Tele-experimentação de técnicas de monitorização via internet com aplicações em agricultura e energia solar (TeleAgriSol)

Tele-experimentação detécnicas de monitorização via Internet com aplicações em agricultura e energia solar.

Dessalinização da água do mar através da energia solar: caso de estudo: Salamansa - Cabo Verde

Dissertação de mest., Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012

Estudo da aplicação de um sistema frigorífico de absorção movido a energia solar na Ilha do Príncipe

Dissertação de mest., Energias Renováveis e Gestão de Energia (Tecnológica), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012

Cartografia solar: estimativa do potencial solar no município de Albufeira

A dependência energética dos combustíveis fósseis é, reconhecidamente, uma das principiais inquietações das economias mundiais. Questões como a concentração de gases de efeito de estufa, poluição atmosférica e o facto de estes combustíveis serem esgotáveis estão cada vez mais no centro das atenções globais, ao que se associa um aumento significativo da população mundial e por conseguinte, dos consumos. Contudo, começa a ser notório um empenho na procura de soluções viáveis que possam contornar esta dependência, nomeadamente no desenvolvimento de tecnologia que permita o aproveitamento de fontes de energias renováveis. Neste sentido, Portugal encontra-se numa posição privilegiada sendo, dos países da europa, o que apresenta índices mais elevados de radiação solar por unidade de superfície, em média cerca de 1500kWh/m2/ano. O sucesso do aproveitamento de fontes de energia renováveis vai depender, em muito, da análise e compreensão do potencial determinado pelas realidades locais, pelos dados meteorológicos, pelas tecnologias existentes e por fatores económicos. (WITTMAN et al., 1997). O processo para estimativa o potencial não é simples e implica uma interação disciplinar; no entanto tendem a aparecer modelos que, a montante do processo, simplificam a análise espacial da energia solar. Neste campo, o contributo dos Sistemas de Informação Geográfica tem sido fundamental, oferecendo um conjunto de ferramentas de processamento de dados bastantes úteis para a modelação solar. A presente dissertação combina a utilização dos SIG com a análise do potencial solar, apresentando como objetivos principais: i) a estimativa do potencial solar no Município de Albufeira e ii) a criação de uma aplicação que disponibilize os resultados através da web, facilitando a consulta e análise espacial dos mesmos.

Comparação energética de sistemas de aquecimento a energia solar para o conforto térmico dos ocupantes de um edifício residencial

Dissertação de mestrado, Energia e Climatização de Edifícios, Instituto Superior de Engenharia, Universidade do Algarve, 2015

Enabling solar electricity with electric vehicles in future energy systems

Tese de doutoramento, Sistemas Sustentáveis de Energia, Universidade de Lisboa, Faculdade de Ciências, 2015

An Analysis of Local Wind and Air Mass Directions and Their Impact on Cladosporium Distribution Using HYSPLIT and Circular Statistics

Ecological studies that examine species-environment relationships are often limited to several meteorological parameters, i.e. mean air temperature, relative humidity, precipitation, vapour pressure deficit and solar radiation. The impact of local wind, its speed and direction are less commonly investigated in aerobiological surveys mainly due to difficulties related to the employment of specific analytical tools and interpretation of their outputs. Identification of inoculum sources of economically important plant pathogens, as well as highly allergenic bioaerosols like Cladosporium species, has not been yet explored with remote sensing data and atmospheric models such as Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT). We, therefore, performed an analysis of 24 h intra-diurnal cycle of Cladosporium spp. spores from an urban site in connection with both the local wind direction and overall air mass direction computed by HYSPLIT. The observational method was a volumetric air sampler of the Hirst design with 1 h time resolution and corresponding optical detection of fungal spores with light microscopy. The atmospheric modelling was done using the on-line data set from GDAS with 1° resolution and circular statistical methods. Our results showed stronger, statistically significant correlation (p ≤ 0.05) between high Cladosporium spp. spore concentration and air mass direction compared to the local wind direction. This suggested that a large fraction of the investigated fungal spores had a regional origin and must be located more than a few kilometers away from the sampling point.

Adipose stromal vascular fraction cell sheets as vascular strategies for tissue engineering and regenerative medicine applications

Tese de mestrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2015

Modelling real solar cell using PSCAD/MATLAB

This paper presents the development of a solar photovoltaic (PV) model based on PSCAD/EMTDC - Power System Computer Aided Design – including a mathematical model study. An additional algorithm has been implemented in MATLAB software in order to calculate several parameters required by the PSCAD developed model. All the simulation study has been performed in PSCAD/MATLAB software simulation tool. A real data base concerning irradiance, cell temperature and PV power generation was used in order to support the evaluation of the implemented PV model.

Central de produção de energia eléctrica a partir de energia solar térmica

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

Structural modification of TiO2 nanorod films with an influence on the photovoltaic efficiency of a dye-sensitized solar cell (DSSC).

TiO2 nanorod films have been deposited on ITO substrates by dc reactive magnetron sputtering technique. The structures of these nanorod films were modified by the variation of the oxygen pressure during the sputtering process. Although all these TiO2 nanorod films deposited at different oxygen pressures show an anatase structure, the orientation of the nanorod films varies with the oxygen pressure. Only a very weak (101) diffraction peak can be observed for the TiO2 nanorod film prepared at low oxygen pressure. However, as the oxygen pressure is increased, the (220) diffraction peak appears and the intensity of this diffraction peak is increased with the oxygen pressure. The results of the SEM show that these TiO2 nanorods are perpendicular to the ITO substrate. At low oxygen pressure, these sputtered TiO2 nanorods stick together and have a dense structure. As the oxygen pressure is increased, these sputtered TiO2 nanorods get separated gradually and have a porous structure. The optical transmittance of these TiO2 nanorod films has been measured and then fitted by OJL model. The porosities of the TiO2 nanorod films have been calculated. The TiO2 nanorod film prepared at high oxygen pressure shows a high porosity. The dye-sensitized solar cells (DSSCs) have been assembled using these TiO2 nanorod films prepared at different oxygen pressures as photoelectrode. The optimum performance was achieved for the DSSC using the TiO2 nanorod film with the highest (220) diffraction peak and the highest porosity.

Effects of sulphurization time on Cu2ZnSnS4 absorbers and thin films solar cells obtained from metallic precursors

We report the results of a study of the sulphurization time effects on Cu2ZnSnS4 absorbers and thin film solar cells prepared from dc-sputtered tackedmetallic precursors. Three different time intervals, 10 min, 30min and 60 min, at maximum sulphurization temperature were considered. The effects of this parameter' change were studied both on the absorber layer properties and on the final solar cell performance. The composition, structure, morphology and thicknesses of the CZTS layers were analyzed. The electrical characterization of the absorber layer was carried out by measuring the transversal electrical resistance of the samples as a function of temperature. This study shows an increase of the conductivity activation energy from 10 meV to 54meV for increasing sulphurization time from 10min to 60min. The solar cells were built with the following structure: SLG/Mo/CZTS/CdS/i-ZnO/ZnO:Al/Ni:Al grid. Several ac response equivalent circuit models were tested to fit impedance measurements. The best results were used to extract the device series and shunt resistances and capacitances. Absorber layer's electronic properties were also determined using the Mott–Schottky method. The results show a decrease of the average acceptor doping density and built-in voltage, from 2.0 1017 cm−3 to 6.5 1015 cm−3 and from 0.71 V to 0.51 V, respectively, with increasing sulphurization time. These results also show an increase of the depletion region width from approximately 90 nm–250 nm.

Planeamento de curto prazo de sistemas de energia solar usando técnicas de otimização robusta

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica

Growth and characterization of Cu2ZnSn(S,Se)4 thin films for solar cells

Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with their band gap energies around 1.45 eV and 1.0 eV, respectively, can be used as the absorber layer in thin film solar cells. By using a mixture of both compounds, Cu2ZnSn(S,Se)4 (CZTSSe), a band gap tuning may be possible. The latter material has already shown promising results such as solar cell efficiencies up to 10.1%. In this work, CZTSSe thin films were grown in order to study its structure and to establish the best growth precursors. SEM micrographs reveal an open columnar structure for most samples and EDS composition profiling of the cross sections show different selenium gradients. X-ray diffractograms show different shifts of the kesterite/stannite (1 1 2) peak, which indicate the presence of CZTSSe. From Raman scattering analysis, it was concluded that all samples had traces of CZTS and CZTSSe. The composition of the CZTSSe layer was estimated using X-ray diffraction and Raman scattering and both results were compared. It was concluded that Se diffused more easily in precursors with ternary Cu–Sn–S phases and metallic Zn than in precursors with ZnS and/or CZTS already formed. It was also showed that a combination of X-ray diffraction and Raman scattering can be used to estimate the ratio of S per Se in CZTSSe samples.

Novos compostos orgânicos reticuláveis para aplicações em células fotovoltaicas

Trabalho Final de Mestrado para obtenção do grau de mestre em Engenharia Química e Biológica