Condensation Heat Transfer of Carbon Dioxide Inside Horizontal Smooth and Microfin Tubes at Low Temperatures

This paper presents heat transfer data for the condensation of CO 2 at low temperatures in horizontal smooth and microfin tubes. The test tubes included a 3.48 mm inner diameter smooth tube and a 3.51 mm melt-down diameter microfin tube. The test was performed over a mass flux range of 200-800 kg/m 2 s and at saturation temperatures of -25°C and -15°C, respectively. The effect of various parameters-diameter, mass flux, vapor quality, and temperature difference between inner wall and refrigerant-on heat transfer coefficient and enhancement factor is analyzed. The data are compared with several correlations. The existing correlations for the smooth tube mostly overpredicted the heat transfer coefficients of the present study, which is possibly resulted from the characteristics of carbon dioxide as a "high pressure refrigerant." For the microfin tubes, due to the complexity and variety of fin geometry and flow mechanisms in microfin tubes, most of the correlations for the microfin tube were not applicable for the experimental data of the present study. The average enhancement factors and penalty factors evidenced that it was not always true that the internally finned geometry guaranteed the superior in-tube condensation performance of the microfin tube in refrigeration and air-conditioning systems.

[1]  S. Rouhani,et al.  CALCULATION OF VOID VOLUME FRACTION IN THE SUBCOOLED AND QUALITY BOILING REGIONS , 1970 .

[2]  Robert J. Moffat,et al.  Describing the Uncertainties in Experimental Results , 1988 .

[3]  O. García-Valladares,et al.  Review of In-Tube Condensation Heat Transfer Correlations for Smooth and Microfin Tubes , 2003 .

[4]  M. Kedzierski,et al.  Horizontal Convective Condensation of Alternative Refrigerants Within a Micro-Fin Tube , 1997 .

[5]  J. Thome,et al.  Condensation in Horizontal Tubes, Part 1: Two-Phase Flow Pattern Map , 2003 .

[6]  H. M. Soliman,et al.  On the annular‐to‐wavy flow pattern transition during condensation inside horizontal tubes , 1982 .

[7]  A. Cavallini,et al.  A DIMENSIONLESS CORRELATION FOR HEAT TRANSFER IN FORCED CONVECTION CONDENSATION , 1974 .

[8]  N. Z. Azer,et al.  A general heat transfer correlation for condensation inside internally finned tubes , 1988 .

[9]  M. Shah.  A general correlation for heat transfer during film condensation inside pipes , 1979 .

[10]  Michael B. Pate,et al.  Heat transfer and pressure drop during evaporation and condensation of R22 in horizontal micro-fin tubes☆ , 1989 .

[11]  H. Honda,et al.  Condensation of refrigerants in horizontal, spirally grooved microfin tubes : Numerical analysis of heat transfer in the annular flow regime , 2000 .

[12]  Michael B. Pate,et al.  Evaporation and condensation heat transfer and pressure drop in horizontal, 12.7-mm microfin tubes with refrigerant 22 , 1990 .

[13]  J. Thome,et al.  Flow Boiling in Horizontal Tubes. Part 1; Development of a Diabatic Two–Phase Flow Pattern Map , 1998 .

[14]  A. Cavallini,et al.  Heat transfer and pressure drop during condensation of refrigerants inside horizontal enhanced tubes , 2000 .

[15]  R. Webb,et al.  A Predictive Model for Condensation in Small Hydraulic Diameter Tubes Having Axial Micro-Fins , 1997 .

[16]  P. Hrnjak,et al.  Adiabatic Horizontal and Vertical Pressure Drop of Carbon Dioxide Inside Smooth and Microfin Tubes at Low Temperatures , 2008 .

[17]  Davide Del Col,et al.  Condensation inside and outside smooth and enhanced tubes: a review of recent research , 2003 .

[18]  C. L. Tien,et al.  GENERAL FILM CONDENSATION CORRELATIONS , 1987 .

[19]  S. Koyama,et al.  Condensation Heat Transfer of Pure Refrigerants in Microfin Tubes , 1998 .

[20]  H. Jaster,et al.  Condensation heat transfer in a mixed flow regime , 1976 .

[21]  Masao Goto,et al.  Condensation heat transfer of R410A inside internally grooved horizontal tubes , 2003 .

[22]  A. Yokozeki,et al.  Heat Transfer Coefficients and Transport Properties for Alternative Refrigerants , 1994 .

[23]  L. Chamra,et al.  Advanced micro-fin tubes for condensation , 1996 .

[24]  John C. Chato,et al.  Laminar condensation inside horizontal and inclined tubes , 1960 .

[25]  J. Thome,et al.  Condensation in horizontal tubes, part 2: new heat transfer model based on flow regimes , 2003 .

[26]  J. Chato,et al.  Condensation in Smooth Horizontal Tubes , 1998 .

[27]  Predrag Stojan Hrnjak,et al.  Condensation of CO2 at Low Temperatures , 2004 .