Entropy Production, Friction Factors, and Holdup in Particulate Two-Phase Flow in Pipes

2007 ◽  
Vol 32 (2) ◽  
Author(s):  
Efstathios E Michaelides ◽  
Emmanuel A Michaelides
Keyword(s):  
Entropy Production ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Friction Factors

scholarly journals Experimental Determination of Friction Factors in Two Phase Flow Through a Porous Medium

2015 ◽  
Vol 8 (3) ◽  
Author(s):  
Ruizhe Cheng
Keyword(s):  
Porous Medium ◽  
Pressure Gradient ◽  
Two Phase Flow ◽  
Severe Accident ◽  
Phase Flow ◽  
Two Phase ◽  
Safety Mechanism ◽  
Friction Factors ◽  
Flow Through

In a severe accident, the decay heat from the fuel located in the calandria may boil the water circulated through the end shields of a CANDU reactor, causing a two phase flow of water and steam. This two phase mixture may interfere with heat transport if a thin film of steam forms on the inside surface of the end shields. As water and steam run through the end shields, frictional energy loss results in a pressure gradient. The pressure gradient is directly related to the velocity of the fluid, which can be inferred from the permeability of the end shield. Therefore, this project serves to determine the friction factors that cause pressure drop in the end shields of a CANDU Reactor and aims to examine the safety mechanism of the existing end shields. The results of this project corroborated the Gibilaro equation for one phase flow and implied the lack of proper handling of important friction factors in equations for two phase flow. Therefore, further studies on two phase flow through porous medium are needed.

Simulation of Transient Two-Phase Flow in Pipelines

1986 ◽  
Vol 108 (3) ◽  
pp. 202-206 ◽  
Author(s):  
Y. Sharma ◽  
M. W. Scoggins ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Empirical Correlations ◽  
Liquid Holdup ◽  
System Of Difference Equations ◽  
Two Phase ◽  
Wet Gas ◽  
Friction Factors ◽  
Sequential Solution ◽  
Implicit Finite Difference

The laws of conservation of mass and linear momentum were applied to a two-phase mixture to formulate a mathematical model which simulates isothermal, transient two-phase flow of gas and liquid in a pipeline. Liquid holdup and friction factors were incorporated via existing empirical correlations, and the black oil method was used to describe interphase mass transfer. Implicit finite difference analogues were derived for the nonlinear set of partial differential equations which constituted the basis of the model. The system of difference equations was solved using a sequential solution algorithm implementing a Newton-Raphson iterative procedure. The numerical model formulated was used to predict the performance of an existing wet gas pipeline to establish the validity of the model. Example simulation runs were used to provide insights into the nature of transient two-phase flow.

Single-Phase and Two-Phase Flow Pressure Drop in a Long Double Helicoidally-Coiled Tube

2021 ◽  
Author(s):  
Veera Manek ◽  
Tao Fang ◽  
S. Mostafa Ghiaasiaan ◽  
Jeff Patelczyk
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Single Phase ◽  
Two Phase Flow ◽  
Reynolds Numbers ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Friction Factors ◽  
Flow Experiments

Abstract Single-phase and two-phase frictional pressure drop in horizontally-oriented double helically coiled tubes confined in a cylindrical shell is experimentally studied using an instrumented test loop that represents a prototypical liquified natural gas (LNG) fuel delivery system for internal combustion (IC) engines. Adiabatic experimental data addressing liquid (water) and gas (nitrogen) single-phase flows, as well as two-phase flows (air-water) in the helicoidally coiled tubes are presented. The range of Reynolds numbers for single-phase flow experiments is 2600 to 4800. In two-phase flow experiments the liquid-only and gas-only Reynolds numbers varied in 1030 to 6600 and 1700 to 17700 ranges, respectively. In laminar single-phase flow regime the measured friction factors are in relatively good agreement with well-established correlations. In the turbulent flow regime the measured friction factors are moderately higher than the prediction of well-established published correlations. Two-phase flow frictional pressure drops are compared with some relevant correlations, with poor agreement. The generated experimental data are empirically correlated based on the two-phase flow multiplier concept.

Estimation of Steady-State Steam Void-Fraction by Means of the Principle of Minimum Entropy Production

1964 ◽  
Vol 86 (2) ◽  
pp. 247-251 ◽  
Author(s):  
S. M. Zivi
Keyword(s):  
Steady State ◽  
Entropy Production ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Wall Friction ◽  
Phase Flow ◽  
Minimum Entropy ◽  
Two Phase ◽  
Slip Ratio ◽  
State Process

An analysis of steam-void fraction in two-phase flow is carried out, utilizing the principle that in a steady-state thermodynamic process the rate of entropy production is minimum. The two-phase flow is idealized in the analysis to be a truly steady-state process. The effects of liquid entrainment and wall friction on the void fraction and slip ratio are evaluated. It is found that the slip-ratio in an idealized two-phase flow with zero wall friction and zero entrainment equals (ρf/ρg)1/3. Data from a number of experiments are found to be bracketed between this result and the result obtained by assuming complete entrainment (slip ratio = 1).

Sign in / Sign up

Export Citation Format

Share Document