Session: 03-01 Thermochemical Energy Storage

Paper Number: 114575

114575 - Experimental Demonstration of the Dynamics of a Novel Thermochemical Oxidation Reactor 

Thermochemical energy storage technologies utilize high-temperature chemical reactions to capture energy and save it for later use. Metal oxide redox systems feature reduction (charging) and oxidation (discharging) steps, with most systems storing reduced materials at elevated temperatures prior to oxidation. A novel countercurrent, tubular, moving bed oxidation reactor was previously demonstrated that produces high grade heat and allows materials to enter and exit at ambient temperatures. Opposing downward particle and upward gas flows minimize axial losses and isolate high temperatures to a reaction zone near the middle of the reactor tube. Heat extraction is achieved via a separate gas flow that exits directly from the reaction zone, with a maximum demonstrated extraction temperature of 973°C. The reactor utilizes Mg-Mn-O particles and is the companion to a reduction reactor that operates under a similar counterflow design. This work investigates system dynamics and operational strategies for the novel oxidation reactor. Several experiments are carried out on the laboratory scale oxidation reactor to characterize system behavior. The system exhibits long-duration operation with average extraction temperatures over 800°C for each experiment. Reaction zone size, location, and temperature are strongly affected by solid and gas flow rates. A particularly notable phenomenon is the “runaway” reaction zone, which occurs when gas flow rates in the upper reaches of the particle bed provide sufficient heat transfer for a self-sustaining upward exothermic reaction. Several control strategies are considered for regulating reactor operation. An on/off control for recuperative gas flow based on bed temperature is implemented. The control is successful in eliminating “runaway” reaction zone behavior. Future work will incorporate standard control theories such as model predictive control.

Presenting Author: Michael Hayes Michigan State University

Presenting Author Biography: Michael Hayes is a PhD candidate at Michigan State University. His research focuses on thermochemical energy storage and the experimental implementation of new reactor designs. He is a member of the multi-university SoFuel project, a U.S. Department of Energy-funded effort to produce a metal oxide solid-state solar fuel that can be stored under ambient conditions.