Heat transfer in packed beds is of major importance for numerous engineering applications and determines signi„cantly the ef„ciency of both energy generation and transforming processes. Complementary to experimental investigations, the newly introduced extended discrete element method (XDEM) offers an innovative and versatile numerical concept to reveal the underlying physics of heat transfer in „xed and moving beds of granular materials. It extends the classical discrete element method (DEM) by the particles’ state of both thermodynamics, e.g. internal temperature distribution, and various interactions between a Šuid and a structure.