Evaporation Heat Transfer and Pressure Drop of R-404A at Low Flow Rates in 9.5 mm O.D. Smooth and Microfin Tubes

A significant amount of studies were performed on evaporation heat transfer and pressure drop in microfin tubes. Most studies, however, focused on the refrigerants used in air-conditioners or heat pumps, and very limited information is available on R-404A, which is used in low temperature refrigeration. In this study, the evaporation heat transfer and pressure drop characteristics of R-404A in a 9.5 mm O.D. microfin tube were investigated for the mass flux range from 80 kg/ms and 200 kg/ms. A smooth tube of the same outer dimeter was also tested for comparison. The results showed that the heat transfer enhancement ratio of the microfin tube increased with increasing mass flux and the heat flux decreased. The relative contribution of the convective heat transfer and the heat flux on total heat transfer was attributed to the observed trend. The pressure drops of the microfin tube were slightly (maximum 28%) larger than those of the smooth tube. Existing correlations do not adequately predict the measured heat transfer coefficients of pressure drops, probably due to the test range of the present study, which is outside of the existing correlations.

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  S. Zivi.  Estimation of Steady-State Steam Void-Fraction by Means of the Principle of Minimum Entropy Production , 1964 .

[3]  S. L. Smith.  Void Fractions in Two-Phase Flow: A Correlation Based upon an Equal Velocity Head Model , 1969 .

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

[5]  A. M. Judd.  Convective Boiling and Condensation. , 1973 .

[6]  M. Shah.  Chart correlation for saturated boiling heat transfer: Equations and further study , 1982 .

[7]  H. Müller-Steinhagen,et al.  A simple friction pressure drop correlation for two-phase flow in pipes , 1986 .

[8]  K. Gungor,et al.  Simplified general correlation for saturated flow boiling and comparisons of correlations with data , 1987 .

[9]  R. Radermacher,et al.  Prediction of Pressure Drop during Horizontal Annular Flow Boiling of Pure and Mixed Refrigerants , 1989 .

[10]  Chi-Chuan Wang,et al.  Horizontal flow boiling of R22 and R407C in a 9.52 MM micro-fin tube , 1996 .

[11]  J. Thome.  Boiling of new refrigerants: a state-of-the-art review , 1996 .

[12]  John R. Thome,et al.  Evaporation in Microfin Tubes: A Generalized Prediction Model , 1997 .

[13]  A. Cavallini,et al.  Pressure drop during condensation and vaporisation of refrigerants inside enhanced tubes , 1997 .

[14]  M. Kim,et al.  Enhanced Effect of a Horizontal Micro-fin Tube for Condensation Heat Transfer with R22 and R410A , 2000 .

[15]  S. Sami,et al.  Prediction of convective boiling characteristics of alternatives to R-502 inside air/refrigerant enhanced surface tubing , 2000 .

[16]  丁伟,et al.  Heat-transfer pipe , 2000 .

[17]  M. Goto,et al.  Condensation and evaporation heat transfer of R410A inside internally grooved horizontal tubes , 2001 .

[18]  R. Shah,et al.  An Assessment of Refrigerant Heat Transfer, Pressure Drop, and Void Fraction Effects In Microfin Tubes , 2001 .

[19]  M. Kedzierski,et al.  Generalized Pressure Drop Correlation for Evaporation and Condensation in Smooth and Micro-Fin Tubes | NIST , 2001 .

[20]  R. Yun,et al.  A generalized correlation for evaporation heat transfer of refrigerants in micro-fin tubes , 2002 .

[21]  J. Chung,et al.  Evaporation heat transfer characteristics of R-410A in 7 and 9.52 mm smooth/micro-fin tubes , 2002 .

[22]  A. ADoefaa,et al.  ? ? ? ? f ? ? ? ? ? , 2003 .

[23]  E. Filho,et al.  Convective boiling pressure drop of refrigerant R-134a in horizontal smooth and microfin tubes , 2004 .

[24]  J. Thome,et al.  Investigation of Flow Boiling in Horizontal Tubes: Part II, Development of a New Heat Transfer Model for Stratified-Wavy, Dryout and Mist Flow Regimes , 2005 .

[25]  J. Thome,et al.  Flow pattern based two-phase frictional pressure drop model for horizontal tubes, Part II: New phenomenological model , 2007 .

[26]  P. Mago,et al.  Modelling of evaporation heat transfer of pure refrigerants and refrigerant mixtures in microfin tubes , 2007 .

[27]  M. Kedzierski,et al.  Horizontal Convective Boiling of Pure and Mixed Refrigerants within a Micro-Fin Tube , 2008 .

[28]  Haitao Hu,et al.  Heat transfer characteristics of R410A–oil mixture flow boiling inside a 7 mm straight microfin tube , 2008 .

[29]  D. D. Col,et al.  Experimental study on flow boiling of R134a and R410A in a horizontal microfin tube at high saturation temperatures , 2011 .

[30]  A. S. Dalkılıç,et al.  A REVIEW ON THE HEAT-TRANSFER PERFORMANCE AND PRESSURE-DROP CHARACTERISTICS OF VARIOUS ENHANCED TUBES , 2012 .

[31]  Nae-Hyun Kim,et al.  CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF R-410A IN THREE 7.0MM OUTER DIAMETER MICROFIN TUBES HAVING DIFFERENT INSIDE GEOMETRIES , 2013 .

[32]  A. Cavallini,et al.  Condensation flow patterns inside plain and microfin tubes: a review. , 2013 .

[33]  Felix Hueber,et al.  Principles Of Enhanced Heat Transfer , 2016 .

[34]  J. Yu,et al.  Forced Convective Flow Boiling Heat Transfer of Pure Refrigerants Inside a Horizontal Microfin Tube , 2019, Convective Flow Boiling.

[35]  Tsuyoshi Murata,et al.  {m , 1934, ACML.