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District heating systems: case study development using modelica
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Sistemas de aquecimento de distritos são actualmente considerados uma solução viável para atingir as metas de emissões de CO2 na Europa, devido à sua capacidade de recuperar calor que seria desperdiçado e à sua compatibilidade com fontes de energia renovável.
Para dimensionar estes sistemas, programas de simulação de energia em edifícios são frequentemente usados, uma vez que possibilitam uma análise prática, em termos de tempo, das necessidades de consumo do distrito. No entanto, os programas convencionais foram inicialmente desenvolvidos para endereçar edifícios a uma escala individual, o que leva a uma necessidade de desenvolvimento de programas de nova geração que permitam a integração de sistemas de maior escala. Para este efeito, o anexo 60 da agência internacional do ambiente (AIA) visa o desenvolvimento de novas ferramentas computacionais para sistemas de edifícios e comunidades em Modelica, uma linguagem que permite a modelação de processos físicos extensos, complexos e de multi-domínio.
Esta dissertação está inserida na Actividade 2.2 do Anexo 60 e avalia diferentes formas de endereçar as necessidades de aquecimento e arrefecimento, utilizando como caso de estudo um bairro com 24 edifícios. A implementação em Modelica é detalhadamente descrita e uma analise de sensibilidade foi conduzida relativamente a quatro parâmetros que influenciam as necessidades anuais: Número de zonas térmicas consideradas, ganhos internos, temperatura do solo e trocas de calor entre edifícios adjacentes.
Concluiu-se que as necessidades de calor são particularmente sensíveis à forma como dividimos o interior dos edifícios e às trocas de calor entre os mesmos, enquanto as necessidades de arrefecimento revelaram maior sensibilidade à forma como são modelados os ganhos internos. Finalmente, o uso do Modelica para estas aplicações foi também avaliado.
As countries in Europe are focusing in reducing their CO2 emission levels, district heating systems (DHS) are considered to be a feasible solution due to their ability to re-use heat that would otherwise be wasted and their compatibility with renewable energy sources (RES). When sizing these systems, building energy simulation (BES) programs are often used as they allow a time-practical analysis of the district’s consumption needs. However, conventional BES programs were primarily designed to address buildings at an individual scale; hence the need for next-generation programs which can integrate larger scale building systems is clearly recognized. For this matter, Annex 60 (IEA EBC) is developing new computational tools for building and community energy systems using Modelica, an object-oriented modelling language for large, complex and multi-domain physical processes. This project is inserted in subtask 2.2 of Annex 60 and evaluates different ways to approach the heating and cooling needs of a neighbourhood case study. The implementation in Modelica is described in this dissertation and a sensitivity analysis was carried out regarding different levels of detail applied in four different fields that influence the annual demand: Number of thermal zones considered, internal gains, ground temperature and the heat transfer between adjacent buildings. It was concluded that the heat demand was more sensitive to the sub-zoning of the living space and the heat exchange between the buildings, while the cooling demand proved to be more sensitive to the way the internal gains are modelled. Ultimately, the use of Modelica for this application was also evaluated.
As countries in Europe are focusing in reducing their CO2 emission levels, district heating systems (DHS) are considered to be a feasible solution due to their ability to re-use heat that would otherwise be wasted and their compatibility with renewable energy sources (RES). When sizing these systems, building energy simulation (BES) programs are often used as they allow a time-practical analysis of the district’s consumption needs. However, conventional BES programs were primarily designed to address buildings at an individual scale; hence the need for next-generation programs which can integrate larger scale building systems is clearly recognized. For this matter, Annex 60 (IEA EBC) is developing new computational tools for building and community energy systems using Modelica, an object-oriented modelling language for large, complex and multi-domain physical processes. This project is inserted in subtask 2.2 of Annex 60 and evaluates different ways to approach the heating and cooling needs of a neighbourhood case study. The implementation in Modelica is described in this dissertation and a sensitivity analysis was carried out regarding different levels of detail applied in four different fields that influence the annual demand: Number of thermal zones considered, internal gains, ground temperature and the heat transfer between adjacent buildings. It was concluded that the heat demand was more sensitive to the sub-zoning of the living space and the heat exchange between the buildings, while the cooling demand proved to be more sensitive to the way the internal gains are modelled. Ultimately, the use of Modelica for this application was also evaluated.
Descrição
Tese de mestrado integrado em Engenharia da Energia e do Ambiente , apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2015
Palavras-chave
Necessidades de aquecimento e arrefecimento de um distrito Simulação de edifícios Modelica/Dymola Anexo 60 Teses de mestrado - 2015