The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Inmaculada Canadas - One of the best experts on this subject based on the ideXlab platform.
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sintering of hdh ti powder in a Solar Furnace at plataforma Solar de almeria
Journal of Alloys and Compounds, 2017Co-Authors: Jaroslav Kovacik, Jose Rodriguez, Stefan Emmer, Inmaculada CanadasAbstract:Abstract The brand new technology for sintering of titanium was tested: For the first time, titanium powder was pressure less sintered under argon atmosphere at different temperatures and time, in 5 kW vertical axis Solar Furnace at Plataforma Solar de Almeria (PSA), Spain. The decrease of final porosity with increasing sintering temperature and time at constant heating rate is observed. The obtained results are compared with those obtained for identical green powder compacts sintered in vacuum Furnace. Final porosity below 5% was achieved and shorter sintering times were observed. Radial shrinkage of samples at Solar Furnace is almost the same as at vacuum Furnace. On the contrary axial shrinkage is 20% higher. It was proposed that this can be attributed to argon gas used during sintering and due to the different heating in Solar Furnace during sintering. Argon at lower temperature acts as a heat transfer medium and helps to distribute the heat more homogeneously into the powder compacts. At higher temperature it remains enclosed in the pores thereby increasing a bit final compact porosity when compared with vacuum Furnace. It was further showed that the contents of O, N, H in final compacts depend predominantly on their concentration in original powder. The observed increase due to technology is 300 ppm for oxygen and 80 ppm for nitrogen. Hydrogen concentration decreased significantly. Microhardness dependence on porosity of prepared samples was also investigated and microhardness of bulk Ti prepared in Solar Furnace was estimated to be 282.2 ± 28.3 HV0.5.
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temperature uniformity improvement in a Solar Furnace by indirect heating
Solar Energy, 2016Co-Authors: Fernando Costa A Oliveira, Jose Rodriguez, Inmaculada Canadas, Jorge Cruz Fernandes, Jose Galindo, L.g. RosaAbstract:Abstract The development of materials capable to work under increasingly extreme conditions requires not only higher processing temperatures but also tight control of temperature uniformity. Aiming at developing an indirect heating receiver design to be integrated in novel concentrated Solar Furnace for the thermal processing of materials under controlled heating and homogeneous temperature, graphite disc heat receiver systems with varying thickness, geometry and height from the sample holder at the bottom were tested in two types of gas environments, namely dynamic vacuum and under Ar gas flow. Results acquired were quite encouraging demonstrating feasibility of realizing temperature gradient within circa 50 °C along the height beneath the top graphite disc and the bottom sample holder.
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new psa high concentration Solar Furnace sf40
SOLARPACES 2015: International Conference on Concentrating Solar Power and Chemical Energy Systems, 2016Co-Authors: Jose Rodriguez, Inmaculada Canadas, Eduardo ZarzaAbstract:A new Solar Furnace has been designed and built at Plataforma Solar de Almeria. In this work, its main components such as heliostat, concentrator, attenuator and test table, and the method used to align them are described. Other equipment like the auxiliary systems necessary for the Solar operation, vacuum chamber and gas system are outlined too. Finally, the thermal characteristics of the focus were measured during a test campaign, where different planes along the optical axis were scanned with a radiometer, and the peak flux was obtained and is presented in the last section of this report.
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psa vertical axis Solar Furnace sf5
Energy Procedia, 2014Co-Authors: Jose Rodriguez, Inmaculada Canadas, Eduardo ZarzaAbstract:Abstract A new high-flux vertical axis Solar Furnace has been constructed and is fully operational at Plataforma Solar de Almeria (PSA). This new system is able to deliver up to 5 kW power at peak concentration ratios exceeding 6000. It has been designed to perform tests that require high radiant flux, strong gradients and very high temperatures, and will be devoted for materials treatment at high temperature, under vacuum and controlled atmosphere conditions This new Solar Furnace operates in a vertical axis, i.e. parabolic concentrator and heliostat are vertically aligned on the optical axis of the paraboloid. The main advantage of vertical axis Solar Furnaces is that the samples are deposited, without the need of any fixation, on a horizontal plane where they can be treated directly in the focus or inside crucibles, avoiding problems of loss of material by gravity in those tests in which pre-deposited powders are used, or when the treatment requires surface melting of the specimens, and preventing the use of re-directional mirrors, with the loss of power involved. The SF5 main components and canting procedures (alignment) of heliostat and concentrator are described, as well as the flux measurement in the focal area.
Jose Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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sintering of hdh ti powder in a Solar Furnace at plataforma Solar de almeria
Journal of Alloys and Compounds, 2017Co-Authors: Jaroslav Kovacik, Jose Rodriguez, Stefan Emmer, Inmaculada CanadasAbstract:Abstract The brand new technology for sintering of titanium was tested: For the first time, titanium powder was pressure less sintered under argon atmosphere at different temperatures and time, in 5 kW vertical axis Solar Furnace at Plataforma Solar de Almeria (PSA), Spain. The decrease of final porosity with increasing sintering temperature and time at constant heating rate is observed. The obtained results are compared with those obtained for identical green powder compacts sintered in vacuum Furnace. Final porosity below 5% was achieved and shorter sintering times were observed. Radial shrinkage of samples at Solar Furnace is almost the same as at vacuum Furnace. On the contrary axial shrinkage is 20% higher. It was proposed that this can be attributed to argon gas used during sintering and due to the different heating in Solar Furnace during sintering. Argon at lower temperature acts as a heat transfer medium and helps to distribute the heat more homogeneously into the powder compacts. At higher temperature it remains enclosed in the pores thereby increasing a bit final compact porosity when compared with vacuum Furnace. It was further showed that the contents of O, N, H in final compacts depend predominantly on their concentration in original powder. The observed increase due to technology is 300 ppm for oxygen and 80 ppm for nitrogen. Hydrogen concentration decreased significantly. Microhardness dependence on porosity of prepared samples was also investigated and microhardness of bulk Ti prepared in Solar Furnace was estimated to be 282.2 ± 28.3 HV0.5.
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temperature uniformity improvement in a Solar Furnace by indirect heating
Solar Energy, 2016Co-Authors: Fernando Costa A Oliveira, Jose Rodriguez, Inmaculada Canadas, Jorge Cruz Fernandes, Jose Galindo, L.g. RosaAbstract:Abstract The development of materials capable to work under increasingly extreme conditions requires not only higher processing temperatures but also tight control of temperature uniformity. Aiming at developing an indirect heating receiver design to be integrated in novel concentrated Solar Furnace for the thermal processing of materials under controlled heating and homogeneous temperature, graphite disc heat receiver systems with varying thickness, geometry and height from the sample holder at the bottom were tested in two types of gas environments, namely dynamic vacuum and under Ar gas flow. Results acquired were quite encouraging demonstrating feasibility of realizing temperature gradient within circa 50 °C along the height beneath the top graphite disc and the bottom sample holder.
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new psa high concentration Solar Furnace sf40
SOLARPACES 2015: International Conference on Concentrating Solar Power and Chemical Energy Systems, 2016Co-Authors: Jose Rodriguez, Inmaculada Canadas, Eduardo ZarzaAbstract:A new Solar Furnace has been designed and built at Plataforma Solar de Almeria. In this work, its main components such as heliostat, concentrator, attenuator and test table, and the method used to align them are described. Other equipment like the auxiliary systems necessary for the Solar operation, vacuum chamber and gas system are outlined too. Finally, the thermal characteristics of the focus were measured during a test campaign, where different planes along the optical axis were scanned with a radiometer, and the peak flux was obtained and is presented in the last section of this report.
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psa vertical axis Solar Furnace sf5
Energy Procedia, 2014Co-Authors: Jose Rodriguez, Inmaculada Canadas, Eduardo ZarzaAbstract:Abstract A new high-flux vertical axis Solar Furnace has been constructed and is fully operational at Plataforma Solar de Almeria (PSA). This new system is able to deliver up to 5 kW power at peak concentration ratios exceeding 6000. It has been designed to perform tests that require high radiant flux, strong gradients and very high temperatures, and will be devoted for materials treatment at high temperature, under vacuum and controlled atmosphere conditions This new Solar Furnace operates in a vertical axis, i.e. parabolic concentrator and heliostat are vertically aligned on the optical axis of the paraboloid. The main advantage of vertical axis Solar Furnaces is that the samples are deposited, without the need of any fixation, on a horizontal plane where they can be treated directly in the focus or inside crucibles, avoiding problems of loss of material by gravity in those tests in which pre-deposited powders are used, or when the treatment requires surface melting of the specimens, and preventing the use of re-directional mirrors, with the loss of power involved. The SF5 main components and canting procedures (alignment) of heliostat and concentrator are described, as well as the flux measurement in the focal area.
L.g. Rosa - One of the best experts on this subject based on the ideXlab platform.
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temperature uniformity improvement in a Solar Furnace by indirect heating
Solar Energy, 2016Co-Authors: Fernando Costa A Oliveira, Jose Rodriguez, Inmaculada Canadas, Jorge Cruz Fernandes, Jose Galindo, L.g. RosaAbstract:Abstract The development of materials capable to work under increasingly extreme conditions requires not only higher processing temperatures but also tight control of temperature uniformity. Aiming at developing an indirect heating receiver design to be integrated in novel concentrated Solar Furnace for the thermal processing of materials under controlled heating and homogeneous temperature, graphite disc heat receiver systems with varying thickness, geometry and height from the sample holder at the bottom were tested in two types of gas environments, namely dynamic vacuum and under Ar gas flow. Results acquired were quite encouraging demonstrating feasibility of realizing temperature gradient within circa 50 °C along the height beneath the top graphite disc and the bottom sample holder.
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temperature control of a Solar Furnace for material testing
International Journal of Systems Science, 2011Co-Authors: Andrade B. Da Costa, João M. Lemos, L.g. RosaAbstract:A Solar Furnace is a thermodynamic device that concentrates sun radiation in order to achieve high-temperatures at a focus, where a sample of the material to be tested is located. This article address the problem of designing a control architecture for Solar Furnaces. It is motivated by the use of a Solar Furnace as an instrument in material science research to perform two types of experimental tests. In the first type, samples are tested in high-temperature stress cycles. In these experiments it is important to control the temperature profile. The second test type is characterised by imposing a Solar radiation flux profile. On both experiment types there are strong nonlinear effects, a significant degree of parametric uncertainty and disturbances, such as Solar radiation fluctuation due to clouds and to sun's apparent movement. Although the actuator (shutter) is much faster than the thermic system, it may destabilise the overall controlled system. The contribution of this article consists in the design of a control architecture for Solar Furnaces and the application of singular perturbation methods in order to derive conditions in the form of bounds for the speed of actuator dynamics so that the closed-loop system is stable.
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An adaptive temperature control law for a Solar Furnace
2008 16th Mediterranean Conference on Control and Automation, 2008Co-Authors: Andrade B. Da Costa, João M. Lemos, E. Guillot, G. Olalde, L.g. Rosa, J. C. FernandesAbstract:This paper describes the development of an adaptive control law based on exact feedback linearization and Lyapunov adaptation of the process dynamics applied to a Solar Furnace. The controller is tested on a 6kW Solar Furnace model that represents a plant installed at the Odeillo Processes Materials and Solar Energy Laboratory (Oriental Pyrenees in the South of France). The adaptive features allow to tackle the problems posed by knowledge uncertainty about Furnace dynamics. It is concluded that the specifications related to material testing are met.
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high meta stability of tungsten sub carbide w2c formed from tungsten carbon powder mixture during eruptive heating in a Solar Furnace
International Journal of Refractory Metals & Hard Materials, 2007Co-Authors: Fernando Costa A Oliveira, L.g. Rosa, Jorge Cruz Fernandes, Jeanmarie Badie, Bernard Granier, Nobumitsu ShohojiAbstract:Abstract At around 1600 °C, stable phase in W–C binary system being in equilibrium with excess carbon is acknowledged to be mono-carbide WC. Nevertheless, during carbide formation from mixed powders of tungsten and excess carbon (C/W atom ratio: 2) in inert Ar gas environment, sub-carbide W 2 C formed besides mono-carbide WC when the heating was done extremely rapidly (instant temperature rise to 1600 °C from ambient temperature within fractions of a second) in a Solar Furnace at PROMES-CNRS in Odeillo (France) and the formed W 2 C resisted to be converted fully to WC even after 30 min heating at a temperature exceeding 2500 °C in Ar gas. Under comparatively fast heating condition (heating from ambient temperature to 1600 °C in about 1 min) realised in a Solar Furnace at PSA (Plataforma Solar de Almeria) in Tabernas (Spain), equilibrium phase WC alone formed from the similar starting material (C/W atom ratio: 1.5). Consideration is given for the formation mechanism of W 2 C under the eruptive heating condition in the Solar Furnace at PROMES-CNRS and also for the meta-stability of the formed W 2 C phase.
Manuel Berenguel - One of the best experts on this subject based on the ideXlab platform.
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implementation of feedback linearization gpc control for a Solar Furnace
Journal of Process Control, 2013Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, José Luis Guzman, Luis José YebraAbstract:Abstract In this paper the temperature control of a Solar Furnace is addressed. In particular, we propose the use of a feedback linearization generalized predictive control strategy where both the reference tracking task and the rejection of disturbances (represented by the variation of the input energy provided by the Sun, mainly because of the Solar daily cycle and passing clouds) are considered. This allows the physical and security constraints to be explicitly taken into account in the design. Simulation and experimental results show the effectiveness of the methodology and that this kind of plants can be considered as a cheap or alternative option for the material treatment and testing in the industrial context.
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IECON - A feedback linearization-based two-degree-of-freedom constrained controller strategy for a Solar Furnace
IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, Lidia RocaAbstract:A two-degree-of-freedom constrained control strategy for a Solar Furnace is proposed in this paper with the goals of attaining a minimum-time transition between two values of the temperature subject to constraints on both the saturation and slew rate level of the process input. Disturbance compensation and the model mismatches are handled by using a feedback linearization and a PID controller. Simulation results demonstrate the effectiveness of the methodology using data from the Solar Furnace of the Plataforma Solar de Almeria.
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A feedback linearization-based two-degree-of-freedom constrained controller strategy for a Solar Furnace
IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, Lidia RocaAbstract:A two-degree-of-freedom constrained control strategy for a Solar Furnace is proposed in this paper with the goals of attaining a minimum-time transition between two values of the temperature subject to constraints on both the saturation and slew rate level of the process input. Disturbance compensation and the model mismatches are handled by using a feedback linearization and a PID controller. Simulation results demonstrate the effectiveness of the methodology using data from the Solar Furnace of the Plataforma Solar de Almería.
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A feedback linearization GPC control strategy for a Solar Furnace
2012 American Control Conference (ACC), 2012Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, José Luis Guzman, Luis José YebraAbstract:This paper addresses the temperature control problem in a Solar Furnace. In particular, a feedback linearization generalized predictive control strategy is presented with the aim of improving the performance in the reference tracking and in the rejection of disturbances (represented by the variation of the input energy provided by the Sun, mainly because of passing clouds and the Solar daily cycle). Physical and security constraints are taken into account in the optimization problem. Simulation results show the effectiveness of the methodology.
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Constrained Temperature Control of a Solar Furnace
IEEE Transactions on Control Systems Technology, 2012Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, Luis José YebraAbstract:A new constrained control strategy for a Solar Furnace is proposed in this paper with the goal of attaining a minimum-time transition between two values of the temperature subject to constraints on both the saturation and slew rate level of the process input. In the case of set-point step-shape signals, the strategy basically consists in implementing a (model-based) feedforward control law with maximum positive and negative velocity phases in order to obtain a minimum-time transition with no overshoot. In the case of ramp-shape set-point signals (addressing the output slew-rate constraint), the suitable feedforward control law is obtained by also inverting the dynamics of the system. Implementation issues are discussed. Simulation and real experimental results demonstrate the effectiveness of the methodology.
Luis José Yebra - One of the best experts on this subject based on the ideXlab platform.
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implementation of feedback linearization gpc control for a Solar Furnace
Journal of Process Control, 2013Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, José Luis Guzman, Luis José YebraAbstract:Abstract In this paper the temperature control of a Solar Furnace is addressed. In particular, we propose the use of a feedback linearization generalized predictive control strategy where both the reference tracking task and the rejection of disturbances (represented by the variation of the input energy provided by the Sun, mainly because of the Solar daily cycle and passing clouds) are considered. This allows the physical and security constraints to be explicitly taken into account in the design. Simulation and experimental results show the effectiveness of the methodology and that this kind of plants can be considered as a cheap or alternative option for the material treatment and testing in the industrial context.
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A feedback linearization GPC control strategy for a Solar Furnace
2012 American Control Conference (ACC), 2012Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, José Luis Guzman, Luis José YebraAbstract:This paper addresses the temperature control problem in a Solar Furnace. In particular, a feedback linearization generalized predictive control strategy is presented with the aim of improving the performance in the reference tracking and in the rejection of disturbances (represented by the variation of the input energy provided by the Sun, mainly because of passing clouds and the Solar daily cycle). Physical and security constraints are taken into account in the optimization problem. Simulation results show the effectiveness of the methodology.
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Constrained Temperature Control of a Solar Furnace
IEEE Transactions on Control Systems Technology, 2012Co-Authors: Manuel Beschi, Antonio Visioli, Manuel Berenguel, Luis José YebraAbstract:A new constrained control strategy for a Solar Furnace is proposed in this paper with the goal of attaining a minimum-time transition between two values of the temperature subject to constraints on both the saturation and slew rate level of the process input. In the case of set-point step-shape signals, the strategy basically consists in implementing a (model-based) feedforward control law with maximum positive and negative velocity phases in order to obtain a minimum-time transition with no overshoot. In the case of ramp-shape set-point signals (addressing the output slew-rate constraint), the suitable feedforward control law is obtained by also inverting the dynamics of the system. Implementation issues are discussed. Simulation and real experimental results demonstrate the effectiveness of the methodology.
