Discussion on the stability of natural circulation loops with supercritical pressure fluids

Debrah, Seth Kofi; Ambrosini, Walter; Chen, Yuzhou

doi:10.1016/j.anucene.2012.10.015

Cited by 34 publications

(2 citation statements)

References 16 publications

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“…On the other hand, Ambrosini [7] employed three different analysis tools, including a system code and in-house linear and transient analysis programs, and analyzed marginal stability boundaries obtained at different channel throttling conditions and orientations. Debrah et al [36] reported that a perturbation amplification factor which is used for a quantitative evaluation of natural circulation loop stability, depends on the dimensionless power-to-flow ratio and the dimensionless heater inlet enthalpy, and also confirmed that decrease in heat transfer coefficient leads to occurrence of unstable behavior, indicating that other closure laws be implemented in the code to enable accurate prediction of heat transfer and flow instability. Debrah et al…”

Section: Figures 4(a)-(c) Respectively Show Schematic Diagram Of a Pamentioning

confidence: 99%

Flow Instability in Parallel Channels with Water at Supercritical Pressure: A Review

Shitsi¹,

Debrah²,

Agbodemegbe³

et al. 2018

WJET

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Research into flow instability at both subcritical and supercritical pressures has attracted attention in recent years because of its potential of occurrence in industrial heat transfer systems. Flow instability has the potential to affect the safety of design and operation of heat transfer equipment. Flow instability is therefore undesirable and should be avoided in the design and operation of industrial equipment. Rahman et al. reviewed studies on supercritical water heat transfer with the aim of providing references for SCWR researchers. It was found out that most of the CFD studies and experimental studies were performed with single tube geometry due to the complexity of parallel channel geometry. Because studies performed with parallel channel geometry could provide detailed information to the design of the SCWR core, they called for more studies in parallel channel geometry at supercritical pressures in the future. In order to help understand how flow instability investigations are carried out and also highlight the need to understand flow instability phenomenon and equip the designers and operators of industrial heat transfer equipment with the needed knowledge on flow instability, this study carried out a review of flow instability in parallel channels with water at supercritical pressures.

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Section: Figures 4(a)-(c) Respectively Show Schematic Diagram Of a Pamentioning

confidence: 99%

Flow Instability in Parallel Channels with Water at Supercritical Pressure: A Review

Shitsi¹,

Debrah²,

Agbodemegbe³

et al. 2018

WJET

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“…The thermal effectiveness of the nanofluids shows that the laminar regions with higher temperatures were favourable for the nanofluid in all volume fractions of MWCNTs. Similarly, Debrah et al [19] conducted stability analysis on the natural circulation loops at supercritical pressure to verify the importance of the heating phenomena and its structure on experimental apparatus and develop a proper methodology related to the loop. Koca et al [20] conducted experiments with Ag/water nanofluid in the mini NCL to analyse the heat power, inclination angles, and effectiveness.…”

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Examining the potential of sigma-thermic heat transfer fluid and its nanofluid in a natural circulation loop through CFD studies

Nagaraju,

Mohammad,

Mendu

et al. 2024

Eng. Res. Express

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This study investigates the impact of hot heat exchanger (HHX) inlet temperature on Sigma-thermic heat transfer fluid (STHF or STF) performance in a natural circulation loop. Various fluids, including STHF and STHF-based nanofluids, with volumetric concentrations ranging from 0.5% to 3%, are employed in the loop. The primary objective is to analyze the thermal performance of the loop under different conditions, focusing on temperature distribution, Nusselt number, friction factor, effectiveness, and mass flow rate. 3D numerical simulations are conducted, and the numerical model is validated against existing literature. The developed model incorporates considerations for viscous dissipation and axial conduction to predict the heat transfer potential of the loop. As the HHX inlet temperature increases, the mass flow rate rises. Notably, STHF/CuO nanofluids exhibit a more substantial enhancement than other nanofluids. At a 1 vol% concentration, the mass flow rate increases by 9.5%, 4%, and 2.7% for STHF/CuO, STHF/Al2O3, and hybrid nanofluids, respectively, compared to pure STHF. The study reveals significant improvements in mass flow rates and heat transfer efficiency with increasing HHX inlet temperatures, especially with STHF/CuO nanofluids. The total entropy generation reduction is notable, with percentages ranging from 2% to 18.5% for various nanofluids compared to pure STHF

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An Overview of the Dynamics of Supercritical Natural Circulation Loops

Srivastava

Sutradhar

Basu

et al. 2019

Energy, Environment, and Sustainability

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Discussion on the stability of natural circulation loops with supercritical pressure fluids

Cited by 34 publications

References 16 publications

Flow Instability in Parallel Channels with Water at Supercritical Pressure: A Review

Flow Instability in Parallel Channels with Water at Supercritical Pressure: A Review

Examining the potential of sigma-thermic heat transfer fluid and its nanofluid in a natural circulation loop through CFD studies

An Overview of the Dynamics of Supercritical Natural Circulation Loops

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