研究者詳細 - 堀部　明彦

論文 - 堀部　明彦

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Effect of Droplet-Removal Processes on Fog-Harvesting Performance on Wettability-Controlled Wire Array with Staggered Arrangement 査読

Yutaka Yamada, Junya Oka, Kazuma Isobe, Akihiko Horibe

Langmuir 40 ( 32 ) 16994 - 17000 2024年7月

Heat-transfer characteristics of the two-phase-change process between a microencapsulated phase-change-material-slurry droplet and air: A numerical study 査読

Zhengyin Yuan, Akihiko Horibe, Wael I.A. Aly, Kunfeng Liang, Yutaka Yamada, Kazuma Isobe

International Communications in Heat and Mass Transfer 155 107497 - 107497 2024年6月

Bayesian optimization of periodic multilayered slabs for passive absorptivity control 査読

Kazuma Isobe, Tsuyoshi Yamamoto, Yutaka Yamada, Akihiko Horibe

International Journal of Heat and Mass Transfer 221 125047 - 125047 2024年4月

Melting and Solidification Characteristic of Mixture of Two Types of Latent Heat Storage Material in Direct Contact Heat Exchanger 査読

JikSu Yu, Akihiko Horibe, Naoto Haruki

Experimental Heat Transfer 1 - 21 2024年2月

Radiative energy transfer via surface plasmon polaritons around metal–insulator grating: For better understanding of magnetic polariton 査読

Kazuma Isobe, Yutaka Yamada, Akihiko Horibe, Katsunori Hanamura

Journal of Thermal Science and Technology 19 ( 1 ) 2024年

掲載種別：研究論文（学術雑誌）

A conventional metal–insulator nanograting has the potential to transmit near-infrared thermal radiation because an electromagnetic wave is resonated in the grating structure. Surface plasmon polaritons (SPPs) take place at the interface between the metal and the insulator with boundaries at both ends. Physicists formulated the resonance frequency of the grating from the Fabry–Pérot interference between the grating thickness and the wavelength of SPPs in a short-range coupled mode. On the other hand, engineering researchers often use a lumped-element model assuming a resonant circuit consisting of an inductance of metal and a capacitance of metal-insulator-metal grating structure. Furthermore, they have considered that the resonant circuit excites a strong magnetic field independent of SPPs. This study compares each physical model and numerical simulation results, then clearly shows that all resonance frequencies and features of the circuit resonance can be described by the Fabry–Pérot interference of the SPPs in short-range coupled mode. Moreover, the estimated resonance frequencies obviously correspond to the local maxima of the transmittance of the nanograting with the various thicknesses and pitches. In this case, a strong magnetic field can be observed in the insulator layer as if it might be an isolated magnetic quantum. However, since materials show no magnetism at near-infrared frequencies, the magnetic response appears due to the contribution of SPPs.

DOI： 10.1299/jtst.23-00531

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相変化蓄冷材としての潜熱エマルションの生成と物性測定査読

松﨑駿, 堀部明彦, 山田寛, 磯部和真

日本冷凍空調学会論文集 advpub 2024年

記述言語：日本語出版者・発行元：公益社団法人日本冷凍空調学会

<tt>本研究では</tt>0 ℃<tt>以下の温度域において流動性を保持しながら潜熱の吸収，放出が可能な相変化蓄冷材の生成を目標とし，分散媒として濃度</tt>50 mass%<tt>のエチレングリコール水溶液を，相変化物質として融点</tt>-9.6 ℃<tt>の</tt>Dodecane <tt>を採用した潜熱エマルションを生成した．実験の結果，界面活性剤としてポリオキシエチレン</tt>(20)<tt>ソルビタンモノオレエートとソルビタンモノオレエートを採用し</tt>D <tt>相乳化法を用いることにより，平均粒子径が</tt>0.24 μm <tt>程度の微細な</tt>Oil-in-water <tt>エマルションの生成が可能と判明した．試作試料の評価実験を行った結果，長期間乳化状態を維持し，相変化物質が凝固した状態でも流動性を保持することが可能であるということが明らかになった．また，示差走査熱量計による測定結果より，</tt>60 mJ/mg <tt>程度の融解潜熱を有すると判明した．</tt>

DOI： 10.11322/tjsrae.23-26_oa

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Water/ice mixture- and freezing-front motion in a non-isothermal liquid bridge 査読

Yutaka Yamada, Kodai Okano, Kazuma Isobe, Akihiko Horibe

Applied Physics Letters 123 ( 23 ) 2023年12月

掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Publishing

We experimentally investigate the water/ice mixture- and freezing-front behavior in a water liquid bridge under isothermal and non-isothermal conditions. We find rapid propagation, temporary suspension, and regression of the water/ice mixture front, and finally, it merges with the freezing front when part of the liquid bridge is higher than the freezing temperature. However, freezing-front propagation follows dendritic ice formation, and a protrusion forms at the middle of the liquid bridge as long as the whole liquid bridge is lower than the freezing temperature. We explain those phenomena by quasi-stationary heat-transfer considerations.

DOI： 10.1063/5.0167486

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Analysis of Evaporation of Droplet Pairs by a Quasi-Steady-State Diffusion Model Coupled with the Evaporative Cooling Effect 査読

Yutaka Yamada, Kazuma Isobe, Akihiko Horibe

Langmuir 39 ( 44 ) 15587 - 15596 2023年11月

掲載種別：研究論文（学術雑誌）

Multidroplet evaporation is a common phase-change phenomenon not only in nature but also in many industrial applications, including inkjet printing and spray cooling. The evaporation behavior of these droplets is strongly affected by the distance between neighboring droplets, and in particular, evaporation suppression occurs as the distance decreases. However, further quantitative information, such as the temperature and local evaporation flux, is limited because the analytical models of multidroplet evaporation only treat vapor diffusion, and the effect of the latent heat transfer through the liquid-vapor phase change is ignored. Here, we perform a numerical analysis of evaporating droplet pairs that linked vapor diffusion from the droplet surface and evaporative cooling. Heat transfer through the liquid and gas phases is also considered because the saturation pressure depends on the temperature. The results show an increase in the vapor concentration in the region between the two droplets. Consequently, the local evaporation flux in the proximate region significantly decreases with decreasing separation distance. This means that the latent heat transfer through the phase change is diminished, and an asymmetrical temperature distribution occurs in the liquid and gas phases. These numerical results provide quantitative information about the temperature and local evaporation flux of evaporating droplet pairs, and they will guide further investigation of multiple droplet evaporation.

DOI： 10.1021/acs.langmuir.3c01893

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Natural convective heat transfer from a heated horizontal disc with heated hollow cylinders: Effect of flow characteristics around heated cylinders with a gap 査読

Rikio Shimoyama, Yutaka Yamada, Kazuma Isobe, Akihiko Horibe

International Communications in Heat and Mass Transfer 146 2023年7月

掲載種別：研究論文（学術雑誌）

The natural convective heat transfer from a heated horizontal disc with gapped heated hollow cylinders was investigated experimentally, forming the foundation for improving the cooling performance of the heat sinks. The cooling target for this study was the central area of the heated horizontal disc where the heat dissipation was low. The heat transfer was greatly enhanced by the reversal of the flow from the gap between the heated hollow cylinders towards the heated horizontal disc. The reverse flow was promoted by the conditions of a narrow clearance between the heated horizontal disc and the heated hollow cylinder and a wide gap between the heated hollow cylinders. Conversely, for the flow along the heated horizontal disc, the heat transfer showed improvement by increasing the clearance between the heated horizontal disc and the heated hollow cylinder. The relationship between the heat transfer and flow properties was demonstrated using the Nusselt number of the heated horizontal disc and the Rayleigh number corrected for the ratio of the heated hollow cylinder height to the clearance between the heated horizontal disc and the heated hollow cylinder.

DOI： 10.1016/j.icheatmasstransfer.2023.106928

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Synthesis and Characterization of Silica-Encapsulated n-Tetracosane and the Effect of Surface Modification by Silane Coupling Agents 査読

Kyosuke Okuno, Kazuma Isobe, Akihiko Horibe, Yutaka Yamada

International Journal of Thermophysics 44 ( 5 ) 2023年5月

掲載種別：研究論文（学術雑誌）

Microencapsulation of n-tetracosane, whose melting point is approximately 50 °C, in a silica shell has been performed through the sol–gel method using tetraethyl orthosilicate (TEOS) as the precursor for silica-shell formation. Additionally, two types of silane coupling agents were used to modify the surface of the microcapsules to change the wettability. The morphology of the microcapsules was observed by scanning electron microscopy. The chemical composition was characterized by Fourier transform infrared spectroscopy. The results confirmed the presence of n-tetracosane and silica in the synthesized microcapsules. Wettability analysis showed hydrophobic and hydrophilic features because of the added silane coupling agents. From the results of differential scanning calorimetry measurements, the encapsulation ratio of the microcapsules increased with decreasing TEOS/n-tetracosane ratio, and the highest encapsulation ratio was 87.1 % at a TEOS/n-tetracosane ratio of 0.25. The pH in the microcapsule solution was affected by addition of a silane coupling agent, and shifting the pH to the basic side lowered the encapsulation ratio owing to enhancement of silica condensation. After 100 differential scanning calorimetry cycles, there was no significant degradation in the phase-change temperatures and enthalpies, which confirmed the good phase-change stability and repeatability. Therefore, the microcapsules are a potential material for thermal-energy-storage systems to effectively utilize energy.

DOI： 10.1007/s10765-023-03179-1

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Thermal Energy Storage Performance Enhancement of Microencapsulated n-Tetracosane with a Polymorph-Modulated Calcium Carbonate Shell 査読

Yutaka Yamada, Takeru Sato, Kazuma Isobe, Wael I.A. Aly, Akihiko Horibe

Energy and Fuels 37 ( 4 ) 3152 - 3158 2023年2月

掲載種別：研究論文（学術雑誌）

Microencapsulated n-tetracosane as a phase change material with an inorganic calcium carbonate (CaCO3) shell has been synthesized through a self-assembly process with varying pH value of a precursor solution, and the resultant materials were systematically investigated. Spherical microcapsules with a mean diameter of less than 3 μm were seen by microscopic observation. X-ray diffraction analysis revealed the presence of three CaCO3 polymorphs such as calcite, aragonite, and vaterite in the shell, and these compositions depended on the solution pH. This fact was also confirmed by Fourier transform infrared spectra and reflected in the surface morphology of microcapsules. The characterization of the phase change behavior has shown no significant change in the phase change temperatures and more than 170 mJ/mg of phase change enthalpies with the microcapsules synthesized at pH = 1. This enthalpy corresponds to 69.2% of encapsulation efficiency which is improved from the value reported by other microcapsules with CaCO3 shells. Thermal cycling analysis exhibited good reliability and durability of phase change phenomena in the long term. These results demonstrate a promising potential of microcapsules for developing thermal energy storage materials at a mild temperature range, which can be applied for waste heat recovery applications.

DOI： 10.1021/acs.energyfuels.2c03564

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Experimental evaluation of latent heat use of a microencapsulated phase change material slurry in spraying

Zhengyin Yuan, Akihiko Horibe, Kunfeng Liang, Yutaka Yamada, Kazuma Isobe, Yonghao Xue

International Journal of Heat and Mass Transfer 201 2023年2月

担当区分：責任著者掲載種別：研究論文（学術雑誌）

A spraying system was constructed with a microencapsulated phase change material (MPCM) slurry as the working medium to weaken the adverse effects of the slurry's high viscosity and low thermal conductivity on heat transfer in a wall tube heat exchanger. The temperature distributions of pure water and MPCM slurry were first obtained through infrared thermal imaging in spraying. Furthermore, the latent heat use of MPCM slurry was investigated through a new method based on the temperature properties of the phase change fluid, in which the working and phase change temperature ranges are matched. The heat-mass transfer characteristics are compared and discussed with those of the base fluid, and the latent heat use of 10wt% MPCM slurry containing the core material n-docosane (C22H46). The experimental results indicate that the phase change enables the MPCM slurry droplets to maintain a higher temperature than a fluid with no phase change or base fluid. Different application modes (static and spraying) have correspondingly different phase change temperature ranges owing to supercooling, and the degree of matching between the working and phase change temperature ranges has a critical impact on the latent heat use of the MPCM slurry. Finally, comparing the heat transfer coefficients and Lewis numbers between the base liquid and MPCM slurry reveals that the phase change not only enhances the heat transfer but also slightly reduces water evaporation compared with pure water spraying.

DOI： 10.1016/j.ijheatmasstransfer.2022.123573

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Droplet motion on a wrinkled PDMS surface with a gradient structural length scale shorter than the droplet diameter 査読

Yutaka Yamada, Kazuma Isobe, Akihiko Horibe

RSC Advances 12 ( 22 ) 13917 - 13923 2022年5月

掲載種別：研究論文（学術雑誌）

Droplet transportation using a wettability gradient surface has attracted much attention owing to applications such as in microfluidic devices. A surface with a spatial structural gradient was prepared through a simple and cost-effective process even though understanding of droplet behavior on the structure was still limited. Here, we report impinging droplet motion on a gradient wrinkled surface. Surfaces were prepared through hard film deposition on soft pre-strained polydimethylsiloxane (PDMS) with a mask installed with a slit to control the amount of deposition, which is related to the wavelength of the wrinkles. Droplets were impinged with varying position with respect to the structure, and the droplet motion was observed in the direction away from the region under the slit. We found an asymmetric contact angle and alternate motion on both sides of the three-phase contact line during the motion according to the gradient of the wrinkle wavelength. These results may help not only to understand the behavior of droplet impingement on a gradient structural surface but also to further develop applications using directional droplet transfer.

DOI： 10.1039/d1ra09244h

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Thermal Conductivity Estimation of Carbon-Nanotube-Dispersed Phase Change Material as Latent Heat Storage Material 査読

Shin-ichi Morita, Toshihiro Haniu, Kazunori Takai, Takanobu Yamada, Yasutaka Hayamizu, Takeshi Gonda, Akihiko Horibe, Naoto Haruki

International Journal of Thermophysics 43 ( 5 ) 2022年5月

Absorptivity Control Over the Visible to Mid-Infrared Range Using a Multilayered Film Consisting of Thermochromic Vanadium Dioxide 査読

Kazuma Isobe, Minoru Tomioka, Yutaka Yamada, Akihiko Horibe

International Journal of Thermophysics 43 ( 3 ) 2022年3月

Experimental study of evaluation of dynamical utilization of a microencapsulated phase change material slurry based on temperature range matching analysis

Zhengyin Yuan, Kunfeng Liang, Yonghao Xue, Yutaka Yamada, Kazuma Isobe, Akihiko Horibe

International Communications in Heat and Mass Transfer 130 2022年1月

担当区分：最終著者掲載種別：研究論文（学術雑誌）

Microencapsulated phase change material (MPCM) slurries are energy-carrier fluids. Their latent heat utilization has been investigated by a new method based on the temperature properties of the phase-change fluid, in which match of the working and phase-change temperature ranges is considered. Based on the working-temperature range (3–15 °C) in heat-exchange circulation, the dynamic heat-transfer characteristics and utilization of the MPCM slurry with the core material n-docosane (C22H46) are discussed. The experimental results indicate that the effects of the stirring rate and flow rate on the dynamic heat-transfer characteristics are similar to those of water, and they have little influence on utilization of the 10% MPCM slurry, whereas the corresponding effect of the concentration is relatively large. When investigating the effect of the concentration, it was found that a low phase-change ratio suppressed movement of the phase-change-temperature range owing to the residual solid core material acting as a crystal nucleus, while the heat-transfer performance and latent heat utilization of the MPCM slurry suppressed each other. The 10% MPCM slurry is the most suitable energy carrier fluid, but supercooling still needs to be resolved. The experimental results provide a reference for practical efficient application of MPCM slurries as energy carrier fluids.

DOI： 10.1016/j.icheatmasstransfer.2021.105788

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コンピュータグラフィックソフトを応用したふく射の指向性の汎用的評価手法査読

磯部和真, 山田寛, 堀部明彦

日本伝熱学会論文集 30 ( 2 ) 23 2022年