Este artículo presenta los resultados del análisis técnico (basado en la cantidad de exergía) y ambiental de una planta termoeléctrica de 50 MWe nominales, localizada al sur del estado de Santa Catarina (Brasil), diseñada para operar con carbón pulverizado y adaptada para operar en proceso co-firing carbón-biomasa residual. Además de la planta termoeléctrica, el estudio consideró una frontera extendida que involucró los procesos relacionados con la obtención, transporte y manipulación tanto del carbón como de la biomasa. El análisis exergético siguió lineamentos de la segunda ley de la termodinámica, mientras que el análisis ambiental se realizó siguiendo la metodología de análisis de ciclo de vida (ACV), considerando 1 MWh como unidad funcional y la categoría de impacto en el calentamiento global, mediante el método IPCC 2007 GWP 100 años. Para ambos casos (operación solo con carbón y en co-firing), el análisis exergético indicó que la planta termoeléctrica responde por más del 95 % del total de la exergía consumida. Para el análisis ambiental, los resultados indicaron que para la operación solo con carbón se emiten 1230 kg de CO2-eq por MWh, mientras que para la operación en co-firing, con una participación de hasta 10 % de biomasa en base energética, el valor efectivo de la emisión fue de 1103 kg de CO2-eq por MWh.

This paper presents a technical (based on the exergy amount) and environmental analysis concerning an existing 50 MWe steam power plant located in the south of the Santa Catarina state - Brazil, designed to operate with pulverized coal and modified to operate in co-firing process with coal-biomass. In addition to the power plant, the study considered an extended boundary that involves the processes related to the obtaining, transportation, and handling of both coal and biomass. The exergy analysis was focused in the second law of thermodynamics, while the environmental analysis followed the Life Cycle Assessment (LCA) methodology, taking into account 1 MWh as functional unit and the global warming impact category, following the IPCC GWP index, over 100 years. For both cases (only coal and co-firing), the exergetic analysis indicated that the power plant is responsible for over 95 % of the exergy consumption. Results indicated that for the case of operating only with coal, 1,230 kg of CO2 e per MWh are emitted, whereas for operation in co-firing, with a share of 10% of biomass on energy basis, this amount changes to 1,103 kg CO2 per MWh.

Sintered metallic porous structures have an application as capillary structures in two-phase heat transfer loops. In this work the manufacturing procedure of tubular porous structures for capillary pump application is discussed. The application of porous structures on capillary pumping systems requires porosity higher than 40% and pore size diameter lower than 20 µm. Carbonyl nickel powder with particle diameter between 3 and 7 µm and stainless steel AISI316L powder with particle diameter between 1 and 22 µm were used as raw material. Sintering under hydrogen atmosphere was performed both in a resistive furnace and in a plasma reactor. Temperature and time were the modified parameters to obtain suitable porosity and roundness on the samples. The porosity was measured using the Arquimedes Principle (MPIF-42), the roundness was evaluated using a simplified measurement technique of the sample diameter and the pore size distribution was determined by image analysis techniques. Images obtained by Scanning Electronic Microscopy were employed on the image analysis. The sintering parameters selected to manufacture nickel samples were 700 °C and 30 min resulting in a porosity of about 44%. The sintering parameters selected to manufacture stainless steel samples were 1000 °C and 30 min resulting in a porosity of about 40%.

Sintered nickel powder is proposed to be used as porous wicks in heat pipes and capillary pumps. In this work the manufacturing procedure for tubular wicks for capillary pump application is discussed. The porosity, mechanical resistance and roundness of tubular wicks made of carbonila powder, atomized powder and a powder mixture of both are analyzed. A powder mixture was selected as the best raw material. In this case, pore size in the range of 2 to 24 <FONT FACE="Symbol">m</font>m and porosity about 50% were measured. First tests carried out in the laboratory, using acetone as the working fluid, show capillary pumping pressures up to 4 kPa and heat fluxes of about 1 W/cm2 in a two-phase heat transfer loop.