Dielectric Properties of Biomass/Biochar Mixtures at Microwave Frequencies
Dielectric Properties of Biomass/Biochar Mixtures at Microwave Frequencies
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DOI：
10.3390/en10040502
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发表时间：
2017-04-01
期刊：
影响因子：
3.2
通讯作者：
Boldor, Dorin
中科院分区：
文献类型：
--
作者：
Ellison, Candice;McKeown, Murat Sean;Boldor, Dorin
材料的介电特性对于理解它们对微波的响应是重要的。碳质材料被认为是良好的微波吸收剂，并且可以与干生物质（其在其他方面是低损耗材料）混合，以提高生物质原料的加热效率。在这项研究中，粉碎的生物质和生物炭混合物的介电性能，在室温下从0.5 GHz到20 GHz。采用开路同轴线介电探针和矢量网络分析仪测量了材料的介电常数和介质损耗因子。结果表明，介电常数和介电损耗随生物炭含量的增加呈二次曲线增加。在对生物炭的测量中，在8GHz下观察到强介电弛豫，如在该频率下介电损耗因子的峰值所指示的。发现生物炭是良好的微波吸收剂，并且生物质和生物炭的混合物可用于提高用于生物质原料的高温微波处理的微波加热速率。这些数据可用于设计，放大和模拟生物质，生物炭，及其混合物的微波加热过程。
Material dielectric properties are important for understanding their response to microwaves. Carbonaceous materials are considered good microwave absorbers and can be mixed with dry biomasses, which are otherwise low-loss materials, to improve the heating efficiency of biomass feedstocks. In this study, dielectric properties of pulverized biomass and biochar mixtures are presented from 0.5 GHz to 20 GHz at room temperature. An open-ended coaxial-line dielectric probe and vector network analyzer were used to measure dielectric constant and dielectric loss factor. Results show a quadratic increase of dielectric constant and dielectric loss with increasing biochar content. In measurements on biochar, a strong dielectric relaxation is observed at 8 GHz as indicated by a peak in dielectric loss factor at that frequency. Biochar is found to be a good microwave absorber and mixtures of biomass and biochar can be utilized to increase microwave heating rates for high temperature microwave processing of biomass feedstocks. These data can be utilized for design, scale-up and simulation of microwave heating processes of biomass, biochar, and their mixtures.