Experimental investigation of forced convection heat transfer over horizontal tube with conical fins for different fin spacings and different inclination angles

This research was performed to experimentally study the heat transfer over a horizontal tube with conical fins for different fin spacings and different inclination angles. The air entering the test section first contacts the large surface of the conical fin. Therefore the conical fin both directs the air towards the heating surface and increases the heat transfer surface area. The experiments were conducted for three different inclination angles (45 degrees, 60 degrees and 80 degrees) and three different fin spacings (10,12, and 15 mm). Water and air were used as hot and cold fluid in these experiments, respectively. The water temperature, which was the heating fluid, was kept fixed at 65 degrees C. The cold fluid entered the test section at eight different air flow velocities (2-20 m/s). Experimental results indicated that the Nusselt number at each inclination angle for the 10 mm fin spacing was almost the same. Moreover, for the 15 mm fin spacing, the highest Nusselt number was obtained at 80 degrees and lowest at 60 degrees for Re > 5 x 10(4), while the Nusselt number was almost the same at each inclination angle for Re < 5 x 10(4). It was determined that the lowest pressure drop was obtained at 80 degrees for both 10 and 15 mm.