Model predictive control of a solar-thermal reactor

Abstract

DateThe final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline.iii can preserve product quality and maintain stable product compositions, resulting in a more efficient and cost-effective operation, which can ultimately lead to scale-up and commercialization of solar thermochemical technologies. ABSTRACTIn this work, we propose a model predictive control (MPC) system for a solar-thermal reactor for the steam-gasification of biomass. The proposed controller aims at rejecting the disturbances in solar irradiation caused by the presence of clouds. A first-principles dynamic model of the process was developed. The model was used to study the dynamic responses of the process variables and to identify a linear time-invariant model used in the MPC algorithm.To provide an estimation of the disturbances for the control algorithm, a one-minute-ahead direct normal irradiance (DNI) predictor was developed. The proposed predictor utilizes information obtained through the analysis of sky images, in combination with current atmospheric measurements, to produce the DNI forecast.In the end, a robust controller was designed capable of rejecting disturbances within the operating region. Extensive simulation experiments showed that the controller outperforms a iv finely-tuned multi-loop feedback control strategy. The results obtained suggest that our controller is suitable for practical implementation.v

Numerical and experimental investigation of heat transfer in a solar receiver with a variable aperture

“…The conduction term then simplifies as shown in Eq. (12). In a similar manner, the convection term simplifies as shown in Eq.…”

“…However, since these reactors have fixed apertures, they are not able to compensate for large fluctuations in the irradiance without sacrificing other aspects of the process. The most commonly used approach to maintaining semi-constant temperatures within the solar reactor is adjusting the feedstock's flow rate to compensate for any irradiance fluctuations [11,12]. However, this approach disturbs the flow dynamics and is usually not feasible in processes where the flow pattern has to be preserved.…”

An experimental study on temperature control of a solar receiver under transient solar load

“…Fluctuations in solar radiation lead to a time-varying process heat input to the receiver which disturb the temperature stability and decrease the efficiency of the process. Closed loop control can cope with these instabilities and keep the temperature constant and increase the efficiency of the system [6,7].…”

“…In a similar study, Sadde et al used a model predictive controller for temperature regulation of a carbon steam gasification reactor. Their simulation results indicated that the controller can efficiently reject the disturbances in solar irradiation via the manipulation of the flow rates into the reactor [7]. Solar power entry manipulation is another approach which had been used for temperature control in solar reactors.…”

A Dynamic Heat Transfer Model to Investigate the Effect of Aperture Size on the Temperature of a Solar Receiver

“…On the other hand, Saade et al employed unsteady mass and energy balances to develop a simplified dynamic model for a solar thermal transport tube reactor [9]. As a follow up study, they developed a Model Predictive Control (MPC) strategy to regulate the solar reactor housing carbon steam gasification process [10]. Recently, Li et al presented a transient 3D model for hydrogen and carbon monoxide production in a solar reactor by coupling Monte Carlo ray tracing and Lattice Boltzmann (LB) model [11].…”