Characterization of particle heat carriers for solar particle receivers for pyrolysis application

The use of Particle Heat Carriers (PHCs) for high-temperature heat transfer has attracted growing attention due to their ability to store significant thermal energy, withstand extreme conditions, and ensure efficient heat exchange in applications such as industrial processes and solar reactors. A detailed understanding of PHC properties is crucial for optimizing system performance. This study provides a comprehensive characterization of five widely used PHCs—bauxite, silicon carbide, magnesium oxide, olivine, and sand—focusing on their thermal, mechanical, and chemical properties for biomass pyrolysis applications. A distinctive aspect of this work is the inclusion of biochar in the analysis, offering new insights into its potential as a sustainable heat transfer medium. Results highlight the importance of property-based selection criteria for PHCs and demonstrate the value of systematic evaluation for high-temperature applications. Among the tested materials, bauxite, olivine, and sand emerged as the most suitable candidates, achieving a balanced combination of thermal stability, mechanical strength, and chemical compatibility. Silicon carbide also showed favorable characteristics but suffered from high abrasion. Although biochar offers economic and logistical advantages, its limited mechanical robustness restricts its suitability for this purpose.