Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-08-09T11:35:59Z No. of bitstreams: 1 Nilmar Luís Arenhardt_.pdf: 2851510 bytes, checksum: bd406be47f89d12c8e8db0289ab9dbb8 (MD5) / Made available in DSpace on 2017-08-09T11:36:00Z (GMT). No. of bitstreams: 1 Nilmar Luís Arenhardt_.pdf: 2851510 bytes, checksum: bd406be47f89d12c8e8db0289ab9dbb8 (MD5) Previous issue date: 2017-05-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apesar de muitas vezes as condições climáticas serem favoráveis para alcançar o conforto térmico em edificações que operam com o uso da ventilação natural, o número de edifícios que recorrem ao resfriamento mecânico, por exemplo aos condicionadores de ar, como principal estratégia de climatização tem aumentado consideravelmente. Além de problemas devido ao elevado consumo de energia, alguns estudos apontam que essa situação pode proporcionar uma má qualidade do ar interior, o que para o caso de ambientes de ensino pode ser gravemente prejudicial. Em contrapartida, o uso da ventilação mecânica pode gerar um efeito significativo no resfriamento interno com um consumo inferior de energia e com melhores taxas de renovação de ar. Sendo assim, este trabalho tem como objetivo principal analisar a influência da renovação de ar no conforto térmico de estudantes universitários, comparando resultados de medições de campo e de pesquisas subjetivas em salas de aula com ventilação natural e uma sala com sistema de ventilação mecânica. Os experimentos de campo foram realizados em salas do campus da Universidade do Vale do Rio dos Sinos (Unisinos) em São Leopoldo-RS, com ênfase na estação mais quente do ano. Os dados foram coletados a partir de medições ambientais realizadas concomitantemente às pesquisas subjetivas, que foram realizadas por meio de um questionário entregue aos estudantes, ocupantes dos ambientes avaliados, resultando em um total de 616 questionários. As análises foram realizadas a partir das informações obtidas, sendo os resultados apresentados em forma de gráficos e tabelas, através do cruzamento entre os dados microclimáticos e as respostas dos usuários. Os resultados mostraram que a sensação térmica dos ocupantes da sala com sistema de ventilação mecânica foi mais satisfatória quando comparados aos usuários das demais salas avaliadas. Em relação a aceitabilidade térmica nos dias de avaliação comparativa, 72,5% dos ocupantes da sala com maior renovação de ar classificaram o ambiente como “aceitável” e 27,5% como “inaceitável”. Nas demais salas apenas 40% dos ocupantes classificaram o ambiente como “aceitável” e 60% como “inaceitável”. O estudo também mostrou, para os meses da estação mais quente, uma melhor aplicabilidade do modelo de conforto adaptativo na sala de aula com índices mais elevados de vazão de ar externo. Os resultados encontrados evidenciam ainda que o aumento da taxa de renovação de ar na sala de aula proposta, em conjunto com as ações adaptativas dos ocupantes, proporcionou melhores condições de conforto térmico quando comparada às salas com ventilação natural. / Although many times the climate conditions are appropriate to achieve thermal comfort in buildings that operate with natural ventilation, the number of buildings that apply mechanical cooling, for example the air conditioning, as main climatization strategy have increased considerably. Besides problems in consequence to the elevated energy consumption, some studies show that this situation can provide a bad indoor air quality (IAQ), which in case of teaching environments can be seriously harmful. On the other hand, the use of mechanical ventilation can generate a significant effect at inside cooling with lower energy consumption and with better air renewal rate. Therefore, this study aims to analyze the influence of air renewal at university students’ thermal comfort, comparing results of field measurements and subjective searches in classrooms with natural ventilation and a classroom with mechanical ventilation system. The field experiments were carried out in classrooms on the campus of the Universidade do Vale do Rio dos Sinos (Unisinos) in São Leopoldo city, with emphasis at the warmest season of the year. The data were collected from environmental measurements carried out concomitantly with subjective surveys, which were performed through a questionnaire delivered to the students, occupants of the evaluated environments, resulting in a total of 616 questionnaires. The analysis was carried out from the obtained information, and the results presented in the form of graphs and tables, through the crossing between the microclimatic data and the users' answers. The results showed that the classroom occupants with mechanical ventilation presented more satisfactory thermal sensation, comparing to users of other evaluated classrooms. In relation to thermal acceptability in comparative days evaluated, 72.5% of the occupants in classroom with greater air renewal classified the environment as "acceptable" and 27.5% as “unacceptable”. For the other classrooms, only 40% of the occupants classified the environment as "acceptable" and 60% as "unacceptable". The study also showed, at the months in warmest season, a better applicability of the adaptive comfort model in the classroom with higher rates of external airflow. The results also show that the increase of the air renewal rate in the proposed classroom, together with the adaptive actions of the occupants, provided better conditions of thermal comfort when compared to the rooms with natural ventilation.

Human performance and health are one of the most relevant topics in modern society. Especially at young ages, when academic performance is indispensable. Thus, as the human being spends most of its lifetime inside a building, thermal comfort has become an essential aspect of a room. The aim of the present research is to measure and evaluate the main thermal comfort parameters such as CO2 levels, relative humidity and indoor temperature so the variation in them can be seen in the study rooms of the library of the University of Gävle as there is student use. For it, Rotroninc Measurement Solutions CL11 sensors and a Testo hot wire probe sensor have been used, as well as IDA ICE software simulations for the result validation. From the research, has been seen that even though the VAV air renewal system works as it should, the CO2 level rises up to 1000 ppm, which is not recommended by different thermal comfort ruling institutions. This way, a modification to the ventilation system control is recommended, changing it from temperature control to CO2 level and temperature control. Moreover, it is seen that during the non-opening hours of the library the ventilation systems are disconnected, generating an important energy-saving without altering the thermal comfort of the rooms at the beginning of the day.

La préservation de la chaîne du froid est un paramètre particulièrement important dans le cadre de la distribution urbaine, où les fréquentes ouvertures de portes induisent une charge thermique d’infiltration. Afin de réduire les transferts de masse et de chaleur et de protéger l’ouverture, des rideaux d’air ont récemment été installés au niveau de l’ouverture des camions frigorifiques. L’objet de la présente étude est d’étudier ce type confinement. Deux modèles CFD ont été développés pour simuler les champs de températures et de vitesses dans un camion réfrigéré clos. Ils ont permis de montrer que la variation de la vitesse de soufflage ne modifie pas de manière significative la structure des écoulements. Différents conduits d’air sont modélisés. Les résultats numériques montrent que la configuration avec un conduit ouvert améliore fortement le renouvellement d’air. Puis, une étude numérique est réalisée dans le but d’étudier les infiltrations de chaleur et de masse au cours de l’ouverture des portes. Ces écoulements sont bien prédits par le modèle CFD, excepté à la transition entre les deux régimes d’infiltration. Une caisse expérimentale a été équipée d’un dispositif de rideau d’air composé d’un jet ambiant, d’un jet froid ou d’un jet double. En parallèle, un modèle numérique CFD a été développé pour étudier l’influence de différents paramètres. Une bonne concordance entre les résultats numériques et expérimentaux a été observée. L’efficacité du rideau d’air ambiant est maximale lorsque le point d’impact du rideau se situe dans le plan de l’ouverture. Le rideau double maintient efficacement l’homogénéité de la température pour de courtes ouvertures. Le rideau d’air froid est la meilleur configuration, il limite fortement l’augmentation de température de l’enceinte et permet des gains énergétiques importants. / Cold chain safety is a key parameter for urban distribution where the frequent door-opening induces a heat infiltration. In order to reduce heat and mass transfer, air curtain have recently been installed to protect the doorway of refrigerated truck. The aim of this work is to study this type of door insulation. Two CFD numerical models were developed to simulate the temperature and velocity fields in a closed refrigerated truck. These models showed that modifying the blowing velocity does not modify the air flow structure inside the cavity. Different air chutes were modelled. Numerical results demonstrate that the configuration with a convergent and an open duct strongly improves the air renewal. A numerical investigation was performed in order to study heat and mass infiltration rates during the opening. The infiltration flow rate is well predicted by the CFD model, except at the transition between both flow regimes. An experimental truck was equipped with an air curtain setup, composed by an ambient air jet, a cold air jet or a double jet. In parallel, a numerical CFD model was developed to study the influence of various parameters. Experimental and numerical results were found to be in good agreement. The maximum efficiency of the ambient air curtain is reached when the impact point of the jet occurs in the door plane at the ground level. This configuration is only relevant for short opening times. The double air curtain efficiently maintains the temperature homogeneity for short openings. The cold air curtain is the best configuration which strongly limits the temperature increase during the opening and allows important energy savings.