Stability performance of series coupled natural circulation system with different operating procedures

Elton, D.N.; Arunachala, U.C.; Vijayan, P.K.

doi:10.1016/j.ijthermalsci.2022.107693

Cited by 9 publications

(3 citation statements)

References 34 publications

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“…Analytical models have been proposed, including Vijayan's correlation, a simple formulation based on dimensionless numbers applicable to a single NCL [5]. Also numerical models have been used to study NCL behavior under various conditions, such as loop geometry (pipe diameter, length) [6], fluid properties [7], pressure losses [8], power steps or harmonic power excitation [9], Recently, complex loop configurations, such as series-connected [10,11] and parallel-connected loops [12], have also been studied numerically and experimentally. It has been found that even small inner-diameter loops are stable, even in parallel-connected configurations.…”

Section: Introductionmentioning

confidence: 99%

Parallel connected natural circulation loops using different working fluids: experimental results

Bocanegra,

Marchitto,

Misale

2024

J. Phys.: Conf. Ser.

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Natural Circulation Loops (NCLs) are closed-loop systems that transport heat from a source to a heat sink without a pump, relying on free convection of the working fluid. Previous research has focused on the stability and influence of different operative parameters on NCLs. This experimental study investigates the thermo-hydraulic performance of three parallel-connected NCLs with small inner diameters using three different working fluids: deionized water, glycol aqueous solution (50+50% wt), and FC-43 dielectric fluid. This study examines the steady-state behaviour of the NCLs at various heat sink temperatures and heat powers. The results indicate that the common one-dimensional model for a single loop’s steady-state can be applied to this configuration and for all the tested fluids, and a proposed figure of merit can describe the working fluids and predict their steady-state behaviour.

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Section: Introductionmentioning

confidence: 99%

Parallel connected natural circulation loops using different working fluids: experimental results

Bocanegra,

Marchitto,

Misale

2024

J. Phys.: Conf. Ser.

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“…Natural circulation loops (NCLs) are facilities that have an axial length greater than the radial one (Misale and Garibaldi, 2010;Pini, 2017;Cauzzi, 2019), providing important tools for studying the influence of a distributed heat source on the behaviour of natural circulation. In single-phase NCLs, such as the Bhabha single-phase natural circulation loop (Vijayan, 2002), the L2 loop (Misale and Garibaldi, 2010), and the coupled natural circulation loop (CNCL) (Elton et al, 2022), the flow behaviour is mainly affected by density wave instabilities (Welander, 1967). The characteristic velocity of such phenomena significantly depends on local properties such as temperature and pressure losses.…”

Section: Introductionmentioning

confidence: 99%

“…These two competing forces significantly depend on fluid thermal properties which, for a system at constant pressure, are solely related to fluid temperature distribution. Furthermore, the addition of a secondary natural circulation loop further influences the stability of the primary loop, which also significantly depends on the heating configuration and initial conditions (Elton et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

et al. 2023

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In the continuous strive to improve the safety of current-generation and next-generation nuclear power plants, natural circulation can be used to design passive safety systems to remove the decay heat during the shutdown. The Molten Salt Fast Reactor (MSFR) is a peculiar type of Gen-IV nuclear facility, where the fluid fuel is homogeneously mixed with the coolant. This design leads to natural circulation in the presence of an internally distributed heat source during the shutdown. Furthermore, to shield the environment from the highly radioactive fuel, an intermediate loop between the primary and the secondary loops, able to operate in natural circulation, is required. To analyze the natural circulation with a distributed heat source and to study the natural circulation of coupled systems and the influence of the intermediate loop on the behaviour of the primary, Politecnico di Milano designed and built the DYNASTY-eDYNASTY facility. The two facilities are coupled with a double-pipe heat exchanger, which siphons heat from DYNASTY and delivers it to the eDYNASTY loop. This work focuses on modelling the coupled DYNASTY-eDYNASTY natural circulation loops using DYMOLA2023®, an integrated development environment based on the Modelica Object-Oriented a-causal simulation language. The 1D Modelica approach allows for building highly reusable and flexible models easing the design effort on a complex system such as the DYNASTY-eDYNASTY case without the need to rewrite the whole model from scratch. The coupled models were developed starting from the already-validated single DYNASTY model and the double-pipe heat exchanger coupling. The models were tested during the whole development process, studying the influence of the numerical integration algorithm on the simulation behaviour. A preliminary analysis of both the adiabatic and the heat loss models analyzed the effect of the secondary natural circulation loop on the behaviour of the DYNASTY loop. The simulation results showed that the eDYNASTY loop dampens the behaviour of the primary DYNASTY loop. Furthermore, a parametric analysis of the DYNASTY and the eDYNASTY coolers highlighted the influence of the cooling configuration on the facility’s behaviour. Finally, the simulation results identified the most critical aspects of the models in preparation for an experimental comparison.

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Verification and validation of seven turbulence models for a natural circulation loop under transient conditions

Angelo,

Scuro

et al. 2024

Annals of Nuclear Energy

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Stability performance of series coupled natural circulation system with different operating procedures

Cited by 9 publications

References 34 publications

Parallel connected natural circulation loops using different working fluids: experimental results

Parallel connected natural circulation loops using different working fluids: experimental results

1D modelling and preliminary analysis of the coupled DYNASTY–eDYNASTY natural circulation loop

Verification and validation of seven turbulence models for a natural circulation loop under transient conditions

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