Heat transfer and fluid flow of air across corrugated tube bundles

The characteristics of pressure drop and heat transfer of air across the corrugated tubes with three values of row number were investigated experimentally by measuring the average heat transfer coefficients and friction factors. The results were compared with that of the corresponding same row number smooth tube bundles. The corresponding correlation for the Nusselt numbers and Euler numbers vs. the Reynolds numbers for the corrugated tubes were obtained. It was found that the corrugated tube bundles will reach the developed state at a smaller row number compared with the smooth tube bundles. Within the range of Reynolds numbers of the present work, the heat transfer coefficients and the friction factors of the corrugated tube bundles were 13.6%-29.2% and 3.2%-60.0% higher than those of the smooth tube bundles respectively.