Publication Date:
2017-09-16
Description:
The efficient control of microbubbles is achieved by using the alcohol shear flows in ceramic membrane channels. The dependence of hydrodynamic and mass transfer properties of microbubbles on liquid viscosity is investigated in a bubble column with 32 mm i.d. and 800 mm height. The multi-channel ceramic membrane with an average pore size of 200 nm works as the gas sparger, and the shear flow on the membrane surface controls the microbubble generation. Oxygen gas and glycerin solutions with different viscosities (μ l = 1 - 42 mPa·s) are used as gas phase and liquid phase, respectively. The microbubbles are massively generated at different liquid viscosities. With increasing viscosity, the bubble size first decreases (μ l 〈 2.0 mPa·s) and then increases. The dual effect of viscosity on bubble size is related to bubble coalescence. In low viscosity range, increasing viscosity hinders liquid film drainage and thus inhibits coalescence. At high viscosity, liquid turbulence intensity is weakened and bubble coalescence is enhanced. However, the dual effect of viscosity on gas holdup is not observed for microbubble. Increasing viscosity makes the monotonic increase in Sauter diameter and specific interfacial area, while the mass transfer coefficient decreases as viscosity increases at small cross flow velocities.
Print ISSN:
0930-7516
Electronic ISSN:
1521-4125
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
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