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.