa, la qual és funció de la taxa d'infiltració d'aire en les edificacions.Inicialment es va realitzar una extensa revisió bibliogràfica sobre les tres etapes, fent èmfasi en la cerca de models pel càlcul de la concentració interior, la taxa d'infiltració y l'hermeticitat de les vivendes. Posteriorment, a través d'una anàlisi de sensibilitat es trobà que la taxa de renovació d'aire té una gran influencia sobre l'efectivitat del confinament i, a més, atès que aquesta varia per cada edificació, el coneixement de la seva distribució en una població és necessari per a una avaluació adequada de l'efectivitat del confinament, ja que suposar-la constant per a totes les edificacions pot comportar sobreestimacions o subestimacions del radi d'evacuació. Per tant, amb la finalitat d'obtenir una aproximació de la distribució de l'hermeticitat, es va aplicar el model desenvolupat pel Lawrence Berkeley National Laboratory (LBNL), que prové de dades de vivendes nord-americanes, a les vivendes catalanes. De tota manera, els resultats obtinguts es trobaven esbiaixats a les zones climàtiques, essent les prediccions per a vivendes ubicades en zones seques més hermètiques que en zones humides. En el cas de Catalunya, on les tècniques constructives no varien significativament d'una zona a una altra i la majoria de vivendes estan construïdes a base de materials pesats, no és d'esperar una diferència tan marcada com la predita pel model del LBNL. Per tant, es va decidir desenvolupar un model per a les vivendes catalanes utilitzant la base de dades de taxes d'infiltració de vivendes unifamiliars del CETE de Lyon, ja que aquestes vivendes tenen més similitud amb les vivendes catalanes que no pas les nord-americanes.El model desenvolupat, denominat UPC-CETE, permet estimar l'hermeticitat de les vivendes unifamiliars en funció de l'àrea, el número de pisos, l'edat i el tipus d'estructura constructiva: lleugera o pesada. Els valors d'hermeticitat predits amb aquest model foren menors que els obtinguts amb el model del LNBL, tal com s'esperava. Finalment, per tal de validar i millorar el model desenvolupat, es van realitzar mesures de la taxa de renovació d'aire en diverses vivendes de Catalunya i també en habitacions prèviament condicionades per ser utilitzades com a refugi, per tal d'avaluar la reducció guanyada sobre la taxa de renovació de tota la vivenda. Com a mitjana, s'obtingueren reduccions d'un 35% i es trobà que les reduccions més grans tenien lloc en vivendes antigues, amb àrees petites d'una o dues plantes. El model UPC-CETE millorat a partir dels resultats obtinguts en les proves experimentals, s'incorporà a la metodologia per avaluar l'efectivitat del confinament en l'etapa d'estimació de la taxa de renovació d'aire, evitant l'ús d'un valor constant per a totes les vivendes i promovent així l'ús d'una distribució d'aquest paràmetre per secció censal afectada dins la població.

    During the last decades the number of accidents in chemical industries and during transportation of hazardous substances has significantly increased, with most of them occurring in highly populated areas. One of the possible accidents is a toxic gas cloud, which although less common than other major hazards could affect larger areas reaching populated zones and producing more severe consequences. This implies then, a great challenge to emergency managers who must plan and decide the areas where protection measures should be implemented: shelter in place and/or evacuation. The assessment of the effectiveness of shelter in place is subjected to three main stages: the calculation of the outdoor gas dispersion, the estimation of indoor concentration from outdoor concentration and the evaluation of human vulnerability. This thesis is mainly focused on the study of the second stage which is primarily a function of buildings leakage.Initially we performed a bibliographic survey with special interest on the models to estimate indoor concentration from outdoor concentration, airtightness of dwellings and ventilation models. Then, through a sensitivity analysis, we found that the air exchange rate has a great influence on the effectiveness of shelter in place. Moreover, since this parameter is different for each building, the knowledge of the distribution of this variable in the affected population would lead to a more accurate assessment of the effectiveness of shelter in place, because if we assume it as a fix value, constant for all buildings, over or underestimations of the evacuation radius may occur. Therefore, with the aim of making an estimation of the airtightness distribution in Catalunya, we applied the model developed by the Lawrence Berkeley National Laboratory (LBNL), a model based on data from North American dwellings, to Catalan dwellings. The results obtained were influenced by climate zones, due to the coefficients of the model, being more airtight the predictions for dwellings located in dry climates than for dwellings in humid zones. In the case of Catalunya, where constructions techniques do not differ significantly from one zone to another and most of the dwellings consist of a heavy structure, a difference such as that predicted by the model of the LBNL is not expected. Consequently, we decided to develop a model for Catalan dwellings using the air leakage database from the CETE de Lyon, since French dwellings are more likely to Catalan dwellings than US dwellings. The model developed, named the UPC-CETE model, predicts the airtightness of single-family dwellings as a function of the floor area, the age, the number of stories and the structure type: light or heavy. The airtihgtness values predicted with this model were smaller than those predicted with the model of the LBNL, as was expected. Finally, in order to validate and improve the model developed we carried out a series of trials to measure the air exchange rate in some Catalan dwellings. Measurements in sealed rooms were also performed with the aim of assessing the reduction gained on the air exchange rate with regards to the air exchange rate of the whole dwelling. On average, we obtained reductions of 35% and found that larger reductions belonged to old dwellings with small floor areas and 1 or 2 stories. The improved model was incorporated on the methodology to assess shelter in place effectiveness on the stage concerning the estimation of the air exchange rate of the dwellings located on the affected zone; therefore, the assumption of a constant value is avoided. These measurements and the model constitute therefore the first proposal for estimating the airtightness distribution of single-family dwellings that could be used by Catalan authorities for emergency response planning.

  • New trends for conducting hazard & operability (HAZOP) studies in continuous chemical processes  Open access

     Dunjó Denti, Jordi
    Defense's date: 2010-02-18
    Department of Chemical Engineering, Unversitat Politècnica de Catalunya
    Theses

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    Identifying hazards is fundamental for ensuring the safe design and operation of a system in process plants and other facilities. Several techniques are available to identify hazardous situations, all of which require their rigorous, thorough, and systematic application by a multi-disciplinary team of experts. Success rests upon first identifying and subsequently analyzing possible scenarios that can cause accidents with different degrees of severity. While hazard identification may be the most important stage for risk management, it depends on subjectivity issues (e.g., human observation, good judgment and intuition, creativity, expertise, knowledge) which introduce bias. Without a structured identification system, hazards can be overlooked, thus entailing incomplete risk-evaluations and potential loss. The present Thesis is focused on developing both managerial and technical aspects intended to standardize one of the most used techniques for hazard identification; viz. HAZard & Operability (HAZOP) study. These criteria have been carefully implemented not only to ensure that most of the hazardous scenarios will be identified, but also that US OSHA PSM Rule, EPA RMP, and Seveso Directive requirements will be accomplished. Chapter I pioneers the main research topic; from introducing the process safety concept up to the evidence of more detailed information is required from related regulations. A review of regulations (i.e., US, Europe legislation) focused on Hazard Identification has been conducted, highlighting, there is an absence of specific criteria for performing techniques intended to identify what can go wrong. Chapter II introduces the risk management system required to analyze the risk from chemical process facilities, and justifies that hazard identification stage is the Process Safety foundation. Hereafter, an overview of the key Process Hazard Analyzes (PHA) has been conducted, and the specific HAZOP weaknesses and strengths have been highlighted to establish the first steps to focus on. Chapter III establishes the scope, the purpose and the specific objectives that the research covers. It answers the following questions on the spot: why the present research is performed, which elements are included, and what has been considered for acquiring the final conclusions of the manuscript. Chapter IV gathers HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings with the purpose of classifying the research conducted over the years and finally define the HAZOP state-of-the-art. Additionally, and according to the information collected, the current HAZOP limitations have been emphasized, and thus, the research needs that should be considered for the HAZOP improvement and advance. Chapter V analyzes the data collected while preparing, organizing, executing and writing HAZOPs in five petroleum-refining processes. A statistical analysis has been performed to extract guidance and conclusions to support the established criteria to conduct effectively HAZOP studies. Chapter VI establishes the whole set of actions that have to be taken into account for ensuring a wellplanned and executed HAZOP study. Both technical and management issues are addressed, criteria supported after considering the previous chapters of the manuscript. Chapter VI itself is the result of the present research, and could be used as a guideline not only for team leaders, but also for any related party interested on performing HAZOPs in continuous chemical processes. Chapter VII states the final conclusions of the research. The interested parties should be released about the hazard identification related-gaps present in current process safety regulations; which are the key limitations of the HAZOP study, and finally, which are the criteria to cover the research needs that have been found Annex I proposes the key tools (tables, figures and checklists "ready-to use'') to be used for conducting HAZOPs in continuous chemical processes. The information layout is structured according to the proposed HAZOP Management System. This information is intended to provide concise and structured documentation to be used as a reference book when conducting HAZOPs. Annex II is intended to overview the most relevant petroleum refining processes by highlighting key factors to take into account in the point of view of process safety and hazard identification, i.e. HAZOP. In this sense, key health and safety information of specific petroleum refining units is provided as a valuable guidance during brainstorming sessions. Annex III illustrates the complete set of data collected during the field work of the present research, and also analyzed in Chapter V of the manuscript. Additionally, it depicts a statistical summary of the key variables treated during the analysis. Finally, the Nomenclature, References, and Abbreviations & Acronyms used and cited during the manuscript have been listed. Additionally, a Glossary of key terms related to the Process Safety field has been illustrated.

    La present Tesis doctoral té com a objectiu estandarditzar l'aplicació d'una de les tècniques més utilitzades a la industria de procés per a la identificació de perills; l'anomenat HAZard & OPerability (HAZOP) study, específicament a processos complexes, com per exemple, unitat de refineria del petroli.El capítol I defineix el concepte de Seguretat de Processos, i progressivament analitza les diferents regulacions relacionades amb la temàtica, detallant específicament les mancances i buits d'informació que actualment hi ha presents a la primera etapa de la gestió del risc en industries de procés: la identificació de perills.El capítol II defineix el sistema de gestió del risc tecnològic que aplica a les industries de procés, i es justifica que l'etapa d'identificació de perills és el pilar de tot el sistema. Finalment, es mencionen algunes de les tècniques d'identificació més utilitzades, els anomenats Process Hazard Analysis (PHA), i es detallen les seves mancances i fortaleses, característiques que han acabat definint la temàtica específica de la Tesis. Concretament, es dóna èmfasis a la tècnica anomenada HAZard & OPerability (HAZOP) study, objecte principal de la recerca.El capítol III defineix l'abast, el propòsit i els objectius específics de la recerca. La intenció d'aquest capítol és donar resposta a les següents qüestions: el perquè de la recerca, quins elements han estat inclosos i què s'ha considerat per tal d'assolir les conclusions de la Tesis.El capítol IV descriu l'estat de l'art de la literatura relacionada amb el HAZOP. Aquesta revisió no només permet classificar les diferents línies de recerca relacionades amb el HAZOP, sinó que també permet assolir un coneixement profund de les diferents particularitats de la pròpia tècnica. El capítol finalitza amb un conjunt de mancances tant de gestió com tècniques, així com les necessitats de recerca que poden millorar l'organització i execució dels HAZOPs.El capítol V analitza la informació que ha estat recopilada durant la fase experimental de la tesis. Les dades procedeixen de la participació en cinc estudis HAZOP aplicats a la industria de refineria del petroli.En aquest sentit, el capítol V desenvolupa una anàlisi estadística d'aquestes dades per extreure'n conclusions quant a la preparació, organització i execució dels HAZOPs.El capítol VI estableix el conjunt d'accions que s'ha de tenir en compte per tal d'assegurar que un estudi HAZOP estigui ben organitzat i executat (la metodologia). Es defineix un Sistema de Gestió del HAZOP, i a partir de les seves fases, es desenvolupa una metodologia que pretén donar suport a tots aquells punts febles que han estat identificats en els capítols anteriors. Aquesta metodologia té la intenció de donar suport i guia no només als líders del HAZOP, sinó també a qualsevol part interessada en aquesta temàtica.El capítol VII descriu les conclusions de la recerca. En primera instància s'enumeren les mancances quant a la definició de criteris a seguir de diferents regulacions que apliquen a la Seguretat de Processos.Seguidament, es mencionen les limitacions de la pròpia tècnica HAZOP, i finalment, es descriuen quins són els criteris establerts per donar solució a totes aquestes febleses que han estat identificades.L'Annex I és una recopilació de diferents criteris que han estat desenvolupats al llarg de l'escrit en forma de taules i figures. Aquestes han estat ordenades cronològicament d'acord amb les diferents fases que defineixen el Sistema de Gestió HAZOP. L'annex I es pot utilitzar com a una referència concisa i pràctica, preparada i pensada per ésser utilitzada directament a camp, amb la intenció de donar suport a les parts interessades en liderar estudis HAZOP.L'annex II recopila informació relacionada amb aspectes clau de seguretat i medi ambient en diferents unitats de refineria. Aquest informació és un suport per tal de motivar el "brainstorming" dels diferents membres que conformen l'equip HAZOP.L'Annex III recopila les dades de les diferents variables que han estat considerades a la fase experimental de la recerca, juntament amb un conjunt de figures que mostren la seva estadística bàsica.

  • Contribució a l'estudi de l'efecte del canvi d'escala en l'experimentació en incendis forestals  Open access

     Pérez Ramirez, Yolanda
    Defense's date: 2010-05-20
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Any rere any milions d'hectàrees són destruïdes pels incendis forestals, no només a Europa sinó arreu del món, tan sols cal recordar els dramàtics episodis viscuts a Califòrnia i Austràlia recentment. A banda de l'evident impacte mediambiental que això provoca -emissió de gasos d'efecte hivernacle, pèrdua de biodiversitat, acceleració de l'erosió del sòl, etc.- els incendis són també un problema social de primer ordre, que posa en perill a les persones i els seus béns. Davant d'aquesta situació, en les darreres dècades s'ha impulsat fortament la recerca en l'àmbit dels incendis forestals. Tanmateix, l'estudi dels incendis forestals és certament complex per les condicions i l'entorn on aquests es desenvolupen, a banda també del gran nombre de fenòmens -físics, químics i socials- que interaccionen al llarg de diferents escales espacials i temporals, per a donar lloc a l'inici i propagació del foc. És per això que bona part de la recerca sobre el comportament dels incendis forestals ha tingut lloc bàsicament al laboratori, tot i que qüestions com ara com traslladar aquests resultats experimentals als incendis reals, o bé fins a quin punt aquest tipus d'experimentació és útil o què és el que realment es pot extrapolar i què no, no han tingut encara cap resposta clara.L'objectiu d'aquesta tesi ha estat doncs el de contribuir a l'estudi del canvi d'escala en l'experimentació en incendis forestals pel què fa al comportament del foc, mitjançant les tècniques de l'anàlisi dimensional i de semblança. En primer lloc s'ha realitzat una extensa revisió bibliogràfica centrada bàsicament en aquells treballs que havien aplicat d'alguna manera o altra l'anàlisi dimensional i de semblança a l'estudi dels incendis i en particular dels incendis forestals. S'ha vist que no es possible realitzar un escalatge complet d'aquest fenomen i que el més utilitzat ha estat l'escalatge de Froude. A més s'ha detectat que mai abans s'ha aplicat aquest tipus d'anàlisi als models que s'utilitzen normalment avui dia en l'experimentació de laboratori. A continuació s'ha fet doncs una anàlisi exhaustiva de totes les variables que determinen el comportament d'un incendi forestal en els diferents escenaris experimentals (de laboratori i de camp). A partir d'aquestes variables s'ha realitzat una anàlisi dimensional per a estudiar la propagació d'un front de flames -tan bàsic com en condicions de vent i pendent- així com una anàlisi de semblança que ha permès obtenir les lleis d'escala per a les diferents variables que caracteritzen la propagació d'un incendi forestal. S'ha dissenyat i executat un programa experimental al laboratori amb l'objectiu de validar si es complien les lleis d'escala trobades i de determinar-ne el rang de validesa i les possibles causes en cas que no es complissin.Els resultats obtinguts han mostrat que per a fronts de flama bàsics propagant-se sense vent ni pendent, totes les variables analitzades segueixen les lleis d'escala derivades de l'estudi teòric, en el rang de longituds de front de flama abraçat que va dels 25 cm als 3 m. Nogensmenys cal remarcar que paràmetres com la humitat i el tipus de combustible o les característiques de la instal·lació experimental utilitzada poden alterar enormement els resultats si no es controlen adequadament. En el cas dels fronts de flama propagant pendent amunt, els resultats han mostrat que les lleis d'escala de la geometria de flama es compleixen per a tot el rang de pendents estudiat que va de 0 fins a 30°, mentre que en el cas de la llei d'escala de la velocitat de propagació deixa de complir-se per a pendents de 30°. Finalment, en el cas dels fronts de flama propagant en condicions de vent, els resultats han mostrat que per a velocitats del vent superiors a aproximadament 2,5 m/s les lleis d'escala tant de la velocitat de propagació com de la geometria de flama deixen de complir-se.Al final d'aquest treball s'apunten les causes que poden conduir a l'incompliment de les lleis d'escala així com als factors que poden restar validesa als experiments efectuats a escala de laboratori, quan es vol extrapolar els resultats a escales més grans o fins i tot a incendis reals.

    Year after year millions of hectares are destroyed by wildland fires, not only in Europe but all over the world; just remember the dramatic episodes recently occurred in California or Australia. Besides the evident environmental impact caused by these fires -emission of greenhouse gases, biodiversity loss, soil erosion, etc- wildland fires represent also a social problem of primary order that threatens human life and their assets.Because of this situation, during the last decades research on wildland fires has been greatly boosted. Nevertheless, the study of forest fires is really complex due to the conditions and the environment in which they develop and to the number of phenomena -physical, chemical and social- that interact all along the different spatial and temporal scales that give rise to the start and development of a fire. That is partly the reason because the study of wildland fire behaviour has mainly been developed in laboratories, but questions like how these experimental results can be translated to real fires?, or is really this kind of experimentation useful?, or what can be extrapolated? These questions have not yet received a clear answer.The goal of this work was to improve the knowledge on the effect of changing the scale in the experimental study of forest fire behaviour, by means of dimensional and similarity analysis. First an extended bibliographic review has been done, centred on those works that had applied in one or another way the dimensional and similarity analysis to the study of fires and more specifically to forest fires. It was observed that it is not possible to undergo a complete scaling of a forest fire and that the most used partial scaling technique was the Froude scaling. Moreover it was detected that this kind of analysis was never before applied to the laboratory models used currently to obtain experimental data on wildland fires. Thus, an exhaustive analysis of all the variables affecting forest fire behaviour has been carried out for the diverse experimental scenario (in the lab and field). From these variables, a complete dimensional analysis has been developed in order to study the spread of a flames front -both in basic conditions and with slop or wind- and a subsequent similarity analysis has provided the scaling laws governing all the variables under study. A complete experimental program has been designed and developed in the laboratory with the aim of validating the scaling laws previously found and to establish the possible causes of any failure of the laws. The results obtained show that in the case of a basic flame front, spreading under no wind and no slope conditions, all the variables analysed followed the scaling laws obtained during the theoretical study for flames front lengths ranging from 25 cm to 3 m. For the tests under slop conditions, the results indicate that the scaling laws corresponding to the flame geometry are verified for all the slopes tested which range from 0 to 30°, while in the case of the rate of spread scaling law is no longer verified for the 30° slope. Finally, in the case of flame fronts spreading under wind conditions, the results show that for wind speed values greater than 2,5 m/s neither of the scaling laws corresponding to the flame geometry and the rate of spread, are verified. It has also been observed that parameters such as moisture content, the type of fuel or the specific design of the experimental device used can have a big influence on the results obtained if they are not adequately controlled.At the end of this work, the main causes leading to the failure of the scaling laws are pointed out together with the factors that can make the laboratory experiments less reliable when trying to extrapolate the results to larger scales or even to real fires.

  • ANÁLISIS INTEGRADO DE LA CALIDAD DEL AIRE EN LA COSTA NORORIENTAL DE VENEZUELA

     Rincón Polo, Gladys
    Defense's date: 2010-12-01
    Department of Engineering Design, Universitat Politècnica de Catalunya
    Theses

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  • La investigació d'incendis i explosions

     Planas Cuchi, Eulalia; Bosch Tous, Ricardo; Marimón Viadiu, Frederic; Josep, Boixadé; Casafont Ribera, Miquel; Gavarró, Pau; Gràcia, Joan; Hernández, Florenci; Nadal, Rafael; Pedreny, Joan; Rejat, Miquel; Romero, Esperança; Sans, Jordi
    Date of publication: 2010-10-01
    Book

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  • Disseny dels experiments i metodologia. Descripció dels procediments i equips utilitzats en la monitorització dels focs experimentals ex-situ.

     Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Domenech Jardi, Ruth; AGUEDA COSTAFREDA, ALBA
    Date: 2010-11-25
    Report

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  • Propietats extrínseques del combustible de les parcel les estudiades

     Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Domenech Jardi, Ruth; AGUEDA COSTAFREDA, ALBA
    Date: 2010-01-18
    Report

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    L’objectiu del present document és obtenir una bona caracterització de les propietats extrínseques del combustible present a les parcel·les d’estudi, les propietats intrínseques quedaran recollides en el DR3 (Propietats intrínseques del combustible de les parcel·les estudiades). El contingut d’aquest document s’estructura de la següent forma: en primer lloc, es llisten les propietats extrínseques que són necessàries per dur a terme les simulacions; una vegada conegudes aquestes propietats, en el següent apartat es descriu el disseny experimental dels mostrejos; a continuació es detalla la metodologia utilitzada per determinar les propietats extrínseques a camp.; i els darrers tres apartats del document fan referència als resultats obtinguts, a l’anàlisi i conclusions extretes d’aquests.

  • Propietats intrínseques de restes d¿aclarida en regenerats de pi blanc. Mètodes i resultats experimentals.

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa; Domenech Jardi, Ruth; AGUEDA COSTAFREDA, ALBA
    Date: 2010-03-24
    Report

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    L’objectiu d’aquest document és recopilar els resultats del treball realitzat en el Bloc 3 “Propietats intrínseques” del projecte IRVA. Aquests resultats han de servir juntament amb d’altres paràmetres característics de les zones d’estudi (propietats extrínseques, característiques topogràfiques i condicions meteorològiques) com a dades d’entrada per tal de realitzar les simulacions amb les diverses eines seleccionades, tasca que es desenvolupa en el Bloc 5 “Avaluació dels models de comportament d’incendis”. L’estructura d’aquest document és la següent: en primer lloc es recopilen els resultats obtinguts en la caracterització de les propietats tèrmiques, seguidament s’inclouen els resultats referents a densitat i geometria de partícules i en darrer lloc es recopilen, a nivell de consideracions finals, les conclusions més importants extretes d’aquest bloc de treball.

  • Characterization of Laboratory-Scale Fires Propagating Under the Effect of a Long-Term Retardant

     AGUEDA COSTAFREDA, ALBA; Pastor Ferrer, Elsa; Pérez, Yolanda; Viegas, Domingo Xavier; Planas Cuchi, Eulalia
    Combustion science and technology
    Date of publication: 2010
    Journal article

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    Laboratory experiments were conducted in straw fuel beds in order to characterize the effect of a widely used long-term retardant on fire behavior under different conditions: no slope–no wind, upslope–no wind, and no slope–upwind. The results are reported in terms of reduction factors for a set of variables characterizing fire behavior. In the experimental conditions the values of upslope–no-wind and no-slope–upwind fires showed no statistically significant differences from those of no-slope–no-wind fires. For all types of fire, values obtained for the reduction factors on rate of spread, fuel consumption ratio, fire intensity, and flame length were 63%, 36%, 77%, and 54%, respectively.

  • A comparative analysis of mathematical models for relating indoor and outdoor toxic gas concentrations in accidental releases

     Montoya, MI; Planas Cuchi, Eulalia; Casal Fabrega, Joaquim
    Journal of loss prevention in the process industries
    Date of publication: 2009-04
    Journal article

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    This paper surveys various models for estimating indoor concentration as a function of outdoor concentration in the event of an accidental release or chemical attack involving toxic substances. It is essential to know indoor concentration in order to estimate the effectiveness of shelter in place as a protective measure. Several models—deposition, one-sink, sink-diffusion and two-sink—were considered. These models can be derived from a general model by making different assumptions. The models showed significant variations in terms of the adsorption/desorption considerations. Since indoor materials act as reservoirs, adsorption may lead to a significant decrease in indoor concentration, but subsequent desorption may also take place. The models require the knowledge of a set of parameters that are specific to each compound and material, which are currently scarce in the literature. As a result, the more complex and complete the model, the more limited its applicability. Outdoor concentrations obtained from a Gaussian model and originating from three source types (continuous, temporary and instantaneous) were used as inputs in the reviewed models. Indoor concentrations of chlorine and sarin from a temporary source were estimated in order to compare the predictions of the models.

  • Estudio experimental y modelización matemática de dardos de fuego  Open access

     Gómez Mares, Mercedes
    Defense's date: 2009-11-27
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Investigation of real cases as a way to teach risk analysis

     Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Vilchez Sanchez, Juan Antonio; Planas Cuchi, Eulalia
    World Congress of Chemical Engineering
    Presentation of work at congresses

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  • Experimental study of the emissivity of flames resulting from the combustion of forest fuels

     Costafreda, Alba; Pastor Ferrer, Elsa; Pérez, Yolanda; Planas Cuchi, Eulalia
    International journal of thermal sciences
    Date of publication: 2009-06
    Journal article

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    Heat transfer by radiation is taken into account in most models that predict the propagation of forest fires. This heat transfer mechanism is normally formulated according to the Stefan–Boltzmann law in terms of flame temperature and flame emissivity. This study focused on flame emissivity. Experimental studies carried out to compute the emissivity of the flames generated during the combustion of forest fuels were reviewed, thereby highlighting differences in methodologies and results. Since the results of these studies with regard to the exponential relationship between flame emissivity and flame thickness were not in agreement, two methods based on IR imagery were used in the present study to calculate flame emissivity values. Nine circular fuel beds with a diameter of 0.3–2.5 m were prepared with common Mediterranean species and burned as stationary fires. An exponential correlation between flame emissivity and flame thickness was observed for both methods. According to the results of this study, only flames thicker than 3.2 m would exhibit an emissivity close to that of a blackbody (0.9), and the associated extinction coefficient would be 0.72. A long-term retardant product was used to treat the fuel of two of the nine tests that were carried out and no effect on flame emissivity was observed.

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    Air leakage in Catalan dwellings: Developing an airtightness model and leakage airflow predictions  Open access

     Montoya, Maria I.; Pastor Ferrer, Elsa; Carrié, F. Rémi; Guyot, Gaelle; Planas Cuchi, Eulalia
    Building and environment
    Date of publication: 2009-12
    Journal article

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    In this study we estimate the air leakage distribution of single-family dwellings in Catalonia and use a statistical analysis of an airtightness database for single-family dwellings in France to identify the building characteristics that have the greatest influence on airtightness. The most significant variables are found to be the structure type, the floor area, the age of the building, the number of stories and the insulation type. A multiple linear regression technique is then applied to establish a predictive model for deriving an estimated value of airtightness from these characteristics. To estimate the infiltration airflow, a stochastic simulation of the building characteristics was performed per census tract using real data on the distributions of building variables taken from the census information. The model is then applied to determine the power law coefficient and the airtightness distribution. The predicted flow coefficients are combined with the AIM-2 model and given meteorological conditions to determine the infiltration airflow. Two sets of meteorological conditions are considered: average conditions and extreme conditions for each season.

  • Effects of long-term forest fire retardants on fire intensity, heat of combustion of the fuel and flame emissivity  Open access

     AGUEDA COSTAFREDA, ALBA
    Defense's date: 2009-10-30
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Cada any milers d'hectàrees forestals es destrueixen a causa dels incendis forestals. Investigar quins són els mecanismes que controlen la ignició i la propagació dels incendis forestals és necessari per planificar estratègies eficients de lluita contra els incendis forestals i per establir plans de gestió de les àrees forestals. Durant aquests darrers seixanta anys des del món de la recerca s'han formulat models per descriure el comportament dels focs forestals de superfície, principalment, i en un menor grau els focs de capçades. No obstant, aquests models tenen un punt feble significatiu: cap d'ells ha estat desenvolupat per ser utilitzat com a eina predictiva del comportament del foc després d'actuacions d'atac indirecte amb retardants a llarg termini (o retardants). A més, la majoria de treballs desenvolupats fins ara amb retardants a llarg termini han tingut l'objectiu d'avaluar diferents productes per al seu ús públic per comparació amb un de referència.L'objectiu del present estudi ha estat millorar el coneixement sobre l'efecte dels retardants a llarg termini en el comportament dels incendis forestals. L'efecte dels retardants sobre la intensitat del front de flames ha estat quantificat per a diferents condicions (sense pendent/sense vent, sota la influència del vent, sota la influència del pendent), així com l'efecte dels retardants sobre la calor de combustió del combustible forestal i l'emissivitat de la flama. Avaluar com varien aquests dos últims paràmetres per la presència de retardant al combustible és un primer pas per incloure en els models de propagació l'efecte de les operacions d'atac indirecte amb retardants.Per a les condicions experimentals provades en aquest estudi, hem trobat que la intensitat del front de flames es redueix en un factor de 0.8 per la presència de retardant. També s'ha observat que la quantitat de calor alliberada durant la combustió amb flama es redueix en un factor de 0.18 per la presència de retardants i que l'emissivitat de la flama no es veu afectada per la presència de retardants. Aquests resultats indiquen que la presència de retardant redueix la intensitat del front de flames fonamentalment perquè es redueix la quantitat de calor efectivament alliberada per unitat de massa de combustible, més que perquè les propietats radiatives de la flama es canviïn.

    Every year, thousands of hectares of forest are destroyed by wildland fires. It is necessary to investigate the mechanisms that influence the ignition and propagation of wildland fires in order to successfully devise strategies for fighting wildland fires and to establish plans for managing forest areas or grasslands. Researchers have been formulating models to describe surface fires and, to a lesser extent, crown fires, for more than sixty years. However, these models have a significant shortcoming: none of them has been developed for use as a tool to predict fire behavior after indirect attack operations with long-term retardants. Furthermore, most of the work done to date on long-term retardants has been with the goal of evaluating these products for commercial purposes.The goal of the present study was to improve knowledge of the effects of long-term retardants on the spread of forest fires. Retardants' effects on fire intensity were quantified for varying fire situations (no-slope/no-wind, upslope, upwind), together with retardants' effects on the heat of combustion of the fuel and flame emissivity. Assessing how these last two parameters change due to the presence of retardants on the fuel is a first step towards including the effects of indirect attack operations with long-term retardants in propagation models. We found that the presence of retardants reduced fire intensity by a factor of 0.8 under the experimental conditions tested in this study. The amount of heat effectively released during flaming combustion under the presence of retardants was observed to decrease by a factor of 0.18 in comparison with untreated samples and flame emissivity was observed to be unaffected by the presence of retardants. These results indicated that the presence of retardants reduces fire intensity primarily by reducing the amount of heat effectively released per unit mass of fuel, rather than by affecting the radiation properties of the flames.

  • Computing aerial suppression effectiveness by IR monitoring

     Pérez Ramirez, Yolanda; Gould, J; Pastor Ferrer, Elsa; Planas Cuchi, Eulalia; Plucinski, M
    Mediterranean Combustion Symposium
    Presentation of work at congresses

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    This paper describes the methodology developed to analyse the 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 be able to extract the maximum information from the IR images taken from an observing helicopter, in those tests were 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.

  • Teaching risk analysis through the investigation of real cases

     Casal Fabrega, Joaquim; Darbra Roman, Rosa Maria; Vilchez Sanchez, Juan Antonio; Planas Cuchi, Eulalia
    World Congress of Chemical Engineering
    Presentation's date: 2009-08-25
    Presentation of work at congresses

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  • ESTUDIO DE LA GEOMETRIA DE LLAMA Y DEL EFECTO DEL CAMBIO DE ESCALA PARA LA MODELIZAICÓN DEL COMPORTAMIENTO DE LOS INCENDIOS FORESTAL

     AGUEDA COSTAFREDA, ALBA; Pérez Ramirez, Yolanda; Pastor Ferrer, Elsa; Planas Cuchi, Eulalia
    Participation in a competitive project

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  • NT2-1. Llistat de propietats extrínseques i relació de mètodes a utilitzar.

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa; Domènech, R
    Date: 2009-03
    Report

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  • NT 5.1. Breu descripció dels models i llistat de variables

     Planas Cuchi, Eulalia; Pastor Ferrer, Elsa; Domènech, R
    Date: 2009-03
    Report

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