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Advisor(s)
Abstract(s)
Para a proteção de casas, prédios e estruturas metálicas, existem tanto proteções passivas (utilização de selantes para vedações, materiais retardantes de chamas, etc), quanto proteções ativas (Sprinklers, hidrantes e extintores). O foco deste trabalho é abordar as características térmicas dos materiais de proteção a incêndio e caraterizar as propriedades térmicas das placas de Silicato de Cálcio, material muito importante no papel em retardar a propagação de chamas e calor em construções.
Para isso, foram feitos estudos para entender quais são as principais variáveis que afetam a condução de calor no material e sua respectiva condutividade térmica efetiva. Para entender estes fenômenos, foi realizado o ensaio de secagem, conforme a ASTM C1498-01, para identificar o percentual de teor de água presente no material. Essa característica é importante, pois após o aquecimento do material, este tende a evaporar a água livre dentro do material e dar origem a porosidades, as quais vão afetar diretamente a condutividade térmica efetiva do material. Além disso, foi utilizado de um artigo de referência para determinar as demais reações que ocorrem com a elevação da temperatura no material, todas elas influenciando na porosidade e na liberação (ou absorção) de calor pela devida reação.
Foi realizado também o ensaio no calorímetro de cone, justamente para simular uma situação de incêndio, sendo este ensaio baseado na ISO 5660. Com isso, é possível obter principalmente o campo de temperaturas dentro do material (posicionando termopares em pontos estratégicos) e a perda de massa total. Levando em consideração a variação de massa específica, calor específico a pressão constante, condutividade térmica efetiva e porosidade, em função da temperatura e do tempo, pode-se então desenvolver um modelo numérico para o problema de condução de calor para finalmente obter-se as curvas de temperatura semelhantes as obtidas no método experimental.
Esse ajuste das curvas entre experimental e numérica foi realizada graças a utilização do algoritmo modificado de Levenberg-Marquadt, onde foi utilizado como variável de otimização a condutividade térmica do sólido, para consequentemente obter a condutividade térmica real do nosso estudo. A solução numérica, como será apresentado neste trabalho, apresentou resultados satisfatórios e com esse estudo como base, podemos utilizar das ideias de trabalhos futuros para refiná-lo e posteriormente aplicar para outros materiais de proteção a incêndio.
For the protection of houses, buildings and metallic structures, there are both passive protections (fences, flame retardant materials, etc), as well as active protections (Sprinklers, hydrants and extinguishers). The focus of this work is to address the thermal characteristics of fire protection materials and after that, characterize the thermal properties of Calcium Silicate plates, which is a very important material in retarding the spread of flames and heat in buildings. Studies were made to understand the main variables that affect the heat conduction in the material and hits effective thermal conductivity. In order to understand these phenomena, the drying tests were carrying out, according to ASTM C1498-01, to identify the percentage of water content present in the material. This characteristic is important, because after heating the material, it tends to evaporate the free water inside the material and start to produce porosities, which will directly affect the effective thermal conductivity of the material. In addition, a reference article was used to determine the other reactions that occur with the elevation of the temperature in the material, all of them influencing the porosity and the release (or absorption) of heat by the due reaction. The cone calorimeter test was also carried out, to simulate a fire situation based on ISO 5660. After doing this test, it was possible to obtain mainly the temperature field inside the material (placing thermocouples at discrete points) and the total mass loss. Taking into account the variation in specific mass, specific heat at constant pressure, effective thermal conductivity and porosity, as a function of temperature and time, a numerical model for the heat conduction problem could be developed to obtain temperature fields similar to those obtained in the experimental method. The adjustment of the curves between experimental and numerical results were performed with the modified Levenberg-Marquadt optimization algorithm. The thermal conductivity of the solid was used as an optimization variable, in order to obtain the material effective thermal conductivity. Our numerical solution, as it will be presented in this work, presented satisfactory results and can be applied for other fire protection materials.
For the protection of houses, buildings and metallic structures, there are both passive protections (fences, flame retardant materials, etc), as well as active protections (Sprinklers, hydrants and extinguishers). The focus of this work is to address the thermal characteristics of fire protection materials and after that, characterize the thermal properties of Calcium Silicate plates, which is a very important material in retarding the spread of flames and heat in buildings. Studies were made to understand the main variables that affect the heat conduction in the material and hits effective thermal conductivity. In order to understand these phenomena, the drying tests were carrying out, according to ASTM C1498-01, to identify the percentage of water content present in the material. This characteristic is important, because after heating the material, it tends to evaporate the free water inside the material and start to produce porosities, which will directly affect the effective thermal conductivity of the material. In addition, a reference article was used to determine the other reactions that occur with the elevation of the temperature in the material, all of them influencing the porosity and the release (or absorption) of heat by the due reaction. The cone calorimeter test was also carried out, to simulate a fire situation based on ISO 5660. After doing this test, it was possible to obtain mainly the temperature field inside the material (placing thermocouples at discrete points) and the total mass loss. Taking into account the variation in specific mass, specific heat at constant pressure, effective thermal conductivity and porosity, as a function of temperature and time, a numerical model for the heat conduction problem could be developed to obtain temperature fields similar to those obtained in the experimental method. The adjustment of the curves between experimental and numerical results were performed with the modified Levenberg-Marquadt optimization algorithm. The thermal conductivity of the solid was used as an optimization variable, in order to obtain the material effective thermal conductivity. Our numerical solution, as it will be presented in this work, presented satisfactory results and can be applied for other fire protection materials.
Description
Keywords
Materiais de proteção ao fogo Condutividade térmica Reação ao fogo Silicato de cálcio Incêndio