【摘要】：工業(yè)生產(chǎn)中產(chǎn)生的粉塵顆粒會對環(huán)境和人體健康造成危害，隨著國家對污染物排放標(biāo)準(zhǔn)的逐漸提高以及人們環(huán)保意識的增強，對空氣中的微細(xì)顆粒物進(jìn)行有效的過濾顯得至關(guān)重要。纖維過濾材料對顆粒物的過濾能達(dá)到國家標(biāo)準(zhǔn)的要求，因此對其過濾性能進(jìn)行研究可以為過濾介質(zhì)的優(yōu)化提供依據(jù)。 本文通過掃描電鏡成像（Scanning Electron Microscopy，SEM）獲得纖維過濾介質(zhì)的二維截面圖像，利用Matlab對所得圖像進(jìn)行處理，編寫重建三維過濾介質(zhì)所需的程序，并與Gambit結(jié)合，最終生成以實際過濾介質(zhì)為基礎(chǔ)的三維模型；通過改變模型的結(jié)構(gòu)參數(shù)，包括纖維直徑df、纖維的偏離距離L和前后延伸長度H三個參數(shù)，利用響應(yīng)曲面法分析結(jié)構(gòu)參數(shù)和迎面風(fēng)速對過濾介質(zhì)氣相場、固體體積分?jǐn)?shù)（Solid Volume Fraction, SVF）和壓力損失的影響，并與經(jīng)驗?zāi)Ｐ偷慕Y(jié)果進(jìn)行比較；通過CFD-DEM耦合技術(shù)，模擬纖維過濾介質(zhì)內(nèi)部的氣-固兩相流動，研究纖維與顆粒的特性對顆粒沉積和團(tuán)聚的影響，改變過濾介質(zhì)的結(jié)構(gòu)參數(shù)以分析其對介質(zhì)過濾特性（包括壓力損失和過濾效率）的影響，結(jié)果表明： （1）本文通過Matlab與Gambit結(jié)合重建出的三維過濾介質(zhì)模型是以實際過濾介質(zhì)的二維圖像為基礎(chǔ)，重建的模型與實際的過濾介質(zhì)具有很大的關(guān)聯(lián)性，對這些模型進(jìn)行研究為推測實際過濾介質(zhì)的過濾性能提供了依據(jù)。 （2）纖維直徑是影響過濾介質(zhì)SVF和氣相場壓力損失的顯著因素，兩者都隨著纖維直徑的增大而增大。纖維的偏離距離L和前后距離H對SVF的影響很小，但壓力損失隨L和H的增大先增大后減小，在兩者為中水平時達(dá)到最大值。 （3）纖維過濾介質(zhì)內(nèi)部的氣相流場呈現(xiàn)不均勻性。氣相場壓力損失隨著SVF和迎面風(fēng)速的增大而增大，SVF相同時，不同結(jié)構(gòu)參數(shù)的過濾介質(zhì)壓力損失存在差別，表明過濾介質(zhì)的壓力損失與纖維的排列方式有關(guān)。此外，壓力損失的模擬值與Davies實驗關(guān)聯(lián)式吻合的較好，誤差小于5%，說明本文的纖維過濾介質(zhì)數(shù)值計算模型是合理的，同時進(jìn)行的過濾介質(zhì)內(nèi)部氣相流場的數(shù)值模擬也是可信的。 （4）利用CFD-DEM耦合方法對纖維過濾介質(zhì)內(nèi)部的氣-固兩相流動進(jìn)行數(shù)值模擬，然后研究過濾介質(zhì)結(jié)構(gòu)參數(shù)的變化對其壓力損失和過濾效率以及顆粒沉積和團(tuán)聚的影響，過濾介質(zhì)效率的模擬值與經(jīng)驗關(guān)聯(lián)式計算值總體趨勢一致，表明本文的模型是合理的。通過顆粒在纖維上沉積與團(tuán)聚的模擬圖與實驗觀測圖對比可知，利用CFD-DEM研究顆粒在纖維介質(zhì)表面沉積與團(tuán)聚是可行的。 （5）在介質(zhì)過濾階段，顆粒在纖維介質(zhì)表面沉積的質(zhì)量隨著過濾時間的增加而增加，當(dāng)纖維偏離距離L和延伸長度H不變，纖維直徑df增大時，表面過濾的貢獻(xiàn)較大。 （6）相對于氣相流場，不同工況下纖維過濾介質(zhì)在過濾顆粒時的壓力損失均增加，且呈現(xiàn)指數(shù)增長的趨勢，表明顆粒的沉積改變了過濾介質(zhì)內(nèi)部的孔隙率，從而對介質(zhì)的壓力損失產(chǎn)生影響。纖維直徑df是影響過濾介質(zhì)總壓力損失的主要因素，，隨著df的增加，總壓力損失增大。纖維偏離距離L和延伸長度H變化時，纖維的排列方式發(fā)生了變化，過濾介質(zhì)的總壓力損失隨具體的工況而定�？傮w而言，纖維分布越密集，介質(zhì)的總壓力損失越大。纖維過濾介質(zhì)的過濾效率隨著纖維偏離距離L的增加而減小，纖維延伸長度H的變化對效率基本無影響。
[Abstract]:The dust particles produced in the industrial production can be harmful to the environment and the human health, and the effective filtration of the fine particles in the air is of great importance as the country's gradual improvement of the emission standard of the pollutants and the enhancement of the environmental awareness of the people. The filtering performance of the fiber filter material can meet the requirements of the national standard, so the filtering performance of the fiber filter material can provide the basis for the optimization of the filter medium. In this paper, two-dimensional section images of fiber filter media were obtained by scanning electron microscopy (SEM). The obtained images were processed by using Matlab. The program needed to reconstruct the three-dimensional filter media was written and combined with Gamit. The three-dimensional model based on the actual filter media was finally generated. By changing the structural parameters of the model, including the fiber diameter df, the deviation distance L of the fiber and the front and rear extension length H, the solid volume fraction (SVF) and the pressure loss are analyzed by using the response surface method to analyze the structural parameters and the head-on wind speed. In response to the results of the empirical model, the gas-solid two-phase flow in the fiber filtration media was simulated by the CFD-DEM coupling technique, and the properties of the fibers and the particles were studied. In response, the structural parameters of the filter medium are changed to analyze its effect on the filter characteristics of the medium, including pressure loss and filtration efficiency, and the results table (1) The three-dimensional filter media model reconstructed from the combination of Matlab and Gamit is the two-dimensional image of the actual filter media. On the basis of which, the reconstructed model has a great relevance to the actual filter media, and the research of these models is to estimate the filtering performance of the actual filter media. (2) The fiber diameter is a significant factor that affects the pressure loss of the SVF and gas phase fields of the filter medium, both of which follow the diameter of the fiber The deviation distance L of the fiber and the front-to-back distance H have little effect on the SVF, but the pressure loss decreases with the increase of L and H, the maximum value is reached. (3) the gas phase flow inside the fiber filter medium If the pressure loss of the gas phase increases with the increase of the SVF and the head-on wind speed, the pressure loss of the filter media of different structural parameters is different when the SVF is the same, indicating the pressure loss and the fiber of the filter medium. In addition, the simulated value of pressure loss is well matched with Davies' experimental correlation formula, and the error is less than 5%. The numerical calculation model of the fiber filter media in this paper is reasonable, and the numerical value of the gas-phase flow field inside the filtration media The simulation is also credible. (4) The gas-solid two-phase flow in the fiber filter media is numerically simulated by means of the CFD-DEM coupling method, and the pressure loss and the filtration efficiency of the filter media are studied. The effect of particle deposition and agglomeration is that the simulation value of the efficiency of the filter medium is consistent with the general trend of the empirical correlation formula. The model of this paper is reasonable. Through the comparison between the simulation of the deposition and the agglomeration of the particles on the fiber and the experimental observation, the research of the particle on the surface of the fiber medium with the CFD-DEM the deposition and agglomeration are feasible. (5) the mass of the particles on the surface of the fiber medium increases with the increase of the filtration time during the media filtration stage, the fiber diameter df increases when the fiber deviates from the distance l and the extension length h, On the other hand, the contribution of surface filtration is large. (6) In contrast to the gas-phase flow field, the pressure loss of the fiber filter media in the filter particles is increased, and the trend of exponential growth is presented, indicating that the deposition of the particles changes the porosity inside the filter medium, and the fiber diameter df is the main factor that affects the total pressure loss of the filter media, the increase in df increases the total pressure loss. the arrangement of the fibers changes when the distance l and the extension length h change, and the filter media The total pressure loss varies with the specific operating conditions. Overall, the more fiber distribution the larger the total pressure loss of the medium, the larger the filtration efficiency of the fiber filter media decreases with the increase of the fiber offset distance l, the fiber extension length,
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU834

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