微通道内单乙醇胺水溶液吸收CO2/N2混合气的传质特性

Mass transfer performance of CO_2/N_2 mixture absorption into monoethanolamine aqueous solution in microchannel

采用高速摄像仪对400μm×400μm T形微通道内单乙醇胺(MEA)水溶液吸收混合气中CO_2过程的气液两相流及传质特性进行了实验研究,微通道内的压力降采用压力传感器进行测量。考察了弹状流型下气液两相流量及MEA浓度对压力降、比表面积和传质性能的影响。结果表明,当MEA浓度不变,气液两相流量增大时,压力降、比表面积、传质系数、体积传质系数和增强因子均增大,并逐渐趋于恒定。当气液流量不变,MEA浓度增大时,压力降、传质系数、体积传质系数和增强因子增大,但比表面积减小。实验条件下,压力降范围为2.00~5.23 kPa,化学吸收过程的传质系数范围为7.74×10^(-4)~2.97×10^(-3) m·s^(-1)。对于伴有快速化学反应的传质过程,以Sherwood数、Reynolds数、Schmidt数及增强因子为变量建立了体积传质系数的预测关联式,平均偏差为5.09%,具有良好的预测性能。

A high speed camera was used to investigate the gas-liquid two-phase flow and mass transfer performance of CO2/N2 gas mixture absorption into monoethanolamine（MEA） aqueous solution in a 400 μm×400 μm T-shape microchannel. The pressure drop along the microchannel was determined by a pressure sensor. The effects of the gas and liquid phase flow rates, MEA concentration on the pressure drop, specific surface area and mass transfer performance were investigated experimentally. The results showed that for a given concentration of MEA aqueous solution, the pressure drop, the mass transfer coefficient, the specific interfacial area, the volumetric mass transfer coefficient and the enhancement factor increased gradually up to a constant value with increasing gas phase or liquid phase flow rates. With increasing MEA concentration or the pressure drop, the mass transfer coefficient, the volumetric mass transfer coefficient and the enhancement factor increased, but the specific interfacial area decreased. Under experimental conditions, the range of pressure drop was 2.00 to 5.23 k Pa and the mass transfer coefficient of gas-liquid two-phase flow accompanied with chemical absorption was ranged from 7.74×10^（-4） to 2.97×10^（-3） m·s^（-1）. A correlation for predicting the volumetric mass transfer coefficient was proposed by taking Sherwood number, Reynolds number, Schmidt number and the enhancement factor into account. The average deviation of the model was 5.09%, indicating a good prediction performance.