Conjugate heat transfer model for feedback control and state estimation in a volumetric solar receiver

• Published in: Solar energy Vol. 198; pp. 343 - 354
• Main Authors: Herrmann, Benjamín, Behzad, Masoud, Cardemil, José M., Calderón-Muñoz, Williams R., Fernández, Rubén M.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.03.2020; Pergamon Press Inc
• Subjects: Absorbers; Actuation; Air temperature; Computer applications; Computer simulation; Conjugate heat transfer; Conjugates; Control systems; Controllers; Data collection; Disturbances; Feedback; Feedback control; Heat; Heat transfer; Linear quadratic Gaussian control; Noise; Outflow; Power plants; Radiation; Reduced-order model; Solar collectors; Solar energy; Solar power; State estimation; Temperature gradients; Thermal analysis; Thermal fatigue; Thermal shock; Three dimensional models; Volumetric solar receiver; Working fluids; Conjugate heat transfer; Feedback control; State estimation; Volumetric solar receiver; Reduced-order model
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2020.01.062

•A data assimilation framework for a volumetric solar receiver is presented.•A model of the heat transfer in the absorber is shown to capture the dynamics.•Simultaneous feedback control and state estimation is performed in simulations.•Outflow temperature is stabilized during fast transients with sensor noise.•Temperature in ceramic components is estimated using sensors in the stream of air. Open volumetric solar receivers (VSRs) are a promising technology for concentrated solar power plants due to their capability to provide heat using ambient air as the working fluid operating at temperatures over 700°C. Nevertheless, VSRs are challenged by the unsteadiness and high intensity of the radiation flux, which may cause unreliable or unsafe outflow temperatures, and may compromise the lifetime of the porous ceramic absorbers due to extreme thermal loads, thermal shock or thermal fatigue. We propose a data assimilation framework to address these matters using blower actuation, measurements from sensors located in the outflow stream of air, and a model for the conjugate heat transfer in an open VSR. We formulate said model and compare it against full three-dimensional CFD simulations to show that it captures the relevant dynamics while reducing the computational cost enough to allow for online calculations. A linear quadratic Gaussian (LQG) controller is used with the model to perform simultaneous state estimation and feedback control in three simulated scenarios. Our framework proves capable of stabilizing outflow air temperatures during the passing of a cloud, estimating the radiation flux hitting the absorber during daily operation, monitoring temperature cycling in the solid matrix, and avoiding extreme temperature gradients during start-up procedures. Artificial noise and disturbances are added to the system for all scenarios and the LQG controller proves to be robust, rejecting disturbances and attenuating noise, as well as compensating for model uncertainty.