The effect of coating and interface resistance on thermal performance of variable thickness annular composite fins

The non-dimensional finite element method is used to study performance characteristics of annular fins when subjected to both interface resistance as well as coating layer over the fin surface. Governing dimensionless parameters are identified for coating and interface resistance effects. It is found that the coating (interface) effects are governed by a single dimensionless parameter that groups all important material and geometric parameters of the fin substrate and coating (interface) layer. The analysis is first conducted for a rectangular profile or constant thickness fin, over the range of fin lateral Biot number 0.001 ⩽ Bizf ⩽ 1, which showed an upper bound of the governing dimensionless parameters for which the coating and interface effects become negligible. The investigation is then extended to variable thickness profile annular fins, which showed the behavior of coating and interface resistances very similar to that of rectangular profile.

► The efficiency of composite annular fins with interface resistance is studied. ► It is found that the coating thermal conductivity and thickness effects are governed by a single dimensionless parameter. ► It is found that the interface thermal conductivity and thickness effects are governed by a single dimensionless parameter. ► The effect of interface resistance is more than the coating for the same values of corresponding dimensionless parameters. ► The coating and interface effects are similar for all considered fin profiles.