Extended surfaces

Abstract

Convection from a solid surface to a surrounding fluid is limited by the area of that surface. It would seem reasonable, therefore, that if the surface area could be extended, then a gain in total heat transfer would be achieved. This is done by adding fins to the surface. Heat transfer is then by conduction along the fin, and by convection from the surface of the fin. It is likely that the convection coefficient of the basic surface will be altered by the addition of fins, due to the new flow pattern involved and the fact that the temperature of the fin surface will not be uniform. Though the average surface temperature is reduced by the addition of fins, the total heat transfer is increased. In the treatment that follows it is assumed that the convection coefficient is known. The Nusselt numbers of finned surfaces may be determined experimentally.