Abstract:

A gas-phase necked T-shaped microchannel was constructed, and the gas-liquid two-phase flow and mass transfer performance of silicon dioxide (SiO₂) nanofluids in the process of CO₂ absorption were studied. In the experimental range, the bubbly flow, beaded bubble flow, compact slug flow, and slug-annular flow were observed. With the increase of gas phase flow rate, the bubble formation frequency f and the specific surface area a of bubbly flow increase rapidly, f and a of beaded bubble flow change little, and f and a of compact slug flow gradually decrease. Moreover, the liquid-phase volumetric mass transfer coefficient showed an increasing trend with the rise of the flow rate of both continuous and dispersed phases and the nanoparticle concentration in the liquid. Compared to the equal width T-channel, the maximal specific surface area of the microchannel with the narrow gas-phase inlet increased by 29.6%. It is shown that the reduction effect of gas phase inlet can effectively increase the mass transfer area of gas-liquid two-phase flow, which is conducive to the improvement of gas-liquid mass transfer performance.

Key words: CO₂ capture, nanofluids, microchannel, mass transfer, process enhancement

摘要：

构建了一种气相缩口的T型微通道，研究了二氧化硅(SiO₂)纳米流体吸收CO₂过程的气液两相流动与传质性能。在实验范围内，观察到了泡状流、串珠流、紧密弹状流和弹状-环状流。随着气相流速的增加，泡状流的气泡生成频率f和比表面积a快速增大，串珠流的f和a变化很小，紧密弹状流的f和a逐渐减小。随着连续相和分散相流速的增大以及纳米颗粒浓度的升高，液侧体积传质系数均表现出增大的趋势。与等宽T型通道相比，缩口T型微通道的最大比表面积增幅达29.6%。结果表明气相入口的缩径效应可有效提高气液两相流的传质面积，有利于气液传质性能的改善和提高。

关键词: 二氧化碳捕集, 纳米流体, 微通道, 传质, 过程强化