In recent years, the fight against global warming and therefore CO${}_2$ reduction have become the most important issue for humanity. As a result, volatile sources of energy—like wind and solar power—are penetrating the electrical grid and therefore an increased demand on storage capacities is required. At the TU Wien Institute for Energy Systems and Thermodynamics, a Fluidization Based Particle Thermal Energy Storage (FP-TES) working with bulk material as a sensible storage material is developed. In this paper, the concept and an experimental study of the cold test rig is presented. By means of various pressure measurements, a novel concept of particle transport based on advanced fluidization technology without any mechanical transport devices is investigated. Moreover, a mathematical correlation between the pressure gradients and the particle mass flow is found. Overall, the experimental study provides a full proof of concept and functionality of the novel energy storage system.

Renewables should become more continuously available, reliable and cost-efficient to manage the challenges caused by the energy transition. Thus, analytic and numerical investigations for the layout of a pilot plant of a concept called Fluidisation-Based Particle Thermal Energy Storage (FP-TES)—a highly flexible, short- to long-term fluidised bed regenerative heat storage utilising a pressure gradient for hot powder transport, and thus enabling minimal losses, high energy densities, compact construction and countercurrent heat exchange—are presented in this article. Such devices in decentralised set-up—being included in energy- and especially heat-intensive industries, storing latent or sensible heat or power-to-heat to minimise losses and compensate fluctuations—can help to achieve the above-stated goals. Part I of this article is focused on geometrical and fluidic design via numerical investigations utilising Computational Particle Fluid Dynamics (CPFD). In the process a controlled transient simulation method called co-simulation of FP-TES is developed forming the basis for test bench design and execution of further co-simulation. Within this process an advanced design of rotational symmetric hoppers with additional baffles in the heat exchanger (HEX) and internal pipes to stabilise the particle mass flow is developed. Moreover, a contribution bulk heat conductivity is presented to demonstrate low thermal losses and limited needs for thermal insulation by taking into account the thermal insulation of the outer layer of the hopper.