【作者】 高小放；

【导师】 辛峰；

【作者基本信息】 天津大学 ， 化学工程， 2007， 硕士

【摘要】 本论文着眼于微通道反应器中的传质过程的研究,分别制作了管径在500μm左右的玻璃毛细管和当量直径为90μm的矩形金属微通道。利用上述设备进行了微通道内水吸收CO2和煤油-水-乙酸的萃取实验。旨在考察特征尺度在微米级的微通道内的气液传质过程和液液传质过程。本文通过实验证明了超快激光刻蚀法在加工微通道反应器中的可行性,并有效利用了常见的玻璃毛细管进行了微通道传质实验。同时,也证明了采用硅橡胶对金属微通道基板并进行机械加固密封的方法是可行的,实验可在一定流速范围内进行传质实验。本文工作通过实践证明,在气体和液体表观流速分别为0.84～7.64m/s和0.08～1.27m/s的范围内,毛细管内的液侧体积传质系数主要受液体表观流速影响,而气体表观流速对传质系数的影响较小。矩形金属微通道内的气液传质实验得到了毛细管内相似的结论,传质系数随液体表观流速的增大而显著增加,气体表观流速随着微通道尺寸的减小而对传质过程的影响愈加微弱。与毛细管微通道相比,由于尺寸的大幅度降低,导致扩散路径的缩短,矩形金属微通道展现了超高的传质性能,有着良好的工业应用前景。微通道内的液液传质实验证明,微通道反应器的优势主要体现在气液相和气液固催化反应中。进一步分析表明,微通道内的不同流体组分通过层流的形式在低流速下依靠分子扩散进行传质,超高的传质效率和缓慢的流体流速是微通道内传质过程的主要特征。同时,由于特征尺度的大幅度减小,也给实验操作的控制和实验结果的分析带来了新的问题,例如特征尺度在400μm以下的设备只能在有限的操作范围内工作。这些都是今后微通道内传质过程的实验研究中所要解决的实际问题。同时也应看到,由于微通道反应器制作成本偏高以及“数增放大”所要面临的许多实际问题,微通道反应器的研究还仅仅处于起步阶段,微通道反应器在化学工业中的大规模实际应用还有很长的一段路要走。更多还原

【Abstract】 This paper focuses on the researches of the mass transfer in a microchannel reactor. Experiments on absorption of carbon dioxide in water and the extraction between kerosene, water and acetic acid have been carried out in a rectangular metal microchannel etched by ultra-fast laser and 3 groups of glass capillaries. The rectangular metal microchannel and the glass capillaries have a hydrodynamic diameter of 90μm and capillary diameters around 500μm respectively. The aim of this work is to investigate the behaviors of the gas-liquid and liquid-liquid mass transfer in a microchannel.It has been proved to be feasible to make a microchannel by ultra-fast laser and also it is proper to seal the metal microchannel by mechanic method in favor of silicone rubber. The experiments can be operated in range of some liquid velocities and the normal glass capillaries have been utilized as well. Our work has shown that in glass capillaries the liquid side volumetric mass transfer coefficient has more influence by the superficial liquid velocity of 0.08～1.27m/s rather than the superficial gas velocity of 0.84～7.64m/s. Similar conclusions can be attained in the rectangular metal microchannel that the superficial liquid velocity is the dominated factor in mass transfer rather than the superficial gas velocity, but compared to the glass capillaries, the mass transfer coefficient is extraordinarily high due to the notable reduction of the hydrodynamic diameter and the length of diffusion distance and it has a good foreground in industry. Liquid-liquid mass transfer experiment showed that the microchannel has a predominance especially in gas-liquid and gas-liquid-solid catalytical reactions. Further analysis suggest that in a microchannel the mass transfer of different phases relies on the molecular diffusion under laminar flow and in low liquid velocity thus extraordinarily high efficiency and low liquid velocity are the main characteristics of mass transfer in a microchannel. Due to the notable reduction of the characterizing size new problems such as the control of experimental operation and the analysis of the results have been presented. For instance, apparutus which has a characterizing size under 400μm can only work in a limited range. These practical problems need to be worked out in the future experimental research on mass transfer in a microchannel. Microchannel reactors still have a lot of problems suspended such as a high cost in fabrication and the“numbering up”. The mass production of microreators in chemical industry still has a long way to go.更多还原