Materiais para a Energia - ME
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- Estudo de perspectivas de desenvolvimento do sector das madeiras nos AçoresPublication . Marques, José Armando Nunes; Santos, José António dosAtendendo ao interesse que o sector de madeiras tem para os Açores o Instituto de Inovação Tecnológica dos Açores - INOVA, encomendou à Unidade Tecnológica para as Indústrias da Madeira e da Cortiça - UTMC do Laboratório Nacional de Engenharia e Tecnologia Industrial - LNETI, um estudo de desenvolvimento do sector de madeiras, o qual foi concretizado através de visitas, entrevistas e contactos vários por dois técnicos desta unidade, que se deslocaram à região entre os dias 28 de Maio e 7 de Junho. Foram visitadas as ilhas da Terceira, Faial, Pico e S. Miguel, tendo-se em cada ilha observado o tecido industrial existente, bem como as disponibilidades em matérias-primas. É o resultado destes trabalhos que seguidamente se descreve, procurando no final, indicar vectores e acções possíveis para o desenvolvimento do sector.
- Desenvolvimento de um equipamento de ensaio e estudo do comportamento à fluência de componentes estruturais em madeiraPublication . Santos, José António dos; Pinho, C. Marques; Regufe, Francisco
- Avaliação do módulo de elasticidade à flexão como ferramenta do controlo da qualidade em vigas lameladas coladas em madeiraPublication . Santos, José António dos; Pinho, C. Marques
- Effect of vanadium and carbon content on the sinterability of water atomised high speed steel powdersPublication . Mascarenhas, João; Oliveira, M. Manuela; Wright, C. S.This paper presents the results of an investigation into the sintering behaviour of three vanadium enriched variants of T42 high-speed steel. Powders were prepared by water atomization with vanadium and carbon contents of 6-8 wt% and 2.2 -2.7 wt%, respectively. These were annealed, die pressed and sintered in vacuum. All three alloys were sintered to full density giving "as-sintered" microstructures comprising globular MC carbides dispersed in a martensitic matrix. Optimum sintering temperatures were in the range 1240-1250 degrees C with lower optimum temperatures associated with higher carbon levels. Sintering characteristics are correlated with phase diagrams calculated using ThermoCalc (TM) software and TCFe2000 database. The implications for the design of sinterable vanadium containing high-speed steels are discussed.
- Lead bioremoval by cork residues as biosorbentPublication . Mota, Dora; Marques, Paula; Rosa, Maria Fernanda; Gil, Luís; Marques, Carlos PereiraThe intensification of industrial activity during the last few years has greatly contributed to the increase of heavy metals in the environment, mainly in the aquatic systems [1]. Conventional technologies traditionally used for the removal of heavy metals from aqueous solutions are expensive and inefficient at low metal concentrations [2]. Biosorption, which is a property of different types of biomass (biosorbents) to bind and concentrate heavy metals from even very dilute aqueous solutions, is one of the most promising technologies that can be used for this purpose [3]. The goal of this work was to study the bioremoval process of Pb(II) ions from aqueous dilute solutions by cork granulates (1-2 mm) from a Portuguese cork processing company. The effect of physico-chemical parameters such as initial metal solution, pH, biomass cork pre-treatments and initial metal and biosorbent concentrations on the metal removal efficiency were investigated. The maximum Pb(II) uptake capacity (Qmax) of cork biomass was also determined from the Langmuir isotherm. The results obtained showed that the optimum initial pH for Pb(II) removal was in the range 3-4, leading to removal yields of about 90-100% for initial metal concentrations of 10-100 mg/L. Cork biomass without treatment provided a higher removal yield (93%) than the biomass submitted to previous extraction with deionised water (80%), ethyl acetate (83%) and ethanol (88 %). The Langmuir model showed a very good correlation with experimental results (r2=0.995) and the Qmax was determined as being 5.3 mg Pb(II)/g cork. The optimisation of continuous bioremoval of Pb(II) (10 mg/L) from 25 L of influent, regarding metal uptake yield and volume of effluent containing a Pb(II) concentration 1 mg/L (MAV), was carried out by the factorial design methodology, leading to the establishment of the best operating conditions. In these conditions, two fixed bed-reactors (operational liquid volume of each reactor containing 20g of biosorbent=138 mL) running in sequential mode (feed flow rate - 590 mL/h) were more efficient (effluent volume with [Pb(II)] 1 mg/L=10 L) than one reactor alone (effluent volume with [Pb(II)] 1 mg/L=5 L). Finally, the chemical characterization in terms of CQO, TOC and phenolic compounds of the effluent before discharge showed that all values were lower than the ones allowed by environmental legislation.
- Breve história das tintas antivegetativasPublication . Almeida, Maria Elisabete; Cunha Diamantino, Teresa; Sousa, Orlando deNeste trabalho, os autores apresentam uma panorâmica geral sobre as tintas antivegetativas. Após a conveniente localização destas tintas no esquema de protecção anticorrosiva das obras vivas dos navios e/ ou outras estruturas móveis, fazem uma síntese dos principais tipos de produtos antivegetativos usados ao longo dos tempos, até aos nossos dias. Complementarmente, sistematizam as principais tipologias dos organismos vivos que se fixam nas obras vivas das embarcações e referem alguns tipos de fauna e flora predominantes em duas regiões da Ibero-América. Abordam também, ainda que sumariamente, os principais mecanismos básicos de funcionamento dos diferentes tipos de tintas antivegetativas. Finalmente, referem algumas das principais linhas de investigação actualmente em curso, no domínio da luta contra a fixação dos organismos marinhos nos cascos dos navios
- Manufacture of cordierite foams by direct foamingPublication . Silva, Elisabete Ribeiro; Correia, N.; Silva, J. M.; Oliveira, Fernando Almeida Costa; Ribeiro, F. R. M. C.; Bordalo, J. C.; Ribeiro, M. F.Open cell cordiereti fosms were prepared by a direct foaming two-component polyurethane (PUR)/ceramic system. Throught optimization of several experimental parameters such as contents of catalysts and ceramic cordiereti precursor, as well as plasticizer presence, foams with porosites 85-95&% and densities ranging from 130-410 kg/m3 were obtained. Thse foams characteristics make them attractive to be used as catalyst supports. The new two-component PUR/ceramics system developped allows the high solid's loading (higher than 40 wt. %). Finer ceramic particles in this system provide better particles packaged and cohesion upon sintering, favouring the cordiereti foam stability.
- Integrating hydrogen generation and storage in a novel compact electrochemical system based on metal hydridesPublication . Rangel, C. M.; Fernandes, Vitor; Slavkov, Y.; Bozukov, Latchezar N.A novel electrochemical system has been developed which integrates hydrogen production, storage and compression in only one device, at relatively low cost and high efficiency. The development of efficient and reliable energy storage systems based on hydrogen technology represents a challenge to seasonal storage based on renewable hydrogen. State of the art renewable energy generation systems include separate units such as electrolyser, hydrogen storage vessel and a fuel cell system for the conversion of H2 back into electricity, when required. In this work, a compact unit integrating production and storage is proposed. The developed prototype comprises a six electrode cell assembly using an AB5 type metal hydride and Ni plates as counterelectrodes, in a 35 wt% KOH solution. During charging, hydrogen is absorbed in the metal hydride and corresponding oxygen is conveyed out of the system. Conversely, in the case of discharging hydrogen stored in the metal hydride is released to an external H2 storage. In the present prototype, released hydrogen was delivered into the hydrogen storage up to a pressure of 15 Bar. Metal hydride electrodes with chemical composition LaNi4.3Co0.4Al0.3 were prepared by high frequency vacuum melting followed by high temperature annealing at 1000O C during 8 hours. X-Ray phase analysis showed typical hexagonal structure and no traces of other intermetallic compounds belonging to the La-Ni phase diagram. Thermodynamic study has been performed in a Sieverts type of apparatus produced by Labtech. Int. During cycling, charging was run at 40 A at cell voltages of 1.7 V for two hours which corresponds to C/2 charging time. Hydrogen was released by applying a constant current of 40A for two hours until cell voltage rise from 0.5 to 1.7V, at the end of the processes. The process was studied in-situ using a gas chromatograph from Agilent. It is anticipated that the device will be integrated as a combined hydrogen generator and storage unit in a stand alone system associated to a 1 kW fuel cell.
- Novel hydrogen generator: storage based on metal hydridesPublication . Rangel, C. M.; Fernandes, Vitor; Slavkov, Y.; Bozukov, Latchezar N.A novel electrochemical system has been developed which integrates hydrogen production, storage and compression in only one device, at relatively low cost and high efficiency. The prototype comprises a six electrode cell assembly using an AB5 type metal hydride and Ni plates as counter electrodes, in a KOH solution. Metal hydride electrodes with chemical composition LaNi4.3Co0.4Al0.3 has been prepared by high frequency vacuum melting followed by high temperature annealing. X-Ray phase analysis showed typical hexagonal structure and no traces of other intermetallic compounds belonging to the La-Ni phase diagram. Thermodynamic study of the alloy has been performed in a Sieverts type apparatus produced by Labtech. Ltd. In the present prototype during charging, hydrogen is absorbed in the metal hydride and corresponding oxygen is conveyed out of the system. Conversely, in the case of discharging the hydrogen stored in the metal hydride it is released to an external H2 storage. Released hydrogen is delivered into the hydrogen storage up to a pressure of 15 bar. In this work, a compact unit integrating production, storage and compressing hydrogen is proposed as one device at relatively low cost and higher efficiency than a classical electrolyser. It is anticipated that the device will be integrated as a combined hydrogen generator in a stand alone system associated to a 1 kW fuel cell.
- Metallurgical evaluation of laser sintered M3/2 HSS powderPublication . Martins, Isabel M.; Esperto, Luís; Domingues, Joaquim Resina; Santos, Mário J. G.Direct Metal Laser Sintering (DMLS) is one of the leading commercial rapid tooling (RT) technologies that produce 3D fully functional parts and tools directly from a CAD model. High Speed Steels (HSS) have the desired combination of hot hardness, wear resistance and toughness needed for applications such as cutting tools, special tools, inserts and dies that can be successfully developed in a near net shape by DMLS. This paper presents a study of DMLS of commercial water atomized M3/2 powder with different apparent densities. The effect of apparent density and DMLS process parameters on the surface morphologies and microstructure of laser sintered M3/2 powder was analysed and the optimum processing conditions to reduce balling effect were identified. Laser sintered M3/2 HSS with energy densities between 2.4 and 12 J/mm2 produced a coarse roughness (Rz) ranging from 135 to 234μm. The lowest roughness (65μm) was obtained with 36J/mm2, the highest laser energy density value used. The microstructure of laser sintered M3/2 HSS consisted of austenite, martensite and a fine carbide structure.