The intermittency of renewable energy sources necessitates storage technologies that can help to provide consistent output on-demand. A promising area of research is thermochemical energy storage (TCES), which utilizes high-temperature chemical reactions to absorb and release heat. Due to these high operating temperatures, TCES technologies are well suited for industrial processes and other applications that require high grade heat. Metal oxides have been explored as excellent candidates for high temperature redox reactions, with various authors proposing stationary and moving energy storage systems. While promising, these technologies rely on storing chemically charged TCES materials at high temperatures, complicating handling and posing serious challenges to long-duration storage.A pioneering approach known as SoFuel (solid state solar thermochemical fuel) proposed using counterflowing solid and gas streams in a particle-based moving-bed reactor to achieve heat recuperation and allow flows to enter and exit the reactor at ambient temperatures. Previous work has successfully demonstrated operation of a reduction (charging) reactor based on this concept; this dissertation describes the development of a companion oxidation (discharging) reactor. The countercurrent, tubular, moving bed oxidation setup permits solids to enter and exit at ambient temperatures, but the system also features a separate extraction port in the middle of the reactor for producing high-temperature process gas. A bench-scale experimental apparatus was fabricated for use with 5 mm particles comprised of a 1:1 molar ratio of MgO to MnO, a redox material that exhibits high oxidation temperatures (around 1000°C) and excellent cyclic stability.The experimental oxidation system successfully demonstrated self-sustaining thermochemical oxidation at temperatures in excess of 1000°C, producing sufficient energy via exothermic chemical reaction to sustain heat extraction and offset system losses. Many trials achieved largely steady operation, demonstrating operational stability during hours-long experiments. With the aid of user-manipulated inputs, the reactor produced extraction temperatures in excess of 950°C and demonstrated efficiencies as high as 41.3%. Heat losses were observed to have a strong effect on the performance of the bench-scale reactor, leading to relatively low rates of energy extraction on the order of 200-500 W. Furthermore, an extensive experimental campaign revealed thermal runaway in the upper reaches of the particle bed as a risk to safe, stable reactor operation. A rudimentary on/off recuperative gas flow control scheme was successfully implemented to mitigate runaway, although the method was unable to optimize other aspects of reactor behavior.To better understand reactor dynamics and evaluate potential control schemes, a three phase,one-dimensional finite-volume computational model was developed. The model successfully emulated behavior from the on-reactor experiments and further illustrated the impacts of the three system inputs - solid flow rate, gas extraction flow rate, and gas recuperation flow rate - on overall behavior. A five-zone adaptive model predictive controller (MPC) was developed using a linearized control-volume model as its basis. The controller sought to regulate the size, temperature, and position of the chemically reacting region of the particle bed through several novel approaches.These approaches were tuned and refined iteratively using the 1D computational model, after which they were successfully deployed on the experimental setup. Multiple control strategies allowed for successful temperature regulation, reaction zone positioning, and high-temperature gas extraction from the bench-scale reactor. Future work concerns scaling up the oxidation system for larger rates of energy extraction, further analysis of optimal reactor startup procedures, and alternative controller formulation.
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