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Previous issue date: 2005-12-16 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In the last decades there was a significant increasing of the numbers of researchers that joint efforts to find alternatives to improve the development of low environmental impact technology. Materials based on renewable resources have enormous potentials of applications and are seen as alternatives for the sustainable development. Within other parameters, the sustainability depends on the energetic efficiency, which depends on the thermal insulation. Alternative materials, including vegetal fibers, can be applied to thermal insulation, where its first goal is to minimize the loss of energy. In the present research, it was experimentally analyzed the thermal behavior of fiber blankets of sisal (Agave sisalana) with and without surface treatment with oxide hidroxide (NaOH). Blankets with two densities (1100/1200 and 1300/1400 g/m2) were submitted to three rates of heat transfer (22.5 W, 40 W and 62.5 W). The analysis of the results allowed comparing the blankets treated and untreated in each situation. Others experiments were carried out to obtain the thermal conductivity (k), heat capacity (C) and the thermal diffusivity (α) of the blankets. Thermo gravimetric analyses were made to the verification of the thermal stability. Based on the results it was possible to relate qualitatively the effect of the heat transfer through the sisal blankets subjected to three heat transfer rates, corresponding to three temperature values (77 ?C, 112 ?C e 155 ?C). To the first and second values of temperature it was verified a considerable reduction on the rate of heat transfer; nevertheless, to the third value of temperature, the surface of the blankets (treated and untreated) in contact with the heated surface of the tube were carbonized. It was also verified, through the analyses of the results of the measurements of k, C e α, that the blankets treated and untreated have values near to the conventional isolating materials, as glass wool and rock wool. It could be concluded that is technically possible the use of sisal blankets as constitutive material of thermal isolation systems in applications where the temperature do not reach values greater than 112 ?C / Nas ?ltimas d?cadas, t?m sido grandes os esfor?os dos pesquisadores na busca por alternativas sustent?veis e conhecimentos sobre como se poder? continuar promovendo o desenvolvimento sem que isso ocorra de forma agressiva ao ambiente. Materiais oriundos de fontes renov?veis possuem grande potencial de aplicabilidade e s?o vistos como alternativas para um desenvolvimento sustent?vel. Dentre outros par?metros, a sustentabilidade depende da efici?ncia energ?tica e essa, por sua vez, depende de isolantes t?rmicos. Materiais alternativos, entre eles as fibras vegetais, podem ser aplicadas para fins de isolamento t?rmico, cujo principal objetivo ? minimizar as perdas de energia. Na presente pesquisa, analisou-se experimentalmente a aplicabilidade de mantas de fibras de sisal (Agave sisalana), in natura e com tratamento superficial com hidr?xido de s?dio (NaOH), ? isola??o t?rmica. Foram utilizadas mantas de duas gramaturas (1100/1200 e 1300/1400 g/m2) submetidas a tr?s taxas de transfer?ncia de calor (22,5 W, 40 W e 62,5 W). A an?lise dos resultados obtidos permitiu comparar a capacidade de isola??o das mantas tratada e in natura em cada situa??o. Ensaios foram realizados para determina??o da condutividade t?rmica (k), capacidade calor?fica (C) e a difusividade t?rmica (α) das mantas; a estabilidade t?rmica foi verificada por meio de an?lise termogravim?trica (TGA). Com base nos resultados, foi poss?vel relacionar qualitativamente o efeito da transfer?ncia de calor atrav?s das mantas de sisal submetidas a tr?s condi??es de aquecimento, correspondentes a tr?s valores de temperatura (77 ?C, 112 ?C e 155 ?C). Nas duas condi??es iniciais, verificou-se que as mantas de sisal proporcionaram uma significativa redu??o da taxa de transfer?ncia de calor. Na terceira condi??o (155 ?C), contudo, as superf?cies das mantas (tratadas e in natura) em contato com a superf?cie aquecida do tubo ficaram carbonizadas. Por meio das an?lises dos resultados das medi??es de k, C e α, constatou-se que as mantas tratadas e in natura apresentaram valores bem pr?ximos aos de materiais isolantes comerciais (l? de vidro e l? de rocha). P?de-se concluir que mantas de sisal podem ser empregadas como material constituinte de sistemas de isola??o t?rmica para aplica??es em que a temperatura n?o ultrapasse 112 ?C
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15545 |
| Date | 16 December 2005 |
| Creators | Neira, Dorivalda Santos Medeiros |
| Contributors | CPF:35846852491, http://lattes.cnpq.br/0490476694313938, Hildebrand J?nior, Le?nidas, CPF:09890962896, http://lattes.cnpq.br/9093463713286889, Duarte, Raimundo Nonato Calazans, CPF:70178941468, http://lattes.cnpq.br/6888984510203323, Marinho, George dos Santos |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Mec?nica, UFRN, BR, Tecnologia de Materiais; Projetos Mec?nicos; Termoci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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