A Study of Two Phase, One Component Annular Flow with Condensation

A Study of Two Phase, One Component Annular Flow with Condensation PDF Author: Cho Ying Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 142

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A Study of Two Phase, One Component Annular Flow with Condensation

A Study of Two Phase, One Component Annular Flow with Condensation PDF Author: Cho Ying Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 142

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Book Description


0-g Annular Flow and 1-g Stratified Flow Single Component Two- Phase Condensation Modeling and Experiments

0-g Annular Flow and 1-g Stratified Flow Single Component Two- Phase Condensation Modeling and Experiments PDF Author: Pascale Baranek
Publisher:
ISBN:
Category : Two-phase flow
Languages : en
Pages : 182

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Two-Phase Flow in Complex Systems

Two-Phase Flow in Complex Systems PDF Author: Salomon Levy
Publisher: John Wiley & Sons
ISBN: 9780471329671
Category : Technology & Engineering
Languages : en
Pages : 450

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Book Description
Mehrphasige Strömungen spielen in etlichen Industriezweigen, besonders der Luft- und Raumfahrt und der Energieerzeugung, eine zentrale Rolle. Derart komplexe Strömungsvorgänge sind extrem schwer vorauszuberechnen, zu analysieren und zu testen. Wertvolle Hilfestellungen, die für reale technische Situationen gedacht sind, gibt dieser Band, der auch Quelltexte einschlägiger Computerprogramme enthält. (07/99)

Nuclear Science Abstracts

Nuclear Science Abstracts PDF Author:
Publisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 612

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Proceedings

Proceedings PDF Author: Gad Hetsroni
Publisher: Pergamon
ISBN: 9780080170350
Category : Heat
Languages : en
Pages : 766

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Convective Boiling and Condensation

Convective Boiling and Condensation PDF Author: John G. Collier
Publisher: Clarendon Press
ISBN: 0191591262
Category :
Languages : en
Pages : 646

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Book Description
* 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. -

Contribution to the Theory of Two-phase, One-component Critical Flow

Contribution to the Theory of Two-phase, One-component Critical Flow PDF Author: Hans K. Fauske
Publisher:
ISBN:
Category : Enthalpy
Languages : en
Pages : 354

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Book Description
Equipment was built where critical-flow data above 100 psia were obtained and a theory developed that predicts the experimental values satisfactorily. Theoretical expressions for the specific volume, void fraction, and slip ratio for critical steam-water mixtures have been derived. Therefore, the first complete analytical solution was made possible for estimating the critical two-phase flow rate, including slip between the two phases. The pressure profiles for runs at critical flow were all characterized by extremely steep pressure gradients near the throat; however, the pressure gradients are definitely finite and approach absolute maximum values, these depending only upon critical flow rate and quality. Sonic velocities are not achieved in critical two-phase flow of steam-water mixtures.

Annular Two-Phase Flow

Annular Two-Phase Flow PDF Author: Geoffrey Hewitt
Publisher: Elsevier
ISBN: 1483285235
Category : Technology & Engineering
Languages : en
Pages : 327

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Book Description
Annular Two-Phase Flow presents the wide range of industrial applications of annular two-phase flow regimes. This book discusses the fluid dynamics and heat transfer aspects of the flow pattern. Organized into 12 chapters, this book begins with an overview of the classification of the various types of interface distribution observed in practice. This text then examines the various regimes of two-phase flow with emphasis on the regions of occurrence of the annular flow regime. Other chapters consider the single momentum and energy balances, which illustrate the differences and analogies between single- and two-phase flows. This book discusses as well the simple modes for annular flow with consideration to the calculation of the profile of shear stress in the liquid film. The final chapter deals with the techniques that are developed for the measurement of flow pattern, entrainment, and film thickness. This book is a valuable resource for chemical engineers.

Two-phase, one component stratified flow with condensation

Two-phase, one component stratified flow with condensation PDF Author: Charles Eduard Rufer
Publisher:
ISBN:
Category :
Languages : en
Pages : 168

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Book Description


Phase Separation in Two-phase Microfluidic Heat Exchangers

Phase Separation in Two-phase Microfluidic Heat Exchangers PDF Author: Milnes P. David
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 151

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Book Description
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.