Iron and Steel Institute of Japan Acta Medica Okayama 0915-1559 65 13 2025 Heat Transfer Enhancement by Forming Bridges among Reactive Particles in a Packed Bed Reactor of a Solid-gas Chemical Heat Storage System 2097 2104 EN Koichi Nakaso Faculty of Environmental, Life Natural Science and Technology, Okayama University Kenji Shimada Graduate School of Natural Science and Technology, Okayama University Yasushi Mino Faculty of Environmental, Life Natural Science and Technology, Okayama University Kuniaki Gotoh Faculty of Environmental, Life Natural Science and Technology, Okayama University In this study, the enhancement of the thermal output of solid-gas chemical heat storage systems was investigated. Bridges made of high-thermal conductivity materials were formed among reactive particles by drying a slurry which contained graphite powder as a thermal additive and dispersant in a packed-bed reactor. First, the effect of the volume ratio of the dispersant on effective thermal conductivity was investigated. The optimum volume ratio of dispersant to graphite powder was determined. Furthermore, repetitive bridge formation increased the effective thermal conductivity. Based on these results, we investigated the thermal response of the energy-discharge process. Consequently, the temperature distribution in the radial direction of the reactor decreased owing to the formation of bridges. In addition, the thermal energy generated by the adsorption of water vapor onto the adsorbent was effectively transferred to the reactor wall. The thermal output was estimated based on the experimental results. The thermal output was increased by the formation of bridges. No potential conflict of interest relevant to this article was reported.

日本エアロゾル学会 Acta Medica Okayama 0912-2834 40 2 2025 水溶性高分子含有スラリー液滴乾燥過程の評価 99 108 EN Koichi Nakaso Faculty of Environmental, Life, Natural Science and Technology, Okayama University Daichi Yamashita Graduate School of Natural Science and Technology, Okayama University Yutaro Aoyama Graduate School of Natural Science and Technology, Okayama University Yasushi Mino Faculty of Environmental, Life, Natural Science and Technology, Okayama University Kuniaki Gotoh Faculty of Environmental, Life, Natural Science and Technology, Okayama University The granulation process of a slurry droplet containing a water-soluble polymer in a spray dryer is investigated. Although there have been many studies on the drying behavior of a single-component slurry droplet, there have been few reports for a multicomponent slurry droplet. This is due to the complexity and difficulty in evaluating the drying behavior of a multicomponent slurry droplet. Therefore, for the production of granules from multicomponent materials by a spray dryer, its operating conditions are usually determined by trial and error. To optimize the practical granule production process, the drying behavior of multicomponent slurry droplets should be studied. In this study, the drying behavior of a silica slurry droplet containing polyvinyl alcohol (PVA) is investigated. The drying behavior of a droplet suspended on the tip of a needle was observed. The effect of the volume fraction of PVA on the drying behavior and the morphology of a dried granule is studied. The effect of drying condition on the granule formation process is also investigated. As a result, the structure of dried granules was strongly influenced by PVA concentration. Segregation of PVA in the dried granules was observed. Based on the results, the drying process diagram is presented. No potential conflict of interest relevant to this article was reported.

American Physical Society (APS) Acta Medica Okayama 2470-0045 105 4 2022 Lattice Boltzmann model for capillary interactions between particles at a liquid-vapor interface under gravity 045316 EN Yasushi Mino Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hazuki Tanaka Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Koichi Nakaso Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Kuniaki Gotoh Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hiroyuki Shinto Department of Chemical Engineering, Fukuoka University A computational technique based on the lattice Boltzmann method (LBM) is developed to simulate the wettable particles adsorbed to a liquid-vapor interface under gravity. The proposed technique combines the improved smoothed-profile LBM for the treatment of moving solid particles in a fluid and the free-energy LBM for the description of a liquid-vapor system. Five benchmark two-dimensional problems are examined: (A) a stationary liquid drop in the vapor phase; a wettable particle adsorbed to a liquid-vapor interface in (B) the absence and (C) the presence of gravity; (D) two freely moving particles at a liquid-vapor interface in the presence of gravity (i.e., capillary flotation forces); and (E) two vertically constrained particles at a liquid-vapor interface (i.e., capillary immersion forces). The simulation results are in good quantitative agreement with theoretical estimations, demonstrating that the proposed technique can reproduce the capillary interactions between wettable particles at a liquid-vapor interface under gravity. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2470-0045 101 3 2020 Lattice Boltzmann method for simulation of wettable particles at a fluid-fluid interface under gravity 033304 EN Yasushi Mino Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hiroyuki Shinto Department of Chemical Engineering, Fukuoka University A computational technique was developed to simulate wettable particles trapped at a fluid-fluid interface under gravity. The proposed technique combines the improved smoothed profile-lattice Boltzmann method (iSP-LBM) for the treatment of moving solid-fluid boundaries and the free-energy LBM for the description of isodensity immiscible two-phase flows. We considered five benchmark problems in two-dimensional systems, including a stationary drop, a wettable particle trapped at a fluid-fluid interface in the absence or presence of gravity, two freely moving particles at a fluid-fluid interface in the presence of gravity (i.e., capillary floatation forces), and two vertically constrained particles at a fluid-fluid interface (i.e., capillary immersion forces). The simulation results agreed well with theoretical estimations, demonstrating the efficacy of the proposed technique. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2470-0045 95 4 2017 Effect of internal mass in the lattice Boltzmann simulation of moving solid bodies by the smoothed-profile method 043309 EN Yasushi Mino Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hiroyuki Shinto Department of Chemical Engineering, Fukuoka University Shohei Sakai Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University Hideto Matsuyama Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University A computational method for the simulation of particulate flows that can efficiently treat the particle-fluid boundary in systems containing many particles was developed based on the smoothed-profile lattice Boltzmann method (SPLBM). In our proposed method, which we call the improved SPLBM (iSPLBM), for an accurate and stable simulation of particulate flows, the hydrodynamic force on a moving solid particle is exactly formulated with consideration of the effect of internal fluid mass. To validate the accuracy and stability of iSPLBM, we conducted numerical simulations of several particulate flow systems and compared our results with those of other simulations and some experiments. In addition, we performed simulations on flotation of many lightweight particles with a wide range of particle size distribution, the results of which demonstrated the effectiveness of iSPLBM. Our proposed model is a promising method to accurately and stably simulate extensive particulate flows. No potential conflict of interest relevant to this article was reported.