4 resultados para Escoamento multifásico - Métodos de simulação

em Repositório Institucional da Universidade Federal do Rio Grande do Norte


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This master thesis introduces assessment procedures of daylighting performance in office rooms with shaded opening, recommendations for Natal-RN (Latitude 05,47' S, Longitude 35,11' W). The studies assume the need of window exterior shading in hot and humid climate buildings. The daylighting performance analyses are based on simulated results for three levels of illuminance (300,500 e 1000 lux) between 08h00 e 16h00, in rooms with 2,80 m height, 6 m large and 4 m, 6 m e 8 m depths, with a centered single opening, window wall ratio (20%, 40% e 60%), four orientations (North, East, South and West), and two types of sky (clear and partially cloudy). The sky characteristics were statistically determined based on hourly data from INPE-CRN solar and daylighting weather station. The lighting performance is resulted from dynamic computer simulation of 72 models using Troplux 3.12. The simulation results were assessed using a new parameter to quantify the use of interior daylighting, the useful percentage of daylight (PULN), which corresponds to the time fraction with satisfactory light, in accordance with the illuminance design. The passive zone depths are defined based on the PULN. Despite the failures of illuminance data from the weather station, the analyses ratified the high potential of daylighting for shaded rooms. The most influential variables on the lighting performance are the opening size and the illuminance of design, while the orientation is a little influential

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Natural ventilation is an efficient bioclimatic strategy, one that provides thermal comfort, healthful and cooling to the edification. However, the disregard for quality environment, the uncertainties involved in the phenomenon and the popularization of artificial climate systems are held as an excuse for those who neglect the benefits of passive cooling. The unfamiliarity with the concept may be lessened if ventilation is observed in every step of the project, especially in the initial phase in which decisions bear a great impact in the construction process. The tools available in order to quantify the impact of projected decisions consist basically of the renovation rate calculations or computer simulations of fluids, commonly dubbed CFD, which stands for Computational Fluid Dynamics , both somewhat apart from the project s execution and unable to adapt for use in parametric studies. Thus, we chose to verify, through computer simulation, the representativeness of the results with a method of simplified air reconditioning rate calculation, as well as making it more compatible with the questions relevant to the first phases of the project s process. The case object consists of a model resulting from the recommendations of the Código de Obras de Natal/ RN, customized according to the NBR 15220. The study has shown the complexity in aggregating a CFD tool to the process and the need for a method capable of generating data at the compatible rate to the flow of ideas and are discarded during the project s development. At the end of our study, we discuss the necessary concessions for the realization of simulations, the applicability and the limitations of both the tools used and the method adopted, as well as the representativeness of the results obtained

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This Masters Degree dissertation seeks to make a comparative study of internal air temperature data, simulated through the thermal computer application DesignBuilder 1.2, and data registered in loco through HOBO® Temp Data Logger, in a Social Housing Prototype (HIS), located at the Central Campus of the Federal University of Rio Grande do Norte UFRN. The prototype was designed and built seeking strategies of thermal comfort recommended for the local climate where the study was carried out, and built with panels of cellular concrete by Construtora DoisA, a collaborator of research project REPESC Rede de Pesquisa em Eficiência Energética de Sistemas Construtivos (Research Network on Energy Efficiency of Construction Systems), an integral part of Habitare program. The methodology employed carefully examined the problem, reviewed the bibliography, analyzing the major aspects related to computer simulations for thermal performance of buildings, such as climate characterization of the region under study and users thermal comfort demands. The DesignBuilder 1.2 computer application was used as a simulation tool, and theoretical alterations were carried out in the prototype, then they were compared with the parameters of thermal comfort adopted, based on the area s current technical literature. Analyses of the comparative studies were performed through graphical outputs for a better understanding of air temperature amplitudes and thermal comfort conditions. The data used for the characterization of external air temperature were obtained from the Test Reference Year (TRY), defined for the study area (Natal-RN). Thus the author also performed comparative studies for TRY data registered in the years 2006, 2007 and 2008, at weather station Davis Precision Station, located at the Instituto Nacional de Pesquisas Espaciais INPE-CRN (National Institute of Space Research), in a neighboring area of UFRN s Central Campus. The conclusions observed from the comparative studies performed among computer simulations, and the local records obtained from the studied prototype, point out that the simulations performed in naturally ventilated buildings is quite a complex task, due to the applications limitations, mainly owed to the complexity of air flow phenomena, the influence of comfort conditions in the surrounding areas and climate records. Lastly, regarding the use of the application DesignBuilder 1.2 in the present study, one may conclude that it is a good tool for computer simulations. However, it needs some adjustments to improve reliability in its use. There is a need for continued research, considering the dedication of users to the prototype, as well as the thermal charges of the equipment, in order to check sensitivity

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The assessment of building thermal performance is often carried out using HVAC energy consumption data, when available, or thermal comfort variables measurements, for free-running buildings. Both types of data can be determined by monitoring or computer simulation. The assessment based on thermal comfort variables is the most complex because it depends on the determination of the thermal comfort zone. For these reasons, this master thesis explores methods of building thermal performance assessment using variables of thermal comfort simulated by DesignBuilder software. The main objective is to contribute to the development of methods to support architectural decisions during the design process, and energy and sustainable rating systems. The research method consists on selecting thermal comfort methods, modeling them in electronic sheets with output charts developed to optimize the analyses, which are used to assess the simulation results of low cost house configurations. The house models consist in a base case, which are already built, and changes in thermal transmittance, absorptance, and shading. The simulation results are assessed using each thermal comfort method, to identify the sensitivity of them. The final results show the limitations of the methods, the importance of a method that considers thermal radiance and wind speed, and the contribution of the chart proposed