Ventilation systems are closely connected to indoor environment. In industrial spaces it has a major impact due to air quality and thermal comfort requirements, which leads into health and economy improvements. Confluent jets ventilation system has been assess in Söderhamn Eriksson, a machinery company located in Mariannelund, Sweden, since it has been proved as the best ventilation performance. Moreover this system is worthy for both heating and cooling purposes, although just heating case will be developed in this thesis. By means of modelling software such as Gambit and Airpak, the company’s case could have been analyzed via Computational Fluid Dynamics (CFD) software, i.e. Fluent. The analyzed models were accepted after a thorough study of meshing parameters, bearing in mind computational limitations. Every temperature data gathered from simulation results has been verified with infrared camera figures taken at the company, thus contributing to reach reliable conclusions. As it is inferred from previous papers and empiric theory, the flow field observed is also justified. Then, thermal comfort and air quality analysis relies on consistent facts. It has been found that current ventilation at the company is slightly misadjusted, since supplied air’s temperature and velocity are slightly off point. Therefore, it is recommended to reduce these values to reach better working environment.

Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-04-07T13:52:52Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AnaliseComputacionalCampos.pdf: 8199135 bytes, checksum: 4e41ee450e20c1b754db24b43b82d5fa (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-06-16T13:18:05Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AnaliseComputacionalCampos.pdf: 8199135 bytes, checksum: 4e41ee450e20c1b754db24b43b82d5fa (MD5) / Made available in DSpace on 2014-06-16T13:18:05Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AnaliseComputacionalCampos.pdf: 8199135 bytes, checksum: 4e41ee450e20c1b754db24b43b82d5fa (MD5) Previous issue date: 2008 / A simulação numérica do escoamento de ar em ambientes internos é na atualidade o método mais apropriado para análise de conforto térmico em ambientes internos. O escoamento de ar nesses ambientes configura-se como um escoamento complexo, pois, em regra geral, é uma combinação de escoamentos cisalhantes livres (jatos) e cisalhantes de parede, além disso, esses escoamentos são governados por forças de inércia e forças de empuxo, caracterizando-o como de convecção mista. A combinação desses mecanismos cria um escoamento com características complexas, como zonas de recirculação, vórtices, descolamento e recolamento de camada-limite dentre outras. Portanto, a precisão da solução estará diretamente ligada, principalmente, na habilidade do modelo de turbulência adotado de reproduzir as características turbulentas do escoamento de ar e da transferência térmica. O objetivo principal do presente trabalho foi a simulação computacional do ambiente térmico interno do galpão que abriga os geradores e motores Wärtzilä da Usina Termelétrica Santana no estado do Amapá. A formulação matemática baseada na solução das equações gerais de conservação inclui uma análise dos principais modelos de turbulência aplicados ao escoamento de ar em ambientes internos, assim como os processos de transferência de calor associados. Na modelagem numérica o método de volumes finitos é usado na discretização das equações de conservação, através do código comercial Fluent-Airpak, que foi usado nas simulações computacionais para a análise dos campos de velocidade e temperatura do ar. A utilização correta do programa computacional foi testada e validada para o problema através da simulação precisa de casos retirados da literatura. Os resultados numéricos foram comparados a dados obtidos de medições experimentais realizados no galpão e apresentou boa concordância, considerando a complexidade do problema simulado, o objetivo da simulação em face da diminuição da temperatura no interior do galpão e, também, em função das limitações encontradas quando da tomada das medições experimentais. Além disso, foram feitas simulações de estratégias de melhoria do ambiente térmico da Usina, baseadas na realidade levantada e nos resultados da simulação numérica. Finalmente, foram realizadas simulações do protótipo de solução proposto para a diminuição da temperatura interna do galpão o que possibilitará um aumento, na faixa de 20 a 30%, do tempo de permanência no interior do galpão. / The numerical simulation of the airflow in internal environments is in the present time the most appropriate method for analysis of thermal comfort indoors. The airflow in these environments is configured as a complex one, therefore, in general, it is a combination of free-shear flow (jet) and of wall-shear flow, moreover, these are governed by inertia and buoyancy forces, characterizing a situation of mixing convection. The combination of these mechanisms creates an airflow with complex characteristics, as recirculation zones, vortices, detachment and re-attachment of boundary layer amongst others. Therefore, the precision of the solution will be directly connected, mainly, with the ability of the adopted turbulence model to reproduce the turbulent characteristics of the airflow and thermal transfers. The main objective of the present work was the computational simulation of the internal thermal environment of the enclosure which shelters the generators and the Wärtzilä engines of the thermo-electric power plant of Santana in the state of Amapá (Brazil). The mathematical formulation based on the solution of the general equations of conservation includes an analysis of the principal models of turbulence applied to the airflow inside the enclosure, as well as the heat transfer processes associated. The finite-volume numerical method is used in the discretization of the conservation equations, through the Fluent-Airpak software, for the analysis of the distribution of air velocity and temperature fields. The correct use of the software was tested and validated by successfully simulating problems solved by other authors. The numerical results of the airflow in the enclosure were compared with the experimental data and presented a good agreement, by considering the complexity of the simulated problem and the limitations and difficulties found during measurements. Moreover, simulations are presented of strategies for improvement of the thermal environment, based on the actual reality and on the results of the numerical simulations. Finally, simulations of a prototype solution are presented with the reduction of the internal temperature in the enclosure. This solution allows an increase of the exposure time inside the enclosure, from 20 up to 30%, and improves the thermal comfort of the thermo-electric power plant.