Session: 03-02: High Temperature Thermal Storage

Paper Number: 142460

142460 - The Significance of Boundary Layer Thickness in Thermochemical Reactors for Extended Duration Energy Storage 

Abstract: 

The study signifies a momentous leap forward in the realm of thermochemical energy storage, particularly concentrating on metal oxide particle-based inert-swept reduction reactors. These reactors hold significant promise for extended-duration energy storage, a pivotal element in sustainable energy ecosystems. The crux of this advancement lies in the unveiling of a specialized analytical mass transfer model that provides invaluable insights into optimizing reactor functionality. This research analyzes the factors responsible for extracting the utmost quantity of oxygen during thermochemical reduction, while concurrently curtailing the sweep gas flow rate, a critical reactor cost parameter. An overarching challenge tackled by this study is the optimization of the boundary layer thickness within the reactor, a pivotal parameter in sizing reactors. The boundary layer thickness determines the maximum particle density permissible within the reactor without causing oxygen accumulation near the particles. By maximizing particle density through this optimization process, the objective is to maximize the power density while simultaneously minimizing reactor dimensions and costs. This optimization considers various reactor constraints such as sweep gas pressure drops, sweep gas utilization efficiency and oxygen back-diffusion. As per the analytical model, increasing the gas velocity within the reactor has twofold effects. Firstly, it amplifies the mass transfer coefficient, thereby augmenting the efficiency of oxygen transfer within the system. Secondly, it decreases the boundary layer thickness, thereby facilitating more efficient mass transfer mechanisms, findings that emphasize the role of regulating gas velocity in improving the reactor performance. Furthermore, the study highlights the pivotal role of particle diameter in influencing both particle and power density within the reactor. Larger particle diameters lead to higher particle density, thus culminating in higher power density, an observation that underscores the careful selection of particle sizes in the conception and operation of thermochemical reduction reactors. The findings presented in the study are highly promising, with projected power densities of up to 10 MW/m³ achievable with the use of CAM28. Such high power densities signify a significant advancement in the field of thermochemical reduction reactors and offer exciting prospects for future thermochemical energy storage technologies. Larger particles also allow for thinner particle beds, thereby decreasing the reactor particle density without decreasing the power density. To add confidence in the analytical model's results, the study also incorporates verification via a computational model, thereby enabling a holistic comprehension of the reactor's performance attributes. The discoveries offer a deeper understanding of thermochemical reactors, enabling the design of cost-effective thermochemical reactors without compromising performance.

Presenting Author: Rhushikesh Ghotkar Arizona State University

Presenting Author Biography: Through my research with the Lightworks® Lab at Arizona State University, I am developing technologies to employ thermochemical energy storage for weekly and seasonal grid-scale storage applications. I have prior experience developing several high-temperature thermochemical systems like solid oxide fuel cells, metal oxide reduction reactors, and gas turbines. I am intrigued by the looming energy crisis and would love to do my part in creating a more sustainable and energy-efficient civilization.

Authors:

Rhushikesh Ghotkar Arizona State University
Ryan Milcarek Arizona State University
Ivan Ermanoski Arizona State University
Ellen Stechel Arizona State University