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Journal Articles

Sea water flow boiling heat transfer involving sea salt deposition; Role of deposited sea salt

Koizumi, Yasuo*; Uesawa, Shinichiro; Ono, Ayako; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Nippon Kikai Gakkai Netsu Kogaku Konfarensu 2019 Koen Rombunshu (USB Flash Drive), 1 Pages, 2019/10

no abstracts in English

Journal Articles

Simultaneous measurement of dry patch behavior and surface temperature distribution for copper heat transfer surface with deposition layer in nucleate pool boiling

Uesawa, Shinichiro; Ono, Ayako; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Nippon Kikai Gakkai Netsu Kogaku Konfarensu 2018 Koen Rombunshu (USB Flash Drive), 6 Pages, 2018/10

no abstracts in English

Journal Articles

Observation of dry patch behavior on copper heat transfer surface and measurement of surface temperature distribution in nucleate pool boiling

Uesawa, Shinichiro; Ono, Ayako; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Dai-55-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 8 Pages, 2018/05

no abstracts in English

Journal Articles

Saturated pool nucleate boiling on heat transfer surface with deposited sea salts

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Journal of Nuclear Engineering and Radiation Science, 3(4), p.041002_1 - 041002_13, 2017/10

Journal Articles

Study on fundamental process of seawater pool nucleate boiling heat transfer

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Thermal Science and Engineering, 25(4), p.65 - 74, 2017/10

no abstracts in English

Journal Articles

Study on forced-convective boiling heat transfer of seawater with sea salt deposition

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Nagatake, Taku; Yoshida, Hiroyuki

Konsoryu, 31(2), p.162 - 170, 2017/06

no abstracts in English

Journal Articles

Study on fundamental process of seawater pool nucleate boiling heat transfer

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Dai-54-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu (CD-ROM), 8 Pages, 2017/05

no abstracts in English

Journal Articles

Study on pool nucleate boiling heat transfer of suspension liquid with deposits on heat transfer surface

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Thermal Science and Engineering, 25(2), p.17 - 26, 2017/04

no abstracts in English

Journal Articles

Study on spray cooling capability for spent fuel pool at coolant loss accident, 1; Research plan

Liu, W.; Nagatake, Taku; Shibata, Mitsuhiko; Koizumi, Yasuo; Yoshida, Hiroyuki; Nemoto, Yoshiyuki; Kaji, Yoshiyuki

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 4 Pages, 2016/11

The Fukushima Daiichi NPP accident asks that the accident management of the LOCA in the SFPs must be considered to avoid occurrences of severe accident in the SFPs. To prevent the failure of the spent fuel assemblies at the LOCA, transportable spray systems are expected to be put into use to discharge water into fuel assemblies to moderate the temperature increase. To apply the spray system as a countermeasure for the LOCA of the SFP, the capability of the spray cooling system must be evaluated to keep the spent fuel rods safety. JAEA has started the research project to investigate the spray cooling capability for the SFP. In this research project, we aim to construct a numerical simulation method for evaluating the capability of the spray cooling. To develop the method, the basic key phenomena that affect the cooling performance must be clarified and the validation data required for the code development. To clarify the basic key phenomena that affect the cooling performance, that is, the CCFL and the drop size effect on the CCFL, and to obtain the code validation data, we are planning to carry out 2 experiments with two test sections, the spray visualization experiment and the spray cooling experiment. The spray visualization test section aims to get CCFL data in air-water two-phase flow and to understand the two-phase flow behavior over the upper tie plate. The spray cooling test section aims to get the CCFL data in steam-water two-phase flow and to obtain the validation data. This paper focus on the outline of the research plan for the whole research project.

Journal Articles

Study on occurrence mechanism of critical heat flux condition of heat transfer surface with deposition

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Nippon Kikai Gakkai Netsu Kogaku Konfarensu 2016 Koen Rombunshu (USB Flash Drive), 2 Pages, 2016/10

no abstracts in English

Journal Articles

Visualization study on two-phase flow behavior at spray cooling for spent fuel pool

Nagatake, Taku; Liu, W.; Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki; Nemoto, Yoshiyuki; Kaji, Yoshiyuki

Konsoryu Shimpojiumu 2016 Koen Rombunshu (USB Flash Drive), 2 Pages, 2016/08

no abstracts in English

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo; Ohshima, Hiroyuki; Kawamura, Takumi*

Mechanical Engineering Journal (Internet), 3(3), p.15-00671_1 - 15-00671_9, 2016/06

Journal Articles

Pool nucleate boiling on heat transfer surface with deposited sea salts

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 15 Pages, 2016/06

Journal Articles

Study on pool nucleate boiling heat transfer of suspension liquid with deposits on heat transfer surface

Uesawa, Shinichiro; Koizumi, Yasuo; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Dai-53-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu (CD-ROM), 8 Pages, 2016/05

no abstracts in English

Journal Articles

Pool nucleate boiling for seawater containing minerals

Uesawa, Shinichiro; Koizumi, Yasuo; Yoshida, Hiroyuki

Proceedings of 9th International Conference on Multiphase Flow (ICMF 2016) (CD-ROM), 6 Pages, 2016/05

Journal Articles

Experiments of coolant accumulation in SG U tube and analytical model development

Yamaji, Tatsuya*; Koizumi, Yasuo; Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Onuki, Akira*; Kanamori, Daisuke*

Konsoryu Shimpojiumu 2015 Koen Rombunshu (USB Flash Drive), 2 Pages, 2015/08

Experiments of condensing counter-current two-phase flow in a vertical pipe were performed. This study was intended to examine water accumulation in the up-flow side of steam generator U-tubes of a PWR during the reflux cooling stage of a small break LOCA. It has been apprehended that the water accumulation may result in temporary core liquid level depression. The inner diameter and the length of a test flow channel used in the experiments were 18 mm and 4 m, respectively. The experiments were performed by using steam and water at 0.1 MPa. Two kinds of experiments were conducted; visualization experiments by using a transparent test section and quantitative water accumulation evaluation experiments by using a brass test section. Even if water on the inner surface of the test pipe could not flow downward at the lower portion of the test pipe, a part of water became to flow downward at the upper portion of the test pipe since steam velocity decreased because of condensation. Thus, two-phase mixture level was formed in the upper portion of the test pipe, which resulted in the water accumulation in the pipe. The model to predict the water accumulation was proposed. It predicted the water accumulation reasonably well.

Journal Articles

Study on flow boiling heat transfer in horizontal-rectangular-narrow-flat channels

Koizumi, Yasuo; Ohira, Koji*

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), 14 Pages, 2015/08

In this study, to examine the channel narrowing effect on the two-phase flow boiling heat transfer, single-phase flow and flow boiling heat transfer experiments were performed for a thin rectangular channel of the width W = 3 mm and the height $$delta$$ = 1.25 mm $$sim$$ 0.163 mm. When the hydraulic diameter became smaller than 1.06 mm, for the single-phase flow conditions, the heat transfer coefficient became smaller than that for a conventional size channel. In the flow boiling, churn flow appeared even at a low heat flux and a flow pattern was mainly the churn flow or/and the annular flow. The critical heat flux was higher than the value of Kutateladze correlation for the pool boiling. However, when the flow channel height became extremely narrow, measured critical heat flux became lower than the Kutateladze value. based on these results, the modification method to incorporate the channel narrowing effect into the heat transfer coefficient correlation was proposed.

Journal Articles

Study on heat transfer mechanism elucidation during pool nucleate boiling by measuring instantaneous surface temperature distribution with infrared radiation camera

Koizumi, Yasuo; Takahashi, Kazuki*; Uesawa, Shinichiro; Yoshida, Hiroyuki; Takase, Kazuyuki

Dai-52-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu (CD-ROM), P. 2, 2015/06

Pool nucleate boiling heat transfer experiments were performed for water at 0.101 MPa to examine the elementary process of the nucleate boiling. The copper printed circuit board of a 1.57 mm thick bakelite plate coated with a 0.035 mm thick copper membrane was used for a heat transfer surface. The size of the heat transfer surface was 10 mm $$times$$ 10 mm. direct current was supplied to it to heat it up. The bakelite plate of the backside of the copper layer was taken by 7 mm $$times$$ 10 mm. The instantaneous variation of the backside temperature of the heat transfer surface was measured with an infrared radiation camera. The time and the space resolution of the infrared cameras used in experiments were 120 Hz and 0.315 mm $$times$$ 0.315 mm, respectively. Surface temperatures just before the burn-out measured with 120 Hz suggest that the surface temperature was steadily low at a large part of the heat transfer surface. A small hot-dry area came out at the critical heat flux condition. Then, this small hot-dry area iterated to expand and shrink and gradually grew. Other area was still wetted and kept at low temperature. Eventually the small hot-dry area started to grow continuously and a whole part of the heat transfer surface became hot-dry to reach the physical burn-out. The heat transfer surface was divided into two large areas; the hot-dry area and the low-temperature wetted area until the physical burn-out. The local surface heat flux variation derived from measured surface temperature variation clearly illustrated that the boundary between the dried area and the wetted area moved back and forth and the dried arear gradually grew to reach physical bourn-out at the critical heat flux condition.

Journal Articles

Behavior of entrainment droplet formed by high velocity air jet flow in stagnant water

Akabane, Masaaki*; Horiki, Sachiyo*; Osakabe, Masahiro*; Koizumi, Yasuo; Uchibori, Akihiro; Ohno, Shuji; Ohshima, Hiroyuki

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

Behavior of liquid droplets in a high-velocity gaseous jet was experimentally investigated to provide validation data for the evaluation method of sodium-water reaction phenomenon. The visualization experiment on the entrained liquid droplets in the air jet submerged in a water pool was carried out. Filament-like wisps from the wavy gas-liquid interface were observed. The wisps were broken off and entrained into the air jet. The velocity of the entrained liquid droplets was estimated from an image processing. The axial velocity of the liquid droplets increased as the air inlet velocity increased. Acceleration behavior of the liquid droplets was also confirmed quantitatively.

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo*; Ohshima, Hiroyuki; Kawamura, Takumi*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

The authors are developing a high-precision CFD code with an interface tracking method to simulate the gas entrainment (GE) phenomena in sodium-cooled fast reactors (SFRs), which might be caused by a highly-intensified free surface vortex. The GE in SFRs is characterized by an elongated interfacial dent along the vortex core and the bubble pinch-off at the tip of the dent. To simulate this complicated phenomenon, our simulation code has physics-basis algorithms which model accurately the interfacial dynamic behavior, the pressure jump condition at an interface and the surface tension. Several verification problems have been already solved and the accuracy of each individual algorithm is confirmed. In this paper, a basic experiment of the GE is simulated to validate the developed code. The simulation result of the entrained flow rate shows comparable value to the experimental data, that is, our simulation code is considered applicable to the evaluation of the GE in SFRs.

190 (Records 1-20 displayed on this page)