(1) For the airside performance for N = 1 with a smaller fin pitch of 1.6 mm, the heat transfer coefficient for the louver fin
geometry is higher than that of semi-dimple VG and plain fin geometry. For a larger fin pitch of 2.0 mm, the semi-dim-
ple VG is marginally higher than that of louver fin geometry when the frontal velocity is lower than 2 m s1 due to the
increasing effect of swirled motion. However, the trend is reversed where the louver fin outperforms that of semi-dim-
ple VG when the velocity is increased further. The heat transfer coefficient for louver fin outperforms that of semi-dimple VG due to appreciable contribution of mixing.
(2) For the airside performance of N =2or N = 4, the heat transfer coefficients for louver fin geometry is about 2–15% higher than those of the semi-dimple VG geometry. The difference is increased with the rising velocity and the results prevail for both fin pitches. However, the difference is smaller at a larger fin pitch due to comparatively effectively swirled
motion.
(3) The effect of the number of tube row on the heat transfer coefficients is negligible for louver fin geometry and is also
small for the semi-dimple VG configuration. For the plain fin geometry, the effect of tube row is also small when
N > 1. The heat transfer performance for N = 1 is different from N =2or N = 4 due to its inline configuration.