Condensation Heat Transfer of Soliman Flow Pattern in Mini-Channel

2006 ◽  
Author(s):  
Q. Chen ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Flow Pattern ◽  
Flow Regime ◽  
Flow Region ◽  
Condensation Heat Transfer ◽  
Heat Transfer Correlation ◽  
Transfer Coefficients ◽  
Annular Regime ◽  
Fin Tubes

The condensation heat transfer for R134a in the two kinds of in-tube three-dimensional (3-D) micro-fin tubes with different geometries is experimentally investigated. Based on the flow pattern observations, the flow patterns in the Soliman flow regime map are divided into two-flow regimes; one with the vapor-shear-dominant annular regime and the other with the gravitational-force-dominant stratified-wavy regime. In the annular regime, the heat transfer coefficients of the two kinds of in-tube 3-D micro-fin tubes decreases as the vapor quality decreases. The regressed condensation heat transfer correlation from the experimental data of the annular flow region is obtained. The dispersibility of the experimental data is inside the limits of ±25%. In the stratified-wavy regime, the average heat transfer coefficient of the two kinds of in-tube 3-D micro fin tubes increases as the mass flux increases and the number of micro fins in the 3-D micro-fin tube is not the controlling factor for performance of a condensation heat transfer. The regressed condensation heat transfer correlation of the stratified-wavy flow regime is experimentally obtained. The dispersibility of the experimental data is inside the limits of ±22%. Combined with the criteria of flow pattern transitions, the correlations can be used for the design of a condenser with 3-D micro fin tubes.

Correlation Investigation of Condensation Heat Exchanger Design for Secondary Passive Cooling System

2012 ◽  
Author(s):  
Hee Joon Lee ◽  
Han-Ok Kang ◽  
Tae-Ho Lee ◽  
Cheon-Tae Park
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Cooling System ◽  
Condensation Heat Transfer ◽  
Passive Cooling ◽  
Heat Transfer Correlation ◽  
Data Set ◽  
Heat Exchanger Design ◽  
Passive Cooling System

Recently vertical or horizontal type condensation heat exchangers are being studied for the application to secondary passive cooling system of nuclear plants. To design vertical condensation heat exchanger in water pool, a thermal sizing program of condensation heat exchanger, TSCON (Thermal Sizing of CONdenser) was developed in KAERI (Korea Atomic Energy Research Institute). In this study, condensation heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without non-condensable gas (pure steam condensation). From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah correlation showed most satisfactory results for the heat transfer coefficient and mass flow rate in a heat exchanger in both subcooled and saturated water pools without the presence of non-condensable gas.

A New Heat Transfer Correlation and Flow Regime Map for Tube Bundles

1990 ◽  
Vol 112 (1) ◽  
pp. 150-156 ◽  
Author(s):  
Y. A. Hassan ◽  
T. K. Blanchat
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Steam Generator ◽  
Tube Bundle ◽  
Nucleate Boiling ◽  
Heat Transfer Correlation ◽  
Transfer Coefficients ◽  
Tube Bundles ◽  
Regime Map ◽  
Flow Regime Map

A RELAP5/MOD2 computer code model for a once-through steam generator has been developed. The calculated heat transfer in the nucleate boiling flow was underpredicted as shown by a predicted superheat of only 11°C (20°F), whereas plant values range from 22–30°C (40–60°F). Existing heat transfer correlations used in thermal-hydraulic computer codes do not provide accurate predictions of the measurement-derived secondary convective heat transfer coefficients for steam generators because they were developed for flow inside tubes, not tube bundles. The RELAP5/MOD2 flow regime map was modified to account for flow across bundles. This modified flow regime map predicts better transition criteria between bubbly-to-slug and slug-to-annular flow. Consequently, improved saturated conditions for the fluid flow at the entrance to the boiler were obtained. A modified Chen-type heat transfer correlation was developed to predict the boiling heat transfer for steam generator tube bundle geometries. This correlation predicts better superheat.

A Review about Condensation Heat Tansfer with Non-Condensable Gases

2012 ◽  
Vol 516-517 ◽  
pp. 239-242 ◽  
Author(s):  
Jun Xia Zhang ◽  
Bin Yao Gong
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Wall Temperature ◽  
Condensation Heat Transfer ◽  
Transfer Coefficients ◽  
Enhancement Of Heat Transfer ◽  
Improve Efficiency ◽  
Heat Transfer Coefficients ◽  
Geometric Conditions ◽  
Performance Of Heat Transfer

Non-condenable gases decrease performance of heat transfer by degrading condensation of vapor. Therefore, to comprehend the mechanism that non-condensable gases affect condensation heat transfer is helpful to improve efficiency of heat transfer of devices.At the present work, the update development of experimental and theoretical researches about condensation heat transfer with non-condensable gases were present. These findings report effects of non-condensable gases on parameters, including condensation heat transfer coefficients, flow pattern and wall temperature. Meanwhile, variations of condensation heat transfer in the presence of non-condensable gases with various conditions, involving geometric conditions, flow pattern and species of non-condensable gases. By the contrast, the enhancement of heat transfer of condensation with non-condensable gases should give more concerns.

An Experimental Investigation of Flow Patterns During Condensation of HFC Refrigerants in Horizontal Micro-Fin Tubes

2019 ◽  
Vol 27 (01) ◽  
pp. 1950010
Author(s):  
Sanjeev Singh ◽  
Rajeev Kukreja
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Flow Regimes ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes ◽  
Regime Map ◽  
Fin Tubes ◽  
Flow Regime Map

Condensation heat transfer coefficients and flow regimes in two different horizontal micro-fin tubes are examined during the condensation of refrigerants R-134a and R-410A. The present investigation has focused on determination and prediction of condensation heat transfer coefficients and finding the interrelation between heat transfer coefficients and the prevailing flow regimes. During flow visualization, flow regimes have been captured using borosilicate glass tube at inlet and outlet of the test condenser using high speed digital camera. Stratified, stratified wavy, wavy annular, annular, slug and plug flows have been observed at different mass fluxes and vapor qualities of the refrigerants. The observed flow regimes are compared with the existing flow regime maps proposed by Breber et al. [Prediction of horizontal tube side condensation of pure components using flow regime criteria, J. Heat Transfer 102 (1980) 471–476], Tandon et al. [A new flow regime map for condensation inside horizontal tubes, J. Heat Transfer 104 (1982) 763–768.] and Thome et al. [Condensation in horizontal tubes, part 2: New heat transfer model based on flow regimes, Int. J. Heat Mass Transfer 46 (2003) 3365–3387.] Thome et al. [Condensation in horizontal tubes, part 2: New heat transfer model based on flow regimes, Int. J. Heat Mass Transfer 46 (2003) 3365–3387.] flow regime map shows good agreement with experimental data.

Nucleate Boiling in Thermally Developing and Fully Developed Laminar Falling Water Films

1988 ◽  
Vol 110 (1) ◽  
pp. 221-228 ◽  
Author(s):  
M. Cerza ◽  
V. Sernas
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Nucleate Boiling ◽  
Heat Transfer Correlation ◽  
Transfer Coefficients ◽  
Number Range ◽  
Flow Rates ◽  
Entry Length ◽  
Heat Transfer Coefficients ◽  
Water Films

This paper reports an experimental investigation of nucleate boiling in thin water films falling down the outside of a cylindrical heated tube. A mathematical model for the convective (nonboiling) heat transfer coefficient in the laminar thermal entry length was developed and used as a comparison to the experimental boiling heat transfer coefficients. A heat transfer correlation based on mechanistic arguments is presented and is shown to represent the experimental data fairly well. The experimental data were also compared with existing heat transfer data in the literature. The flow rates utilized in this study corresponded to a Reynolds number range from 670 and 4300 and the heat flux range was 6 to 70 kW/m2.

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