<p>Falling particle receiver (FPR) systems are a rapidly developing technology for concentrating solar power applications. Solid particles are used as both the heat transfer fluid and system thermal energy storage media. Through the direct irradiation of the solid particles, flux and temperature limitations of tube-bundle receives can be overcome leading to higher operating temperatures and energy conversion efficiencies. Candidate particles for FPR systems must be resistant to changes in optical properties during long term exposure to high temperatures and thermal cycling using highly concentrated solar irradiance. Five candidate particles, CARBO HSP 40/70, CARBO CP 40/100, including three novel particles, CARBO KRYPTOSPHERE, CARBO Solar HD 350, and WanLi Diamond Black, were tested using simulated solar flux cycling and tube furnace thermal aging. Each particle candidate was exposed for 10000 cycles (30-year lifetime) using a shutter to attenuate the solar simulator flux. Feedback from a pyrometer temperature measurement of the irradiated particle surface was used to control the maximum temperatures of 775°C and 1000°C. Particle solar-weighted absorptivity and emissivity were measured at 2000 cycle intervals. Particle thermal degradation was also studied by heating particles to 800°C, 900°C, and 1000°C for 300 hours in a tube furnace purged with bottled air. Here particle absorptivity and emissivity were measured at 100-hour intervals. Measurements taken after irradiance cycling and thermal aging were compared to measurements taken from as-received particles. Wan Li Diamond Black particles had the highest initial value for solar weighted absorptance, 96%, but degraded up to 4% in irradiance cycling and 6% in thermal aging. CARBO HSP 40/70 particles currently in use in the prototype FPR at the National Solar Thermal Test Facility had an initial value of 95% solar absorptance with up to a 1% drop after irradiance cycling and 4% drop after thermal aging.</p>

Assesment of Particle Candidates for Falling Particle Receiver Applications Through Irradiance and Thermal Cycling

Paper Proceedings: https://asmedigitalcollection.asme.org/ES/ES2021/volume/84881

ASME 2021 Energy Sustainability (ES2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.