Packed-bed thermal energy storages (TES) play a major role in energy technology. During energy absorption, hot air flows through the content of the TES in top-down direction. During the heating process, the expansion of the heat-storing medium (bulk material) leads to a stress increase on the walls of heat-storage tanks. These occurring loads are to be considered by means of a discretized model. Furthermore, it is of interest how the loads modify during several loading and unloading processes (thermal ratcheting phenomenon). In this paper, it will be investigated how this behaviour can be modelled using the DEM approach.

In this work, a contact model for the simulation of crystalline solid-bridges in discrete element method (DEM) programmes is presented and compared with previous so-called bond models. The aim of the contact model is a generally valid calibration covering all states of a hygroscopic bulk material in a silo. The developed simulation model is verified by qualitative sensitivity analysis. Furthermore, a procedure for easy calibration of the required model parameters is proposed.