粒狀農產品介電常數與密度關係之有限元素分析

Finite Element Analysis of the Density Dependence of Dielectric Constants of Particulate Agricultural Materials

朱元南(Yuan-Nan Chu) ； 李允中(Yeun-Chung Lee)

《農業機械學刊》 1卷4期 (1992/12) Pp. 1-9

https://doi.org/10.30062/JAM.199212.0001

摘要

粒狀農産品的介電常數會受到其密度的變化而改變。本文的目的爲利用有限元素法模擬不同密度的粒狀農産品，經由分析靜電場中粒狀顆粒的總電位能，求得其等效介電常數，以分析密度與介電常數的關係。顆粒的模擬採用球狀與碟狀兩種模型以比較其適用性。分析結果與文獻中的實驗數據相當符合。密度與介電常數的關係可用二次方程式表示。介電常數的二次及三次方根與密度成線性關係。碟狀模型可用於預測粉狀或小顆粒農産品之介電常數與密度之關係。利用碟狀模型對麵粉介電常數的分析結果之誤差小於1.3%。

關鍵字

介電常數 ； 有限元素分析 ； 粒狀物質 ； 密度

並列摘要

The purpose of this study was to model the effects of density on the dielectric constants of particulate agricultural materials using finite element analysis. The dielectric constant is calculated from the total potential energy of the material in a static electric field. A disk model and a sphere model simulating the particulate material were developed. Analyzed results agree with the experimental data from the literature. The relationship between the dielectric constant and density of the material may be described by quadratic equations. The square root and the cubic root of the dielectric constants are linearly related to the volume ratios. The disk model is more suited for, predicting the dielectric constants of powders or fine particles at varying densities. The error of prediction for the dielectric constant of flour using the disk model is less than 1.3%.

並列關鍵字

Dielectric constant ； Finite element analysis ； Particulate materials ； Density