本文選題：碳納米管　切入點(diǎn)：計(jì)算流體動力學(xué)　出處：《南昌航空大學(xué)》2015年碩士論文

【摘要】：碳納米管因其具備的獨(dú)特電子、氣體吸附以及機(jī)械性能,因此被應(yīng)用到許多領(lǐng)域。目前,大規(guī)模生產(chǎn)碳納米管主要采用化學(xué)氣相沉積法(CVD法)。然而氣相沉積過程復(fù)雜,對沉積速率影響的因素較多,利用傳統(tǒng)實(shí)驗(yàn)方法優(yōu)化價(jià)格昂貴且費(fèi)時(shí)。通過計(jì)算機(jī)對CVD法制備碳納米管過程進(jìn)行模擬,既可以縮短優(yōu)化工藝參數(shù)的周期、而且還能降低成本,并且對沉積過程有更深層次的了解,用實(shí)驗(yàn)研究沉積過程有很大的幫助。本文通過耦合流體流動、傳熱傳質(zhì)、化學(xué)反應(yīng)等物理模型,建立了化學(xué)氣相沉積法制備碳納米管過程的二維模型。采用計(jì)算流體力學(xué)(CFD)方法對生產(chǎn)碳納米管初期碳源的獲取過程進(jìn)行分析。探討了不同反應(yīng)條件下對碳沉積率的影響以及噴嘴式CVD反應(yīng)器內(nèi)部結(jié)構(gòu)組成對反應(yīng)過程的影響。研究內(nèi)容及結(jié)果主要如下:(1)針對CVD反應(yīng)器內(nèi)部進(jìn)口氣體速率的改變對反應(yīng)過程中碳沉積率影響進(jìn)行分析,結(jié)果表明:隨著進(jìn)口速率的增大,各個(gè)階段的碳沉積率增長速率各不相同,速度范圍在0.5m/s-5.0m/s上的碳沉積率增長速率是最高的,而當(dāng)速度大于5.0m/s,碳沉積率增長速率則趨于平緩;(2)針對CVD反應(yīng)器內(nèi)部反應(yīng)溫度的改變對反應(yīng)過程中碳沉積率影響進(jìn)行分析,結(jié)果表明:根據(jù)不同溫度下碳沉積率變化規(guī)律并結(jié)合碳納米管在不同溫度下的轉(zhuǎn)化率,推斷出最佳反應(yīng)溫度是由該溫度下碳沉積量與該溫度下碳納米管轉(zhuǎn)化率兩者的乘積所決定的;(3)針對CVD反應(yīng)器內(nèi)部氣源供給量以及進(jìn)口氣體溫度的改變對反應(yīng)過程中碳沉積率影響進(jìn)行分析,結(jié)果表明:隨著氣源供給量以及進(jìn)氣溫度的增大,碳沉積率均隨之而升高,并發(fā)現(xiàn)各個(gè)階段的碳沉積率增長速率近似相同,通過曲線擬合獲得了氣源供給量—碳沉積率以及進(jìn)口氣體溫度—碳沉積率兩者之間的函數(shù)關(guān)系式。(4)針對噴嘴式CVD反應(yīng)器結(jié)構(gòu)的內(nèi)部組成對碳沉積率的影響進(jìn)行分析,將內(nèi)部結(jié)構(gòu)拆分為四種結(jié)構(gòu),觀察各結(jié)構(gòu)之間的有無對反應(yīng)過程的影響。結(jié)果表明:當(dāng)反應(yīng)結(jié)構(gòu)沒有噴嘴時(shí),增加芯片與否,對于物種分布的影響不大;當(dāng)反應(yīng)結(jié)構(gòu)有噴嘴時(shí),芯片對物種質(zhì)量分布會產(chǎn)生一定的影響,無芯片將會降低碳沉積效率;通過比較四種不同結(jié)構(gòu)反應(yīng)器的碳沉積速率分布曲線圖得知,在相同的外界條件下,比較四種結(jié)構(gòu)的沉積率曲線圖,證實(shí)了噴嘴式CVD反應(yīng)器內(nèi)部結(jié)構(gòu)的組成有利于促進(jìn)碳沉積率的增加。并且探討了芯片的高度對碳沉積率變化的影響,發(fā)現(xiàn)當(dāng)芯片高度與進(jìn)口直徑比值小于1/2時(shí),碳沉積率隨著芯片高度的增大呈現(xiàn)出明顯的遞增趨勢;而當(dāng)芯片高度與進(jìn)口直徑比值大于1/2時(shí),碳沉積率隨著芯片高度的增大遞增趨勢不明顯。
[Abstract]:Carbon nanotubes (CNTs) have been applied in many fields because of their unique electronic, gas adsorption and mechanical properties.At present, carbon nanotubes are produced by chemical vapor deposition (CVD).However, the process of Vapor deposition is complicated and the factors affecting the deposition rate are many. It is expensive and time-consuming to optimize by traditional experimental methods.The process of preparing carbon nanotubes by CVD method is simulated by computer, which can not only shorten the period of optimizing process parameters, but also reduce the cost, and has a deeper understanding of the deposition process. It is helpful to study the deposition process by experiment.Based on coupled fluid flow, heat and mass transfer, chemical reaction and other physical models, a two-dimensional model for the preparation of carbon nanotubes by chemical vapor deposition has been established in this paper.Computational fluid dynamics (CFD) method was used to analyze the acquisition process of carbon source in the initial production of carbon nanotubes.The influence of different reaction conditions on the carbon deposition rate and the influence of the internal structure of the nozzle type CVD reactor on the reaction process were discussed.The main contents and results are as follows: (1) the influence of the inlet gas rate on the carbon deposition rate in the CVD reactor is analyzed. The results show that: with the increase of the inlet rate,The growth rate of carbon deposition rate varies from stage to stage, and the growth rate of carbon deposition rate in the range of 0.5m/s-5.0m/s is the highest.When the velocity is greater than 5.0 m / s, the increasing rate of carbon deposition rate tends to be flat.) the effect of reaction temperature on carbon deposition rate in CVD reactor is analyzed.The results show that according to the change of carbon deposition rate at different temperatures and the conversion of carbon nanotubes at different temperatures,It is inferred that the optimum reaction temperature is determined by the product of carbon deposition amount and carbon nanotube conversion at that temperature.The effect of carbon deposition rate was analyzed,The results show that the carbon deposition rate increases with the increase of gas supply and inlet air temperature, and it is found that the growth rate of carbon deposition rate is approximately the same at each stage.By curve fitting, the functional relationship between the feed ratio of gas source and the ratio of carbon deposition and the temperature of inlet gas and the rate of carbon deposition are obtained. The influence of the internal composition of nozzle type CVD reactor on the carbon deposition rate is analyzed.The internal structure was divided into four structures and the effect of each structure on the reaction process was observed.The results show that when there is no nozzle in the reaction structure, the increase of the chip has little effect on the species distribution, and when there is a nozzle in the reaction structure, the chip will have a certain effect on the species quality distribution, and the carbon deposition efficiency will be reduced without the chip.By comparing the carbon deposition rate distribution curves of four kinds of reactors with different structures, it is found that under the same external conditions, the deposition rate curves of the four structures are compared.It is proved that the composition of the internal structure of the nozzle CVD reactor is beneficial to the increase of carbon deposition rate.The influence of chip height on carbon deposition rate is discussed. It is found that when the ratio of chip height to inlet diameter is less than 1 / 2, the carbon deposition rate increases obviously with the increase of chip height.However, when the ratio of chip height to inlet diameter is greater than 1 / 2, the increasing trend of carbon deposition rate is not obvious with the increase of chip height.
【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ127.11;TB383.1

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 邱介山，，郭樹才;碳沉積法制空分用炭分子篩的研究[J];大連理工大學(xué)學(xué)報(bào);1995年06期

2 常煥發(fā);;錳鐵高爐爐底石墨碳沉積問題淺析[J];煉鐵;1990年02期

3 王利生;張宏雷;毋俊生;E．G．Rakov;;基于化學(xué)傳遞反應(yīng)模擬甲烷和乙炔燃焰中碳沉積的條件[J];計(jì)算機(jī)與應(yīng)用化學(xué);2006年03期

4 于建國;王玉璋;翁史烈;;煤氣組分對固體氧化物燃料電池碳沉積的影響[J];無機(jī)材料學(xué)報(bào);2011年11期

5 王安杰;郭樹才;;粘結(jié)性煤的碳分子篩制備及性能研究[J];煤化工;1989年02期

6 閻鵬勛,陳發(fā)貴;離子注入過程中表面的碳沉積[J];核技術(shù);1992年12期

7 倪紅衛(wèi),茅洪祥,馬國軍,蒼大強(qiáng),姜鈞普;用H_2-CH_4氣制備碳化鐵過程中碳沉積研究[J];鋼鐵研究;1999年04期

8 王振余，郭樹才;熱縮聚煤瀝青壓型制備分子篩炭膜（Ⅱ）──液相碳沉積法制備分子篩炭膜[J];炭素技術(shù);1996年03期

9 L.J.Velenyi;葛世培;;用于催化循環(huán)過程的碳反應(yīng)性和表征[J];新型碳材料;1987年02期

10 ;[J];;年期

相關(guān)會議論文 前1條

1 葉彬;楊明理;李象遠(yuǎn);;乙炔碳沉積的分子動力學(xué)模擬[A];中國化學(xué)會第29屆學(xué)術(shù)年會摘要集——第41分會：燃料與燃燒化學(xué)[C];2014年

相關(guān)碩士學(xué)位論文 前2條

1 閔偉;化學(xué)氣相沉積制備碳納米管的數(shù)值模擬[D];南昌航空大學(xué);2015年

2 吳鎧;水稻根際碳沉積的計(jì)量分析[D];湖南農(nóng)業(yè)大學(xué);2014年

本文編號：1713476