两种典型醇类燃料燃烧的实验和模型研究

发布时间：2018-06-14 19:50

本文选题：甲醇 + 2-甲基-1-丁醇　；参考：《中国科学技术大学》2016年硕士论文

【摘要】：能源是国民经济的动力和命脉。化石燃料的燃烧提供了全球85%和我国近90%的一次能源需求。现如今化石燃料的急剧消耗不仅带来了前所未有的能源危机,还酿成了环境污染的恶果,时刻威胁着环境安全和人类健康。生物醇类,可以用作汽油的添加剂或者替代燃料,一方面可以减缓人类对化石燃料的过分依赖,另一方面醇类燃料中的C02排放和吸收构成自然界碳循环,可实现C02近零排放。目前,国际上对生物醇类的研究涵盖C1-C8的醇类。其中甲醇是最简单的醇类,作为汽油添加剂,可以有效增加燃料的辛烷值,提高抗爆性,进而改善引擎表现,提高引擎效率。此外,甲醇还是研究其它醇类的模型燃料,因此,对甲醇燃料燃烧反应动力学进行深入研究具有重要意义。作为长链醇类的代表之一,2-甲基-1-丁醇(活性戊醇)是一种含有5个碳原子的醇类,相比分子量较小的甲醇,它表现出诸多明显的优势,比如：能量密度大,具有较低蒸汽压,疏水性强,可与碳氢化合物很好互溶等,因此2-甲基-1-丁醇非常适合作为运输燃料,是不久的将来能作为实际输运燃料中添加剂或替代燃料的热门生物燃料之一。因此,本论文选择短链的甲醇和长链的2-甲基-1-丁醇作为研究对象,深入分析醇类燃料热解和燃烧的基本规律,一方面优化甲醇燃烧模型,使其作为研究醇类燃烧的基本模型；另一方面,以2-甲基-1-丁醇为代表,探索大分子醇类燃料燃烧过程中燃料的分解规律。本文的研究内容主要包括实验和模型研究两大方面,对甲醇开展了火焰传播速度的测量和层流预混火焰的诊断实验,兼顾宏观燃烧参数和微观反应动力学数据的采集。甲醇的层流火焰传播速度测量利用了本组的燃烧弹实验平台,未燃预混燃气温度为423 K,实验测量的燃烧压力条件为1-10 atm。甲醇的层流预混火焰实验借助本组最新研制出的层流预混火焰实验平台,并利用超声分子束取样结合同步辐射真空紫外光电离质谱技术(SVUV-PIMS)展开,测量了甲醇燃烧过程中稳定产物以及活泼中间体的浓度信息,实验压力30Torr,当量1.0。本工作对活性戊醇开展了变压力的流动管热解研究,重点测量其分解过程中初级产物的浓度信息。2-甲基-1-丁醇的变压力流动管热解实验也使用了超声分子束取样结合同步辐射真空紫外光电离质谱技术(SVUV-PIMS),实验压力条件30和760 Torr,温度范围在750-1400 K。此外,基于对前人实验、理论计算和模型研究数据的全面收集,本文构建了甲醇的燃烧反应动力学模型,并利用CHEMKIN-PRO软件对文献和本文实验数据进行了验证,发展并优化了一个能够在宽广实验工况下预测良好的甲醇模型。同时,发展了2-甲基-1-丁醇的热解模型,并与本课题组之前研究的丁醇异构体的热解进行详细对比,探讨了碳链增长和支链结构对醇类燃料热解的影响。具体研究成果如下：首先,通过燃烧弹实验,测量了甲醇1-10 atm下,当量比为0.7-2.1的火焰传播速度。通过分析高压和极富燃条件下的反应机制发现,HO2自由基是高压和富燃条件下火焰传播过程中的主要自由基,与它相关的反应在该条件下对甲醇火焰传播速度的预测非常敏感。本工作更新了氢气机理中涉及H02转化的反应速率常数,以及甲醛和甲醇子机理中H02的生成和消耗反应速率,这些更新会对火焰传播体系自由基池的预测带来较大影响,同时大大改善了前人模型对高压和富燃条件下火焰传播速度的预测。其次,利用SVUV-PIMS方法鉴别了前人无法区分的羟甲基自由基(CH2OH)和甲氧基自由基(CH30),并对羟甲基自由基CH2OH进行定量测量。基于CH2OH的摩尔分数信息,以及实验测得的其它C1产物进行模型研究,发现前人过高估计了由羟甲基自由基生成甲醛的路径,即CH2OH+O2=CH2O+HO2的反应速率在高温下被高估。此外,通过本工作的实验结果验证,发现前人的甲醇模型中C2物种来自甲基复合,效率很低,因此,本工作探讨了羟甲基自由基CH2OH复合生成C2物种的路径,这些反应路径的加入大大改善了模型对C2物种的预测情况。最后,利用SVUV-PIMS方法,对2-甲基-1-丁醇的热解中间体进行全面探测,发展并验证了一个2-甲基-1-丁醇的热解模型。通过对比丁醇异构体热解规律,我们发现2-甲基-1-丁醇的热解机制与异丁醇的热解机制相近,而与正丁醇相差很大。两种支链醇在热解中都表现出单分子解离反应的贡献比H提取反应的贡献要小很多的特点。
[Abstract]:Energy is the driving force and lifeblood of the national economy. The burning of fossil fuels provides 85% of the world and nearly 90% of our country's energy demand. Today, the rapid consumption of fossil fuels has not only brought unprecedented energy crises, but also resulted in environmental pollution, threatening environmental safety and human health. Biological alcohols can be used as a result. Gasoline additives or alternative fuels, on the one hand, can slow down human dependence on fossil fuels. On the other hand, the C02 emission and absorption in the alcohols fuels the natural carbon cycle, which can achieve the near zero emission of C02. At present, the international study of biological alcohols covers the alcohols of C1-C8. Oil additives can effectively increase the octane number of fuel, improve the anti explosion, improve engine performance and improve engine efficiency. In addition, methanol is still a model fuel for other alcohols. Therefore, it is important to study the combustion kinetics of methanol fuel. As one of the representative of long chain alcohols, 2- methyl -1- butanol (Live) Amyl alcohol is a kind of alcohol containing 5 carbon atoms. Compared with methanol with smaller molecular weight, it has many obvious advantages, such as high energy density, low vapor pressure, strong hydrophobicity, and good solubility with hydrocarbons. Therefore, 2- methyl -1- butanol is very suitable as a transport fuel, and it can be used as a practical future in the near future. As one of the hot biofuels of fuel additives or alternative fuels, this paper selects the short chain methanol and the long chain 2- methyl -1- butanol as the research object, and analyzes the basic laws of the pyrolysis and combustion of alcohols. On the one hand, the methanol combustion model is optimized as the basic model for the study of alcohols combustion; the other side is the other side. On the basis of 2- methyl -1- butanol as the representative, the decomposition law of fuel in the combustion process of large molecular alcohol fuel is explored. The main contents of this study include two aspects of experiment and model study. The measurement of flame propagation velocity and the diagnosis of laminar premixed flame are carried out for methanol, and the macro combustion parameters and the number of micro reaction kinetics are taken into consideration. The laminar flame propagation velocity of methanol is measured by the experimental platform of the combustion bomb, the unburned premixed gas temperature is 423 K, the experimental combustion pressure condition is 1-10 atm. methanol in the laminar premixed flame experiment with the latest developed laminar premixed flame experimental platform, and the ultrasonic molecular beam sampling junction is used. The contract step radiation vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was developed to measure the concentration information of the stable products and active intermediates during the process of methanol combustion. The experimental pressure was 30Torr. The active 1.0. was carried out to study the pyrolysis of the active pentyl alcohol, and the concentration information of the primary products during the decomposition process was measured. The 2- methyl -1- butanol variable pressure flow tube pyrolysis experiment also uses ultrasonic molecular beam sampling combined with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), experimental pressure conditions 30 and 760 Torr, and the temperature range is 750-1400 K.. Based on the previous experiments, theoretical calculation and model research data collection, this paper is constructed. The kinetic model of the combustion reaction of methanol was modeled and the CHEMKIN-PRO software was used to verify the literature and the experimental data. A good model of methanol was developed and optimized in a wide range of experimental conditions. At the same time, the pyrolysis model of 2- methyl -1- butanol was developed, and the pyrolysis of butanol isomers before this group was studied. The effects of carbon chain growth and branched chain structure on the pyrolysis of alcohols are discussed in detail. The specific results are as follows: first, the flame propagation velocity of the equivalent ratio of 0.7-2.1 is measured under 1-10 ATM of methanol by the combustion bomb experiment. By analyzing the reaction mechanism under the condition of high pressure and extremely rich combustion, the HO2 radical is high pressure and rich. The main free radicals in the flame propagation process are very sensitive to the prediction of the velocity of the flame propagation of the methanol under this condition. This work updates the reaction rate constant involving the H02 transformation in the hydrogen mechanism, and the formation and consumption of H02 in the mechanism of formaldehyde and methanol. These updates will bring the flame to the flame. The prediction of free radical pool in the propagation system has great influence, and it greatly improves the prediction of flame propagation velocity under high pressure and burning condition. Secondly, the SVUV-PIMS method has been used to identify the hydroxyl radical (CH2OH) and methoxy radical (CH30) which can not be distinguished by predecessors, and the quantitative measurement of hydroxymethyl free radical CH2OH is made. Based on the mole fraction information of CH2OH and the model study of other C1 products measured by the experiment, it is found that the predecessors overestimated the path of the formation of formaldehyde from the hydroxymethyl radical, that is, the reaction rate of CH2OH+O2=CH2O+HO2 was overestimated at high temperature. In addition, the results of this work proved that the former C2 species in the methanol model were found. Self methyl compound has very low efficiency. Therefore, this work explores the path of hydroxyl methyl free radical CH2OH composite generation of C2 species. The addition of these reaction paths greatly improves the prediction of C2 species. Finally, the SVUV-PIMS method is used to fully detect the pyrolysis of 2- methyl -1- butanol, and a 2- A is developed and verified. By comparing the pyrolysis of butanol isomer, we found that the pyrolysis mechanism of 2- methyl -1- butanol is similar to that of isobutanol, but it is very different from that of n-butanol. The contribution of the two kinds of branched alcohols in the pyrolysis of the two kinds of branched chain alcohols is much smaller than that of the H.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK16

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