Discussion of paper ‘a theoretical solution of the lockhart and martinelli flow model for calculating two-phase flow pressure drop and hold-up’

1973 ◽  
Vol 16 (1) ◽  
pp. 225-226 ◽  
Author(s):  
D. Chisholm
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Theoretical Solution ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Pressure

Predicting Two Phase Flow Pressure Drop With CFD and ANN

2010 ◽  
Author(s):  
I˙smail Teke ◽  
O¨zden Ag˘ra ◽  
Hakan Demir ◽  
S¸. O¨zgu¨r Atayılmaz
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Saturation Temperature ◽  
Smooth Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Analytical Formulas ◽  
Flow Pressure ◽  
Good Agreement

In this study, the several well known two-phase viscosity models were used for predicting two-phase flow pressure drop in a smooth tube using Computational Fluid Dynamics (CFD) software at homogenous flow conditions. Pressure drop for two different mass flux values (300 and 650 kg/m2s) for R134a with a saturation temperature of 45 °C in a smooth tube has been modeled according to the homogenous flow model and the results have been compared with the analytical formulas and experimental data from the literature. Three different average viscosity correlations were used. It is seen that the numerical results are in a good agreement with the homogenous flow model and fall in ± 30% band. Also, the results derived from the average viscosity expression are in a good agreement with the results calculated using separated two-phase flow correlations. In addition to this, Artificial Neural Networks (ANNs) were employed for predicting the pressure drop in a horizontal smooth pipe. The trained network gives the best values over the correlations with less than 1% mean relative error.

scholarly journals Experimental Investigation and Prediction on Pressure Drop during Flow Boiling in Horizontal Microchannels

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 510
Author(s):  
Yan Huang ◽  
Bifen Shu ◽  
Shengnan Zhou ◽  
Qi Shi
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Separated Flow ◽  
Heat Fluxes ◽  
Phase Flow ◽  
Vapor Quality ◽  
Two Phase ◽  
Gas Flux

In this paper, two-phase pressure drop data were obtained for boiling in horizontal rectangular microchannels with a hydraulic diameter of 0.55 mm for R-134a over mass velocities from 790 to 1122, heat fluxes from 0 to 31.08 kW/m2 and vapor qualities from 0 to 0.25. The experimental results show that the Chisholm parameter in the separated flow model relies heavily on the vapor quality, especially in the low vapor quality region (from 0 to 0.1), where the two-phase flow pattern is mainly bubbly and slug flow. Then, the measured pressure drop data are compared with those from six separated flow models. Based on the comparison result, the superficial gas flux is introduced in this paper to consider the comprehensive influence of mass velocity and vapor quality on two-phase flow pressure drop, and a new equation for the Chisholm parameter in the separated flow model is proposed as a function of the superficial gas flux . The mean absolute error (MAE ) of the new flow correlation is 16.82%, which is significantly lower than the other correlations. Moreover, the applicability of the new expression has been verified by the experimental data in other literatures.

Evaluation Analysis of Prediction Methods for Two-Phase Flow Pressure Drop in Mini-Channels

2008 ◽  
Author(s):  
Licheng Sun ◽  
Kaichiro Mishima
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulent Region ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Mini Channels ◽  
Flow Pressure ◽  
Better Than

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.

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