A Theoretical Analysis of Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion

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ISBN 13 :
Total Pages : 54 pages
Book Rating : 4.:/5 (798 download)

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Book Synopsis A Theoretical Analysis of Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion by : Mark Miner

Download or read book A Theoretical Analysis of Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion written by Mark Miner and published by . This book was released on 2011 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microchannel heat sinks can possess heat transfer characteristics unavailable in conventional heat exchangers; such sinks offer compact solutions to otherwise intractable thermal management problems, notably in small-scale electronics cooling. Flow boiling in microchannels allows a very high heat transfer rate, but is bounded by the critical heat flux (CHF). This thesis presents a theoretical-numerical study of a method to improve the heat rejection capability of a microchannel heat sink via expansion of the channel cross-section along the flow direction. The thermodynamic quality of the refrigerant increases during flow boiling, decreasing the density of the bulk coolant as it flows. This may effect pressure fluctuations in the channels, leading to nonuniform heat transfer and local dryout in regions exceeding CHF. This undesirable phenomenon is counteracted by permitting the cross-section of the microchannel to increase along the direction of flow, allowing more volume for the vapor. Governing equations are derived from a control-volume analysis of a single heated rectangular microchannel; the cross-section is allowed to expand in width and height. The resulting differential equations are solved numerically for a variety of channel expansion profiles and numbers of channels. The refrigerant is R-134a and channel parameters are based on a physical test bed in a related experiment. Significant improvement in CHF is possible with moderate area expansion. Minimal additional manufacturing costs could yield major gains in the utility of microchannel heat sinks. An optimum expansion rate occurred in certain cases, and alterations in the channel width are, in general, more effective at improving CHF than alterations in the channel height. Modest expansion in height enables small width expansions to be very effective.

Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion

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ISBN 13 :
Total Pages : 134 pages
Book Rating : 4.:/5 (861 download)

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Book Synopsis Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion by : Mark Miner

Download or read book Microchannel Flow Boiling Enhancement Via Cross-sectional Expansion written by Mark Miner and published by . This book was released on 2013 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heat transfer enhancements available from expanding the cross-section of a boiling microchannel are explored analytically and experimentally. Evaluation of the literature on critical heat flux in flow boiling and associated pressure drop behavior is presented with predictive critical heat flux (CHF) and pressure drop correlations. An optimum channel configuration allowing maximum CHF while reducing pressure drop is sought. A perturbation of the channel diameter is employed to examine CHF and pressure drop relationships from the literature with the aim of identifying those adequately general and suitable for use in a scenario with an expanding channel. Several CHF criteria are identified which predict an optimizable channel expansion, though many do not. Pressure drop relationships admit improvement with expansion, and no optimum presents itself. The relevant physical phenomena surrounding flow boiling pressure drop are considered, and a balance of dimensionless numbers is presented that may be of qualitative use. The design, fabrication, inspection, and experimental evaluation of four copper microchannel arrays of different channel expansion rates with R-134a refrigerant is presented. Optimum rates of expansion which maximize the critical heat flux are considered at multiple flow rates, and experimental results are presented demonstrating optima. The effect of expansion on the boiling number is considered, and experiments demonstrate that expansion produces a notable increase in the boiling number in the region explored, though no optima are observed. Significant decrease in the pressure drop across the evaporator is observed with the expanding channels, and no optima appear. Discussion of the significance of this finding is presented, along with possible avenues for future work.

Heat Transfer and Fluid Flow in Minichannels and Microchannels

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Publisher : Elsevier
ISBN 13 : 9780080445274
Total Pages : 492 pages
Book Rating : 4.4/5 (452 download)

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Book Synopsis Heat Transfer and Fluid Flow in Minichannels and Microchannels by : Satish Kandlikar

Download or read book Heat Transfer and Fluid Flow in Minichannels and Microchannels written by Satish Kandlikar and published by Elsevier. This book was released on 2006 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: &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.

Flow Boiling in Expanding Microchannels

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Publisher : Springer
ISBN 13 : 3319550322
Total Pages : 89 pages
Book Rating : 4.3/5 (195 download)

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Book Synopsis Flow Boiling in Expanding Microchannels by : Tamanna Alam

Download or read book Flow Boiling in Expanding Microchannels written by Tamanna Alam and published by Springer. This book was released on 2017-05-24 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.

Laminar Flow Forced Convection in Ducts

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Publisher : Academic Press
ISBN 13 : 1483191303
Total Pages : 492 pages
Book Rating : 4.4/5 (831 download)

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Book Synopsis Laminar Flow Forced Convection in Ducts by : R. K. Shah

Download or read book Laminar Flow Forced Convection in Ducts written by R. K. Shah and published by Academic Press. This book was released on 2014-06-28 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar Flow Forced Convection in Ducts is a sourcebook for compact heat exchanger analytical data. This book describes the analytical solutions for laminar fluid flow and forced convection heat transfer in circular and noncircular pipes, including applicable differential equations and boundary conditions involving velocity and temperature problems of fluid flow. The book also discusses fluid flow—how much power is required to pump fluids through the heat exchanger, as well as the heat transfer—the determination of q" distribution, and the temperature of fluid and walls. The text also analyzes the coolant or heat transfer fluid flows in a nuclear power reactor composed of a bundle of circular section fuel rods located inside a round tube. R.A. Axford addresses fluid flow and heat transfers results for the rod bundle geometry in "Heat Transfer in Rod Bundles." The book also provides an overview and guidelines that can be used for the designer and the applied mathematician. This book is suitable for engineers working in electronics, aerospace, instrumentation, and biomechanics that use cooling or heating exchanges or solar collection systems.

Handbook of Thermal Science and Engineering

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Publisher : Springer
ISBN 13 : 9783319266947
Total Pages : 0 pages
Book Rating : 4.2/5 (669 download)

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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.

Flow Boiling Heat Transfer Over Open Microchannels with Tapered Manifold

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Publisher :
ISBN 13 :
Total Pages : 378 pages
Book Rating : 4.:/5 (948 download)

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Book Synopsis Flow Boiling Heat Transfer Over Open Microchannels with Tapered Manifold by : Ankit Kalani

Download or read book Flow Boiling Heat Transfer Over Open Microchannels with Tapered Manifold written by Ankit Kalani and published by . This book was released on 2016 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Boiling can provide several orders of magnitude higher performance than a traditional air cooled system in electronics cooling application. It can dissipate large quantities of heat while maintaining a low surface temperature to fluid difference. Flow boiling with microchannels has shown a great potential with its high surface area to volume ratio and latent heat removal. However, flow instabilities and early critical heat flux (CHF) have prevented its successful implementation. A novel flow boiling design based on a mechanistic approach is taken to overcome the above mentioned disadvantages while presenting a very low pressure drop. The design uses open microchannels with tapered manifold (OMM) to provide stable and efficient operation. The tapered manifold above the microchannels provides an increasing cross-sectional area in the flow direction. The extra flow cross-sectional area allows bubbles to emerge from the microchannels and expand in the manifold along the flow direction. Using a 6% taper and a moderately high inlet liquid flow Reynolds number of 1095, a CHF of 1.07 kW/cm^2 with a heat transfer coefficient of 295 kW/m^2°C and a pressure drop of 30 kPa was recorded. Baseline test with uniform manifold were conducted and compared with tapered geometry. The experimental data was substantiated with pressure drop modeling for the new geometry. High speed visualization was also conducted to understand the underlying mechanism in the tapered configuration."--Abstract.

Encyclopedia of Two-Phase Heat Transfer and Flow IV

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Publisher : World Scientific Publishing
ISBN 13 : 9813234385
Total Pages : 1372 pages
Book Rating : 4.8/5 (132 download)

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Book Synopsis Encyclopedia of Two-Phase Heat Transfer and Flow IV by : John R Thome

Download or read book Encyclopedia of Two-Phase Heat Transfer and Flow IV written by John R Thome and published by World Scientific Publishing. This book was released on 2018-05-18 with total page 1372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Set IV is a new addition to the previous Sets I, II and III. It contains 23 invited chapters from international specialists on the topics of numerical modeling of pulsating heat pipes and of slug flows with evaporation; lattice Boltzmann modeling of pool boiling; fundamentals of boiling in microchannels and microfin tubes, CO2 and nanofluids; testing and modeling of micro-two-phase cooling systems for electronics; and various special topics (flow separation in microfluidics, two-phase sensors, wetting of anisotropic surfaces, ultra-compact heat exchangers, etc.). The invited authors are leading university researchers and well-known engineers from leading corporate research laboratories (ABB, IBM, Nokia Bell Labs). Numerous 'must read' chapters are also included here for the two-phase community. Set IV constitutes a 'must have' engineering and research reference together with previous Sets I, II and III for thermal engineering researchers and practitioners.

Flow boiling and condensation in microscale channels

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Publisher : Springer Nature
ISBN 13 : 303068704X
Total Pages : 290 pages
Book Rating : 4.0/5 (36 download)

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Book Synopsis Flow boiling and condensation in microscale channels by : Fabio Toshio Kanizawa

Download or read book Flow boiling and condensation in microscale channels written by Fabio Toshio Kanizawa and published by Springer Nature. This book was released on 2021-04-30 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers aspects of multiphase flow and heat transfer during phase change processes, focusing on boiling and condensation in microscale channels. The authors present up-to-date predictive methods for flow pattern, void fraction, pressure drop, heat transfer coefficient and critical heat flux, pointing out the range of operational conditions that each method is valid. The first four chapters are dedicated on the motivation to study multiphase flow and heat transfer during phase change process, and the three last chapters are focused on the analysis of heat transfer process during boiling and condensation. During the description of the models and predictive methods, the trends are discussed and compared with experimental findings.

Convective Boiling and Condensation

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Publisher : Clarendon Press
ISBN 13 : 0191591262
Total Pages : 646 pages
Book Rating : 4.1/5 (915 download)

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Book Synopsis Convective Boiling and Condensation by : John G. Collier

Download or read book Convective Boiling and Condensation written by John G. Collier and published by Clarendon Press. This book was released on 1994-05-19 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: * Third edition of a well-known and well established text both in industry and for teaching * Fully up-to-date and includes extra problems This book is an aid to heat exchanger design written primarily for design and development engineers in the chemical process, power generation, and refrigeration industries. It provides a comprehensive reference on two-phase flows, boiling, and condensation. The text covers all the latest advances like flows over tube bundles and two-phase heat transfer regarding refrigerants and petrochemicals. Another feature of this third edition is many new problems at chapter ends to enhance its use as a teaching text for graduate and post-graduate courses on two-phase flow and heat transfer. - ;This book is written for practising engineers as a comprehensive reference on two-phase flows, boiling, and condensation. It deals with methods for estimating two-phase flow pressure drops and heat transfer rates. It is a well-known reference book in its third edition and is also used as a text for advanced university courses. Both authors write from practical experience as both are professional engineers. -

Flow Boiling in Microgap Channels

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Publisher : Springer Science & Business Media
ISBN 13 : 1461471907
Total Pages : 88 pages
Book Rating : 4.4/5 (614 download)

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Book Synopsis Flow Boiling in Microgap Channels by : Tamanna Alam

Download or read book Flow Boiling in Microgap Channels written by Tamanna Alam and published by Springer Science & Business Media. This book was released on 2013-08-26 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow Boiling in Microgap Channels: Experiment, Visualization and Analysis presents an up-to-date summary of the details of the confined to unconfined flow boiling transition criteria, flow boiling heat transfer and pressure drop characteristics, instability characteristics, two phase flow pattern and flow regime map and the parametric study of microgap dimension. Advantages of flow boiling in microgaps over microchannels are also highlighted. The objective of this Brief is to obtain a better fundamental understanding of the flow boiling processes, compare the performance between microgap and conventional microchannel heat sinks, and evaluate the microgap heat sink for instabilities and hotspot mitigation.

VDI Heat Atlas

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Publisher : Springer Science & Business Media
ISBN 13 : 3540778764
Total Pages : 1608 pages
Book Rating : 4.5/5 (47 download)

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Book Synopsis VDI Heat Atlas by : VDI Gesellschaft

Download or read book VDI Heat Atlas written by VDI Gesellschaft and published by Springer Science & Business Media. This book was released on 2010-07-21 with total page 1608 pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than 50 years, the Springer VDI Heat Atlas has been an indispensable working means for engineers dealing with questions of heat transfer. Featuring 50% more content, this new edition covers most fields of heat transfer in industrial and engineering applications. It presents the interrelationships between basic scientific methods, experimental techniques, model-based analysis and their transfer to technical applications.

Compact Heat Exchangers

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Publisher : CRC Press
ISBN 13 : 9781560320128
Total Pages : 798 pages
Book Rating : 4.3/5 (21 download)

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Book Synopsis Compact Heat Exchangers by : Alexander Louis London

Download or read book Compact Heat Exchangers written by Alexander Louis London and published by CRC Press. This book was released on 1990 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat exchangers are a crucial part of aerospace, marine, cryogenic and refrigeration technology. These essays cover such topics as complicated flow arrangements, complex extended surfaces, two-phase flow and irreversibility in heat exchangers, and single-phase heat transfer.

Thermal Design of Electronic Equipment

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Publisher : CRC Press
ISBN 13 : 1351835912
Total Pages : 440 pages
Book Rating : 4.3/5 (518 download)

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Book Synopsis Thermal Design of Electronic Equipment by : Ralph Remsburg

Download or read book Thermal Design of Electronic Equipment written by Ralph Remsburg and published by CRC Press. This book was released on 2017-12-19 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a field where change and growth is inevitable, new electronic packaging problems continually arise. Smaller, more powerful devices are prone to overheating, causing intermittent system failures, corrupted signals, lower MTBF, and outright system failure. Since convection cooling is the heat transfer path most engineers take to deal with thermal problems, it is appropriate to gain as much understanding about the underlying mechanisms of fluid motion as possible. Thermal Design of Electronic Equipment is the only book that specifically targets the formulas used by electronic packaging and thermal engineers. It presents heat transfer equations dealing with polyalphaolephin (PAO), silicone oils, perfluorocarbons, and silicate ester-based liquids. Instead of relying on theoretical expressions and text explanations, the author presents empirical formulas and practical techniques that allow you to quickly solve nearly any thermal engineering problem in electronic packaging.

Next Generation Microchannel Heat Exchangers

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Publisher : Springer Science & Business Media
ISBN 13 : 1461407796
Total Pages : 124 pages
Book Rating : 4.4/5 (614 download)

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Book Synopsis Next Generation Microchannel Heat Exchangers by : Michael Ohadi

Download or read book Next Generation Microchannel Heat Exchangers written by Michael Ohadi and published by Springer Science & Business Media. This book was released on 2012-10-16 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Next Generation Microchannel Heat Exchangers, the authors’ focus on the new generation highly efficient heat exchangers and presentation of novel data and technical expertise not available in the open literature. Next generation micro channels offer record high heat transfer coefficients with pressure drops much less than conventional micro channel heat exchangers. These inherent features promise fast penetration into many mew markets, including high heat flux cooling of electronics, waste heat recovery and energy efficiency enhancement applications, alternative energy systems, as well as applications in mass exchangers and chemical reactor systems. The combination of up to the minute research findings and technical know-how make this book very timely as the search for high performance heat and mass exchangers that can cut costs in materials consumption intensifies.

Handbook of Thermal Management Systems

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Publisher : Elsevier
ISBN 13 : 0443190186
Total Pages : 862 pages
Book Rating : 4.4/5 (431 download)

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Book Synopsis Handbook of Thermal Management Systems by : Fethi Aloui

Download or read book Handbook of Thermal Management Systems written by Fethi Aloui and published by Elsevier. This book was released on 2023-08-24 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Thermal Management Systems: e-Mobility and Other Energy Applications is a comprehensive reference on the thermal management of key renewable energy sources and other electronic components. With an emphasis on practical applications, the book addresses thermal management systems of batteries, fuel cells, solar panels, electric motors, as well as a range of other electronic devices that are crucial for the development of sustainable transport systems. Chapters provide a basic understanding of the thermodynamics behind the development of a thermal management system, update on Batteries, Fuel Cells, Solar Panels, and Other Electronics, provide a detailed description of components, and discuss fundamentals. Dedicated chapters then systematically examine the heating, cooling, and phase changes of each system, supported by numerical analyses, simulations and experimental data. These chapters include discussion of the latest technologies and methods and practical guidance on their application in real-world system-level projects, as well as case studies from engineering systems that are currently in operation. Finally, next-generation technologies and methods are discussed and considered. Presents a comprehensive overview of thermal management systems for modern electronic technologies related to energy production, storage and sustainable transportation Addresses the main bottlenecks in the technology development for future green and sustainable transportation systems Focuses on the practical aspects and implementation of thermal management systems through industrial case studies, real-world examples, and solutions to key problems

Principles of Enhanced Heat Transfer

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Publisher : Wiley-Interscience
ISBN 13 :
Total Pages : 584 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Principles of Enhanced Heat Transfer by : Ralph L. Webb

Download or read book Principles of Enhanced Heat Transfer written by Ralph L. Webb and published by Wiley-Interscience. This book was released on 1994-03-28 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Indeed, today "second generation" enhancement concepts are routing in the automotive and refrigeration industries to obtain lower cost, smaller heat exchanger size, and higher energy efficiency in system operation. And the aerospace, process, and power generation industries are not far behind.