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Hashimoto, Shunsuke*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Shibata, Kaoru; Yamada, Takeshi*
Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11
Times Cited Count：3 Percentile：27(Chemistry, Physical)Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO
) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO nanofluids.
6 rod bundleHan, X.*; Shen, X.*; Yamamoto, Toshihiro*; Nakajima, Ken*; Sun, Haomin; Hibiki, Takashi*
International Journal of Heat and Mass Transfer, 144, p.118696_1 - 118696_19, 2019/12
Times Cited Count：14 Percentile：62.14(Thermodynamics)Yamada, Ryohei; Odagiri, Taiki*; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*
Radiation Environment and Medicine, 8(1), p.21 - 25, 2019/02
We evaluate radon/thoron and its progeny concentration using passive-type monitors using CR-39 plates. After exposure, it is necessary to do chemical etching for CR-39 plates. In the present study, we considered shortening of chemical etching time for CR-39 and enlargement of the track diameter (i.e. etch pit diameter) aiming for introduction of automatic counting system in the future. Optimum conditions were determined by changing solution concentration, solution temperature and etching time. As a result, the optimized conditions (concentration, temperature and etching time) were determined to be 8 M NaOH solution, 75 degrees Celsius and 10 hours. This result of etching time showed that the chemical etching was completed in less than half of conventional etching time. Furthermore, it was suggested that shorter etching time would be possible if we do not consider the enlargement of conventional track diameter.
Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo
Nuclear Engineering and Design, 333, p.87 - 98, 2018/07
Times Cited Count：11 Percentile：32.69(Nuclear Science & Technology)Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo
International Journal of Heat and Fluid Flow, 67(Part A), p.168 - 184, 2017/10
Times Cited Count：16 Percentile：62.54(Thermodynamics)An experimental study on upward bubbly air-water flows in a vertical large-diameter square duct have been performed by mainly using four-sensor probes. Local measurements of interfacial area concentration (IAC), void fraction, 3D bubble velocity vector and bubble diameter at 3 axial positions were conducted. Although the interfacial area transport equation (IATE) and its bubble coalescence and breakup models have already played an important role in predicting the IAC in general two-phase flow fields, they are mainly developed based on the two-phase flow experimental data taken in round pipes or small diameter channels. To confirm their usability in large-diameter square duct, this study has evaluated the 1D one-group IATE with its 6 sets of bubble coalescence and breakup models with the presently-obtained database. It was found the relative error between the best prediction and the database was 25%.
Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09
An experimental study on the upward bubbly air-water flows in a vertical large-diameter square duct have been performed by using four-sensor probes. The four-sensor probe were applied in the local measurements at 3 axial positions along the flow direction to obtain interfacial area concentration, 3-D bubble velocity vector and bubble diameter. The obtained void fraction, interfacial area concentration, 3-D bubble velocity vector and bubble diameter provided valuable insight into the flow structure and will serve as a valuable database to develop the mechanistic models for interfacial area transport equation sources and sinks.
Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo
Proceedings of 2017 Japan-US Seminar on Two-Phase Flow Dynamics (JUS 2017), 6 Pages, 2017/06
Ono, Ayako; Tanaka, Masaaki; Kobayashi, Jun; Kamide, Hideki
Mechanical Engineering Journal (Internet), 4(1), p.16-00217_1 - 16-00217_15, 2017/02
In the design of the Advanced Sodium-cooled Fast Reactor in Japan, the Reynolds number in the primary hot leg (H/L) piping reaches 4.210
. Furthermore, a short elbow is used in the H/L piping to achieve a compact plant layout. In the H/L piping, flow-induced vibration is a concern due to the excitation force caused by pressure fluctuation in the short elbow. In this report, the influence of inlet velocity condition on the unsteady velocity characteristics in the short elbow was studied by controlling the flow patterns at the elbow inlet. Measured velocity distributions indicated that the inlet velocity profiles affected a circumferential secondary flow, which then affected an area of flow separation at the elbow. It was also found that the velocity fluctuation at low frequency components observed upstream of the elbow could remain in downstream of the elbow though its intensity was attenuated.
Nakayama, Masashi; Matsuzaki, Tatsuji*; Niunoya, Sumio*
JAEA-Research 2016-010, 57 Pages, 2016/08
JAEA-Research-2016-010.pdf:10.81MB
JAEA-Research-2016-010-appendix(CD-ROM).zip:31.42MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal -Hydrological - Mechanical - Chemical coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. In this report, It is summarized the production of casing drilling machine for large diameter, simulated overpack, buffer material blocks and backfilling material for EBS experiment.
Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo
Progress in Nuclear Energy, 89, p.140 - 158, 2016/05
Times Cited Count：22 Percentile：88.83(Nuclear Science & Technology)An experimental study was performed on the local structure of upward air-water two-phase flow in a vertical large diameter square duct by using a four-sensor probe. The four-sensor probe method classifying spherical and non-spherical bubbles was applied as a key measurement way to obtain local parameters such as 3-D bubble velocity vector, bubble diameter and interfacial area concentration. Both the local void fraction and interfacial area concentration indicated radial core-peak and wall-peak distributions at low and high liquid flow rates respectively. The 2 components of the bubble velocity vector in the cross-section revealed that there exists a rotating secondary flow in the octant symmetric triangular area and the magnitude of the rotating secondary flow increases with the liquid flow rate. Some of constitutive correlations of drift-flux model and interfacial area concentration are reviewed to study their predictabilities against the present data.
Shahat, A.*; Awual, M. R.; Khaleque, M. A.*; Alam, M. Z.*; Naushad, M.*; Chowdhury, A. M. S*
Chemical Engineering Journal, 273, p.286 - 295, 2015/08
Times Cited Count：293 Percentile：99.54(Engineering, Environmental)Ono, Ayako; Tanaka, Masaaki; Kobayashi, Jun; Kamide, Hideki
Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 7 Pages, 2014/11
Kasahara, Mikio*; Ma, C.-J.*; Okumura, Motonori*; Kojima, Takuji; Hakoda, Teruyuki; Sakai, Takuro; Arakawa, Kazuo
JAERI-Review 2003-033, TIARA Annual Report 2002, p.270 - 272, 2003/11
A snow crystal scavenges earozol particles and trasfer various elements in atomosphere through heterogenious nucleation. The snow has many complicated crystal shapes which results in difficulty in comparison of its environmental purification function directly with that of raindrops. The replica of individual snow crystal grain was prepared by their immobilization on the collodion film. The replica samples were analized by micro-PIXE at JAERI and PIXE st Kyoto university. The following results are obtained: (1) Size(circumscribed diameter) of individual snow crystal are in the range of 0.12-2.5mm, (2)snow crystal grows from hexagnal plate to dendritic sectored plate, (3) major elements captured by a snow crystal are Si,S,K,Ca,Fe,S, (4)there is relation between snow crystal size and captured-element masses. The result leads us to presume the chemical inner-structure and the elemental mixing state in/on single snow crystal.
Onuki, Akira; Akimoto, Hajime
Journal of Nuclear Science and Technology, 38(12), p.1074 - 1080, 2001/12
Multi-dimensional analyses have been expected recently with expanding computation resources for gas-liquid two-phase flow analyses of advanced nuclear systems such as passive safety systems and natural-circulation-type reactors. However, the applicability of previous constitutive equations for multi-dimensional analyses has not been fully investigated especially for the effects of flow path scale because the equations have been assessed for small-scale experiments. In this study, we analyzed the scale effects by the multi-dimensional two-fluid model code using data in 38 mm and 200 mm diameter pipes. We clarified a key-parameter to model the scale effects and developed models for the effects on phase distribution. The scale effects can be classified by the relative relationship between bubble diameter db and turbulent length scale lT. Bubble-induced turbulence is increased under that db is smaller than lT and bubble coalescence is predominated rather than breakup under that lT is about three times larger than db and under higher void fraction. Based on these findings, we established new models for bubble turbulent diffusion and bubble diameter. The applicability was promising through assessments against the 38 mm and 200 mm pipes under different flow rates and against a database for developing flow along 480 mm pipe.
Onuki, Akira; Akimoto, Hajime
Proceedings of the 8th International Symposium on Flow Modeling and Turbulence Measurements (FMTM2001) (CD-ROM), 7 Pages, 2001/12
Multi-dimensional analyses have been expected with expanding computation resources for gas-liquid two-phase flow. We recently developed models for bubble turbulent diffusion and bubble diameter to predict the phase distribution by a multi-dimensional two-fluid model. This study was performed to verify our model. The verification was performed using databases under diameter; 9 mm to 155 mm, pressure; atmospheric to 4.9 MPa, flow rate; superficial gas velocity = 0.01 to 5.5 m/s and superficial liquid one = 0.0 to 4.3 m/s, fluid combination; air-water or steam-water. Through the assessments, our model was found to be applicable to the wide range of flow conditions including the effect of pipe diameter. The shape of phase distribution and the average void fraction are predicted well qualitatively and quantitatively. Since the model is established using the ratio of bubble diameter to eddy size as a key-parameter, the ratio is one of important parameters to develop the constitutive equations in the multi-dimensional two-fluid model.
Onuki, Akira; Akimoto, Hajime
International Journal of Multiphase Flow, 26(3), p.367 - 386, 2000/03
Times Cited Count：130 Percentile：95.99(Mechanics)no abstracts in English
Onuki, Akira; *; Akimoto, Hajime
Konsoryu Shimpojiumu '98 Koen Rombunshu, p.221 - 222, 1998/00
no abstracts in English
Onuki, Akira; Akimoto, Hajime
Proc. of 1st European-Japanese Two-phase Flow Group Meeting, p.1 - 8, 1998/00
no abstracts in English
Onuki, Akira; Akimoto, Hajime
Proc. of 3rd Int. Conf. on Multiphase Flow (ICMF'98), p.1 - 6, 1998/00
no abstracts in English
; Kumamaru, Hiroshige; Murata, Hideo; Kukita, Yutaka
JAERI-Research 96-038, 55 Pages, 1996/07
JAERI-Research-96-038.pdf:1.63MB
no abstracts in English
