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Multiscale Modeling Of Nanostructure Enhanced Two Phase Heat Transfer
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Book Synopsis Multiscale Modeling of Nanostructure-Enhanced Two-Phase Heat Transfer by : Han Hu
Download or read book Multiscale Modeling of Nanostructure-Enhanced Two-Phase Heat Transfer written by Han Hu and published by . This book was released on 2016 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase heat transfer has been widely used in the thermal management of electronics and energy systems. The critical heat flux and heat transfer coefficient of two-phase heat transfer can be significantly enhanced using nanostructures. The objective of current research is to develop the fundamental understandings regarding how nanostructures affect the two-phase heat transfer in the aspects of disjoining pressure, meniscus shape, Kapitza resistance, and evaporative heat transfer coefficient so as to guide nanostructural design for improving heat transfer performance. A multiscale modeling approach is introduced to examine the effects of nanostructures and electrostatic interactions on the equilibrium meniscus shape and disjoining pressure of a thin liquid film on nanostructured surfaces. A general continuum-level model is developed based on the minimization of free energy, the Derjaguin approximation, and the disjoining pressure theory for a flat surface. Molecular dynamics (MD) simulations are performed for water thin films of varying thickness on gold and alumina surfaces with both triangular and square nanostructures of varying depth. Good agreement is obtained between the continuum-level modeling and MD simulations. The results show that the wave amplitude of the meniscus increases with decreasing thin film thickness and increasing nanostructure depth. The electrostatic interactions are shown to enhance the disjoining pressure and make the meniscus more conformal to the nanostructured surfaces. Furthermore, both van der Waals and electrostatic contributions to the disjoining pressure increase with the nanostructure depth and decrease with the film thickness. The effect of nanostructures on Kapitza resistance of water boiling on a gold surface is examined via molecular dynamics simulations. The results show that Kapitza resistance is reduced with increasing nanostructure depth due to the enhanced solid-liquid interactions, and with decreasing nanostructure spacing due to the reduced mismatch in the vibrational properties between the solid and liquid. A closed-form model for the heat transfer coefficient of thin film evaporation on nanostructured surfaces is derived by integrating the evaporation kinetics, disjoining pressure, and Kapitza resistance. Molecular dynamics simulations are performed for water thin films of varying thickness on square gold nanostructures of varying depth. Good agreement is obtained between the continuum-level models and MD simulations. The results also show that there exists a critical film thickness at which the heat transfer coefficient reaches its maximum value. For a film with thicknesses below the critical film thickness, the evaporation resistance dominates the heat transfer, and the heat transfer coefficient increases with film thickness and decreases with nanostructure depth. For a film with thicknesses above the critical film thickness, the conduction resistance dominates the heat transfer, and heat transfer coefficient decreases with film thickness and increases with nanostructure depth. In addition, the critical film thickness increases with the nanostructure depth. The maximum heat transfer coefficient also increases with the nanostructure depth due to the reduction in Kapitza resistance.
Book Synopsis Encyclopedia Of Two-phase Heat Transfer And Flow Iii: Macro And Micro Flow Boiling And Numerical Modeling Fundamentals (A 4-volume Set) by : John R Thome
Download or read book Encyclopedia Of Two-phase Heat Transfer And Flow Iii: Macro And Micro Flow Boiling And Numerical Modeling Fundamentals (A 4-volume Set) written by John R Thome and published by World Scientific. This book was released on 2018-03-13 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Set III of this encyclopedia is a new addition to the previous Sets I and II. It contains 26 invited chapters from international specialists on the topics of numerical modeling of two-phase flows and evaporation, fundamentals of evaporation and condensation in microchannels and macrochannels, development and testing of micro two-phase cooling systems for electronics, and various special topics (surface wetting effects, microfin tubes, two-phase flow vibration across tube bundles). The chapters are written both by renowned university researchers and by well-known engineers from leading corporate research laboratories. Numerous 'must read' chapters cover the fundamentals of research and engineering practice on boiling, condensation and two-phase flows, two-phase heat transfer equipment, electronics cooling systems, case studies and so forth. Set III constitutes a 'must have' reference together with Sets I and II for thermal engineering researchers and practitioners.
Book Synopsis Micro and Nanostructured Surfaces for Enhanced Phase Change Heat Transfer by : Kuang-Han Chu (Ph. D.)
Download or read book Micro and Nanostructured Surfaces for Enhanced Phase Change Heat Transfer written by Kuang-Han Chu (Ph. D.) and published by . This book was released on 2013 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase microchannel heat sinks are of significant interest for thermal management applications, where the latent heat of vaporization offers an efficient method to dissipate large heat fluxes in a compact device. However, a significant challenge for the implementation of microchannel heat sinks is associated with flow instabilities due to insufficient bubble removal, leading to liquid dry-out which severely limits the heat removal efficiency. To address this challenge, we propose to incorporate micro/nanostructures to stabilize and enhance two-phase microchannel flows. Towards this goal, this thesis focuses on fundamental understanding of micro/nanostructures to manipulate liquid and vapor bubble dynamics, and to improve overall microchannel heat transfer performance. We first investigated the role of micro/nanostructure geometry on liquid transport behavior. We designed and fabricated asymmetric nanostructured surfaces where nanopillars are deflected with angles ranging from 7 -52'. Uni-directional liquid spreading was demonstrated where the liquid propagates in a single preferred direction and pins in all others. Through experiments and modeling, we determined that the spreading characteristic is dependent on the degree of nanostructure asymmetry, height-to-spacing ratio of the nanostructures, and intrinsic contact angle. The theory, based on an energy argument, provides excellent agreement with experimental data. This work shows a promising method to manipulate liquid spreading with structured surfaces, which potentially can also be used to manipulate vapor bubble dynamics. We subsequently investigated the effect of micro/nanostructured surface design on vapor bubble dynamics and pool boiling heat transfer. We fabricated micro-, nano-, and hierarchically-structured surfaces with a wide range of well-defined surface roughness factors and measured the heat transfer characteristics. The maximum critical heat flux (CHF) was ~250 W/cm2 with a roughness factor of~-13.3. We also developed a force-balance based model, which shows excellent agreement with the experiments. The results demonstrate the significant effect of surface roughness at capillary length scales on enhancing CHF. This work is an important step towards demonstrating the promising role of surface design for enhanced two-phase heat transfer. Finally, we investigated the heat transfer performance of microstructured surfaces incorporated in microchannel devices with integrated heaters and temperature sensors. We fabricated silicon micropillars with heights of 25 [mu]m, diameters of 5-10 [mu]m and spacings of 5- 10 [mu]m in microchannels of 500 [mu]m x 500 [mu]m. We characterized the performance of the microchannels with a custom closed loop test setup. This thesis provides improved fundamental understanding of the role of micro/nanostructures on liquid spreading and bubble dynamics as well as the practical implementation of such structures in microchannels for enhanced heat transfer. This work serves as an important step towards realizing high flux two-phase microchannel heat sinks for various thermal management applications.
Book Synopsis Multiscale Materials Modeling for Nanomechanics by : Christopher R. Weinberger
Download or read book Multiscale Materials Modeling for Nanomechanics written by Christopher R. Weinberger and published by Springer. This book was released on 2016-08-30 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a unique combination of chapters that together provide a practical introduction to multiscale modeling applied to nanoscale materials mechanics. The goal of this book is to present a balanced treatment of both the theory of the methodology, as well as some practical aspects of conducting the simulations and models. The first half of the book covers some fundamental modeling and simulation techniques ranging from ab-inito methods to the continuum scale. Included in this set of methods are several different concurrent multiscale methods for bridging time and length scales applicable to mechanics at the nanoscale regime. The second half of the book presents a range of case studies from a varied selection of research groups focusing either on a the application of multiscale modeling to a specific nanomaterial, or novel analysis techniques aimed at exploring nanomechanics. Readers are also directed to helpful sites and other resources throughout the book where the simulation codes and methodologies discussed herein can be accessed. Emphasis on the practicality of the detailed techniques is especially felt in the latter half of the book, which is dedicated to specific examples to study nanomechanics and multiscale materials behavior. An instructive avenue for learning how to effectively apply these simulation tools to solve nanomechanics problems is to study previous endeavors. Therefore, each chapter is written by a unique team of experts who have used multiscale materials modeling to solve a practical nanomechanics problem. These chapters provide an extensive picture of the multiscale materials landscape from problem statement through the final results and outlook, providing readers with a roadmap for incorporating these techniques into their own research.
Book Synopsis Heat Exchangers by : Laura Castro Gómez
Download or read book Heat Exchangers written by Laura Castro Gómez and published by BoD – Books on Demand. This book was released on 2022-03-23 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for energy to satisfy the basic needs and services of the population worldwide is increasing as are the economic costs associated with energy production. As such, it is essential to emphasize energy recovery systems to improve heat transfer in thermal processes. Currently, significant research efforts are being conducted to expose criteria and analysis techniques for the design of heat exchange equipment. This book discusses optimization of heat exchangers, heat transfer in novel working fluids, and the experimental and numerical analysis of heat transfer applications.
Book Synopsis Fabrication and Characterization of Nanostructured Surfaces for Enhanced Heat Transfer by : Changho Choi
Download or read book Fabrication and Characterization of Nanostructured Surfaces for Enhanced Heat Transfer written by Changho Choi and published by . This book was released on 2010 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This objective of this study is to investigate the capability of nanostructured surfaces on dissipating heat flux by performing pool boiling and convective flow boiling. The generation of ultra-high heat flux from high performance electric devices has motivated a number of investigations related to advanced heat transfer especially in two-phase boiling performance. It has been reported by a number of researchers that nanostructured surfaces can result in much enhanced boiling performance, compared to the conventional methods by creating desire conditions for heat transfer. In this thesis, various nanostructured surfaces having different morphology were prepared on several engineering relevant substrates and were characterized for their pool boiling performance. Microreactor-assisted-nanomaterial-deposition, MAND [trademark symbol] was used to fabricate a variety of different ZnO nanostructured surfaces by careful adjustment of the processing parameters. ZSM-5 zeolite was synthesized using hydrothermal reaction. ZnO nanostructures in minichannel were also successfully deposited via a flow cell for the application of flow boiling experiment. Scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM) were carried out to characterize the micro- and nanostructures. Contact angle measurement was conducted to evaluate wettability and X-ray Diffraction (XRD) was used to determine the crystalline structures. The most significant enhancement of critical heat flux (CHF) and heat transfer coefficient (HTC) was observed in the flower like ZnO nanostructured surface. We observed pool boiling CHF of 80-82.5 W/cm2 for nanostructured ZnO on Al surfaces versus a CHF of 23.2 W/cm2 on a bare Al surface with a wall superheat reduction of 25-38°C. This new CHF values on nanostructured surfaces corresponds to a boiling heat transfer coefficient as high as ~ 23000 W/m2K. This represents an increase of almost 4X in CHF on nano-textured surfaces, which is the highest enhancement factor reported today.
Book Synopsis Biotemplated Nanostructured Surfaces for Enhanced Two-phase Heat Transfer by : Stephen M. King
Download or read book Biotemplated Nanostructured Surfaces for Enhanced Two-phase Heat Transfer written by Stephen M. King and published by . This book was released on 2012 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Leidenfrost phenomenon is the stable film boiling of a liquid droplet in proximity to a surface whose temperature is much higher than the boiling point of the liquid; caused by rapid vaporization of the droplet before it can come in contact with the surface. This scenario makes conduction through insulating vapor the only means of evaporating the droplet. It is desirable to offset or delay the onset of this occasion of poor heat transfer, the Leidenfrost point, in situations where droplet-to-surface contact is paramount; namely, nuclear reactor safety. Increasing surface hydrophilicity through the implementation of micro, nano, and hierarchical structures has been shown to increase phase-change heat transfer across a surface. In this work, attempts to delay the Leidenfrost phenomenon by tailoring surface wettability with various microstructures conformally coated with novel Tobacco mosaic virus-templated nickel nanostructures are made. Because of a solution based fabrication process, Tobacco mosaic virus nanostructures are potentially more integratable into real-world systems than traditionally fabricated nanostructures. Micropost arrays are patterned in such a way to determine whether the time limiting mechanism in Leidenfrost droplet evaporation is heat transfer or mass transfer dependent. In all, seven patterns (28 samples) with varying thermal conductivities, two-dimensional permeabilities, and heights are: fabricated from SU-8 (photolithography) and silicon (deep reactive-ion etching); tested to determine each surfaces' Leidenfrost point, i.e. the longest droplet evaporation time, through the use of a high-speed camera in concert with a stopwatch; and compared to the performance of flat and nanostructured only surfaces. SU-8 hierarchical posts outperform silicon hierarchical posts, increasing the Leidenfrost point by 175°C (20(mu)m tall) and 250°C (40(mu)m tall) over flat samples, with silicon hierarchies showing only modest improvement,
Book Synopsis Multiscale Modeling of Heat and Mass Transfer Phenomena in Nanofluids by : Felipe Aristizabal
Download or read book Multiscale Modeling of Heat and Mass Transfer Phenomena in Nanofluids written by Felipe Aristizabal and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Heat and mass transfer phenomena in nanofluids are studied using numerical experiments. The main focus of this study is to determine the contribution of nanoparticle Brownian motion-induced micro-convection currents on the effective thermal conductivity and effective mass diffusivity.The mathematical model developed is based on the fluctuating lattice Boltzmann method (fLBM) to simulate nanoparticle Brownian motion, the multiple relaxation time lattice Boltzmann method (MRT-LBM) to provide a description of micro-convection currents, and the finite volume method (FVM) to calculate the evolution of a scalar field (mass or temperature) subject to the effect micro-convection currents. Finally, two averaging methods to calculate effective thermal conductivity and effective mass diffusion coefficient are presented and validated.The results from numerical experiments on heat transfer show that nanoparticle Brownian motion-induced micro-convection currents are not significant enough to justify any notable enhancements in thermal conductivity above the values estimated using classical models for composite materials.In the case of mass transfer, the numerical experiments show that nanoparticle Brownian motion-induced micro-convection currents cause significant enhancements of the effective mass diffusion coefficient. This result is in general agreement with the conclusion drawn by Veilleux and Coulombe (2010, J. Appl. Phys.) using scaling arguments based on the heat and mass transfer Peclet numbers, that Brownian motion has a much larger effect on the mass diffusivity than on the heat diffusivity.The numerical experiments on mass transfer are summarized by a simplified model based on dispersion. The parameters considered in the numerical experiments are: particle size, particle density, fluid viscosity, fluid density and temperature. The simplified model adds two important terms to Maxwell's model: a new dimensionless number N_BM (defined as the ratio of the nanoparticles Brownian self-diffusion coefficient over the molecular diffusion coefficient) and a particle interaction term.Although the simplified model fails to predict the order of magnitude increase in mass diffusivity for Rhodamine 6G in 10 nm Al2O3-water nanofluids (D_eff/D_m = 1.2 compared to the experimental value of 10), the form of the simplified model is used to provide possible explanations for the effective mass diffusivity increase/decrease with nanoparticle volume fraction observed experimentally.This thesis concludes by extending the current analysis to polydisperse nanoparticle suspensions. Numerical experiments on bidisperse suspensions highlight the importance of the interaction term in the simplified model." --
Book Synopsis Advances in Heat Transfer by : Young I. Cho
Download or read book Advances in Heat Transfer written by Young I. Cho and published by Academic Press. This book was released on 2011-11-28 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Transfer fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in journals or texts. The articles, which serve as a broad review for experts in the field, will also be of great interest to non-specialists who need to keep up-to-date with the results of the latest research. This serial is essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, graduate schools or industry. Provides an overview of review articles on topics of current interest Bridges the gap between academic researchers and practitioners in industry A long-running and prestigious series
Book Synopsis Nanofluid Boiling by : Ali Sadaghiani
Download or read book Nanofluid Boiling written by Ali Sadaghiani and published by Academic Press. This book was released on 2024-06-28 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanofluid Boiling presents valuable insights into boiling heat transfer mechanisms, offering state-of-the-art techniques for overcoming obstacles against nanofluid applications. In addition, the book points out emerging industrial applications and guides researchers and engineers in their research and design efforts. In addition, recommendations on future research directions and the design of systems involving nanofluids are presented at the end of each chapter. The book's authors comprehensively cover mechanisms, parametric effects and enhancement techniques in the boiling of nanofluids, providing updated, detailed information about recent developments and findings. Reveals insights into the findings and mechanisms of boiling heat transfer in nanofluids, guiding researchers and engineers in their research and design efforts Focuses on parametric effects such as nanofluid properties (size, concentration, nanoparticle type), preparation methods on heat transfer and critical heat flux mechanisms, bubble dynamics, flow patterns, and pressure drop Presents readers with scaling effects (from macro to microscale) relevant to nanofluid boiling
Book Synopsis Handbook of Thermal Science and Engineering by :
Download or read book Handbook of Thermal Science and Engineering written by and published by Springer. This book was released on 2018-07-31 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Handbook provides researchers, faculty, design engineers in industrial R&D, and practicing engineers in the field concise treatments of advanced and more-recently established topics in thermal science and engineering, with an important emphasis on micro- and nanosystems, not covered in earlier references on applied thermal science, heat transfer or relevant aspects of mechanical/chemical engineering. Major sections address new developments in heat transfer, transport phenomena, single- and multiphase flows with energy transfer, thermal-bioengineering, thermal radiation, combined mode heat transfer, coupled heat and mass transfer, and energy systems. Energy transport at the macro-scale and micro/nano-scales is also included. The internationally recognized team of authors adopt a consistent and systematic approach and writing style, including ample cross reference among topics, offering readers a user-friendly knowledgebase greater than the sum of its parts, perfect for frequent consultation. The Handbook of Thermal Science and Engineering is ideal for academic and professional readers in the traditional and emerging areas of mechanical engineering, chemical engineering, aerospace engineering, bioengineering, electronics fabrication, energy, and manufacturing concerned with the influence thermal phenomena.
Book Synopsis Emerging Nanotechnologies for Renewable Energy by : Waqar Ahmed
Download or read book Emerging Nanotechnologies for Renewable Energy written by Waqar Ahmed and published by Elsevier. This book was released on 2021-02-16 with total page 625 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emerging Nanotechnologies for Renewable Energy offers a detailed overview of the benefits and applications of nanotechnology in the renewable energy sector. The book highlights recent work carried out on the emerging role of nanotechnology in renewable energy applications, ranging from photovoltaics, to battery technology and energy from waste. Written by international authors from both industry and academia, the book covers topics including scaling up from laboratory to industrial scale. It is a valuable resource for students at postgraduate and advanced undergraduate levels, researchers in industry and academia, technology leaders, and policy and decision-makers in the energy and engineering sectors. Offers insights into a wide range of nanoscale technologies for the generation, storage and transfer of energy Shows how nanotechnology is being used to create new, more environmentally friendly energy solutions Assesses the challenges involved in scaling up nanotechnology-based energy solutions to an industrial scale
Book Synopsis Uncertainty Quantification in Multiscale Materials Modeling by : Yan Wang
Download or read book Uncertainty Quantification in Multiscale Materials Modeling written by Yan Wang and published by Woodhead Publishing Limited. This book was released on 2020-03-12 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Uncertainty Quantification in Multiscale Materials Modeling provides a complete overview of uncertainty quantification (UQ) in computational materials science. It provides practical tools and methods along with examples of their application to problems in materials modeling. UQ methods are applied to various multiscale models ranging from the nanoscale to macroscale. This book presents a thorough synthesis of the state-of-the-art in UQ methods for materials modeling, including Bayesian inference, surrogate modeling, random fields, interval analysis, and sensitivity analysis, providing insight into the unique characteristics of models framed at each scale, as well as common issues in modeling across scales.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydrodynamic Aspects of Boiling Heat Transfer by : N. Zuber
Download or read book Hydrodynamic Aspects of Boiling Heat Transfer written by N. Zuber and published by . This book was released on 1959 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Nano/Microscale Heat Transfer by : Zhuomin Zhang
Download or read book Nano/Microscale Heat Transfer written by Zhuomin Zhang and published by McGraw Hill Professional. This book was released on 2007-04-20 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: A THOROUGH EXPLANATION OF THE METHODOLOGIES USED FOR SOLVING HEAT TRANSFER PROBLEMS IN MICRO- AND NANOSYSTEMS. Written by one of the field's pioneers, this highly practical, focused resource integrates the existing body of traditional knowledge with the most recent breakthroughs to offer the reader a solid foundation as well as working technical skills. THE INFORMATION NEEDED TO ACCOUNT FOR THE SIZE EFFECT WHEN DESIGNING AND ANALYZING SYSTEMS AT THE NANOMETER SCALE, WITH COVERAGE OF Statistical Thermodynamics, Quantum Mechanics, Thermal Properties of Molecules, Kinetic Theory, and Micro/Nanofluidics Thermal Transport in Solid Micro/Nanostructures, Electron and Phonon Scattering, Size Effects, Quantum Conductance, Electronic Band Theory, Tunneling, Nonequilibrium Heat Conduction, and Analysis of Solid State Devices Such As Thermoelectric Refrigeration and Optoelectronics Nanoscale Thermal Radiation and Radiative Properties of Nanomaterials, Radiation Temperature and Entropy, Surface Electromagnetic Waves, and Near-Field Radiation for Energy Conversion Devices IN THE NANOWORLD WHERE THE OLD AXIOMS OF THERMAL ANALYSIS MAY NOT APPLY, NANO/MICROSCALE HEAT TRANSFER IS AN ESSENTIAL RESEARCH AND LEARNING SOURCE. Inside: • Statistical Thermodynamics and Kinetic Theory • Thermal Properties of Solids • Thermal Transport in Solids Micro/Nanostructures • Micro/Nanoscale Thermal Radiation • Radiative Properties of Nanomaterials
Book Synopsis Nanoscale Energy Transport and Conversion by : Gang Chen
Download or read book Nanoscale Energy Transport and Conversion written by Gang Chen and published by Oxford University Press. This book was released on 2005-03-03 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a graduate level textbook in nanoscale heat transfer and energy conversion that can also be used as a reference for researchers in the developing field of nanoengineering. It provides a comprehensive overview of microscale heat transfer, focusing on thermal energy storage and transport. Chen broadens the readership by incorporating results from related disciplines, from the point of view of thermal energy storage and transport, and presents related topics on the transport of electrons, phonons, photons, and molecules. This book is part of the MIT-Pappalardo Series in Mechanical Engineering.
