The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Akio Tomiyama - One of the best experts on this subject based on the ideXlab platform.
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effects of swirler shape on swirling annular flow in a gas liquid Separator
Nuclear Engineering and Design, 2012Co-Authors: Toshiki Matsubayashi, Kenichi Katono, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract A downscaled model of a Steam Separator is used to experimentally examine the effects of swirler shape on swirling annular flow. Several swirlers having different vane angles, different hub diameters, and different number of vanes are installed in the Separator. Flow patterns, the ratio of the separated liquid flow rate to the total liquid flow rate, liquid film thickness, and pressure drop are measured. An improved swirler, which has a small hub diameter, the reduced number of vanes and modified vane shape, is also designed and its performance is examined. As a result, the following conclusions are obtained. (1) The reduction of the hub diameter and the number of vanes do not lower the Separator performance. (2) The decrease in vane angle deteriorates the separation performance. This is due to the decrease in the centrifugal force, i.e., the decrease in the amount of droplet deposition. (3) The improved swirler effectively reduces the pressure drop while keeping high Separator performance.
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Effects of swirler shape on swirling annular flow in a gas–liquid Separator
Nuclear Engineering and Design, 2012Co-Authors: Toshiki Matsubayashi, Kenichi Katono, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract A downscaled model of a Steam Separator is used to experimentally examine the effects of swirler shape on swirling annular flow. Several swirlers having different vane angles, different hub diameters, and different number of vanes are installed in the Separator. Flow patterns, the ratio of the separated liquid flow rate to the total liquid flow rate, liquid film thickness, and pressure drop are measured. An improved swirler, which has a small hub diameter, the reduced number of vanes and modified vane shape, is also designed and its performance is examined. As a result, the following conclusions are obtained. (1) The reduction of the hub diameter and the number of vanes do not lower the Separator performance. (2) The decrease in vane angle deteriorates the separation performance. This is due to the decrease in the centrifugal force, i.e., the decrease in the amount of droplet deposition. (3) The improved swirler effectively reduces the pressure drop while keeping high Separator performance.
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swirling annular flow in a Steam Separator
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2009Co-Authors: Hironobu Kataoka, Yusuke Shinkai, Shigeo Hosokawa, Akio TomiyamaAbstract:Effects of pick-off ring configuration on the Separator performance of a downscaled model of a Steam Separator for a boiling water nuclear reactor are examined using various types of pick-off rings. The experiments are conducted using air and water. Pressure drops in a barrel and a diffuser and diameters and velocities of droplets at the exit of the barrel are measured using differential pressure transducers and particle Doppler anemometry, respectively. The Separator performance does not depend on the shape of the pick-off ring but strongly depends on the width of the gap between the pick-off ring and the barrel wall. The pressure drop in the barrel is well evaluated using the interfacial friction factor for unstable film flows. Carry-under can be estimated using a droplet velocity distribution at the exit of the Separator.
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pressure drop in two phase swirling flow in a Steam Separator
Journal of Power and Energy Systems, 2009Co-Authors: Hironobu Kataoka, Yusuke Shinkai, Akio TomiyamaAbstract:Pressure drop and liquid film thickness in air-water swirling flows in a one-fifth scale model of the Steam Separator are measured for a wide range of gas and liquid volume fluxes. Numerical simulations based on one-dimensional single-fluid and two-fluid models are also carried out to examine the feasibility of predicting the pressure drop and film thickness in swirling flows. The pressure drop in a single-phase swirling flow is about five times as large as that in a non-swirling flow due to the increase in the frictional pressure drop. The pressure gradient and liquid film thickness in a two-phase swirling annular flow at the inlet of the pick-off-ring of the Separator are well evaluated by using a standard one-dimensional two-fluid model, provided that the interfacial and wall frictions in an ordinary two-phase annular flow are multiplied by appropriate constant values.
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effects of swirler shape on two phase swirling flow in a Steam Separator
Journal of Power and Energy Systems, 2009Co-Authors: Hironobu Kataoka, Yusuke Shinkai, Akio TomiyamaAbstract:Experiments on two-phase swirling flow in a Separator are carried out using several swirlers having different vane angles, different hub diameters and different number of vanes to seek a way for improving Steam Separators of uprated boiling water reactors. Ratios of the separated liquid flow rate to the total liquid flow rate, flow patterns, liquid film thicknesses and pressure drops are measured to examine the effects of swirler shape on air-water two-phase swirling annular flows in a one-fifth scale model of the Separator. As a result, the following conclusions are obtained for the tested swirlers: (1) swirler shape scarcely affects the pressure drop in the barrel of the Separator, (2) decreasing the vane angle is an effective way for reducing the pressure drop in the diffuser of the Separator, and (3) the film thickness at the inlet of the pick-off-ring of the Separator is not sensitive to swirler shape, which explains the reason why the Separator performance does not depend on swirler shape.
Yasuhiko Hirao - One of the best experts on this subject based on the ideXlab platform.
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Development of ATR Type Steam Separator Performance Analysis Code and Its Validation, (I)
Journal of Nuclear Science and Technology, 2012Co-Authors: Hiroyasu Mochizuki, Yasuhiko HiraoAbstract:The purpose of the study is to develop a method for predicting Steam carryunder which is one of the important characteristics of a Steam Separator. Bubbles returning to the liquid surface and trapped by the re-circulating flow are calculated by tracking the behavior of bubbles moving in liquid bulk where velocity and temperature distributions have been calculated beforehand in conjunction with the Monte-Carlo method. Regarding the statistics of bubbles, a survey of references and visual tests have been conducted. To validate this method, several tests to measure bubble behavior under air/water conditions at atmospheric pressure and high temperature and pressure ranging 3~7 MPa have been conducted with a full-scale Steam Separator. As a result, the developed method predicted with good precision the carryunder ratio obtained by the full-scale tests under the condition that carried-under void fraction was less than 20%, but underestimated carryunder ratio in the ATR “Fugen” reactor in which Steam drum water ...
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Development of Steam Separator Performance Analysis Code and Its Validation, (III)
Journal of Nuclear Science and Technology, 2012Co-Authors: Hiroyasu Mochizuki, Yasuhiko HiraoAbstract:The purpose of the present study is to develop computer program models in the Separator to analyze the behavior of droplets (carryover) which are ejected from the Separator on the basis of physical understanding of phenomena. Firstly, the behavior of Steam, liquid film, liquid droplets, and void in the Separator are calculated using basic conservation equations coupled with empirical correlations derived from the mock-up test. The behavior of droplets, droplets ejected from the Separator are analyzed by the following method. Steam velocity outside the Separator was calculated with the versatile 3-dimensional flow analysis code in advance, and the trajectory of each liquid droplet was calculated with the Monte Carlo method. Wetness fraction around the rated condition of the ATR-type Separator was calculated with the developed computer program, and compared with the measured data outside the Separator. Good agreement was obtained between calculated and measured results.
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Development of Steam Separator Performance Analysis Code and Its Validation, (II) Carryover Experiments
Journal of Nuclear Science and Technology, 1993Co-Authors: Hiroyasu Mochizuki, Yasuhiko HiraoAbstract:Abstract The purpose of the study is to collect data in order to make models that are applicable to calculate carryover droplets that are generated in and flow out of a Steam Separator. Various effective tests relevant to separation mechanisms in the Separator have been conducted with a full-scale Steam Separator under atmospheric pressure. Separation behaviors for the top of the riser of the Separator and for corrugated-Separator were clarified and correlated by the experiment. Distinct patterns about the separation at the corrugated-Separator, the separation of discharged droplets by gravity, and the separation of droplets by a screen dryer that is used to dry up the Steam were also measured with the facility using a full-scale Separator in a vessel simulating the flow area of ATR under the high-pressure and high-temperature condition for various water levels. Each separation data were correlated under the condition of maximum Steam and liquid flow rates of 7 and 30.5 kg/s, respectively. Liquid droplets...
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Development of ATR Type Steam Separator Performance Analysis Code and Its Validation, (I): Carryunder Characteristics
Journal of Nuclear Science and Technology, 1991Co-Authors: Hiroyasu Mochizuki, Yasuhiko HiraoAbstract:The purpose of the study is to develop a method for predicting Steam carryunder which is one of the important characteristics of a Steam Separator. Bubbles returning to the liquid surface and trapped by the re-circulating flow are calculated by tracking the behavior of bubbles moving in liquid bulk where velocity and temperature distributions have been calculated beforehand in conjunction with the Monte-Carlo method. Regarding the statistics of bubbles, a survey of references and visual tests have been conducted. To validate this method, several tests to measure bubble behavior under air/water conditions at atmospheric pressure and high temperature and pressure ranging 3~7 MPa have been conducted with a full-scale Steam Separator. As a result, the developed method predicted with good precision the carryunder ratio obtained by the full-scale tests under the condition that carried-under void fraction was less than 20%, but underestimated carryunder ratio in the ATR “Fugen” reactor in which Steam drum water ...
Kenichi Katono - One of the best experts on this subject based on the ideXlab platform.
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Air–water downscaled experiments and three-dimensional two-phase flow simulations of improved Steam Separator for boiling water reactor
Nuclear Engineering and Design, 2014Co-Authors: Kenichi Katono, Naoyuki Ishida, Takashi Sumikawa, Kenichi YasudaAbstract:Abstract Reducing the pressure losses in Steam-Separator systems in boiling water reactor (BWR) plants is useful for reducing the required pump head and enhancing the design margins to ensure core stability. We need to reduce the pressure losses while maintaining the gas–liquid separation performance. In this study, we improve a Steam Separator with air–water downscaled experiments and two-phase flow simulations. First, we confirm the effectiveness for the Separator performance prediction by adjusting the quality and the two-phase centrifugal force between the air–water downscaled experiments and the Steam-water mockup tests, and we design the improved Steam Separator, which moves the swirl-vane section from diffuser section to the first-barrel section. From the air–water downscaled experiments, the improved Separator can decrease pressure loss in the swirler more than 50% around the BWR normal operating conditions compared to the conventional Separator, and the carryover of the improved Separator is almost the same level as the conventional Separator. Next, we evaluate the improved Steam Separator performance under the BWR operating conditions by means of a two-phase flow simulation, and we have the prospects of the improved Separator for reducing the total Separator pressure losses by about 30% compared to the conventional Separator, while maintaining carryover characteristics.
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air water downscaled experiments and three dimensional two phase flow simulations of improved Steam Separator for boiling water reactor
Nuclear Engineering and Design, 2014Co-Authors: Kenichi Katono, Naoyuki Ishida, Takashi Sumikawa, Kenichi YasudaAbstract:Abstract Reducing the pressure losses in Steam-Separator systems in boiling water reactor (BWR) plants is useful for reducing the required pump head and enhancing the design margins to ensure core stability. We need to reduce the pressure losses while maintaining the gas–liquid separation performance. In this study, we improve a Steam Separator with air–water downscaled experiments and two-phase flow simulations. First, we confirm the effectiveness for the Separator performance prediction by adjusting the quality and the two-phase centrifugal force between the air–water downscaled experiments and the Steam-water mockup tests, and we design the improved Steam Separator, which moves the swirl-vane section from diffuser section to the first-barrel section. From the air–water downscaled experiments, the improved Separator can decrease pressure loss in the swirler more than 50% around the BWR normal operating conditions compared to the conventional Separator, and the carryover of the improved Separator is almost the same level as the conventional Separator. Next, we evaluate the improved Steam Separator performance under the BWR operating conditions by means of a two-phase flow simulation, and we have the prospects of the improved Separator for reducing the total Separator pressure losses by about 30% compared to the conventional Separator, while maintaining carryover characteristics.
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effects of swirler shape on swirling annular flow in a gas liquid Separator
Nuclear Engineering and Design, 2012Co-Authors: Toshiki Matsubayashi, Kenichi Katono, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract A downscaled model of a Steam Separator is used to experimentally examine the effects of swirler shape on swirling annular flow. Several swirlers having different vane angles, different hub diameters, and different number of vanes are installed in the Separator. Flow patterns, the ratio of the separated liquid flow rate to the total liquid flow rate, liquid film thickness, and pressure drop are measured. An improved swirler, which has a small hub diameter, the reduced number of vanes and modified vane shape, is also designed and its performance is examined. As a result, the following conclusions are obtained. (1) The reduction of the hub diameter and the number of vanes do not lower the Separator performance. (2) The decrease in vane angle deteriorates the separation performance. This is due to the decrease in the centrifugal force, i.e., the decrease in the amount of droplet deposition. (3) The improved swirler effectively reduces the pressure drop while keeping high Separator performance.
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Effects of swirler shape on swirling annular flow in a gas–liquid Separator
Nuclear Engineering and Design, 2012Co-Authors: Toshiki Matsubayashi, Kenichi Katono, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract A downscaled model of a Steam Separator is used to experimentally examine the effects of swirler shape on swirling annular flow. Several swirlers having different vane angles, different hub diameters, and different number of vanes are installed in the Separator. Flow patterns, the ratio of the separated liquid flow rate to the total liquid flow rate, liquid film thickness, and pressure drop are measured. An improved swirler, which has a small hub diameter, the reduced number of vanes and modified vane shape, is also designed and its performance is examined. As a result, the following conclusions are obtained. (1) The reduction of the hub diameter and the number of vanes do not lower the Separator performance. (2) The decrease in vane angle deteriorates the separation performance. This is due to the decrease in the centrifugal force, i.e., the decrease in the amount of droplet deposition. (3) The improved swirler effectively reduces the pressure drop while keeping high Separator performance.
Kenichi Yasuda - One of the best experts on this subject based on the ideXlab platform.
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Air–water downscaled experiments and three-dimensional two-phase flow simulations of improved Steam Separator for boiling water reactor
Nuclear Engineering and Design, 2014Co-Authors: Kenichi Katono, Naoyuki Ishida, Takashi Sumikawa, Kenichi YasudaAbstract:Abstract Reducing the pressure losses in Steam-Separator systems in boiling water reactor (BWR) plants is useful for reducing the required pump head and enhancing the design margins to ensure core stability. We need to reduce the pressure losses while maintaining the gas–liquid separation performance. In this study, we improve a Steam Separator with air–water downscaled experiments and two-phase flow simulations. First, we confirm the effectiveness for the Separator performance prediction by adjusting the quality and the two-phase centrifugal force between the air–water downscaled experiments and the Steam-water mockup tests, and we design the improved Steam Separator, which moves the swirl-vane section from diffuser section to the first-barrel section. From the air–water downscaled experiments, the improved Separator can decrease pressure loss in the swirler more than 50% around the BWR normal operating conditions compared to the conventional Separator, and the carryover of the improved Separator is almost the same level as the conventional Separator. Next, we evaluate the improved Steam Separator performance under the BWR operating conditions by means of a two-phase flow simulation, and we have the prospects of the improved Separator for reducing the total Separator pressure losses by about 30% compared to the conventional Separator, while maintaining carryover characteristics.
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air water downscaled experiments and three dimensional two phase flow simulations of improved Steam Separator for boiling water reactor
Nuclear Engineering and Design, 2014Co-Authors: Kenichi Katono, Naoyuki Ishida, Takashi Sumikawa, Kenichi YasudaAbstract:Abstract Reducing the pressure losses in Steam-Separator systems in boiling water reactor (BWR) plants is useful for reducing the required pump head and enhancing the design margins to ensure core stability. We need to reduce the pressure losses while maintaining the gas–liquid separation performance. In this study, we improve a Steam Separator with air–water downscaled experiments and two-phase flow simulations. First, we confirm the effectiveness for the Separator performance prediction by adjusting the quality and the two-phase centrifugal force between the air–water downscaled experiments and the Steam-water mockup tests, and we design the improved Steam Separator, which moves the swirl-vane section from diffuser section to the first-barrel section. From the air–water downscaled experiments, the improved Separator can decrease pressure loss in the swirler more than 50% around the BWR normal operating conditions compared to the conventional Separator, and the carryover of the improved Separator is almost the same level as the conventional Separator. Next, we evaluate the improved Steam Separator performance under the BWR operating conditions by means of a two-phase flow simulation, and we have the prospects of the improved Separator for reducing the total Separator pressure losses by about 30% compared to the conventional Separator, while maintaining carryover characteristics.
Zeljko Djurovic - One of the best experts on this subject based on the ideXlab platform.
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sensor fault detection and isolation in a thermal power plant Steam Separator
Control Engineering Practice, 2013Co-Authors: Nasar Aldian Ambark Shashoa, Aleksandra Marjanovic, Goran Kvaščev, Zeljko DjurovicAbstract:Abstract A fault detection and isolation approach, specially designed for Steam Separators in thermal power plants, is presented in the paper. The first step of the proposed algorithm is to identify the process. Because of the presence of sporadic high-intensity measurement noise (outliers), the paper proposes a robust version of recursive identification. Starting from the parameter vector of the identified model, the second step of the proposed procedure has the form of a data-driven fault detector. This particular fault detection and isolation approach was implemented at TEKOB1 Kostolac Thermal Power Plant in Serbia, whose nominal power output is 330 MW.
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To robust identification of water Steam-Separator process in thermal power plants
2012 IEEE International Conference on Industrial Technology, 2012Co-Authors: Goran Kvaščev, Aleksandra Marjanovic, Predrag Tadic, Zeljko DjurovicAbstract:One of the primary requirements for a high performance process control is a good quality and reliability of obtained measurements. In order to overcome the problem of sporadic high-intensity irregular measurements (outliers) presence, a robust process identification procedure must be used. The paper presents an application of an adaptive approach to robust parameter estimation of a linear dynamic discrete-time system, based on QQ-plot method together with robustified winsorization technique. The proposed procedure is implemented in a stem Separator system in thermal power plants. The comparison to the conventional RLS approach demonstrates the effectiveness of this method in the presence of impulse noise.
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Applications of predictive maintenance techniques in industrial systems
Serbian Journal of Electrical Engineering, 2011Co-Authors: Aleksandra Marjanovic, Predrag Tadic, Goran Kvaščev, Zeljko DjurovicAbstract:Prognostic methods represent a new methodology for system maintenance which offers significant time and cost savings. The paper offers a short overview of the available prognosis techniques and proposes the implementation of one model-based and one data-driven method. As a representative of the model-based methods the autoregressive moving average (ARMA) modeling approach is chosen. The estimated model parameters are further used for implementing the early change detector which is realized as a Neyman-Pearson hypothesis test. On the other hand, hidden Markov model (HMM) based prognosis illustrates the use of data-driven techniques. Using the cross-correlation input-output functions, HMM prognosis algorithm is proposed, as a suitable way of timely detection. Both techniques were implemented to detect performance changes of the water level sensor in a Steam Separator system in thermal power plants.
