On-sun testing of a 1 MWt particle receiver with automated particle mass-flow and temperature control

This paper describes on-sun testing of an automated system that controls the particle mass flow and outlet temperature in a high-temperature falling particle receiver. A slide gate with a linear actuator was designed and implemented in a closed-loop feedback system that varied the particle mass flow rate to maintain a desired bulk particle outlet temperature. The system was designed to operate at high temperatures (>700 °C) and relatively large mass flow rates (∼1 - 10 kg/s and higher). On-sun tests were performed at different irradiances, particle inlet temperatures, and particle mass flow rates. Results showed that the automated system could maintain desired particle outlet temperatures from ∼300 – 650 °C for most test conditions. During significant flux perturbations, oscillations (or ringing) about the desired setpoint temperature was observed, which is common for simple proportional control systems. Future studies will investigate more advanced proportional integral derivative methods to dampen the oscillations and provide tighter controls. Particle temperature rise and thermal efficiency were also measured during the on-sun tests and are reported. Finally, the particle mass flow rate as a function of slide-gate aperture and particle temperature was measured, and a new correlation was derived.