17 research outputs found
Multiple Regression Analysis in the Development of NiFe Cells as Energy Storage Solutions for Intermittent Power Sources Such as Wind or Solar
Multiple regression analysis was used to investigate the effect of bismuth sulphide and iron sulphide as anode additives for NiFe cells. With this in mind, in-house made Fe/FeS/Bi2S3 based electrodes were cycled against commercially available nickel electrodes. A simplex centroid design was used to investigate the combined effects of any of the aforementioned additives on cell performance. The manuscript ends with an initial look at electrolyte systems as a means to further improve the performance of our cells. Finally, our findings support the idea that HS- ions improve the overall performance of NiFe cells
Aqueous batteries as grid scale energy storage solutions
Energy storage technologies are required to make full use of renewable energy sources, and electrochemical
cells offer a great deal flexibility in the design of energy systems. For large scale electrochemical
storage to be viable, the materials employed and device production methods need to be low cost, devices
should be long lasting and safety during operation is of utmost importance. Energy and power densities
are of lesser concern. For these reasons, battery chemistries that make use of aqueous electrolytes are
favorable candidates where large quantities of energy need to be stored. Herein we describe several
different aqueous based battery chemistries and identify some of the research challenges currently
hindering their wider adoption. Lead acid batteries represent a mature technology that currently dominates
the battery market, however there remain challenges that may prevent their future use at the
large scale. Nickel–iron batteries have received a resurgence of interest of late and are known for their
long cycle lives and robust nature however improvements in efficiency are needed in order to make them
competitive. Other technologies that use aqueous electrolytes and have the potential to be useful in
future large-scale applications are briefly introduced. Recent investigations in to the design of nickel–iron
cells are reported with it being shown that electrolyte decomposition can be virtually eliminated by
employing relatively large concentrations of iron sulfide in the electrode mixture, however this is at the
expense of capacity and cycle life
Sheds extratores e captadores de ar: influência da geometria e da dimensão das aberturas no desempenho da ventilação natural nas edificações
Resumo A ventilação natural é uma eficiente estratégia projetual para o condicionamento térmico passivo de edificações, ocorrendo por ação dos ventos, efeito chaminé ou pela combinação de ambos. Dentre as estratégias de ventilação, destacam-se os sheds, aberturas no telhado, que funcionam como captadores ou extratores de ar, dependendo de sua localização em relação aos ventos dominantes. O objetivo desse artigo é avaliar a influência da variação na geometria dos sheds e na dimensão das aberturas de entrada e saída de ar no desempenho da ventilação natural. O sistema foi avaliado para os ângulos de incidência dos ventos externos de 0° e 45° (extração) e 135° e 180° (captação). A metodologia adotada foi a simulação por Dinâmica dos Fluídos Computacional (CFD), utilizando como ferramenta o software CFX. Foram realizadas análises quantitativas (taxas de renovação de ar/hora e coeficiente de pressão nas aberturas) e qualitativas (planos de contorno e vetores de direção e intensidade do fluxo de ar). Os resultados indicam que sheds com geometrias aerodinâmicas e o aumento das aberturas de saída de ar incrementam o fluxo de ar interno. Para os sheds captadores o aumento isolado das aberturas de entrada de ar não proporciona uma melhora significativa na captação dos ventos pela cobertura