Measurement and Correlation of Frictional Pressure Drop of R-410A/Oil Mixture Flow Boiling in a 7 mm Straight Smooth Tube

2008 ◽  
Vol 14 (5) ◽  
pp. 763-781 ◽  
Author(s):  
Haitao Hu ◽  
Guoliang Ding ◽  
Wenjian Wei ◽  
Zhence Wang ◽  
Kaijian Wang
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Smooth Tube ◽  
Mixture Flow ◽  
Frictional Pressure Drop

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.

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.

Experimental Investigation of Flow Boiling Pressure Drop of R134a in a Micro-Scale Horizontal Smooth Tube

2010 ◽  
Author(s):  
Cristiano Bigonha Tibiric¸a´ ◽  
Gherhardt Ribatski
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Flow Boiling ◽  
Smooth Tube ◽  
Working Fluid ◽  
Internal Diameter ◽  
Two Phase ◽  
Pressure Drops ◽  
Micro Scale ◽  
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 internal diameter of 2.3 mm. Experiments were performed with R134a as working fluid, mass velocities ranging from 100 to 600 kg/m2s, heat flux ranging from 10 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 drops 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 micro-scale methods. Comparisons against these methods based on the data segregated according to flow patterns were also performed. Overall, the method by Cioncolini et al. [1] provided quite accurate predictions of the present database.

Augmented Performance of Flow Boiling Heat Transfer in a Tube With Axial Micro-Grooves and its Augmentation Mechanisms

1999 ◽  
Author(s):  
Lixin Cheng ◽  
Tingkuan Chen
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Axial Direction ◽  
Smooth Tube ◽  
Absolute Pressure ◽  
Transfer Coefficients ◽  
Frictional Pressure Drop ◽  
Flow Boiling Heat Transfer ◽  
Enhanced Tube

Abstract Experiments of upward flow boiling heat transfer with water in a vertical smooth tube and a tube with axial micro-grooves were respectively conducted. Both of the tested tubes have a length of 2.5 m, an inner diameter of 15 mm and an outlet diameter of 19 mm. The tube with axial micro grooves has many micro rectangle grooves in its inner wall along the axial direction. The grooves have a depth of 0.5 mm and a width of 0.3 mm. The tests were performed at an absolute pressure of 6 bar. The heat flux ranged from 0 to 550 kW/m2 and the mass flux was selected at 410, 610 and 810 kg/m2s, respectively. By comparison, flow boiling heat transfer coefficients in the enhanced tube are 1.6 ∼ 2.7 fold that in the smooth tube while the frictional pressure drop in the enhanced tube is slightly greater than that in the smooth tube. The augmentation of flow boiling heat transfer in the tube with axial micro-grooves is apparent. Based on the experimental data, a correlation of flow boiling heat transfer is proposed for the enhanced tube. Finally, the mechanisms of heat transfer enhancement are analyzed.

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