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Simulação Numérica de Chamas de Biogás Enriquecido com Hidrogénio
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As alterações climáticas têm acelerado o interesse e investimento em fontes de energia
renováveis. É neste contexto que surge esta dissertação, onde se simulam numericamente
chamas de biogás enriquecido com hidrogénio. O biogás e o hidrogénio são recursos que
se espera virem a ter uma relevância significativa no paradigma energético, e cujas caracte-
rísticas não favorecem as suas utilizações em estado puro e que parecem complementares.
Tendo isto, neste trabalho abordam-se tópicos que pretendem motivar e adquirir
conhecimentos sobre o tema. De seguida realizou-se um estudo isotérmico baseado em
parâmetros relacionados com os pontos notáveis do escoamento, onde se conclui que a
independência dos resultados é obtida a partir dos cerca de 1,4 milhões de elementos.
Finalmente, efetuaram-se três estudos com combustão que investigam as alterações
na chama ao adicionar dióxido de carbono ao metano (simular biogás), ao diminuir a
temperatura de entrada do ar e ao alterar a razão de equivalência. Nestes estudos procurou-
se ainda perceber se a adição de 25% de hidrogénio, sem alterar a potência injetada de 10kW,
melhora significativamente as características da combustão ou não, tendo-se concluído
que a mesma provoca um aumento da eficiência da combustão permitindo uma queima
mais completa do combustível.
Recent climate changes have increased interest and investment in renewable energy sources. It is in this context that this dissertation is presented, in which biogas enriched with hydrogen flames are numerically simulated. Biogas and hydrogen are resources whose relevance and importance are expected to increase significantly in the near future, and whose characteristics don’t favor their use in a pure state and which seem to be complementary. In this sense, this work begins with topics that intend to motivate and acquire knowl- edge about the subject. Next, an isothermal study based on parameters related with the flow notable points was carried out, concluding that the independence of the results is achieved from approximately 1.4 million elements. Finally, three chemical reaction studies were carried out to see if there were any major changes in the flame produced when carbon dioxide was added to methane (simulate biogas), when the air inlet temperature was lowered and when the equivalence ratio was changed. These studies also sought to understand whether the addition of 25% hydrogen to biogas significantly improves the combustion characteristics and concluded that it increases the combustion efficiency, allowing a more complete combustion of the fuel.
Recent climate changes have increased interest and investment in renewable energy sources. It is in this context that this dissertation is presented, in which biogas enriched with hydrogen flames are numerically simulated. Biogas and hydrogen are resources whose relevance and importance are expected to increase significantly in the near future, and whose characteristics don’t favor their use in a pure state and which seem to be complementary. In this sense, this work begins with topics that intend to motivate and acquire knowl- edge about the subject. Next, an isothermal study based on parameters related with the flow notable points was carried out, concluding that the independence of the results is achieved from approximately 1.4 million elements. Finally, three chemical reaction studies were carried out to see if there were any major changes in the flame produced when carbon dioxide was added to methane (simulate biogas), when the air inlet temperature was lowered and when the equivalence ratio was changed. These studies also sought to understand whether the addition of 25% hydrogen to biogas significantly improves the combustion characteristics and concluded that it increases the combustion efficiency, allowing a more complete combustion of the fuel.
Descrição
Palavras-chave
Biogás hidrogénio queimador combustão simulação numérica