Computational study of instabilities in a rectangular natural circulation loop using 3D CFD simulation

Kudariyawar, Jayaraj Yallappa; Vaidya, A. M.; Maheshwari, N. K.; Satyamurthy, P.

doi:10.1016/j.ijthermalsci.2015.11.003

Cited by 37 publications

(6 citation statements)

References 25 publications

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“…The Fourier series based stability analysis described by Cammarata et al [2] was used by Lu et al [21] to obtain the stability map of an NCL system with heat flux (heat source) and constant temperature (heat sink) condition. A detailed 3-D CFD study of chaotic oscillations was conducted by Kudariyawar et al [22]. The physics of the uni-directional and bi-directional oscillations were presented, and a good agreement with the previous experimental work was reported.…”

Section: Chaotic Oscillations and Stability Analysis Of Ncl Systemssupporting

confidence: 59%

Stability analysis of a single-phase rectangular Coupled Natural Circulation Loop system employing a Fourier series based 1-D model

Dass,

Gedupudi

2020

Preprint

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A linear stability analysis of a single-phase Coupled Natural Circulation Loop (CNCL) is carried out using a Fourier series based 1-D model. A 3-D CFD study is undertaken to assess the ability of the 1-D model to capture the nonperiodic oscillatory behaviour exhibited by the CNCL system. After the model verification, the stability maps of the system are obtained from the eigenvalues of the steady-state. The CNCL has multiple steady states and the stability maps of consistently observed steady states are presented. A thorough parametric study is conducted to observe the influence of non-dimensional numbers on the CNCL system. Increase in the Fourier number and flow resistance coefficient lead to an increase in the domain of stability. A comparison of the linear stability map with the empirical stability map indicates that the non-linear terms do not significantly affect the stability boundary.

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Section: Chaotic Oscillations and Stability Analysis Of Ncl Systemssupporting

confidence: 59%

Stability analysis of a single-phase rectangular Coupled Natural Circulation Loop system employing a Fourier series based 1-D model

Dass,

Gedupudi

2020

Preprint

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“…The bend loss coefficient (K) for the current study is evaluated using the 3K method. Equation (12) provides the expression of the 3K method bend loss correlation which is valid across the laminar, transition and turbulent regime [15]. The values of K 1 ,K ∞ and K d used for elbow bend with R/D h = 1 are 800, 0.14 and 4 respectively and D n represents the hydraulic diameter of the elbow in inches [15].…”

Section: Bend Loss Correlationsmentioning

confidence: 99%

1-D semi-analytical modeling and parametric study of a single phase rectangular Coupled Natural Circulation Loop

Dass

Gedupudi

2019

Chemical Engineering Science

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The study of heat exchangers with both the hot and cold fluid sides driven by buoyancy forces is an area of considerable interest due to their inherent passivity and non-existence of moving parts. The current study aims to study such heat exchange devices employing the basic Coupled Natural Circulation Loop (CNCL) systems. A 1-D Fourier series based semi-analytical model of the basic CNCL system is proposed. A 3-D CFD validation is performed to validate the developed 1-D model. The non-dimensional numbers such as Grashof number, Fourier number, Stanton number and Reynolds number, which determine the system behavior are identified and a detailed parametric study is performed. Both vertical and horizontal CNCL systems are considered along with the parallel and counter flow configurations. The heater-cooler location greatly influences the behavior of CNCL system. The vertical CNCL always exhibits counter flow configuration whereas the horizontal CNCL system may exhibit parallel or counter flow arrangement depending on the heater-cooler location and initial flow conditions.

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“…Those were again mainly caused by the effect of piping loss coefficient due to the model assumptions of the lengths and heights of the injection line and other lines in the DVI loops. In a natural circulation flow, a different height will result a different driving head and a different length means a different piping resistance, and those will affect the resulting mass flowrate along the pipe in the form of flow instability [21].…”

Section: Transient Simulationmentioning

confidence: 99%

Performance Analysis of AP1000 Passive Systems during Direct Vessel Injection (DVI) Line Break

Ekariansyah

Widodo

2016

Atom Indo.

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Generation II Nuclear Power Plants (NPPs) have a design weakness as shown by the Fukushima accident. Therefore, Generation III+ NPPs are developed with focus on improvements of fuel technology and thermal efficiency, standardized design, and the use of passive safety system. One type of Generation III+ NPP is the AP1000 that is a pressurized water reactor (PWR) type that has received the final design acceptance from US-NRC and is already under construction at several sites in China as of 2015. The aim of this study is to investigate the behavior and performance of the passive safety system in the AP1000 and to verify the safety margin during the direct vessel injection (DVI) line break as selected event. This event was simulated using RELAP5/SCDAP/Mod3.4 as a best-estimate code developed for transient simulation of light water reactors during postulated accidents. This event is also described in the AP1000 design control document as one of several postulated accidents simulated using the NOTRUMP code. The results obtained from RELAP5 calculation was then compared with the results of simulations using the NOTRUMP code. The results show relatively good agreements in terms of time sequences and characteristics of some injected flow from the passive safety system. The simulation results show that the break of one of the two available DVI lines can be mitigated by the injected coolant flowing, which is operated effectively by gravity and density difference in the cooling system and does not lead to core uncovery. Despite the substantial effort to obtain an apropriate AP1000 model due to lack of detailed geometrical data, the present model can be used as a platform model for other initiating event considered in the AP1000 accident analysis.

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Computational study of instabilities in a rectangular natural circulation loop using 3D CFD simulation

Cited by 37 publications

References 25 publications

Stability analysis of a single-phase rectangular Coupled Natural Circulation Loop system employing a Fourier series based 1-D model

Stability analysis of a single-phase rectangular Coupled Natural Circulation Loop system employing a Fourier series based 1-D model

1-D semi-analytical modeling and parametric study of a single phase rectangular Coupled Natural Circulation Loop

Performance Analysis of AP1000 Passive Systems during Direct Vessel Injection (DVI) Line Break

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