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Abstract(s)
Os sistemas de aquecimento, ventilação e ar condicionado (AVAC) apresentam um
dos maiores consumos de energia no setor dos edifícios. Para atingir a meta de
descarbonização imposta pela União Europeia, diversas técnicas têm sido utiliza das para reduzir os custos energéticos destes sistemas, preservando as suas funções.
Uma forma de reduzir o consumo de energia destes sistemas passa por aperfeiçoar
a ventilação dos espaços interiores. O uso da mecânica de fluidos computacional
(CFD) para estudar estratégias de ventilação em espaços interiores tem sido uma
ferramenta crescente, no entanto, a precisão dos resultados obtidos depende muito
da implementação adequada dos modelos e das condições necessárias.
Nesta dissertação, uma nova abordagem de ventilação, a ventilação instacionária,
vai ser estudada por meio da mecânica de fluidos computacional, usado o software
OpenFOAM para o efeito.
Neste trabalho, foram primeiramente validadas as técnicas numéricas, de discre tização e de modelação física de CFD baseando-nos em dois benchmarks experi mentais disponíveis na literatura. Num primeiro caso, caso isotérmico, simulações
URaNS (Unsteady Reynolds-Averaged Navier-Stokes) realizadas com o algoritmo
pimpleFoam foram estudadas para os modelos de turbulência de altos números de
Reynolds k − e RNG k − e baixos números de Reynolds LaunderSharma k −
e k − ωSST. Num segundo caso, caso não isotérmico, simulações URaNS foram
realizadas usado o algoritmo buoyantPimpleFoam apenas para os modelos de alto
número de Reynolds k− com presença do termo de produção térmica e dos modelos
k − e RNG k − sem este termo.
Por fim, foi simulada a sala de testes de equipamentos de climatização (SATEC) do
Instituto Superior de Engenharia do Porto (ISEP), de forma a validar os resultados
numéricos com os resultados experimentais. Em seguida, foi testada computacional mente a estratégia de ventilação instacionária, implementada a partir de um caudal
periódico de sinal sinusoidal, onde vários caudais médios, frequências e amplitudes
dos sinais foram estudados.
Heating, ventilation and air conditioning (HVAC) systems have one of the highest energy consumptions in the building sector. In order to reach the decarbonization target imposed by the European Union, several techniques have been used to reduce the energy costs of these systems, preserving their functions. One way to reduce the energy consumption of these systems is to improve the ventilation of internal spaces. The use of computational fluid dynamics (CFD) to study ventilation strategies in indoor spaces has been a growing tool, however, the accuracy of the obtained re sults is very reliant on the appropriate implementation of the models and necessary conditions. In this dissertation, a new approach to ventilation, unsteady ventilation, will be studied through computational fluid dynamics, using the OpenFOAM software. In this work, numerical, discretization and physical CFD modeling techniques were first validated based on two experimental benchmarks available in the literature. In a first case, isothermal case, URaNS (Unsteady Reynolds-Averaged Navier-Stokes) simulations carried out with the pimpleFoam algorithm were studied for high Rey nolds numbers turbulence models k − and RNG k − and low Reynolds numbers LaunderSharma k− and k−ωSST. In a second case, non-isothermal case, URaNS simulations were performed using the buoyantPimpleFoam algorithm only for the high Reynolds numbers models k − with buoyant production term and the models k − and RNG k − without this term. Finally, the HVAC equipment test room (SATEC) of Instituto Superior de Enge nharia do Porto (ISEP) was simulated, in order to validate the numerical results with the experimental ones. Then, the unsteady ventilation strategy was compu tationally tested, by implementing a periodic sinusoidal signal flow, where various average flow rates, frequencies and amplitudes of the signals were studied.
Heating, ventilation and air conditioning (HVAC) systems have one of the highest energy consumptions in the building sector. In order to reach the decarbonization target imposed by the European Union, several techniques have been used to reduce the energy costs of these systems, preserving their functions. One way to reduce the energy consumption of these systems is to improve the ventilation of internal spaces. The use of computational fluid dynamics (CFD) to study ventilation strategies in indoor spaces has been a growing tool, however, the accuracy of the obtained re sults is very reliant on the appropriate implementation of the models and necessary conditions. In this dissertation, a new approach to ventilation, unsteady ventilation, will be studied through computational fluid dynamics, using the OpenFOAM software. In this work, numerical, discretization and physical CFD modeling techniques were first validated based on two experimental benchmarks available in the literature. In a first case, isothermal case, URaNS (Unsteady Reynolds-Averaged Navier-Stokes) simulations carried out with the pimpleFoam algorithm were studied for high Rey nolds numbers turbulence models k − and RNG k − and low Reynolds numbers LaunderSharma k− and k−ωSST. In a second case, non-isothermal case, URaNS simulations were performed using the buoyantPimpleFoam algorithm only for the high Reynolds numbers models k − with buoyant production term and the models k − and RNG k − without this term. Finally, the HVAC equipment test room (SATEC) of Instituto Superior de Enge nharia do Porto (ISEP) was simulated, in order to validate the numerical results with the experimental ones. Then, the unsteady ventilation strategy was compu tationally tested, by implementing a periodic sinusoidal signal flow, where various average flow rates, frequencies and amplitudes of the signals were studied.
Description
Keywords
Ventilation strategies Computational fluid dynamics OpenFOAM URaNS Turbulence models Unsteady ventilation