Um dos parâmetros termo-hidráulicos de segurança mais importantes no projeto e operação de reatores a água pressurizada é o fluxo de calor crítico (FCC). O FCC ocorre quando se atinge uma região de instabilidade na mudança de mecanismo de transferência de calor de uma parede aquecida para um fluido, aumentado drasticamente a temperatura da parede. Transientes em um reator nuclear podem afetar a taxa de geração de calor ou a fluxo de refrigerante no núcleo, prejudicando a retirada de calor das varetas combustíveis. Conhecer o FCC nestas condições é essencial para evitar danos às varetas e, consequentemente, a liberação de material radioativo. O objetivo deste trabalho é analisar o FCC para o LABGENE (Laboratório de Geração Nucleoelétrica) por meio do planejamento experimental e da simulação de seções de teste em condições de operação utilizando o código COBRAIIIc/MIT-1 e a correlação EPRI para o FCC. Considerou-se primeiramente seções de teste 3×3 de dois tamanhos distintos e os resultados para 100 pontos experimentais foram mostrados por meio de superfícies de resposta, a fim de melhor visualizar e analisar o comportamento de FCC para cada condição. Dois pontos importantes são os valores máximo e mínimo do FCC encontrados. O valor máximo (1,038 MBtu/hr.ft2 ou 3,27 MW/m2) indica o fluxo de calor necessário para a realização dos experimentos e o mínimo (0,162 MBtu/hr.ft2 ou 0,51 MW/m2) indica a pior condição de operação, a qual estaria mais próxima do ponto de ebulição. As simulações e modificações no código foram verificadas utilizando o banco de dados da Universidade de Columbia. Foram selecionados 2718 pontos experimentais referentes a seções de teste 5×5 com perfil de potência uniforme. Os resultados foram apresentados pela razão entre o valor predito e o valor experimental (DNBR) e os limites de tolerância unilateral 95/95 foram calculados, estando dentro dos valores esperados. / One of the most important thermal-hydraulic safety parameters for pressurized water reactor design and operation is the critical heat flux (CHF). The CHF occurs when a region of instability reached in the change of heat transfer mechanism from a hot wall to a fluid is reached, dramatically increasing the wall temperature. Transients in a nuclear reactor can affect the heat generation rate or the coolant flow in the core, impairing the removal of heat from the fuel rods. Knowledge of the CHF on these conditions is essential to prevent fuel rod damages and therefore the release of radioactive material. The main goal of this work is to analyze the CHF for LABGENE (Nuclear-electrical Generation Laboratory) by an experimental design and test sections simulation in operating conditions by using COBRAIIIc/MIT-1 code and the EPRI correlation for CHF. 3x3 test sections were initially considered for two different heights and outcomes for 100 experimental points were shown by means of response surfaces in order to better visualize and analyze the behavior of CHF for each condition. Two important points are the maximum and minimum values of the CHF found. The maximum value (1.038 MW/m2 or 3.27 MBtu/hr.ft2) indicates the power required for the experiments and the minimum one (0.162 MBtu/hr.ft2 or 0.51 MW/m2) indicates the worst operation condition, which would be closer to the boiling point. Code simulations and modifications were verified using the CHF database of Columbia University. 2718 data points pertaining to test sections 5×5 with uniform power profile were selected. The results were presented by the ratio between the predicted value and the experimental value (DNBR) and the limits of unilateral tolerance 95/95 were calculated, being within the expected values.

Este estudo visou à utilização da tecnologia que emprega CO2 em estado supercrítico (SFE) para estudar a bioatividade dos diterpenos presentes no óleo de café verde, cafestol (C) e caveol (K), contudo propondo também a otimização de extração com líquido pressurizado (PLE) em batelada, utilizando para isto um Delineamento Composto Central Rotacional (DCCR2). O referido tema tem caráter inovador e inédito, já que a tecnologia de extração com líquido pressurizado, até então empregada para extração de analitos, passa a ser estudada em processos de extração de óleos vegetais tais como, óleo de pequi, óleo de café verde, extrato de sementes de pitanga no LTAPPN. Esta técnica utiliza solventes orgânicos e emprega elevada temperatura de extração, o que aumenta a capacidade de solubilização do solvente, e o emprego de altas pressões que acelera a difusão nos poros da matriz já que a viscosidade do solvente é diminuída. Este comportamento ocasiona maior penetração do solvente na matriz, aumentando sua capacidade de extração. A extração supercrítica (SFE) é uma tecnologia limpa, pois não emprega solventes orgânicos sendo promissora na obtenção de extratos enriquecidos com compostos bioativos que possam desempenhar alguma atividade. O estudo da atividade aguda dos diterpenos presentes no óleo de grãos de café verdes obtidos via SFE e PLE demonstrou que o óleo extraído com CO2 supercrítico, na dose de 2.000 mg/Kg no estudo de toxicidade aguda e nas doses de 25, 50 e 75 mg/Kg no estudo de toxicidade de doses repetidas, não apresentou letalidade aos animais, porém parâmetros bioquímicos, hematológicos e histológicos, apresentaram alterações. Todavia para aplicações do óleo de café verde em produtos desenvolvidos pelas indústrias farmacêuticas, alimentícias e/ou cosméticas, mais estudos de avaliação dos efeitos do óleo de café verde in vivo são necessários. Igualmente, o estudo de inovação tecnológica para obtenção de óleo de café verde visa obter extratos enriquecidos em diterpenos, evitando a degradação e tornando-os mais estáveis. Os resultados obtidos indicam que o óleo dos grãos de café verde extraídos via SFE e PLE (em batelada) possuem altas concentrações dos compostos ativos cafestol e caveol, sendo a condição de melhor rendimento a condição 4 (70º C e 8 min. ) a de maior rendimento de óleo 9,78%. / This study aimed to evaluate the bioactivity of the diterpenes in green coffee oil, cafestol (C), and kahweol (K) using supercritical fluid extraction (SFE- CO2), and to optimize the extraction with pressurized liquid extraction (PLE) in batch by using a rotatable central composite design (RCCD2). This issue has innovative and novel character, since the pressurized liquid extraction technology available until now for analyte extraction has been studied in vegetable oil extraction processes such as Pequi oil, green coffee oil, and Pitanga seeds extracts, at LTAPPN. This technique uses organic solvents and high extraction temperature, which increases the solvent solubilization capacity. The use of high pressure accelerates the diffusion rates into the pores of the matrix, due to the lower solvent viscosity. This behavior provides greater penetration of the solvent into the matrix, increasing solvent extraction capacity. The supercritical fluid extraction (SFE) is a clean technology as it does not employ organic solvents, besides being a promising alternative to obtain extracts enriched with bioactive compounds. The results of the acute activity of diterpenes in green coffee oil extracted by SFE and PLE showed that although no lethality was observed in the animals using the oil extracted by SFE at a dose of 2,000 mg / kg in an acute toxicity study, and 25, 50, and 75 mg / kg in a repeated dose toxicity study, changes were observed in biochemical, hematological, and histological parameters. However, more in vivo studies about the effects of green coffee oil are required for pharmaceutical, food, and cosmetic applications. Similarly, the technological innovation to obtain the green coffee oil aims at obtaining extracts enriched in diterpenes, preventing degradation and increasing stability. The results indicate that green coffee oil extracted by SFE and PLE (in batch) have high concentrations of the active compounds cafestol and kahweol, and the best extraction condition was the trial 4 (70 º C, and 8 min), and the highest oil yield was 9.78%.

Um dos parâmetros termo-hidráulicos de segurança mais importantes no projeto e operação de reatores a água pressurizada é o fluxo de calor crítico (FCC). O FCC ocorre quando se atinge uma região de instabilidade na mudança de mecanismo de transferência de calor de uma parede aquecida para um fluido, aumentado drasticamente a temperatura da parede. Transientes em um reator nuclear podem afetar a taxa de geração de calor ou a fluxo de refrigerante no núcleo, prejudicando a retirada de calor das varetas combustíveis. Conhecer o FCC nestas condições é essencial para evitar danos às varetas e, consequentemente, a liberação de material radioativo. O objetivo deste trabalho é analisar o FCC para o LABGENE (Laboratório de Geração Nucleoelétrica) por meio do planejamento experimental e da simulação de seções de teste em condições de operação utilizando o código COBRAIIIc/MIT-1 e a correlação EPRI para o FCC. Considerou-se primeiramente seções de teste 3×3 de dois tamanhos distintos e os resultados para 100 pontos experimentais foram mostrados por meio de superfícies de resposta, a fim de melhor visualizar e analisar o comportamento de FCC para cada condição. Dois pontos importantes são os valores máximo e mínimo do FCC encontrados. O valor máximo (1,038 MBtu/hr.ft2 ou 3,27 MW/m2) indica o fluxo de calor necessário para a realização dos experimentos e o mínimo (0,162 MBtu/hr.ft2 ou 0,51 MW/m2) indica a pior condição de operação, a qual estaria mais próxima do ponto de ebulição. As simulações e modificações no código foram verificadas utilizando o banco de dados da Universidade de Columbia. Foram selecionados 2718 pontos experimentais referentes a seções de teste 5×5 com perfil de potência uniforme. Os resultados foram apresentados pela razão entre o valor predito e o valor experimental (DNBR) e os limites de tolerância unilateral 95/95 foram calculados, estando dentro dos valores esperados. / One of the most important thermal-hydraulic safety parameters for pressurized water reactor design and operation is the critical heat flux (CHF). The CHF occurs when a region of instability reached in the change of heat transfer mechanism from a hot wall to a fluid is reached, dramatically increasing the wall temperature. Transients in a nuclear reactor can affect the heat generation rate or the coolant flow in the core, impairing the removal of heat from the fuel rods. Knowledge of the CHF on these conditions is essential to prevent fuel rod damages and therefore the release of radioactive material. The main goal of this work is to analyze the CHF for LABGENE (Nuclear-electrical Generation Laboratory) by an experimental design and test sections simulation in operating conditions by using COBRAIIIc/MIT-1 code and the EPRI correlation for CHF. 3x3 test sections were initially considered for two different heights and outcomes for 100 experimental points were shown by means of response surfaces in order to better visualize and analyze the behavior of CHF for each condition. Two important points are the maximum and minimum values of the CHF found. The maximum value (1.038 MW/m2 or 3.27 MBtu/hr.ft2) indicates the power required for the experiments and the minimum one (0.162 MBtu/hr.ft2 or 0.51 MW/m2) indicates the worst operation condition, which would be closer to the boiling point. Code simulations and modifications were verified using the CHF database of Columbia University. 2718 data points pertaining to test sections 5×5 with uniform power profile were selected. The results were presented by the ratio between the predicted value and the experimental value (DNBR) and the limits of unilateral tolerance 95/95 were calculated, being within the expected values.

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are two structurally related groups of chemicals, generally referred to as `dioxins´. These are of great concern due to their high toxicity and global spread. Other groups of compounds with similar chemical structure and toxicity mechanisms are the brominated analogues polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs), and the dioxin-like polychlorinated biphenyls (PCBs). Numerous studies have been undertaken to investigate sources and transport routes of dioxins. However, much remains to be done, including analytical, inventories of dioxin-like compounds, such as PBDD/Fs, and the development of more convenient analytical methods. The currently standard procedure for analyzing dioxins (and dioxin-like compounds) is to use Soxhlet extraction followed by multi-step clean-up and gas chromatography - high resolution mass spectrometry (GC- HRMS) for detection. Unfortunately, this method is very solvent, labor and time-consuming, making it very expensive. The main aim of the studies this thesis was to develop pressurized liquid extraction (PLE) with integrated clean up techniques for fast, convenient preparation of dioxin samples. PLE with integrated clean-up has previously been used for extracting dioxins from biological samples, but in these studies the possibility of extending its use to abiotic samples was explored. The results show that PLE with an integrated carbon trap is suitable for analyzing dioxins in various types of soil samples, sediment and flue gas samples. The results also showed that it has potential for analyzing dioxins in fly ash. The thesis focuses on developments of the methodology for dioxin analysis, but also includes results obtained from PBDDs and dioxin-like PCB analyses. In addition, the possibility of using various other kinds of detection techniques rather than GC-HRMS, such as enzyme-linked immunosorbent assays (ELISAs) or two-dimensional gas chromatography with micro electron capture detection (GCxGC-µECD) was explored. The results indicate that ELISA and GCxGC-µECD could serve as complementary detection systems in some cases. However, it is not yet possible to fully replace GC-HRMS. A further refinement of the PLE with in-cell clean-up technique is the modular approach developed in these studies. With this technique it is possible to include various steps for both clean-up and fractionation. For example, sulphuric acid impregnated silica could be combined with active carbon for the simultaneous removal of lipids (along with other interferences) and fractionation of PCBs and PCDD/Fs. It was shown that the method could provide data that agreed reasonably well with both reference values and values obtained using traditional methods. In general PLE proved to have high extraction efficiency and to yield very similar congener profiles to the reference method. In addition, it was shown that it allowed one-step extraction and clean-up of a salmon sample. Such single-step procedures are the ultimate goals for any extraction technique, and it would be highly desirable to develop one-step methods that could be extended to other types of samples. For the rest of the matrices tested (soil, sediment, mussel and crab tissue and flue gas) the method was successful, however a final polishing step is currently required, involving either dilution or clean-up using miniaturized multilayer silica columns, to obtain extracts that are pure enough for GC-HRMS analysis. Using the developed modular-PLE system substantial costs could be saved. It was estimated that the method could reduce the cost of preparing samples by up to 90%, which would greatly facilitate large-scale inventories.

Naphthenic acids (NAs) are toxic organic acid compounds released during the caustic hot-water extraction of crude oil from oil sands in north-eastern Alberta, Canada. NAs subsequently accumulate in the large volume of oil sands process water (OSPW) produced daily by oil sands operations. The complexity of dealing with a mixture of over 200 individual NA compounds, combined with their acute aquatic toxicity and large volume of production has made them an emerging pollutant of concern for western Canada. The following thesis outlines a variety of experiments designed to determine the potential to use wetland plants to enhance the dissipation of NAs from OSPW (phytoremediation). <p>Investigations were carried out with three native emergent macrophyte species cattail (<i>Typha latifolia</i>), common reed (<i>Phragmites australis </i>subsp. <i>americanus</i>), and hard-stem bulrush (<i>Scirpus acutus</i>) to see if they enhanced the dissipation of NAs from a hydroponic system. Dissipation of NAs (at 30 mg L-1 and 60 mg L-1) was investigated with both a commercially available NA mixture as well as with a NA mixture extracted from the OSPW. Dissipation of NAs was also investigated under the different ionized forms of NAs (ionized, pH = 7.8; and non-ionized, pH = 5.0) to better elucidate the mechanisms of NA uptake and toxicity in plants. Phytotoxicity of NAs was investigated in hydroponic experiments through fresh weight gain and evapotranspiration was monitored throughout the experiment by water uptake. Commercially available NA mixture was more phytotoxic than oil sands NAs mixture. As well, NAs were found to be more phytotoxic in their non-ionized form therefore indicating that they may be taken up through an ion-trap‟ mechanism. However despite this, no significant dissipation of total NAs was observed from planted hydroponic systems. Nevertheless there was a significant change in the distribution (percent abundance) of individual NA families of certain size. These changes were related to the one- and two-ring NA compounds (Z = -2 and Z = -4). Despite not detecting any dissipation of total NAs from the systems, plants were able to reduce the toxicity of a NA system over 30 days by 45% as determined by Daphnia magna acute toxicity bioassays; a 11% greater reduction than unplanted systems.<p> Studies were also conducted investigating the microbial community inhabiting cattail roots exposed to NAs. It was observed that the rhizosphere community changed with NA exposure, with a general increase in potentially pathogenic bacteria and a decrease in bacteria previously found to be beneficial to plant growth. The observed microbial community change could be an indirect effect of the Phytotoxicity experienced by aquatic macrophytes exposed to NAs. Synchrotron-sourced, fourier transform microspectroscopy analysis of root cross sections revealed that there were significant physiological changes to those roots exposed to NAs. These changes were identified as being cell death in the plant root epidermis as well as a change in the chemistry of parenchyma cells in the root pith. It is not known if these changes are a direct effect of NAs to the plant or due to changes of the associated rhizosphere community in the roots or some combination of both these factors.

Naphthenic acids (NAs) are toxic organic acid compounds released during the caustic hot-water extraction of crude oil from oil sands in north-eastern Alberta, Canada. NAs subsequently accumulate in the large volume of oil sands process water (OSPW) produced daily by oil sands operations. The complexity of dealing with a mixture of over 200 individual NA compounds, combined with their acute aquatic toxicity and large volume of production has made them an emerging pollutant of concern for western Canada. The following thesis outlines a variety of experiments designed to determine the potential to use wetland plants to enhance the dissipation of NAs from OSPW (phytoremediation). <p>Investigations were carried out with three native emergent macrophyte species cattail (<i>Typha latifolia</i>), common reed (<i>Phragmites australis </i>subsp. <i>americanus</i>), and hard-stem bulrush (<i>Scirpus acutus</i>) to see if they enhanced the dissipation of NAs from a hydroponic system. Dissipation of NAs (at 30 mg L-1 and 60 mg L-1) was investigated with both a commercially available NA mixture as well as with a NA mixture extracted from the OSPW. Dissipation of NAs was also investigated under the different ionized forms of NAs (ionized, pH = 7.8; and non-ionized, pH = 5.0) to better elucidate the mechanisms of NA uptake and toxicity in plants. Phytotoxicity of NAs was investigated in hydroponic experiments through fresh weight gain and evapotranspiration was monitored throughout the experiment by water uptake. Commercially available NA mixture was more phytotoxic than oil sands NAs mixture. As well, NAs were found to be more phytotoxic in their non-ionized form therefore indicating that they may be taken up through an ion-trap‟ mechanism. However despite this, no significant dissipation of total NAs was observed from planted hydroponic systems. Nevertheless there was a significant change in the distribution (percent abundance) of individual NA families of certain size. These changes were related to the one- and two-ring NA compounds (Z = -2 and Z = -4). Despite not detecting any dissipation of total NAs from the systems, plants were able to reduce the toxicity of a NA system over 30 days by 45% as determined by Daphnia magna acute toxicity bioassays; a 11% greater reduction than unplanted systems.<p> Studies were also conducted investigating the microbial community inhabiting cattail roots exposed to NAs. It was observed that the rhizosphere community changed with NA exposure, with a general increase in potentially pathogenic bacteria and a decrease in bacteria previously found to be beneficial to plant growth. The observed microbial community change could be an indirect effect of the Phytotoxicity experienced by aquatic macrophytes exposed to NAs. Synchrotron-sourced, fourier transform microspectroscopy analysis of root cross sections revealed that there were significant physiological changes to those roots exposed to NAs. These changes were identified as being cell death in the plant root epidermis as well as a change in the chemistry of parenchyma cells in the root pith. It is not known if these changes are a direct effect of NAs to the plant or due to changes of the associated rhizosphere community in the roots or some combination of both these factors.

Managed Pressure Drilling now at the pinnacle of the 'Oil Well Drilling' evolution tree, has itself been coined in 2003. It is an umbrella term for a few new drilling techniques and some preexisting drilling techniques, all of them aiming to solve several drilling problems, including non-productive time and/or drilling flat time issues. These techniques, now sub-classifications of Managed Pressure Drilling, are referred to as 'Variations' and 'Methods' of Managed Pressure Drilling. Although using Managed Pressure Drilling for drilling wells has several benefits, not all wells that seem a potential candidate for Managed Pressure Drilling, need Managed Pressure Drilling. The drilling industry has numerous simulators and software models to perform drilling hydraulics calculations and simulations. Most of them are designed for conventional well hydraulics, while some can perform Underbalanced Drilling calculations, and a select few can perform Managed Pressure Drilling calculations. Most of the few available Managed Pressure Drilling models are modified Underbalanced Drilling versions that fit Managed Pressure Drilling needs. However, none of them focus on Managed Pressure Drilling and its candidate selection alone. An 'Managed Pressure Drilling Candidate Selection Model and software' that can act as a preliminary screen to determine the utility of Managed Pressure Drilling for potential candidate wells are developed as a part of this research dissertation. The model and a flow diagram identify the key steps in candidate selection. The software performs the basic hydraulic calculations and provides useful results in the form of tables, plots and graphs that would help in making better engineering decisions. An additional Managed Pressure Drilling worldwide wells database with basic information on a few Managed Pressure Drilling projects has also been compiled that can act as a basic guide on the Managed Pressure Drilling variation and project frequencies and aid in Managed Pressure Drilling candidate selection.

Es wurde ein Modell zur realistischen Beschreibung der Kühlmittelvermischung innerhalb des Reaktordruckbehälters von Druckwasserreaktoren in den gekoppelten Programmkomplex DYN3D/ATHLET implementiert. Diese Modell basiert auf dem Prinzip der linearen Superposition Dirac-Impuls-ähnlicher Störungen und kann für die Modellierung der Vermischung von Kühlmittel unterschiedlicher Temperatur und/oder unterschiedlicher Borsäurekonzentration eingesetzt werden. Der um das Vermischungsmodell erweiterte Programmkomplex DYN3D/ATHLET wurde für Analyse von Borverdünnungsstörfällen und Frischdampflecks angewandt. Für den Fall "Start der ersten Hauptkühlmittelpumpe bei Vorhandensein eines minderborierten Pfropfens im kalten Strang" zeigten die Ergebnisse der durchgeführten Parameterstudie, dass es selbst bei Annahme des maximal möglichen Pfropfenvolumens nicht zu einer Schädigung des Brennstoffes kommt. Mit den Analysen zu einem generischen Frischdampfleckszenario wurde die Anwendbarkeit des Programmkomplexes DYN3D/ATHLET auf die zweite Störfallklasse, in der die Kühlmittelvermischung eine wichtige Rollen spielt, demonstriert. Im Rahmen der Arbeiten zum Projekt wurde außerdem gezeigt, dass der Einfluss der turbulenten Schwankungen des Geschwindigkeitsfeldes innerhalb des Reaktordruckbehälters auf neutronenkinetische Parameter im Nominalbetrieb und unter Störfallbedingungen nicht zu vernachlässigen ist. A model for the realistic description of the coolant mixing inside the pressure vessel of pressurized water reactors was implemented into the coupled code complex DYN3D/ATHLET. This model is based on the linear superposition Dirac-pulse-like perturbations. The model can be applied to the mixing of coolant of different temperature and/or boron concentration. The coupled code complex DYN3D/ATHLET with the newly implemented model was applied to the analysis of boron dilution and steam line break accidents. The results of a parameter study for the case "Start-up of the first main coolant pump with a slug of lower borated water in the cold leg" have shown, that even under the conditions of the maximum slug volume there is no fuel damage. The applicability to the second class of accidents, where the coolant mixing has to be considered, was demonstrated by the analysis of a generic main steam line break scenario. Further it was shown, that the influence of turbulent fluctuations of the velocity inside the reactor pressure vessel during nominal and accident conditions on neutron-kinetic parameters cannot be neglected.

Au sens de la législation, les compléments alimentaires sont des denrées alimentaires et doivent donc subir un traitement de pasteurisation pour détruire les microorganismes potentiellement pathogènes. L’utilisation du CO2 comprimé peut être une alternative basse température aux traitements thermiques classiques. Dans ce travail, la technologie au CO2 est optimisée pour traiter des compléments alimentaires fortement chargés par trois microorganismes.L’impact des conditions expérimentales sur l’inactivation et la préservation des actifs a été mis en évidence via un plan d’expériences de type composite centré. La température et dans une moindre mesure l’interaction pression-durée ont été identifiés comme étant les facteurs les plus influents. Pour les actifs, la teneur en polyphénols totaux est préservée alors que la vitamine C est conservée à plus de 70%. Les résultats ont été analysés au regard de l’effet de la température et de la pression sous azote et sous air, de l’interaction pH/température, de la charge en microorganismes et de la nature de la matrice.La pasteurisation est également examinée sous l’angle du transfert de masse et des temps caractéristiques dans un contacteur gaz-liquide afin d’estimer la cinétique de dissolution du CO2 dans la matrice. L’étude de sensibilité montre que c’est la solubilité du CO2 dans l’eau qui impacte la cinétique de dissolution plus que les paramètres liés au contacteur. Des essais avec deux dispositifs batch et un mini-dispositif continu illustrent ce propos.La durée de vie des produits ainsi pasteurisés et l’apport du traitement CO2 comparé à un traitement thermique ont été aussi étudiés. / According to the law, food dietary supplements belong to food products and must then be pasteurized to kill potentially pathogenic microorganisms. Pressurized carbon dioxide can be a low-temperature alternative to usual thermal treatments. In this study, a high pressure carbon dioxide process is optimized to pasteurize dietary supplements highly contaminated with 3 microorganism species.This work reviews the effect of operating parameters on microbial inactivation and active ingredients thanks to a central composite design. Temperature and, at a lower extent, the pressure-duration interaction were identify as influent. Concerning active ingredients, total phenolic concentration is fully preserved whereas vitamin C retention rate is at least of 70%. Results were analyzed taking into account the synergistic effect of temperature and pH, temperature and atmospheric or N2 pressure, contamination level and the composition of the food matrix.Pasteurization was evaluated from the mass transfer and characteristic times point of view in a gaz-liquid contactor. The sensitivity analysis underlines that CO2 solubility in water is the main factor that affects the dissolution kinetic, beyond contactor constraints. Experiments led with 2 different batch set-ups and a mini‑continuous reactor illustrate that point.Finally this work studies the shelf-life of our CO2-pasteurized products and estimates the added value of such a treatment compared to a thermal one.

This report is a bachelor thesis at Karlstad University in collaboration with Invencon AB and Ranotor AB. The goal was to analyze a rotating valve leading water vapor through an inlet and five outlets. The quantifiable results that were addressed in this project are the mass flow through the outlets and the forces affecting the valve and its shaft (primarily radial forces). The tools used for this project are PTC Creo and ANSA for modelling and mesh as well as ANSYS-CFX and Matlab for computational help. The results show that the specified rotational speed of 4600 rpm doesn’t work for this model. The rotational speed was chosen because of an interest in this specific operating condition. A 3 mm radial gap between the rotating valve and the valve housing proved to cause a leakage in the form of pressure loss inside the valve. The boundary conditions that were laid out for this project are not valid for this operating condition. Since the difference in pressure is large (100 down to 1 bar) the flow is choked. A large difference in pressure also makes it important to adjust the total area of the outlets, since the pressure drop affects the density of the vapor. The forces on the rotating valve that were calculated (using ANSYS-CFX) create a foundation for choosing bearings for the valve. If the construction is modified, and/or the rotating valve will operate at a different rotational speed these forces will be subject to change. / Denna rapport är ett examensarbete på Karlstads Universitet i samband med Invencon AB och Ranotor AB. Målet var att analysera en roterande ventil som leder trycksatt vattenånga via ett inlopp och ut genom fem olika utlopp. De kvantifierbara resultaten som söktes var massflödet ut ur utloppen och krafterna som påverkar ventilen och axeln (främst radiellt). Verktyg som har använts för att analysera ventilen är PTC Creo och ANSA för modellering och mesh, samt ANSYS-CFX och Matlab för beräkningshjälp. Resultaten tyder på att det valda varvtalet, 4600 rpm, inte fungerar så bra. Varvtalet valdes pågrund av att man var intresserad av driftsfallet. Ett 3 mm radiellt avstånd mellan ventil ochventilhus visade sig även ge läckage i form av tryckfall inuti ventilen. Randvillkoren som är specificerade är inte giltiga vid detta driftsfall. Eftersom tryckförhållandet är så högt (100 till 1 bar) så är flödet chokat. Stor tryckskillnad gör det viktigt att anpassa arean på utloppen, då tryckfall påverkar densiteten. Krafterna på den roterande ventilen som beräknades (i ANSYS-CFX) är ett underlag vid val av lager för ventilen. Om konstruktionen modifieras, och/eller ventilen kommer att användas vid ett annat varvtal så kommer dessa krafter att ändras.