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Session: TH4A3:30 PM Thursday, May 27, 2010 Room: 205AB |
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Session: TH4A | Microwave High Power Processes: Modeling and Applications |
Chair: | Malgorzata Celuch, Warsaw University of Technology |
Co-Chair: | Vadim Yakovlev, Worcester Polytechnic Institute |
Abstract: | Modeling techniques for microwave power processes in domestic ovens and industrial systems are developed. Advanced multiphysics FDTD algorithms and modeling-based nondestructive evaluation schemes are discussed. Design of industrial scale systems for microwave processing of materials is presented. Examples of applications include dielectric heating for sintering and purification of contaminated drill cuttings. Innovative in-situ monitoring of the microwave sintering process is described. |
| | TH4A-1 | Microwave Antenna Array for High Temperature Materials Processing | 3:30 PM-3:50 PM | T. Gerdes1, H. Park2, A. Rosin1, A. Schmidt3, M. A. Willert-Porada1, 1University of Bayreuth, Bayreuth, Germany, 2Centre of New Materials, Bayreuth, Germany, 3InVerTec eV., Bayreuth, Germany |
(1544) | Industrial scale high temperature microwave processing of materials, like e.g., dielectric heating for sintering or heat treatment of powder metals and ceramics has not been successful yet, mainly because of lack of suitable equipment. The paper presents results of antenna development aiming at 2.45 Ghz microwave transmission into hot processing chambers, with minimum heat loss because only minor cooling of windows or transmission lines is required. High power microwave coupling is enabled by an array of high temperature resistant rod antennas. The design is performed in two steps: first simulation (FDTD) and experimental validation is done for a single antenna, than the results are transferred into the design of a 6 antenna array. This antenna array is capable of transmitting up to 36 kW 2.45 GHz radiation into a 1m³ volume process chamber at temperatures up to 1500°C. The E-H-field distribution and the limitations of material selection for the antenna array are discussed. | | |
TH4A-2 | A Modeling-Based Technique for Nondestructive Evaluation of Metal Powders Undergoing Microwave Sintering | 3:50 PM-4:10 PM | A. V. Brovko1, E. K. Murphy2, V. V. Yakovlev3, 1Saratov State Technical University, Saratov, Russian Federation, 2Rensselaer Polytechnic Institute, Troy, United States, 3Worcester Polytechnic Institute, Worcester, United States |
(1684) | A microwave imaging technique is proposed for reconstruction of geometrical parameters (a spatial position and a radius) of a metal sphere emerging inside the sample of metal powder in the course of microwave sintering. The technique relies on a numerical inversion realized with an artificial neural network backed by data on S-parameters obtained from FDTD simulation and measurement. Numerical experiments are performed in the frequency range from 2 to 3 GHz for a cylindrical sample of iron powder in a two-port waveguide system. The results show that the spheres of not less than 2 mm radius are reconstructed with the average errors of 0.2-2.2%. | | |
TH4A-3 | Latest Developments in the Microwave Processing of Oil Contaminated Drill Cuttings | 4:10 PM-4:30 PM | S. Kingman, J. Robinson, C. Antonio, I. Pereira, University of Nottingham, Nottingham, United Kingdom |
(1535) | The paper presents very recent results from a novel continuous, pilot scale microwave treatment process for the continuous treatment of oil contaminated drill cuttings. The requirements of a commercial scale system are outlined, and the necessary scale-up challenges are highlighted. The process has been developed for the remediation of contaminated drill cuttings at source, i.e. on offshore oil platforms of remote installations, with minimal demand for utilities and a very small footprint. The process separates the contaminant oil from the drill cuttings, leading to an inert solid material and an oil product that can potentially be reused within the mud system. The process can remediate the cuttings to below 0.1% oil. The unique heating mechanisms obtained using microwave treatment mean that the recovered oil is not degraded as can be the case with conventional thermal desorption or mechanical processes. The energy requirements are of the order of 100 kWh per tonne of cuttings. | | |
TH4A-4 | Influence of the magnetron operating frequency on the results of microwave heating | 4:30 PM-4:50 PM | M. Soltysiak1, U. Erle2, M. Celuch3, 1QWED, Warsaw, Poland, 2Nestle, Solon, United States, 3Warsaw University of Technology, Warsaw, Poland |
(1497) | In typical simulations of heating processes in household microwave ovens it is assumed that the frequency of the magnetron stays constant at its nominal value. In reality, due to manufacturing variations, load parameters, and the magnetron temperature, frequency differences or jumps of 50 MHz may occur. This publication shows coupled electromagnetic and thermal simulations of microwave heating phenomena in household microwave ovens. Several analyses are performed for a static load at various frequencies in order to assess possible effects of frequency changes on the heating patterns. A novel FDTD regime with moving loads and frequency tuning is then applied to demonstrate that the load rotation typically implemented in domestic microwave ovens largely equalises the patterns at different frequencies. Both, the total absorbed power and the power distribution in the load are studied. | | |
TH4A-5 | Microwave-induced electromigration in multicomponent metallic alloys | 4:50 PM-5:10 PM | S. Vaucher1, L. Bernau3, M. Stir1, K. Ishizaki1, J. Catala-Civera2, R. Nicula1, 1Empa- Swiss Federal Laboratories for Materials Testing and Research, Thun, Switzerland, 2Polytechnic University of Valencia, Valencia, Spain, 3Empa- Swiss Federal Laboratories for Materials Testing and Research, Thun, Switzerland |
(1306) | The crystallization of amorphous FeCoCuZrAlSiB alloy ribbons during microwave heating was investigated in situ using time-resolved X-ray powder diffraction. The formation of the nanocrystalline α-(Fe,Co)(SiAl) phase during the primary crystallization stage is followed by the crystallization of the residual glassy matrix. Scanning electron microscopy analysis after microwave exposure reveals the formation of nanosized hillocks evenly distributed over the ribbon surfaces. Local composition analysis by energy-dispersive spectroscopy shows that the surface clusters are enriched in Cu and Al. The occurrence of this typical electromigration effect imposes a restriction on the exposure of metallic ribbons to microwave fields and reinforces the need for prior characterization in particular by in situ time-resolved techniques. | | |
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