Numerical Simulations of Steady Low-Reynolds-number Flows and Enhanced Heat Transfer in Wavy Plate-fin Passages PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Extended or finned surfaces are widely used in compact heat exchangers to reduce the thermal resistance of air- or gas-side flows. Besides increasing the effective heat transfer surface area, geometrically modified finned surfaces also improve the heat transfer coefficient by altering the flow field. Wavy plate-fin surfaces have such properties and promote relatively high thermal-hydraulic performance. They are also attractive for their simplicity of manufacture and ease of use in compact heat exchangers. The current study numerically investigates the fluid flow and enhanced convection heat transfer in two-dimensional and three-dimensional wavy plate-fin passages with sinusoidal wall corrugations in the low Reynolds number regime. Constant property, periodically fully developed, and laminar or low Reynolds number forced convection are considered. The governing equations of continuity, momentum, and energy are solved computationally using finite-volume techniques. The solution procedure is based on the SIMPLE algorithm and a non-orthogonal, non-uniform grid. The influences of fin geometry (fin spacing, fin height, fin amplitude and fin length) on the enhanced heat transfer and fluid flow behaviors are investigated. The simulation results for the velocity and temperature distributions, isothermal Fanning friction f, and Colburn factor j are presented and discussed. The complex flow patterns in the wavy-fin channel are characterized by re-circulating and/or helical swirl flows with periodic flow separation and reattachment. Two flow regimes can be classified based on these results, namely, (1) low-Re streamline-flow regime where viscous forces dominate, and (2) high-Re swirl-flow regime characterized by flow recirculation and/or helical vortices. Heat transfer enhancement is observed in the swirl flow regime along with an increased pressure drop penalty, as a consequence of the periodic thermal boundary-layer thinning, strong flow mixing, and periodic generation and dissipation of vortices or re-circulating cells. In the streamline-flow regime, the flow and heat transfer behavior are similar to that in straight flow channel, though an enhanced performance is obtained. Also, results of flow visualization experiment for a two-dimensional wavy flow channel are shown to agree well with the numerical results. Finally, the computational methodology is extended to illustrate the flow behaviors in out-of-phase wavy flow passages.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Extended or finned surfaces are widely used in compact heat exchangers to reduce the thermal resistance of air- or gas-side flows. Besides increasing the effective heat transfer surface area, geometrically modified finned surfaces also improve the heat transfer coefficient by altering the flow field. Wavy plate-fin surfaces have such properties and promote relatively high thermal-hydraulic performance. They are also attractive for their simplicity of manufacture and ease of use in compact heat exchangers. The current study numerically investigates the fluid flow and enhanced convection heat transfer in two-dimensional and three-dimensional wavy plate-fin passages with sinusoidal wall corrugations in the low Reynolds number regime. Constant property, periodically fully developed, and laminar or low Reynolds number forced convection are considered. The governing equations of continuity, momentum, and energy are solved computationally using finite-volume techniques. The solution procedure is based on the SIMPLE algorithm and a non-orthogonal, non-uniform grid. The influences of fin geometry (fin spacing, fin height, fin amplitude and fin length) on the enhanced heat transfer and fluid flow behaviors are investigated. The simulation results for the velocity and temperature distributions, isothermal Fanning friction f, and Colburn factor j are presented and discussed. The complex flow patterns in the wavy-fin channel are characterized by re-circulating and/or helical swirl flows with periodic flow separation and reattachment. Two flow regimes can be classified based on these results, namely, (1) low-Re streamline-flow regime where viscous forces dominate, and (2) high-Re swirl-flow regime characterized by flow recirculation and/or helical vortices. Heat transfer enhancement is observed in the swirl flow regime along with an increased pressure drop penalty, as a consequence of the periodic thermal boundary-layer thinning, strong flow mixing, and periodic generation and dissipation of vortices or re-circulating cells. In the streamline-flow regime, the flow and heat transfer behavior are similar to that in straight flow channel, though an enhanced performance is obtained. Also, results of flow visualization experiment for a two-dimensional wavy flow channel are shown to agree well with the numerical results. Finally, the computational methodology is extended to illustrate the flow behaviors in out-of-phase wavy flow passages.
Author: Aroon Shenoy Publisher: CRC Press ISBN: 1315350653 Category : Science Languages : en Pages : 288
Book Description
Convective Flow and Heat Transfer from Wavy Surfaces: Viscous Fluids, Porous Media, and Nanofluids addresses the wavy irregular surfaces in heat transfer devices. Fluid flow and heat transfer studies from wavy surfaces have received attention, since they add complexity and require special mathematical techniques. This book considers the flow and heat transfer characteristics from wavy surfaces, providing an understanding of convective behavioral changes.
Author: Bar-cohen Avram Publisher: World Scientific ISBN: 9813239689 Category : Technology & Engineering Languages : en Pages : 904
Book Description
Thermal and mechanical packaging — the enabling technologies for the physical implementation of electronic systems — are responsible for much of the progress in miniaturization, reliability, and functional density achieved by electronic, microelectronic, and nanoelectronic products during the past 50 years. The inherent inefficiency of electronic devices and their sensitivity to heat have placed thermal packaging on the critical path of nearly every product development effort in traditional, as well as emerging, electronic product categories.Successful thermal packaging is the key differentiator in electronic products, as diverse as supercomputers and cell phones, and continues to be of pivotal importance in the refinement of traditional products and in the development of products for new applications. The Encyclopedia of Thermal Packaging, compiled in four multi-volume sets (Set 1: Thermal Packaging Techniques, Set 2: Thermal Packaging Tools, Set 3: Thermal Packaging Applications, and Set 4: Thermal Packaging Configurations) provides a comprehensive, one-stop treatment of the techniques, tools, applications, and configurations of electronic thermal packaging. Each of the author-written volumes presents the accumulated wisdom and shared perspectives of a few luminaries in the thermal management of electronics.The four sets in the Encyclopedia of Thermal Packaging will provide the novice and student with a complete reference for a quick ascent on the thermal packaging 'learning curve,' the practitioner with a validated set of techniques and tools to face every challenge, and researchers with a clear definition of the state-of-the-art and emerging needs to guide their future efforts. This encyclopedia will, thus, be of great interest to packaging engineers, electronic product development engineers, and product managers, as well as to researchers in thermal management of electronic and photonic components and systems, and most beneficial to undergraduate and graduate students studying mechanical, electrical, and electronic engineering.Set 3: Thermal Packaging ApplicationsThe third set in the Encyclopedia includes two volumes in the planned focus on Thermal Packaging Applications and a single volume on the use of Phase Change Materials (PCM), a most important Thermal Management Technique, not previously addressed in the Encyclopedia. Set 3 opens with Heat Transfer in Avionic Equipment, authored by Dr Boris Abramzon, offering a comprehensive, in-depth treatment of compact heat exchangers and cold plates for avionics cooling, as well as discussion on recent developments in these heat transfer units that are widely used in the thermal control of military and civilian airborne electronics. Along with a detailed presentation of the relevant thermofluid physics and governing equations, and the supporting mathematical design and optimization techniques, the book offers a practical guide for thermal engineers designing avionics cooling equipment, based on the author's 20+ years of experience as a thermal analyst and a practical design engineer for Avionics and related systems.The Set continues with Thermal Management of RF Systems, which addresses sequentially the history, present practice, and future thermal management strategies for electronically-steered RF systems, in the context of the RF operational requirements, as well as device-, module-, and system-level electronic, thermal, and mechanical considerations. This unique text was written by 3 authors, Dr John D Albrecht, Mr David H Altman, Dr Joseph J Maurer, with extensive US Department of Defense and aerospace industry experience in the design, development, and fielding of RF systems. Their combined efforts have resulted in a text, which is well-grounded in the relevant past, present, and future RF systems and technologies. Thus, this volume will provide the designers of advanced radars and other electronic RF systems with the tools and the knowledge to address the thermal management challenges of today's technologies, as well as of advanced technologies, such as wide bandgap semiconductors, heterogeneously integrated devices, and 3D chipsets and stacks.The third volume in Set 3, Phase Change Materials for Thermal Management of Electronic Components, co-authored by Prof Gennady Ziskind and Dr Yoram Kozak, provides a detailed description of the numerical methods used in PCM analysis and a detailed explanation of the processes that accompany and characterize solid-liquid phase-change in popular basic and advanced geometries. These provide a foundation for an in-depth exploration of specific electronics thermal management applications of Phase Change Materials. This volume is anchored in the unique PCM knowledge and experience of the senior author and placed in the context of the extensive solid-liquid phase-change literature in such diverse fields as material science, mathematical modeling, experimental and numerical methods, and thermofluid science and engineering.
Author: Publisher: ISBN: Category : Engineering Languages : en Pages : 2264
Book Description
Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.
Author: Satish Kandlikar Publisher: Elsevier ISBN: 9780080445274 Category : Science Languages : en Pages : 492
Book Description
&Quot;This book explores flow through passages with hydraulic diameters from about 1 [mu]m to 3 mm, covering the range of minichannels and microchannels. Design equations along with solved examples and practice problems are also included to serve the needs of practicing engineers and students in a graduate course."--BOOK JACKET.
Author: J.E. Hesselgreaves Publisher: Elsevier ISBN: 0080529542 Category : Technology & Engineering Languages : en Pages : 417
Book Description
This book presents the ideas and industrial concepts in compact heat exchanger technology that have been developed in the last 10 years or so. Historically, the development and application of compact heat exchangers and their surfaces has taken place in a piecemeal fashion in a number of rather unrelated areas, principally those of the automotive and prime mover, aerospace, cryogenic and refrigeration sectors. Much detailed technology, familiar in one sector, progressed only slowly over the boundary into another sector. This compartmentalisation was a feature both of the user industries themselves, and also of the supplier, or manufacturing industries. These barriers are now breaking down, with valuable cross-fertilisation taking place. One of the industrial sectors that is waking up to the challenges of compact heat exchangers is that broadly defined as the process sector. If there is a bias in the book, it is towards this sector. Here, in many cases, the technical challenges are severe, since high pressures and temperatures are often involved, and working fluids can be corrosive, reactive or toxic. The opportunities, however, are correspondingly high, since compacts can offer a combination of lower capital or installed cost, lower temperature differences (and hence running costs), and lower inventory. In some cases they give the opportunity for a radical re-think of the process design, by the introduction of process intensification (PI) concepts such as combining process elements in one unit. An example of this is reaction and heat exchange, which offers, among other advantages, significantly lower by-product production.To stimulate future research, the author includes coverage of hitherto neglected approaches, such as that of the Second Law (of Thermodynamics), pioneered by Bejan and co- workers. The justification for this is that there is increasing interest in life-cycle and sustainable approaches to industrial activity as a whole, often involving exergy (Second Law) analysis. Heat exchangers, being fundamental components of energy and process systems, are both savers and spenders of exergy, according to interpretation.
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Author: Satish Kandlikar
Author: J.E. Hesselgreaves