Papers - Terasaka, Koichi

Experimental study and prediction by computational fluid dynamics on self-induced sloshing due to bubble flow in a rectangular vessel

Aoki R., Fujioka S., Terasaka K.

Journal of Chemical Engineering of Japan (Journal of Chemical Engineering of Japan)  54 ( 2 ) 51 - 57 2021

ISSN  00219592

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Self-induced sloshing is an oscillatory phenomenon of a free liquid surface due to the flow of a fluid. This phenomenon has been reported in some gas–liquid reactors, and it is important to predict and prevent its occurrence for the safe operation of the reactors. However, the fundamental knowledge on the self-induced sloshing by bubble flow, such as the frequency and amplitude, is insufficient, and the occurrence condition has not been clarified. The purpose of this study is to investigate the characteristics of self-induced sloshing by bubble flow experimentally. We attempt to reproduce self-induced sloshing by using computational fluid dynamics (CFD) and establish a CFD model for the prediction of the occurrence of self-induced sloshing. In the experiments, air bubbles were dispersed into a liquid from the bottom of a rectangular vessel. The effects of the air flow rate and static liquid height on the characteristics of self-induced sloshing were investigated experimentally by image analysis. The occurrence of self-induced sloshing was confirmed by increasing the airflow rate at a specific static liquid height. The amplitude reached a maximum at the static liquid height, where self-induced sloshing was most likely to occur, and the frequency decreased with increasing static liquid height. Next, in order to reproduce the self-induced sloshing through CFD, an appropriate drag model of the bubbles was selected. Although the amplitude was overestimated due to the absence of the foam layer, the predicted frequency agreed well with the experimental value. Finally, the movement of the circulation flow was analyzed, and its correlation with the self-induced sloshing was clarified.

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Characterization of water/organic biphasic system in liquid-liquid slug flow under hydrothermal conditions: Solvation, vorticity, and hydrophobicity

Shimanouchi T., Fujioka S., Tanifuji T., Yamamoto K., Terasaka K., Kimura Y.

Solvent Extraction Research and Development (Solvent Extraction Research and Development)  28 ( 1 ) 21 - 35 2021

ISSN  13417215

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The microcapillary was combined with the liquid-liquid slug flow to build the separation field. The partition behavior of seventeen kinds of substrates was investigated by using six kinds of water/organic biphasic systems under hydrothermal conditions (25 - 190° C at 10 MPa). The scale of hydrophobicity (HF) of water/organic biphasic system was estimated. The HF value for the biphasic system used here was comparable to the conventional aqueous two-phase systems and depended on the (de)solvation of substrates by water and organic solvent. Besides, the vortex field in the slug contributed to the enhanced mass transfer of substrates. Those results are available for the selection of water/organic biphasic system as the reactive separation of target materials.

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加減圧の繰り返し操作による水中からのウルトラファインバブル生成

山崎京香,　寺坂宏一,　藤岡沙都子

混相流 (日本混相流学会)  34 ( 4 ) 532 - 540 2020.12

Research paper (scientific journal), Joint Work

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Hydrodynamic and Mass Transfer Correlation in a Microbubble Aerated Stirred Tank Reactor

Simon Matthes, Benjamin Thomas, Daniel Ohde, Marko Hoffmann, Paul Bubenheim, Andreas Liese, Shunya Tanaka, Koichi Terasaka, Michael Schlueter

the Journal of Chemical Engineering of Japan (JOURNAL OF CHEMICAL ENGINEERING OF JAPAN )  53 ( 10 ) 577 - 584 2020.10

ISSN  Print ISSN : 0021-9592

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© 2020 The Society of Chemical Engineers, Japan Many chemical and biocatalytic reactions are consuming gaseous species like oxygen, provided by the mass transfer across interfaces of multiphase contact apparatuses. For biocatalytic reactions a macroscopic aeration can lead to reduced enzyme activity by foaming and shear forces and for fast chemical reactions in multiphase flows, the mass transfer limitation is often the bottleneck for a process optimization. The present study investigates the use of bubbles with diameters less than 100 µm for aeration of a 3 L lab scale stirred tank reactor. For demineralized water and a solution of glucose and bovine serum albumin (BSA) as biocatalytic model protein solution, two different membrane spargers with a mean pore size of 1 µm and 2 µm are investigated. Determining the influence of the energy input on the hydrodynamics of the system, endoscopic measurements of bubble size distributions are carried out. The mass transfer performance of the two spargers is analyzed by measurements of the oxygen kla value for varying gas flow rates. As a result microbubble aeration shows a significant higher mass transfer performance compared to an open tube aeration saving 60% of the gaseous phase by reaching the same kla values. Besides high specific interfacial areas and long residance times, the Laplace pressure inside the bubble is identified as an enhancing force for mass transfer at microscale.

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Production of Oxygen Ultrafine Bubble Water with Spray Injection from a Pressurized Container

山崎京香,　寺坂宏一,　藤岡沙都子

混相流 (日本混相流学会)  34 ( 3 ) 436 - 443 2020.09

Research paper (scientific journal), Joint Work

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Generation and Long-Term Stability of Ultrafine Bubbles in Water

Tanaka S., Terasaka K., Fujioka S.

Chemie-Ingenieur-Technik (Chemie-Ingenieur-Technik)  93 ( 1-2 ) 168 - 179 2020

ISSN  0009286X

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© 2020 Wiley-VCH GmbH This study investigated submicron-sized bubbles, more precisely ultrafine bubbles (UFBs). The number concentration, size, and scattered light intensity of UFBs were measured by particle tracking analysis (PTA). The results showed that storage temperature had a significant effect, whereas the storage containers had little effect on the long-term stability of UFBs. It was found that the second-order aggregation rate equation could predict the stability of UFBs; however, there were some differences from the theory at high storage temperatures. The features of the PTA were also discussed in detail.

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Dissolution and Shrinking of a Single Microbubble in Stationary Liquid with Surfactants

Fujioka S., Mizuno K., Terasaka K.

Chemie-Ingenieur-Technik (Chemie-Ingenieur-Technik)  93 ( 1-2 ) 216 - 222 2020

ISSN  0009286X

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© 2020 Wiley-VCH GmbH For a variety of applications of microbubbles, it is necessary to clarify the dissolution dynamics and the lifetime of a microbubble. Although various models have been proposed, predicting the dissolution rate of a microbubble in a static fluid with a surfactant is still difficult. In this study, dissolution behavior was predicted with taking into account the mass transfer inhibition effect due to a surfactant at the bubble surface. The shrinking behavior of an oxygen microbubble was observed with several surfactants and the experimental results were in good agreement with model predictions.

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Concentration and dilution of ultrafine bubbles in water

Tanaka S., Naruse Y., Terasaka K., Fujioka S.

Colloids and Interfaces (Colloids and Interfaces)  4 ( 4 )  2020

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Submicron-sized bubbles are now officially called ultrafine bubbles (UFBs) by the international standard. The concentration of UFBs is generally low (<109 particles/mL; <0.001 vol%) compared to other colloidal dispersions. To overcome this practical problem, we concentrated UFBs in ultrapure water prepared by a commercial UFB generator and quantified the effect of rotary evaporation of the dispersion media on the stability of UFBs. The UFB dispersions were characterized by a particle tracking analysis (PTA) instrument. The experimental results showed that the UFBs can be diluted and concentrated without changing the size distribution and there was little or no loss of UFBs. By using a rotary evaporator, UFB dispersions were about 30-fold concentrated and the resultant number concentration reached over 3 × 1010 particles/mL. Increasing the concentration of UFBs allowed for satisfactory dynamic light scattering (DLS) measurements. The differences among the three algorithms for analyzing the raw data, i.e., autocorrelation function, obtained by DLS are discussed, along with the characteristics of the particle size distribution derived from each algorithm.

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Fine Bubble-based CO<inf>2</inf> Capture Mediated by Triethanolamine Coupled to Whole Cell Biotransformation

Ohde D., Thomas B., Matthes S., Percin Z., Engelmann C., Bubenheim P., Terasaka K., Schlüter M., Liese A.

Chemie-Ingenieur-Technik (Chemie-Ingenieur-Technik)  91 ( 12 ) 1822 - 1826 2019.12

ISSN  0009286X

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© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Carbon capture technology can be set up in combination with biocatalysis to utilize the bound CO2 as substrate in the Kolbe-Schmitt like enzymatic reaction. The exemplary whole cell biotransformation of catechol to 2,3-dihydroxybenzoic acid in a triethanolamine-mediated multiphase system shows increased equilibrium conversion. Apart from the beneficial thermodynamics, the inherent fluid properties of triethanolamine is enabling easy application of CO2 fine bubbles as highly efficient gassing method to minimize the CO2 demand and CO2 emissions.

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Absorption of Carbon Dioxide at High Temperature with Molten Alkali Carbonate Using Bubble Column Reactor

Yugo Kanai, Koichi Terasaka, Satoko Fujioka, Kenichirou Fukunaga

Journal of Chemical Engineering of Japan (The Society of Chemical Engineers, Japan)  52 ( 1 ) 31 - 40 2019

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00219592

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© 2019 The Society of Chemical Engineers, Japan The purpose of this study is to examine the possibility of establishing a novel CO 2 absorption process with molten alkali carbonate using a bubble column reactor. In our previous study, a hot CO 2 recovery process using Li 4 SiO 4 suspended in molten Li 2 CO 3 -K 2 CO 3 was developed. In the process, molten alkali carbonate itself showed great potential for CO 2 absorption at high temperature. If a hot CO 2 absorption process were established using only molten alkali carbonate, it could make the system simpler and the operating temperature range could be extended without the limitation of reaction temperature of solid absorbent. In the study, molten Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 and its eutectic mixture were selected as CO 2 absorbent. A bubble column was chosen as the device for gas absorption at high temperature. First, the CO 2 absorption performance of each single molten alkali carbonate was investigated. The result showed that the molten Li 2 CO 3 had a great ability to absorb CO 2 at high temperature. Li 2 O was thought to be produced by decomposition of Li 2 CO 3 during the melting and purging process and a reaction of CO 2 with Li 2 O occurred during the absorption process. Further, the CO 2 absorption performance of eutectic mixture increased exponentially with increasing the ratio of Li 2 CO 3 in composition. Second, the possibility of establishing a CO 2 absorption process using molten Li 2 CO 3 was examined. The overall CO 2 absorption process in the bubble column was investigated and the experimental results showed that the mass transfer of CO 2 into molten Li 2 CO 3 was the rate-controlling step. The operational conditions of the bubble column were optimized. The superficial gas velocity was an important operational parameter that affected both the CO 2 absorption rate and total amount of CO 2 finally absorbed in the bubble column. The operating temperature also greatly affected the amount of absorbed CO 2 .

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Mass transfer from freely rising microbubbles in aqueous solutions of surfactant or salt

Tanaka S., Kastens S., Fujioka S., Schlüter M., Terasaka K.

Chemical Engineering Journal (Chemical Engineering Journal)  387 2019

ISSN  13858947

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© 2019 Elsevier B.V. Microbubbles are used in many applications. One of the major advantages of using microbubbles is to improve the mass transfer of gases to the bulk phase. In this study, mass transfer from single microbubbles that rise in ultrapure water and aqueous solutions of surfactants (SDS, Pluronic F68) or salt (NaCl) was investigated. The rising and dissolution behaviors of single air microbubbles were observed using a high-speed imaging technique by which the rising velocity, U B , and the mass transfer coefficient, k L , were optically evaluated. We found that the rising velocity of microbubbles obeys Stokes’ law, indicating that the surface of the microbubbles used in this study is immobile, despite their rising in ultrapure water. The obtained mass transfer coefficients were in good agreement with those predicted by Ranz and Marshall's correlation for the Sherwood number, Sh. Using the two correlations for U B and Sh, a theoretical model that describes the mass transfer from a microbubble was constructed. The proposed model can predict the dissolution of single microbubbles rising in ultrapure water and aqueous solutions with an accuracy of ±10% in terms of dissolution time.

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Fine bubble based CO2 capture mediated by triethanolamine coupled to whole cell biotransformation

Andreas Liese, Michael Schlueter, Koichi Terasaka

Chemie Ingenieur Technik   2019

Research paper (scientific journal), Joint Work

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Synthesis, kinetic study, and reaction mechanism of Li₄SiO₄ with CO₂ in a slurry bubble column reactor

Kanai Y., Terasaka K., Fujioka S.

Chemical Engineering Communications (Chemical Engineering Communications)  207 ( 5 ) 598 - 611 2019

ISSN  00986445

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© 2019, © 2019 Taylor & Francis Group, LLC. This study was performed to investigate the synthesis, kinetic and reaction mechanism of Li 4 SiO 4 with CO 2 in a slurry bubble column reactor. The Li 4 SiO 4 powder sample was prepared via a solid-state reaction. The sample was characterized via X-ray diffraction (XRD) analysis and verified as a single phase. The median diameter of the sample was measured using the laser diffraction and scattering method as about 20 μm. The synthesized sample was suspended in binary molten carbonate of Li 2 CO 3 –K 2 CO 3 having a molar ratio of 38:62. The experimental results show that Li 4 SiO 4 in the slurry bubble column absorbed approximately a stoichiometric amount of CO 2 . The kinetic study shows that the CO 2 reaction behavior on the Li 4 SiO 4 surface was fitted to a double exponential model and the limiting step of the reaction was lithium diffusion. The mass transfer coefficient of CO 2 and rate constant of reaction with Li 4 SiO 4 were studied to understand the overall absorption mechanism in the reactor. The resistance for the direct reaction of CO 2 on the Li 4 SiO 4 was much smaller than the resistance for the mass transfer of CO 2 to the Li 4 SiO 4 . We can conclude that the direct contact of CO 2 with Li 4 SiO 4 was the main path for the reaction.

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ファインバブルテクノロジーの発展と展望

Terasaka Koichi

粉体技術 (一般社団法人日本粉体工業技術協会)  10 ( 11 ) 44 - 48 2018.11

Research paper (scientific journal), Single Work,  ISSN  1883-3292

Research on Cleaning and Purification Using Fine Bubbles

#HTakashi Hata, Yusuke Nishiuchi, Katsuya Tanaka, Yuriko Okamura, Yasushi Sakakibara, Koichi Terasaka

Japanese Journal of Multiphase Flow (The Japanese Society for Multiphase Flow)  32 ( 1 ) 4 - 11 2018

Research paper (scientific journal), Joint Work

超音波刺激によるウルトラファインバブルからマイクロバブルへの変化

Terasaka Koichi

日本ソノケミストリー 11 ( 1 ) 1 - 8 2017.03

The Establishment of Experimental Method to Observe Bubble Formation in High Temperature Molten Salt System and Estimation of Generated Bubble Size

Y. Kanai, K. Terasaka, S. Fujioka and K. Suzukawa J. Chem. Eng. Japan, Vol.50(2), pp.86-93 (2017)

J. Chem. Eng. Japan (J. Chem. Eng. Japan)  50 ( 2 ) 86 - 93 2017.02

Research paper (scientific journal), Joint Work,  ISSN  0021-9592

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Smaller Bubble Formation from a Horizontally Oscillation Nozzle

Daijiro MurakamiKoichi Terasaka, Satoko Fujioka

Japanese Journal of Multiphase Flow (The Japanese Society for Multiphase Flow)  31 ( 4 ) 422 - 426 2017

Research paper (scientific journal), Joint Work

Mass Transfer from a Shrinking Single Microbubble Rising in Water

Motoki IwakiriKoichi Terasaka, Satoko Fujioka, Michael Schluter, Sven Kastens, Shunya Tanaka

Japanese Journal of Multiphase Flow (The Japanese Society for Multiphase Flow)  30 ( 5 ) 529 - 535 2017

Research paper (scientific journal), Joint Work

ファインバブルの現状と将来展望

Terasaka Koichi

Japanese Journal of Multiphase Flow (The Japanese Society for Multiphase Flow)  30 ( 1 ) 1 - 2 2016.03

Research paper (scientific journal), Single Work