Development of a dynamic CT system for neutron radiography and consecutive visualization of three-dimensional water behavior in a PEFC stack

Murakawa, Hideki*; Hashimoto, Michinori*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Mochiki, Koichi*; Yasuda, Ryo

Nihon Kikai Gakkai Rombunshu, B, 77(784), p.2255 - 2262, 2011/12

https://doi.org/10.1299/kikaib.77.2255

Evaluation of water distribution in a small operating fuel cell using neutron color image intensifier

Yasuda, Ryo; Nitto, Koichi*; Konagai, Chikara*; Shiozawa, Masahiro*; Takenaka, Nobuyuki*; Asano, Hitoshi*; Murakawa, Hideki*; Sugimoto, Katsumi*; Nojima, Takehiro; Hayashida, Hirotoshi; et al.

Nuclear Instruments and Methods in Physics Research A, 651(1), p.268 - 272, 2011/09

https://doi.org/10.1016/j.nima.2011.01.175

Neutron radiography is one of useful tools to visualize water behavior in fuel cells under operation. In order to observe the detailed information about the water distribution in MEA and GDL in fuel cells, a high spatial resolution and high sensitivity neutron imaging system are required. We developed an imaging system using the neutron color imaging intensifier and continuously observed water distribution in operating a fuel cell. By using the system, a small type fuel cell under operation was continuously observed at the TNRF in every 20 sec. In the results, the water area was appeared from GDL and MEA, and expanded to the channel of the cathode side. On the other hand, voltage was gradually reduced with the operation time, and steeply dropped. It is considered that voltage drop was caused by blockage of gas flow due to the piling up water in the channel of the cathode side.

Effect of water distributions on performances of JARI standard PEFC by using neutron radiography

Murakawa, Hideki*; Ueda, Tadanobu*; Yoshida, Takehisa*; Sugimoto, Katsumi*; Asano, Hitoshi*; Takenaka, Nobuyuki*; Mochiki, Koichi*; Iikura, Hiroshi; Yasuda, Ryo; Matsubayashi, Masahito

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.127 - 130, 2009/06

https://doi.org/10.1016/j.nima.2009.01.142

Flow behaviors and void fraction distribution in mini-channel cross-flow vaporizer

Kiyohara, Keita*; Murakawa, Hideki*; Sugimoto, Katsumi*; Kubo, Yohei*; Kurita, Keisuke; Iikura, Hiroshi; Asano, Hitoshi*

no journal, , 

Boiling two-phase flows in mini-channel cross-flow vaporizer had been visualized by two methods, neutron radiography and the method by replacing the outer wall with a transparent wall.

Stabilization methods for the inverse problem in ultrasonic measurement of microbubble distributions in liquids

Kagi, Eiji*; Sugimoto, Katsumi*; Abe, Yuta; Aizawa, Kosuke; Murakawa, Hideki*

no journal, , 

In sodium-cooled fast reactors (SFRs), non-condensable gases in the primary sodium coolant may be transported as small bubbles through the cooling circuit, resulting in disturbances in core reactivity. Therefore, it is necessary to establish numerical codes that can accurately predict the behavior of bubbles in liquid sodium. To validate the analytical results, an experimental evaluation of the void fraction and number of bubbles is crucial. However, the measurement technique is limited to opaque liquid sodium. In this study, an acoustic bubble spectrometer (ABS) was employed to measure the bubble size distribution using ultrasound and acoustic emission (AE) sensors for the application to liquid sodium. For the ABS analysis, physical constraints such as the non-negativity of bubble size distributions and upper limits on the void fraction were applied. The ABS system was tested to measure the distribution of microbubbles in water. The results indicate that the ABS system can detect bubble size distributions on the order of several tens of micrometers, demonstrating the potential of applying the system under liquid-sodium conditions.