Hayato Masuda

Prediction of onset of Taylor-Couette instability for shear-thinning fluids

AbstractThe definition of Reynolds number (Re) in a Taylor-Couette flow for a shear-thinning fluid is discussed in this paper. Since the shear-thinning property causes spatial distribution of fluid viscosity in a Taylor-Couette flow reactor (TCFR), a method to determine Re by using a numerical simulation is suggested. The effective viscosity (ηeff) in Re was the average viscosity using a weight of dissipation functionηeff=∑i=1Nγ⋅i2ηiΔVi/∑i=1Nγ⋅i2ΔVi,

Process intensification of continuous starch hydrolysis with a Couette–Taylor flow reactor

{\eta}_{\mathrm{eff}}={\displaystyle \sum_{i=1}^N{\overset{\cdot }{\gamma}}_i^2{\eta}_i\Delta {V}_i}/{\displaystyle \sum_{i=1}^N{\overset{\cdot }{\gamma}}_i^2\Delta {V}_i},

Numerical Analysis of the Flow of Fluids with Complex Rheological Properties in a Couette-Taylor Flow Reactor

where N is the total mesh number, ηi (Pa·s) is the local viscosity, γ⋅i

Flow Dynamics in Taylor–Couette Flow Reactor with Axial Distribution of Temperature

{\overset{\cdot }{\gamma}}_i

Intensification of Heat Sterilization Process for Liquid Foods Using Taylor-couette Flow System

(1/s) is the local shear-rate, and ΔVi (m3) is the local volume for each cell. The critical Reynolds number, Recr, at which Taylor vortices start to appear, was almost the same value with the Recr obtained by a linear stability analysis for Newtonian fluids. Consequently, Re based on ηeff could be applicable to predict the occurrence of Taylor vortices for a shear-thinning fluid. In order to understand the relation between the rotational speed of the inner cylinder and the effective shear rate that resulted in ηeff, a correlation equation was constructed. Furthermore, the critical condition at which Taylor vortices appear was successfully predicted without further numerical simulation.

Thermal treatment of starch slurry in Couette-Taylor flow apparatus

In food industries, enzymatic starch hydrolysis is an important process that consists of two steps: gelatinization and saccharification. One of the major difficulties in designing the starch hydrolysis process is the sharp change in its rheological properties. In this study, Taylor–Couette flow reactor was applied to continuous starch hydrolysis process. The concentration of reducing sugar produced via enzymatic hydrolysis was evaluated by varying operational variables: rotational speed of the inner cylinder, axial velocity (reaction time), amount of enzyme, and initial starch content in the slurry. When Taylor vortices were formed in the annular space, efficient hydrolysis occurred because Taylor vortices improved the mixing of gelatinized starch with enzyme. Furthermore, a modified inner cylinder was proposed, and its mixing performance was numerically investigated. The modified inner cylinder showed higher potential for enhanced mixing of gelatinized starch and the enzyme than the conventional cylinder. Graphical abstract Even the high starch content of the slurry was effectively and continuously hydrolyzed in Taylor vortex flow region (high effective Reynolds number region).