Characteristics of Downcomer Boiling Phenomena During the Reflood Phase of a Postulated Large Break LOCA for the APR1400

2006 ◽  
Author(s):  
Byong-Jo Yun ◽  
Dong-Jin Euh ◽  
Won-Man Park ◽  
Young-Jung Youn ◽  
Chul-Hwa Song
Keyword(s):  
Two Phase Flow ◽  
Transient Behavior ◽  
Visual Observation ◽  
Test Facility ◽  
Phase Flow ◽  
Pressurized Water Reactor ◽  
Two Phase ◽  
Pressurized Water ◽  
Flow Parameters ◽  
Core Cooling

Downcomer boiling phenomena in a conventional pressurized water reactor have an important effect on the transient behavior of a postulated large-break LOCA (LBLOCA), because it can degrade the hydraulic head of the coolant in the downcomer and consequently affect the reflood flow rate for a core cooling. To investigate the thermal hydraulic behavior in the downcomer region, a test program for a downcomer boiling is being progressed in the reflood phase of a postulated LBLOCA. For this, the test facility was designed as a one side heated rectangular test section which adopts a full-pressure, full-height, and full-size downcomer-gap approach, but with the circumferential length reduced 47.08-fold. The test was performed by dividing it into two-phases: (I) visual observation and acquisition of the global two-phase flow parameters and (II) measurement of the local two-phase flow parameters on the measuring planes along five elevations. In the present paper, the test results of Phase-I and parts of Phase-II were introduced.

Interfacial behavior of the air-water counter-current two-phase flow in a 1/30 scale-down of pressurized water reactor (PWR) hot leg

2018 ◽  
Vol 116 ◽  
pp. 376-387
Author(s):  
Apip Badarudin ◽  
Andriyanto Setyawan ◽  
Okto Dinaryanto ◽  
Arif Widyatama ◽  
Indarto ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Pressurized Water Reactor ◽  
Interfacial Behavior ◽  
Two Phase ◽  
Pressurized Water ◽  
Water Reactor ◽  
Scale Down ◽  
Counter Current

Numerical Simulation of Flow Regime Transition From Slug to Wavy Flow in Helically Coiled Tubes

2016 ◽  
Author(s):  
Zhaoxu Li ◽  
Hongye Zhu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Centrifugal Force ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Pressurized Water Reactor ◽  
Two Phase ◽  
Pressurized Water

Two-phase flow in helically coiled tubes is becoming the interest of many investigators because of its importance in various applications, such as nuclear engineering, chemical engineering, refrigerating engineering and power engineering. Compared with U-type tubes used in pressurized water reactor (PWR), helically coiled tubes have advantages in size, heat transfer capacity, thermal stress toleration and two-phase stability. Accordingly the helically coiled tubes have been utilized in the steam generators of the next general reactors, such as gas-cooled reactor, fast breeder reactor and integrated pressurized water reactor. In helically coiled tubes the characteristics of momentum and heat transfer are distinct from those in straight tubes due to the presence of centrifugal force, especially for two-phase flow. Meanwhile, the transitions of flow regime, which is the crucial knowledge for the designers to determine the heat transfer rates and flow resistance, are also significantly affected by the centrifugal force. In this study, two-phase flow regimes in helically coiled tubes are investigated. Computational fluid dynamics (CFD), using fractional volume of fluid (VOF) model, is carried out to simulate wavy and slug flow regimes in helically coiled tubes. The corresponding experiment is also conducted to visualize these flow regimes at different superficial flow velocities. Numerical simulation results actually reflect the influence of centrifugal force on the two-phase flow and show a good agreement with the photographs captured from the experiment. Based on the simulations at different superficial flow velocities, the boundary between the slug and wavy flow regimes is predicted, in addition, compared with that in inclined tubes. The comparison indicates that centrifugal force could induce the appearance of wavy flows in advance and prompt the transition from slug flow to wavy flow.

scholarly journals The FAC Experimental Research on Vapor-water Two-phase Flow Piping System of CAP1400 Secondary Loop

2018 ◽  
Vol 207 ◽  
pp. 04001
Author(s):  
Shenhui Zhai ◽  
Simin Pang ◽  
Jie Shao ◽  
Hongqing Zhu ◽  
Xian Zhang ◽  
...  
Keyword(s):  
Power Plant ◽  
Two Phase Flow ◽  
Reactor Power ◽  
Test Facility ◽  
Piping System ◽  
Phase Flow ◽  
Corrosion Characteristic ◽  
Two Phase ◽  
Pressurized Water ◽  
Secondary Loop

CAP1400 power plant is one of the advanced Third-generation Pressurized Water Reactor power plant. To ensure the safety and stability of the power plant secondary loop during operation, the corrosion characteristic of CAP1400 secondary loop should been investigated. This paper set up a test facility to study the vapor-water two-phase flow corrosion status, which could be seen in the piping system after the control valve of heater drain line. The key parameters, such as pressure drop, temperature, and surface topography have been observed and measured, and the different corrosion characteristic in straight pipe, elbow, tee, and reducer also have been acquired in the tests. The test results and analysis could provide the basis for the corrosion resistance design of the drain pipelines in the CAP1400 nuclear power plant.

An Experimental Study on Liquid Film Dynamics and Interfacial Wave of Air-Water Two-Phase Flow in a Horizontal Channel

2013 ◽  
Author(s):  
Youjia Zhang ◽  
Weimin Ma ◽  
Shengjie Gong
Keyword(s):  
Liquid Film ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Research Work ◽  
Water Film ◽  
Test Facility ◽  
Phase Flow ◽  
Interfacial Wave ◽  
Film Rupture ◽  
Two Phase

This study is concerned with liquid film dynamics and stability of annular flow, which plays an important role in understanding film rupture and dryout in boiling heat transfer. The research work starts from designing and making a test facility which enables the visualization and measurement of liquid film dynamics. A confocal optical sensor is applied to track the evolution of film thickness. A horizontal rectangular channel made of glass is used as the test section. Deionized water and air are supplied into that channel in such a way that an initial stratified flow forms, with the liquid film on the bottom wall. The present study is focused on characterization of liquid film profile and dynamics in term of interfacial wave and shear force induced film rupture under adiabatic condition. Based on the experimental data and analysis, it is found that given a constant water flowrate, the average thickness of water film decreases with increasing air flowrate, while the interfacial wave of the two-phase flow is intensified. As the air flowrate reaches a critical value, a localized rupture of the water film occurs.

Interfacial Structures and Regime Transition in Co-Current Downward Bubbly Flow

2004 ◽  
Vol 126 (4) ◽  
pp. 528-538 ◽  
Author(s):  
S. Kim ◽  
S. S. Paranjape ◽  
M. Ishii ◽  
J. Kelly
Keyword(s):  
Two Phase Flow ◽  
Bubbly Flow ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Parameters ◽  
Interfacial Structures ◽  
Flux Model

The vertical co-current downward air-water two-phase flow was studied under adiabatic condition in round tube test sections of 25.4-mm and 50.8-mm ID. In flow regime identification, a new approach was employed to minimize the subjective judgment. It was found that the flow regimes in the co-current downward flow strongly depend on the channel size. In addition, various local two-phase flow parameters were acquired by the multi-sensor miniaturized conductivity probe in bubbly flow. Furthermore, the area-averaged data acquired by the impedance void meter were analyzed using the drift flux model. Three different distributions parameters were developed for different ranges of non-dimensional superficial velocity, defined by the ration of total superficial velocity to the drift velocity.

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