An Experimental and Theoretical Study of Transient Pressure Drop in Two-Phase Condensing Flows

1989 ◽  
Vol 111 (2) ◽  
pp. 546-551 ◽  
Author(s):  
G. L. Wedekind ◽  
B. L. Bhatt ◽  
G. L. Roslund
Keyword(s):  
Pressure Drop ◽  
Horizontal Tube ◽  
Analytical Prediction ◽  
Transient Pressure ◽  
Two Phase ◽  
Type Change ◽  
Condensing Flows ◽  
Similarity Relationships ◽  
Tube Condenser ◽  
Good Agreement

This paper presents the results of an experimental and theoretical investigation of the pressure drop associated with transient two-phase condensing flows involving complete condensation. Utilizing the system mean void fraction model, and the similarity relationships associated with it, an analytical prediction of the transient pressure drop is possible, including a simplified closed-form version. The capability of the proposed theory is demonstrated by comparison with experimental measurements of the transient pressure drop in a horizontal tube condenser following an exponential-type change in the inlet mass flow rate. Good agreement is shown to exist between the predicted and experimental results.

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

INVESTIGATION ON VOID FRACTION FOR TWO-PHASE FLOW PRESSURE DROP OF EVAPORATIVE R-290 IN HORIZONTAL TUBE

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Agus Sunjarianto Pamitran ◽  
Sentot Novianto ◽  
Normah Mohd-Ghazali ◽  
Nasruddin Nasruddin ◽  
Raldi Koestoer
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Conditions

Two-phase flow boiling pressure drop experiment was conducted to observe its characteristics and to develop a new correlation of void fraction based on the separated model. Investigation is completed on the natural refrigerant R-290 (propane) in a horizontal circular tube with a 7.6 mm inner diameter under experimental conditions of 3.7 to 9.6 °C saturation temperature, 10 to 25 kW/m2 heat flux, and 185 to 445 kg/m2s mass flux. The present experimental data was used to obtain the calculated void fraction which then was compared to the predicted void fraction with 31 existing correlations. A new void fraction correlation for predicting two-phase flow boiling pressure drop, as a function of Reynolds numbers, was proposed. The measured pressure drop was compared to the predicted pressure drop with some existing pressure drop models that use the newly developed void fraction model. The homogeneous model of void fraction showed the best prediction with 2% deviation

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 on two-phase frictional pressure drop of zeotropic mixtures of R50/R170 in a horizontal tube

2017 ◽  
Vol 63 (4) ◽  
pp. 471-480
Author(s):  
Xin Zou ◽  
Qinglu Song ◽  
Zhiqiang Yang ◽  
Qixiong Tang ◽  
Xiaoru Zhuang ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Horizontal Tube ◽  
Two Phase ◽  
Frictional Pressure Drop

scholarly journals Heat Transfer and Pressure Drop Characteristics During R22 Evaporation in an Oval Microfin Tube

2000 ◽  
Vol 123 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Man-Hoe Kim ◽  
Jeong-Seob Shin ◽  
Clark W. Bullard
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Horizontal Tube ◽  
Outer Diameter ◽  
Transfer Coefficients ◽  
Round Tube ◽  
Two Phase ◽  
Axis Ratio ◽  
Oval Tube ◽  
Microfin Tubes

An experimental study on R22 evaporating heat transfer in round and oval microfin tubes has been performed. The oval tube was an elliptic tube of axis ratio 1:1.5, which was fabricated from the round tube with an outer diameter of 9.52 mm and 18 deg helix angle counterclockwise. The test section was a straight horizontal tube of 0.6 m in length and was heated electrically by a tape heater wound on the tube surface. Heat flux of 12 kW/m2 was maintained constant and the range of refrigerant quality was 0.2–0.8. The tests were conducted for evaporation at 15 °C for 30–60 kg/h mass flow rate (mass flux based on the oval tube: 150–300 kg/m2s) and the installation angles of the oval tube were varied between 0 and 135 deg in the circumferential direction. The local and average heat transfer and pressure drop characteristics for the oval tube were compared to those for the baseline round tube. The average two-phase heat transfer coefficients for the oval tube were 2–12 percent higher than that for the round tube and pressure drops for both tubes are similar. The single heat transfer coefficient and friction factor correlations for the round and oval microfin tubes are developed within the rms errors of ±5.6 percent and ±10.0 percent, respectively.

scholarly journals Two-phase frictional pressure drop of 1,1-difluoroethane in a horizontal tube

2010 ◽  
Vol 59 (12) ◽  
pp. 8669
Author(s):  
Chen Gao-Fei ◽  
Gong Mao-Qiong ◽  
Shen Jun ◽  
Zou Xin ◽  
Wu Jian-Feng
Keyword(s):  
Pressure Drop ◽  
Horizontal Tube ◽  
Two Phase ◽  
Frictional Pressure Drop
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