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Kevin A. Francesconi - One of the best experts on this subject based on the ideXlab platform.
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Quantification of Arsenolipids in the Certified Reference Material NMIJ 7405‑a (Hijiki) using HPLC/Mass Spectrometry after Chemical
2016Co-Authors: Ronald A. Glabonjat, Georg Raber, Kenneth B. Jensen, Josef Ehgartner, Kevin A. FrancesconiAbstract:ABSTRACT: Arsenic-containing lipids (arsenolipids) are novel natural products recently shown to be widespread in marine animals and algae. Research interest in these arsenic compounds lies in their possible role in the membrane chemistry of organisms and, because they occur in many popular seafoods, their human metabolism and toxicology. Progress has been restricted, however, by the lack of standard arsenolipids and of a quantitative method for their analysis. We report that the certified reference material CRM 7405-a (Hijiki) is a rich source of arsenolipids, and we describe a method based on HPLC-ICPMS/ESMS to quantita-tively measure seven of the major arsenolipids present. Sample preparation involved extraction with DCM/methanol, a cleanup step with silica, and conversion of the (oxo)arsenolipids originally present to thio analogues by brief treatment with H2S. Compared to their oxo analogues, the thioarsenolipids showed much sharper peaks on reversed-phase HPLC, which facilitated their resolution and quantification. The compounds were determined by HPLC-ICPMS and HPLC-ESMS, which provided bot
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Quantification of Arsenolipids in the Certified Reference Material NMIJ 7405‑a (Hijiki) using HPLC/Mass Spectrometry after Chemical Derivatization
2015Co-Authors: Ronald A. Glabonjat, Georg Raber, Kenneth B. Jensen, Josef Ehgartner, Kevin A. FrancesconiAbstract:Arsenic-containing lipids (arsenolipids) are novel natural products recently shown to be widespread in marine animals and algae. Research interest in these arsenic compounds lies in their possible role in the membrane chemistry of organisms and, because they occur in many popular seafoods, their human metabolism and toxicology. Progress has been restricted, however, by the lack of standard arsenolipids and of a quantitative method for their analysis. We report that the certified reference material CRM 7405-a (Hijiki) is a rich source of arsenolipids, and we describe a method based on HPLC-ICPMS/ESMS to quantitatively measure seven of the major arsenolipids present. Sample preparation involved extraction with DCM/methanol, a cleanup step with silica, and conversion of the (oxo)arsenolipids originally present to thio analogues by brief treatment with H2S. Compared to their oxo analogues, the thioarsenolipids showed much sharper peaks on reversed-phase HPLC, which facilitated their resolution and quantification. The compounds were determined by HPLC-ICPMS and HPLC-ESMS, which provided both arsenic-selective detection and high resolution molecular mass detection of the arsenolipids. In this way, the concentrations of two arsenic-containing hydrocarbons and five arsenosugar phospholipids are reported in the CRM Hijiki. This material may serve as a convenient source of characterized arsenolipids to delineate the presence of these compounds in seafoods and to facilitate research in a new era of arsenic biochemistry
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quantification of arsenolipids in the certified reference material nmij 7405 a Hijiki using hplc mass spectrometry after chemical derivatization
Analytical Chemistry, 2014Co-Authors: Ronald A. Glabonjat, Georg Raber, Kenneth B. Jensen, Josef Ehgartner, Kevin A. FrancesconiAbstract:Arsenic-containing lipids (arsenolipids) are novel natural products recently shown to be widespread in marine animals and algae. Research interest in these arsenic compounds lies in their possible role in the membrane chemistry of organisms and, because they occur in many popular seafoods, their human metabolism and toxicology. Progress has been restricted, however, by the lack of standard arsenolipids and of a quantitative method for their analysis. We report that the certified reference material CRM 7405-a (Hijiki) is a rich source of arsenolipids, and we describe a method based on HPLC-ICPMS/ESMS to quantitatively measure seven of the major arsenolipids present. Sample preparation involved extraction with DCM/methanol, a cleanup step with silica, and conversion of the (oxo)arsenolipids originally present to thio analogues by brief treatment with H2S. Compared to their oxo analogues, the thioarsenolipids showed much sharper peaks on reversed-phase HPLC, which facilitated their resolution and quantificat...
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arsenosugar phospholipids and arsenic hydrocarbons in two species of brown macroalgae
Environmental Chemistry, 2012Co-Authors: Sara Garcia Salgado, Georg Raber, Reingard Raml, Christoph Magnes, Kevin A. FrancesconiAbstract:Environmental context Although organoarsenic compounds occur in marine organisms at high concentrations, the origin and role of these compounds is unknown. Arsenic-containing lipids (arsenolipids) are newly discovered compounds in fish. We identify a range of arsenolipids in algae and propose that algae are the origin of these unusual arsenic compounds in marine ecosystems. Abstract Fourteen arsenolipids, including 11 new compounds, were identified and quantified in two species of brown algae, Wakame (Undaria pinnatifida) and Hijiki (Hizikia fusiformis), by high resolution mass spectrometry, high performance liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry. Both algal species contained arsenosugar-phospholipids as the major type of arsenolipid, and arsenic-hydrocarbons were also significant components, particularly in Hijiki. The origin of the various arsenolipids, and the possible significance of their relative quantities, is briefly discussed.
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determination of water and lipid soluble arsenic compounds in the commercial edible seaweed Hijiki hizikia fusiforme
XXIII Reunión Nacional de Espectroscopía - VII Congreso Ibérico de Espectroscopía | XXIII Reunión Nacional de Espectroscopía - VII Congreso Ibérico de, 2012Co-Authors: Sara Garcia Salgado, Georg Raber, Reingard Raml, Christoph Magnes, Angeles Quijano M Nieto, Kevin A. FrancesconiAbstract:Se presentan los resultados obtenidos en los estudios de especiacion de arsenico realizados sobre el alga comestible Hijiki. Los analisis se realizaron a traves de metodos analiticos desarrollados en la UPM (Espana) y en la Universidad de Graz (Austria). La determinacion de especies hidrosolubles se realizo mediante HPLC-(UV)-HG-AFS, previa extraccion mediante MAE con agua desionizada. Por otro lado, la identificacion y cuantificacion de arsenolipidos se llevo a cabo mediante HPLC-ICPMS/ESMS, previa extraccion con cloroformo:metanol y purificacion mediante SPE.
Kenichi Hanaoka - One of the best experts on this subject based on the ideXlab platform.
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nitric acid based partial digestion method for selective determination of inorganic arsenic in Hijiki and application to soaked Hijiki
Journal of The Food Hygienic Society of Japan (shokuhin Eiseigaku Zasshi), 2008Co-Authors: Megumi Hamanonagaoka, Tsutomu Nishimura, Kenichi Hanaoka, Masakatsu Usui, Tamio MaitaniAbstract:Because there is a great difference between the toxicity of inorganic arsenic (As) and organic As in food, the JECFA has set a PTWI value for inorganic As (iAs) rather than for total As. The difference in As toxicity makes it necessary to extract iAs completely from food samples for toxicological analysis, but complete extraction of As from most foods including seaweed has not been achieved to date. We developed a partial-digestion method that uses nitric acid as a solvent in order to extract almost all arsenicals from the solid matrix of Hijiki (Hizikia fusiforme, a brown alga) samples. In this method, organic As species were not converted into iAs. HPLC/ICP-MS was then used to determine the concentration of iAs. Total As was measured by hydride generation-atomic absorption spectrometry. The adopted conditions for 0.1 g of ground fine powder sample were: 2 mL of 0.3 mol/L nitric acid; heating, 80 degrees C for 1 hr. Intra-laboratory validation of the method showed good precision and accuracy. The repeatability and intermediate precision for iAs were 1.5% and 1.5%, respectively. The LOD and LOQ for iAs were 0.14 and 0.46 mg/kg dry weight, respectively. Recovery studies performed by spiking 0.5 mg/kg dry weight as the LOQ level and by spiking 3 mg/kg dry weight as the iAs concentration of an un-spiked Hijiki sample showed good accuracy. The method was applied to Hijiki samples after a water soaking process and a water soaking and simmering process. The results suggested that the As concentration in Hijiki after both processes was lower than that before the treatments and that the water soaking and simmering process reduced the iAs concentration much more effectively than the water soaking process.
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temperature dependent extraction of trace elements in edible brown alga Hijiki hizikia fusiforme
Food Chemistry, 2007Co-Authors: Taddese Wondimu, Akio Ueno, Ikue Kanamaru, Yuki Yamaguchi, Robert I Mccrindle, Kenichi HanaokaAbstract:Trace elements were extracted from natural Hijiki by heating with water (25-95 °C) or commercial Hijiki by soaking, washing, and rinsing with water at room temperature. Eleven elements (As, B, Cd, Ce, Cu, Fe, Li, Sn, Tl, Y and Zn) were determined with ICP-MS in the acid-digested and diluted solutions of commercial/natural Hijiki or in the water extracts of natural Hijiki. Extractions were effective in removing metals in the range 55-65 °C. The traditional procedure of soaking and washing commercial Hijiki was inadequate to sufficiently lower trace elements. The iron concentration in commercial Hijiki was high, indicating a possible contribution from the iron cauldron used in producing commercial Hijiki. Results showed unsuitability of the commercial production process for reducing trace elements sufficiently. To lower trace elements, a procedure involving two steps was proposed for preparing consumable Hijiki. Hijiki may be recommended as a supplement for deficiencies of B, Fe, Cu and Zn.
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arsenic in the prepared edible brown alga Hijiki hizikia fusiforme
Applied Organometallic Chemistry, 2001Co-Authors: Kenichi Hanaoka, Toshikazu Kaise, Kenta Yosida, Mie Tamano, Takayoshi Kuroiwa, Shigeru MaedaAbstract:To reduce the arsenic content of the leaves and branches of an edible brown alga, Hijiki Hizikia fusiforme, the Japanese traditional washing and soaking process before cooking was shown to be effective: about 32 to 60% of the arsenic was removed from the alga at room temperature. Increasing the amount of water in which the Hijiki was soaked did not affect arsenic removal. On the other hand, arsenic content decreased linearly as the temperature used to wash and soak Hijiki increased from 0 to 60 °C. In the washed and soaked Hijiki, inorganic arsenic accounts for 90% of the total arsenic and dimethylated arsenic compounds 10%. Copyright © 2001 John Wiley & Sons, Ltd.
Masayuki Katayama - One of the best experts on this subject based on the ideXlab platform.
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do the tissue concentrations of accumulated arsenic calcium iron magnesium manganese potassium and zinc become uniform throughout the Hijiki plant body with growth
微量栄養素研究, 2014Co-Authors: Masayuki Katayama, Yohko Sugawakatayama, Kaori MurakamiAbstract:*** ) plant having genital organs was harvested on the Hime Coast, Kushimoto, Wakayama Prefecture, Japan, and the concentrations of accumulated arsenic, calcium, iron, magnesium, manganese, potassium, and zinc were determined. The fresh plants were washed thoroughly and cut at a length of 10 cm along the stalk from the bottom to the top of the plants. The twigs of the lower, middle and upper portions of the respective sections were separated to twig-stalks, twigs' large leaves and twig's small leaves. The genital organs of each section were also separated. The respective samples were weighed and stored under -40℃ until freeze-dried. The lyophilized samples were decomposed with conc HNO 3 and HClO4 on an electric furnace, and the respective el- ements were determined with an atomic absorption spectrophotometer. These plants, having genital organs con - tained rather constant levels of calcium, 11.7 ± 1.4 * (genital organs), ~ 12.2 ± 0.9* (leaves) mg Ca/g of dried tissues. They also contained rather constant levels of arsenic, 83.6 ± 12.07 * (stalks) ~ 110 ± 27.2 * (leaves) µg As/ g dry weight of tissues. Genital organs of some sections showed lesser arsenic accumulation than in most other sections, suggesting that accumulation started later in these sections. The concentrations of magnesium, manganese and zinc have not become uniform yet. However, the correlation coefficients between the accumulated magnesium and man - ganese were 0.93 to 0.69, and those between the accumulated manganese and zinc were 0.59 to 0.67. Thus, these elements seem to be accumulating more abundantly. Iron accumulation was, in average, 100.3 to 134.0 µg Fe/ g dry weight of tissues, but seems to be further continuing, as their accumulated concentrations had not become uni -
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accumulation of arsenic and calcium during the growth of Hijiki plants
微量栄養素研究, 2013Co-Authors: Masayuki Katayama, Motohiro Kasama, Yohko SugawakatayamaAbstract:Summary In an attempt to study the accumulation processes of nutritionally important as well as ecologically unavoidable minerals in growing Hijiki (Sargassum fusiforme (Harvey) Setchell ** ) plants, tissue concentrations of calcium and ar - senic were determined. Hijiki plants were harvested in several stages of their growth from November through April. Fresh plants were washed thoroughly and cut at a length of 10 cm along the stalk from the bottom to the top of the plants. The leaves and stalks were separated, weighed and stored at -40℃ until freeze-dried. Arsenic was determined by HPLC-ICP-MS analysis after extraction of the samples with a HNO 3 solution, and calcium was determined by atomic absorption spectrophotometry in a 1M HCl solution containing strontium chloride, after ashing the samples with a mixture of conc. H 2SO4-conc. HNO 3 on an electric furnace. The distribution of arsenic concentra - tions showed a correlation with those of calcium during growth of Hijiki plants, in contrast to the correlations be - tween arsenic and zinc, which correlated only in the earlier stages of growth, although these correlations were not
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accumulation of iron and magnesium in growing Hijiki sargassum fusiforme plants
微量栄養素研究, 2012Co-Authors: Masayuki Katayama, Motohiro Kasama, Yohko SugawakatayamaAbstract:Summary Hijiki (Sargassum fusiforme) plants were collected during their growth period from the end of November through April on the sea coast of Kushimoto, Wakayama, Japan. The samples were brought back to the laboratory under ice-cold condi- tions and washed thoroughly with artificial sea-water and distilled water successively. The plants were cut into pieces of a 10 cm length along the stalk, and separated into leaves and stalks. The samples were lyophilized, and decomposed in a mixture of conc H2SO4 and conc HNO3 (3 to 1, v/v) on an electric heater. Iron (Fe) and magnesium (Mg) in 1N HCl were determined with an atomic absorption spectrophotometer. Fe accumulated in the respective tissues at concentrations of 70 to 110μg/g dry weight of tissues at the beginning of growth and Mg, at concentrations of 7 to 9 mg/g dry weight of tissues. Fe accumulated at 20 to 300μg/g dry weight through the growing period until the beginning of April. Mg accumulated at 5 to 30 mg/g dry weight of tissues through the growing period. Mg accumulation seemed to be more than enough for its biochemically required concentrations in the tissues of Hijiki.
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accumulation of manganese and zinc in growing Hijiki sargassum fusiforme plants
微量栄養素研究, 2011Co-Authors: Masayuki Katayama, Yohko Sugawakatayama, Motohiro Kasama, Etsu KishidaAbstract:Summary Hijiki (Sargassum fusiforme) plants were collected during their growth period from the end of November through April at the sea coast of Kushimoto, Wakayama, Japan. The samples were brought back to the laboratory under ice-cold con- ditions and washed thoroughly with artificial sea-water and distilled water successively. The plants were cut into piec- es of a 10 cm length along the stalk, and separated into leaves and stalks. The samples were lyophilized, and decom- posed in a mixture of conc H2SO4 and conc HNO3 (3 to 1, v/v) on an electric heater. Manganese (Mn) and zinc (Zn) in 1N HCl were determined with an atomic absorption spectrophotometer. Mn and Zn accumulated in the respective tissues at concentrations of 10 to 50 µg/g dry weight of tissues at the begin- ning of growth, and their concentrations remained at similar levels until the beginning of April. These may, as discussed, suggest that the levels of Mn and Zn are their biochemically required concentrations in the tissues of Hijiki.
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effects of digestive enzymes on the retained arsenic in dried Hijiki sargassum fusiforme
微量栄養素研究, 2010Co-Authors: Yohko Sugawakatayama, Masayuki Katayama, Hiroko ImanishiAbstract:＊, Summary Water‑swollen samples of Hijiki Sargassum fusiforme were treated with two digestive enzymes pepsin from porcine stomach mucosa and pancreatin from hog pancreas at 37℃ for 3 6 15 and 24 hr. Two fractions of arsenic one dis‑ solved and the other retained in the Hijiki residues were determined by thermal neutron activation analysis. The concentration of the retained arsenic in the Hijiki residues was 27 µgAs/g dry residue weight after single treat‑ ment with pepsin 25 µgAs/g dry residue weight after single treatment with pancreatin and 24 µgAs/g dry residue weight after successive treatment with pepsin followed by pancreatin.
Shigeru Maeda - One of the best experts on this subject based on the ideXlab platform.
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arsenic in the prepared edible brown alga Hijiki hizikia fusiforme
Applied Organometallic Chemistry, 2001Co-Authors: Kenichi Hanaoka, Toshikazu Kaise, Kenta Yosida, Mie Tamano, Takayoshi Kuroiwa, Shigeru MaedaAbstract:To reduce the arsenic content of the leaves and branches of an edible brown alga, Hijiki Hizikia fusiforme, the Japanese traditional washing and soaking process before cooking was shown to be effective: about 32 to 60% of the arsenic was removed from the alga at room temperature. Increasing the amount of water in which the Hijiki was soaked did not affect arsenic removal. On the other hand, arsenic content decreased linearly as the temperature used to wash and soak Hijiki increased from 0 to 60 °C. In the washed and soaked Hijiki, inorganic arsenic accounts for 90% of the total arsenic and dimethylated arsenic compounds 10%. Copyright © 2001 John Wiley & Sons, Ltd.
Takashi Hibiki - One of the best experts on this subject based on the ideXlab platform.
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correction to effect of interfacial drag force model on code prediction for upward adiabatic two phase bubbly flow in vertical channels
Experimental and Computational Multiphase Flow, 2021Co-Authors: Takashi Hibiki, Tetsuhiro OzakiAbstract:The article “Effect of interfacial drag force model on code prediction for upward adiabatic two-phase bubbly flow in vertical channels” written by Takashi Hibiki and Tetsuhiro Ozaki, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 04 January 2020 without open access. After publication in Volume 2, Issue 4, page 212–224, the author(s) decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
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validation of interfacial area concentration model for simulating bubbly and cap slug flow behaviors in large diameter pipes using lstf atlas and horizontal pipe experiment data
Progress in Nuclear Energy, 2020Co-Authors: Jaeseok Heo, Seung Hyun Yoon, Kyung Doo Kim, Takashi HibikiAbstract:Abstract This study discusses Interfacial Area Concentration (IAC) models developed for bubbly and cap/slug flow regimes in a large diameter pipe incorporating recently developed small bubble fraction correlations in various flow conditions. The main focus of this study was the robust simulation of the behaviors of bubbly and cap/slug flows in large diameter pipes observed in Large Scale Test Facility (LSTF), Advanced Thermal-hydraulic test Loop for Accident Simulation (ATLAS), and horizontal flow test facility. Since the IAC was one of the key parameters to achieve this, an IAC model for large diameter pipes was first derived based on the existing Hibiki-Ishii IAC model for bubbly flow, and the Shen-Hibiki IAC model for cap bubbly-to-churn flow. The volume fraction of group-1 bubbles, i.e., small spherical bubbles, in the IAC model, which have been developed based on the assumption that the group-1 bubbles exponentially decay in the slug flow regime, was refined. As a result, a more physical model of the group-1 bubble number density that remains constant in the cap/slug flow regime was imposed for large diameter pipes. The validity of the IAC model for large diameter pipes in predicting the interfacial drag force between gas and liquid phases in large pipes of multiple test facilities was then examined. The validation of the proposed IAC model was conducted through simulations of 1) the loss of Residual Heat Removal (RHR) during the mid-loop operation of the LSTF, 2) the 6-inch Small Break Loss of Coolant Accident (SBLOCA) of the ATLAS, and 3) the two-phase flow behaviors under a wide range of fluid conditions in the horizontal pipe test facility. Improved results were obtained with the proposed model as it indicated that there was good agreement between the calculated results and the experimental data throughout the whole transient.
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bubble coalescence and breakup model evaluation and development for two phase bubbly flows
International Journal of Multiphase Flow, 2018Co-Authors: Xiuzhong Shen, Takashi HibikiAbstract:Abstract The performance of thermal-hydraulics analysis codes heavily depends on the reliable models developed for interfacial transfer terms in the two-fluid model. This requires the accurate modeling of the interfacial area concentration (IAC). The interfacial area transport equation (IATE) developed from the population balance equation is one of the promising ways to be able to dynamically describe the IAC evolutions in the two-phase flows. A lot of efforts have been made to develop the IATE and its bubble coalescence and breakup models in the past two decades. The one-group IATE with its bubble coalescence and breakup models serves as an important and promising model to predict the IAC behaviors in the bubbly flows now. This paper made an extensive survey on the recent theoretical and experimental researches on the IATE and collected the available 8 sets of bubble coalescence and breakup models and the latest experimental databases measured with the up-to-date measuring techniques. The 8 sets of bubble coalescence and breakup models are originally developed to model the bubble evolution in bubbly flows and the small bubble evolution in the flows beyond bubbly flow. The collected data covers the bubbly flows taken the vertical pipes with the diameter ranging from 0.0508 m to 0.200 m and the height-to-diameter ratio ranging from 4 to 113. To confirm the reliability of the 8 sets of bubble coalescence and breakup models, this paper systematically compared and evaluated them with the collected experimental data in the 1D one-group IATE numerical calculations. Although the bubble coalescence and breakup models of Sun et al. (2004, Modeling of bubble coalescence and disintegration in confined upward two-phase flow. Nucl. Eng. Des. 230, 3–26) and Hibiki and Ishii (2000, One-group interfacial area transport of bubbly flows in vertical round tubes. Int. J. Heat Mass Transfer 43, 2711–2726) were found to show the best and second-best predicting performance for the collected latest experimental databases of bubbly flows with data-number-averaging mean absolute relative errors of 33.5% and 61.7% respectively, their relative errors are not satisfactory. Hibiki and Ishii (2000, One-group interfacial area transport of bubbly flows in vertical round tubes. Int. J. Heat Mass Transfer 43, 2711–2726) model only consisting of the contributions of the bubble random collision coalescence and turbulent impact breakup mechanisms can reasonably predict the IAC experimental data in the bubbly flows with high-liquid flow-rate flow conditions and significantly overpredict the IAC experimental data in the bubbly flows with low-liquid flow-rate flow conditions. To further improve the performance of the 1D one-group IATE, this paper has developed a bubble coalescence and breakup model by greatly improving the model of Hibiki and Ishii (2000, One-group interfacial area transport of bubbly flows in vertical round tubes. Int. J. Heat Mass Transfer 43, 2711–2726) with the addition of the contribution of the wake entrainment bubble coalescence mechanism which prevails in low-liquid flow-rate bubbly flows and optimized the adjustable coefficients of the 3 major constitutive models with the collected latest experimental databases of bubbly flows. The data-number-averaging mean absolute relative error of the newly-proposed bubble coalescence and breakup model is accordingly improved to be 17.1% in the predictions of the collected latest experimental databases of bubbly flows.
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bubble breakup and coalescence models for bubbly flow simulation using interfacial area transport equation
International Journal of Heat and Mass Transfer, 2018Co-Authors: Takashi HibikiAbstract:Abstract This paper provides the state-of-the-art critical review on the modeled source and sink terms of the one-group interfacial area transport equation. The reviewed source and sink terms include models developed by Wu et al., Hibiki and Ishii, Hibiki et al., Yao and Morel, Park et al., Hibiki et al., Kataoka et al., Nguyen et al., Shen and Hibiki and Hazuku et al. The present critical review assesses major issues in modeling the one-group source and sink terms. Important conclusions are that the existing source and sink terms are not well-validated for developing and transient flows and the applicability of the source and sink terms to high pressure conditions such as prototypic nuclear reactor conditions has not been well-discussed. In view of these, coefficients of the source and sink terms in Hibiki and Ishii’s model have been modified for their application to prototypic nuclear reactor conditions. In addition, approximated area-averaged source and sink terms due to turbulent diffusion and lateral migration are derived by area-averaging local source and sink terms due to turbulent diffusion and lateral migration developed by Kataoka et al. The role of the area-averaged source and sink terms due to turbulent diffusion and lateral migration on the interfacial area transport should be tested in a future study. This paper also overviews important model validation challenges to be addressed in a future study. The challenging model validation should address the model performance for various test sections and flow conditions. They are (1) the effect of channel size (small (or micro/mini)-to-large channels) on the interfacial area transport, (2) the scalability of the interfacial area transport equation to prototypic nuclear reactor conditions, (3) the effect of covariance due to phase distribution on the interfacial area transport, (4) the effect of inlet conditions on the interfacial area transport, (5) the applicability of the interfacial area transport equation to transient and developing flow conditions, and (6) the applicability of the interfacial area transport equation to various flow channels including a rod bundle.
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one dimensional interfacial area transport for bubbly two phase flow in vertical 5 5 rod bundle
International Journal of Heat and Fluid Flow, 2018Co-Authors: Hang Liu, Takashi Hibiki, Liangming Pan, Wenxiong Zhou, Quanyao RenAbstract:Abstract For the modeling of the interfacial structure characteristics, an experiment of vertical adiabatic air-water flow has been conducted under an atmosphere pressure condition. The experimental facility is composed of 5 × 5 rods arranged on a square pitch in a square casing with 9.5 mm outside rod diameter and 12.6 mm pitch, simulating a prototypic rod bundle in nuclear reactors. The miniaturized four-sensor conductivity probe has been developed to allow for the experimental measurement in the small flow channel. Extensive data are acquired for one-dimensional flow parameters including axial development of void fraction, interfacial area concentration and gas velocity. The effect of a prototypic spacer grids with mixing vanes on the flow structure has been discussed at various flow conditions based on the experimental data. Two competing effects, “swirling effect” and “bubble breaker effect”, are identified. The effect vanishes out within a short distance from the space grid. A drift-flux correlation is developed for predicting void fraction of adiabatic bubbly two-phase flow in a vertical rod bundle. Existing interfacial area correlations are tested and Hibiki-Ishii correlation (2002b) is recommended as most accurate correlation to predict the interfacial area concentration. It is expected that the newly obtained data in the 5 × 5 rod bundle is useful for developing the interfacial area transport equation and benchmarking a computational code.