Download or read book Microjet Array Impingement Heat Transfer Crossflow Effects in Single phase and Flow Boiling written by Brian M. Werneke and published by . This book was released on 2015 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Single phase and Flow Boiling Submerged and Confined Microjet Array Heat Transfer written by Eric Browne and published by . This book was released on 2010 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Single Phase and Boiling Jet Impingement Heat Transfer written by Sanjeev K. Hingorani and published by . This book was released on 1996 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Submerged Jet Impingement Boiling Thermal Management written by Ruander Cardenas and published by . This book was released on 2011 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technologies such as avionics and power electronics are driving the demand for thermal management schemes towards high heat fluxes and low surface temperatures. Typically, these applications require the dissipation of heat fluxes in the rage of 100-1000 W/cm2 while maintaining surface temperatures lower than about 85 °C. Phase-change heat transfer schemes such as pool boiling, flow boiling in mini/micro-channel heat sinks, and sprays and jet impingement boiling are frequently used to meet this demand. This dissertation documents global heat transfer characteristics of submerged jet impingement boiling for high heat flux, low surface temperature applications. The effect of geometrical and flow parameters on heat transfer performance are examined for a single circular jet using water and FC-72 as working fluids. Exclusive to this study is the comparison of distinct jet fluids at a fixed saturation temperature, which is achieved by comparing sub-atmospheric jet impingement boiling data of water with atmospheric FC-72 experiments. Under sub-atmospheric conditions, the liquid-to-vapor density ratio of water is within a range that has not been studied in previous jet impingement boiling experiments. Varied geometrical parameters include the surface-to-nozzle diameter ratio, surface roughness, and jet configuration. Varied fluidic parameters include pressure, jet exit Reynolds number, fluid subcooling, and fluid properties. Global experimental data collected during this study are used to document the relationship between surface temperature and surface heat flux through boiling curves. The global data are augmented by qualitative high-speed visualization. Experimental data demonstrate enhanced heat transfer capabilities beyond those of pool boiling by using a submerged impinging jet. For a fixed saturation temperature, significantly higher heat transfer rates are attainable using water in comparison to FC-72. A CHF map for submerged jet impingement boiling is developed based on experimental evidence. A general submerged jet impingement CHF correlation is developed based on a well known CHF model in literature. A novel, passive means of preventing temperature overshoot of highly-wetting fluids during submerged jet impingement boiling is introduced.
Download or read book Flow Boiling Heat Transfer in Narrow Vertical Channels written by and published by Cuvillier Verlag. This book was released on 2004-10-14 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Saturated flow boiling heat transfer and flow visualization experiments were carried out in three vertical rectangular channels with dimensions (width×height) 2.0×4.0, 0.86×2.0 and 0.54×1.60 mm² (corresponding to hydraulic diameters 2.67, 1.20 and 0.81 mm, respectively). The channels were heated from three sides. Deionized water was used as the working fluid. The channel exit was at atmospheric pressure. Benchmark experiments of single-phase flow were also conducted for pressure drop and heat transfer. Experimental results show that for the 0.54×1.60 mm² channel, the singlephase friction factor is higher than predicted by well-accepted correlations, while for the other two channels it can be well correlated. The heat transfer performance for both laminar and turbulent regimes under asymmetric heating conditions is different from that under uniform heating conditions on which the existing correlations are based. Therefore single-phase heat transfer correlations were modified so that they could be incorporated into the two-phase heat transfer correlations employed for asymmetric heating conditions. For flow boiling, three basic flow patterns are observed for all the channels, viz., bubbly, slug and annular flow. However, based on the developed flow pattern maps, the transition from slug to annular flow for the 2.0×4.0 mm² channel occurs at a lower superficial vapor velocity than for the two small channels. This suggests that the nucleate boiling mechanism, which generally corresponds to slug flow, is more important for the two small channels. Saturated flow boiling heat transfer characteristics were investigated under different heat flux, mass flux and vapor quality. The experimental local heat transfer coefficient for the 2.0×4.0 mm² channel is in good agreement with the modified Kandlikar correlation and the Shah correlation. For the smaller channels (0.86×2.0 mm² and 0.54×1.60 mm²), the heat transfer characteristics are not dominated by the convective boiling mechanism. On the contrary, the nucleate boiling term of the Kandlikar correlation predicts the experimental heat transfer coefficient relatively well. Two new correlations have been developed in which the local two-phase heat transfer coefficient is related to the single-phase heat transfer coefficient by a twophase multiplier, which is a function of the Boiling number and thermodynamic vapor quality. The developed correlations show rather good agreement with experimental results.
Download or read book Cross Flow Boiling in Tube Bundles written by S. C. Yao and published by . This book was released on 1982 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research on boiling in confined spaces has been completed. This problem is of great importance to the boiling induced corrosion in the steam generator crevices between the tube and the support structures. In the report of 1981, analysis of single phase flow, two phase flow, and dryout in crevices have been presented. Experimental results of boiling and dryout in vertical crevices with closed bottom were also reported. In the report of 1982, the results of forced convective boiling heat transfer and critical heat flux in crevices are shown. In this report, the boiling heat transfer and critical heat flux in horizontal crevices are reported. The research on cross flow boiling in tube bundles proceeds smoothly. In this report, the analysis of single phase flow pressure drop and convective heat transfer in tube bundles at cross flow of very low or very high Reynolds numbers are presented. The experimental setup has been completed and data are taken presently.
Download or read book Heat Transfer Enhancement of Single phase Flow and Flow Boiling in Microchannels an Experimental Study written by Yingying Wang and published by . This book was released on 2014 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Single phase and Boiling Flow in Microchannels with High Heat Flux written by Elmer Galvis and published by . This book was released on 2012 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: A cooling system for high heat flux applications is examined using microchannel evaporators with water as the working fluid and boiling as the heat transfer mechanism. Experimental studies are performed using single channel microevaporators allowing for better control of the flow mechanics unlike other investigations where multiple, parallel, flow channels can result in a non-uniform distribution of the working fluid. High-speed flow visualizations are performed in conjunction with heat transfer and pressure drop measurements to support the quantitative experimental data. Flow patterns associated with a range of boundary conditions are characterized and then presented in the form of novel flow regime maps that intrinsically reflect the physical mechanisms controlling two-phase pressure distributions and heat transfer behavior. Given the complexity associated with modeling of boiling heat transfer and the lack of a universal model that provides accurate predictions across a broad spectrum of flow conditions, flow regime maps serve as a valuable modeling aid to assist in targeted modeling over specific flow regimes. This work represents a novel and original contribution to the understanding of boiling mechanisms for water in microchannels. The flow patterns in this work are found to be closely coupled with mass flux, heat flux, and channel size; where re-wetting and pressure oscillations play a crucial role, and are likely responsible for its development and evolution. Reversed flow, typically attributed to a non-uniform fluid distribution in multiple channel microevaporators by other researchers, is shown to be a result of the upstream expansion of confined bubbles. During flow boiling, the pressure drop in the microchannel increases with the heat flux for a constant flow rate due to the significant acceleration effects associated with smaller channels, unlike in single-phase flow where the pressure drop is constant. Water flow boiling in rectangular microchannels, although not extensively explored in the published literature, provides an extremely high cooling capacity, with dissipation rates approaching 440 W/cm2, making this an ideal candidate for cooling of next generation electronic systems. Single-phase flow studies revealed that pressure and heat transfer coefficient macroscale models are transferable to microchannels with hydraulic diameters down to 200 [mu]m, when the entrance effects and minor losses are properly considered. These studies include laminar developing flow conditions not commonly considered in the literature and fully developed flow. Since the applicability of macroscale theories to microchannels is often questioned, this investigation helps clarify this issue for microchannels within the range of experimental conditions explored in this work. Finally, new correlations for the hydrodynamic entrance length are proposed for rectangular microchannels and good agreement is found when compared with published experimental data over a wide range of Reynolds number. These correlations are more accurate, and original in the sense that they incorporate the effects of channel aspect ratio, and include creeping flow conditions which are currently unavailable for rectangular microchannels. This work represents a major advance in the development of new cooling systems for high heat flux applications requiring dissipation rates in excess of 100 W/cm2.
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.
Download or read book Fundamentals of Multiphase Flow written by Christopher E. Brennen and published by Cambridge University Press. This book was released on 2005-04-18 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book Cooling of Electronic Systems written by Sadik Kakaç and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 953 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic technology is developing rapidly and, with it, the problems associated with the cooling of microelectronic equipment are becoming increasingly complex. So much so that it is necessary for experts in the fluid and thermal sciences to become involved with the cooling problem. Such thoughts as these led to an approach to leading specialists with a request to contribute to the present book. Cooling of Electronic Systems presents the technical progress achieved in the fundamentals of the thermal management of electronic systems and thermal strategies for the design of microelectronic equipment. The book starts with an introduction to the cooling of electronic systems, involving such topics as trends in computer system cooling, the cooling of high performance computers, thermal design of microelectronic components, natural and forced convection cooling, cooling by impinging air and liquid jets, thermal control systems for high speed computers, together with a detailed review of advances in manufacturing and assembly technology. Following this, practical methods for the determination of the parameters required for the thermal analysis of electronic systems and the accurate prediction of temperature in consumer electronics. Cooling of Electronic Systems is currently the most up-to-date book on the thermal management of electronic and microelectronic equipment, and the subject is presented by eminent scientists and experts in the field. Vital reading for all designers of modern, high-speed computers.
Download or read book Heat Transfer in Gas Turbine Systems written by Richard J. Goldstein and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores recent developments in heat transfer and thermal control applied to modern high-temperature gas turbine systems. It examines experimental results and techniques computational studies and methods and design recommendations. Aspects of heat transfer in rotating machinery are studied as well as thermal aspects of other sections of the turbine (e.g. the compressor). Proceedings of an August 2000 conference.
Download or read book Bubbly Flows written by Martin Sommerfeld and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.
Download or read book Microscale Flow and Heat Transfer written by Amit Agrawal and published by Springer. This book was released on 2019-05-25 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers concepts and the latest developments on microscale flow and heat transfer phenomena involving a gas. The book is organised in two parts: the first part focuses on the fluid flow and heat transfer characteristics of gaseous slip flows. The second part presents modelling of such flows using higher-order continuum transport equations. The Navier-Stokes equations based solution is provided to various problems in the slip regime. Several interesting characteristics of slip flows along with useful empirical correlations are documented in the first part of the book. The examples bring out the failure of the conventional equations to adequately describe various phenomena at the microscale. Thereby the readers are introduced to higher order continuum transport (Burnett and Grad) equations, which can potentially overcome these limitations. A clear and easy to follow step by step derivation of the Burnett and Grad equations (superset of the Navier-Stokes equations) is provided in the second part of the book. Analytical solution of these equations, the latest developments in the field, along with scope for future work in this area are also brought out. Presents characteristics of flow in the slip and transition regimes for a clear understanding of microscale flow problems; Provides a derivation of Navier-Stokes equations from microscopic viewpoint; Features a clear and easy to follow step-by-step approach to derive Burnett and Grad equations; Describes a complete compilation of few known exact solutions of the Burnett and Grad equations, along with a discussion of the solution aided with plots; Introduces the variants of the Navier-Stokes, Burnett and Grad equations, including the recently proposed Onsager-Burnett and O13 moment equations.
Download or read book Energy Efficiency written by Thomas D. Eastop and published by Longman Publishing Group. This book was released on 1990 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: The finite nature of fossil fuels such as coal, oil and natural gas, the increasing worry about the greenhouse effect and the growing amount of power used in the world means that alternative energy sources such as wind, tide and sun must be seriously considered. But this will take time and money. In the immediate future the most direct and cost-effective way to tackle the problem is to conserve existing sources of energy and this book concentrates on this theme.
Download or read book The IGBT Device written by B. Jayant Baliga and published by William Andrew. This book was released on 2015-03-06 with total page 733 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IGBT device has proved to be a highly important Power Semiconductor, providing the basis for adjustable speed motor drives (used in air conditioning and refrigeration and railway locomotives), electronic ignition systems for gasolinepowered motor vehicles and energy-saving compact fluorescent light bulbs. Recent applications include plasma displays (flat-screen TVs) and electric power transmission systems, alternative energy systems and energy storage. This book is the first available to cover the applications of the IGBT, and provide the essential information needed by applications engineers to design new products using the device, in sectors including consumer, industrial, lighting, transportation, medical and renewable energy. The author, B. Jayant Baliga, invented the IGBT in 1980 while working for GE. His book will unlock IGBT for a new generation of engineering applications, making it essential reading for a wide audience of electrical engineers and design engineers, as well as an important publication for semiconductor specialists. Essential design information for applications engineers utilizing IGBTs in the consumer, industrial, lighting, transportation, medical and renewable energy sectors. Readers will learn the methodology for the design of IGBT chips including edge terminations, cell topologies, gate layouts, and integrated current sensors. The first book to cover applications of the IGBT, a device manufactured around the world by more than a dozen companies with sales exceeding $5 Billion; written by the inventor of the device.
