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%.

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.