The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Ho-ming Yeh - One of the best experts on this subject based on the ideXlab platform.
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Recovery of deuterium from H–D gas mixture in thermal diffusion columns connected in series with Countercurrent-Flow transverse sampling streams
International Journal of Hydrogen Energy, 2016Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The equations for predicting the degrees of separation of H 2 , HD and D 2 from H–D gas mixture by thermal diffusion in Countercurrent-Flow concentric-tube Frazier schemes of single and multiple columns, have been derived. The equations for predicting the recovery of deuterium (D) in HD and D 2 were then obtained with the use of the atomic weight ratio. The degrees of separation, as well as separation factors, for deuterium recovery in the cryogenic-wall thermal diffusion devices were estimated, with the use of the experimental data obtained by Arita et al., 1998 and with the transport coefficients correlated in the previous work. Considerable improvement in deuterium recovery is achievable if a Frazier scheme with multiple columns is employed, instead of using the single-column device, either with the same column height, or with the same total sum of column heights, especially for the operation under larger volume Flow rate and/or higher operating pressure. Further, Countercurrent-Flow operation is better than concurrent-Flow operation in multi-column devices.
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The Improvement of Removal Rate in Countercurrent-Flow Frazier Scheme of Thermal Diffusion Columns with Optimal Plate Spacing
2013Co-Authors: Ho-ming YehAbstract:This work investigated the plate spacing effect on binary mixture separation removal rate in a Countercurrent-Flow Frazier scheme with N flat-plate thermal diffusion columns of the same size and with fixed total expense. The equations for estimating optimal plate spacing and the corresponding maximum removal rate are developed. Considerable improvement in performance is obtainable when thermal diffusion columns with optimal plate spacing are employed for operation. The fact that the Countercurrent-Flow operation is more effective than the cocurrent-Flow operation in a Frazier scheme, is also confirmed.
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Modified correction-factor analysis on membrane extraction in multipass Countercurrent-Flow external-recycle rectangular modules
Journal of the Taiwan Institute of Chemical Engineers, 2012Co-Authors: Ho-ming Yeh, Chang-chin YangAbstract:Abstract In the present study the modified correction-factor analysis is introduced to investigate the Performances in multipass Countercurrent-Flow recycled membrane extractors, in which the unknown solute outlet concentrations are neither in the estimating equation for mass-transfer rate nor in the modified correction-factor charts, and thus the calculation is easy and direct without using the try-and-error method, which should be employed in the conventional correction-factor analysis. Experimental results confirm the prediction values for the extraction of acetic acid from aqueous solution by methyl isobutyl ketone in the double-pass device.
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The optimal number of thermal diffusion columns for deuterium recovery from H–D gas mixture in the Countercurrent-Flow Frazier scheme with the total sum of column heights fixed
Progress in Nuclear Energy, 2012Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The effect of the column number on deuterium recovery from H–D gas mixture in the Countercurrent-Flow Frazier scheme of thermal diffusion columns with the total sum of column heights fixed, has been investigated. The equations for predicting the optimal number of columns and the corresponding maximum separation have been derived. Considerable improvement in deuterium recovery is obtainable if the multi-column device with the optimal number of columns is employed, instead of using the single-column device with the same total sum of column heights, especially for the cases of higher volume Flow-rate operation and larger total sum of column heights. Furthermore, Countercurrent-Flow operation is much better than forward-Flow operation.
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Further study on heavy water enrichment by thermal diffusion in the Countercurrent-Flow Frazier scheme
Journal of the Taiwan Institute of Chemical Engineers, 2011Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The separation theory for heavy water enrichment from water–isotope mixture in the Countercurrent-Flow Frazier scheme of thermal diffusion columns has been modified by the method of least squares. The results show that if the degree of separation is calculated from the modified separation equation, a serious error will be prevented, especially for employing the Frazier scheme with larger number of thermal diffusion columns.
Ching Chun Hsu - One of the best experts on this subject based on the ideXlab platform.
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Recovery of deuterium from H–D gas mixture in thermal diffusion columns connected in series with Countercurrent-Flow transverse sampling streams
International Journal of Hydrogen Energy, 2016Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The equations for predicting the degrees of separation of H 2 , HD and D 2 from H–D gas mixture by thermal diffusion in Countercurrent-Flow concentric-tube Frazier schemes of single and multiple columns, have been derived. The equations for predicting the recovery of deuterium (D) in HD and D 2 were then obtained with the use of the atomic weight ratio. The degrees of separation, as well as separation factors, for deuterium recovery in the cryogenic-wall thermal diffusion devices were estimated, with the use of the experimental data obtained by Arita et al., 1998 and with the transport coefficients correlated in the previous work. Considerable improvement in deuterium recovery is achievable if a Frazier scheme with multiple columns is employed, instead of using the single-column device, either with the same column height, or with the same total sum of column heights, especially for the operation under larger volume Flow rate and/or higher operating pressure. Further, Countercurrent-Flow operation is better than concurrent-Flow operation in multi-column devices.
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The optimal number of thermal diffusion columns for deuterium recovery from H–D gas mixture in the Countercurrent-Flow Frazier scheme with the total sum of column heights fixed
Progress in Nuclear Energy, 2012Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The effect of the column number on deuterium recovery from H–D gas mixture in the Countercurrent-Flow Frazier scheme of thermal diffusion columns with the total sum of column heights fixed, has been investigated. The equations for predicting the optimal number of columns and the corresponding maximum separation have been derived. Considerable improvement in deuterium recovery is obtainable if the multi-column device with the optimal number of columns is employed, instead of using the single-column device with the same total sum of column heights, especially for the cases of higher volume Flow-rate operation and larger total sum of column heights. Furthermore, Countercurrent-Flow operation is much better than forward-Flow operation.
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Further study on heavy water enrichment by thermal diffusion in the Countercurrent-Flow Frazier scheme
Journal of the Taiwan Institute of Chemical Engineers, 2011Co-Authors: Ho-ming Yeh, Ching Chun HsuAbstract:Abstract The separation theory for heavy water enrichment from water–isotope mixture in the Countercurrent-Flow Frazier scheme of thermal diffusion columns has been modified by the method of least squares. The results show that if the degree of separation is calculated from the modified separation equation, a serious error will be prevented, especially for employing the Frazier scheme with larger number of thermal diffusion columns.
Akio Tomiyama - One of the best experts on this subject based on the ideXlab platform.
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Countercurrent Flow limitation in a pressurizer surge line
Nuclear Engineering and Design, 2018Co-Authors: Yasunori Yamamoto, Michio Murase, Akio TomiyamaAbstract:Abstract In order to clarify the characteristics of Countercurrent Flow limitation (CCFL) in a pressurizer surge line, CCFL in a vertical pipe with a large diameter was evaluated using previous experimental data and a one-region model with an existing correlation of interfacial shear stress. The CCFL is defined by the relationship between the gas and liquid volumetric fluxes under a quasi-steady state after onset of flooding. A correlation for CCFL at the sharp-edged upper end of vertical pipes was constructed and it was compared to CCFL in the slightly inclined pipe. The comparison indicated that the liquid volumetric flux at the sharp-edged upper end was lower than that in a slightly inclined pipe when they have a large diameter such for an actual-scale pressurizer surge line. However, it was found that the liquid volumetric flux in integral experiments (including a slightly inclined pipe, a vertical elbow, and a vertical pipe) was lower than that in slightly inclined pipes and vertical pipes. Considering system characteristics from experimental data for the pressurizer surge line, it was concluded that the Kutateladze parameter should be applied with the slope of m = 0.94 and the constant of CK = 1.24 ± 0.1 for the Wallis type CCFL correlation.
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Prediction of Countercurrent Flow Limitation and Its Uncertainty in Horizontal and Slightly Inclined Pipes
Nuclear Technology, 2017Co-Authors: Michio Murase, Yoichi Utanohara, Takayoshi Kusunoki, Yasunori Yamamoto, Dirk Lucas, Akio TomiyamaAbstract:We proposed prediction methods for Countercurrent Flow limitation (CCFL) in horizontal and slightly inclined pipes with one-dimensional (1-D) computations and uncertainty of computed CCFL. In this ...
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Countercurrent Flow Limitation in Slightly Inclined Pipes With Elbows
Journal of Nuclear Engineering and Radiation Science, 2015Co-Authors: Michio Murase, Takayoshi Kusunoki, Dirk Lucas, Ikuo Kinoshita, Akio TomiyamaAbstract:One-dimensional (1D) sensitivity computations were carried out for air–water Countercurrent Flows in a 1/15-scale model of the hot leg and a 1/10-scale model of the pressurizer surge line in a pressurized water reactor (PWR) to generalize the prediction method for Countercurrent Flow limitation (CCFL) characteristics in slightly inclined pipes with elbows. In the 1D model, the wall friction coefficient fwG of single-phase gas Flows was used. The interfacial drag coefficient of fi=0.03, an appropriate adjustment factor of NwL=6 for the wall friction coefficient fwL of single-phase liquid Flows (NwG=1 for fwG of single-phase gas Flows), and an appropriate adjustment factor of Nde=6 for the pressure loss coefficient ζe of elbows in single-phase Flows were determined to give good agreement between the computed and measured CCFL characteristics. The adjusted factors were used to compute and then discuss effects of the inclination angle and diameter on CCFL characteristics.
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Correlation for Countercurrent Flow limitation in a PWR hot leg
Journal of Nuclear Science and Technology, 2012Co-Authors: Michio Murase, Yoichi Utanohara, Dirk Lucas, Akio Tomiyama, Ikuo Kinoshita, Chihiro YanagiAbstract:Numerical simulations were done to evaluate Countercurrent Flow limitation (CCFL) characteristics in a pressurized water reactor (PWR) hot leg with the diameter of 750 mm by using a volume of fluid (VOF) method implemented in the CFD software, FLUENT6.3.26. The calculated CCFL characteristics agreed well with known values including the UPTF data at 1.5 MPa. Sensitivity analyses for system pressures up to 8 MPa showed that the calculated CCFL characteristics in the Wallis diagram were slightly mitigated from 0.1 MPa to 1.5 MPa with increasing system pressure, but they did not change from 1.5 MPa to 8MPa. Using the CCFLs calculated in this study and values measured under air–water and steam–water conditions, a CCFL correlation and its uncertainty were derived.
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Numerical Simulation of Size Effects on Countercurrent Flow Limitation in PWR Hot Leg Models
Science and Technology of Nuclear Installations, 2012Co-Authors: Ikuo Kinoshita, Michio Murase, Akio TomiyamaAbstract:We have previously done numerical simulations using the two-fluid model implemented in the CFD software FLUENT6.3.26 to investigate effects of shape of a Flow channel and its size on CCFL (Countercurrent Flow limitation) characteristics in PWR hot leg models. We confirmed that CCFL characteristics in the hot leg could be well correlated with the Wallis parameters in the diameter range of . In the present study, we did numerical simulations using the two-fluid model for the air-water tests with ?m to determine why CCFL characteristics for ?m were severer compared with those in the range, . The predicted CCFL characteristics agreed with the data for ?m and indicated that the CCFL difference between ?m and m was caused by the size effect and not by other factors.
Michio Murase - One of the best experts on this subject based on the ideXlab platform.
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Countercurrent Flow limitation in a pressurizer surge line
Nuclear Engineering and Design, 2018Co-Authors: Yasunori Yamamoto, Michio Murase, Akio TomiyamaAbstract:Abstract In order to clarify the characteristics of Countercurrent Flow limitation (CCFL) in a pressurizer surge line, CCFL in a vertical pipe with a large diameter was evaluated using previous experimental data and a one-region model with an existing correlation of interfacial shear stress. The CCFL is defined by the relationship between the gas and liquid volumetric fluxes under a quasi-steady state after onset of flooding. A correlation for CCFL at the sharp-edged upper end of vertical pipes was constructed and it was compared to CCFL in the slightly inclined pipe. The comparison indicated that the liquid volumetric flux at the sharp-edged upper end was lower than that in a slightly inclined pipe when they have a large diameter such for an actual-scale pressurizer surge line. However, it was found that the liquid volumetric flux in integral experiments (including a slightly inclined pipe, a vertical elbow, and a vertical pipe) was lower than that in slightly inclined pipes and vertical pipes. Considering system characteristics from experimental data for the pressurizer surge line, it was concluded that the Kutateladze parameter should be applied with the slope of m = 0.94 and the constant of CK = 1.24 ± 0.1 for the Wallis type CCFL correlation.
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Prediction of Countercurrent Flow Limitation and Its Uncertainty in Horizontal and Slightly Inclined Pipes
Nuclear Technology, 2017Co-Authors: Michio Murase, Yoichi Utanohara, Takayoshi Kusunoki, Yasunori Yamamoto, Dirk Lucas, Akio TomiyamaAbstract:We proposed prediction methods for Countercurrent Flow limitation (CCFL) in horizontal and slightly inclined pipes with one-dimensional (1-D) computations and uncertainty of computed CCFL. In this ...
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Countercurrent Flow Limitation in Slightly Inclined Pipes With Elbows
Journal of Nuclear Engineering and Radiation Science, 2015Co-Authors: Michio Murase, Takayoshi Kusunoki, Dirk Lucas, Ikuo Kinoshita, Akio TomiyamaAbstract:One-dimensional (1D) sensitivity computations were carried out for air–water Countercurrent Flows in a 1/15-scale model of the hot leg and a 1/10-scale model of the pressurizer surge line in a pressurized water reactor (PWR) to generalize the prediction method for Countercurrent Flow limitation (CCFL) characteristics in slightly inclined pipes with elbows. In the 1D model, the wall friction coefficient fwG of single-phase gas Flows was used. The interfacial drag coefficient of fi=0.03, an appropriate adjustment factor of NwL=6 for the wall friction coefficient fwL of single-phase liquid Flows (NwG=1 for fwG of single-phase gas Flows), and an appropriate adjustment factor of Nde=6 for the pressure loss coefficient ζe of elbows in single-phase Flows were determined to give good agreement between the computed and measured CCFL characteristics. The adjusted factors were used to compute and then discuss effects of the inclination angle and diameter on CCFL characteristics.
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Effects of Shape and Size on Countercurrent Flow Limitation in Flow Channels Simulating a PWR Hot Leg
Nuclear Technology, 2014Co-Authors: Ikuo Kinoshita, Michio Murase, Yoichi Utanohara, Dirk Lucas, Christophe Vallée, And Akio TomiyamaAbstract:A numerical study is presented to examine the effects on Countercurrent Flow limitation (CCFL) of the shape and size of hot leg models with a rectangular cross section. The CCFL was described in te...
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Correlation for Countercurrent Flow limitation in a PWR hot leg
Journal of Nuclear Science and Technology, 2012Co-Authors: Michio Murase, Yoichi Utanohara, Dirk Lucas, Akio Tomiyama, Ikuo Kinoshita, Chihiro YanagiAbstract:Numerical simulations were done to evaluate Countercurrent Flow limitation (CCFL) characteristics in a pressurized water reactor (PWR) hot leg with the diameter of 750 mm by using a volume of fluid (VOF) method implemented in the CFD software, FLUENT6.3.26. The calculated CCFL characteristics agreed well with known values including the UPTF data at 1.5 MPa. Sensitivity analyses for system pressures up to 8 MPa showed that the calculated CCFL characteristics in the Wallis diagram were slightly mitigated from 0.1 MPa to 1.5 MPa with increasing system pressure, but they did not change from 1.5 MPa to 8MPa. Using the CCFLs calculated in this study and values measured under air–water and steam–water conditions, a CCFL correlation and its uncertainty were derived.
Somchai Wongwises - One of the best experts on this subject based on the ideXlab platform.
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Effect of inclination angles and upper end conditions on the Countercurrent Flow limitation in straight circular pipes
International Communications in Heat and Mass Transfer, 1998Co-Authors: Somchai WongwisesAbstract:Abstract In the present study, the experimental data of the Countercurrent Flow limitation (CCFL) for air and water in inclined pipes are investigated. Water is introduced at the top of the test section while air is injected at the bottom as Countercurrent Flow. The water Flow rate is fixed while the air Flow rate is slowly increased, until the CCFL is reached. Data from each experiment consists of the Flow rates of air and water. The curves of CCFL are built and shown as a function of the dimensionless superficial velocity. The influence of the inclination angles of the pipes and upper end conditions on CCFL are also discussed.
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Experimental investigation of two-phase Countercurrent Flow limitation in a bend between horizontal and inclined pipes
Experimental Thermal and Fluid Science, 1994Co-Authors: Somchai WongwisesAbstract:Abstract The Countercurrent Flow limitation (CCFL) or onset of flooding determines the maximum rate at which one phase can Flow Countercurrently to another phase. In the present study, the experimental data of the Countercurrent Flow limitation for air and water in a bend between a horizontal pipe and a pipe inclined to the horizontal are investigated. Water is introduced into the upper leg and Flows downward while the air injected into the horizontal leg Flows Countercurrently. The Flow patterns are visualized. The different mechanisms that lead to flooding and that are dependent on the water Flow rate are observed. For low and intermediate water Flow rates, the onset of flooding appears simultaneously with the slugging of unstable waves that are formed at the crest of the hydraulic jump. At low water Flow rates, slugging appears close to the bend; at higher water Flow rates, it appears far away from the bend in the horizontal section. For high water Flow rates, no hydraulic jump is observed, and flooding occurs as a result of slug formation at the water Flow outlet close to the end of the horizontal pipe. The influence of the inclination angle of the bends, the water inlet conditions, and the length of the horizontal pipes is of significance for the onset of flooding.
