Abstract

In present studies, dielectric properties of eggshell powder were determined at microwave frequencies 2.45 and 5.8 GHz by varying temperature and moisture content in the range 15–75 °C and 0.5–8% (wet-basis) respectively, using cavity perturbation technique. Values of dielectric constant (ε′) and loss factor (ε″) increase with temperature and moisture content at both of these frequencies but ε′ is higher at 2.45 GHz than 5.8 GHz whereas ε″ shows opposite trend. The calculated penetration depths of microwaves are more at 2.45 GHz than 5.8 GHz and it decreases with increase in temperature as well as moisture content. The determined data of ε′ and ε″ were used to generate the third order regression equations with high correlation coefficients (R² > 0.95). These findings are useful for modelling and designing the microwave applicator for heat treatment to eggshell powder. Additionally, X-ray diffraction spectra was also recorded.

摘要

在目前的研究中，蛋壳粉的介电性能是在 2.45 和 5.8 GHz 的微波频率下分别通过在 15-75 °C 和 0.5-8%（湿基）范围内改变温度和水分含量，使用腔扰动技术来确定的。在这两个频率下，介电常数 ( ε ') 和损耗因子 ( ε ') 的值随着温度和水分含量的增加而增加，但ε ' 在 2.45 GHz 时高于 5.8 GHz，而ε ' 显示相反的趋势。计算出的微波穿透深度在 2.45 GHz 时比在 5.8 GHz 时更大，并且随着温度和水分含量的增加而减小。ε ′和ε的确定数据''用于生成具有高相关系数（ R ² > 0.95）的三阶回归方程。这些发现对于建模和设计用于对蛋壳粉进行热处理的微波施加器非常有用。此外，还记录了 X 射线衍射光谱。