著者

岩本 頌平 兒玉 学 原田 祥宏 加藤 弘一 門永 雅史 伏信 一慶 平井 秀一郎

出版者

一般社団法人 日本画像学会

雑誌

日本画像学会誌 (ISSN:13444425)

巻号頁・発行日

vol.61, no.2, pp.98-104, 2022-04-10 (Released:2022-04-10)

参考文献数

10

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インクジェットプリンティングにおけるインクの浸透は画質ならびに乾燥効率に関与することから,浸透挙動の把握は重要である.本研究では,コート層の構造 (コート層の有無と層数と厚さ) による液滴の浸透挙動の解明を目的として,コート層のない紙1種とコート層のある紙3種に対して,X線CT (computed tomography) による非破壊浸透域計測,SEM (scanning electron microscope) 断面観察による紙構造計測,浸透の準2次元数値解析を実施した.臭化カリウムを溶質とする水性インクを用いることで,液滴の浸透域のX線CT測定を可能とし,得られた液滴浸透域と断面SEMにより計測された紙構造を比較した.その結果,コート層の有無,コート層の層数・空隙径・厚さが浸透に影響することが明らかとなり,特にコート層が2層構造をなす場合,表側コート層にのみ液滴が浸透することが明らかとなった.また数値解析の結果,この表側コート層への浸透は,表側コート層の細孔径が裏側コート層の細孔径よりも小さいことが原因であることが示された.

著者

兒玉 学 松前 光 木内 豪士 村上 直紀 平井 秀一郎

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.141, no.7, pp.541-546, 2021-07-01 (Released:2021-07-01)

参考文献数

18

被引用文献数

1 3

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Three-dimensional large scale magnetohydrodynamic, two-phase flow, and electrochemical reaction coupling numerical simulations of alkaline water electrolysis with magnetic field were conducted to elucidate the bubble-bubble interaction and the influence of that on the overpotential. Numerical results shown that the magnetic field enhances the coalesce of bubbles and the bubble size was increased with the increase in the magnetic flux density. Moreover, the magnetic field suppressed the cell overpotential by suppressing the anode overpotential and ohmic overpotential. This is because, KOH concentration around the anode is increased by mixing of the electrolyte, and the reduction of the shielding effect by coalescing of the bubbles.

著者

兒玉 学 平井 秀一郎

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.142, no.3, pp.199-204, 2022-03-01 (Released:2022-03-01)

参考文献数

12

被引用文献数

2

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Applying a magnetic field to a water electrolyzer is one of the methods to improve energy conversion efficiency from electrical energy to hydrogen energy. In this study, experiments of alkaline water electrolysis with a magnetic field are carried out to elucidate the influence of a magnetic field direction and a magnetic flux density on cell voltage and bubble movement. In the case with B⊥electrode, the cell voltage decreases with the increase in current density and magnetic flux density, because the bubbles are removed from the electrode and the electrolyte is mixed with Lorentz-force. In the case with B∥electrode, the cell voltage is suppressed in low current density conditions. However, in high current density conditions, the bubbles are trapped in the electrolyte and the cell voltage is increased.

著者

兒玉 学 戸瀬 義久 奥村 一彦 平井 秀一郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.86, no.892, pp.20-00183, 2020 (Released:2020-12-25)

参考文献数

16

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Electrolyzed water generator can produce acidic and alkaline water from tap water and electric power, and is expected to have applications in the food and medical fields for sterilization, cleaning and disinfection. However, there are still many unknowns about the internal phenomena of the electrolytic water production system, especially the two-dimensional phenomena that have a strong influence on the miniaturization, power saving, and longevity of the electrolyzed water generator. In this study, multi physics modeling of electrolyzed water generator and two-dimensional numerical simulations are conducted to elucidate the fluid, electrochemical, and electrical phenomena in an electrolyzed water generator. The numerical model is built with governing equations from fluid dynamics, electrochemistry, and electrodynamics. The results show that the neutralization reaction with hydrogen carbonate (HCO3-) is an important reaction in electrolyzed water generator, and this reaction divides the anode cell into two regions (low pH region and high pH region), and the electrical conductivity is low in the low pH region. This region with low pH and electrical conductivity extends to the mainstream direction. The current density on the upstream of anode is higher than that of the downstream of anode. This occurs since the region with low electrical conductivity becomes increasingly thicker moving downstream.

著者

兒玉 学 木内 豪士 鳥居 健次郎 平井 秀一郎

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.140, no.7, pp.617-622, 2020-07-01 (Released:2020-07-01)

参考文献数

16

被引用文献数

3 5

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Three dimensional magnetohydrodynamic, two-phase flow and electrochemical reaction coupling numerical simulation of alkaline water electrolysis with magnetic field is conducted to estimate and reveal the mechanism of overvoltage suppression with the magnetic field. The numerical results shown that both vertical magnetic field to the electrode and parallel magnetic field to the electrode suppress the overpotential by the mixing of the electrolyte. This mixing is induced by the secondary flow in both cases. The overvoltage suppression is constantly increased with the increase in magnetic flux density in the case with parallel magnetic field, however, that is saturates in the case with vertical magnetic field to the electrode due to the bubble position is changed by the flow.

著者

兒玉 学 鳥居 健次郎 平井 秀一郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.86, no.883, pp.19-00354, 2020 (Released:2020-03-25)

参考文献数

17

被引用文献数

2 1

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In this paper, two-phase flow and ion transportation in an alkaline water electrolysis are discussed with three-dimensional coupling numerical simulation to reveal the influence of a bubble in the alkaline water electrolysis on the cell efficiency to achieve high-efficiency energy conversion of electrical energy to hydrogen energy. Two-phase flow numerical simulation model is not a void ratio model that is mainly used in previous studies, but is a direct simulation model with Lattices Kinetic Scheme that enables microscale flow simulation. Moreover, the concentration distribution is calculated with Maxwell equation and Nernst-Planks equation, and is fully coupled to the three-dimensional two-phase flow. The numerical simulations are conducted for w/o bubble condition and w/ bubble condition with varying applied current density to evaluate the influence of a bubble at various operating conditions. The results show that the bubble in the electrolyte induces mixing flow between a bubble and an electrode, and the concentration of potassium hydroxide (KOH) around the anode is increased. This increase of concentration increases the conductivity of the electrolyte and suppresses the overpotential in the electrolyte. Moreover, the anodic activation overpotential is also suppressed by the increased concentration on the anode. These overvoltage suppressions become much more prominent at high current density operating condition of the cell. The mixing with the bubble changes the concentration around the bubble. However, concentration distant from the bubble also changes and suppresses the overpotential with the change in electrical field.

著者

兒玉 学 戸瀬 義久 奥村 一彦 平井 秀一郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

pp.20-00183, (Released:2020-11-13)

参考文献数

16

---

Electrolyzed water generator can produce acidic and alkaline water from tap water and electric power, and is expected to have applications in the food and medical fields for sterilization, cleaning and disinfection. However, there are still many unknowns about the internal phenomena of the electrolytic water production system, especially the two-dimensional phenomena that have a strong influence on the miniaturization, power saving, and longevity of the electrolyzed water generator. In this study, multi physics modeling of electrolyzed water generator and two-dimensional numerical simulations are conducted to elucidate the fluid, electrochemical, and electrical phenomena in an electrolyzed water generator. The numerical model is built with governing equations from fluid dynamics, electrochemistry, and electrodynamics. The results show that the neutralization reaction with hydrogen carbonate (HCO3-) is an important reaction in electrolyzed water generator, and this reaction divides the anode cell into two regions (low pH region and high pH region), and the electrical conductivity is low in the low pH region. This region with low pH and electrical conductivity extends to the mainstream direction. The current density on the upstream of anode is higher than that of the downstream of anode. This occurs since the region with low electrical conductivity becomes increasingly thicker moving downstream.