Freshwater access has always been and is continuing to be a severe problem in desert coastal regions, despite the fact that they have an unlimited supply of easily accessible saline water. Water desalination plants are well established and heavily relied upon throughout the Middle East, Saudi Arabia in particular. However, water desalination tends to be a very expensive and energy intensive solution to the problem. The transition from using open water intake systems and all of the pretreatment processes that they require, to using seabed water filters as an intake, would potentially reduce the lifetime costs, energy consumption, and environmental impacts commonly associated with water desalination. This is because the filtration process that the seabed filter generates, serves as sufficient pretreatment for seawater as well as eliminating any risk of entrainment or impingement of marine organisms. The main objective of this research is to conduct a feasibility study on Om Almisk Island, an island off the coast of King Abdullah University of Science and Technology (KAUST), to determine if it would be a suitable location to construct a seabed water filter as a replacement for the current open water intake. The Om Almisk Island site was evaluated through collection of sand samples over a radial grid around Om Almisk Island and sample analysis using grain size distribution, porosity, and hydraulic conductivity. The lack of mud, high hydraulic conductivity, proximity to KAUST, and the shallow waters of the sandy apron surrounding Om Almisk Island make this an ideal location for a seabed water filter to be used as an intake and pretreatment for the KAUST desalination plant. This location also has low tide change and the presence of benthic macrofauna to create bioturbation in the sediments, which could inhibit the growth of a schmutzdecke. If this biological layer forms, it could drastically reduce the hydraulic conductivity of the system. Due to the high hydraulic conductivity of the native sand, a relatively small footprint is possible for the design of the filter. A design with an intake of 105,000 m3/day, using four active galleries and one standby gallery was generated.

The goal of this study was to evaluate the feasibility of using advanced coagulation with Fe(VI) in coagulation-flocculation-sedimentation/ flotation systems for the pretreatment of SWRO desalination plants during algal bloom events. Algal organic matter (AOM) material extracted from marine diatom species (Chaetoceros affinis) was added to Red Sea water to mimic algal bloom conditions. Low dosage of Fe(VI) (<1 mg Fe/L) was very effective at improving feed water quality containing AOM (algal bloom conditions). Based on results from both a bench-scale DAF unit and Jar testing unit, 0.75 mg Fe/L of Fe (VI) proved to be effective at improving the raw water quality which is comparable to the performance of 1 and 3 mg Fe/L of Fe (III). The removal efficiency for both testing units with the use of Fe(VI) was up to 100% for algae , 99.99% for ATP, 99% for biopolymers and 70 % for DOC. The improvement in Fe(VI) performance is related to the simultaneous action of Fe(VI) as oxidant, disinfectant and coagulant. The performance of Fe(VI) coagulant was also evaluated with the use of coagulant aids (clays). The overall turbidity, DOC, biopolymers and algal cells removal was improved via using Fe(VI) and clays at very low dose. Generally, it was found that for the same pretreatment performance achieved, a much lower Fe(VI) dose was required compared to Fe (III), which make it important to study of cost effectiveness for using Fe(VI) instead of Fe(III) and estimate cost savings during algal bloom conditions. A detailed cost comparative study was conducted for Fe(III) vs. Fe(VI) coagulation process based on the removal efficiency. The use of Fe(VI) reduced the total pretreatment cost by 77% and sludge disposal cost by > 88% compared to the use of Fe(III) in the pretreatment process. The use of Fe(VI) reduces the operational and maintenance cost in SWRO desalination plant by 7% and the production cost by 4%. This study proved that the use of Fe(VI) during high turgidity and algal bloom conditions helped providing high raw water quality to the RO process with lower chemicals and operations cost as well as low chlorine and iron residuals.

Radio Occultation (RO) is a remote sensing technique which uses Global Navigation Satellite System (GNSS) signals tracked by a Low-Earth Orbit (LEO) satellite to sound the earth's atmosphere both in low (troposphere, stratosphere) and high (ionosphere) altitudes. GNSS-RO provides global coverage and SI traceable measurements of atmospheric data with high-vertical resolution. Refractivity, dry temperature, pressure and water vapour profiles retrieved from RO measurements have a relevant contribution in Numerical Weather Prediction (NWP) systems and in climate-monitoring. Due to the partial propagation through the ionosphere, a systematic bias is added to the lower atmospheric data product. Most of this contribution is removed by a linear combination of data for two frequencies. In climatology studies, one can apply a second-order correction - so called κ-correction - which relies on a priori information on the conditions in the ionosphere. However, both approaches do not remove high-order terms in the error due to horizontal gradient and earth's geomagnetic fields. The remaining residual ionospheric error (RIE) and its systematic bias in RO atmospheric data is a well-known issue and its mitigation is an open research topic. In this licentiate dissertation, the residual ionospheric error after the standard correction is evaluated with computational simulations using a wave optics propagator (WOP). Multiple Phase Screen (MPS) method is used to simulate occultation events in different ionospheric scenarios, e.g. quiet and disturbed conditions. Electron density profiles (EDP) assumed in simulations are either defined by analytical equations or measurements. The disturbed cases are modelled as small-scale irregularities within F-region in two different ways: as sinusoidal fluctuations; and by using a more complex approach, where the irregularities follow a single-slope power-law that yields moderate to strong scintillation in the signal amplitude. Possible errors in MPS simulations assuming long segment of orbit and ionosphere are also evaluated. The results obtained with the sinusoidal disturbances show minor influence in the RIE after the standard correction, with the major part of the error due to the F-region peak. The implementation of the single-slope power-law is validated and the fluctuations obtained in simulation show good agreement to the ones observed in RO measurements. Finally, an alternative to overcome limitations in MPS simulations considering occultations with long segment of orbit and ionosphere is introduced and validated. The small-scale irregularities modelled in F-region with the power-law can be added in simulations of a large dataset subjected to κ-correction, in order to evaluate the RIE bending angle and the consequences in atmospheric parameters, e.g. temperature. / NRPF-3, Rymdstyrelsen, 241/15

Yes / The coupling of thermal (Multi Stage Flash, MSF) and membrane processes (Reverse Osmosis, RO) in desalination systems has been widely presented in the literature to achieve an improvement of performance compared to an individual process. However, very little study has been made to the combined Multi Effect Distillation (MED) and Reverse Osmosis (RO) processes. Therefore, this research investigates several design options of MED with thermal vapor compression (MED_TVC) coupled with RO system. To achieve this aim, detailed mathematical models for the two processes are developed, which are independently validated against the literature. Then, the integrated model is used to investigate the performance of several configurations of the MED_TVC and RO processes in the hybrid system. The performance indicators include the fresh water productivity, energy consumption, fresh water purity, and recovery ratio. Basically, the sensitivity analysis for each configuration is conducted with respect to seawater conditions and steam supply variation. Most importantly, placing the RO membrane process upstream in the hybrid system generates the overall best configuration in terms of the quantity and quality of fresh water produced. This is attributed to acquiring the best recovery ratio and lower energy consumption over a wide range of seawater salinity.

Yes / Reverse Osmosis (RO) process can be considered as one of the intensively used pioneering equipment for reusing wastewater of several applications. The recent study presented the development of an accurate model for predicting the dimethylphenol removal from wastewater via RO process. The Response Surface Methodology (RSM) was applied to carry out this challenge based on actual experimental data collected from the literature. The independent variables considered are the inlet pressure (5.83-13.58) atm, inlet temperature (29.5-32) ° C, inlet feed flow rate (2.166-2.583) × 10-4 m3/s, and inlet concentration (0.854-8.049) × 10-3 kmol/m3 and the dimethylphenol removal is considered as the response variable. The analysis of variance showed that the inlet temperature and feed flow rate have a negative influence on dimethylphenol removal from wastewater while the inlet pressure and concentration show a positive influence. In this regard, F-value of 240.38 indicates a considerable contribution of the predicted variables of pressure and concentration against the process dimethylphenol rejection. Also, the predicted R2 value of 0.9772 shows the high accuracy of the model. An overall assessment of simulating the performance of RO process against the operating parameters has been systematically demonstrated using the proposed RSM model.

Yes / The total energy consumption of many Reverse Osmosis (RO) plants has continuously improved as a result of manufacturing highly impermeable membranes in addition to implementing energy recovery devices. The total energy consumption of the RO process contributes significantly to the total cost of water treatment. Therefore any way of keeping the energy consumption to a minimum is highly desirable but continues to be a real challenge in practice. Potential areas to explore for achieving this include the possibility of optimising the module design parameters and/or the associated operating parameters. This research focuses on this precise aim by evaluating the impact of the design characteristics of membrane length, width, and feed channel height on the total energy consumption for two selected pilot-plant RO process configurations for the removal of chlorophenol from wastewater. The proposed two configurations, with and without an energy recovery device (ERD), consist of four cylindrical pressure vessels connected in series and stuffed with spiral wound membranes. A detailed steady-state model developed earlier by the authors is used here to study such impact via repetitive simulation. The results achieved confirm that the overall energy consumption can be reduced by actually increasing the membrane width with a simultaneous reduction of membrane length at constant membrane area and module volume. Energy savings of more than 60% and 54% have been achieved for the two configurations with and without ERD respectively using process optimization. The energy savings are significantly higher compared to other available similar studies from the literature.

A dirofilariose canina é uma parasitose de distribuição mundial cujo agente etiológico é um verme nemátoda filarióide. Em sua fase adulta, os vermes produzem microfilárias por meio de reprodução sexuada. Sua transmissão ocorre por meio de mosquitos que atuam como hospedeiros intermediários. No Brasil, até o momento, a dirofilariose canina foi encontrada em 15 estados de todas as regiões. A maioria dos estudos está concentrada nas regiões sudeste e sul. A prevalência nacional é de 2%, embora alguns trabalhos tenham encontrado prevalências locais mais elevadas. Neste trabalho apresentamos o primeiro registro de dirofilariose canina para o estado de Rondônia com mapas de distribuição dos cães positivos e análise de mosquitos. Amostras de sangue de 727 cães foram coletadas aleatoriamente na cidade de Porto Velho. As amostras forma analisadas em busca de microfilárias e antígenos circulantes usando duas técnicas: microscopia ótica de gota espessa corada com Giemsa e imunocromatografia de fluxo lateral (ICT). As amostras positivas foram também testadas por PCR, as negativas forma testadas na mesma técnica em pools. Mosquitos foram coletados no domicilio e peridomicílio de todos os casos de cães positivos, estes mosquitos foram testado por PCR em busca de DNA de Dirofilaria immitis. Um mapa de distribuição dos casos de cães positivos foi elaborado. Noventa e três amostras de sangue foram positivas no ICT, representando 12,8% da amostra total, nenhuma amostra foi positiva na gota espessa. O PCR das amostras de sangue resultou em 10% para as positivas no ICT e 0% nas negativas no mesmo teste. Entre os 93 cães positivos, 89 (95,7%) nasceram em Porto Velho. Nenhuma diferença estatística foi observada entre cães que moram em quintais ou intradomicílio. O mapa de distribuição indica um hotspot na região norte da cidade. O PCR dos mosquitos resultou em apenas um pool positivo. A transmissão de dirofilariose canina ocorre na cidade de Porto velho e a frequência que ocorre nos cães é considerada moderada. A técnica de imunocromatografia e PCR são mais eficazes na detecção de dirofilariose comparadas a gota espessa. A confirmação de transmissão de dirofilariose canina em Porto Velho, coloca esta doença no ranking de diagnóstico diferencial de nódulos pulmonares em Porto Velho. / Heartworm is an infectious disease with worldwide distribution. Mosquitoes acts as intermediary host and vectors. In Brazil, until now, heatworm was found in 15 states with an national average of 2%. This present work aims to report for the first time canine heartworm in the state of Rondônia and confirms the transmission of the disease in the state. Blood samples were randomly collected from 727 dogs in the municipality of Porto Velho. The samples were analyzed for the presence of microfilariae and circulating antigens using two different techniques: thick blood microscopy stained with Giemsa and immunochormatography for the detection of filarial antigens. Aiming to test the efficacy of the immunoassay test, all the positive cases were examined by PCR and pools of negative samples were also examined. Mosquitoes were collected at the domiciles presenting positive cases and analyzed by PCR. A distribution map was made with positive cases. Ninety three blood samples out of 727 (12.8%) were positive by the immunoassay technique and none by the thick smear method. All the positive cases by the immunoassay technique were examined by PCR and pools of all negatives samples were also examined resulting in 10% and 0% positivity frequency, respectively. Among the 93 positive dogs, 89 (95.7%) were born in Porto Velho. No differences in the frequency of infection were observed between dogs raised indoor or in the yards. The distribution map indicates a hotspot in the north area of the city. Mosquitoes were analyzed by PCR, resulting in only one positive pool. This result shows that the transmission of canine heartworm is occurring in the municipality of Porto Velho and has moderate prevalence among dogs. The immunoassay technique and the PCR method are more efficient in detecting D. immitis infections in dogs when compared to the blood smear technique. The confirmation of heartworm transmission in Porto Velho also includes this disease among the ranks of differential diagnosis of pulmonary nodules in humans in Rondônia.

Cette thèse a pour objet l’étude de la IIe province de Basse-Égypte, et de ses villes, dont la principale était Khem/Sékhem. Cette région devint le nome Létopolite à partir de l’époque ptolémaïque d’après sa métropole nouvellement nommée Létopolis. De nos jours, elle correspond, approximativement, au nord du gouvernorat de Giza et seuls quelques vestiges y furent retrouvés, notamment à l’emplacement de l’ancienne métropole, aujourd’hui Aousîm, située à 12 km au nord-ouest du Caire. Ces découvertes ne permettent pas d’appréhender à leur juste valeur la toponymie et les cultes anciens. En revanche, la province et les quelques toponymes qui peuvent y être localisés - Khem/Sekhem, Iyt, Imhedj/Kemhedj, Sakhebou, Ro-hésaou, Sa-ta, … - sont présents dans des sources égyptiennes, à la fois sacrées et profanes, provenant de l’extérieur de cette région et cela depuis l’Ancien Empire jusqu’à l’époque romaine. Le corpus documentaire établi réuni ainsi les documents mentionnant les toponymes de cette zone d’étude, ses dieux ou les titres locaux, depuis la période thinite jusqu’à l’époque romaine, en langue égyptienne et en écriture hiéroglyphique, hiératique et démotique. La finalité de ce travail ayant pour but de dresser un portrait général de cette région, principalement par le biais d’une étude de géographie religieuse, et d’essayer, à partir de sources qui lui sont extérieures, de déterminer quels pouvaient être les contextes locaux, et ceux dépendant d’une théologique nationale et extérieure à sa région. Quatre axes principaux sont développés dans la synthèse. Premièrement, l’étude des lieux vise à présenter leur toponymie, leur éventuelle identification et localisation, leur fonction ainsi que les éléments historiques connus. La deuxième partie aborde les dieux en-eux-mêmes, classés selon leur ville, ou sanctuaire principal, en détaillant leurs fonctions et leurs caractéristiques. Troisièmement, nous abordons les mythes, les rites et les res sacrae de la province qui présentent ainsi les thèmes principaux qui lui sont rattachés localement et dans la religion nationale. Enfin, la quatrième partie est consacrée à une étude prosopographique et une analyse des titres apparaissant dans la province en présentant les différentes familles enregistrées et les titres et fonctions qu’elles portaient durant toute l’Histoire égyptienne. / The aim of this PhD is to study the 2nd province of Lower Egypt, and its towns, of which the main one was Khem/Sekhem. This area was called the Letopolite nome since the Ptolemaic Period and according to its new metropolis : Letopolis. Nowadays, this province is situated to the north of Giza’s governorate where some remains were found, particularly on the site of the former metropolis, todays Ausim which is located 12 km northwest of Cairo. These findings don’t provide a lot of information about places and cults in this region. However, the province and some identified place names in the region (Khem/SekhemIyt, Imhedj/Kemhedj, Sakhebu, Ro-hesau, Sa-ta ...) are present in other Egyptian sources, sacred and profane. The established corpus of gathered documents mentioning a place-name of the region, its gods or local titles from the Early Dynastic Period up to the Greco-Roman Period in Egyptian, hieroglyphic, hieratic and demotic language. The purpose of this study aiming at drawing up a general view of the sacred geography of this region and, at trying from sources which are outside it, to determine what could be the local contexts, and those dependent of a national theology. Four main themes are developed in the essay. Firstly, the study of the places introduces their names, their possible location and identification, function and historical elements known when possible. The second part broaches the gods-themselves, classified according to their main city or sanctuary while detailing their duties. Thirdly, we discuss the myths, rites and res sacrae of the province and present the main topics that are attached to this province locally and in the national religion. The fourth part is devoted to a prosopographic study and analysis of the titles appearing in the province by presenting the various registered families, the titles and the functions they bore throughout Egyptian history.

A Indústria Naval tem investido em navios cada vez maiores visando ganhos de escala. Na última década, esse movimento se intensificou e um dos principais fatores é a influência significativa das economias emergentes na demanda de carga. Alguns dos ganhos decorrentes da utilização de navios maiores são: menor consumo de energia, menor emissão de CO2, maior capacidade de carga e, consequentemente, fretes marítimos mais competitivos. Esses novos navios acarretam a necessidade de uma revisão da infraestrutura portuária, isso porque geram uma alta concentração de carga e ainda demandam uma maior profundidade nos portos, bem como alterações nas estruturas dos terminais para recebê-los. Investimentos como dragagem, modificações de layout de terminais, entre outros, resultam em custos demasiadamente altos, além de impactos relacionados a licenciamentos para operação. Neste cenário de aumento dos navios e da consequente dificuldade de recebê-los em diversos portos, uma solução que vem sendo utilizada ao redor do mundo é a do transbordo de navio para navio no mar, o transshipment. Ele é normalmente realizado através de um navio convertido em plataforma de transbordo/transferência, substituindo a necessidade de ancoragem do navio de maior capacidade em um terminal portuário convencional. O Brasil tem o desafio de se preparar para este novo cenário e o porto de Santos, o principal do país, possui limitações para recebimentos destas embarcações. Este trabalho analisou operacionalmente e sob o ponto de vista de custos logísticos, o processo de transshipment no mar em portos brasileiros. Para tal, escolheu como estudo de aplicação o minério de ferro no porto de Santos, usando como ferramentas de análise a simulação e a comparação de custos logísticos totais das alternativas. Os resultados obtidos nas análises demonstraram a capacidade do transshipment de atender à demanda de carga em diferentes cenários e trazer uma redução de custos logísticos em relação à operação convencional. / The Shipbuilding Industry has invested in larger vessels for economies of scale. In the last decade, this movement has intensified and one of the main factors is that emerging economies have significantly influenced demand for cargo. Some of the gains from the use of larger ships are: lower energy consumption, lower CO2 emissions, higher cargo capacity and more competitive sea freight as a consequence. These new ships require a revision of the port infrastructure due to their higher concentration of cargo and still require a greater depth in the ports, as well as changes in the structures of the terminals to receive them. Investments such as dredging, modifications of terminal layout among others result in high costs, in addition to the need for upgrading licenses to operate. A solution that is being used around the world is the transshipment. It is usually accomplished through a ship converted as a transfer platform, replacing the need for anchoring the larger vessel at a conventional port terminal. Brazil needs to be prepared for this challenge and the port of Santos, the main port of the country, has limitations for receiving these vessels. This work assessed operationally and from the point of view of logistics costs, the transshipment in Brazilian ports. To do so, it carried out an application study to the iron ore in the port of Santos, using simulation and the comparison of total logistical costs of the alternatives. The results obtained demonstrated the capacity of the transshipment to attend the demand for cargo in different scenarios and reduce cost in relation to the conventional operation.

A ship to which vehicles and other loads can be rolled on and off is usually named ro-ro ship. A ro-ro ship consists of large corridor shaped space, normally extending to a considerable length or the entire length of the ship, which is usually loaded with various vehicles or stowage units. A ro-ro space can either be designed as an open space, closed space or a weather deck. There have been several fire incidents in ro-ro ship spaces and these fires occur with a relatively high frequency. A fire on a ro-ro ship is a very complex phenomenon. The fire development is hard to predict, and the fire tend to grow very quickly. One crucial parameter for the development of these fires is the ventilation, and the ventilation conditions may be totally different depending on the design of the ro-ro space.   This study was conducted in co-operation with RISE, the department of Fire Research, and the research project RO5. RO5 aims to clarify how the ventilation in ro-ro spaces affects the development of a fire and to possibly establish conceptual solutions for fire protection measures for ro-ro spaces with different ventilation conditions. The aim of this study is to explore tendencies of how both natural and mechanical ventilation affects the fire development within a ro-ro space. The intention is to provide basic knowledge regarding this subject, so that further simulations and tests could be optimized. The long-term goal of this study is to reduce the consequences, the severity and the number of fires within ro-ro spaces. The first step in the project is to explore the usefulness of two-zone models and compare the applicability of such method to experimental data. This is crucial in order to assess the applicability of two-zone models, especially as the aim is to make a parametric study of the influence of ventilation of fire development inside ro-ro space. A literature study of previous incident investigations of fires in ro-ro spaces was performed to gain knowledge concerning possible fire scenarios, ship constructions, fire development, consequences etc. and to provide an insight into how the ventilation was used in the case of a fire. In 2002, the research project “Model Scale Fire Tests on a Vehicle Deck Aboard a Ship” was issued by SP Swedish National Testing and Research Institute (now RISE). The aim was to simulate possible fire scenarios on a vehicle deck and examine what parameters can affect the fire development. To study this, tests were performed in model scale 1:8. The model had the dimensions 11.425 m x 2.786 m x 0.625 m (length x width x height). It was concluded that the ventilation and air supply being crucial for the fire development in ro-ro space. Although fires in a closed ro-ro space can quickly become ventilation-controlled, the fire may initially grow to be very large. One part of this study was to simulate some of the tests in “Model Scale Fire Tests on a Vehicle Deck Aboard a Ship” in the same sized model (scale 1:8). This was done since no tests on a full-scale model could be found. The simulation programs used were CFAST and B-RISK. The results were used for comparison to see how the two-zone simulations cohere with the tests. This was considered necessary due to limitations of the simulation programs and to the simplifications of two-zone fire model. By the comparison it was possible to choose the most suitable simulation program of the two, to use for further simulations in the study. The most suitable program was CFAST. Another part of the study was to conduct a parameter study. Since the model used in the tests in 2002 corresponded to an eight times larger model, the model was upscaled using Froude scaling to the dimensions 91.4 m x 22.3 m x 5 m (length x width x height). This model (scale 1:1) was then used in the parameter study. In the model, steel was used as material of the walls, ceiling and floor in order to imitate a real ro-ro space. By the results of the parameter study using two-zone fire simulations in CFAST, it is concluded that increased natural ventilation results in larger fire development, as well as increased mechanical ventilation results in larger fire development. Due to the results, open ro-ro spaces are recommended to be avoided. The regulations and definitions addressing closed ro-ro spaces are suggested to be reviewed since a closed ro-ro space can have relatively large natural ventilation. If natural ventilation is nevertheless required, the simulations indicate that openings constructed as wide as possible and with as low sill- and soffit height as possible are preferable. Because of the large size of a ro-ro space, there is enough oxygen to sustain a large fire during a given period. The fire will produce inert gases in the burning process such as CO2. As the gases reaches down to the fire source, the fire will start to fade. The oxygen within the ro-ro space will get pushed away by the process. The phenomenon is called inerting/vitiation and may occur when there is a fire within a ro-ro space. Previous investigations show that, the mechanical ventilation has been used to extract smoke in order to improve visibility and locate the fire. This measure may however be risky since mechanical ventilation may increase the fire development. Also, the mechanical ventilation may not be designed to be used for this purpose. In order to locate the fire efficiently for final extinguishment new improved and safer tactical methods is suggested to be evaluated. / Ett ro-ro fartyg är ett fartyg där fordon och annan last kan rullas på och av. Ombord på ett ro-ro fartyg finns det rorolastutrymmen. Ett rorolastutrymme är ett stort, korridorformat utrymme som vanligtvis är fyllt med fordon eller andra typer av last. Ett rorolastutrymme kan designas som ett öppet rorolastutrymme, ett slutet rorolastutrymme eller ett väderdäck. Det har skett flera brandincidenter på ro-ro fartyg och i rorolastutrymmen, samt har bränderna inträffat med en relativt hög frekvens. En brand på ett ro-ro fartyg är ett väldigt komplext fenomen. Brandutvecklingen är svår att förutse, och branden tenderar att växa väldigt fort. En viktig parameter för brandens utveckling är ventilationen. I ett rorolastutrymme kan ventilationsförhållandena vara väldigt olika beroende på hur utrymmet är utformat. Denna studie genomfördes tillsammans med RISE och forskningsprojektet RO5. RO5 syftar till att klargöra hur ventilationen i rorolastutrymmen påverkar brandutvecklingen, samt om möjligt, etablera konceptuella brandskyddsåtgärder för rorolastutrymmen med olika ventilationsförhållanden. Målet med denna studien är att studera tendenser av hur både naturlig och mekanisk ventilation påverkar brandutvecklingen i ett rorolastutrymme. Avsikten med denna studien är att få grundläggande kunskap inom ämnet, för att ytterligare simuleringar och kommande tester ska kunna optimeras i forskningsprojektet RO5. Det långsiktiga målet med studien är att minska konsekvenserna, brandstorleken, samt antalet bränder i rorolastutrymme. Metoden som användes i studien var tvåzonssimuleringar. För att få kunskap om möjliga brandscenarion, fartygskonstruktion, brandutveckling, konsekvenser etc. studerades tidigare olycksutredningar av bränder i rorolastutrymmen. Litteraturstudien gav också en inblick i hur ventilationen används vid händelse av brand i rorolastutrymmen. År 2002 utfördes “Model Scale Fire Tests on a Vehicle Deck Aboard a Ship” av SP, Sveriges Tekniska Forskningsinstitut (nuvarande RISE). Målet var att testa möjliga brandscenarion i ett rorolastutrymme och undersöka vilka parametrar som kan påverka brandens utveckling. Detta studerades genom att utföra tester i en nerskalad modell (skala 1:8). Modellen hade dimensionerna 11,425 m x 2,786 m x 0,625 m (längd x bredd x höjd). En slutsats var att ventilationen och syretillförseln var avgörande för brandens utveckling i ett rorolastutrymme. Även om branden i ett slutet rorolastutrymme snabbt kan bli ventilationskontrollerad, kan branden initialt bli väldigt stor. En del av studien var att simulera några av testerna som genomfördes i “Model Scale Fire Tests on a Vehicle Deck Aboard a Ship” i en modell av samma storlek (skala 1:8). Detta gjordes eftersom inga fullskaliga tester kunde hittas. De simuleringsprogram som användes var CFAST och B-RISK. Resultaten användes för att se hur simuleringarna stämde överens med verkliga tester. Detta bedömdes nödvändigt på grund av simuleringsprogrammens begränsningar och förenklingarna i tvåzonsmodellen. Genom jämförelsen kunde det mest lämpliga programmet av de två väljas ut för att använda i studiens fortsatta simuleringar. CFAST var det mest lämpliga programmet. En annan del av studien var att genomföra en parameterstudie. Eftersom modellen som användes i testerna 2002 motsvarar en åtta gånger så stor modell, skalades modellen upp med Froudes skalningslagar till dimensionerna 91,4 m x 22,3 m x 5 m (längd x bredd x höjd). Denna modellen (skala 1:1) användes därefter i en parameterstudie. För att modellen skulle efterlikna ett rorolastutrymme användes stål som väggar, tak och golv i modellen. Med resultaten från parameterstudien som utfördes i tvåzonssimuleringsprogrammet CFAST, kan slutsatsen dras att ökad naturlig ventilation resulterar i en större brandutveckling, samt att ökad mekanisk ventilation resulterar i en större brandutveckling. Baserat på resultaten rekommenderas det att öppna rorolastutrymmen bör undvikas. Definitionen för ett slutet rorolastutrymme föreslås att ses över eftersom ett slutet rorolastutrymme kan ha relativt mycket naturlig ventilation. Om naturlig ventilation dock krävs, indikerar simuleringarna på att öppningar konstruerade så breda som möjligt och med så låg sill- och bröstningshöjd som möjligt är att föredra. På grund av att rorolastutrymmen ofta är väldigt stora finns det tillräckligt med syre för att underhålla en stor brand under en viss tid. Branden kommer i förbränningsprocessen att producera inerta gaser som CO2 och när gaserna når ned till brandkällan kommer branden att börja avta. Syret i rorolastutrymmet kommer att tryckas bort av processen. Fenomenet kallas inertering/vitiation och kan förekomma vid en brand i ett rorolastutrymme. Tidigare utredningar visar på att mekanisk ventilation har använts för att ventilera ut rökgaser för att öka sikten och därmed kunna lokalisera branden. Denna åtgärd kan dock vara riskfull då mekanisk ventilation kan öka brandförloppet. Den mekaniska ventilationen är förmodligen inte heller designad för detta ändamål. För att kunna lokalisera en brand effektivt så att släckning kan genomföras, föreslås att nya, förbättrade och säkrare taktiker utvärderas.