Aluminium titanium oxynitrides were studied as candidate materials for high temperature absorbers in solar selective coatings due to their excellent stability and their tuneable optical behaviour. A set of individual AlyTi1-y(OxN1-x) layers with different oxygen content was prepared by cathodic vacuum arc (CVA) deposition. The composition, morphology, phase structure and microstructure of the films were characterized by elastic recoil detection (ERD), scanning and transmission electron microscopy and X-ray diffraction. An fcc phase structure is found in a broad compositional range of AlyTi1-y(OxN1-x). Simultaneously, sample microstructure and morphology undergo systematic changes from a columnar growth to the development of a heterogeneous structure with spherical nanoparticle inclusions when the oxygen concentration is increased. The optical properties were determined by spectroscopic ellipsometry and UV–Vis–NIR and FTIR spectrophotometry. A comprehensive analysis of the film properties allowed an accurate modelling of the optical constants of the AlyTi1-y(OxN1-x) in the whole wavelength range of solar interest (from 190 nm to 25 µm). It points to a transition from metallic to dielectric behaviour with increasing oxygen content. Consequently, it is demonstrated that the optical properties of these AlyTi1-y(OxN1-x) deposited films can be controlled in a wide range from metallic to dielectric character by adjusting the oxygen concentration, opening a huge range of possibilities for the design of solar selective coatings (SSC) based on this material. Complete SSC, including a TiN layer as IR reflector, were designed by applying optical simulations, obtaining excellent optical selective properties of α=94.0% and εRT = 4.8%.

Made available in DSpace on 2017-07-10T19:24:30Z (GMT). No. of bitstreams: 1 LUIZ HENRIQUE BASSO.pdf: 2154844 bytes, checksum: 4e4e8b56f9c25a2ef13e0c7368a8197b (MD5) Previous issue date: 2008-06-27 / The awareness of the importance of the environment has stimulated the study of new energy sources renewed and less pollutant. Amongst these sources, solar energy stands alone for being perennial and clean. The use of solar energy in systems of residential water heating, instead of the electric shower, can compliment the economy of electric energy, based of the Brazilian energy matrix. To know all the factors that influence the operation of a system of water heating by solar energy is important in the determination of its economic viabilities, techniques and, distribution targeting in urban and agricultural residences. To evaluate equipment of water heating for solar energy in the region west of the Paraná, an archetype with similar characteristics to equipment used in residences for two inhabitants was built, to function with natural circulation or thermosiphon and without help of a complementary heating system. The room temperature and the speed of the wind were also evaluated, verifying its influence in the heating system. The equipment revealed technical viability, reaching the minimum temperature of 35°C for shower, whenever the solar radiation was above the 3500 W.m-2, for the majority of the studied days. The system operated without interruptions and it did not need maintenance, except for the monthly glass cleaning. Economic viability was clearly demonstrated since the useful life of the equipment exceeded the period of use to gain its investment. / A conscientização da importância do meio ambiente tem incentivado o estudo de novas fontes energéticas renováveis e menos poluentes. Dentre essas fontes, a energia solar se destaca por ser perene e limpa. A utilização da energia solar em sistemas de aquecimento de água residenciais, pela substituição do chuveiro elétrico, pode colaborar com a economia de energia elétrica, base da matriz energética brasileira. Conhecer todos os fatores que influenciam a operação de um sistema de aquecimento de água por energia solar é importante na determinação de suas viabilidades técnica e econômica, visando sua difusão em residências urbanas e rurais. Para avaliar um equipamento de aquecimento de água por energia solar na região oeste do Paraná, construiu-se um protótipo com características similares a um equipamento utilizado em residências para dois habitantes, para funcionar com circulação natural ou termossifão e sem auxílio de sistema de aquecimento complementar. A temperatura ambiente e a velocidade do vento também foram avaliadas, verificando-se sua influência no sistema de aquecimento. O equipamento mostrou-se viável tecnicamente, alcançando a temperatura mínima de 35°C para banho, sempre que a radiação solar foi superior a 3500 W.m-2, o que aconteceu para a maioria dos dias estudados. O sistema operou sem interrupções e não necessitou de manutenção, exceto pela limpeza mensal do vidro. Constatou-se a viabilidade econômica, já que a vida útil do equipamento é superior ao período de retorno do investimento.

Made available in DSpace on 2017-05-12T14:47:49Z (GMT). No. of bitstreams: 1 LUIZ HENRIQUE BASSO.pdf: 2154844 bytes, checksum: 4e4e8b56f9c25a2ef13e0c7368a8197b (MD5) Previous issue date: 2008-06-27 / The awareness of the importance of the environment has stimulated the study of new energy sources renewed and less pollutant. Amongst these sources, solar energy stands alone for being perennial and clean. The use of solar energy in systems of residential water heating, instead of the electric shower, can compliment the economy of electric energy, based of the Brazilian energy matrix. To know all the factors that influence the operation of a system of water heating by solar energy is important in the determination of its economic viabilities, techniques and, distribution targeting in urban and agricultural residences. To evaluate equipment of water heating for solar energy in the region west of the Paraná, an archetype with similar characteristics to equipment used in residences for two inhabitants was built, to function with natural circulation or thermosiphon and without help of a complementary heating system. The room temperature and the speed of the wind were also evaluated, verifying its influence in the heating system. The equipment revealed technical viability, reaching the minimum temperature of 35°C for shower, whenever the solar radiation was above the 3500 W.m-2, for the majority of the studied days. The system operated without interruptions and it did not need maintenance, except for the monthly glass cleaning. Economic viability was clearly demonstrated since the useful life of the equipment exceeded the period of use to gain its investment. / A conscientização da importância do meio ambiente tem incentivado o estudo de novas fontes energéticas renováveis e menos poluentes. Dentre essas fontes, a energia solar se destaca por ser perene e limpa. A utilização da energia solar em sistemas de aquecimento de água residenciais, pela substituição do chuveiro elétrico, pode colaborar com a economia de energia elétrica, base da matriz energética brasileira. Conhecer todos os fatores que influenciam a operação de um sistema de aquecimento de água por energia solar é importante na determinação de suas viabilidades técnica e econômica, visando sua difusão em residências urbanas e rurais. Para avaliar um equipamento de aquecimento de água por energia solar na região oeste do Paraná, construiu-se um protótipo com características similares a um equipamento utilizado em residências para dois habitantes, para funcionar com circulação natural ou termossifão e sem auxílio de sistema de aquecimento complementar. A temperatura ambiente e a velocidade do vento também foram avaliadas, verificando-se sua influência no sistema de aquecimento. O equipamento mostrou-se viável tecnicamente, alcançando a temperatura mínima de 35°C para banho, sempre que a radiação solar foi superior a 3500 W.m-2, o que aconteceu para a maioria dos dias estudados. O sistema operou sem interrupções e não necessitou de manutenção, exceto pela limpeza mensal do vidro. Constatou-se a viabilidade econômica, já que a vida útil do equipamento é superior ao período de retorno do investimento.