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Electromagnetic interactions with materials: Magneto-dielectric composites design and development of a novel microwave heating device.

机译：与材料的电磁相互作用：磁电复合材料的设计和新型微波加热设备的开发。

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摘要

Electromagnetic interactions with materials dictate their performance for several applications ranging from wireless communications to energy transport. Understanding how these interactions are affected by material properties is essential for improving application performance and was the underlying theme for this work. Projects included the design and fabrication of magneto-dielectric composites and the development of a novel microwave heating device for activated carbon regeneration.;Engineered magneto-dielectric materials differ from conventional electromagnetic materials due to their enhanced magnetic properties; these materials can increase bandwidth and efficiency for a variety of technologies. However, naturally occurring magneto-dielectric materials are often non-magnetic and exhibit a large loss at frequencies greater than 1GHz. The goal of this project was to design and fabricate materials with enhanced dielectric and magnetic properties at GHz frequencies. Preliminary experimental work was focused on investigating polymer composites with spherical iron oxide nanoparticles; very large loadings of iron oxide were necessary to increase the magnetic permeability, at the cost of material integrity. Alternatively, by using frequency selective surface (FSS) layers within a polymer matrix, the design objective was successfully met. The FSS layers were designed as periodic metallic arrays, which acted as "inductive inclusions" within the polymer, collectively causing an effective susceptibility due to the interactions between inclusions and a self inductance of the inclusions, resulting in an enhanced magnetic response. The shape, dimension, and periodicity of the metallic elements of the array were variables for the final design and determined the effective properties and operational bandwidth for the composites. These materials were designed to have a permittivity and permeability greater than 2, with very low loss, from 2-5GHz. The details of the design, fabrication, and characterization of these materials will be presented in this work.;While the focus of the first project was primarily materials design, the second project involved the development of a novel application, based on the dielectric properties of the material. Activated carbon is often used as an adsorbent for applications involving removal of toxic effluents from waste streams and emissions. It has been shown that high power microwave heating is a promising alternative method to heat small volumes of activated carbon. In contrast, some applications may require heating large volumes of carbon with lower power inputs; hence, developing a novel microwave heating applicator would be important for eliminating the problem of "hot spots" found often in conventional microwave cavity heating. An applicator similar to a coaxial transmission line was designed at 2.45GHz to heat activated carbon using under 120 Watts of power; bench-top systems were constructed to analyze the efficiency of the design. An energy balance was used to model the temperature throughout the carbon in the device. Results of the device design, experimentation, and modeling will be discussed.
机译：与材料的电磁相互作用决定了它们在从无线通信到能量传输的多种应用中的性能。了解这些交互作用如何受到材料特性的影响对于提高应用程序性能至关重要，这也是这项工作的基本主题。项目包括磁电复合材料的设计和制造以及用于活性炭再生的新型微波加热装置的开发。工程磁电介质与常规电磁材料的不同之处在于其增强的磁性能；这些材料可以为多种技术增加带宽和效率。然而，天然存在的磁电介质材料通常是非磁性的，并且在大于1GHz的频率下表现出很大的损耗。该项目的目标是设计和制造在GHz频率下具有增强的介电和磁性能的材料。初步的实验工作集中在研究球形氧化铁纳米颗粒的聚合物复合材料。为了增加磁导率，以材料完整性为代价，需要非常大的氧化铁负载量。或者，通过在聚合物基质中使用频率选择表面（FSS）层，可以成功满足设计目标。 FSS层设计为周期性的金属阵列，在聚合物中充当“感应夹杂物”，由于夹杂物和夹杂物的自感之间的相互作用共同导致有效的磁化率，从而增强了磁响应。阵列金属元素的形状，尺寸和周期性是最终设计的变量，并确定了复合材料的有效性能和操作带宽。这些材料被设计为在2-5GHz范围内的介电常数和磁导率大于2，损耗非常低。这些材料的设计，制造和表征的细节将在本工作中介绍。虽然第一个项目的重点主要是材料设计，但是第二个项目则基于该材料的介电特性开发了一种新颖的应用。材料。活性炭通常用作吸附剂，用于涉及从废物流和排放物中去除有毒废水的应用。已经表明，高功率微波加热是加热少量活性炭的有前途的替代方法。相反，某些应用可能需要以较低的功率输入来加热大量的碳。因此，开发新颖的微波加热施加器对于消除常规微波腔加热中经常发现的“热点”问题将是重要的。设计了一个与同轴传输线类似的敷料器，其频率为2.45GHz，可在120瓦以下的功率下加热活性炭。构建台式系统来分析设计效率。使用能量平衡来模拟设备中整个碳的温度。将讨论设备设计，实验和建模的结果。

著录项

  • 作者

    Farhat, Susan A.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Engineering Chemical.;Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 163 p.
  • 总页数 163
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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