Experimental Investigation of Natural-Circulation Flow Behavior under Low-Power/Low-Pressure Conditions in the Large-Scale PANDA Facility

2004 ◽  
Vol 148 (3) ◽  
pp. 294-312 ◽  
Author(s):  
Olivier Auban ◽  
Domenico Paladino ◽  
Robert Zboray
Keyword(s):  
Experimental Investigation ◽  
Low Power ◽  
Large Scale ◽  
Natural Circulation ◽  
Flow Behavior ◽  
Low Pressure ◽  
Circulation Flow

scholarly journals Large Scale Experiments Representing a Containment Natural Circulation Loop during an Accident Scenario

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
R. Kapulla ◽  
G. Mignot ◽  
S. Paranjape ◽  
M. Andreani ◽  
D. Paladino
Keyword(s):  
Large Scale ◽  
Natural Circulation ◽  
Phase 1 ◽  
Hydrogen Release ◽  
Circulation Loop ◽  
Mitigation Measures ◽  
Normal Operation ◽  
Circulation Flow ◽  
Small Aperture ◽  
Natural Circulation Loop

The assessment of hydrogen release, distribution, and mitigation measures in the containment of a nuclear power plant is increasingly based on code calculations. These calculations require state-of-the-art experiments to benchmark the codes against them. Two of these experiments are presented in this paper. These experiments were conducted in the PANDA facility (Switzerland) in the framework of the OECD/NEA HYMERES project. The experiments consider natural circulation flow in a two-room type containment where flow loops can form between the inner and the outer zones. During normal operation these zones are separated and in the case of an accident they become either connected by the opening of rupture disks, convective foils, and dampers or connected by bursting of doors and opening of other connections between compartments. For the experiments considered here one lower PANDA-vessel represents the steam generator (SG) tower and the inaccessible area whereas the other vessel represents the outer room area. The lower vessels are isolated from one another except for a small aperture that represents the damper. The two upper vessels—representing the containment dome—are connected to the lower vessels through tubes. The scenario consisted of four phases. In phase 1, a high steam mass flow rate was injected in the vessel representing the SG tower. After the relaxation phase 2, helium (representing hydrogen) was injected in the same vessel (phase 3). Finally in phase 4 no active interventions were done until the end of the test. Two tests were conducted to evaluate the developing helium transport by the natural circulation flow: one with and one without damper (by closing the aperture). The results showed that a two-room containment (TRC) mixing scenario can be well represented with the PANDA facility. It is found that, with the mixing damper open, a global natural circulation loop develops over all four vessels, whereas with closed damper the natural circulation loop is established only between the three vessels representing the inner zone and the upper dome. It is shown that the presence of the damper has a strong effect on the resulting helium content in the inner zone with 3 times less helium at the end of the test compared with the configuration without damper. The formation of a stable helium stratification in the upper vessels was observed in the presence of the open damper.

Experimental and Modeling Studies on Pressure Gradient Prediction for Horizontal Gas Wells Based on Dimensionless Number Analysis

2021 ◽  
Author(s):  
Chengcheng Luo ◽  
Ning Wu ◽  
Sha Dong ◽  
Yonghui Liu ◽  
Changqing Ye ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Pressure Gradient ◽  
Flow Behavior ◽  
Scaling Up ◽  
Low Pressure ◽  
Dimensionless Number ◽  
Gas Wells ◽  
Liquid Holdup ◽  
Dimensionless Numbers ◽  
New Model

Abstract Accurate prediction of pressure gradient in gas wells is the theoretical basis of gas well performance analysis, production optimization and deliquification technologies design. Experiment is the best access to characterize the flow behavior of gas wells. For low-pressure experimental investigation and gas wells, the most difference is the pressure (gas density), which could lead to totally different flow behavior. Dimensionless numbers are often used in the flow pattern maps to account for the flow similarities at different conditions, which means liquid holdup in the high pressure can be also predicted at low pressure conditions if we choose proper dimensionless numbers for pressure scaling up. However, no studies have focused on this point before. Besides, gas wells have high GLR, most empirical models were intended to developed for oil wells, which have greater weight in low GLR, decreasing the accuracy in gas wells. In order to predict the pressure gradient in horizontal gas wells, an experimental investigation of gas-water flow has been conducted. The experimental test matrix was designed to cover all the flow patterns. The experiment was conducted in a 5-m long pipe. The liquid holdup and pressure gradient were measured. Subsequently, the effect of gas velocity, liquid velocity, pipe diameter, and inclined angle on liquid holdup was analyzed. Then the dimensionless numbers proposed in the literature have been investigated and analyzed for pressure scaling up. Finally, a comprehensive model was established, which is developed for prediction pressure drop in gas wells. Some field and experimental data were provided to evaluate the new model. The results show that the Duns-Ros dimensionless number was not proper for pressure scaling up while the Hewitt-Robert Number performs best. Compared to widely used pressure gradient models with field data, the new model with Hewitt-Robert Number performed best, which shows that it is capable of dealing with prediction of pressure gradient in gas wells.

scholarly journals Natural Circulation Characteristics at Low-Pressure Conditions through PANDA Experiments and ATHLET Simulations

2008 ◽  
Vol 2008 ◽  
pp. 1-14 ◽  
Author(s):  
Domenico Paladino ◽  
Max Huggenberger ◽  
Frank Schäfer
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Natural Circulation ◽  
Low Pressure ◽  
Operating Conditions ◽  
Quality Data ◽  
Experimental Investigations ◽  
Stability Performance ◽  
Wide Range ◽  
Circulation Characteristics

Natural circulation characteristics at low pressure/low power have been studied by performing experimental investigations and numerical simulations. The PANDA large-scale facility was used to provide valuable, high quality data on natural circulation characteristics as a function of several parameters and for a wide range of operating conditions. The new experimental data allow for testing and improving the capabilities of the thermal-hydraulic computer codes to be used for treating natural circulation loops in a range with increased attention. This paper presents a synthesis of a part of the results obtained within the EU-Project NACUSP “natural circulation and stability performance of boiling water reactors.” It does so by using the experimental results produced in PANDA and by showing some examples of numerical simulations performed with the thermal-hydraulic code ATHLET.

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