Polycrystalline silicon photovoltaic (PV) modules have the advantage of lower manufacturing cost as compared to their monocrystalline counterparts, but generally exhibit both lower initial module efficiencies and more significant early-stage efficiency degradation than do similar monocrystalline PV modules. For both technologies, noticeable deterioration in power conversion efficiency typically occurs over the first two years of usage. Estimating PV lifetime by examining the performance degradation behavior under given environmental conditions is, therefore, one of continual goals for experimental research and economic analysis. In the present work, accelerated lifecycle testing (ALT) on three polycrystalline PV technologies was performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability, providing an illumination uniformity of 98% over a 2 x 1.6m area. In order to investigate environmental aging effects, time-dependent PV performance (I-V characteristic) was evaluated over a recurring, compressed day-night cycle, which simulated local daily solar insolation for the southwestern United States, followed by dark (night) periods. During a total test time of just under 4 months that corresponded to a year equivalent exposure on a fielded module, the temperature and humidity varied in ranges from 3 degrees C to 40 degrees C and 5% to 85% based on annual weather profiles for Tucson, AZ. Removing the temperature de-rating effect that was clearly seen in the data enabled the computation of normalized efficiency degradation with time and environmental exposure. Results confirm the impact of environmental conditions on the module long-term performance. Overall, more than 2% efficiency degradation in the first year of usage was observed for all thee polycrystalline Si solar modules. The average 5-year degradation of each PV technology was estimated based on their determined degradation rates.

No description available.

Le processus de retrait-gonflement des sols argileux est à l'origine des dommages au bâti durant les périodes de sécheresse. Dans cette thèse, les processus de retrait-gonflement de deux formations de sol argileux en France qui sont les Argiles Plastiques du Sparnacien et l'argile d'Héricourt du Lias sont étudiés à différentes échelles et différents états (intact, remanié, compacté et traité à la chaux) en considérant spécialement le rôle de la microstructure. Pour ce faire, une partie de la recherche est réalisée sur la caractérisation des sols étudiés pour analyser leurs propriétés minéralogiques, microstructurales, géotechniques et hydriques par rapport à leur propriété de retrait-gonflement. La deuxième partie de la recherche est consacrée à l'analyse des processus de gonflement, de retrait, de fissuration des sols au cours d'un cycle simple ou de cycles répétés d'humidification-séchage à l'échelle de l'éprouvette. Les processus de retrait-gonflement de sol à une échelle plus grande sont étudiés dans la troisième partie en réalisant les essais d'infiltration et d'évaporation dans une chambre environnementale. Les résultats obtenus mettent en évidence les différences de comportement au retrait-gonflement pour différents états des sols étudiés. Les minéraux argileux ainsi que le quartz, les carbonates et des hydrates, mais aussi la microstructure des sols contrôlent ces phénomènes de retrait-gonflement lors des échanges hydriques. Tous les changements de volume de sol argileux au cours de gonflement-retrait sont gouvernés principalement par la famille de pores inter-agrégats naturels. Ces résultats sont apportés par les analyses microstructurales porosimétriques et au MEB. / The shrink-swell process of clayey soils is causing damage to the structures during periods of drought. In this thesis, the shrink-swell process of two clayey soils in France that are the Plastic Clays of Sparnacian age and Héricourt clay of Lias is studied at different scales and different conditions (intact, remoulded, compacted and lime treated) by insisting on the role of microstructure. To do this, a part of the study is carried out on the characterisation of soils studied to analyse their mineralogical, microstructural, geotechnical and hydraulic properties in relation with their shrink-swell property. The second part of the study focuses on the analysis of swelling, shrinkage, cracking processes of soil during a single cycle or repeated wetting-drying cycles at specimen scale. The shrink-swell process of soil at a larger scale is studied in the third part by performing infiltration and evaporation tests in the environmental chamber. The results highlight the difference in the shrink-swell behavior at different conditions of soils studied and emphasize the importance of the presence and nature of clay minerals also quartz, hydrates and microstructure of soil to the shrinkage and swelling during water exchange. All changes in the volume of clayey soil during shrinkage and swelling are mainly governed by natural inter-aggregate pores, which are showed by microstructural analyses of MIP and SEM tests.

Secondary organic aerosols (SOA) comprise a substantial fraction of the total global aerosol budget. While laboratory studies involving smog chambers have advanced our understanding of the formation mechanisms responsible for SOA, our knowledge of the processes leading to SOA production under ambient gaseous and particulate concentrations as well as the impact these aerosol types have on climate is poorly understood. Although the majority of atmospheric aerosols scatter radiation either directly or indirectly by serving as cloud condensation nuclei, soot is thought to have a significant warming effect through absorption. Like inorganic salts, soot may undergo atmospheric transformation through the vapor condensation of non-volatile gaseous species which will alter both its chemical and physical properties. Typical smog chamber studies investigating the formation and growth of SOA as well as the soot aging process are temporally limited by the initial gaseous concentrations injected into the chamber environment. Furthermore, data interpretation from such experiments is generally restricted to the singular gaseous species under investigation. This dissertation discusses the use of a new aerosol chamber designed to study the formation and growth of SOA and soot aging under atmospherically relevant conditions. The Ambient Aerosol Chamber for Evolution Studies (AACES) was deployed at three field sites where size and hygroscopic growth factor (HGF) of ammonium sulfate seed particles was monitored over time to examine the formation and growth of SOA. Similar studies investigating the soot aging process were also conducted in Houston, TX. It is shown that during the ambient growth of ammonium sulfate seed particles, as particle size increases, hygroscopic growth factors decrease considerably resulting in a significant organic mass fraction in the particle phase concluding an experiment. Observations of soot aging show an increase in measured size, HGF, mass and single scattering albedo. Ambient growth rate comparisons with chamber growth yielded similar trends verifying the use of AACES to study aerosol aging. Based on the results from this study, it is recommended that AACES be employed in future studies involving the production and growth of SOA and soot aging under ambient conditions in order to bridge the gaps in our current scientific knowledge.

No description available.

Il est bien connu que l'évaporation d'eau joue un rôle essentiel dans l'interaction entre le sol et l'atmosphère. Pendant le processus d'évaporation, le comportement thermo-hydro-mécanique des sols change, engendrant ainsi des problèmes préoccupants. Ceci peut concerner différents domaines comme l'agronomie, l'hydrologie, la science des sols, la géotechnique, etc. Par conséquent, il est essentiel d'étudier les mécanismes d'évaporation de façon approfondie. Cette étude porte sur les mécanismes d'évaporation dans des conditions atmosphériques contrôlées. Le sable de Fontainebleau et l'argile d'Hércourt utilisée pour la construction du remblai expérimental dans le cadre du projet ANR TerDOUEST (Terrassements Durables - Ouvrages en Sols Traités, 2008-2012) ont été étudiés à cet effet. Une chambre environnementale (900 mm de haut, 800 mm de large et 1000 mm de long) équipée de différents capteurs a d'abord été développée, permettant un suivi complet des paramètres concernant l'atmosphère et le sol au cours d'évaporation. Quatre essais expérimentaux ont été réalisés sur le sable de Fontainebleau compacté à une densité sèche de 1,70 Mg/m3, avec une nappe phréatique constante au fond de l'échantillon, et sous différentes conditions atmosphériques (différentes valeurs de l'humidité relative de l'air, de la température et du débit d'air). La pertinence du système a été mise en évidence par la bonne qualité des résultats. La température de l'air à l'intérieur de la chambre a été trouvée affectée par la température du tube de chauffage, le débit d'air et l'évaporation d'eau; la température du sol est fortement affectée par les conditions atmosphériques et l'état d'avancement de l'évaporation ; l'humidité relative dans la chambre diminue au cours du temps et son évolution peut être considérée comme un indicateur du processus d' évaporation ; la teneur en eau volumique dans la zone proche de la surface est fortement influencée par le processus d'évaporation et présente une relation linéaire avec la profondeur ; la succion du sol diminue avec la profondeur et augmente au fil du temps ; le taux d'évaporation est fortement affecté par les conditions de l'air en particulier dans la phase initiale de vitesse d'évaporation constante. Après les essais sur le sable de Fontainebleau, l'échantillon de l'argile d'Hércourt compactée à une densité sèche de 1,40 Mg/m3 a été soumis à une infiltration d'eau afin d'étudier ses propriétés hydrauliques. Pour obtenir un meilleur aperçu du mécanisme d'évaporation pour l'argile, deux essais d'évaporation sur l'argile d'Hércourt compactée avec une nappe phréatique constante au fond de l'échantillon ont été effectuées sous des conditions atmosphériques contrôlées. Les résultats permettent de comprendre les mécanismes d'évaporation en cas de fissuration due à la dessiccation. En outre, afin d'étudier les mécanismes d'évaporation potentiels, des essais avec une couche d'eau libre ont été également réalisés en faisant varier la vitesse du vent et la température de l'air. L'initiation et la propagation de fissures de dessiccation pendant le processus d'évaporation et son effet sur l'évaporation ont également été étudiés par la technique de traitement d'image. En termes de modélisation, le taux d'évaporation potentiel a été modélisé à travers l'évaluation des modèles existants et des modèles combinés. Il apparait que le modèle développé par Ta (2009) est le plus approprié. Le taux d'évaporation réelle depuis le sable a été ensuite analysé. Il semble important de considérer l'avancement du front sec pendant le processus d'évaporation pour les sols sableux. Pour l'argile d'Héricourt, une bonne prévision a été également obtenue en utilisant un modèle qui tient compte de l'effet des fissures de dessiccation / As a well-known phenomenon, soil water evaporation plays an important role in the interaction between soil and atmosphere. Water evaporates during this process resulting in changes of soil thermo-hydro-mechanical behavior and in turn causing problems in different domains such as agronomy, hydrology, soil science, geotechnical engineering, etc. Therefore, it is essential to investigate the soil water evaporation mechanisms in depth.This study deals with the soil water evaporation mechanisms under controlled atmospheric conditions. The Fontainebleau sand and the Hércourt clay used for the construction of the experimental embankment with the ANR project TerDOUEST (Terrassements Durables - Ouvrages en Sols Traités, 2008 - 2012) were used in this investigation. A large-scale environmental chamber system (900 mm high, 800 mm large and 1000 mm long) equipped with various sensors was firstly developed, allowing a full monitoring of both atmospheric and soil parameters during the evaporation process. Four experimental tests were carried out on the Fontainebleau sand compacted at 1.70 Mg/m3 dry density with a steady water table at soil bottom under different atmospheric conditions (different values of air relative humidity, temperature and air flow rate). The performance of the environmental chamber system in investigating soil water evaporation was evidenced by the quality and the relevance of results. The air temperature inside the chamber was found to be affected by the heating tube temperature, the air flow rate and the soil water evaporation process; the soil temperature was strongly affected by the air conditions and the evaporation progress; the relative humidity in the chamber was decreasing during the evaporation progress and its evolution could be considered as an indicator of the evaporation progress; the volumetric water content in the near-surface zone was strongly affected by the evaporation process and exhibited a linear relationship with depth; the soil suction was decreasing over depth and increasing over time; the evaporation rate was strongly affected by the air conditions especially at the initial constant evaporation rate stage. After the tests on the Fontainebleau sand, the Hércourt clay sample compacted at 1.40 Mg/m3 dry density was subjected to an infiltration experiment for investigating its hydraulic properties. To get a better insight into the water evaporation mechanism for clay, two compacted Hércourt clay evaporation tests with a steady water table at bottom were carried out under controlled atmospheric conditions. The results allow understanding the evaporation mechanisms in case of desiccation cracks. Furthermore, in order to investigate the potential evaporation mechanisms, tests with a free water layer was also conducted with varying wind speed and air temperature. The initiation and propagation of desiccation cracking during the evaporation process and its effect on water evaporation were also investigated by the digital image processing technique. In terms of modeling, the potential evaporation rate was first modeled through evaluation of the existing models and the combined models. It reveals that the model developed by Ta (2009) is the most appropriate one. The actual evaporation rate for sand was then analyzed. It appears important to consider the progress of the dry front during the evaporation process for sandy soils. For the Héricourt clay, good simulation was also obtained using a model that accounts for the effect of desiccations cracks

La sensibilisation du grand public à la pollution intérieure, les exigences croissantes des réglementations/recommandations le tout combiné à une nécessité de se démarquer de la concurrence, font de la limitation de la concentration des COV (COV : Composés Organiques Volatiles) dans l’air habitacle un enjeu crucial pour l’industrie automobile. En effet, à l’intérieur des véhicules, les COV sont principalement issus de l’air extérieur par combustion et évaporation du carburant mais, contrairement aux autres polluants, peuvent également avoir une origine intérieure à l’habitacle de par la désorption de substances chimiques utilisées lors de la fabrication des matériaux présents dans le véhicule. La capture des COV par adsorption sur charbons actifs ou zéolithes est à ce jour l’une des techniques d’abattement des COVs les plus efficaces et les moins coûteuses mais souffre de certaines limitations (sélectivité, régénération). L’objectif de cette thèse a consisté à étudier une alternative avec l’emploi d’une autre classe d’adsorbants ‘hybrides’ : les Metal-Organic Frameworks (MOFs). Formés de briques inorganiques connectées par des ligands organiques, ces matériaux poreux cristallisés présentent une grande diversité structurale ainsi qu’une composition chimique (métal, ligand) et une porosité (taille des pores, surface spécifique et volume poreux) extrêmement modulables. Cela vient de la possibilité quasi-infinie de faire varier à la fois le centre métallique et le ligand organique, ce que l’on ne retrouve pas à cette échelle chez les zéolithes et les charbons actifs. Le travail a consisté à évaluer les performances d’une série d’une dizaine de MOFs, possédant des propriétés chimiques (acidité, redox, hydrophiles/hydrophobes, …) et structurales (taille et forme des pores, réseaux rigides ou flexibles…) différenciées mais aussi de leur stabilité avérée (eau, température) et mise à l’échelle déjà établie. En plus des caractérisations usuelles (diffraction des rayons X, analyse thermogravimétrique, spectroscopie Infra-Rouge, porosimétrie N2 à 77K), la spectroscopie Infra-Rouge operando a été utilisée pour simuler le comportement de ces MOFs en présence de COV dans des conditions aussi proches que possible de la réalité. Les adsorbants les plus prometteurs ont ensuite été mis à l’échelle (50-100 g) et mis en forme (pastilles) puis testés en chambre de simulation environnementale. / The indoor air pollution awareness of general public and the increasing demands of regulations / recommendations, combined with a need to stand out from the competition, make limiting the concentration of VOCs (VOCs : volatile organic compounds ) in the air cockpit crucial for the automotive industry. For example, inside a vehicle, the VOCs are originated from the outside air by combustion and evaporation of fuel. However, unlike other pollutants, it may also have an inner origin from the desorption of existing chemical substances used in the manufacture of the vehicle. Thus, the capture of VOCs by adsorption is one of the challenging techniques today. In this context, activated carbon and zeolite based VOC abatement are effective and least expensive but suffers some limitations in stability, selectivity and regeneration. The aim of this thesis was to study an alternative class of 'hybrid' adsorbents i.e. Metal-Organic Frameworks (MOFs). These porous crystalline materials are built by the association of inorganic bricks connected by organic ligands. They have highly tunable structural diversity,chemical composition (metal:ligand) and porosity (pore size, surface area and pore volume). Moreover, they possess almost infinite ability to vary both the metal center and the organic ligand that is not found at this level in zeolites and activated carbons. The work was to evaluate the performance of a series of ten MOFs, having diverse architecture (size and shape of the pores, rigid or flexible networks ...), chemical properties (acidity, redox, hydrophilic / hydrophobic, ...) and stability (water temperature). In addition to the usual characterization (X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, porosimetry N2 at 77K), Infra-Red spectroscopy operando was performed to simulate the behavior of these MOFs in the presence of VOCs in conditions as close as possible to the reality. Furthermore, the most promising adsorbents were scaled up (50-100 g) and formatted/fabricated as pellets and tested for environmental simulation chamber.

In spite of significant reduction of cost associated with launching a spacecraft, launching deep space exploratory missions are yet to be accessible to most universities and researchers. A solution to testing scientific hypotheses and verifying technologies for space is the use of environmental chambers, also know as space simulators, - vacuum chambers, which replicate the space environment. The scope of this thesis project is to develop a thermal control system for a space simulator, which would replicate the environment on Mars, and allow for controlled carbon dioxide ice deposition experiments. The first part of the thesis looks at the climate on Mars, and the process behind the carbon dioxide ice cycle, gives a description of the systems in a space simulator. Then the requirements of a thermal system for the space simulator are stated. The second part of the thesis gives a brief overview of the previous solution attempts at the laboratory in Luleå University of Technology, and the manufacturing technologies required to make them. Based on that, a design justification is given. The thermal control system design section gives an overall design description, with detailed report on the iterative design of the sample holders, and thermal simulations results. Additive manufacturing is analyzed, as means of producing solid designs with the necessary performance targets. The overall cost of the designed thermal control system is calculated, and further work directions are proposed. The appendices include the literature used, the technical drawings for manufacturing and assembly of the thermal system, detailed budget calculations, and additional data from the thermal analysis.

No description available.

<p>This study is focused on the design, production, and operation of a controlled environmental olfaction chamber to evaluate human physiological and emotional response to volatile chemical emissions (VCPs) from scented household products in addition to careful characterization of the volatile organic compounds (VOCs) present in these product emissions. Utilizing proton transfer reaction time-of-flight mass spectrometry, the chamber can collect VCP emissions and identify VOCs present to complete an accurate chemical profile of household and common product emissions not previously known. This instrument is one of the first of its kind and will serve as a key element in understanding the relationship between human physical and cognitive health and the built environment.</p>