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Heat Transfer And Pressure Drop In Microchannels With Different Inlet Geometries For Laminar And Transitional Flow Of Water
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Book Synopsis Heat Transfer and Pressure Drop in Microchannels with Different Inlet Geometries for Laminar and Transitional Flow of Water by : D.V. Garach
Download or read book Heat Transfer and Pressure Drop in Microchannels with Different Inlet Geometries for Laminar and Transitional Flow of Water written by D.V. Garach and published by . This book was released on 2014 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Heat Transfer and Pressure Drop in Flow Boiling in Microchannels by : Sujoy Kumar Saha
Download or read book Heat Transfer and Pressure Drop in Flow Boiling in Microchannels written by Sujoy Kumar Saha and published by Springer. This book was released on 2015-07-08 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief addresses the phenomena of heat transfer and pressure drop in flow boiling in micro channels occurring in high heat flux electronic cooling. A companion edition in the Springer Brief Subseries on Thermal Engineering and Applied Science to “Critical Heat Flux in Flow Boiling in Micro channels,” by the same author team, this volume is idea for professionals, researchers and graduate students concerned with electronic cooling.
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.
Book Synopsis Fluid Flow, Heat Transfer and Boiling in Micro-Channels by : L. P. Yarin
Download or read book Fluid Flow, Heat Transfer and Boiling in Micro-Channels written by L. P. Yarin and published by Springer Science & Business Media. This book was released on 2008-09-19 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of the book is uid dynamics and heat transfer in micro-channels. This problem is important for understanding the complex phenomena associated with single- and two-phase ows in heated micro-channels. The challenge posed by high heat uxes in electronic chips makes thermal management a key factor in the development of these systems. Cooling of mic- electronic components by new cooling technologies, as well as improvement of the existing ones, is becoming a necessity as the power dissipation levels of integrated circuits increases and their sizes decrease. Miniature heat sinks with liquid ows in silicon wafers could signi cantly improve the performance and reliability of se- conductor devices. The improvements are made by increasing the effective thermal conductivity, by reducing the temperature gradient across the wafer, by reducing the maximum wafer temperature, and also by reducing the number and intensity of localized hot spots. A possible way to enhance heat transfer in systems with high power density is to change the phase in the micro-channels embedded in the device. This has motivated a number of theoretical and experimental investigations covering various aspects of heat transfer in micro-channel heat sinks with phase change. The ow and heat transfer in heated micro-channels are accompanied by a n- ber of thermohydrodynamic processes, such as liquid heating and vaporization, bo- ing, formation of two-phase mixtures with a very complicated inner structure, etc., which affect signi cantly the hydrodynamic and thermal characteristics of the co- ing systems.
Book Synopsis Handbook of Single-Phase Convective Heat Transfer by : Sadik Kakaç
Download or read book Handbook of Single-Phase Convective Heat Transfer written by Sadik Kakaç and published by Wiley-Interscience. This book was released on 1987-11-03 with total page 1268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Good,No Highlights or Markup,all pages are intact.
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.
Book Synopsis Laminar Flow Forced Convection Heat Transfer Behavior of Phase Change Material Fluid in Straight and Staggered Pin Microchannels by : Satyanarayana Kondle
Download or read book Laminar Flow Forced Convection Heat Transfer Behavior of Phase Change Material Fluid in Straight and Staggered Pin Microchannels written by Satyanarayana Kondle and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microchannels have been studied extensively for electronic cooling applications ever since they were found to be effective in removing high heat flux from small areas. The rate of heat removed using microchannels depends on many factors including the geometry shape, solid and fluid materials used, and surface roughness, among others. Many configurations of microchannels have been studied with various materials and compared for their effectiveness in heat removal. However, there is little research done so far in using Phase Change Material (PCM) fluids and pin fins in microchannels to enhance the heat transfer. PCM fluids exhibit greater heat transfer when the phase change material undergoes liquid-to-solid transformation. Staggered pins in microchannels have also shown higher heat removal characteristics because of the continuous breaking and formation of the thermal and hydrodynamic boundary layer; they also exhibit higher pressure drop because pins act as flow obstructers. This paper presents numerical results of circular, square, straight rectangular microchannels with various aspect ratios (1:2, 1:4 and 1:8), and rectangular microchannels with two characteristic staggered pins (square and circular, fixed height with no variation in aspect ratio). The heat transfer performance of a single phase fluid and PCM fluid in all of these microchannels and the corresponding pressure drop characteristics are also presented. An effective specific heat capacity model was used to account for the phase change process of PCM fluid. Comparison of heat transfer characteristics of single phase fluid and PCM fluid are presented for all the geometries considered. Among the straight microchannels, 1:8 geometry was found to have the highest Nusselt number. The use of PCM fluid in straight microchannels increased the Nusselt number by 3-7 percent compared to the single phase fluids. Among the staggered pin microchannels, circular pins were found to be more effective in terms of heat transfer by exhibiting higher Nusselt number. Circular pin microchannels were also found to have lower pressure drop compared to the square pin microchannels. Overall, for all the geometries considered, it was found that the PCM fluid enhances the heat transfer compared to the SPF fluid.
Download or read book Advances in Heat Transfer written by and published by Academic Press. This book was released on 2019-10-24 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Transfer, Volume 51, provides in-depth review articles from a broader scope than in traditional journals or texts, with this comprehensive release covering chapters on Micro and nanoparticle transport phenomena in confined flows, A review of heat transfer in the transitional flow regime, and much more. Fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in traditional journals or texts Provides essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer Presents a great resource for use in graduate school level courses
Book Synopsis Instability in Flow Boiling in Microchannels by : Sujoy Kumar Saha
Download or read book Instability in Flow Boiling in Microchannels written by Sujoy Kumar Saha and published by Springer. This book was released on 2015-09-14 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief addresses the phenomena of instability in flow boiling in microchannels occurring in high heat flux electronic cooling. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Critical Heat Flux in Flow Boiling in Microchannels,” and "Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,"by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.
Book Synopsis Analysis of Conjugate Heat Transfer and Pressure Drop in Microchannels for Different Aspects Ratios by : Marc Robert Greenland
Download or read book Analysis of Conjugate Heat Transfer and Pressure Drop in Microchannels for Different Aspects Ratios written by Marc Robert Greenland and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study the heat transfer and hydrodynamic parameters were experimentally investigated for a single microchannel housed in a stainless steel solid base material for different aspect ratios in the laminar regime with water as the working fluid. The stainless steel base material had a low thermal conductivity (15.1 W / mK) which magnified the conjugative effects in order to better understand the heat transfer. Rectangular microchannels with a height and width of 0.64 mm x 0.41 mm for Test Section 1, 0.5 mm x 0.5 mm for Test Section 2 and 0.43 mm x 0.58 mm for Test Section 3 were considered. The overall width of the solid substrate was 1.5 mm and the length was 50 mm for all of the test sections. The aspect ratio of the channel and the solid substrate was kept equal. A constant heat flux of 10 W / cm2 was applied to the bottom outer wall of the test section. A sudden contraction inlet and a sudden expansion outlet manifold contained pressure ports, to measure the pressure drop across the test sections, and thermocouples measured the mean inlet and outlet fluid temperatures. Thermocouples were used to measure the outer top and side wall temperatures at four equally spaced positions along the axial direction. The amount of axial heat conduction was below 0.6 % for all of the test sections and therefore warranted the use of a two-dimensional conduction model to determine the heat transfer parameters at the fluid to solid interface based on the outer measured wall temperatures. The local Nusselt number decreased, along the axial direction but increased towards the exit for all of the test sections. The average Nusselt number increased with the flow rate and the critical Reynolds number for fully turbulent flow Test Section 1 was 1950, for Test Section 2 was 2250 and for Test Section 3 was 1650. The average Nusselt number was directly related to the perimeter of the microchannels two side walls and the bottom wall (not the top wall), and thus decreased as the aspect ratio of the channel increased. The experimentally determined Nusselt numbers were larger for all three test sections when compared to common acceptable correlations. The friction factor decreased with the flow rate and was smaller in magnitude when compared to conventional theories. The diabatic friction factor magnitudes were smaller than the adiabatic friction factors. The friction factor decreased as the aspect ratio decreased, where the aspect ratio was calculated by taking the maximum of the microchannels width or height, divided by the minimum of the two. The possibility of a relationship could exist between the Colburn j-factor and the friction factor when considering the results for Test Section 1 and Test Section 2 but the results for Test Section 3 were significantly different.
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.
Book Synopsis Fluid Mechanics and Fluid Power (Vol. 3) by : Suvanjan Bhattacharyya
Download or read book Fluid Mechanics and Fluid Power (Vol. 3) written by Suvanjan Bhattacharyya and published by Springer Nature. This book was released on 2023-04-17 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the select proceedings of the 48th National Conference on Fluid Mechanics and Fluid Power (FMFP 2021) held at BITS Pilani in December 2021. It covers the topics such as fluid mechanics, measurement techniques in fluid flows, computational fluid dynamics, instability, transition and turbulence, fluid‐structure interaction, multiphase flows, micro- and nanoscale transport, bio-fluid mechanics, aerodynamics, turbomachinery, propulsion and power. The book will be useful for researchers and professionals interested in the broad field of mechanics.
Book Synopsis Critical Heat Flux in Flow Boiling in Microchannels by : Sujoy Kumar Saha
Download or read book Critical Heat Flux in Flow Boiling in Microchannels written by Sujoy Kumar Saha and published by Springer. This book was released on 2015-06-04 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief concerns the important problem of critical heat flux in flow boiling in microchannels. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,” by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.
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.
Book Synopsis Phase Separation in Two-phase Microfluidic Heat Exchangers by : Milnes P. David
Download or read book Phase Separation in Two-phase Microfluidic Heat Exchangers written by Milnes P. David and published by Stanford University. This book was released on 2011 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase microfluidic heat exchangers have the potential to meet the large heat dissipation demands of high power electronics and computing systems. Two-phase cooling systems face practical challenges brought on by the growth and advection of the vapor phase in the confined geometries, which lead to large pressure drops, increased thermal resistance and the formation of detrimental flow instabilities. One proposed solution to these issues is phase separation, whereby the vapor is locally separated from the two-phase flow through a porous hydrophobic membrane. This dissertation describes a series of studies conducted to develop an understanding of the factors that influence vapor separation and its impact on the hydraulic and thermal characteristics of two-phase heat exchangers. Flow phenomena are a critical component in developing this understanding of phase separation. High speed visualization of adiabatic and diabatic vaporizing flows was carried out in a single 124[Mu]m by 98[Mu]m copper microchannel with a 65[Mu]m thick, 220nm pore diameter hydrophobic PTFE membrane wall. During adiabatic air-water flow, wavy-stratified and stratified flow dominated lower liquid velocities, while plug and annular type flows dominated at the higher velocities. Analysis found that air removal could be improved by increasing the venting area, increasing the trans-membrane pressure or using thinner, high permeability membranes. Diabatic water-vapor experiments with mass flux velocities of 140 and 340 kg/s-m2 and exit qualities up to 20% found that stratified type flows dominate at lower mass fluxes while cyclical churn-annular flow became more prevalent at the higher mass-flux and quality. The observed flow regimes are hypothesized to play a significant role in determining the pressure drop and heat transfer coefficient during flow boiling. To study the impact of various geometric and membrane factors on the performance of a phase separating microchannel heat exchanger dissipating 100W of heat, a numerical model incorporating vapor separation and transport during two-phase flow boiling in a microchannel was developed. The impact of substrate thermal conductivity and thickness, membrane permeability and thickness, liquid channel density, liquid and vent channel diameter and vent-to-liquid channel diameter ratio was studied and compared for a standard non-venting heat exchanger, a vapor venting heat exchanger and a non-venting heat exchanger occupying the same increased volume as the venting heat exchanger. The numerical study found that the venting heat exchanger had improved pressure drop and device temperatures for all tested conditions when compared against a standard heat exchanger but only under very limited conditions when compared against the volumetrically equivalent non-venting heat exchanger. The study indicates that the best venting heat exchanger performance is achieved when the membrane conductance is of the same order or higher than that of the microchannel; this can be achieved through the use of thin high permeability membranes coupled with small hydraulic diameter microchannels. Finally, a study was conducted to explore the fabrication methods to build a vapor separating heat exchanger and to quantify the operating performance of multichannel silicon and copper phase separating devices. A copper parallel microchannel heat exchanger with nineteen 130[Mu]m square microchannels was built and tested at heat fluxes of up to 820 kW/m2 and water mass fluxes of between 102 and 420 kg/s-m2. Normalized pressure drop was improved by as much as 60% and average substrate temperature by a maximum of 4.4°C between the non-venting control and vapor venting device under similar operating conditions. Comparison between the experimental results and simulation predictions found higher than expected pressure drop improvements at higher mass fluxes and poorer heat transfer coefficients at the lowest mass flux. Based on the flow phenomena study these discrepancies are believed to be due to the mass flux and vapor quality dependent two-phase flow structures. The encouraging experimental and numerical results motivate further study into phase separation methods, materials and flow physics. The development of a high performance phase separating heat exchanger, with the thermal benefits of two-phase boiling flow and the hydraulic benefits of single-phase liquid flow, would strongly enable the adoption and application of two-phase heat exchangers to provide effective and efficient cooling for next generation high power computing systems.
Book Synopsis Enhanced Flow Boiling Heat Transfer in Radial Microchannel and Offset Strip Fin Geometries by : Alyssa Recinella
Download or read book Enhanced Flow Boiling Heat Transfer in Radial Microchannel and Offset Strip Fin Geometries written by Alyssa Recinella and published by . This book was released on 2016 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Devices used for various electronic purposes are increasing in power consumption and performance. Due to this growth, the amount of heat dissipated over a small surface area has proportionally continued to increase. Despite previous efforts involving single phase natural and forced convection, these methods are no longer effective in high heat removal. Research in two-phase liquid cooling has become more prominent. Boiling has the potential to yield large critical heat flux values, high heat transfer coefficients and lower pressure drops. Many different surface enhancements and working fluids have been tested to increase efficiency and minimize heat losses. Flow boiling in microchannels have been widely explored in literature for high heat flux dissipation. Microchannels are compact and subsequently easy to manufacture. However, due to flow instabilities that accompany microchannels, different configurations and additional modifications have been explored in order to maximize performance. In this work, a radial geometry is experimentally investigated with a flow inlet over the center of the chip. This central inlet creates a reduction in flow length and therefore a reduction in pressure drop and flow instabilities. Two testing surfaces were explored including a radial microchannel array and a radial offset strip fin array. To maximize performance even further, a gap has been added between the cover plate and testing surface to increase flow area and reduce pressure drop. One significant observation shows that an increase in flow rate mitigates the instabilities seen in the channels and prolongs critical heat flux (CHF). Due to these phenomena, all configurations are tested in the modified configuration with higher flow rates ranging from 120-320 mL/min. Radial microchannels with an added gap yielded maximum performance values of 385.5 W/cm^2 at 42.7°C wall superheat with a high pressure drop of about 140 kPa while the offset strip fin configuration achieved much higher heat transfer performance with CHF values exceeding 900 W/cm^2 at 58.6°C wall superheat. The offset strip fin geometry shows significant performance enhancements compared to the microchannels. For both the gap geometries and the closed geometries, the offset values are much higher than the radial microchannels."--Abstract.
Book Synopsis Heat Transfer And Fluid Flow In Microchannels by : Gian Piero Celata
Download or read book Heat Transfer And Fluid Flow In Microchannels written by Gian Piero Celata and published by Begell House Publishers. This book was released on 2004-08-01 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
