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Condensation of R134a on horizontal integral-fin titanium tubes.

Author(s) : FERNÁNDEZ-SEARA J., UHÍA F. J., DIZ R., et al.

Type of article: Article

Summary

Experimental research was conducted to evaluate the condensation of R134a on horizontal smooth and integral-fin (32 fpi) titanium tubes of 19.05 mm outer diameter. Experiments were carried out at saturation temperatures of 30, 40 and 50°C and wall subcoolings from 0.5 to 9°C. The results show that the condensation heat transfer coefficients (HTCs) on the smooth tubes are well predicted by the Nusselt theory with an average error of +2.38% and within a deviation between +0.13 and +5.42%. The enhancement factors provided by the integral-fin tubes on the overall condensation HTCs range between 3.09-3.94, 3.27-4 and 3.54-4.1 for the condensation temperatures of 30, 40 and 50°C, respectively. The enhancement factors increase by increasing the wall subcooling and with the rise of the condensing temperature. The condensate flooded fraction of the integral-fin tubes perimeter varies from 25 to 20% at saturation temperatures of 30 and 50°C, respectively. The correlation reported by Kang et al. (2007) predicted the experimental data with a mean deviation of -5.5%. [Reprinted with permission from Elsevier. Copyright, 2009].

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