Effect of elliptical winglet on the air-side performance of fin-and-tube heat exchanger

This study numerically examines the elliptical winglets (EW) on the overall performance of fin-and-tube heat exchanger. The major geometrical parameters characterizing the EW has been investigated thoroughly, including the winglet location, attack angle and the trailing angle of the elliptical winglets with two different winglet lengths which are 1.0 mm and 1.5 mm. The numerical results indicate that the elliptical winglets with the 30° attack angle, 0 mm horizontal distance, 6 mm vertical distance and 120° trailing angle of both winglet lengths shows the highest performance. The heat transfer coefficients and pressure drops obtained by both winglet sizes are larger than that of the plain fin by about 13% and 35%, respectively. In term of the performance efficiency index, the 1.5 mm winglet length indicates about 1.8-2.9% improvement relative to plain fin geometry and the efficiency index of 1.0 mm winglet length is comparable with that of the plain fin.