電 磁 性 效 應 在 對 流 流 體 中 對 微 粒 附 著 沉 積 率 之 研 究

Electromagnetic Effect on Particle Deposition Rates in a Convection Flow

戴崇全(Chung-Chuan Tai)

指導教授 ： 蔡瑞益

中原大學/工學院/機械工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300467

摘要

摘要
本文探討氣膠微粒在受到熱泳效應和電磁性效應時，對於氣膠微粒在一平板對稱流之微粒附著速度的影響。這兩種傳輸機制的交互作用，對微粒附著速度有相當重要性。本文為不可壓縮、穩態和二維層流之平板對稱流的模型，其統御方程式包括動量、能量及濃度場方程式。數值分析採用Box method與區塊消去法解其統御方程式，進而計算出氣膠微粒附著速度，微粒粒徑選擇為0.01~100μm。

同時考慮擴散效應、電磁性效應和熱泳效應時，我們發現當微粒粒徑很小時 ，微粒附著速度是受到布朗擴散和熱泳機制影響。微粒粒徑愈小、溫度差愈大，則微粒附著速度愈大，電磁性效應愈大反而讓微粒附著通量減少，因此微粒附著速度愈小；當微粒為大粒徑時(dp>1μm) ，微粒附著速度是受到熱泳機制和電磁性效應影響，電磁性效應愈大，熱泳效應減弱，電磁性效應使微粒附著通量增加，因此微粒附著速度變大。

關鍵字

電磁效應 ； 微粒附著沉積率

並列摘要

ABSTRACT
The study of particle deposition rate affected by thermophoresis and electromagnetic effect onto a plane stagnation flow are reported. The interaction between these two transport mechanisms is expected to be very important for particle deposition rate. In this study, the air flow was modeled as two dimensional, incompressible and steady-state laminar flow. The governing equations include mass, momentum, energy and concentration equations. Similarity analysis with the Box method and block elimination was used to solve these governing equations. Then we can obtain aerosol particle deposition velocity after solving these governing equations. Particle selected are in the range of 0.01~100μm .

When Brownian diffusion effect, electromagnetic effect and thermophoresis effects are considered, we can find that particle deposition rates are controlled by Brownian diffusion effect and thermophoresis effect for ultra-small particle sizes (dp>1μm). Particle sizes will decrease and temperature gradient will increase, the particle deposition rates will increase. When electromagnetic will increase, the particle flux will decrease, so particle deposition rates will decrease. Particle deposition rates are controlled by thermophoresis and electromagnetic effects for big particle sizes , particle deposition rates will increase.

並列關鍵字

particle deposition rates ； electromagnetic effect

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