蜂窝光纤反应器光催化还原二氧化碳性能分析及结构优化

发布时间：2018-06-17 19:54

本文选题：光催化 + 二氧化碳还原　；参考：《华北电力大学》2015年硕士论文

【摘要】：能源危机和温室效应制约着人类的发展。利用太阳光的光催化还原CO2技术既能控制温室气体排放,又可产生燃料甲醇,富有发展潜力。作为光催化还原CO2反应的载体,蜂窝光纤反应器因其反应速率高、传质能力强备受关注。以蜂窝光纤反应器为对象,以数值模拟为手段,选择合适的反应动力学模型、流动扩散模型等,开展研究。数值模拟结果与已有实验数据吻合,证明数值模拟的可行性。将多根光纤嵌入单个反应通道并改变光源位置,提出多光纤蜂窝反应器。对已有光强分布模型进行分析和推导,得出新的光强分布公式。通过数值实验,得出CH30H浓度与光纤位置和运行参数的变化关系。随着光纤和反应器中心距离、输入光强和水蒸气浓度的增加,CH30H平均浓度增加。但随着入口流速的增加,CH30H平均浓度下降,二者呈反比关系。多光纤蜂窝反应器的CH30H最高出口平均浓度为2.32×10-5 mol·m-3,与蜂窝光纤反应器的结果1.770×10-5mol·m-3相比,提高了31.1%。多光纤蜂窝反应器的最大转化效率和量子效率分别为0.235μmol·g-1·h-1和0.0177%,均高于蜂窝光纤反应器(0.16μmol·g-1·h-1和0.012%)。增加蜂窝光纤反应器的反应层数以扩大反应表面积,得到多反应层蜂窝反应器。结合多光纤模型,继续优化得到多反应层多光纤蜂窝反应器。提出到达反应面的光功率和单位输入功率的产物速率等参数,以更好地对比几种结构的性能。通过光强的积分得到光功率,并发现入口流速和光纤数量一定时,光功率和CH30H浓度呈线性关系。两种优化的结构中,出口CH3OH浓度为3.004×10-5 mol·m-3和3.685×10-5 mol·m-3,分别增加了69.7%和108.2%。光功率的传输效率最大为2.297%,最高的CH30H产率为3.018×10-12mol·s-1.W-1。通过分析不同半径和流速下的浓度场、产物出口浓度和光强,得出多光纤多反应层蜂窝反应器的优化结构为：中层管直径12 mm、长度50 mm。
[Abstract]:The energy crisis and the greenhouse effect restrict the development of human beings. The photocatalytic reduction of CO2 by solar light can not only control the emission of greenhouse gases, but also produce fuel methanol, which has a potential for development. As a carrier for photocatalytic reduction of CO2 reaction, the honeycomb fiber reactor has attracted much attention because of its high reaction rate and high mass transfer capacity. The results of the numerical simulation are consistent with the existing experimental data, which proves the feasibility of the numerical simulation. Multiple optical fibers are embedded in a single reaction channel and the location of the light source is changed, and the existing optical fiber honeycomb reactor is proposed. The distribution model is analyzed and deduced, and a new light intensity distribution formula is obtained. Through numerical experiments, the relationship between CH30H concentration and optical fiber position and operating parameters is obtained. With the center distance of the fiber and reactor, the intensity of input light and the concentration of water vapor increase, and the average concentration of CH30H increases. With the increase of the inlet velocity, the average concentration of CH30H is under the increase of the inlet velocity. The average concentration of the highest CH30H outlet of the multi fiber honeycomb reactor is 2.32 * 10-5 mol. M-3. Compared with the result of the honeycomb fiber reactor 1.770 x 10-5mol. M-3, the maximum conversion efficiency and the quantum efficiency of the 31.1%. multi fiber honeycomb reactor are 0.235 Mu mol, g-1. H-1 and 0.0177% respectively, which are higher than those of the honeycomb light. Fiber reactor (0.16 mol. G-1. H-1 and 0.012%). Increase the number of reaction layers of the honeycomb fiber reactor to enlarge the reaction surface area and obtain the multi reaction layer honeycomb reactor. Combined with multi fiber model, the multi reaction layer multi fiber honeycomb reactor is continuously optimized. The parameters of the light power reaching the reacting surface and the rate of product of the unit input power are proposed. To better compare the performance of several structures. The light power is obtained through the integration of light intensity. The linear relationship between the light power and the CH30H concentration is found when the inlet velocity and the number of fibers are fixed. In the two optimized structures, the export CH3OH concentration is 3.004 * 10-5 mol. M-3 and 3.685 x 10-5 mol. M-3, increasing the transmission of 69.7% and 108.2%. light power respectively. The maximum efficiency of transmission is 2.297%, the highest CH30H yield is 3.018 x 10-12mol. S-1.W-1., through the analysis of the concentration field at different radius and flow rate, the concentration of the product and the light intensity, the optimum structure of the multi fiber multi reaction layer honeycomb reactor is that the diameter of the middle layer is 12 mm, and the length is 50 mm..
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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