International Journal of Air-Conditioning and Refrigeration

The Society of Air-Conditioning and Refrigerating Engineers of Korea (대한설비공학회)
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Reduction of the Wet Surface Heat Transfer Coefficients from Experimental Data

  • Published : 2004.03.01
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Abstract

Four different data reduction methods for the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two heat and mass transfer models and two fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the reduced heat transfer coefficients revealed that the single potential heat and mass transfer model yielded the humidity-independent heat transfer coefficients. Two fin efficiency models-enthalpy model and humidity model-yielded approximately the same fin efficiencies, and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

Keywords

References

  1. ARI 410-81, Standard for forced-circulation air-cooling and air-heating coils, American Refrigeration Institute
  2. McQuiston, F. C., 1975, Fin efficiency with combined heat and mass Transfer, ASHRAE Trans., Vol. 81, No.1, pp.350-355
  3. McQuiston, F. C., 1978, Heat, mass and momentum transfer data for five plate-fin-tube surfaces, ASHRAE Trans., Vol. 84, Part I, pp.266-293
  4. Wang, C.-C., Hsieh, Y.-C. and Lin, Y.-T., 1997, Performance of plate finned tube heat exchangers under dehumidifying conditions, J. Heat Transfer, Vol. 119, pp.109-117
  5. Eckels, P. W. and Rabas, T. J., 1987, Dehumidification: on the correlation of wet and dry transport process in plate finned-tube heat exchangers, J. Heat Transfer, Vol. 109, pp. 575-582
  6. Mirth, D. R., Ramadhyani, S. and Hittle, D. C., 1993, Thermal performance of chilled water cooling coils at low water velocities, ASHRAE Trans., Vol. 99, Pt. 1, pp.43-53
  7. Hong, K. and Webb, R. L., 1999, Perfor mance of dehumidifying heat exchangers with and without wetting coatings, J. Heat Transfer, Vol. 121, pp. 1018-1026
  8. ASHRAE Standard 41.1, 1986, Standard method for temperature measurement, ASHRAE
  9. ASHRAE Standard 41.2, 1986, Standard method for laboratory air-flow measurement, ASHRAE
  10. ASHRAE Standard 41.5, 1986, Standard measurement guide, engineering analysis of experimental data, ASHRAE
  11. Taborek, J, 1998, F and ${\theta}$ charts for crossflow arrangements, in Heat Transfer Enhancement of Heat Exchangers, Eds., S. Kakac, A. E. Bergles, F. Mayinger, H. Yuncu, Kluwer Academic Press, pp.141-162
  12. Gnielinski, V., 1976, New equations for heat and mass transfer in turbulent pipe flows, Int. Chem. Eng., Vol. 16, pp.359-368
  13. Schmidt, T. E., 1949, Heat transfer calculations for extended surfaces, J ASRE, Refrigeration Engineering, Vol. 4, pp.351-357
  14. Ware, H. and Hacha, T., 1960, Heat transfer from humid air to fin and tube extended surface cooling coils, ASME Paper No.60, HT-17
  15. Wu, G. and Bong, T. Y. 1994, Overall efficiency of a straight fin with combined heat and mass transfer, ASHRAE Trans., Pt. 1, Vol. 100, pp.367-374
  16. Lin, Y. T., Hsu, K. C., Chang, Y. J and Wang, C. C., 2001, Performanace of rectangular fin in wet conditions: visualization and wet fin efficiency, J Heat Transfer, Vol. 123, pp. 827-836
  17. Hong, K. and Webb, R. L., 1996, Calculation of fin efficiency for wet and dry fins, Int. J HVAC & R Research, Vol. 2, No.1, pp.27-4