Download or read book Implications of the Interface Modelling Approach on the Heat Transfer Across Solid Liquid Interfaces and Thin Film Evaporation written by Carlos Gonzalez-Valle and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Dissertation, the governing mechanisms of thermal energy transfer across solid-liquid interfaces and thin-film evaporation are investigated by means of classical molecular dynamics (MD) simulations. In an effort to steer the heat transfer community from heavily empirical techniques into more physically sound methods, significant attention was given to the formulation physics and chemistry informed interface modelling approaches in MD simulations of heat transfer and evaporation. MD simulations were carried out to characterize and analyze the parameters affecting interfacial heat transport, namely, the solid-liquid affinity, the interfacial vibrational compatibility, and the liquid structuring. Understanding and controlling heat transfer and evaporation is fundamental for various applications, such as photothermal therapy and diagnosis, water desalination, additive manufacturing, energy storage and conversion, and thermal management of high-power electronics. For water desalination, electronics cooling, and nanoparticle-mediated thermotherapy, materials featuring good chemical stability, wide band gap, and biological compatibility are necessary. Therefore, inspired by the current technological interests in solid-liquid interfaces, this Dissertation was dedicated to investigate aqueous interfaces of silicon carbide (SiC) and aluminum oxide (alumina). In addition, graphite-water interfaces were used as a reference framework, since this system has been extensively characterized and studied, and several interfacial modelling parameters are available in the literature. The surface wettability was theoretically and numerically characterized for SiC evaluating the effect of different crystallographic orientations and surface terminations. Anysotropy of wettability was found and analytical models based on Mean-Field theory could adequately describe the wetting behavior for compound materials. In addition, the calculations of the interfacial thermal conductance for SiC showed that the most hydrophilic surfaces were not the most conductive, opposing to the conventional notions that related efficient interfacial thermal transport with hydrophilic surfaces. By including additional parameters, such as the interfacial liquid depletion, a reconciliation of the interfacial thermal conductance was observed, indicating that the surface wettability is only one of the mechanisms involved in the thermal transport phenomena. The potential effect of the liquid structuring on the interfacial thermal transport was verified by the calculation of the thermal conductance at the graphite-water interface. The various interface parameters considered produced a wide spectrum of wetting conditions; nonetheless, no direct relationships between wetting parameters such as the contact angle, the work of adhesion, and the binding energy were observed. Similar to the observed for SiC, the liquid density depletion helped to reconcile the calculations of the interfacial conductance for the graphite-water interface. A more complex interfacial model accounting for surface chemistry and electrostatic interactions was developed to analyze the alumina-water interface. The results indicated that wetting and thin-film evaporation are significantly susceptible to interfacial modeling parameters. Moreover, the improper definition of the atomic interactions led to unphysical droplet spreading when using widely accepted modeling parameters for water-alumina interactions. The characterization of interfacial thermal transport for alumina demonstrated the exitance of an interplay between the solid-liquid affinity, the interfacial vibrational compatibility, and the formation of hydrogen bonds. Thin-film evaporation results showed significant variations in the evaporating film thickness and the evaporation mass fluxes with the different interface models, which demonstrated the crucial role of a robust interfacial modelling approach in capturing evaporation in MD simulations.

Download or read book The Surface Wettability Effect on Phase Change written by Marco Marengo and published by Springer Nature. This book was released on 2021-10-30 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Surface Wettability Effect on Phase Change collects high level contributions from internationally recognised scientists in the field. It thoroughly explores surface wettability, with topics spanning from the physics of phase change, physics of nucleation, mesoscale modeling, analysis of phenomena such drop evaporation, boiling, local heat flux at triple line, Leidenfrost, dropwise condensation, heat transfer enhancement, freezing, icing. All the topics are treated by discussing experimental results, mathematical modeling and numerical simulations. In particular, the numerical methods look at direct numerical simulations in the framework of VOF simulations, phase-field simulations and molecular dynamics. An introduction to equilibrium and non-equilibrium thermodynamics of phase change, wetting phenomena, liquid interfaces, numerical simulation of wetting phenomena and phase change is offered for readers who are less familiar in the field. This book will be of interest to researchers, academics, engineers, and postgraduate students working in the area of thermofluids, thermal management, and surface technology.

Download or read book Particles at Fluid Interfaces written by Erica Wanless and published by Frontiers Media SA. This book was released on 2019-05-09 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particles at Fluid Interfaces encompasses the processes and formulations that involve the stabilisation of fluid interfaces by adsorbed particles. The prevalence of these multiphase materials underpins their use in a broad range of industries from personal care and food technology to oil and mineral processing. The stabilisation conferred by the adsorbed particles can be transient as found in froth flotation or long-lived as occurs within Pickering Emulsions. The particles can range in size from nanoparticles to millimetre-sized particles, and cover a spectrum from collapsed proteins, polymeric colloids of controlled size and shape to high dispersity mineral particles.

Download or read book Microscopic Understanding of Two Phase Heat Transfer on Engineered Surfaces written by Arif Rokoni and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase heat transfer is crucial for thermal management of electronic devices, power generation, refrigeration, and water desalination. The use of engineered surfaces can lead to significant improvement in heat dissipation capabilities in pool boiling applications due to the increased nucleation sites, elongated contact lines, increased bubble departure frequency, and microlayer evaporation via enhanced wicking, where the microlayer evaporation is the most dominant mechanism. Hierarchical surfaces demonstrate both significant and limited improvements in heat dissipation over micro-structured surfaces, where the microscopic understanding of wicking and thin-film evaporation is crucial. Nanostructures in hierarchical surfaces can achieve very large heat dissipation rates due to high capillary pressure, where the kinetic resistance across the Knudsen layer of the evaporating interface dictates the evaporation rates. The validity of using classical relations to estimate evaporation rate across the evaporating interface is questioned in recent experimental studies, that requires further investigations using atomic-scale study of evaporation across the interface. In addition, the complex nature of bubble dynamics during pool boiling on flat and engineered surfaces lead to several theoretical and experimental correlations but are substantially different from each other. With the advancement of computational capabilities and artificial intelligence (AI), data-driven deep learning (DL) approach has been heralded as an alternative to the conventional physics-based approach. In the present study, mathematical modeling, wicking, thin-film evaporation experiments, laser interferometry, and AI are utilized to address the unresolved issues mentioned above in two-phase heat transfer on engineered surfaces. First, the significance of micropatterns in wicking enhancement on hierarchical surfaces is demonstrated using microscopic in-house wicking experiments. A mathematical model to estimate the wicking performance for hierarchical surfaces is developed and extended to estimate the enhancement of thin-film evaporation over bare micropillar surfaces. The in-house wicking and thin-film evaporation experimental results are found to be in good agreement with the proposed model. Secondly, to verify the classical relations of evaporation across the liquid-vapor (L-V) interface, non-equilibrium molecular dynamics simulations are performed. The temperature jump and profile calculated across an evaporating L-V interface at various heat fluxes are found in good agreement with the classical theory predictions. To validate the simulation findings from thermodynamics point of view, atomistic interfacial entropy generation rates are calculated and found in qualitative agreement with the predictions from the non-equilibrium thermodynamics. Finally, to better understand the chaotic nature of bubble dynamics in pool boiling, principal component analysis (PCA) is used to extract dominant low dimensional features from pool boiling experimental images of bubble morphologies. The new physical descriptors, dominant frequency, and its amplitude, extracted from the present unsupervised machine learning are qualitatively compared to the bubble count and size extracted from a supervised deep-learning algorithm. This novel reduced-order analysis appears to be highly robust over multiple datasets and heater surfaces.

Download or read book Thermal Energy written by Yatish T. Shah and published by CRC Press. This book was released on 2018-01-12 with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book details sources of thermal energy, methods of capture, and applications. It describes the basics of thermal energy, including measuring thermal energy, laws of thermodynamics that govern its use and transformation, modes of thermal energy, conventional processes, devices and materials, and the methods by which it is transferred. It covers 8 sources of thermal energy: combustion, fusion (solar) fission (nuclear), geothermal, microwave, plasma, waste heat, and thermal energy storage. In each case, the methods of production and capture and its uses are described in detail. It also discusses novel processes and devices used to improve transfer and transformation processes.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multicomponent Interfacial Transport written by Kirill Glavatskiy and published by Springer Science & Business Media. This book was released on 2011-01-18 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thermodynamically consistent description of the transport across interfaces in mixtures has for a long time been an open issue. This research clarifies that the interface between a liquid and a vapor in a mixture is in local equilibrium during evaporation and condensation. It implies that the thermodynamics developed for interfaces by Gibbs can be applied also away from equilibrium, which is typically the case in reality. A description of phase transitions is of great importance for the understanding of both natural and industrial processes. For example, it is relevant for the understanding of the increase of CO2 concentration in the atmosphere, or improvements of efficiency in distillation columns. This excellent work of luminescent scientific novelty has brought this area a significant step forward. The systematic documentation of the approach will facilitate further applications of the theoretical framework to important problems.

Download or read book Advances in Numerical Heat Transfer Volume 2 written by W. Minkowycz and published by Routledge. This book was released on 2018-12-13 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume discusses the advances in numerical heat transfer modeling by applying high-performance computing resources, striking a balance between generic fundamentals, specific fundamentals, generic applications, and specific applications.

Download or read book Fundamentals of Multiphase Heat Transfer and Flow written by Amir Faghri and published by Springer Nature. This book was released on 2019-09-13 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook presents a modern treatment of fundamentals of heat and mass transfer in the context of all types of multiphase flows with possibility of phase-changes among solid, liquid and vapor. It serves equally as a textbook for undergraduate senior and graduate students in a wide variety of engineering disciplines including mechanical engineering, chemical engineering, material science and engineering, nuclear engineering, biomedical engineering, and environmental engineering. Multiphase Heat Transfer and Flow can also be used to teach contemporary and novel applications of heat and mass transfer. Concepts are reinforced with numerous examples and end-of-chapter problems. A solutions manual and PowerPoint presentation are available to instructors. While the book is designed for students, it is also very useful for practicing engineers working in technical areas related to both macro- and micro-scale systems that emphasize multiphase, multicomponent, and non-conventional geometries with coupled heat and mass transfer and phase change, with the possibility of full numerical simulation.

Download or read book Comprehensive Modeling of Thin Film Evaporation in Micropillar Wicks written by Geoffrey Vaartstra and published by . This book was released on 2019 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Information Age, society has become accustomed to continuous, rapid advances in electronics technology. As the power density of these devices increases, heat dissipation threatens to become the limiting factor for growth in the electronics industry. In order to sustain rapid growth, the development of advanced thermal management strategies to efficiently dissipate heat from electronics is imperative. Porous wicks are of great interest in thermal management because they are capable of passively supplying liquid for thin film evaporation, a promising method to reliably dissipate heat in high-performance electronics. While the maximum heat flux that can be reliably sustained (the dryout heat flux) has been well-characterized for many wick configurations, key design information is missing as many previous models cannot determine the distribution of evaporator surface temperature nor temperature at the evaporator's interface with electronic components. Temperature gradients are inherent to the passive capillary pumping mechanism since the shape of the liquid-vapor interface is a function of the local liquid pressure, causing spatial variation of permeability and the heat transfer coefficient (HTC). Accounting for the variation of the liquid-vapor interface to determine the resulting temperature gradients has been a significant modeling challenge. In this thesis, we present a comprehensive modeling framework for thin film evaporation in micropillar wicks that can predict dryout heat flux and local temperature simultaneously. Our numerical approach captures the effect of varying interfacial curvature across the micropillar evaporator to determine the spatial distributions of temperature and heat flux. Heat transfer and capillary flow in the wick are coupled in a computationally efficient manner via incorporation of parametric studies to relate geometry and interface shape to local permeability and HTC. While most previous models only consider uniform thermal loads, our model offers the flexibility to consider arbitrary (non-uniform) thermal loads, making it suitable to guide the design of porous wick evaporators for cooling realistic electronic devices. We present case studies from our model that underscore its capability to guide design with respect to temperature and dryout heat flux. This model predicts notable variations of the HTC (-30%) across the micropillar wick, highlighting the significant effects of interfacial curvature that have not been considered previously. We demonstrate the model's capability to simulate non-uniform thermal loads and show that wick configuration with respect to the input thermal distribution has a significant effect on performance due to the distribution of the HTC and capillary pressure. Further, we are able to quantify the tradeoff associated with enhancing either dryout heat flux or the HTC by optimizing geometry. We offer insights into optimization and further analyze the effects of micropillar geometry on the HTC. Finally, we integrate this model into a fast, compact thermal model (CTM) to make it suitable for thermal/electronics codesign of high-performance devices and demonstrate a thermal simulation of a realistic microprocessor using this CTM. We discuss further uses of our model and describe an experimental platform that could validate our predicted temperature distributions. Lastly, we propose a biporous, area-enhanced wick structure that could push thermal performance to new limits by overcoming the design challenge typically associated with porous wick evaporators.

Download or read book Transport Processes at Fluidic Interfaces written by Dieter Bothe and published by Birkhäuser. This book was released on 2017-07-13 with total page 677 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are several physico-chemical processes that determine the behavior of multiphase fluid systems – e.g., the fluid dynamics in the different phases and the dynamics of the interface(s), mass transport between the fluids, adsorption effects at the interface, and transport of surfactants on the interface – and result in heterogeneous interface properties. In general, these processes are strongly coupled and local properties of the interface play a crucial role. A thorough understanding of the behavior of such complex flow problems must be based on physically sound mathematical models, which especially account for the local processes at the interface. This book presents recent findings on the rigorous derivation and mathematical analysis of such models and on the development of numerical methods for direct numerical simulations. Validation results are based on specifically designed experiments using high-resolution experimental techniques. A special feature of this book is its focus on an interdisciplinary research approach combining Applied Analysis, Numerical Mathematics, Interface Physics and Chemistry, as well as relevant research areas in the Engineering Sciences. The contributions originated from the joint interdisciplinary research projects in the DFG Priority Programme SPP 1506 “Transport Processes at Fluidic Interfaces.”

Download or read book Proceedings of the National Heat Transfer Conference written by and published by . This book was released on 1997 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transport Phenomena in Multiphase Systems written by Amir Faghri and published by Elsevier. This book was released on 2006-05-25 with total page 1060 pages. Available in PDF, EPUB and Kindle. Book excerpt: Engineering students in a wide variety of engineering disciplines from mechanical and chemical to biomedical and materials engineering must master the principles of transport phenomena as an essential tool in analyzing and designing any system or systems wherein momentum, heat and mass are transferred. This textbook was developed to address that need, with a clear presentation of the fundamentals, ample problem sets to reinforce that knowledge, and tangible examples of how this knowledge is put to use in engineering design. Professional engineers, too, will find this book invaluable as reference for everything from heat exchanger design to chemical processing system design and more. * Develops an understanding of the thermal and physical behavior of multiphase systems with phase change, including microscale and porosity, for practical applications in heat transfer, bioengineering, materials science, nuclear engineering, environmental engineering, process engineering, biotechnology and nanotechnology * Brings all three forms of phase change, i.e., liquid vapor, solid liquid and solid vapor, into one volume and describes them from one perspective in the context of fundamental treatment * Presents the generalized integral and differential transport phenomena equations for multi-component multiphase systems in local instance as well as averaging formulations. The molecular approach is also discussed with the connection between microscopic and molecular approaches * Presents basic principles of analyzing transport phenomena in multiphase systems with emphasis on melting, solidification, sublimation, vapor deposition, condensation, evaporation, boiling and two-phase flow heat transfer at the micro and macro levels * Solid/liquid/vapor interfacial phenomena, including the concepts of surface tension, wetting phenomena, disjoining pressure, contact angle, thin films and capillary phenomena, including interfacial balances for mass, species, momentum, and energy for multi-component and multiphase interfaces are discussed * Ample examples and end-of-chapter problems, with Solutions Manual and PowerPoint presentation available to the instructors

Download or read book An Analytical Model for the Heat Transfer to a Capillary Groove written by Sherman Perry Goplen and published by . This book was released on 1977 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 1454 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalog of Research Projects written by United States. Office of Saline Water and published by . This book was released on 1973 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microscale Heat Transfer Fundamentals and Applications written by S. Kakaç and published by Springer Science & Business Media. This book was released on 2006-05-20 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains an archival record of the NATO Advanced Institute on Microscale Heat Transfer – Fundamental and Applications in Biological and Microelectromechanical Systems held in Çesme – Izmir, Turkey, July 18–30, 2004. The ASIs are intended to be high-level teaching activity in scientific and technical areas of current concern. In this volume, the reader may find interesting chapters and various Microscale Heat Transfer Fundamental and Applications. The growing use of electronics, in both military and civilian applications has led to the widespread recognition for need of thermal packaging and management. The use of higher densities and frequencies in microelectronic circuits for computers are increasing day by day. They require effective cooling due to heat generated that is to be dissipated from a relatively low surface area. Hence, the development of efficient cooling techniques for integrated circuit chips is one of the important contemporary applications of Microscale Heat Transfer which has received much attention for cooling of high power electronics and applications in biomechanical and aerospace industries. Microelectromechanical systems are subject of increasing active research in a widening field of discipline. These topics and others are the main themeof this Institute.