An Experimental Investigation on Flow Boiling of Ethylene-Glycol/Water Mixtures

2003 ◽  
Vol 125 (2) ◽  
pp. 317-325 ◽  
Author(s):  
Satish G. Kandlikar ◽  
Murat Bulut
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Binary Mixtures ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Saturation Temperature ◽  
Local Heat Transfer ◽  
Transfer Coefficients ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

Mixtures of ethylene glycol and water are used in cooling the engines in automotive applications. Heat is transferred essentially under subcooled flow boiling conditions as the mixture flows over the hot surfaces, which are at temperatures well above the local saturation temperature of the mixture. Very little information is available in the literature on the subcooled flow boiling characteristics of this mixture. The present work focuses on obtaining experimental heat transfer data for water and its mixtures containing ethylene-glycol (0 to 40 percent mass fraction, limited by the maximum allowable temperature in the present setup) in the subcooled flow boiling region. The experimental setup is designed to obtain local heat transfer coefficients over a small circular aluminum heater surface, 9.5-mm in diameter, placed at the bottom 40-mm wide wall of a rectangular channel 3-mm×40-mm in cross-section. Available models for (a) subcooled flow boiling of pure liquids and (b) saturated flow boiling of binary mixtures are extended to model the subcooled flow boiling of binary mixtures.

Evaporation of Ammonia in a Smooth Horizontal Tube: Heat Transfer Measurements and Predictions

1999 ◽  
Vol 121 (1) ◽  
pp. 89-101 ◽  
Author(s):  
O. Zu¨rcher ◽  
J. R. Thome ◽  
D. Favrat
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Saturation Temperature ◽  
Local Heat Transfer ◽  
Horizontal Tube ◽  
Steel Tube ◽  
Heat Fluxes ◽  
Stainless Steel Tube ◽  
Transfer Coefficients ◽  
Two Phase

Experimental test results for flow boiling of pure ammonia inside horizontal tubes were obtained for a plain stainless steel tube. Tests were run at a nominal saturation temperature of 4°C, nine mass velocities from 20–140 kg/m2 s, vapor qualities from 1–99 percent and heat fluxes from 5–58 kW/m2. Two-phase flow observations showed that the current test data covered the following regimes: fully stratified, stratified-wavy, intermittent, annular, and annular with partial dryout. The Kattan-Thome-Favrat flow boiling model accurately predicted the local heat transfer coefficients measured in all these flow regimes with only two small modifications to their flow map (to extend its application to G < 100 kg/m2 s). Their flow boiling model was also successfully compared to the earlier ammonia flow boiling data of Chaddock and Buzzard (1986). The Gungor-Winterton (1987) correlation instead gave very poor accuracy for ammonia.

A Study of Condensation Heat Transfer in a Single Mini-Tube and a Review of Korean Micro- and Mini-Channel Studies

2003 ◽  
Author(s):  
M. H. Kim ◽  
J. S. Shin ◽  
C. Huh ◽  
T. J. Kim ◽  
K. W. Seo
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Flow Characteristics ◽  
Saturation Temperature ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Condensation Heat Transfer ◽  
Transfer Coefficients ◽  
Round Tube ◽  
Two Phase

This paper reviews recent Korean studies of flow characteristics, flow boiling, and flow condensation in micro- and mini-channels. The characteristics of local heat transfer and pressure drops were experimentally investigated using condensing R134a two-phase flow, in a single round tube, with an inner diameter of 0.691 mm. New experimental techniques were developed to measure the condensation heat transfer coefficient. Tests were performed for a mass flux of 100 to 600 kg/m2s, a heat flux of 5 to 20 kW/m2, and a saturation temperature of 40°C. The experimental local condensation heat transfer coefficients and two-phase frictional pressure gradients are shown. Comparisons of experimental data with existing models reveal that the correlations failed to predict the present data. This study contains the unique sub-millimeter-diameter, single round tube, condensation data reported in the literature.

Flow Morphology and Heat Transfer During Subcooled Flow Nucleate Boiling of HFE-7000 in Microchannels

2008 ◽  
Author(s):  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Transfer Coefficients ◽  
Subcooled Flow Boiling ◽  
Heat Transfer Coefficients ◽  
Subcooled Flow ◽  
Hydraulic Conditions ◽  
Parallel Microchannels ◽  
Bubble Agitation

Flow boiling was experimentally studied in parallel microchannels using coolant HFE-7000. Subcooled nucleate boiling was achieved under various thermal-hydraulic conditions for mass velocities ranging from G = 164 kg/m2·s to G = 3025 kg/m2·s. Local surface temperatures were measured and flow visualizations were conducted to obtain flow morphologies, boiling curves, and heat transfer coefficients during boiling process. It was found that heat transfer was significantly enhanced during subcooled flow boiling by bubble agitation of the liquid.

Visualization Study of Bubble Sliding Characteristics in a Subcooled Flow Boiling Narrow Rectangular Channel Under Natural Circulation Condition

2017 ◽  
Author(s):  
Kuan Yang ◽  
Xiaxin Cao ◽  
Changqi Yan ◽  
Yongyong Yang ◽  
Chunping Tian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Bubble Diameter ◽  
Number Density ◽  
Sliding Velocity ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Sliding Bubbles

Heat transfer enhancement by the motion of the bubbles sliding along the heating surface are wildly reported by many researchers, thus it is of great importance to quantitatively investigate the characteristics of sliding bubbles. A visualization study of subcooled flow boiling of water in a vertical single face-heated narrow rectangular channel under a series of natural circulation working conditions was conducted. Pictures of the bubble sliding behaviors were captured by a high speed camera simultaneously with thermal data. A sequence of digital image processing algorithms were applied to the original picture to extract bubble shape and location information, which post-processing methods were adopted to obtain characteristic sliding parameters (including the distribution of the equivalent sliding bubble diameter and velocity, number density of the sliding bubbles). It is found that bubbles can be able to nucleate and grow while sliding on the heating plate after the ONB point; the bubble number density, average bubble sliding velocity and the average sliding diameter continue to increase along the test section; heat transfer in the flow channel are significantly enhanced along flow direction with relatively low local void fraction. The average bubble sliding velocity near the inlet is significantly smaller than the sectional average velocity of single-phase fluid of the flow channel, and then it exceeded near the outlet of the test section. The average bubble sliding velocity and diameter increase with increasing heat flux and decreeing local subcooling degree. The equivalent diameter of sliding bubbles and the bubble sliding velocity approximately follow normal distribution. The distribution of the bubble diameter and velocity both cover a wild range. The standard deviations of the probability density function of the sliding bubble diameter and velocity increase with increasing heat flux and decreasing subcooling degree.

Local Heat Transfer for Subcooled Flow Boiling with Water

1992 ◽  
Vol 22 (4) ◽  
pp. 501-510 ◽  
Author(s):  
Ronald D. Boyd ◽  
Xiaowei Meng
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow
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