添加微量液體對振動床中顆粒體分離現象的影響

The influence of adding liquids in binary mixture of granular materials on segregation mechanism

蔡宗翰(Tsung-Han Tsai)

指導教授 ： 蕭述三

國立中央大學/工學院/能源工程研究所/碩士(2008年)

摘要

本論文以實驗方法，針對顆粒體間添加微量液體後運動情形的影響，以各佔一半體積之大小顆粒加入振動床系統做為實驗設備，添加的液體包括5種黏滯度不同的矽油，借由影像處理技術對大顆粒體整體的平均高度對時間的變化作一系列的討論，其中包括穩態時間、穩態平均高度以及上升速度。
本文主要探討的控制參數為添加矽油的黏滯度和添加矽油的無因次液體含量，其中矽油的黏滯度影響液橋力的大小，而矽油的無因次液體含量與液橋的形成與否和數量的多寡有關。在本實驗中振動床內的大小顆粒體就有尺寸和密度不同所造成的分離現象，而液橋力則會阻礙顆粒體的運動，在這些力的作用下產生不同的分離結果。
本實驗中大顆粒體穩態平均高度及平均上升速度，會呈現黏滯度越高則越低，無因次液體含量越高也是一樣結果，至於達到穩態時間和分離率則相反，隨著黏滯度和無因次液體含量增加而減小。

關鍵字

分離 ； 振動床 ； 顆粒床 ； 液橋力 ； 黏滯度 ； 液體含量

並列摘要

The influence of adding liquids in binary mixture of granular materials on segregation mechanism was studied in this paper. The experiment facility of a vertical vibrated bed was used in this study. The granular materials consist of a binary mixture with the same volume fraction of small/heavy and large/light particles. The liquids added in the granular materials are silicon oils with five different viscosities. The ensemble average height of large particles changes with time.
This controlled parameters include viscosity and dimensionless liquid content of the adding silicon oils. The liquid bridge force was greater with the increasing viscosity of the silicon oil. The increasing dimensionless liquid content of the liquid results in and stronger liquid bridges causing the higher liquid bridge force in the system. In this study, the particles in the vibrated bed display the segregation phenomenon due to the different size and density of particles. The particle motions are weaker in the system with adding more viscous or higher amount of liquid due to the stronger liquid bridge force. It results in the reduction of the segregation.
The results show that the dimensionless average height of large particles and average rising velocity decrease with the increase of the viscosity and dimensionless liquid content of adding silicone oil. However segregation and the time for reaching steady state in the system decreases with the increase of the viscosity and dimensionless liquid content of adding silicone oil.

並列關鍵字

granular bed ； liquid bridge force ； viscosity ； liquid content ； vibrated bed ； segregation

參考文獻

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