In this study

the surface heat transfer coefficient was selected as the evaluation index and the two-phase flow condensation heat transfer characteristics of R134a inside a horizontal micro-fin tube with 6.35 mm outer diameter were studied. The effects of the test conditions and structural parameters of the micro-fin tube on the surface heat transfer coefficient were analyzed. Correlations of Cavallini et al.

Miyara et al.

and Oliver et al. were also applied to predict the surface heat transfer coefficient inside the micro-fin tube. We found that the correlation of Cavallini et al. was the most effective at predicting the heat transfer characteristics

where the average and mean deviations of predicted and experimental values were ﹣21.47% and 21.94%

respectively. Although the average and mean deviations of the predicted and experimental values of the correlation of Miyara et al. were 16.21% and 30.65%

respectively

the margin of deviation was ﹣47.12% to 82.32%

which indicates that a greater deviation still exists between the predicted and experimental values under certain conditions for the correlation of Miyara et al.. The predictive ability of the correlation of Oliver et al. was the worst of the three correlations

where the average deviation of the predicted and experimental values was ﹣54.93%. The correlation of Oliver et al. was thus modified based on the experimental data

and its predictive ability was improved greatly

where the average and mean deviations of the predicted and experimental values were ﹣2.37% and 10.77%

respectively.