(600cq) The Intensification of Mass Transfer of CO2 Bubble Absorption Into Monoethanol Amine (MEA) Aqueous Solution in a Rectangular Microchannel

The
intensification of mass transfer of CO₂ bubble absorption into monoethanol amine (MEA) aqueous solution in a rectangular microchannel

Xiqun
Gao^a, Chunfang Li^b,
Taotao Fu^b, Youguang
Ma^b*

^a
Yifang
Industry Corporation, Liaohua Petrochemical Fiber
Company, Liaoyang
111003, P. R. China

^bState Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China

* Corresponding
author: ygma@tju.edu.cn

Abstract: This
article aims at studying the absorption process of CO₂ bubbles in monoethanol amine (MEA) aqueous solutions in microchannels by using a high-speed digital camera. Experiments
were conducted in a polymethyl methacrylate (PMMA) rectangular
microchannel with 600 µm wide and 400 µm deep. The
parameters affecting the bubble length such as
the concentration of monoethanol amine (MEA) aqueous
solutions, gas and liquid flow rates were
studied. The dissolution process of CO₂ bubbles in monoethanol amine (MEA) aqueous solutions in microchannels was characterized by
the diminishing of the bubble length with time
. The results showed that the slug bubble flow was
transformed into the bubbly flow with the movement of bubbles in microchannels. The length of the slug bubble reduced
exponentially with time to a relative stable length, and then the small bubble dissolved
at a quite slow speed. The dissolution speed for the slug bubble decreased with
the decrease of the concentration of monoethanol amine
(MEA) aqueous solutions and the liquid flow rates, and with the increase of the
gas flow rates. The instantaneous mass transfer coefficient on the liquid side
was correlated by means of the diminishing speed of the
bubble length
, based on the mass conservation law for a single bubble. The
ratio of interfacial area to volume a
was calculated directly from the images for the absorption process of CO₂
bubbles in monoethanol amine (MEA) aqueous solutions
in microchannels. And a new correlation of volumetric
mass transfer coefficient on the liquid side
 was proposed by
taking into account the influences of the concentration of monoethanol
amine (MEA) aqueous solutions, and the gas and liquid flow rates. The results showed
that the absorption of CO₂ bubbles in monoethanol
amine (MEA) aqueous solutions was intensified significantly by the
miniaturization of the device.

Keywords: CO₂
bubble; dissolution; microchannel; miniaturization;
process intensification