Droplet Entrainment Correlation for High Pressure Annular Two-phase Flow PDF Download
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ISBN:
Category :
Languages : en
Pages : 25
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Book Description
The amount of entrainment in annular flow is essential to predict the point of dryout. Most of the entrainment correlations available in the literature are obtained from air-water low pressure data. However many important industrial applications involve high pressure annular flows. There are very few correlations applicable in this range and they are solely based on empirical data fits. Comparing the low pressure entrainment data of Cousins and Hewitt (1968) and the high pressure data of Keeys et. al. (1970) and Wurtz (1978) with existing correlations, the agreement at high pressure is generally poor, except for the empirical correlation of Nigmatulin and Krushenok (1989) which depends on a Weber number that includes the droplet concentration. We propose a new semi-mechanistic entrainment correlation for fully developed annular flow conditions: E = (0.9642)/(1 + (3836/We{sub C})). It is developed based on the droplet continuity equation and the entrainment rate model of Dallman et. al. (1979). This model is then modified to introduce a Weber number that includes the droplet concentration, We{sub C}. This Weber number is shown to scale the available high and low pressure air-water and steam-water data better than the other definitions. Because the new correlation is based on a model of entrainment rate it may be used as a starting point in the development of a correlation for this process applicable to high pressure water-steam annular flows. A correlation is suggested pending validation with high pressure entrainment rate data. 12 refs., 11 figs.
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ISBN:
Category :
Languages : en
Pages : 25
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Book Description
The amount of entrainment in annular flow is essential to predict the point of dryout. Most of the entrainment correlations available in the literature are obtained from air-water low pressure data. However many important industrial applications involve high pressure annular flows. There are very few correlations applicable in this range and they are solely based on empirical data fits. Comparing the low pressure entrainment data of Cousins and Hewitt (1968) and the high pressure data of Keeys et. al. (1970) and Wurtz (1978) with existing correlations, the agreement at high pressure is generally poor, except for the empirical correlation of Nigmatulin and Krushenok (1989) which depends on a Weber number that includes the droplet concentration. We propose a new semi-mechanistic entrainment correlation for fully developed annular flow conditions: E = (0.9642)/(1 + (3836/We{sub C})). It is developed based on the droplet continuity equation and the entrainment rate model of Dallman et. al. (1979). This model is then modified to introduce a Weber number that includes the droplet concentration, We{sub C}. This Weber number is shown to scale the available high and low pressure air-water and steam-water data better than the other definitions. Because the new correlation is based on a model of entrainment rate it may be used as a starting point in the development of a correlation for this process applicable to high pressure water-steam annular flows. A correlation is suggested pending validation with high pressure entrainment rate data. 12 refs., 11 figs.
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.
Author: Isao Kataoka
Publisher:
ISBN:
Category : Two-phase flow
Languages : en
Pages : 64
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Author:
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ISBN:
Category :
Languages : en
Pages : 36
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The droplet entrainment from a liquid film by gas flow is important to mass, momentum, and energy transfer in annular two-phase flow. The amount of entrainment can significantly affect occurrences of the dryout and post-dryout heat flux as well as the rewetting phenomena of a hot dry surface. In view of these, a correlation for the amount of entrained liquid in annular flow has been developed from a simple model and experimental data. There are basically two different regions of entrainment, namely, the entrance and quasiequilibrium regions. The correlation for the equilibrium region is expressed in terms of the dimensionless gas flux, diameter, and total liquid Reynolds number. The entrance effect is taken into account by an exponential relaxation function. It has been shown that this new model can satisfactorily correlate wide ranges of experimental data for water. Furthermore, the necessary distance for the development of entrainment is identified. These correlations, therefore, can supply accurate information on entrainment which have not been available previously. (author).
![Entrainment and Deposition Rates of Droplets in Annular Two-phase Flow. [PWR ; BWR]. PDF](https://books.google.com/books/content/images/frontcover/jw9yAQAACAAJ?fife=w80-h100)
Author:
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Category :
Languages : en
Pages :
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Book Description
The droplet entrainment from a liquid film is important to the mass, momentum, and energy transfer processes in annular two-phase flow. For example, the amount of entrainment as well as the rate of entrainment significantly affect the occurrences of the dryout, whereas the post CHF heat transfer depends strongly on the entrainment and droplet sizes. Despite the importance of the entrainment rate, there have been no satisfactory correlations available in the literature. In view of these, correlations for entrainment rate covering both entrance region and equilibrium region have been developed from a simple model in collaboration with data. Results show that the entrainment rate varies considerably in the entrainment development region, however, at a certain distance from an inlet it attains an equilibrium value. A simple approximate correlation has been obtained for the equilibrium state where entrainment rate and deposition rate becomes equal. The result indicates that the equilibrium entrainment rate is proportional to Weber number based on the hydraulic diameter of a tube.
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ISBN:
Category :
Languages : en
Pages :
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Book Description
The droplet entrainment from a liquid film by gas flow is important to mass, momentum, and energy transfer in annular two-phase flow. The amount of entrainment can significantly affect occurrences of the dryout and post-dryout heat flux as well as the rewetting phenomena of a hot dry surface. In view of these, a correlation for the amount of entrained liquid in annular flow has been developed from a simple model and experimental data. There are basically two different regions of entrainment, namely, the entrance and quasiequilibrium regions. The correlation for the equilibrium region is expressed in terms of the dimensionless gas flux, diameter, and total liquid Reynolds number. The entrance effect is taken into account by an exponential relaxation function. It has been shown that this new model can satisfactorily correlate wide ranges of experimental data for water. Furthermore, the necessary distance for the development of entrainment is identified. These correlations, therefore, can supply accurate information on entrainment which have not been available previously. (author).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
Air/water and vapor/freon were utilized to scale and simulate annular two-phase flow for high pressure steam/water conditions. A unique vapor/liquid Freon loop was built to obtain the high pressure data. The results were compared with two correlations available in the open literature. The Ishii and Mishima dimensionless group was able to scale the data remarkably well even for vapor/liquid Freon. However, the correlation needs to be adjusted for high Weber numbers of the gas phase.
Author: Volfango Bertola
Publisher: CISM International Centre for Mechanical Sciences
ISBN:
Category : Science
Languages : en
Pages : 450
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Book Description
This is an up-to-date review of recent advances in the study of two-phase flows, with focus on gas-liquid flows, liquid-liquid flows, and particle transport in turbulent flows. The book is divided into several chapters, which after introducing basic concepts lead the reader through a more complex treatment of the subjects. The reader will find an extensive review of both the older and the more recent literature, with abundance of formulas, correlations, graphs and tables. A comprehensive (though non exhaustive) list of bibliographic references is provided at the end of each chapter. The volume is especially indicated for researchers who would like to carry out experimental, theoretical or computational work on two-phase flows, as well as for professionals who wish to learn more about this topic.
Author: Kim Ann Shollenberger
Publisher:
ISBN:
Category :
Languages : en
Pages : 292
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Author: Henry Aloysius Putre
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 242
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Book Description
