Abstract:

A high speed camera was used to investigate the mass transfer performance of CO₂ absorption into aqueous mixture of monoethanolamine with N-methyldiethanolamine in T-shaped microchannel. Effects of two-phase flow rates, MEA and MDEA concentrations on liquid mass transfer coefficient k_Land volumetric mass transfer coefficient k_La were investigated under slug flow. The mass transfer coefficient and volumetric mass transfer coefficient increased with the increase of MEA concentration, however, the MDEA concentration had an relatively small effect on mass transfer. The mass transfer coefficient and volumetric mass transfer coefficient increased with the increase of the liquid flow rate. The volumetric mass transfer coefficient increased rapidly, and then tended to a constant with gas flow rate, but the mass transfer coefficient was insensitive to gas flow rate. Considering the strengthening effect of chemical reaction on mass transfer, the Hatta number Ha is introduced, and a new volumetric mass transfer coefficient prediction formula is proposed. The predicted values agreed well with the experimental data.

Key words: microchannels, carbon dioxide, two-phase flow, mass transfer, chemical absorption

摘要：

研究了T形微通道内N-甲基二乙醇胺（MDEA）和单乙醇胺（MEA）混合水溶液吸收CO₂的传质过程。考察了弹状流型下气液两相流量、MEA和MDEA浓度对液侧传质系数k_L和体积传质系数k_La的影响。液侧传质系数和体积传质系数均会随着MEA浓度的升高而升高。与MEA相比，MDEA浓度的提高对传质影响较小。传质系数会随着液体流量的增大而增大，但气体流量的变化对其影响较小。体积传质系数随液体流量的增大而增大，但随气体流量的增大先增大，之后趋于稳定。考虑到化学反应对传质的强化作用，引入了Hatta数，提出了一个新的体积传质系数预测式，预测效果良好。

关键词: 微通道, 二氧化碳, 两相流, 传质, 化学吸收