Study on Condensation Heat Transfer Characteristics of Nonazeotropic Binary Refrigerant Mixture R1234yf/R32 Inside Small-Scale Horizontal Smooth Tubes

In this study, condensation heat transfer characteristics of nonazeotropic mixtures R1234yf and R32 (mass fractions of 0.52:0.48 and 0.77:0.23, respectively) inside a horizontal smooth tube (inner diameter 2 mm) were experimentally investigated at mass fluxes ranging from 100 to 400 kg/m2 s and at a saturation temperature of 40 °C. A prediction model using a modified heat transfer correlation for pure refrigerant was constructed, the details of which are presented here. The heat transfer characteristics, especially the heat transfer deterioration caused by the mass transfer difference of the nonazeotropic refrigerant mixture, were evaluated by combining the correlations of heat transfer and mass transfer on both the vapor side and the liquid side. Through comparison with experimental data, the obtained prediction results were found to agree reasonably with the experimental condensation heat transfer coefficient of binary refrigerant mixtures using R1234yf and R32.

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Experimental Study on Condensation Heat Transfer and Flow Modes of R245fa on Enhanced Surface Tubes

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132515500145 ◽

2015 ◽

Vol 23 (02) ◽

pp. 1550014 ◽

Cited By ~ 8

Author(s):

Daisuke Jige ◽

Tomonobu Matsuno ◽

Norihiro Inoue

Keyword(s):

Heat Transfer ◽

Saturation Temperature ◽

Condensation Heat Transfer ◽

Flow Mode ◽

Heat Transfer Characteristics ◽

Enhanced Heat Transfer ◽

Finned Tubes ◽

Transfer Characteristics ◽

Grooved Tube ◽

Enhanced Surface

The present study experimentally investigated the condensation heat transfer characteristics and condensate flow mode of R245fa on horizontal low-finned and microscopic-grooved tubes. Five low-finned tubes and a microscopic-grooved tube with tube diameters at the fin tip of approximately 19 mm were used. Experiments were conducted at a saturation temperature of 40°C. The fundamental heat transfer characteristics of the low-finned and microscopic-grooved tubes were experimentally investigated to clarify the flow modes of the condensate and the efficacy of the enhanced heat transfer.

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A Semi-Empirical Model for Condensation Heat Transfer Coefficient of Mixed Ethanol-Water Vapors

Journal of Heat Transfer ◽

10.1115/1.4003433 ◽

2011 ◽

Vol 133 (6) ◽

Cited By ~ 9

Author(s):

Yang Li ◽

JunJie Yan ◽

JinShi Wang ◽

GuoXiang Wang

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Empirical Model ◽

Condensation Heat Transfer ◽

Dropwise Condensation ◽

Heat Transfer Characteristics ◽

Transfer Coefficients ◽

Heat Transfer Coefficients ◽

Transfer Characteristics ◽

Semi Empirical

A semi-empirical model describing the heat transfer characteristics of the pseudo-dropwise condensation of binary vapor on a cooled vertical tube has been formulated. By ignoring the thin film always present on the condensation surface and the intensification of mass transfer caused by the Marangoni effect, the heat transfer characteristics of pseudo-dropwise condensation are tentatively formulated. The model involved an analysis of the diffusion process in the vapor boundary layer along with the heat transfer process through the condensate drops. This model was applied to the condensation of the saturated binary vapor of ethanol and water, and was examined using experimental data at vapor pressure values of 101.33 kPa (provided by Utaka and Wang, 2004, “Characteristic Curves and the Promotion Effect of Ethanol Addition on Steam Condensation Heat Transfer,” Int. J. Heat Mass Transfer, 47, pp. 4507–4516), 84.52 kPa and 47.36 kPa. Calculations using the model show a similar trend to the experimental measurements. With the change of the vapor-to-surface temperature difference, the heat transfer coefficients revealed nonlinear characteristics, with the peak values under all ethanol mass fractions of binary vapor. The heat transfer coefficients increased with decreasing ethanol mass fraction.

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