Two-phase flow phenomena along an adiabatic riser – An experimental study at the test-facility GENEVA

Cloppenborg, Tim; Schuster, C.; Hurtado, Antonio

doi:10.1016/j.ijmultiphaseflow.2015.02.003

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…The phase difference of the temperature between the heated and the adiabatic section is similar and the dwell time of the fluid and the oscillation period is nearly the same [111]. This phenomenon was experimentally investigated by many researchers such as Schuster [112][113][114], Furuya et al [5,115], Manera [116,117] and Cloppenborg [98,99].…”

Section: Density Wave Oscillationmentioning

confidence: 96%

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Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome BWR Reactor KERENA: Part II

et al. 2019

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Passive safety systems are an important feature of currently designed and constructed nuclear power plants. They operate independent of external power supply and manual interventions and are solely driven by thermal gradients and gravitational force. This brings up new needs for performance and reliably assessment. This paper provides a review on fundamental approaches to model and analyze the performance of passive heat removal systems exemplified for the passive heat removal chain of the KERENA boiling water reactor concept developed by Framatome. We discuss modeling concepts for one-dimensional system codes such as ATHLET, RELAP and TRACE and furthermore for computational fluid dynamics codes. Part I dealt with numerical and experimental methods for modeling of condensation inside the emergency condenser and on the containment cooling condenser. This second part deals with boiling and two-phase flow instabilities.

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Section: Density Wave Oscillationmentioning

confidence: 96%

“…In 2007, Marcel [97] observed only geysering instabilities in the test-facility CIRCUS with a parallel chimney configuration. At low pressure, the phenomenon was observed to be the most prevalent during the investigations on the open natural circulation test facility GENEVA by Cloppenborg et al [98].…”

Section: Geyseringmentioning

confidence: 96%

Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome BWR Reactor KERENA: Part II

et al. 2019

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“…Because of its importance in nuclear safety analysis, FII has gained much attention by means of both numerical and experimental investigations [20][21][22][23][24][25][26][27]. The experiment for the present study refers to the work of Cloppenborg et al [28], conducted at GENEVA at Dresden University of Technology, which is a semi-open natural-circulation test facility with water as the working fluid. It is built to analyze the instability behavior in the KERENA TM reactor containment cooling condenser (CCC) system [7].…”

Section: Test Facility and Boundary Conditions Of Computational Domainmentioning

confidence: 99%

CFD Modeling of Phase Change during the Flashing-Induced Instability in a Natural Circulation Circuit

Liao

Lucas

2023

Processes

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Flashing-induced instability (FII) has a significant impact on the safe operation of a natural circulation circuit, a phenomenon frequently encountered in the cooling systems of advanced light water reactors. While one-dimensional system codes are commonly used for the engineering design and safety analysis of FII, there is a strong academic interest in understanding the underlying physical mechanisms. To address this, high-resolution computational fluid dynamics (CFD) simulations serve as a valuable tool. However, the current state of CFD modeling for two-phase flows with phase change, which are particularly highly transient fluctuating flashing flows, is still in its early stages of development. In this study, we establish a CFD model that focuses on interphase heat transfer to analyze the phase change during FII. By incorporating experimental data from the literature, we investigate the transient flow field and thermodynamic behavior in the riser of the GENEVA test facility. The study provides valuable insights into the non-equilibrium and interfacial transfer phenomena during the phase change as well as the effect of high-frequency fluctuation. Additionally, we discuss in detail the challenges associated with FII modeling and the limitations of the current model. We also provide suggestions for potential improvements in future numerical studies. The results show that the thermal phase change and heat transfer coefficient model adopted for the simulation reasonably captures the evaporation and condensation process. However, it tends to under-predict the evaporation rate, which results in a larger pressure drop through the riser. The observation that the void fraction close to the wall is higher than that in the riser center evidences that the reliable modeling of bubble size distribution as well as the inclusion of non-drag forces are important for predicting the transverse void distribution. Furthermore, it reveals that both the temperature and pressure change in an FII, and their effects on phase change should be taken into account simultaneously.

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“…In 2012, Cloppenborg et al (2015) set up the test facility GENEVA to investigate the system and stability behavior of the passive containment cooling condenser (cf. Fig.…”

Section: Test Facility Genevamentioning

confidence: 99%

“…Within the scope of the previous investigation, Cloppenborg et al (2015) measured the mass flow inside the test circuit as well as the pressure and fluid temperature at the inlet of the heat transfer tube and the fluid temperature at the tube outlet. Regarding the heat source circuit, the steam mass flow, the pressure inside the steam chamber, and the steam temperature were measured parameters.…”

Section: Instrumentationmentioning

confidence: 99%

Experimental and theoretical investigation of the boiling heat transfer in a low-pressure natural circulation system

Viereckl

Schleicher

Schuster

et al. 2019

Exp. Comput. Multiph. Flow

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The implementation of passive safety systems in nuclear reactors provides the opportunity to enhance the nuclear safety. On the other hand, an accurate and reliable prediction of the heat removal behavior is not ensured because the operating conditions of certain types of passive systems like containment cooling systems differ from the validity ranges of the established heat transfer correlations. Therefore, a generic and detailed investigation is still necessary for passive systems. Against this background, the test facility GENEVA was erected at Technische Universität Dresden in 2012. Since the commissioning, generic experiments concerning the system and stability behavior of this facility, which emulate a low-pressure and low-flow (LPLF) natural circulation system, were provided. Nevertheless, the investigation of the heat transfer behavior remained an open issue. On this account, the instrumentation in the heat transfer region inside GENEVA was improved to gather the necessary temperature and void fraction profiles. The performed experiments provide a generic and wide database concerning boiling in a LPLF natural circulation systems. Within this paper, the development of the wall and bulk fluid temperature as well as the axial and center line void fraction profile in a slightly inclined tube for different heat flow rates are discussed. Furthermore, flow patterns could be identified on behalf of the void fraction measurements. To conclude the experimental analysis, the development of the heat transfer coefficient was estimated. These experimental data provide the basis for a simulation with the lumped-parameter thermal-hydraulic code ATHLET and serve as validation reference. However, the comparisons between the experimental and computational results show insufficient agreements. Mainly, the simulation misses the saturation point of the experiments, which leads to great differences of the void fraction values. Moreover, inaccuracies appear as well with the heat transfer coefficient. The experimental and computational results that are discussed in this paper provide the basis for the advancement not only of heat transfer correlations but also of flow pattern maps within the range of low pressure natural circulation system. In summary, this investigation contributes to the general purpose to enhance nuclear safety by providing an accurate and reliable prediction of the heat removal capacity of passive systems.

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Two-phase flow phenomena along an adiabatic riser – An experimental study at the test-facility GENEVA

Cited by 11 publications

References 21 publications

Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome BWR Reactor KERENA: Part II

Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome BWR Reactor KERENA: Part II

CFD Modeling of Phase Change during the Flashing-Induced Instability in a Natural Circulation Circuit

Experimental and theoretical investigation of the boiling heat transfer in a low-pressure natural circulation system

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