We investigate the effective heat transfer in complex systems involving porous media and surrounding fluid layers in the context of mathematical homogenization. We differentiate between two fundamentally different cases: Case (a), where the solid part of the porous media consists of disconnected inclusions, and Case (b), where the solid matrix is connected. For both scenarios, we consider a heat equation with convection where a small scale parameter \varepsilon > 0 characterizes the heterogeneity of the porous medium and conducts a limit process \varepsilon \rightarrow 0 via two-scale convergence for the solutions of the \varepsilon -problems. In Case (a), we arrive at a one-temperature problem exhibiting a memory term and in Case (b) at a two-phase mixture model. We compare and discuss these two limit models with several simulation studies both with and without convection.