BCC-Fe is the critical and major component of the reactor pressure vessel (RPV) steel. With long-tern neutron irradiation, many point defects can be obtained in RPV steel. In this paper, the points defects (interstitial, vacancy and Frenkel pair) effects on the tensile strength of Fe are studied by molecular dynamics simulations at 300K. The uni-axial tensile load is along [001] direction of the Fe samples loading in constant strain rate. The Fe atoms are added or removed randomly to generate point defects. For point defects, three types of point defects can decrease the tensile strength containing yield stress and strain of Fe samples. In addition, the tensile strength decreases with the increase of point defect concentration. With the same defect concentration, interstitials decrease the yield stress the most seriously compared with the vacancies and Frenkel pairs. Apart from that, the morphology and evolution of the microstructure of Fe with point defects are also investigated under tension. Compared with the perfect crystal, the generation of dislocation decreases the tensile strength dramatically. For sample with interstitials, interstitial clusters form and evolve in dislocations loops finally. For sample with vacancis, vacancy may aggregate together and vacancy clusters form as a result, which is seen as precursors of dislocation loop. Notably, the results are meaningful to understand the effects of point defects on tensile strength of BCC-Fe.
{"title":"Point Defect Effects on Tensile Strength of BCC-Fe Studied by Molecular Dynamics","authors":"P. Lin, Nie Junfeng, Meidan Liu","doi":"10.1115/icone2020-16162","DOIUrl":"https://doi.org/10.1115/icone2020-16162","url":null,"abstract":"\u0000 BCC-Fe is the critical and major component of the reactor pressure vessel (RPV) steel. With long-tern neutron irradiation, many point defects can be obtained in RPV steel. In this paper, the points defects (interstitial, vacancy and Frenkel pair) effects on the tensile strength of Fe are studied by molecular dynamics simulations at 300K. The uni-axial tensile load is along [001] direction of the Fe samples loading in constant strain rate. The Fe atoms are added or removed randomly to generate point defects. For point defects, three types of point defects can decrease the tensile strength containing yield stress and strain of Fe samples. In addition, the tensile strength decreases with the increase of point defect concentration. With the same defect concentration, interstitials decrease the yield stress the most seriously compared with the vacancies and Frenkel pairs. Apart from that, the morphology and evolution of the microstructure of Fe with point defects are also investigated under tension. Compared with the perfect crystal, the generation of dislocation decreases the tensile strength dramatically. For sample with interstitials, interstitial clusters form and evolve in dislocations loops finally. For sample with vacancis, vacancy may aggregate together and vacancy clusters form as a result, which is seen as precursors of dislocation loop. Notably, the results are meaningful to understand the effects of point defects on tensile strength of BCC-Fe.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121133362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haomin Sun, Yohan Leblois, T. Gelain, E. Porcheron
During a severe accident of a pressurized water reactor (PWR), fission products (FPs) may be released and transported to the containment. The containment spray can be utilized to remove the aerosols of FPs, which contributes to retaining the FPs in the sump. Therefore, it is important to develop an analytical model for predicting the aerosol removal efficiency by the containment spray for nuclear safety. The containment spray is required to have a very high spray coverage ratio where the droplets are expected to impact the containment side walls. In such condition, the gas flow induced by the droplets will behave differently from that in the other condition without the droplet impaction where a stable gas circulation is expected between the boundary of the spray and the side walls. Since the aerosol removal efficiency also depends on the gas flow behavior, to develop the aerosol removal model applicable for the containment spray from this viewpoint, several aerosol removal experiments were carried out in the TOSQAN IRSN facility. Based on the droplet mass flux measurements, it was confirmed that the spray coverage ratios were comparable to that of the containment spray and many droplets impacted the side wall. According to the aerosol measurement results, it was found the aerosol removal was more effective in higher spray water flow rates. Since larger particles were removed more quickly, the mean particle diameter was decreasing during the spray operation and approached to a value. Based on a CFD simulation for the experiment, gas velocity field was investigated. The measured and calculated particle number concentration decays agreed well.
{"title":"Experimental Study on Aerosol Collection by Spray Droplets: Application to Fission Products Removal in Containment","authors":"Haomin Sun, Yohan Leblois, T. Gelain, E. Porcheron","doi":"10.1115/icone2020-16857","DOIUrl":"https://doi.org/10.1115/icone2020-16857","url":null,"abstract":"\u0000 During a severe accident of a pressurized water reactor (PWR), fission products (FPs) may be released and transported to the containment. The containment spray can be utilized to remove the aerosols of FPs, which contributes to retaining the FPs in the sump. Therefore, it is important to develop an analytical model for predicting the aerosol removal efficiency by the containment spray for nuclear safety. The containment spray is required to have a very high spray coverage ratio where the droplets are expected to impact the containment side walls. In such condition, the gas flow induced by the droplets will behave differently from that in the other condition without the droplet impaction where a stable gas circulation is expected between the boundary of the spray and the side walls. Since the aerosol removal efficiency also depends on the gas flow behavior, to develop the aerosol removal model applicable for the containment spray from this viewpoint, several aerosol removal experiments were carried out in the TOSQAN IRSN facility. Based on the droplet mass flux measurements, it was confirmed that the spray coverage ratios were comparable to that of the containment spray and many droplets impacted the side wall. According to the aerosol measurement results, it was found the aerosol removal was more effective in higher spray water flow rates. Since larger particles were removed more quickly, the mean particle diameter was decreasing during the spray operation and approached to a value. Based on a CFD simulation for the experiment, gas velocity field was investigated. The measured and calculated particle number concentration decays agreed well.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124308128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vertical upward two-phase flows in annulus are of great importance in many industrial fields due to the closely relationship between the flow patterns and the heat transfer characteristics. Common flow patterns in annulus are bubbly (B), slug (S), churn (C) and annular (A) flow, most of which are quite similar to those in tubes. However, due to the elliptic nose and asymmetric shape of the Taylor bubble in annulus, the slug to churn flow transition could be influenced by the channel geometry which was usually ignored in most of the previous researches. The flow pattern transition criteria for tubes are thus not applicable for annulus, especially for slug to churn flow transition, which should be separately studied. Therefore, in this paper, the basic characteristics of the flow pattern in annulus and their transition mechanism are analyzed. In addition, a set of semi-empirical transition criteria with higher accuracy are assessed and selected for annulus based on theoretical analysis and comparisons with experimental data.
{"title":"Flow Pattern Transition Criteria for Upward Two-Phase Flow in Annulus","authors":"He Wen, Zhao Chenru, Bo Hanliang","doi":"10.1115/icone2020-16174","DOIUrl":"https://doi.org/10.1115/icone2020-16174","url":null,"abstract":"\u0000 Vertical upward two-phase flows in annulus are of great importance in many industrial fields due to the closely relationship between the flow patterns and the heat transfer characteristics. Common flow patterns in annulus are bubbly (B), slug (S), churn (C) and annular (A) flow, most of which are quite similar to those in tubes. However, due to the elliptic nose and asymmetric shape of the Taylor bubble in annulus, the slug to churn flow transition could be influenced by the channel geometry which was usually ignored in most of the previous researches. The flow pattern transition criteria for tubes are thus not applicable for annulus, especially for slug to churn flow transition, which should be separately studied. Therefore, in this paper, the basic characteristics of the flow pattern in annulus and their transition mechanism are analyzed. In addition, a set of semi-empirical transition criteria with higher accuracy are assessed and selected for annulus based on theoretical analysis and comparisons with experimental data.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124291450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Lewandowski, Paul J. Kristo, Abdullah G. Weiss, M. Kimber
In this study, the well understood single round jet in crossflow is compared to an array of three jets aligned on the central axis of the crossflow, all of which are distinct with independent temperature and flow control. The benefit of this study is to better understand how an array of jets mix with a crossflow in turbulent conditions in an effort to further validate computation models for a variety of multiple-jet applications. The test section involves jets issuing vertically downward into a cross flow provided by a low speed wind tunnel. The jets are spaced two diameters apart, providing for an upstream, middle, and downstream jet. The hydraulic interactions are tracked via a stereoscopic particle image velocimetry (S-PIV) system. Several reference measurements and the uncertainty of the results are discussed to aid analogous computational fluid dynamics (CFD) models in the future. First order statistics between the single and triple jet cases with fixed flow rates are compared. Temporal analysis yields dominant frequencies at distinct regions within the flow. Insights into flow control of multiple jets in a cross flow is discussed. The experimental data sets compare the classical single jet in cross flow to the extension of multiple jets. Several differences in the flow behavior are found. The data sets serve as benchmark cases for future CFD models that will aim to replicate these flow types in different real-world applications such as coolant flows in a gas cooled reactor.
{"title":"Comparison of the Behavior of Different Jet Configurations in a Crossflow","authors":"M. Lewandowski, Paul J. Kristo, Abdullah G. Weiss, M. Kimber","doi":"10.1115/icone2020-16655","DOIUrl":"https://doi.org/10.1115/icone2020-16655","url":null,"abstract":"\u0000 In this study, the well understood single round jet in crossflow is compared to an array of three jets aligned on the central axis of the crossflow, all of which are distinct with independent temperature and flow control. The benefit of this study is to better understand how an array of jets mix with a crossflow in turbulent conditions in an effort to further validate computation models for a variety of multiple-jet applications. The test section involves jets issuing vertically downward into a cross flow provided by a low speed wind tunnel. The jets are spaced two diameters apart, providing for an upstream, middle, and downstream jet. The hydraulic interactions are tracked via a stereoscopic particle image velocimetry (S-PIV) system. Several reference measurements and the uncertainty of the results are discussed to aid analogous computational fluid dynamics (CFD) models in the future. First order statistics between the single and triple jet cases with fixed flow rates are compared. Temporal analysis yields dominant frequencies at distinct regions within the flow. Insights into flow control of multiple jets in a cross flow is discussed. The experimental data sets compare the classical single jet in cross flow to the extension of multiple jets. Several differences in the flow behavior are found. The data sets serve as benchmark cases for future CFD models that will aim to replicate these flow types in different real-world applications such as coolant flows in a gas cooled reactor.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123415736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the nuclear field, the reactor using plate fuel assembly forms multiple jets at exit. So, it’s meaningful to study multiple jets to learn the behavior of the coolant when it leaves the core. This paper uses PIV technology to study the flow characteristics of 9 jets at low Reynolds number. Firstly, the velocity field reveals that the pressure outside the jet is greater than the inside of the jet, which causes the jet to deflect and converge inward at z/w = 0–8. Then, the velocity field with different Re number is analyzed in the center plane, and find that the flow distribution is similar. Then, a detailed analysis is performed on the jet under specific conditions, and the merge point is discussed in the paper. At the same time, the first-order velocity tensor are also calculated in this paper. In addition, this article also analyzes the jet flow field after the central narrow channel was blocked. In this experiment, a plug was used to block the No. 5 jet by 1/3. And the flow redistribution is discussed in this case. The methods of flow calculation using PIV technology is established and compared with the real number of flowmeters, it’s found that the calculation method is rather accurate. On the other hand, the experiment find that the distribution of flow in each channel is not uniform, and the blocking condition make an increase in the flow of edge channels, which leads to the decreasing of flow in the blocked adjacent channel.
{"title":"Experimental Study on Multi-Channel Jets in Plate Assembly Under Blockage Condition","authors":"Hu Huijian, Wang Peng, Li Dongyang, Sichao Tan","doi":"10.1115/icone2020-16955","DOIUrl":"https://doi.org/10.1115/icone2020-16955","url":null,"abstract":"\u0000 In the nuclear field, the reactor using plate fuel assembly forms multiple jets at exit. So, it’s meaningful to study multiple jets to learn the behavior of the coolant when it leaves the core. This paper uses PIV technology to study the flow characteristics of 9 jets at low Reynolds number. Firstly, the velocity field reveals that the pressure outside the jet is greater than the inside of the jet, which causes the jet to deflect and converge inward at z/w = 0–8. Then, the velocity field with different Re number is analyzed in the center plane, and find that the flow distribution is similar. Then, a detailed analysis is performed on the jet under specific conditions, and the merge point is discussed in the paper. At the same time, the first-order velocity tensor are also calculated in this paper. In addition, this article also analyzes the jet flow field after the central narrow channel was blocked. In this experiment, a plug was used to block the No. 5 jet by 1/3. And the flow redistribution is discussed in this case. The methods of flow calculation using PIV technology is established and compared with the real number of flowmeters, it’s found that the calculation method is rather accurate. On the other hand, the experiment find that the distribution of flow in each channel is not uniform, and the blocking condition make an increase in the flow of edge channels, which leads to the decreasing of flow in the blocked adjacent channel.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116413613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fuel Coolant Interaction (FCI), one of the critical phenomena in severe accident, involves a variety of physical phenomena including the interaction between coolant and fuel of high temperature. Especially, the jet break-up of a pre-mixing phase that the bulk of molten fuel breaks into the droplet is important for the accident progression. Understanding the intricate physics of jet break-up is essential to reduce the uncertainties of FCI and to mitigate severe accident. In this study, we have developed Lagrangian-based CFD code (named as SOPHIA) using Smoothed Particle Hydrodynamics (SPH) method, which has an advantage on handling the complicated interfacial behaviors, large deformation and multiphase flow. Furthermore, the SOPHIA code is parallelized on the multi-GPUs to achieve high-resolution and large-scale simulation that enhance the accuracy and practical applicability. Using the multi-GPU based SOPHIA code, this study simulates the benchmark jet breakup experiments in high resolution and three dimensions. The simulation results are compared with the experimental data both qualitatively and quantitatively. As a results, they shows a good agreement, and furthermore, three dimensional high resolution simulation is confirmed to resolve the physical features of jet breakup accurately by taking account into the multi-fluids interactions between jet-pool-air.
{"title":"High Resolution 3D Simulation of Melt Jet Breakup Phenomenon Using Multi-GPU-Based Smoothed Particle Hydrodynamics Code and Comparison With Experimental Result","authors":"Sohyun Park, Y. Jo, E. Kim","doi":"10.1115/icone2020-16433","DOIUrl":"https://doi.org/10.1115/icone2020-16433","url":null,"abstract":"\u0000 Fuel Coolant Interaction (FCI), one of the critical phenomena in severe accident, involves a variety of physical phenomena including the interaction between coolant and fuel of high temperature. Especially, the jet break-up of a pre-mixing phase that the bulk of molten fuel breaks into the droplet is important for the accident progression. Understanding the intricate physics of jet break-up is essential to reduce the uncertainties of FCI and to mitigate severe accident. In this study, we have developed Lagrangian-based CFD code (named as SOPHIA) using Smoothed Particle Hydrodynamics (SPH) method, which has an advantage on handling the complicated interfacial behaviors, large deformation and multiphase flow. Furthermore, the SOPHIA code is parallelized on the multi-GPUs to achieve high-resolution and large-scale simulation that enhance the accuracy and practical applicability. Using the multi-GPU based SOPHIA code, this study simulates the benchmark jet breakup experiments in high resolution and three dimensions. The simulation results are compared with the experimental data both qualitatively and quantitatively. As a results, they shows a good agreement, and furthermore, three dimensional high resolution simulation is confirmed to resolve the physical features of jet breakup accurately by taking account into the multi-fluids interactions between jet-pool-air.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115798025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Xiaobo, Chang-qi Yan, Fan Guangming, Jie Cheng, Xu Junxiu, Antai Liu
Gas-liquid separation is widely used in many fields, such as nuclear energy and petroleum resources. And the gas-liquid mixture separated gradually shows the characteristic of wide range of gas void fraction and variable flow patterns. However, the current separators only suit for narrow range of gas void fraction or single flow patterns. In this research, two different new type separators using centrifugal technology were designed and an experimental system was constructed to test the two separators using dry air and water under different flow patterns, including bubble, slug and churn flow. One was called inline separator consisting of three swirls and another was called double-layer cylinder separator composed of a central tube, a swirl and an outer tube. The results show that the separation performance of the inline separator was sensitive to flow patterns and the two-layer cylinder separator keeps high efficiency in different flow patterns. In bubble flow and slug flow patterns, the two separators kept high efficiency, while the oscillation of the gas core in the inline separator aggravated under slug flow condition. When increasing the gas void fraction, the turbulence of the churn flow led to the diameter of the gas core change drastically and reduce separation efficiency significantly.
{"title":"Experimental Study on Two Different Gas-Liquid Separators Under Different Flow Patterns","authors":"Z. Xiaobo, Chang-qi Yan, Fan Guangming, Jie Cheng, Xu Junxiu, Antai Liu","doi":"10.1115/icone2020-16297","DOIUrl":"https://doi.org/10.1115/icone2020-16297","url":null,"abstract":"\u0000 Gas-liquid separation is widely used in many fields, such as nuclear energy and petroleum resources. And the gas-liquid mixture separated gradually shows the characteristic of wide range of gas void fraction and variable flow patterns. However, the current separators only suit for narrow range of gas void fraction or single flow patterns. In this research, two different new type separators using centrifugal technology were designed and an experimental system was constructed to test the two separators using dry air and water under different flow patterns, including bubble, slug and churn flow. One was called inline separator consisting of three swirls and another was called double-layer cylinder separator composed of a central tube, a swirl and an outer tube. The results show that the separation performance of the inline separator was sensitive to flow patterns and the two-layer cylinder separator keeps high efficiency in different flow patterns. In bubble flow and slug flow patterns, the two separators kept high efficiency, while the oscillation of the gas core in the inline separator aggravated under slug flow condition. When increasing the gas void fraction, the turbulence of the churn flow led to the diameter of the gas core change drastically and reduce separation efficiency significantly.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126372070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu Huiyu, G. Hai-feng, Chen Junyan, Sun Zhong-ning
The containment spray system is of great importance for the nuclear power plant to reduce the pressure and temperature, as well as concentration of radioactive aerosols released from reactor core under the severe accident. The main aim of present study is to develop a simplified model for aerosol removal by spray system, the model is employed to predict the variation of aerosol concentration in containment and reveal the key mechanism influencing aerosol removal. In the present model, the air flow entrained by spraying droplet is considered which is computed by solving simplified one-dimension momentum equations rather than the standard N-S equation. For the validation of the model, a small size sprinkle experiment facility is built. The facility is equipped with non-intrusive instruments such as particle size spectrometer for aerosol spectrum measurement, HELOS/R for measuring the droplet spectrum. The result of aerosol removal of the present model is compared with the result of the full coverage model and the experimental result. In the experiment, polydisperse aerosol is used and the removal rate of aerosols with different sizes is compared against the result of the present model and the full coverage model. The velocity of entrained gas flow and the distribution of droplets are displayed. The computational result reveals the aerosol removal constant distribution along the height.
{"title":"Development of a Simplified Model for Aerosol Removal by Spray System of Containment","authors":"Yu Huiyu, G. Hai-feng, Chen Junyan, Sun Zhong-ning","doi":"10.1115/icone2020-16353","DOIUrl":"https://doi.org/10.1115/icone2020-16353","url":null,"abstract":"\u0000 The containment spray system is of great importance for the nuclear power plant to reduce the pressure and temperature, as well as concentration of radioactive aerosols released from reactor core under the severe accident. The main aim of present study is to develop a simplified model for aerosol removal by spray system, the model is employed to predict the variation of aerosol concentration in containment and reveal the key mechanism influencing aerosol removal. In the present model, the air flow entrained by spraying droplet is considered which is computed by solving simplified one-dimension momentum equations rather than the standard N-S equation. For the validation of the model, a small size sprinkle experiment facility is built. The facility is equipped with non-intrusive instruments such as particle size spectrometer for aerosol spectrum measurement, HELOS/R for measuring the droplet spectrum. The result of aerosol removal of the present model is compared with the result of the full coverage model and the experimental result. In the experiment, polydisperse aerosol is used and the removal rate of aerosols with different sizes is compared against the result of the present model and the full coverage model. The velocity of entrained gas flow and the distribution of droplets are displayed. The computational result reveals the aerosol removal constant distribution along the height.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126175108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sunil Kumar, P. Vijayan, R. Grover, Umasankari Kannan, H. Yadav, Abhijit Agrawal
Advanced nuclear reactors use large pool of water inventory with an immersed heat exchanger to remove decay heat especially in the case of Station Black Out (SBO). The isolation condenser (IC) immersed in Gravity Driven Water Pool (GDWP) of Advanced Heavy Water Reactor (AHWR) is an example of such systems. Heat rejected by the IC is absorbed in the pool. As a result, water density decreases and moves towards the free surface of pool causing layers of hot water piling up over colder one giving rise to stratified water inventory. consequently, the pool at the free surface starts boiling before the grace period (7 days). In the present paper, thermal stratification has been modeled in a power to volume scaled experimental setup. The study is focused on investigating the effect of heater orientation on suppression of thermal stratification in the pool for both the cases of with and without shrouds around heat exchanger.
{"title":"Experimental Investigations on Thermal Stratification in a Large Pool of Water With Immersed Isolation Condenser","authors":"Sunil Kumar, P. Vijayan, R. Grover, Umasankari Kannan, H. Yadav, Abhijit Agrawal","doi":"10.1115/icone2020-16647","DOIUrl":"https://doi.org/10.1115/icone2020-16647","url":null,"abstract":"\u0000 Advanced nuclear reactors use large pool of water inventory with an immersed heat exchanger to remove decay heat especially in the case of Station Black Out (SBO). The isolation condenser (IC) immersed in Gravity Driven Water Pool (GDWP) of Advanced Heavy Water Reactor (AHWR) is an example of such systems. Heat rejected by the IC is absorbed in the pool. As a result, water density decreases and moves towards the free surface of pool causing layers of hot water piling up over colder one giving rise to stratified water inventory. consequently, the pool at the free surface starts boiling before the grace period (7 days). In the present paper, thermal stratification has been modeled in a power to volume scaled experimental setup. The study is focused on investigating the effect of heater orientation on suppression of thermal stratification in the pool for both the cases of with and without shrouds around heat exchanger.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133790098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kun Cheng, Jian Deng, R. Cai, Libo Qian, Peiyao Qi, Bingzheng Ke
The effects of rolling condition on the flow instability characteristics of natural circulation (NC) in rod bundle channel were experimentally studied. A 3 × 3 rod bundle channel is used as the testing section. The experimental system pressure range is 0.2 to 0.6 MPa, and the range of inlet subcooling is 10 to 70 °C. The ranges of rolling motion amplitude and period are 10 ∼ 20° and 10 ∼ 30s, respectively. Two typical two-phase flow instabilities in rod bundle channel under rolling condition were found in experiments: (a) the trough-type oscillation caused by the vapor generation at the minimum point of flow fluctuation and (b) the compound oscillation formed by the superposition of the trough-type oscillation and DWOI. Experimental results show that the rolling motion can reduce the threshold heating power of trough-type oscillation and cause the occurrence of NC flow instability in advance. But the rolling motion cannot affect the dimensionless boundary of DWOI in rod bundle channel.
{"title":"Study on Natural Circulation Flow Instabilities in Rod Bundle Channel Under Rolling Condition","authors":"Kun Cheng, Jian Deng, R. Cai, Libo Qian, Peiyao Qi, Bingzheng Ke","doi":"10.1115/icone2020-16362","DOIUrl":"https://doi.org/10.1115/icone2020-16362","url":null,"abstract":"\u0000 The effects of rolling condition on the flow instability characteristics of natural circulation (NC) in rod bundle channel were experimentally studied. A 3 × 3 rod bundle channel is used as the testing section. The experimental system pressure range is 0.2 to 0.6 MPa, and the range of inlet subcooling is 10 to 70 °C. The ranges of rolling motion amplitude and period are 10 ∼ 20° and 10 ∼ 30s, respectively. Two typical two-phase flow instabilities in rod bundle channel under rolling condition were found in experiments: (a) the trough-type oscillation caused by the vapor generation at the minimum point of flow fluctuation and (b) the compound oscillation formed by the superposition of the trough-type oscillation and DWOI. Experimental results show that the rolling motion can reduce the threshold heating power of trough-type oscillation and cause the occurrence of NC flow instability in advance. But the rolling motion cannot affect the dimensionless boundary of DWOI in rod bundle channel.","PeriodicalId":414088,"journal":{"name":"Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130918446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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