scholarly journals Flow boiling of ammonia in vertical small diameter tubes: Two phase frictional pressure drop results and assessment of prediction methods

2012 ◽  
Vol 54 ◽  
pp. 1-12 ◽  
Author(s):  
M.H. Maqbool ◽  
B. Palm ◽  
R. Khodabandeh
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Small Diameter ◽  
Prediction Methods ◽  
Two Phase ◽  
Frictional Pressure Drop

Experimental Investigation of Flow Boiling Pressure Drop of R134A in a Microscale Horizontal Smooth Tube

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Cristiano Bigonha Tibiriçá ◽  
Jaqueline Diniz da Silva ◽  
Gherhardt Ribatski
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Flow Boiling ◽  
Smooth Tube ◽  
Working Fluid ◽  
Prediction Methods ◽  
Internal Diameter ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop

This paper presents new experimental flow boiling pressure drop results in a microscale tube. The experimental data were obtained under diabatic conditions in a horizontal smooth tube with an internal diameter of 2.32 mm. Experiments were performed with R134a as working fluid, mass velocities ranging from 100 kg/m2 s to 600 kg/m2 s, heat flux ranging from 10 kW/m2 to 55 kW/m2, saturation temperatures of 31°C, and exit vapor qualities from 0.20 to 0.99. Flow pattern characterization was also performed from images obtained by high-speed filming. Pressure drop gradients up to 48 kPa/m were measured. These data were carefully analyzed and compared against 13 two-phase frictional pressure drop prediction methods, including both macro- and microscale methods. Comparisons against these methods based on the data segregated according to flow patterns were also performed. Overall, the method by Cioncolini et al. (2009, “Unified Macro-to-Microscale Method to Predict Two-Phase Frictional Pressure Drops of Annular Flows,” Int. J. Multiphase Flow, 35, pp. 1138–1148) provided quite accurate predictions of the present database.

Flow boiling in horizontal flattened tubes: Part I – Two-phase frictional pressure drop results and model

2009 ◽  
Vol 52 (15-16) ◽  
pp. 3634-3644 ◽  
Author(s):  
Jesús Moreno Quibén ◽  
Lixin Cheng ◽  
Ricardo J. da Silva Lima ◽  
John R. Thome
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Two Phase ◽  
Frictional Pressure Drop

Experimental Adiabatic Two-Phase Pressure Drops of R134a, R236fa and R245fa in Small Horizontal Circular Channels

2011 ◽  
Author(s):  
Chin L. Ong ◽  
John R. Thome
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Prediction Methods ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range ◽  
Small Channels ◽  
Experimental Pressure ◽  
Phase Pressure

Experimental adiabatic two-phase pressure drops data for refrigerants R134a, R236fa and R245fa during flow boiling in small channels with internal diameters of 1.03, 2.20 and 3.04 mm are presented. The main purpose was to investigate the effects of channel confinement on adiabatic two-phase pressure drops. Thus, the two-phase pressure drop trends were systematically investigated over a wide range of test conditions for all three refrigerants and channel sizes. Statistical comparisons have also been made by comparing the experimental pressure drop data database with various macroscale and microscale prediction methods from the literature. The comparison showed relatively moderate accuracy for three prediction methods developed for macroscale flows, i.e. Baroczy and Chisholm, Friedel and the homogeneous model with the Cicchitti et al. viscosity relation. As for microscale prediction methods, the Cioncolini et al. annular flow model worked best with 68.5% of the data within ± 30%, followed by the Sun and Mishima and the Zhang et al. methods. Combining this database with the LTCM lab’s earlier database for 0.509 and 0.790 mm channels, there appears to be no evidence of a macro-to-microscale transition, at least with respect to two-phase pressure drops.

PRESSURE DROP CHARACTERISTICS OF R410A-OIL MIXTURE FLOW BOILING IN SMALL SMOOTH TUBES

2010 ◽  
Vol 18 (02) ◽  
pp. 109-116 ◽  
Author(s):  
YIFENG GAO ◽  
BIN DENG ◽  
GUOLIANG DING ◽  
HAITAO HU ◽  
XIANGCHAO HUANG
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Smooth Tube ◽  
Two Phase ◽  
Experimental Conditions ◽  
Mixture Flow ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Smooth Tubes ◽  
Local Properties

This study presents experimental frictional pressure drop for R410A/oil mixture flow boiling in small horizontal smooth tubes with inside diameters of 4.18 mm and 2.0 mm. Experimental conditions cover nominal oil concentrations from 0 to 5%. The test results show that the presence of oil enhances two-phase frictional pressure drop about 0–120% and 0–90% at present test conditions for 4.18 mm I.D. smooth tube and 2.0 mm I.D. smooth tube, respectively, and the enhanced effect is more evident at higher vapor qualities where the local oil concentrations are higher. A new correlation to predict the local frictional pressure drop of R410A/oil mixture flow boiling inside conventional size and small smooth tubes is developed based on local properties of refrigerant–oil mixture, and the experimental data of 4.18 mm I.D. and 2.0 mm I.D. smooth tubes and that of 6.34 mm I.D. smooth tube (Hu et al., 2008) are well-correlated with the new correlation.

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