本文關(guān)鍵詞：亞微米微粒的捕集技術(shù)研究　出處：《中國計量大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 亞微米微粒 靜電捕集 顆粒荷電 捕集效率

【摘要】：亞微米微粒因具有復(fù)雜的運(yùn)動特性以及荷電特性,使對其捕集造成極大困難,因此有必要對此粒徑段顆粒的捕集技術(shù)及其效果進(jìn)行研究。本文在對亞微米微粒的靜電捕集理論研究的基礎(chǔ)上,采用實(shí)驗(yàn)和數(shù)值模擬兩種方法研究靜電捕集技術(shù)對亞微米微粒的捕集效果并分析影響捕集效率的各種參數(shù),并對其捕集前后的粒徑譜進(jìn)行對比分析。實(shí)驗(yàn)設(shè)計搭建靜電捕集裝置平臺,采用快速粒徑譜儀和質(zhì)量濃度測量儀測量顆粒捕集前后的顆粒數(shù)量濃度和質(zhì)量濃度,分析正負(fù)離子荷電、極板層數(shù)、背景濃度和電壓對顆粒捕集效率的影響,以及粒徑譜的變化特征。研究表明:負(fù)離子荷電后的數(shù)量和質(zhì)量捕集效果都比正離子荷電后的捕集效果要好;增加電極板的層數(shù)會明顯提高顆粒的捕集效率,但其效率的增加不會成倍的增加,且其增加量逐漸減小;顆粒的捕集效率隨著電壓的增大先增大后減小,每個極板間距都有一個最佳電壓;顆粒的捕集效率與其背景濃度成指數(shù)變化關(guān)系,其捕集效率在未到達(dá)90%之前隨著背景濃度增大而快速增加;捕集前的粒徑譜成單峰分布,峰值在100nm到200nm之前,捕集后的粒徑譜也成單峰分布,但其峰值處較捕集前平滑許多。數(shù)值模擬采用Fluent軟件對顆粒軌跡進(jìn)行仿真計算,應(yīng)用udf編程添加電場力的作用,模擬研究電壓和極板間距對顆粒在捕集通道內(nèi)的運(yùn)動軌跡的影響。模擬顯示,在其它條件相同的情況下,極板間電壓越大,顆粒的運(yùn)動軌跡的偏移量就越大;極板間距越大,顆粒軌跡的偏移量越小;在同一極板間距和同一電壓下,顆粒捕集裝置對顆粒的偏移量和捕集效率隨著粒徑的增大成增大的趨勢,但粒徑在200nm時其捕集效率增加較快,粒徑在500nm時,其捕集效率會有所下降。原因是在200nm到500nm之間的顆粒同時受擴(kuò)散荷電和場致荷電作用并飽和荷電,因此在此段粒徑段的荷電量較大。
[Abstract]:It is very difficult for submicron particles to trap because of their complex motion and charge characteristics. Therefore, it is necessary to study the trapping technology and its effect of this particle size segment. This paper is based on the electrostatic trapping theory of submicron particles. The effect of electrostatic trapping on submicron particles was studied by means of experiment and numerical simulation, and various parameters affecting the trapping efficiency were analyzed. And the particle size spectrum before and after trapping was compared and analyzed. The electrostatic trapping device platform was designed and built. The quantity and concentration of particles before and after capture were measured by fast particle size spectrometer and mass concentration measuring instrument. The effects of positive and negative ion charge, plate number, background concentration and voltage on particle trapping efficiency were analyzed. The results show that the quantity and mass trapping effect of negative ion charged is better than that of positive ion charge. Increasing the layer number of the electrode plate can obviously improve the trapping efficiency of particles, but the increase of the efficiency will not increase by many times, and the increasing amount will gradually decrease. The particle trapping efficiency increases first and then decreases with the increase of voltage, and each plate spacing has an optimum voltage. The trapping efficiency of particles is exponentially related to the background concentration, and the trapping efficiency increases rapidly with the increase of background concentration before reaching 90%. The particle size spectrum before capture is a single peak distribution, the peak value is before 100nm to 200nm, and the particle size spectrum after trapping is also a single peak distribution. However, the peak value is much smoother than that before trapping. Fluent software is used to simulate the particle trajectory, and the effect of electric field force is added by udf programming. The effects of voltage and plate spacing on the trajectory of particles in the trapping channel are studied. The simulation results show that the larger the voltage between the poles is, the greater the migration of the particle trajectory is under the same conditions. The larger the polar plate spacing, the smaller the migration of particle trajectories. Under the same plate spacing and same voltage, the migration and the capture efficiency of the particle trapping device increase with the increase of the particle size, but the trapping efficiency increases faster when the particle size is 200 nm. When the particle size is 500nm, the trapping efficiency decreases, because the particles between 200nm and 500nm are simultaneously charged by diffusion charge and field charge and saturated charge. Therefore, the charge at this stage of particle size is larger.
【學(xué)位授予單位】：中國計量大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：X701.2;X513

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