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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

[pt] ESTUDO DA PIRÓLISE LENTA DA MADEIRA RECICLADA E AVALIAÇÃO DO EFEITO OXIDANTE DE NANOPARTÍCULAS DE FE2COO4 E CO3O4 / [en] STUDY OF THE THERMAL BEHAVIOR OF RECYCLED WOOD UNDER SLOW PYROLYSIS AND EVALUATION OF THE OXIDATIVE EFFECT OF FE2COO4 AND CO3O4 NANOPARTICLES

ANA CAROLINA MARQUES DOURADO 25 October 2019 (has links)
[pt] A demanda energética mundial está em constante crescimento e tal cenário faz aumentar a preocupação com os impactos ambientais, muitos deles decorrentes da exploração de combustíveis fósseis e sua utilização desmedida. Neste contexto, o estudo da pirólise da biomassa apresenta uma alternativa para a produção direta de calor que pode vir a ser utilizado em usinas termoelétricas sustentáveis. Uma investigação foi realizada abordando o tema da reciclagem de madeira sobre a possibilidade de aproveitá-la a biomassa principal deste processo. Este trabalho apresenta a caracterização da madeira reciclada bem como da madeira de eucalipto para poder averiguar a similaridade química entre as duas biomassas. Para tanto foram realizadas análises de espectroscopia de infravermelhos (FTIR) e difração de raios-X (DRX), além de análises de microscopia eletrônica de varredura com espectroscopia por dispersão de energia (MEV/EDS). Com o auxílio da técnica de termogravimetria (TG) foram realizados experimentos de pirólise lenta da madeira reciclada, a partir dos quais foram identificados eventos térmicos, caracterizados por perdas de massa. Para verificar um possível efeito oxidante dos óxidos Fe2CoO4 e Co3O4, realizou-se também pirólise lenta da mistura da madeira reciclada com cada um dos óxidos, tendo sido identificados eventos térmicos que não estavam presentes nos experimentos com a madeira pura. Os principais eventos foram avaliados cineticamente por métodos model-free que permitem a determinação da energia de ativação sem a necessidade de assumir uma ordem de reação. Foram utilizados os métodos de Kissinger (KS) e Kissinger-Akahira-Sunose (KAS), empregando os dados de experimentos realizados no TG com cinco taxas de aquecimento diferentes até 1100 graus Celsius. Para o evento térmico de maior importância, entre 200 e 390 graus Celsius tanto na madeira pura quanto na mistura, o ajuste de ambos o métodos foi satisfatório e está de acordo com a literatura. / [en] World s energy demand is constantly growing, and this scenario raises the concern about environmental impacts, many of them resulting from the constant manipulation of fossil fuels and their excessive use. In this context, the study of biomass pyrolysis presents an alternative for the direct production of heat that can be used in sustainable thermoeletric plants. To this end, a research has been carried out on the possibility of taking advantage of recycled wood as the main biomass of this process, an investigation that has been carried out along with a company in the field of wood recycling. This work presents the characterization of a recylced and a typical Brazilian eucalyptus wood with the purpose of proving their chemical similarity. Therefore, analysis of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) was performed. Thermogravimetric (TG) experiments were carried out with slow pyrolysis of recycled wood and eucalyptus wood, from wich were identified thermal events, characterized by mass losses. To verify a possible oxidative effect of the compounds Fe2CoO4 and Co3O4, slow pyrolysis of a mixture of the recycled wood with each of the oxides was also performed, and thermal events that were not present in the experiments with the pure wood were identified. The main thermal events were kinetic investigated with model-free methods wich allows the determination of the activation energy without the need of a reaction order pre-stipulated. In this workk were tested the Kissinger (KS) and Kissinger-Akahira-Sunose (KAS) model-free methods and the TG data of five different heating rate were collected until 1100 Celsius degrees. For the most relevant thermal event, wich occurs from 200 to 390 Celsius degrees (for recycled wood and its mixture with the oxides) the adjustment of both methods was fine and accordance with literature.
2

Prefabricerat fasadsystem med återanvänt trä : en undersökning med FEM modelleringar och varierande materialparametrar / Prefabricated facade system with recycled wood : an investigation with FEM modeling and varying material parameters

Almestrand, Lovisa January 2024 (has links)
Sammanfattning Denna studie undersöker möjligheten att använda återanvänt trä från rivningsvirke i prefabricerade fasadsystem, med fokus på att minska bygg- och fastighetssektorns koldioxidutsläpp. Syftet är att med hjälp av finita elementmetoden (FEM) modellera och dimensionera fasadelement som kan användas i FÅTT-projektet och Arctic Center of Energy (ACE) i Skellefteå. Studien jämför mekaniska egenskaper mellan gammalt och nyproducerat trä samt undersöker hur fuktinducerade rörelser påverkar fasadelementen. Studiens resultat visade på att Fasadelement 1 med dimension 70x195 mm i ramen alternativt Fasadelement 3 med 45x145 i ramen var bäst lämpade för projektet. Resultaten från litteraturstudien visar att återanvänt trä kan uppfylla de nödvändiga kraven för hållbarhet och formstabilitet, vilket innebär att det finns stor potential för industriell produktion av fasadelement med återbrukat virke. Denna studie bidrar med underlag och kunskap för framtida utveckling och användning av hållbara byggmaterial inom byggindustrin. / Abstract This study investigates the potential of using reclaimed wood from demolition waste in prefabricated facade systems, aiming to reduce carbon emissions in the construction and real estate sector. The purpose is to model and design facade elements using the Finite Element Method (FEM) for the FÅTT-project and the Arctic Center of Energy (ACE) in Skellefteå. The study compares the mechanical properties of old and newly produced wood and examines how moisture-induced movements affect the facade elements. The results of the study showed that Facade Element 1 with dimensions 70x195 mm in the frame or alternatively Facade Element 3 with 45x145 mm in the frame were best suited for the project. The findings from the literature review show that reclaimed wood can meet the necessary requirements for durability and dimensional stability, indicating significant potential for industrial production of facade elements using recycled wood. This study provides insights and a solid foundation for future development and use of sustainable building materials within the construction industry.

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