http://hdl.handle.net/10174/916 2026-04-04T08:19:59Z http://hdl.handle.net/10174/5983 Title: Energia da biomassa Authors: Malico, Isabel Abstract: Valorização energética de biomassa. 2008-01-01T00:00:00Z http://hdl.handle.net/10174/5840 Title: Analysis of a photovoltaic unit using computational fluid dynamics Authors: Fernandes, Gérson; Malico, Isabel; Ferreira de Sousa, Paulo J. S. A.; Pina, Luís Abstract: The use of photovoltaic panels is rising, and its use will play a significant role in achieving the European Union’s target of 20% of energy consumption coming from renewable resources. At the same time, suppliers of solar energy panels aim to optimise the use of photovoltaic cells. This can be done, for example, by using intelligent methods of cooling to gain the maximum electrical output possible, and minimizing cost by reducing the number of cells without compromise in power output. WS Energia, a national market leader in solar technology, has developed proprietary solutions for the harvesting of solar energy. Computational fluid dynamics (CFD) is the method of solving of the Navier-Stokes equations at discrete points via a numerical method. The aim of this study is to use CFD to gain an insight of on two different levels of the photovoltaic unit. The first is to calculate the forces and induced vibrations on the structure with varying wind velocities and profiles. The second objective is to study the heat transfer mechanisms within the solar cell, in order to utilize innovative cooling methods to optimise the electrical output. Preliminary studies consisting of laminar flow in two dimensions have been conducted on a photovoltaic unit. The aim is to validate the computational setup and the turbulence modelling. This will be compared with data aquired in the experimental facilities of WS Energia. More comprehensive simulations are in progress. The commercial Navier-Stokes solver, Ansys Fluent will be used for this study in a newly acquired computational hardware. 2012-01-01T00:00:00Z http://hdl.handle.net/10174/5518 Title: Simulation of a downdraft gasifier Authors: Branquinho, Mónica; Itai, Yuu; Malico, Isabel; Brasil, Augusto C. M. Abstract: The Brazilian electric grid is managed by ELETROBRAS, a company controlled by the Brazilian Government. According to ELETROBRAS there are 1.2 million consumers in the Amazon region that are not connected to the grid. This is a low population density region, with 205 MW of off grid energy production systems installed and highly dependent of petrodiesel. Some authors showed that gasification systems with power below 5 MW have higher efficiencies than combustion systems with steam cycle. Moreover, gasification systems are very suitable to the needs of Amazonian communities: one because of the availability of biomass in the region, and two because of the higher efficiency compared to the systems using combustion and steam turbines. Diesel engines are already in operation in the Amazon region producing electric energy (as long as the small communities are not connected to the grid), and gasification systems would fit the actual infrastructure. However, the potential of biomass as energy resource for small Amazonian communities can only be evaluated through simulation models that can predict the gasification efficiency, the producer gas heating value and the overall electrical efficiency. Apart from woody biomass residues, Açaí seed (Euterpe oleracea Mart.) is the biomass residues most wasted in Pará State (Brazil) due a production of 101 kton/year of that fruit. However, wastes of açaí seeds can be up to 70% moist and that could make the gasification process unviable. Again, numerical simulations can estimate the influence of the moisture content on the gasification process of açaí seeds. The optimization of the gasification of açaí seeds and the resulting composition of the producer gas can be analyzed in two ways that occur simultaneously: first the influence of the air/fuel ratio, and second the influence of the moisture content. Once the producer gas heating value is a consequence of its composition, the optimization of the moisture content and air/fuel ratio would increase the gasification efficiency. This paper presents the implementation and validation of a thermochemical equilibrium model for a downdraft gasifier. The numerical model is validated against the experimental results of Santos. The reactor is a small scale, stratified downdraft open top gasifier fuelled with açaí seeds (Euterpe oleracea Mart.). Syngas compositions obtained for the simulation of several operating conditions is compared with the experimental results. 2012-01-01T00:00:00Z http://hdl.handle.net/10174/1392 Title: A Energia na Universidade de Évora Authors: Malico, Isabel Abstract: Texto relativo à formação e I&D da Universidade de Évora na área da Energia. 2008-05-31T23:00:00Z