Resumen Las aplicaciones de la energía solar térmica de concentración (CST) están creciendo en todo el mundo, especialmente en los procesos combinados de refrigeración, calor y electricidad. Partiendo del análisis del confort térmico de un edificio y de simulaciones de software para CST, el presente estudio evalúa un sistema de acondicionamiento solar integrado con sistemas de absorción. El sistema de refrigeración está equipado con configuraciones de ciclo de efecto simple, doble y triple, parámetros de producción y almacenamiento térmico. Se estima la fracción de energía auxiliar necesaria para el funcionamiento del sistema. Los resultados indican que el sistema de doble efecto es la mejor configuración para la ubicación adoptada en Brasil. La demanda anual de energía auxiliar del sistema es, aproximadamente, del 20%. Los sistemas de triple efecto requieren menos energía a temperaturas más altas debido a la radiación directa local, lo que lleva a un funcionamiento intermitente y a una mayor demanda de energía auxiliar. La metodología aplicada en este trabajo podría adoptarse en diferentes lugares, haciendo hincapié en la posibilidad de probar sistemas de menor escala en edificios pequeños.

Abstract Concentrating solar thermal (CST) energy applications are growing worldwide, especially in combined cooling, heat, and power processes. Building upon the analysis of a building’s thermal comfort, and software simulations for CST, the current study evaluates a solar conditioning system integrated with absorption systems. The cooling system is equipped with single-, double- and triple-effect configurations cycle, production parameters, and thermal storage. The required fraction of auxiliary energy for the system operation is estimated. The results indicate that the double effect system is the best configuration for the adopted location in Brazil. The system’s annual auxiliary energy demand is, approximately, 20%. Triple-effect systems require less energy at higher temperatures due to local direct radiation, which then leads to an intermittent operation and greater auxiliary energy demands. The methodology applied in this work could be adopted in different locations, with an emphasis on the possibility of testing smaller scale systems in small buildings.

The shaft furnace knowed Midrex™ is used for the production of direct reduced iron with the use of reformed gas. Another process based on shaft reactors is the Tecnored process, which exhibits the great advantage of using self-reducing agglomerates. Therefore, it was proposed a combination of the shaft furnace for direct reduction with self-reducing pellet burden. In addition, with the aim of improving the furnace efficiency and reducing the need for reformed gas, the injection of natural gas and oxygen into the bustle region is proposed. Thus, it is possible exploit the advantages of direct reduction involving high amounts of hydrogen and faster reactions of the self-reducing process to decrease the CO2 emission, compared to that of blast furnace. The energy profile, productivity, and carbon emission of the traditional shaft furnace were compared with the simulated results after partial replacement of the burden with self-reducing pellets containing fines of elephant grass charcoal. The simulation results for a combination of 15% of self-reducing pellets in the burden with 2.5% oxygen and natural gas injection were the best among the scenarios simulated, with the productivity being 2.7 ton/m3 day and the decrease in the amount of reformed gas being 10%.

Abstract A numerical model based on transport equations for momentum, energy and chemical species for the gas and solid phases is proposed to simulate the inner phenomena in the direct reduction of the shaft furnace process for producing directly reduced iron (DRI). The model is verified using industrial data for productivity, raw materials and final composition of the DRI product. The model is used to evaluate operational practices using new raw materials and the composition of the reducing gas in the process. Three cases were considered, which correspond to available raw materials commercialized by different suppliers. The effects on the gas and solid inner temperatures, pressure and phase composition distributions are quantified. The simulation results indicated that good agreement for overall parameters of the process could be achieved and afterwards, detailed features of the inner conditions of the process are predicted.

Resumo Minas Gerais convive, há décadas, com o desafio da sofisticação econômica. Na tentativa de construir caminhos para a transformação de sua economia, o governo de Minas Gerais lançou a plataforma Dataviva, possibilitando a aplicação da abordagem da complexidade econômica no âmbito de políticas públicas de desenvolvimento. O artigo visa contribuir para essa reflexão, por meio da análise da complexidade econômica dos estados brasileiros no período entre 2002 e 2014, com foco em Minas Gerais. A pesquisa revela que a economia mineira está presa em uma “armadilha de baixa complexidade”, o que demanda uma intensa colaboração entre os setores público e privado para a descoberta e investimento em atividades que contribuam para a sofisticação econômica.

Abstract Minas Gerais has dealt for decades with the challenge of economic sophistication. In an attempt to build paths for its economy’s transformation, the Government of Minas Gerais launched the Dataviva platform, allowing economic complexity’s approach to be used in the context of public development policies. This article aims to contribute to this debate by analyzing the economic complexity of the Brazilian states from 2002 to 2014, focusing on Minas Gerais. The research reveals that Minas’ economy is stuck in a “low complexity trap”, which requires a close collaboration between the public and private sectors for the discovery and investment in activities that contribute to economic sophistication.

This work focused on the characterization physical and microstructural of the self-reducing pellet made of Electric Arc Furnace (EAF) dust using different low cost techniques. The serial sectioning technique was used to evaluate detailed measurements of pore connections, tortuositiy of pores and porosity distribution. The chemical analysis using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES), Scanning Electron Microscopy (SEM), Optical Microscopy (OM) and X-ray diffraction were carried out to identify the common phases presented in EAF dust agglomerate. It was observed that the pellet phase composition is formed by iron as magnetite, metallic iron, wustite, and zinc ferrite. The visualization of the reconstructed 3D microstructure provided average qualitative and quantitative analysis of the porosity (41.61%), a consistent result and in accordance with that obtained by pycnometry technique (41.53%). As expected, these results are more precise when compared with the result obtained by two-dimensional technique (23.41%). In addition, it was calculated the value of the tortuosity parameter (0.84) that suggested a morphological structure closest to cylindrical shape.