Assessment of Thermal Performance of Semicircular Fin under Forced Air Convection: Application to Air-preheater

The performance of semi-circular fins subjected to forced convection has been studied analytically. The expression for its efficiency has been derived by solving a two-dimensional thermal energy balance equation and the computed efficiency has been compared with an equal volume circular fin. Under the operating conditions studied, the thermal efficiency of the semi-circular fin exceeded that of its circular counterpart. The effects of various parameters on the heat transfer coefficient and the exit air temperature have been determined for semi-circular finned air preheater. The heat transfer coefficient under forced air convection has been found to increase with an increment of the air velocity and reduction in the tube pitch, pipe size and fin spacing. The extent of air-preheats increases with an increase in pipe size and decrease in fin spacing, air velocity and tube pitch. Due to higher thermal performance of semi-circular fins compared to circular fins under identical conditions, improved energy efficiency can be achieved in air pre-heater.