Benchmark of Delayed Equilibrium Model (DEM) and classic two-phase critical flow models against experimental data

2017 ◽  
Vol 92 ◽  
pp. 112-130 ◽  
Author(s):  
M. De Lorenzo ◽  
Ph. Lafon ◽  
J.-M. Seynhaeve ◽  
Y. Bartosiewicz
Keyword(s):  
Experimental Data ◽  
Equilibrium Model ◽  
Critical Flow ◽  
Two Phase ◽  
Flow Models

Analysis of two phase critical flow with a non-equilibrium model

2021 ◽  
Vol 372 ◽  
pp. 110998
Author(s):  
Hong Xu ◽  
Aurelian Florin Badea ◽  
Xu Cheng
Keyword(s):  
Equilibrium Model ◽  
Critical Flow ◽  
Two Phase ◽  
Non Equilibrium

scholarly journals Validation of NEPTUNE-CFD Two-Phase Flow Models Using Experimental Data

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Jorge Pérez Mañes ◽  
Victor Hugo Sánchez Espinoza ◽  
Sergio Chiva Vicent ◽  
Michael Böttcher ◽  
Robert Stieglitz
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Model Parameters ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Flow Models ◽  
Phase Models ◽  
Good Agreement

This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNEC-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too.

Assessment of Two Phase Critical Flow Models and Implementation in Fast Transient Fluid Dynamics Software

2015 ◽  
Author(s):  
Philippe Lafon ◽  
Mohamed Essadki ◽  
Yann Bartosiewicz ◽  
Jean-Marie Seynhaeve
Keyword(s):  
Critical Flow ◽  
Vapor Mixture ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Moby Dick ◽  
Flow Models ◽  
High Temperature And Pressure ◽  
Temperature And Pressure ◽  
Fast Transient ◽  
Dem Model

The discharge of a subcooled liquid or a liquid-vapor mixture at high temperature and pressure can occur in many industrial situations. This paper is focused on the analysis of critical flow models that are already available in the fast transient dynamics software EUROPLEXUS, or that are being implemented as new break boundary conditions. The results of the Moody, Fauske, Flinta, Henry-Fauske and DEM models are presented and compared with the Super Moby Dick experimental results. The best results are obtained for the DEM. Then preliminary results concerning the implementation of the DEM model as a break boundary condition in EUROPLEXUS are given.

Performance of Two-Phase Flow Models on the Prediction of Oscillatory Flow Conditions

2016 ◽  
Author(s):  
Catalina Posada ◽  
Paulo Waltrich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Pressure Gradient ◽  
Two Phase Flow ◽  
Percentage Error ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Models ◽  
Absolute Percentage Error

The present investigation presents a comparative study between two-phase flow models and experimental data. Experimental data was obtained using a 42 m long, 0.05 m ID tube system. The experimental data include conditions for pressures ranging from 1.2 to 2.8 bara, superficial liquid velocities 0.02–0.3 m/s, and superficial gas velocity ranges 0.17–26 m/s. The experimental data was used to evaluate the performance of steady-state empirical and mechanistic models while estimating liquid holdup and pressure gradient under steady-state and oscillatory conditions. The purpose of this analysis is first to evaluate the accuracy of the models predicting the liquid holdup and pressure gradient under steady-state conditions. Then, after evaluating the models under state-steady conditions, the same models are used to predict the same parameters for oscillatory and periodic conditions for similar gas and liquid velocities. The transient multiphase flow simulator OLGA, which has been widely used in the oil and gas industry, was implemented to model one oscillatory case to evaluate the prediction improvement while using a transient instead of a steady-state model to predict oscillatory flows. For the model with best performance for steady-state pressure gradient prediction, the absolute percentage error is 12% for Uls = 0.02 m/s and 5% for Uls = 0.3. For oscillatory conditions, the absolute percentage error is 30% for Uls = 0.02 m/s and 4% for Uls = 0.3. OLGA results underpredict the experimental pressure gradient under oscillatory conditions with errors up to 30%. Therefore, it was possible to conclude that the models can predict the average of the oscillatory data almost as well as for steady-state conditions.

A Review of Prediction Methods for Two-Phase Pressure Loss in Mini/Micro-Channels

2016 ◽  
Vol 24 (01) ◽  
pp. 1630002 ◽  
Author(s):  
Jung Hoon Yun ◽  
Ji Hwan Jeong
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Separated Flow ◽  
Empirical Correlations ◽  
Two Phase ◽  
Flow Models ◽  
Micro Channels ◽  
Extensive Experimental Data ◽  
Phase Pressure

Previous methods and correlations for predicting two-phase frictional pressure loss in mini/micro-channels are reviewed and compared. The empirical correlations are classified into four groups of modeling approaches: Homogeneous equilibrium models (HEMs), separated flow models (SFMs), direct empirical correlations, and flow pattern specific correlations. In order to examine the characteristics of the predictive methods for two-phase pressure loss in mini-channels and to assess the accuracy of the previous models and correlations, extensive experimental data and correlations that are available in the open literature are collected. The 1175 and 1304 experimental data for the two-phase pressure drop for condensing and boiling flows, respectively, are gathered from 15 papers and reports. The results present that the size of the channel significantly influences the pressure drop. The comparison demonstrates that Cicchitti et al.’s two-phase viscosity model is recommended for predicting two-phase pressure loss when the HEM is used. In general, the SFM with the two-phase multipliers of Muller–Steinhagen and Heck and Kim and Mudawar outperforms others for channel diameters of less than 3[Formula: see text]mm.

Two-Phase Critical Flow under Diabatic Conditions

1969 ◽  
Vol 184 (3) ◽  
pp. 127-133
Author(s):  
A. E. Bergles ◽  
J. T. Kelly
Keyword(s):  
Experimental Investigation ◽  
Equilibrium Model ◽  
Small Diameter ◽  
Critical Flow ◽  
Subcooled Boiling ◽  
Flow Conditions ◽  
Two Phase ◽  
Wide Range ◽  
Good Agreement ◽  
Non Equilibrium

This paper summarizes an experimental investigation of steam-water critical flow in heated tubes. A wide range of data was taken for water at pressures below 100 lbf/in2 (abs.) in tubes of small diameter. It is demonstrated that critical flow conditions can occur in subcooled boiling at low exit subcoolings. At equilibrium qualities below about 0·04, the data differ significantly from adiabatic data for a similar exit geometry. The deviations can be explained in terms of the additional non-equilibrium effects present in heated flows. For higher qualities, the diabatic data are in good agreement with adiabatic data, and can be approximately predicted by a slip equilibrium model.

Mach Number Scaling of Single-Component, Two-Phase Flow

1993 ◽  
Vol 115 (4) ◽  
pp. 772-777
Author(s):  
D. E. Nikitopoulos
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Critical Mass ◽  
Critical Flow ◽  
Phase Flow ◽  
Homogeneous State ◽  
Two Phase ◽  
Good Agreement

A simple two-fluid formulation is used to investigate compressibility effects and Mach number scaling for equilibrium, evaporating two-phase flow. The definition of the local two-phase Mach number emerges from a critical flow analysis. Comparisons of the theoretical critical mass flux with existing experimental data obtained in steam-water flows show very good agreement for moderate and high qualities over a wide critical pressure range. Within this quality range the predicted critical mass flux is quite insensitive to the velocity ratio. The analysis confirms previous observations, based on homogeneous flow models, indicating that in variable area ducts the critical state does not occur at a geometrical throat. Results of existing critical flow experiments in slowly diverging ducts are discussed in the light of this conclusion. A way from the neighborhood of the flash horizon, pressure-drop and kinetic energy changes are shown to scale with similar local Mach functions as those of single-phase compressible flow. Existing experimental data from vertical-upwards and horizontal two-phase flows in pipes indicate that the Mach number calculated on the basis of the local homogeneous state provides the optimum scaling performance. Scaling of the same experimental data using a Mach number based on the local nonhomogeneous state provides results that are in reasonably good agreement with the theoretical scaling guidelines and predictions, but is handicapped by considerable scatter in the scaled experimental variables.

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