Numerical modeling and simulation of particulate fouling on structured heat transfer surfaces using multiphase Eulerian-Lagrangian LES

Numerical modeling and simulation of particulate fouling on structured heat transfer surfaces using multiphase Eulerian-Lagrangian LES
Author: Robert Kasper
Publisher: Cuvillier Verlag
Total Pages: 178
Release: 2021-04-30
Genre: Technology & Engineering
ISBN: 3736964196

Durch die gezielte Strukturierung von wärmeübertragenden Oberflächen, wie beispielsweise durch Dellen oder Rippen, kann die örtliche Turbulenz und damit die thermische Durchmischung gesteigert werden. Dies kann die Effizienz von Wärmeübertragern oder Bauteilkühlsystemen erheblich erhöhen. Derartige Oberflächenstrukturrierungen begünstigen jedoch das Partikelfouling, daher die Ablagerung suspendierter Partikel, wie z.B. Sand, Schlamm oder Korrosionsprodukte. Gegenstand dieser Arbeit ist die Entwicklung eines universellen, numerischen CFD-Verfahrens zur Vorhersage des partikulären Foulings auf strukturierten Oberflächen, speziell Dellenoberflächen. Das entwickelte Verfahren basiert auf einer Kombination des Lagrangian-Particle-Trackings zur Beschreibung der dispersen Phase (Foulingpartikel), sowie räumlich und zeitlich aufgelöster Large-Eddy Simulation für die Berechnung der kontinuierlichen Phasen (Trägerfluid). Dieses Vorgehen ermöglicht nicht nur die Auswertung der infolge der Partikelablagerungen verminderten thermo-hydraulischen Effizienz, sondern auch die Untersuchung der Wechselwirkungen zwischen turbulenten Strömungsstrukturen und dem partikulärem Fouling. Dadurch kann gezeigt werden, dass die Verwendung von sphärischen Dellen als Oberflächenstrukturen nicht nur aus thermo-hydraulischer Sicht die optimale Wahl darstellt, sondern auch eine substantielle Verminderung des Partikelfoulings begünstigt. The application of structured heat transfer surfaces, such as dimples or ribs, increase the local turbulence and thus thermal mixing. This can improve the efficiency of heat exchangers or cooling systems significantly. However, structured surfaces are known to promote particulate fouling, hence the unwanted accumulation and deposition of suspended particles (e.g., silt, sludge or iron oxide). The scope of this work is the development of a universal numerical CFD method for the prediction of particulate fouling, especially on dimpled surfaces. The proposed approach is based on a combination of the Lagrangian point-particle tracking for the description of the disperse phase (fouling particles), and spatially and temporally resolved large-eddy simulations for the calculation of the continuous phase (carrier fluid). This approach allows not only the evaluation of the reduced thermo-hydraulic efficiency due to particle deposition, but also the investigation of the interaction between turbulent flow structures and the particulate fouling. It can be shown that the usage of spherical dimples as surface structures is not only the optimal choice from a thermo-hydraulic point of view, but also favors a substantial reduction of particulate fouling.

Numerical Prediction of Flow, Heat Transfer, Turbulence and Combustion

Numerical Prediction of Flow, Heat Transfer, Turbulence and Combustion
Author: D. Brian Spalding
Publisher: Elsevier
Total Pages: 445
Release: 2015-07-14
Genre: Technology & Engineering
ISBN: 1483160661

Numerical Prediction of Flow, Heat Transfer, Turbulence and Combustion: Selected Works of Professor D. Brian Spalding focuses on the many contributions of Professor Spalding on thermodynamics. This compilation of his works is done to honor the professor on the occasion of his 60th birthday. Relatively, the works contained in this book are selected to highlight the genius of Professor Spalding in this field of interest. The book presents various research on combustion, heat transfer, turbulence, and flows. His thinking on separated flows paved the way for the multi-dimensional modeling of turbulence. Arguments on the universality of the models of turbulence and the problems that are associated with combustion engineering are clarified. The text notes the importance of combustion science as well as the problems associated with it. Mathematical computations are also presented in determining turbulent flows in different environments, including on curved pipes, curved ducts, and rotating ducts. These calculations are presented to further strengthen the claims of Professor Spalding in this discipline. The book is a great find for those who are interested in studying thermodynamics.

Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Concentric Annular Pipe

Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Concentric Annular Pipe
Author: Edris Bagheri
Publisher:
Total Pages: 0
Release: 2021
Genre:
ISBN:

In this thesis, the effects of computational domain size and radius ratio on fully developed turbulent flow and heat transfer in a concentric annular pipe are investigated using direct numerical simulation (DNS). To perform DNS, a new parallel computer code based on the pseudo-spectral method was developed using the FORTRAN 90/95 programing languages and the message passing interface (MPI) libraries. In order to study the effects of computational domain size on the turbulence statistics, twelve test cases of different domain sizes are compared. The effects of radius ratio are investigated through a systematic study based on four radius ratios of a concentric pipe. The characteristics of the velocity and temperature fields are examined at two Reynolds number of Re_(D_h ) =8900$ and 17700. The radius ratio affects the interaction of two boundary layers of the concentric annular pipe and has a significant impact on the turbulent flow structures and dynamics. The characteristics of the flow and temperature fields are investigated in both physical and spectral spaces, which include the analyses of the first- and second-order statistical moments, budget balance of the transport equation of Reynolds stresses, two-point correlation coefficients, and premultiplied spectra of velocity, vorticity, and temperature fluctuations. It is observed that the scales and dynamics of turbulence structures vary with the radius ratio as well as the surface curvature of the concave and convex walls. The characteristic length scales of the turbulence structures are identified through a spectral analysis.

Modelling and Simulation of Turbulent Heat Transfer

Modelling and Simulation of Turbulent Heat Transfer
Author: B. Sundén
Publisher: WIT Press
Total Pages: 361
Release: 2005-02-21
Genre: Science
ISBN: 1853129569

Providing invaluable information for both graduate researchers and R & D engineers in industry and consultancy, this book focuses on the modelling and simulation of fluid flow and thermal transport phenomena in turbulent convective flows. Its overall objective is to present state-of-the-art knowledge in order to predict turbulent heat transfer processes in fundamental and idealized flows as well as in engineering applications. The chapters, which are invited contributions from some of the most prominent scientists in this field, cover a wide range of topics and follow a unified outline and presentation to aid accessibility.

Heat Transfer XIII

Heat Transfer XIII
Author: B. Sundén
Publisher: WIT Press
Total Pages: 549
Release: 2014-07-02
Genre: Technology & Engineering
ISBN: 1845647947

Heat Transfer XIII: Simulation and Experiments in Heat and Mass Transfer contains the proceedings of the thirteenth conference in the well established series on Simulation and Experiments in Heat Transfer and its applications. Advances in computational methods for solving and understanding heat transfer problems continue to be important because heat transfer topics and related phenomena are commonly of a complex nature and different mechanisms like heat conduction, convection, turbulence, thermal radiation and phase change as well as chemical reactions may occur simultaneously. Typically, applications are found in heat exchangers, gas turbine cooling, turbulent combustion and fires, fuel cells, batteries, micro- and mini- channels, electronics cooling, melting and solidification, chemical processing etc. Heat Transfer might be regarded as an established and mature scientific discipline, but it has played a major role in new emerging areas such as sustainable development and reduction of greenhouse gases as well as for micro- and nano- scale structures and bioengineering. Non-linear phenomena other than momentum transfer may occur due to temperature-dependent thermophysical properties. In engineering design and development, reliable and accurate computational methods are requested to replace or complement expensive and time consuming experimental trial an error work. Tremendous advancements have been achieved during recent years due to improved numerical solution methods for non-linear partial differential equations, turbulence modelling advancements and developments of computers and computing algorithms to achieve efficient and rapid simulations. Nevertheless, to further progress in computational methods requires developments in theoretical and predictive procedures – both basic and innovative – and in applied research. Accurate experimental investigations are needed to validate the numerical calculations. Topics covered include: Heat transfer in energy producing devices; Heat transfer enhancements; Heat exchangers; Natural and forced convection and radiation; Multiphase flow heat transfer; Modelling and experiments; Heat recovery; Heat and mass transfer problems; Environmental heat transfer; Experimental and measuring technologies; Thermal convert studies.

Report

Report
Author: United States. National Bureau of Standards
Publisher:
Total Pages: 336
Release: 1968
Genre: Hydraulic engineering
ISBN: