A Mechanistic Model for Countercurrent Steam-Water Flow

1980 ◽  
Vol 102 (4) ◽  
pp. 688-693 ◽  
Author(s):  
A. Segev ◽  
R. P. Collier
Keyword(s):  
Liquid Film ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Heated Wall ◽  
Vapor Flow ◽  
Momentum Exchange ◽  
Test Parameters ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Liquid Film Flow

A one-dimensional model has been developed to describe the flow behavior of a liquid film draining down a heated wall, in the presence of countercurrent vapor flow. The effects of nonequilibrium void generation at the walls and condensation of countercurrent vapor on the penetrating liquid film interface, as well as on the bypassed liquid, have been considered. The momentum exchange is described by a correlation, assumed to apply at the entrance region, where the amount of liquid film flow is limited by the net vapor upflow. Theoretical predictions were compared with over 600 test results, obtained in 1/15- and 2/15-scale models of a PWR downcomer, over a wide range of test parameters. The comparisons exhibit a fairly good agreement.

Prediction of High Viscosity Liquid/Gas Two-Phase Slug Length in Horizontal and Slightly Inclined Pipelines

2021 ◽  
Author(s):  
Omar Shaaban ◽  
Eissa Al-Safran
Keyword(s):  
Numerical Optimization ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
High Viscosity ◽  
Oil Well ◽  
Liquid Slug ◽  
Two Phase ◽  
Proposed Model ◽  
Wide Range ◽  
Flow Closure

Abstract The production and transportation of high viscosity liquid/gas two-phase along petroleum production system is a challenging operation due to the lack of understanding the flow behavior and characteristics. In particular, accurate prediction of two-phase slug length in pipes is crucial to efficiently operate and safely design oil well and separation facilities. The objective of this study is to develop a mechanistic model to predict high viscosity liquid slug length in pipelines and to optimize the proper set of closure relationships required to ensure high accuracy prediction. A large high viscosity liquid slug length database is collected and presented in this study, against which the proposed model is validated and compared with other models. A mechanistic slug length model is derived based on the first principles of mass and momentum balances over a two-phase slug unit, which requires a set of closure relationships of other slug characteristics. To select the proper set of closure relationships, a numerical optimization is carried out using a large slug length dataset to minimize the prediction error. Thousands of combinations of various slug flow closure relationships were evaluated to identify the most appropriate relationships for the proposed slug length model under high viscosity slug length condition. Results show that the proposed slug length mechanistic model is applicable for a wide range of liquid viscosities and is sensitive to the selected closure relationships. Results revealed that the optimum closure relationships combination is Archibong-Eso et al. (2018) for slug frequency, Malnes (1983) for slug liquid holdup, Jeyachandra et al. (2012) for drift velocity, and Nicklin et al. (1962) for the distribution coefficient. Using the above set of closure relationships, model validation yields 37.8% absolute average percent error, outperforming all existing slug length models.

An Investigation of the Liquid Distribution in Annular-Mist Flow

1970 ◽  
Vol 92 (4) ◽  
pp. 651-658 ◽  
Author(s):  
J. T. Pogson ◽  
J. H. Roberts ◽  
P. J. Waibler
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Droplet Size Distribution ◽  
Correlation Equation ◽  
Vapor Flow ◽  
Two Phase ◽  
Liquid Distribution ◽  
Liquid Film Flow

The results of an experimental investigation of the average liquid film thickness are presented for vertical upward annular-mist two-phase flow, with and without heat transfer. The effects on the film thickness for variations in vapor flow rate, liquid flow rate, vapor density, and heat transfer are described. A correlation equation is presented for the local time-averaged thickness and for the droplet size distribution. In addition, an equation is given for the liquid film flow rate as a function of the average film thickness.

CFD Modeling of a Thin Liquid Film Flow over Horizontal Spinning Disk

2014 ◽  
Vol 625 ◽  
pp. 517-521
Author(s):  
Nurhazwani Yusoff Azudin ◽  
Mohd Fadhil Majnis ◽  
Ahmad Abdul Latif ◽  
Syamsul Rizal Abd Shukor
Keyword(s):  
Liquid Film ◽  
Cfd Simulation ◽  
Film Flow ◽  
Mechanistic Model ◽  
Thin Liquid Film ◽  
Process Intensification ◽  
Cfd Modeling ◽  
Spinning Disk ◽  
Vof Model ◽  
Liquid Film Flow

A thin liquid film flow over horizontal spinning disk under influence of centrifugal field is one of the implementation and method in process intensification. Hydrodynamic studies and development of mechanistic model is desired to describe this film flow behaviours. CFD software package, Fluent® 6.3 was used to simulate a multiphase volume of fraction (VOF) model of this flow. Then, experiments were carried out in a spinning disk test rig with variable speed of spinning and results were compared with CFD simulation. The result obtained have showed that CFD model for thin liquid film thickness was in satisfactory agreement with the experimental results with R2 = 0.841 to 0.857.

On the Liquid Film Flow Characteristics During the Rewetting in the Single Rod Air-Water System

2018 ◽  
Author(s):  
Yuki Wada ◽  
Dan Le ◽  
Akira Satou ◽  
Yasuteru Sibamoto ◽  
Taisuke Yonomoto
Keyword(s):  
Liquid Film ◽  
Film Flow ◽  
Current System ◽  
Mechanistic Model ◽  
Water System ◽  
Flow Characteristics ◽  
Liquid Film Flow ◽  
Single Heater ◽  
Dry Out ◽  
Cooling Model

Dry-out and rewetting phenomenon may occur on a fuel rod surface during anticipated operational occurrences (AOOs) for a boiling water reactor (BWR). The conventional rewetting model included in the current system code tends to underestimate the rewetting propagation velocity due to the absence of an appropriate precursory cooling model. The present research aims at the development of a mechanistic model for the precursory cooling in the annular mist flow regime typical of AOO and anticipated transition without scrum (ATWS). Rewetting experiments were carried out using a single heater rod in the circular glass pipe with air-water flow at atmospheric pressure to visualize the rewetting behavior and obtain mechanistic understanding on the phenomena. This paper summarizes the experimental results and discusses the liquid film flow characteristics including roll wave formation and spattering at the rewetting front.

scholarly journals Numerical Visualization of Heated Liquid Film Flow Behavior around a Spacer in a Narrow Channel

2005 ◽  
Vol 25 (Supplement2) ◽  
pp. 369-370
Author(s):  
Etsuo KUME ◽  
Tatsuaki KITAMURA ◽  
Kazuyuki TAKASE ◽  
Yasuo OSE
Keyword(s):  
Liquid Film ◽  
Film Flow ◽  
Flow Behavior ◽  
Narrow Channel ◽  
Numerical Visualization ◽  
Liquid Film Flow

G505 Effect of Curved Fuel Rods on Liquid Film Flow Behavior(1)

2006 ◽  
Vol 2006 (0) ◽  
pp. _G505-a_
Author(s):  
Kazuyuki Takase ◽  
Hiroyuki Yoshida ◽  
Mitsuhiko Shibata ◽  
Tatsuaki Kitamura ◽  
Etsuo Kume ◽  
...  
Keyword(s):  
Liquid Film ◽  
Film Flow ◽  
Flow Behavior ◽  
Fuel Rods ◽  
Liquid Film Flow

scholarly journals NATURAL CONVECTION IN RECTANGULAR CAVITIES WITH DIFFERENT ASPECT RATIOS

2011 ◽  
Vol 10 (1-2) ◽  
pp. 44
Author(s):  
R. M. Nogueira ◽  
M. A. Martins ◽  
F. Ampessan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Flow Behavior ◽  
Heated Wall ◽  
Flow Profile ◽  
Height Ratio ◽  
Dimensionless Variable ◽  
Aspect Ratios ◽  
Wide Range

Natural convection in closed cavities has been extensively studied in recent decades. This spontaneous method of heat transfer has a wide range of applications in engineering. In the present work, natural convection was numerically analyzed in a rectangular cavity heated on one of the sides and cooled on the opposite side. Temperatures of the heated wall and of the cooled wall were assumed to be constant. The objective of these studies was to determine the effects of the aspect ratio and the Rayleigh number on flow behavior and heat transfer in the cavity. In the simulations, the Rayleigh number drastically influenced the flow profile and heat transfer inside de cavity, as well as the thickness of the thermal boundary layer. It was also verified that the Nusselt number is strongly dependent on the L/D (Length/Height) ratio, and that this dimensionless variable increases with the increase of the W/L. The simulation of natural convection problems in the CFD Studio satisfactorily described the studied situations.

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