Experimental measurement of oxygen mass transfer and bubble size distribution in an air–water multiphase Taylor–Couette vortex bioreactor

Abstract

h i g h l i g h t sMean bubble size, and size distribution in vertical gas-liquid Taylor vortex flow. Mass transfer coefficients for vertical gas-liquid Taylor vortex flow. Wall-driven shear produces prolate rather than oblate bubble shapes. Bubble size and spatial distribution explains low mass transfer coefficients. High wall area in annular geometry has significant impact on mass transfer. a b s t r a c tExperimental measurements of the volumetric liquid mass transfer and bubble size distribution in a vertically oriented semi-batch gas-liquid Taylor-Couette vortex reactor with radius ratio g = r i /r o = 0.75 and aspect ratio C = h/(r o À r i ) = 40 were performed, and the results are presented for axial and azimuthal Reynolds number ranges of Re a = 11.9-143 and Re H = 0-3.5 Â 10 4 , respectively. Based on these data, power-law correlations are presented for the dimensionless Sauter mean diameter, bubble size distribution, bubble ellipticity, and volumetric mass transfer coefficient in terms of relevant parameters including the axial and azimuthal Reynolds numbers. The interaction between wall-driven Taylor vortices and the axial passage of buoyancy-driven gas bubbles leads to significantly different dependencies of the mass transfer coefficient on important operating parameters such as inner cylinder angular velocity and axial superficial gas velocity than has been observed in horizontally oriented gas-liquid Taylor vortex reactors. In general, the volumetric mass transfer coefficients in vertical Taylor vortex reactors have a weaker dependence upon both the axial and azimuthal Reynolds numbers and are smaller in magnitude than those observed in horizontal Taylor vortex reactors or in stirred tank reactors. These findings can be explained by differences in the size and spatial distribution of gas bubbles in the vertically oriented reactor in comparison with the other systems.

Characteristic time scales of mixing, mass transfer and biomass growth in a Taylor vortex algal photobioreactor

“…(5)-(8)) for the oxygen volumetric mass transfer coefficient k L a (O 2 ) in a vertical Taylor vortex reactor identical to the reactor used here was recently developed by Ramezani et al (2015). By making use of this correlation and Eq.…”

“…Experimental details concerning the development of the correlations given by Eqs. (5) and (6) can be found in Ramezani et al (2015), who used a minimally invasive oxygen sensing system (PreSens Fibox 4 transmitter and Pst3 sensor spots) to measure time-dependent dissolved oxygen concentrations in response to step input changes. From Eqs.…”

“…For an air-water system, the volumetric mass transfer coefficient for oxygen, k L a (O 2 ), in a vertically-oriented Taylor vortex PBR at room temperature can be computed from correlations recently developed by Ramezani et al (2015), given by: …”

“…an annular bubble column with no cylinder rotation). However, it should be noted that gas-liquid mass transport is also significantly enhanced by the presence of Taylor vortices (Ramezani et al, 2015), and as a result the question arises as to whether algal growth rate enhancements in these devices is attributable primarily to the creation of L/D cycles, to improved interphase mass transport of carbon dioxide and oxygen, or to a combination of both effects. Hence, the purpose of this report is to describe the findings of a series of batch culture experiments designed to determine characteristic times for liquid mixing, gas-liquid mass transfer, and algal biomass growth in a Taylor-Couette PBR for a range of reactor inner cylinder rotation speeds, feed gas flow rates, and feed gas compositions.…”

Thermal treatment of starch slurry in Couette-Taylor flow apparatus

“…Moreover, in the case of some non-Newtonian (shear-tinning) fluids the reduction in their apparent viscosity can be expected when rotor rotation increases. Additionally, it is worth pointing out that a CTF apparatus provides good environment for the cpe.czasopisma.pan.pl; degruyter.com/view/j/cpe intensification of various processes, e.g., multiple emulsion preparation (Dłuska and MarkowskaRadomska, 2010), processes involving gas-liquid flows (Dłuska and Hubacz, 2000), mass transfer in bioreactors (Ramezani et al, 2015), crystallization (Mayra and Kim, 2015).…”