Download or read book Boiling Heat Transfer Enhancement Over a Copper Tube Via Electrolytic and Electrostatic Effect written by 林和靖 and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrostatic Control and Enhancement of Film Boiling Heat Transfer written by Arjang Shahriari and published by . This book was released on 2018 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boiling heat transfer is severely degraded at high surface temperatures due to the formation of a vapor layer at the surface, commonly known as the Leidenfrost effect. Heat transfer is limited to a critical heat flux (CHF); higher heat fluxes lead to surface dryout and temperature excursions. An externally applied electric field in the vapor layer can significantly enhance boiling heat transfer for electrically conducting or polar liquids. In such liquids, the electric field is concentrated in the vapor layer, and promotes liquid-surface contact, which can significantly enhance boiling heat transfer. This dissertation is a fundamental study of the influence of concentrated interfacial electric fields on film boiling heat transfer for liquids with finite electrical conductivity (like water and organic solvents). This dissertation describes experimental, analytical and numerical studies on various aspects of the physics underlying electrostatic suppression of film boiling. This dissertation also quantifies the heat transfer benefits associated with electrostatic suppression of film boiling. This dissertation is divided into five main studies, which analyze different aspects of electrostatic suppression of the Leidenfrost state. The first part of this dissertation (Chapter 2) describes droplet-based experimental investigations on electrostatic suppression of the Leidenfrost state. It is demonstrated that the Leidenfrost state can be suppressed and surface dryout can be prevented using externally applied electric fields (AC or DC). Elimination of the Leidenfrost state increases heat dissipation capacity by more than one order of magnitude. In preliminary experiments, heat removal capacities exceeding 500 W/cm2 are measured for water, which is five times the CHF of water on common engineering surfaces. A multiphysics analytical model is developed to predict the vapor layer thickness in the Leidenfrost state. The second part of this dissertation (Chapter 3) analyzes the fundamental mechanisms underlying electrostatic suppression of Leidenfrost state. It is shown that the interplay of destabilizing and stabilizing forces determines the minimum (threshold) voltage required to suppress the Leidenfrost state. Detailed linear instability analysis is conducted to investigate the growth of electrostatically-induced perturbations on the liquid-vapor interface in the Leidenfrost state, and predict the threshold voltage required for suppression. The third part of this dissertation (Chapter 4) focuses on suppression of the Leidenfrost state on soft, deformable surfaces, like liquids. It is seen that the nature of electrostatic suppression on a deformable liquid substrate is drastically different from that on a solid substrate. This is due to the existence of an electric field inside the substrate and the deformability of the substrate. A multiphysics analytical model is developed to predict the vapor layer thickness on deformable liquids. The fourth part of this dissertation (Chapter 5) includes experimental studies on suppression of film boiling during high temperature quenching of metals. It is shown that an electric field can fundamentally change the boiling patterns, wherein the stable vapor layer (film boiling) is replaced by intermittent wetting of the surface. This fundamental switch in the heat transfer mode significantly accelerates cooling during quenching. An order of magnitude increase in the cooling rate is observed, with the heat transfer seen approaching saturation at higher voltages. An analytical model is developed to extract voltage dependent heat transfer rates from the measured cooling curve. The fifth part of this dissertation (Chapter 6) develops the concept of using acoustic signature tracking to study electrostatic suppression of film boiling. It is shown that acoustic signature tracking can be the basis for objective measurements of the threshold voltage and frequency required for suppression. Acoustic signature tracking can also detect various boiling patterns associated with electrostatically-assisted quenching. With appropriate calibration, this technique can be used to estimate surface temperatures, heat flux and onset of dryout associated with electrically enhanced boiling. In summary, this dissertation has led to seminal contributions in the field of boiling heat transfer, and essentially opened up a new area of study in the field. This work has shown that electric fields can make the CHF limit irrelevant, and reshape the boiling curve. The present work lays the proposed work is evident in the area of quenching, where electrically tunable cooling offers a new foundations for electrically tunable boiling heat transfer with conducting liquids. The impact of the tool to control the microstructure and mechanical properties of metals.
Download or read book High pressure Pool boiling Heat Transfer Enhancement and Mechanism on Engineered Surfaces written by Smreeti Dahariya and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Boiling has received considerable attention in the technology advancement of electronics cooling for high-performance computing applications. Two-phase cooling has an advantage over a single-phase cooling in the high heat removal rate with a small thermal gradient due to the latent heat of vaporization. Many surface modifications have been done in the past including surface roughness, mixed wettability and, porous wick copper play a crucial role in the liquid-vapor phase change heat transfer. However, the mechanisms of high-pressure pool-boiling heat transfer enhancement due to surface modifications has not been well studied or understood. The properties of water, such as the latent heat of vaporization, surface tension, the difference in specific volume of liquid and vapor, decrease at high-pressure. High-pressure pool-boiling heat transfer enhancement is studied fundamentally on various engineered surfaces. The boiling tests are performed at a maximum pressure of 90 psig (620.5 kPa) and then compared to results at 0 psig (0 kPa). The results indicate that the pressure influences the boiling performance through changes in bubble dynamics. The bubble departure diameter, bubble departure frequency, and the active nucleation sites change with pressure. The pool-boiling heat transfer enhancement of a Teflon© coated surface is also experimentally tested, using water as the working fluid. The boiling results are compared with a plain surface at two different pressures, 30 and 45 psig. The maximum heat transfer enhancement is found at the low heat fluxes. At high heat fluxes, a negligible effect is observed in HTC. The primary reasons for the HTC enhancement at low heat fluxes are active nucleation sites at low wall superheat and bubble departure size. The Teflon© coated surface promotes nucleation because of the lower surface energy requirement. The boiling results are also obtained for wick surfaces. The wick surfaces are fabricated using a sintering process. The boiling results are compared with a plain surface. The reasons for enhancements in the pool-boiling performance are primarily due to increased bubble generation, higher bubble release frequency, reduced thermal-hydraulic length modulation, and enhanced thermal conductivity due to the sintered wick layer. The analysis suggests that the Rayleigh-critical wavelength decreases by 4.67 % of varying pressure, which may cause the bubble pinning between the gaps of sintered particles and avoids the bubble coalescence. Changes in the pitch distance indicate that a liquid-vapor phase separation happens at the solid/liquid interface, which impacts the heat-transfer performance significantly. Similarly, the role of the high-pressure over the wicking layer is further analyzed and studied. It is found that the critical flow length, [lambda]u reduces by three times with 200 [mu]m particles. The results suggest that the porous wick layer provides a capillary-assist to liquid flow effect, and delays the surface dry out. The surface modification and the pressure amplify the boiling heat transfer performance. All these reasons may contribute to the CHF, and HTC enhancement in the wicking layer at high-pressure.
Download or read book Nanofluidics written by Efstathios E. (Stathis) Michaelides and published by Springer. This book was released on 2014-05-19 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume offers a comprehensive examination of the subject of heat and mass transfer with nanofluids as well as a critical review of the past and recent research projects in this area. Emphasis is placed on the fundamentals of the transport processes using particle-fluid suspensions, such as nanofluids. The nanofluid research is examined and presented in a holistic way using a great deal of our experience with the subjects of continuum mechanics, statistical thermodynamics, and non-equilibrium thermodynamics of transport processes. Using a thorough database, the experimental, analytical, and numerical advances of recent research in nanofluids are critically examined and connected to past research with medium and fine particles as well as to functional engineering systems. Promising applications and technological issues of heat/mass transfer system design with nanofluids are also discussed. This book also: Provides a deep scientific analysis of nanofluids using classical thermodynamics and statistical thermodynamics to explain and interpret experimental observations Presents the theory and experimental results for both thermodynamic and transport properties Examines all transport properties and transport processes as well as their relationships through the pertinent macroscopic coefficients Combines recent knowledge pertaining to nanofluids with the previous fifty years of research on particulate flows, including research on transient flow and heat transfer of particulate suspensions Conducts an holistic examination of the material from more than 500 archival publications
Download or read book Quantities Units and Symbols in Physical Chemistry written by International Union of Pure and Applied Chemistry. Physical and Biophysical Chemistry Division and published by Royal Society of Chemistry. This book was released on 2007 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared by the IUPAC Physical Chemistry Division this definitive manual, now in its third edition, is designed to improve the exchange of scientific information among the readers in different disciplines and across different nations. This book has been systematically brought up to date and new sections added to reflect the increasing volume of scientific literature and terminology and expressions being used. The Third Edition reflects the experience of the contributors with the previous editions and the comments and feedback have been integrated into this essential resource. This edition has been compiled in machine-readable form and will be available online.
Download or read book Materials with Extreme Wetting Properties written by Majid Hosseini and published by Springer Nature. This book was released on 2021-02-17 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aims at identifying novel advanced materials of extreme wetting properties (MEWP) for practical, industrial applications. The state-of-the art superhdyrophobic, superhdyrophilic, superoleophobic, superoleophilic, and superomniphobic materials, that are MEWP, with respect to their technological and emerging industrial applications are discussed in this book. MEWP offer new perspectives providing numerous potential applications. Hence, these advanced MEWP have the potential to lead to a new generation of products and devices with unique properties and functionalities. Despite the large scientific progress on MEWP there are still some obstacles which have to be solved to make these materials available for real life applications. Recent advances on the production strategies, including methods and materials, of MEWP has shown that the durability and sustainability obstacles can be addressed thus offering the possibility for industrial exploitation. MEWP with wettabilities ranging from superhydrophobicity to superhydrophilicity provide promising avenues for several and important applications, which sometimes are crucial for the humankind. This book also discusses a large variety of other potential applications of MEWP, thus providing new ideas to scientists and engineers for further exploitation of these novel materials. Moreover, the whole spectrum of the recent technological developments, current research progress, future outlook, and the modern trends in the applications of MEWP are discussed in a consistent approach.
Download or read book Extractive Metallurgy of Niobium written by A.K. Suri and published by Routledge. This book was released on 2017-11-13 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth and development witnessed today in modern science, engineering, and technology owes a heavy debt to the rare, refractory, and reactive metals group, of which niobium is a member. Extractive Metallurgy of Niobium presents a vivid account of the metal through its comprehensive discussions of properties and applications, resources and resource processing, chemical processing and compound preparation, metal extraction, and refining and consolidation. Typical flow sheets adopted in some leading niobium-producing countries for the beneficiation of various niobium sources are presented, and various chemical processes for producing pure forms of niobium intermediates such as chloride, fluoride, and oxide are discussed. The book also explains how to liberate the metal from its intermediates and describes the physico-chemical principles involved. It is an excellent reference for chemical metallurgists, hydrometallurgists, extraction and process metallurgists, and minerals processors. It is also valuable to a wide variety of scientists, engineers, technologists, and students interested in the topic.
Download or read book Thermal Management of Electronic Systems II written by E. Beyne and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the second time, the Eurotherm Committee has chosen Thermal Managment of Electronic Systems as the subject for its 45th Seminar, held at IMEC in Leuven, Belgium, from 20 to 22 September 1995. After the successfui first edition of this seminar in Delft, June 14-16, 1993, it was decided to repeat this event on a two year basis. This volume constitutes the edited proceedings of the Seminar. Thermal management of electronic systems is gaining importance. Whereas a few years ago papers on this subject where mainly devoted to applications in high end markets, such as mainframes and telecommunication switching equipment, we see a growing importance in the "lower" end applications. This may be understood from the growing impact of electronics on every day life, from car electronics, GSM phones, personal computers to electronic games. These applications add new requirements to the thermal design. The thermal problem and the applicable cooling strategies are quite different from those in high end products. In this seminar the latest developments in many of the different aspects of the thermal design of electronic systems were discussed. Particular attention was given to thermal modelling, experimental characterisation and the impact of thermal design on the reliability of electronic systems.
Download or read book Chemical Process Design and Integration written by Robin Smith and published by John Wiley & Sons. This book was released on 2016-08-02 with total page 923 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a highly regarded author with industrial and academic experience, this new edition of an established bestselling book provides practical guidance for students, researchers, and those in chemical engineering. The book includes a new section on sustainable energy, with sections on carbon capture and sequestration, as a result of increasing environmental awareness; and a companion website that includes problems, worked solutions, and Excel spreadsheets to enable students to carry out complex calculations.
Download or read book Polymer Electrolyte Fuel Cell Durability written by Felix N. Büchi and published by Springer Science & Business Media. This book was released on 2009-02-08 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a significant number of R&D projects, performed mostly after 2000, devoted to the understanding and prevention of performance degradation processes in polymer electrolyte fuel cells (PEFCs). The extent and severity of performance degradation processes in PEFCs were recognized rather gradually. Indeed, the recognition overlapped with a significant number of industrial dem- strations of fuel cell powered vehicles, which would suggest a degree of technology maturity beyond the resaolution of fundamental failure mechanisms. An intriguing question, therefore, is why has there been this apparent delay in addressing fun- mental performance stability requirements. The apparent answer is that testing of the power system under fully realistic operation conditions was one prerequisite for revealing the nature and extent of some key modes of PEFC stack failure. Such modes of failure were not exposed to a similar degree, or not at all, in earlier tests of PEFC stacks which were not performed under fully relevant conditions, parti- larly such tests which did not include multiple on–off and/or high power–low power cycles typical for transportation and mobile power applications of PEFCs. Long-term testing of PEFCs reported in the early 1990s by both Los Alamos National Laboratory and Ballard Power was performed under conditions of c- stant cell voltage, typically near the maximum power point of the PEFC.
Download or read book CRC Handbook of Metal Etchants written by Perrin Walker and published by CRC Press. This book was released on 1990-12-11 with total page 1434 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication presents cleaning and etching solutions, their applications, and results on inorganic materials. It is a comprehensive collection of etching and cleaning solutions in a single source. Chemical formulas are presented in one of three standard formats - general, electrolytic or ionized gas formats - to insure inclusion of all necessary operational data as shown in references that accompany each numbered formula. The book describes other applications of specific solutions, including their use on other metals or metallic compounds. Physical properties, association of natural and man-made minerals, and materials are shown in relationship to crystal structure, special processing techniques and solid state devices and assemblies fabricated. This publication also presents a number of organic materials which are widely used in handling and general processing...waxes, plastics, and lacquers for example. It is useful to individuals involved in study, development, and processing of metals and metallic compounds. It is invaluable for readers from the college level to industrial R & D and full-scale device fabrication, testing and sales. Scientific disciplines, work areas and individuals with great interest include: chemistry, physics, metallurgy, geology, solid state, ceramic and glass, research libraries, individuals dealing with chemical processing of inorganic materials, societies and schools.
Download or read book Introduction to Surface Engineering written by P. A. Dearnley and published by Cambridge University Press. This book was released on 2017-01-16 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: This highly illustrated reference work covers the three principal types of surface technologies that best protect engineering devices and products: diffusion technologies, deposition technologies, and other less commonly acknowledged surface engineering (SE) techniques. Various applications are noted throughout the text and additionally whole chapters are devoted to specific SE applications across the automotive, gas turbine engine (GTE), metal machining, and biomedical implant sectors. Along with the benefits of SE, this volume also critically examines SE's limitations. Materials degradation pathways - those which can and those which cannot be mitigated by SE - are rigorously explained. Written from a scientific, materials engineering perspective, this concise text is supported by high-quality images and photo-micrographs which show how surfaces can be engineered to overcome the limits of conventionally produced materials, even in complex or hostile operating environments. This book is a useful resource for undergraduate and postgraduate students as well as professional engineers.
Download or read book Physical and Chemical Properties of Carbon Nanotubes written by Satoru Suzuki and published by . This book was released on 2013 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are rolled up graphene sheets with a quasi-one-dimensional structure of nanometer-scale diameter. In these last twenty years, carbon nanotubes have attracted much attention from physicists, chemists, material scientists, and electronic device engineers because of their excellent structural, electronic, optical, chemical and mechanical properties. Carbon nanotube research, especially that aiming at industrial applications, is becoming more important. This book covers recent research topics regarding the physical, structural, chemical and electric properties on carbon nanotubes. All chapters were written by researchers who are active on the front lines. The chapters in this book will be helpful to many students, engineers and researchers working in the field of carbon nanotubes.
Download or read book Fluid Bed Technology in Materials Processing written by C. K. Gupta and published by CRC Press. This book was released on 1998-12-28 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid Bed Technology in Materials Processing comprehensively covers the various aspects of fluidization engineering and presents an elaborate examination of the applications in a multitude of materials processing techniques. This singular resource discusses: All the basic aspects of fluidization essential to understand and learn about various techniques The range of industrial applications Several examples in extraction and process metallurgy Fluidization in nuclear engineering and nuclear fuel cycle with numerous examples Innovative techniques and several advanced concepts of fluidization engineering, including use and applications in materials processing as well as environmental and bio-engineering Pros and cons of various fluidization equipment and specialty of their applications, including several examples Design aspects and modeling Topics related to distributors effects and flow regimes A separate chapter outlines the importance of fluidization engineering in high temperature processing, including an analysis of the fundamental concepts and applications of high temperature fluidized bed furnaces for several advanced materials processing techniques. Presenting information usually not available in a single source, Fluid Bed Technology in Materials Processing serves Fluidization engineers Practicing engineers in process metallurgy, mineral engineering, and chemical metallurgy Researchers in the field of chemical, metallurgical, nuclear, biological, environmental engineering Energy engineering professionals High temperature scientists and engineers Students and professionals who adopt modeling of fluidization in their venture for design and scale up
Download or read book Hot Embossing written by Matthias Worgull and published by William Andrew. This book was released on 2009-09-28 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an overview of replication technology for micro- and nanostructures, focusing on the techniques and technology of hot embossing, a scaleable and multi-purpose technology for the manufacture of devices such as BioMEMS and microfluidic devices which are expected to revolutionize a wide range of medical and industrial processes over the coming decade.The hot embossing process for replicating microstructures was developed by the Forschungszentrum Karlsruhe (Karlsruhe Institute of Technology) where the author is head of the Nanoreplication Group. Worgull fills a gap in existing information by fully detailing the technology and techniques of hot embossing. He also covers nanoimprinting, a process related to hot embossing, with examples of actual research topics and new applications in nanoreplication. A practical and theoretical guide to selecting the materials, machinery and processes involved in microreplication using hot embossing techniques Compares different replication processes such as: micro injection molding, micro thermoforming, micro hot embossing, and nanoimprinting Details commercially available hot embossing machinery and components like tools and mold inserts
Download or read book ACS Style Guide written by Anne M. Coghill and published by American Chemical Society. This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the time since the second edition of The ACS Style Guide was published, the rapid growth of electronic communication has dramatically changed the scientific, technical, and medical (STM) publication world. This dynamic mode of dissemination is enabling scientists, engineers, and medicalpractitioners all over the world to obtain and transmit information quickly and easily. An essential constant in this changing environment is the requirement that information remain accurate, clear, unambiguous, and ethically sound.This extensive revision of The ACS Style Guide thoroughly examines electronic tools now available to assist STM writers in preparing manuscripts and communicating with publishers. Valuable updates include discussions of markup languages, citation of electronic sources, online submission ofmanuscripts, and preparation of figures, tables, and structures. In keeping current with the changing environment, this edition also contains references to many resources on the internet.With this wealth of new information, The ACS Style Guide's Third Edition continues its long tradition of providing invaluable insight on ethics in scientific communication, the editorial process, copyright, conventions in chemistry, grammar, punctuation, spelling, and writing style for any STMauthor, reviewer, or editor. The Third Edition is the definitive source for all information needed to write, review, submit, and edit scholarly and scientific manuscripts.
Download or read book Graphene Nanoelectronics written by Hassan Raza and published by Springer Science & Business Media. This book was released on 2012-03-05 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphene is a perfectly two-dimensional single-atom thin membrane with zero bandgap. It has attracted huge attention due to its linear dispersion around the Dirac point, excellent transport properties, novel magnetic characteristics, and low spin-orbit coupling. Graphene and its nanostructures may have potential applications in spintronics, photonics, plasmonics and electronics. This book brings together a team of experts to provide an overview of the most advanced topics in theory, experiments, spectroscopy and applications of graphene and its nanostructures. It covers the state-of-the-art in tutorial-like and review-like manner to make the book useful not only to experts, but also newcomers and graduate students.
