M. Obermaier’s research while affiliated with TU Wien and other places

Flexible dispatch able solar thermal electricity plants applying state of the art power cycles have the potential of playing a vital role in modern electricity systems and even participating in the ancillary market. By replacing molten salt via particles, operation temperatures can be increased and plant efficiencies of over 45 % can be reached. In this work the concept for a utility scale plant using corundum as storage/heat transfer material is thermodynamically modeled and its key performance data are cited. A novel indirect fluidized bed particle receiver concept is presented, profiting from a near black body behavior being able to heat up large particle flows by realizing temperature cycles over 500°C. Specialized fluidized bed steam-generators are applied with negligible auxiliary power demand. The performance of the key components is discussed and a rough sketch of the plant is provided.

For direct particle absorption CSP-plants heat exchanger between particles and the working fluid of the power cycle are needed. A fluidized-bed heat-exchanger design operating close to the minimum fluidization condition is proposed in this work. Its basic design and core components are explained.For illustrating the performance of this fluidized-bed heat-exchanger its application as evaporator and superheater in sub- and supercritical cycle are presented. Therefore overall design parameters of all heat exchangers and a detailed process flow diagram including all major componentsare shown.

An active fluidization thermal energy storage (TES) called “sandTES” is presented. System design, the fundamental features and challenges of fluidization stability such as mass flux uniformity, powder transport and heat transfer, as well as auxiliary power minimization are thoroughly discussed. The tools and methods for evaluating or simulating the behavior of the fluidized bed heat exchanger (HEX) and the dense particle flow within it are explained along with criteria for the selection of storage powders.