基于压电驱动的高频振动自循环式微流体反应器设计与实验研究

发布时间：2018-02-02 04:51

本文关键词： 微流体反应器压电微泵高频振动自循环银纳米粒子可控合成　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：微流体反应器因具试剂消耗少、反应效率高、安全可控等优点,在化工领域内有着巨大优势。目前,对微流体反应器的研究多数以溶液间的快速混合以及精确配比为主,而对需要一定空间及时间的溶液反应研究较少。本文以压电驱动技术为基础、以压电微泵制作工艺为依托,提出了一种高频振动自循环式微流体反应器,它一方面通过压电微泵的主动自循环回流,促使溶液均匀混合反应,另一方面,利用振动基底的高频振动均衡反应条件,抑制微粒间的团聚。它是一种主动性更强、过程可控的新型微流体反应器,适用于反应过程复杂、反应时间长、需要主动搅拌的化学反应,尤其适用于贵金属纳米粒子的液相合成反应。具体研究内容如下:通过建立压电振子的理论弯曲模型,得出影响压电振子最大挠度的参数;利用ANSYS软件建立压电振子的分析模型,对其进行模态分析及谐响应分析,确定一阶振型为纯弯曲振型,并且当激励频率为压电振子的谐振频率时,压电振子响应位移最大,最具驱动能力。利用COMSOL软件对混合池结构进行流体仿真分析,流动特性表明在入口雷诺数较高时,混合池中形成涡旋流动,混合以对流为主,涡旋越明显,混合效果越好。通过仿真确定U形结构为单出入分布的最佳结构以及W/D=1/12为最佳结构参数,并基于U形结构特点提出的多出入口分布的混合池结构,其性能要优于单出入口分布的混合池结构;在混合池中间增加圆形或叶片形障碍物,并没有起到加强混合的效果的作用。设计制作基于压电驱动的高频振动自循环式微流体反应器,并进行了关于压电微泵、自循环回流、振动基底等性能测试。测试结果表明:压电微泵的输出流量和输出压力,均随着驱动电压的增大而近似线性增大。当驱动频率在80~120Hz时,压电微泵的输出流量和输出压力均处于较高水平;当驱动频率在160~200Hz时,压电微泵输出流量小,但频率的波动对流量的影响甚微。在自循环回流微泵频率为100Hz条件下,随着驱动电压增大,涡旋转速越快,当驱动电压为80V时,涡旋转速高达263r/min。在混合池注满0.4ml水的情况下,振动基底的谐振频率为3.85kHz,并在此频率下,振子的最大振幅随着电压增大而增大。当驱动电压为100V时,高频振动能够振散开磁性陶瓷颗粒,当驱动电压大于120V时,高频振动会产生雾化现象。利用自制的微流体反应器进行硼氢化钠还原硝酸银合成银纳米粒子的实验,验证其在贵金属纳米粒子合成等复杂化学反应中的应用优势。实验结果表明PVP作为一种保护分散剂,能够有效地抑制银纳米粒子的团聚。自循环回流对粒子的合成产生影响,随着驱动电压的增大,涡旋转速越快,反应试剂混合越均匀,合成的纳米粒子球形度越高、单分散性越好;高频振动对粒子的合成也产生影响,只有当驱动频率为谐振频率时,振动基底才能发挥高频振动的最佳效果,不仅能够均衡粒子成长环境,还能够抑制纳米粒子的团聚,有利于合成球形度高、单分散性好、粒径分布均匀的纳米粒子。另外实验还分析硝酸银与硼氢化钠的浓度比对银纳米粒子的影响,当两者浓度比为1:4时,合成的银纳米粒子浓度最高,平均粒径大小为9.86nm,且尺寸分布范围小、球形度高、单分散性好。
[Abstract]:A microfluidic reactor with less reagent consumption, high reaction efficiency, safe and controllable, has tremendous advantages in the field of chemical industry. At present, most studies on microfluidic reactor with fast mixed solution and accurate proportion, less on the solution reaction research requires a certain time and space. This is based on the piezoelectric driving technology, the piezoelectric micro pump manufacturing technology as the basis, put forward a kind of high frequency vibration self circulating micro fluid reactor, it through a piezoelectric micro pump automatic circulation enables the solution mixing reaction, on the other hand, the use of high frequency vibration vibration equilibrium reaction conditions of substrate. Inhibition of particles reunion. It is a more active, controllable new microfluidic reactor suitable for complex reaction process, reaction time, reaction to active mixing, especially suitable for precious metals Nanoparticles by liquid phase synthesis. The specific contents are as follows: the theory of bending model of the piezoelectric vibrator, the parameters affecting the maximum deflection of the piezoelectric vibrator; establish the analysis model of piezoelectric vibrator by using ANSYS software, modal analysis and harmonic response analysis on the determination of the first-order mode for pure bending mode, and when the excitation frequency is the resonance frequency of the piezoelectric vibrator, piezoelectric vibrator response displacement is the biggest, the most driving capability. The fluid simulation analysis of mixed pool structure by using COMSOL software, the flow characteristics show at the entrance Reynolds number is high, the formation of vortex flow mixing tank, mixing by convection, the vortex is more obvious, the mixing effect is better. Through simulation to determine the U structure for single entry structure and the distribution of the best W/D=1/12 for the best structural parameters, and based on the U structure characteristics of entrance distribution of mixed pool structure And its performance is superior to the single mixed pool entrance distribution structure; increase the circular or blade shape obstacles in the mixed pool middle, did little to enhance mixing effect. The high frequency vibration of the piezoelectric drive design based on self circulation microfluidic reactor, and carried on the piezoelectric micro pump, self circulation, vibration substrate performance test. The test results show that the piezoelectric micro pump output flow rate and pressure are increased with the increase of drive voltage linearly increases. When the driving frequency at 80~120Hz, piezoelectric micro pump output flow rate and pressure are at a high level; when the driving frequency in 160~200Hz piezoelectric micro pump, the output flow is small, but the frequency fluctuations have little effect on the flow. The self circulation micro pump frequency of 100Hz conditions, with the driving voltage increases, the vortex speed more quickly, when the driving voltage of 80V, high speed vortex 263r/min. 0.4ml was filled with water in the mixing tank under the condition that the resonance frequency of the vibrating substrate is 3.85kHz, and the frequency, the maximum amplitude of the oscillator increases as the voltage increases. When the driving voltage of 100V, high frequency vibration isolation can disperse magnetic ceramic particles, when the driving voltage is greater than 120V, high frequency vibration will produce atomization the phenomenon. The sodium borohydride reduction of silver nitrate synthesis of silver nanoparticles using self-made microfluidic reactor experiments to verify its application advantages in synthesis of noble metal nanoparticles and other complex chemical reaction. The experimental results show that PVP as a protective dispersing agent, can effectively inhibit the aggregation of silver nanoparticles. The self circulation reflux synthesis influence the particles, with the increase of drive voltage, scroll faster the speed, the reagent mixture is more uniform, the synthesis of spherical nanoparticles is higher, more good monodispersity; high frequency vibration The synthesis of particles was also affected, only when the driving frequency of the resonant frequency, vibration base to achieve the best results of the high frequency vibration, can not only balance the particle growth environment, but also can inhibit the agglomeration of nanoparticles, is conducive to the synthesis of high sphericity, monodisperse nanoparticles, uniform particle size distribution. Additionally analysis of the effect of silver nitrate and sodium borohydride concentration ratio of silver nanoparticles, when the concentration is 1:4, the synthesis of silver nanoparticles was the highest, the average particle size is 9.86nm, and the size distribution range of small, high sphericity, good monodispersity.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ052

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