Technology Advancements for Next Generation Falling Particle Receivers

The falling particle receiver is a technology that can increase the operating temperature of concentrating solar power (CSP) systems, improving efficiency and lowering the costs of energy storage. Unlike conventional receivers that employ fluid flowing through tubular receivers, falling particle receivers use solid particles that are heated directly as they fall through a beam of concentrated sunlight for direct heat absorption and storage. Because the solar energy is directly absorbed by the particles, the flux limitations associated with tubular central receivers are mitigated. Once heated, the particles may be stored in an insulated tank and/or used to heat a secondary working fluid (e.g., steam, CO2, air) for the power cycle. Thermal energy storage costs can be significantly reduced by directly storing heat at higher temperatures in a relatively inexpensive, stable medium. This paper presents an overview of recent advancements being pursued in key areas of falling particle receiver technology, including(1) advances in receiver design with consideration of particle recirculation, air recirculation, and interconnected porous structures; (2) advances in particle materials to increase the solar absorptance and durability; and (3) advances in the balance of plant for falling particle receiver systems including thermal storage, heat exchange, and particle conveyance.