## 1 Introduction  
Worldwide CO\({}_{2}\) emissions and the associated global warming are forcing the exit of fossil-fueled processes in industrial applications, in electricity and heat production as well as in the transport sector. In particular for the ground-based transport sector, significant CO\({}_{2}\) reduction can be expected as a result of increasing number of battery electric vehicles(BEV) together with renewable energies. Further efficiency improvements for those vehicles are needed to increase acceptance in terms of effective range. In addition to technological advances in battery development, new thermal management concepts play a central role, allowing electrical energy consumption for cabin climatization to be minimized. For example, current battery-powered PTC heaters lead to range losses of up to 50% during cold seasons [1; 2], whereas efficient heat pump systems with lower electrical energy demands allow effective range improvements. Another promising technology are thermal energy storage systems. They improve as a separate component or in combination with heat pumps the overall efficiency, thus range extensions. So far, commercial as well as R&D based activities focus on large scale applications, e.g., for the flexibilization of industrial [3; 4] or power plant processes [5; 6] as well as for novel electrical heated storage systems [7; 8]. The basic idea is to store heat efficiently in the process at times of low thermal energy demand (charging period) and to provide it to the process at times of increased thermal energy demand (discharging period). With this time-decoupled operation systemic efficiency and flexibility improvements are achieved. Thermal energy storage systems are classified as sensible [9; 10], latent [11] or thermochemical systems [12], whereby their application potential depends on the maximum operating temperature, the heat transfer medium, the charging/discharging durations or system requirements. Additionally, technological developments have been taking place for some years towards upscaled high-temperature heating systems. These concepts allow in combination with thermal energy storage systems additional increases in systemic flexibility and cost efficiency. Particularly for sensible thermal energy storage systems based on solids, inductive or conductive heating systems are being developed, which aim to elevate the temperature level with simultaneous high load gradients [13]. Compared to large-scale applications, studies on the application potential of thermal energy storage systems in the transport sector have so far played a minor role. Except for preheating of catalysts [14] and combustion engines [15] as well as for cooling applications [16], investigations were mainly focused on thermochemical storage systems (gas-solid reactions), offering an alternative heat and cold supply [17; 18] for fuel cell vehicles. In recent years, an increasing number of publications have appeared for the heat supply of battery electric vehicles with thermal energy storage concepts based on phase change materials (PCM) [19; 20; 21; 22] and on solid media [23; 24]. Here, during the charging period the required heat is generated electrically, transferred to the storage material and used during discharging for heating the interior by a mass flow-controlled bypass. For a successful use of such thermal energy storage concepts in battery electric vehicles, systemic benefits compared to conventional battery powered PTC systems must be given. This challenge is strongly linked with high systemic storage and power densities and must be justified on today's commercial Li-Ion batteries operating in a range from 110 Wh/kg to 160 Wh/kg [25]. A favorite technology for this purpose is based on electrically heated solid medium thermal energy storage system (regenerator), which achieves all target values in terms of high charging/discharging performance, constant discharge temperature and high systemic storage densities.