Optimizing Aperture to Beam Size Ratios in Multi-Flow Falling Particle Receivers

High-temperature solar thermal technologies, such as Concentrated Solar Power (CSP), utilize heliostats to focus sunlight on a central receiver where thermal medium is heated to a high temperature and stored. Then the thermal medium can be used in a variety of heat engine cycles to generate dispatchable electricity. While many modern CSP systems use molten salts as the medium, with peak temperature limited to 700°C, falling particle receivers offer an option for achieving higher temperatures and thus increasing thermodynamic efficiency. Conventional particle receivers are typically equipped with a slide gate and an actuator. However, this study utilizes a multi-flow particle receiver, which consists of ten individually controlled valves, each containing a slide gate and an actuator. This design allows each section to have its own mass flow rate, which our group’s previous research has proven to be more efficient. This study focuses on optimizing the aperture size for a given beam size and power input in a multi-flow particle receiver. This study focuses on optimizing the aperture size for a given beam size and power input in a multi-flow particle receiver. A parametric analysis was conducted to assess the impact of optimizing the aperture size for a given beam size on thermal efficiency, heat loss, and energy capture. Results indicate that optimizing the aperture size for a given beam size ratio enhances efficiency by balancing solar energy capture and heat losses, contributing to a cost-effective CSP system aligned with the US Department of Energy goals. We show that the optimal aperture to beam size ratio ranges between 50% and 80% throughout the day, from 7 AM to 5 PM. Each hour has a unique optimal aperture to beam size ratio, and a variable aperture mechanism could hold potential for optimizing performance; however, this study is limited to the case of an optimal fixed aperture to beam size ratio.