Free Convection from a One End Closed Vertical Pipe with Annular Fins: A Computational Study

Cylindrical objects in heat transfer applications have always taken the spotlight due to their compact nature and better surface area-to-volume ratio over their cuboid counterparts. Despite this advantage, fins have been used to enhance the heat transfer properties of such geometries. This study involves one such geometry where the top of the cylinder is open to the surrounding atmosphere and the cylinder is fitted with annular fins of different sizes and spacing. The k-ε model is used to simulate the turbulent cases along with a density-based solver. The cylinder is modeled to be a heat source with a constant temperature of 350 K and the surrounding atmosphere being air at 300 K. Nusselt number and effectiveness of the fins were calculated and analyzed. The heat flow rate experienced a maximum increase of 50% when the number of fins is raised from S/d 0.9 to S/d 0.3. The maximum effectiveness occurs at Ra = 1011, with a value of 4.44 observed for S/d of 0.3 and d/D of 0.25. The maximum values for effectiveness are observed at lower d/D and S/d values.