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Abstract(s)
Apesar da segurança contra incêndios ser de uma grande relevância na proteção de bens
e pessoas, num parque de estacionamento, o sistema de desenfumagem apresenta uma
responsabilidade acrescida na desenfumagem dos gases de escape. Por essa razão, este,
tem de ser um sistema, além de eficaz, eficiente na promoção do escoamento orientado
às zona de extração.
No contexto deste trabalho foram identificados vários casos de ventilação em parques de
estacionamento que se encontravam aparentemente desadequados ao seu funcionamento
de forma eficiente. Para atingir esse objetivo desenvolvem-se várias simulações em CFD
com recurso ao programa livre FDS.
Muito do conhecimento usado no desenvolvimento das leis e de modelos de apoio
à regulação e compreensão dos fenómenos envolvidos num incêndio baseiam-se na
experiência acumulada ao longo dos anos. A lesgilação, em particular, carateriza a
necessidade dos equipamentos, mas não acrescenta sobra a melhor abordagem à sua
implementação deixando espaço para que surjam os problemas identificados como a
colocação de obstáculos no caminho dos ventiladores de impulso.
Tendo o exposto como motivação, neste trabalho reune-se, para um caso simplificado,
uma série de simulações onde se variam parâmetros que se consideram importantes na
categorização da melhor abordagem à colocação dos ventiladores de impulso, quando
confrontados com obstáculos no caminho do escoamento promovido pelos mesmos.
Dos resultados obtidos com as simulações desenvolveu-se um modelo de regressão
multivariada que permitisse apoiar na previsão da qualidade do ar e visibilidade que
permita a evacuação de pessoas em segurança. Finalmente, para verificar esse modelo
desenvolveu-se um novo caso, mais complexo, para comparar a previsão do modelo com a
sua aplicação a casos mais próximos da realidade. Este modelo mostrou-se ineficaz nessa
previsão apresentanto erros elevados. Uma das razões principais para as discrepâncias
encontradas está relacionada com a falta de dados usadas no desenvolvimento do modelo
já que a sua realização implicou dificuldades na verificação dos pressupostos necessárias
à sua validade.
In the context of this work, several cases of ventilation in parking lots that were inadequate to operate efficiently were identified. In this context, several CFD simulations were developed using the free FDS program. Although fire safety is of great importance in the protection of goods and people in a car park, the smoke control system has increased responsibility of exhausting fumes. For this reason, this has to be a system, efficient in promoting the flow directed to the extraction zone. Much of the knowledge used in the development of laws and models that support the regulation and understanding of phenomena is based on the experience accumulated over the years. The legislation, in particular, characterizes the needs for the equipment but does not add the best approach to its implementation, leaving room for the problems identified as the placement of obstacles in the way of the impulse fans. For a simplified case, this work presents a series of simulations with different parameters which were considered relevant in the categorization of the best approach to the placement of the impulse ventilators, when confronted with obstacles in the path of the flow promoted by them. From the results obtained with the simulations, a multivariate regression model was developed to support the prediction of air quality and visibility that allows the evacuation of people in safety. Finally, to verify this model, a new, more complex case was developed to compare the prediction of the model with its application to cases closer to reality. This model proved to be ineffective in this prediction with high errors. One of the main reasons for the discrepancies found is related to the lack of data used in the development of the model since its implementation implied difficulties in verifying the assumptions necessary to its validity.
In the context of this work, several cases of ventilation in parking lots that were inadequate to operate efficiently were identified. In this context, several CFD simulations were developed using the free FDS program. Although fire safety is of great importance in the protection of goods and people in a car park, the smoke control system has increased responsibility of exhausting fumes. For this reason, this has to be a system, efficient in promoting the flow directed to the extraction zone. Much of the knowledge used in the development of laws and models that support the regulation and understanding of phenomena is based on the experience accumulated over the years. The legislation, in particular, characterizes the needs for the equipment but does not add the best approach to its implementation, leaving room for the problems identified as the placement of obstacles in the way of the impulse fans. For a simplified case, this work presents a series of simulations with different parameters which were considered relevant in the categorization of the best approach to the placement of the impulse ventilators, when confronted with obstacles in the path of the flow promoted by them. From the results obtained with the simulations, a multivariate regression model was developed to support the prediction of air quality and visibility that allows the evacuation of people in safety. Finally, to verify this model, a new, more complex case was developed to compare the prediction of the model with its application to cases closer to reality. This model proved to be ineffective in this prediction with high errors. One of the main reasons for the discrepancies found is related to the lack of data used in the development of the model since its implementation implied difficulties in verifying the assumptions necessary to its validity.
Description
Trabalho final de mestrado para obtenção do grau de mestre em Engenharia Mecânica
Keywords
Incêdio Fire Segurança Safety Simulação Simulation Modelação Modeling CFD
Citation
COSTA, Sérgio Manuel Cavaleiro de Almeida - Análise de um sistema de desenfumagem para a atenuação do risco de incêndio. Lisboa: Instituto Superior de Engenharia de Lisboa, 2018. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa