https://orcid.org/0000-0002-4463-6823
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ABSTRACT
The high thermal efficiency of supercritical water makes it a promising alternative to water cooled reactors. This study employs numerical analysis, utilizing the SST k-ω turbulence model, to investigate the heat transfer performance of supercritical water (SCW) in various tube configurations and fluid flow conditions across Reynolds numbers ranging from 8,000 to 20,000. This research examines how different geometrical parameters, such as the helical direction, number of lobes, and cross-sectional shape, impact the flow physics and heat transfer performance of different spiral tubes. The outcomes specify that increasing the lobed number in the tube improves the heat flux by about 5%–16%. Furthermore, introducing two direction changes in the twisted tube will cause a slight increase (about 20%) on heat transfer enhancement. Finally, the sensitivity analysis of heat flux and Nusselt number to each of the effective parameters in the heat transfer of supercritical water in twisted tubes has been accomplished and the Response Surface Method (RSM) utilizes the central composite design (face-centered) approach. According to the findings of these two studies, it has been established that the Reynolds number of the fluid flow is the most influential parameter in determining the extent of heat transfer. Specifically, it exerts an effectiveness of 26% and 76% on the Nusselt number and heat flux, respectively. Furthermore, the inscribed circle diameter of tube by 8% effectivity and minor axis length by 5% effectivity on heat flux are more effective than others.
GRAPHICAL ABSTRACT
Nomenclature
| Abbreviations | = | |
| HT | = | Heat transfer |
| HTC | = | Heat transfer coefficient |
| HTE | = | Heat transfer enhancement |
| HTD | = | Heat transfer degradation |
| SCW | = | Supercritical water |
| SCWR | = | Supercritical water-cooled Reactor |
| TOT | = | Twisted oval tube |
| TFT | = | Twisted flat tube |
| TTT | = | Tri-lobed twisted tube |
| RANS | = | Reynolds-averaged Navier-Stokes |
| SIMPLE | = | Semi-Implicit Method for Pressure Linked Equations |
| QUICK | = | Quadratic Upwind Interpolation for Convective Kinematics |
| TKE | = | Turbulent kinetic energy |
| Variables | = | |
| = | Velocity vector | |
| = | Fluid density | |
| p | = | Pressure |
| = | Dynamic viscosity | |
| h | = | Enthalpy |
| k | = | Thermal conductivity |
| µt | = | Eddy viscosity coefficients |
| Pk | = | Turbulence production |
| S | = | Strain rate |
| D1 | = | Tube’s inscribed circle diameter |
| D2 | = | Tube’s out-scribed circle diameter |
| r | = | Arc radius |
| a | = | The length of major axis |
| b | = | The length of minor axis |
| P | = | The length of twist pitch |
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Notes on contributors
Amirfarhang Nikkhoo
Amirfarhang Nikkhoo is a dedicated researcher specializing in aerospace and mechanical engineering, with a focus on aerodynamics and computational fluid dynamics (CFD). His passion for research stems from a desire to improve the quality of life through scientific innovation and collaboration with leading experts in the field. Currently pursuing a Master’s degree in Aerospace/Mechanical Engineering at Ferdowsi University of Mashhad, Nikkhoo has demonstrated a keen interest in multidisciplinary topics such as renewable energy, molecular dynamics, and biomechanics. His academic journey includes notable achievements, including a Bachelor’s thesis on simulating drug delivery in blood vessels and a Master’s thesis on optimizing wing geometries for various aerodynamic conditions. Known for his strong analytical skills, attention to detail, and commitment to excellence, Nikkhoo is poised to make significant contributions to the advancement of aerospace and mechanical engineering.
Ali Esmaeili
Ali Esmaeili is an accomplished aerospace engineer with a strong focus on aerodynamics, computational fluid dynamics, and multidisciplinary design optimizations. He earned his Doctorate in Aerospace Engineering from Instituto Superior Tecnico, University of Lisbon, Portugal, in 2018. His research encompasses a wide range of investigations, including computational fluid dynamics, experimental testing, modal and harmonic analysis, fluid-structure interaction, and multidisciplinary design optimizations. His work aims to advance the understanding and application of aerodynamic principles in micro aerial vehicles and energy harvesting technologies.After completing his Ph.D., Esmaeili embarked on a post-doctoral position at Sharif University of Technology before assuming the role of Assistant Professor at Ferdowsi University of Mashhad in 2019. Throughout his career, he has demonstrated a deep commitment to research excellence and innovation in aerospace engineering, making significant contributions to the field through his interdisciplinary approach and dedication to advancing knowledge and technology.
Mahyar Najafian
Mahyar Najafian is a dedicated aerospace engineer who recently earned his Master of Science degree in Aerospace Engineering from Ferdowsi University of Mashhad in 2022. Throughout his academic journey, Najafian demonstrated a keen interest and specialization in fluid dynamics and heat transfer within the aerospace domain.His research efforts have led to the publication of several noteworthy papers in the field, showcasing his contributions to advancing knowledge and understanding in fluid dynamics and heat transfer. Najafian’s work highlights his commitment to exploring and addressing complex challenges within aerospace engineering, particularly in areas related to fluid dynamics and heat transfer phenomena.With his strong academic background, research accomplishments, and specialized expertise, Najafian is poised to make valuable contributions to the aerospace industry, driving innovation and advancements in fluid dynamics and heat transfer technologies.