Takafumi Horie

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 development of starch hydrolysis using mixing characteristics of Taylor vortices

{\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},

Cutting-Edge Research at the Membrane Center in Kobe University in Japan

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

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

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

Application of picene thin-film semiconductor as a photocatalyst for photocatalytic hydrogen formation from water

(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.

Process Development for Ultrasonic Fracturing of Zirconium Phosphate Particles

This study investigated the effect of pretreatment of ultrasonic irradiation on emulsion polymerization of styrene to propose a process intensification method which gives high conversion, high reaction rate, and high energy efficiency. The solution containing styrene monomer was irradiated by a horn mounted on the ultrasonic transducer with the diameter of 5mm diameter and the frequency of 28 kHz before starting polymerization. The pretreatment of ultrasound irradiation as short as 1 min drastically improved monomer dispersion and increased reaction rate even under the agitation condition with low rotational speed of impeller. Furthermore, the ultrasonic pretreatment resulted in higher monomer concentration in polymer particles and produced larger polymer particles than conventional polymerization without ultrasonic pretreatment.