A review of directly irradiated solid particle receivers: Technologies and influencing parameters

In concentrated solar power (CSP) systems, increasing the heat transfer fluid (HTF) temperature leads to efficient operation by reducing energy loss from thermal receivers. Moreover, CSP systems with high HTF temperatures allow thermal energy storage (TES) to supply the overnight demand. One of the most commonly used ways to implement TES in commercial CSP systems is using molten salts as HTFs. However, using such HTFs limits the operating temperature to less than 800 °C to ensure their stability. To overcome such limitation, using receivers operated by solid particles as both HTF and TES medium has emerged as a promising solution, as some particles can reach temperatures exceeding 1000 °C. Solid particles are directly heated by falling through concentrated sunlight in the solid particle receiver (SPR). SPRs are categorized into directly and indirectly irradiated types. This work focuses on directly irradiated SPRs, as they represent the most common systems. This review covers different subcategories of directly irradiated SPRs that attracted the researchers to investigate. It also presents an overview of the current research trends through statistical analysis of reviewed literature. Finally, the present work also analyzed different parameters influencing SPRs performance according to the findings cited in the literature.