Assessment of Oxide Based Ceramic Matrix Composites as Hot Particle Transport System Components for Solar Thermal Applications

Kurzfassung

The use of solid particle technology in thermal energy storage (TES) integrated concentrated solar power (CSP) systems offers higher storage densities and lower storage costs, where solid particles are used as heat transfer and storage medium. In this application, the transport systems between the components such as solar receiver and heat storage, where ceramic particles have to be transferred with low heat losses requires appropriate material selection. High mechanical stability at elevated temperatures (|>1000 C) structural and mechanical stability after long time exposure to the heat, abrasion resistance against particle collisions, thermal shock resistance, chemical stability against particles are some of the most important properties need to be fulfilled. In this study, we manufactured aluminum oxide (Al2O3) matrix/ (Al2O3) fiber and mullite matrix/mullite fiber composites and evaluated their application related properties in a comparative manner. Mechanical properties (E-Modul and flexural strengths) in initial state and after thermal storage, abrasion resistance, thermal shock resistance were analyzed by three point bending tests, solar furnace test and particle impact test in resonance acoustic mixer; respectively. The microstructural investigation was performed by scanning electron microscopy (SEM) to reveal the effects of thermal storage. Moreover, several solid particles were stored at elevated temperatures at composite surface with subsequent SEM/EDS analysis to reveal the chemical interaction. Considering all properties, mullite based composite is determined as the most promising material for the long term use and maintenance purposes.