An experimental investigation was performed for convective condensation of R410A inside one smooth tube (3.78 mm, inner diameter) and six microfin tubes (4.54, 4.6 and 8.98 mm, fin root diameter) of different geometries for mass fluxes ranging from 99 to 603 kg m−2s−1. The experimental data were analyzed with updated flow pattern maps and evaluated with existing correlations. The heat transfer coefficient in the microfin tubes decreases at first and then increases or flattens out gradually as mass flux decreases. This obvious nonmonotonic heat transfer coefficient-mass flux relation may be explained by the complex interactions between the microfins and the fluid, mainly by surface tension effects. The heat transfer enhancement mechanism in microfin tubes is mainly due to the surface area increase at large mass fluxes, while liquid drainage by surface tension and interfacial turbulence enhance heat transfer greatly at low mass fluxes.
Convective Condensation Inside Horizontal Smooth and Microfin Tubes
Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received October 26, 2012; final manuscript received December 19, 2013; published online March 6, 2014. Assoc. Editor: W. Q. Tao.
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Wu, Z., Sundén, B., Wang, L., and Li, W. (March 6, 2014). "Convective Condensation Inside Horizontal Smooth and Microfin Tubes." ASME. J. Heat Transfer. May 2014; 136(5): 051504. https://doi.org/10.1115/1.4026370
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