EVALUATION OF CONDENSATION HEAT TRANSFER CORRELATIONS FOR THE ANNULAR FLOW REGIME IN MICROFIN TUBES

2018 ◽  
Author(s):  
Zhi-chuan Sun ◽  
Wei Li ◽  
Wei Chen ◽  
Yan He
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Annular Flow ◽  
Condensation Heat Transfer ◽  
Heat Transfer Correlations ◽  
Microfin Tubes

On the Application of Macro-Pipe Two-Phase Heat Transfer Correlations and Flow Regime Maps to Mini-Channels

2006 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Ilai Sher ◽  
Emil Rahim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Regime ◽  
Annular Flow ◽  
Negative Slope ◽  
Two Phase ◽  
Heat Transfer Correlations ◽  
Two Phase Heat Transfer ◽  
Flow Regime Maps

The present study is aimed at evaluating the ability of conventional “macro-pipe” correlations and regime transitions to predict the two-phase thermofluid characteristics of mini-channel cold plates. Use is made of the Taitel-Dukler flow regime maps, seven classical heat transfer coefficient correlations and two dryout predictions. The vast majority of the mini-channel two-phase heat-transfer data, taken from the literature, is predicted to fall in the annular regime, in agreement with the reported observations. A characteristic heat transfer coefficient locus has been identified, with a positive slope following the transition from Intermittent to Annular flow and a negative slope following the onset of partial dryout at higher qualities. While the classical two-phase heat transfer correlations are generally capable of providing good agreement with the low-quality annular flow data the quality at which partial dryout occurs and the ensuing heat transfer rates are not predictable by the available macro-pipe correlations.

Condensation of Refrigerants in Horizontal, Spirally Grooved Microfin Tubes: Numerical Analysis of Heat Transfer in the Annular Flow Regime

1999 ◽  
Vol 122 (1) ◽  
pp. 80-91 ◽  
Author(s):  
S. Nozu ◽  
H. Honda
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Thick Film ◽  
Annular Flow ◽  
Local Heat Transfer ◽  
Film Condensation ◽  
Observation Study ◽  
Absolute Deviation ◽  
Laminar Film Condensation ◽  
Microfin Tubes

A method is presented for estimating the condensation heat transfer coefficient in a horizontal, spirally grooved microfin tube. Based on the flow observation study performed by the authors, a laminar film condensation model in the annular flow regime is proposed. The model assumes that all the condensate flow occurs through the grooves. The condensate film is segmented into thin and thick film regions. In the thin film region formed on the fin surface, the condensate is assumed to be drained by the combined surface tension and vapor shear forces. In the thick film region formed in the groove, on the other hand, the condensate is assumed to be driven by the vapor shear force. The present and previous local heat transfer data including four fluids (CFC11, HCFC22, HCFC123, and HFC134a) and three microfin tubes are found to agree with the present predictions to a mean absolute deviation of 15.1 percent. [S0022-1481(00)01501-2]

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